Scholars@Duke
Daniel D. Richter

Daniel D. Richter

Theodore S. Coile Distinguished Professor
Earth and Climate Sciences
drichter@duke.edu
Box 90328, Durham, NC 27708-0328
A205 Lab; Lev Sci Res Ctr, Science Dr., Durham, NC 27708

Selected Publications

Strontium isotopes and Rb/Sr tracers in surface soils for locating subsurface lithium pegmatites

Journal Article Applied Geochemistry · December 1, 2025 Lithium-cesium-tantalum (LCT) pegmatites are a major source of global Li production. They typically occur as dike swarms intruded into metamorphic country rocks. The subsurface locations of these dikes can be difficult to identify from the surface. One com ... Full text Cite

Contrasting Depth Dependencies of Plant Root Presence and Mass Across Biomes Underscore Prolific Root-Regolith Interactions

Journal Article Agu Advances · December 1, 2025 Root distributions are typically based on root mass per soil volume. This plant-focused approach masks the biogeochemical influence of fine roots, which weigh little. We assert that centimeter-scale root presence-absence data from soil profiles provide a m ... Full text Cite

Using Seismic Refraction Data to Estimate a Relationship Between Landscape Curvature and Deep Critical Zone Structure in the South Carolina Piedmont, USA

Journal Article Journal of Geophysical Research Earth Surface · November 1, 2025 P-wave velocity profiles from seismic refraction reveal deep critical zone (CZ) architecture along profiles hundreds of meters long. However, extrapolating local velocity measurements to infer CZ architecture at regional scales (1–20 km2) remain ... Full text Cite

LIBS as a tool for Li-pegmatite exploration and prospect evaluation: Soil mica and soil analysis from the Carolina Tin-Spodumene Belt

Journal Article Applied Geochemistry · October 1, 2025 Lithium is an essential element along the pathway to a high-technology future. Being able to efficiently explore for Li deposits and fully assess prospects is necessary to reduce exploration costs, shorten time between discovery and production, and minimiz ... Full text Cite

On the role of inherited rock fabric in critical zone porosity development: Insights from seismic anisotropy measurements using surface waves

Journal Article Earth Surface Processes and Landforms · July 1, 2025 Within Earth's critical zone, weathering processes influence landscape evolution and hillslope hydrology by creating porosity in bedrock, transforming it into saprolite and eventually soil. In situ weathering processes drive much of this transformation whi ... Full text Cite

Persistent biogeochemical signals of land use-driven, deep root losses illuminated by C and O isotopes of soil CO2 and O2

Journal Article Biogeochemistry · December 1, 2024 Replacing long-lived, rarely disturbed vegetation with short-lived, frequently disturbed vegetation is a widespread phenomenon in the Anthropocene that can influence ecosystem functioning and soil development by reducing the abundance of deep roots. We exp ... Full text Cite

Soil phosphorus continues to re-equilibrate over 60 years of forest development in the Calhoun Critical Zone Observatory in the southeastern US Piedmont

Journal Article Soil Science Society of America Journal · July 1, 2024 Land use changes and reforestation impact soil phosphorus (P) distribution over extended periods. This study examines P distribution in forest development from 1957 to 2017 at the Calhoun Critical Zone Observatory in South Carolina. Tracking changes in 0–6 ... Full text Cite

The primacy of temporal dynamics in driving spatial self-organization of soil iron redox patterns.

Journal Article Proceedings of the National Academy of Sciences of the United States of America · December 2023 This study investigates mechanisms that generate regularly spaced iron-rich bands in upland soils. These striking features appear in soils worldwide, but beyond a generalized association with changing redox, their genesis is yet to be explained. Upland soi ... Full text Cite

Legacies of Pre-1960s Municipal Waste Incineration in the Pb of City Soils.

Journal Article Environmental science & technology letters · October 2023 A 1937 street map of Durham, North Carolina, located four city-run waste incinerators that we recognized to be sites of contemporary city parks. We obtained city permission to sample three park's soils, developed a sampling design for geospatial mapping of ... Full text Cite

Phosphorus Fluxes in a Restored Carolina Bay Wetland Following Eight Years of Restoration

Journal Article Wetlands · August 1, 2023 Restoring wetlands on agricultural land can release soil phosphorus (P) to surface waters. Phosphorus is a limiting nutrient in many freshwater systems, thus restricting its release will improve surface water quality by preventing algal blooms. A P balance ... Full text Cite

Integrating decadal and century-scale root development with longer-term soil development to understand terrestrial nutrient cycling

Journal Article Geoderma · July 1, 2023 Nearly 50 y ago, Walker and Syers hypothesized that sources of most terrestrial nutrients shift in dominance from mineral- to organic matter-derived over millennia as soils weather. We investigated how overlaying this soil development framework with vegeta ... Full text Cite

Past critique but much praise for restoration ecology: four decades on

Journal Article Restoration Ecology · May 1, 2023 During the last four decades, restoration ecology has prevailed and flourished in the academy and the public square. During this time, both ecology and restoration ecology have moved away from presenting ecosystem development as a trajectory that can retur ... Full text Cite

Soil

Chapter · January 1, 2023 The science of pedology has historically studied how soils form in response to natural factors and processes. Today, with soils being so extensively altered by human action, pedology is adapting to the fundamental changes that are ongoing in our objects of ... Full text Cite

Mineralogical and Elemental Trends in Regolith on Historically Managed Sites in the southeastern United States Piedmont

Journal Article Clays and Clay Minerals · August 1, 2022 The deep regolith of the southeastern United States has undergone rapid erosion in the last two centuries due to intensive agricultural practices, which has altered the landscape and its inherent fertility. Parent material, landscape position, and land use ... Full text Cite

Quantitative analysis of hillshed geomorphology and critical zone function: Raising the hillshed to watershed status

Journal Article Bulletin of the Geological Society of America · July 1, 2022 Landscapes are frequently delineated by nested watersheds and river networks ranked via stream orders. Landscapes have only recently been delineated by their interfluves and ridge networks, and ordered based on their ridge connectivity. There are, however, ... Full text Cite

Legacy of anthropogenic lead in urban soils: Co-occurrence with metal(loids) and fallout radionuclides, isotopic fingerprinting, and in vitro bioaccessibility.

Journal Article The Science of the total environment · February 2022 Anthropogenic lead (Pb) in soils poses risks to human health, particularly to the neuropsychological development of exposed children. Delineating the sources and potential bioavailability of soil Pb, as well as its relationship with other contaminants is c ... Full text Open Access Cite

Embracing the dynamic nature of soil structure: A paradigm illuminating the role of life in critical zones of the Anthropocene

Journal Article Earth Science Reviews · February 1, 2022 Soils form the skin of the Earth's surface, regulating water and biogeochemical cycles and generating production of food, timber, and textiles around the world. Changes in soil and its ability to perform a range of processes have important implications for ... Full text Cite

Searching for solutions to our soil woesA World Without Soil: The Past, Present, and Precarious Future of the Earth Beneath Our FeetJo Handelsman Yale University Press, 2021. 272 pp.

Journal Article Science (New York, N.Y.) · December 2021 Could a controversial carbon storage plan help restore degraded lands? ... Full text Cite

Mapping antebellum rice fields as a basis for understanding human and ecological consequences of the era of slavery

Journal Article Land · August 1, 2021 Model systems enlightened by history that provide understanding and inform contemporary and future landscapes are needed. Through transdisciplinary collaboration, historic rice fields of the southeastern United States can be such models, providing insight ... Full text Cite

Gully-erosion estimation and terrain reconstruction using analyses of microtopographic roughness and LiDAR

Journal Article Catena · July 1, 2021 Gully mapping techniques successfully identify gullies over a large range of breadths and depths in complex landscapes but practices for estimating gully volumes need further development. Gully gap-interpolation for estimation of gully volume does not ofte ... Full text Open Access Cite

Urban-Soil Pedogenesis Drives Contrasting Legacies of Lead from Paint and Gasoline in City Soil.

Journal Article Environmental science & technology · June 2021 This study analyzed the impact of urban-soil pedogenesis on soil lead (Pb) contamination from paint and gasoline in the historic core of Durham, North Carolina. Total soil Pb in 1000 samples from streetsides, residential properties, and residual upland and ... Full text Cite

The Anthropocene: Comparing Its Meaning in Geology (Chronostratigraphy) with Conceptual Approaches Arising in Other Disciplines

Journal Article Earth's Future · March 2021 AbstractThe term Anthropocene initially emerged from the Earth System science community in the early 2000s, denoting a concept that the Holocene Epoch has terminated as ... Full text Cite

Spatial-temporal association of soil Pb and children's blood Pb in the Detroit Tri-County Area of Michigan (USA).

Journal Article Environmental research · December 2020 Lead is a well-known toxicant associated with numerous chronic diseases. Curtailing industrial emissions, leaded paint, lead in food, and banning highway use of leaded gasoline effectively decreased children's exposure. In New Orleans, irrespective of Hurr ... Full text Open Access Cite

Agricultural acceleration of soil carbonate weathering.

Journal Article Global change biology · October 2020 Soil carbonates (i.e., soil inorganic carbon or SIC) represent more than a quarter of the terrestrial carbon pool and are often considered to be relatively stable, with fluxes significant only on geologic timescales. However, given the importance of climat ... Full text Open Access Cite

Impact of gully incision on hillslope hydrology

Journal Article Hydrological Processes · September 15, 2020 The Southern U.S. Piedmont ranging from Virginia to Georgia underwent severe gully erosion over a century of farming mainly for cotton (1800s–1930s). Although tree succession blanketed much of this region by the middle 20th century, gully erosion still occ ... Full text Open Access Cite

Limited carbon contents of centuries old soils forming in legacy sediment

Journal Article Geomorphology · April 1, 2020 Accelerated erosion from European agriculture overwhelmed transport capacities of relatively low-gradient Piedmont watersheds and triggered widespread and massive sediment deposition on floodplains, referred to as legacy sediments. While erosion-driven soi ... Full text Open Access Cite

Game Changer in Soil Science. The Anthropocene in soil science and pedology.

Journal Article Journal of Plant Nutrition and Soil Science · February 1, 2020 The venerable science of pedology, initiated in the 19th century as the study of the natural factors of soil formation, is adapting to the demands of the Anthropocene, the geologic time during which planet Earth and its soils are transitioning f ... Full text Open Access Cite

Persistent anthropogenic legacies structure depth dependence of regenerating rooting systems and their functions

Journal Article Biogeochemistry · February 1, 2020 Biotically-mediated weathering helps to shape Earth’s surface. For example, plants expend carbon (C) to mobilize nutrients in forms whose relative abundances vary with depth. It thus is likely that trees’ nutrient acquisition strategies—their investment in ... Full text Open Access Cite

Quantification of Mixed-Layer Clays in Multiple Saturation States Using NEWMOD2: Implications for the Potassium Uplift Hypothesis in the SE United States

Journal Article Clays and Clay Minerals · February 1, 2020 Quantification of mineral assemblages in near-surface Earth materials is a challenge because of the often abundant and highly variable crystalline and chemical nature of discrete clay minerals. Further adding to this challenge is the occurrence of mixed-la ... Full text Open Access Cite

Soil production and the soil geomorphology legacy of Grove Karl Gilbert

Journal Article Soil Science Society of America Journal · January 1, 2020 Geomorphologists are quantifying the rates of an important component of bedrock's weathering in research that needs wide discussion among soil scientists. By using cosmogenic nuclides, geomorphologists estimate landscapes’ physical lowering, which, in a st ... Full text Open Access Cite

Ansichten der Calzone: Views from the Calhoun Critical Zone Observatory

Chapter · 2020 The German title of our piece fo#ows Ale"ander von Humboldt, to honor his 250th birthday in 2019. Humboldt’s Ansichten der Natur1 was !rst published in 1804 after his !ve-year e"pedition to the Americas. Ansichten was a sma# book that fused geology and bio ... Open Access Cite

Floodplain and Terrace Legacy Sediment as a Widespread Record of Anthropogenic Geomorphic Change

Journal Article Annals of the American Association of Geographers · January 1, 2020 Anthropogenic erosion and sedimentation are critical components of global change that involve life-sustaining natural resources of soil and water. Many geomorphic systems have responded to intense land use disturbance with episodic erosion and sedimentatio ... Full text Cite

State of Forest and Rangeland Soils Research in the United States

Chapter · January 1, 2020 Flying across the eastern United States at an altitude of 10, 000 m, we see a landscape below that is a mosaic of forests, rivers, farm fields, towns, and cities. Almost all of the lands covered by forests today have undergone intensive harvest, and even r ... Full text Cite

Biogeochemical Cycling in Forest and Rangeland Soils of the United States

Chapter · January 1, 2020 In the Sand County Almanac (Leopold 1949), Aldo Leopold writes of the odyssey of element X and thus of the circulation of all nutrient elements as they cycle through the Earth’s forests, rangelands, lakes, and oceans. In mid-century, G.E. Hutchinson, while ... Full text Cite

The effect of accelerated soil erosion on hillslope morphology

Journal Article Earth Surface Processes and Landforms · December 1, 2019 Intensive agricultural land use can have detrimental effects on landscape properties, greatly accelerating soil erosion, with consequent fertility loss and reduced agricultural potential. To quantify the effects of such erosional processes on hillslope mor ... Full text Open Access Cite

Ecological and Genomic Attributes of Novel Bacterial Taxa That Thrive in Subsurface Soil Horizons.

Journal Article mBio · October 2019 While most bacterial and archaeal taxa living in surface soils remain undescribed, this problem is exacerbated in deeper soils, owing to the unique oligotrophic conditions found in the subsurface. Additionally, previous studies of soil microbiomes have foc ... Full text Open Access Cite

A formal Anthropocene is compatible with but distinct from its diachronous anthropogenic counterparts: a response to W.F. Ruddiman’s ‘three flaws in defining a formal Anthropocene’

Journal Article Progress in Physical Geography · June 1, 2019 We analyse the ‘three flaws’ to potentially defining a formal Anthropocene geological time unit as advanced by Ruddiman (2018). (1) We recognize a long record of pre-industrial human impacts, but note that these increased in relative magnitude slowly and w ... Full text Open Access Cite

Estimates and determinants of stocks of deep soil carbon in Gabon, Central Africa

Journal Article Geoderma · May 1, 2019 Despite the importance of tropical forest carbon to the global carbon cycle, research on carbon stocks is incomplete in major areas of the tropical world. Nowhere in the tropics is this more the case than in Africa, and especially Central Africa, where car ... Full text Open Access Cite

Micro-topographic roughness analysis (MTRA) highlights minimally eroded terrain in a landscape severely impacted by historic agriculture

Journal Article Remote Sensing of Environment · March 1, 2019 The 190 km2 Calhoun Critical Zone Observatory in the Piedmont region of South Carolina, USA lies in an ancient, highly weathered landscape transformed by historic agricultural erosion. Following the conversion of largely hardwood forests to cult ... Full text Open Access Cite

Links between physical and chemical weathering inferred from a 65-m-deep borehole through Earth's critical zone.

Journal Article Scientific reports · March 2019 As bedrock weathers to regolith - defined here as weathered rock, saprolite, and soil - porosity grows, guides fluid flow, and liberates nutrients from minerals. Though vital to terrestrial life, the processes that transform bedrock into soil are poorly un ... Full text Open Access Cite

Distinct contributions of eroding and depositional profiles to land-atmosphere CO2 exchange in two contrasting forests

Journal Article Frontiers in Earth Science · February 26, 2019 Lateral movements of soil organic C (SOC) influence Earth's C budgets by transporting organic C across landscapes and by modifying soil-profile fluxes of CO2. We extended a previously presented model (Soil Organic C Erosion Replacement and Oxida ... Full text Open Access Cite

Redoximorphic Bt horizons of the Calhoun CZO soils exhibit depth-dependent iron-oxide crystallinity

Journal Article Journal of Soils and Sediments · February 12, 2019 Purpose: Iron (Fe) oxyhydroxides and their degree of ordering or crystallinity strongly impact the role that Fe plays in ecosystem function. Lower crystallinity phases are generally found to be more reactive than higher crystallinity phases as sorbents for ... Full text Open Access Cite

Development and deployment of a field-portable soil O2 and CO2 gas analyzer and sampler.

Journal Article PloS one · January 2019 Here we present novel method development and instruction in the construction and use of Field Portable Gas Analyzers study of belowground aerobic respiration dynamics of deep soil systems. Our Field-Portable Gas Analysis (FPGA) platform has been developed ... Full text Open Access Cite

How to estimate statistically detectable trends in a time series: A study of soil carbon and nutrient concentrations at the calhoun LTSE

Conference Soil Science Society of America Journal · January 1, 2019 Quantifying rates of change in soil carbon and nutrients is essential to understanding the global carbon cycle as well as to guiding local management decisions. However, change in soils can be nonlinear, difficult to detect, and dependent on the depth of s ... Full text Cite

Mercury Sourcing and Sequestration in Weathering Profiles at Six Critical Zone Observatories

Journal Article Global Biogeochemical Cycles · October 1, 2018 Mercury sequestration in regolith (soils + weathered bedrock) is an important ecosystem service of the critical zone. This has largely remained unexplored, due to the difficulty of sample collection and the assumption that Hg is predominantly sequestered w ... Full text Open Access Cite

Carbon and oxygen isotope composition in soil carbon dioxide and free oxygen within deep ultisols at the Calhoun CZO, South Carolina, USA

Conference Radiocarbon · October 1, 2018 In order to evaluate effects of three land uses on isotopic compositions of CO2 and O2 of soil air to 5 m soil depth, a field study was conducted in the Calhoun Critical Zone Observatory, located in the subtropical climate of the Southern Piedmo ... Full text Open Access Cite

The Formation of Clay-Enriched Horizons by Lessivage

Journal Article Geophysical Research Letters · August 16, 2018 Soils with argillic horizons comprise more than 25% of the Earth's surface. Although their origin is still debated, lessivage is often invoked to explain them, but the long timescales involved hinder its direct experimental verification. We present a parsi ... Full text Open Access Cite

Ideas and perspectives: Strengthening the biogeosciences in environmental research networks

Journal Article Biogeosciences · August 15, 2018 Long-term environmental research networks are one approach to advancing local, regional, and global environmental science and education. A remarkable number and wide variety of environmental research networks operate around the world today. These are diver ... Full text Open Access Cite

Modifications of 2:1 clay minerals in a kaolinite-dominated Ultisol under changing land-use regimes

Journal Article Clays and Clay Minerals · February 1, 2018 Chemical denudation and chemical weathering rates vary under climatic, bedrock, biotic, and topographic conditions. Constraints for landscape evolution models must consider changes in these factors on human and geologic time scales. Changes in nutrient dyn ... Full text Open Access Cite

Loss of deep roots limits biogenic agents of soil development that are only partially restored by decades of forest regeneration

Journal Article Elementa · January 1, 2018 Roots and associated microbes generate acid-forming CO2 and organic acids and accelerate mineral weathering deep within Earth's critical zone (CZ). At the Calhoun CZ Observatory in the USA's Southern Piedmont, we tested the hypothesis that defor ... Full text Open Access Cite

Designing a network of critical zone observatories to explore the living skin of the terrestrial Earth

Journal Article Earth Surface Dynamics · December 18, 2017 The critical zone (CZ), the dynamic living skin of the Earth, extends from the top of the vegetative canopy through the soil and down to fresh bedrock and the bottom of the groundwater. All humans live in and depend on the CZ. This zone has three co-evolvi ... Full text Open Access Cite

Boom and bust carbon-nitrogen dynamics during reforestation

Journal Article Ecological Modelling · September 24, 2017 Legacies of historical land use strongly shape contemporary ecosystem dynamics. In old-field secondary forests, tree growth embodies a legacy of soil changes affected by previous cultivation. Three patterns of biomass accumulation during reforestation have ... Full text Open Access Cite

Hydro‐geomorphic perturbations on the soil‐atmosphere CO2exchange: How (un)certain are our balances?

Journal Article Water Resources Research · February 2017 AbstractAttempts to estimate the influence of erosion on the carbon (C) cycle are limited by difficulties in accounting for the fate of mobilized organic material and for the uncertainty associated with land management prac ... Full text Open Access Cite

Making the case for a formal Anthropocene Epoch: An analysis of ongoing critiques

Journal Article Newsletters on Stratigraphy · January 1, 2017 A range of published arguments against formalizing the Anthropocene as a geological time unit have variously suggested that it is a misleading term of non-stratigraphic origin and usage, is based on insignificant temporal and material stratigraphic content ... Full text Open Access Cite

The influence of Dan H. Yaalon: His impact on people

Journal Article Catena · November 1, 2016 There are many ways to measure the accomplishments of a scientist, such as papers and books published, citations, and prestige of journals published in, but we rarely gather information that allows us to evaluate the variety of influences that individual s ... Full text Cite

Residential metal contamination and potential health risks of exposure in adobe brick houses in Potosí, Bolivia.

Journal Article Sci Total Environ · August 15, 2016 Potosí, Bolivia, is the site of centuries of historic and present-day mining of the Cerro Rico, a mountain known for its rich polymetallic deposits, and was the site of large-scale Colonial era silver refining operations. In this study, the concentrations ... Full text Open Access Link to item Cite

Stratigraphic and Earth System approaches to defining the Anthropocene

Journal Article Earth S Future · August 1, 2016 Stratigraphy provides insights into the evolution and dynamics of the Earth System over its long history. With recent developments in Earth System science, changes in Earth System dynamics can now be observed directly and projected into the near future. An ... Full text Open Access Cite

Topographic variability and the influence of soil erosion on the carbon cycle

Journal Article Global Biogeochemical Cycles · May 1, 2016 Soil erosion, particularly that caused by agriculture, is closely linked to the global carbon (C) cycle. There is a wide range of contrasting global estimates of how erosion alters soil-atmosphere C exchange. This can be partly attributed to limited unders ... Full text Open Access Cite

The Anthropocene: A conspicuous stratigraphical signal of anthropogenic changes in production and consumption across the biosphere

Journal Article Earth S Future · March 1, 2016 Biospheric relationships between production and consumption of biomass have been resilient to changes in the Earth system over billions of years. This relationship has increased in its complexity, from localized ecosystems predicated on anaerobic microbial ... Full text Open Access Cite

The Anthropocene is functionally and stratigraphically distinct from the Holocene.

Journal Article Science (New York, N.Y.) · January 2016 Human activity is leaving a pervasive and persistent signature on Earth. Vigorous debate continues about whether this warrants recognition as a new geologic time unit known as the Anthropocene. We review anthropogenic markers of functional changes in the E ... Full text Open Access Cite

Global nitrogen budgets in cereals: A 50-year assessment for maize, rice, and wheat production systems.

Journal Article Scientific reports · January 2016 Industrially produced N-fertilizer is essential to the production of cereals that supports current and projected human populations. We constructed a top-down global N budget for maize, rice, and wheat for a 50-year period (1961 to 2010). Cereals harvested ... Full text Open Access Cite

When did the Anthropocene begin? A mid-twentieth century boundary level is stratigraphically optimal

Journal Article Quaternary International · October 5, 2015 We evaluate the boundary of the Anthropocene geological time interval as an epoch, since it is useful to have a consistent temporal definition for this increasingly used unit, whether the presently informal term is eventually formalized or not. Of the thre ... Full text Cite

Geophysical imaging reveals topographic stress control of bedrock weathering.

Journal Article Science (New York, N.Y.) · October 2015 Bedrock fracture systems facilitate weathering, allowing fresh mineral surfaces to interact with corrosive waters and biota from Earth's surface, while simultaneously promoting drainage of chemically equilibrated fluids. We show that topographic perturbati ... Full text Open Access Cite

Colonization of the Americas, ‘little ice age’ climate, and bombproduced carbon: Their role in defining the anthropocene

Journal Article Anthropocene Review · August 1, 2015 A recently published analysis by Lewis and Maslin (Lewis SL and Maslin MA (2015) Defining the Anthropocene. Nature 519: 171-180) has identified two new potential horizons for the Holocene-Anthropocene boundary: 1610 (associated with European colonization o ... Full text Cite

Soil in the Anthropocene

Conference Iop Conference Series Earth and Environmental Science · July 17, 2015 With scholars deliberating a new name for our geologic epoch, i.e., the Anthropocene, soil scientists whether biologists, chemists, or physicists are documenting significant changes accruing in a majority of Earth's soils. Such global soil changes interact ... Full text Cite

Mercury hair levels and factors that influence exposure for residents of Huancavelica, Peru.

Journal Article Environ Geochem Health · June 2015 Between 1564 and 1810, nearly 17,000 metric tons of mercury (Hg) vapor was released to the environment during cinnabar refining in the small town of Huancavelica, Peru. The present study characterizes individual exposure to mercury using total and speciate ... Full text Link to item Cite

'One physical system': Tansley's ecosystem as Earth's critical zone.

Journal Article The New phytologist · May 2015 Integrative concepts of the biosphere, ecosystem, biogeocenosis and, recently, Earth's critical zone embrace scientific disciplines that link matter, energy and organisms in a systems-level understanding of our remarkable planet. Here, we assert the congru ... Full text Open Access Cite

Inter-laboratory variation in the chemical analysis of acidic forest soil reference samples from eastern North America

Journal Article Ecosphere · May 1, 2015 Long-term forest soil monitoring and research often requires a comparison of laboratory data generated at different times and in different laboratories. Quantifying the uncertainty associated with these analyses is necessary to assess temporal changes in s ... Full text Cite

Diachronous beginnings of the anthropocene: The lower bounding surface of anthropogenic deposits

Journal Article Anthropocene Review · April 1, 2015 Across a large proportion of Earth’s ice-free land surfaces, a solid-phase stratigraphic boundary marks the division between humanly modified ground and natural geological deposits. At its clearest, the division takes the form of an abrupt surface at the b ... Full text Cite

Surficial gains and subsoil losses of soil carbon and nitrogen during secondary forest development.

Journal Article Global change biology · February 2015 Reforestation of formerly cultivated land is widely understood to accumulate above- and belowground detrital organic matter pools, including soil organic matter. However, during 40 years of study of reforestation in the subtropical southeastern USA, repeat ... Full text Open Access Cite

Soil carbon, multiple benefits

Journal Article Environmental Development · January 1, 2015 In March 2013, 40 leading experts from across the world gathered at a workshop, hosted by the European Commission, Directorate General Joint Research Centre, Italy, to discuss the multiple benefits of soil carbon as part of a Rapid Assessment Process (RAP) ... Full text Cite

The Role of Critical Zone Observatories in Critical Zone Science

Journal Article · January 1, 2015 The US National Science Foundation (NSF) has pioneered an integrated approach to the study of Earth's Critical Zone by supporting a network of Critical Zone Observatories (CZOs). The CZOs are intensively studied and monitored sites with a focus on a range ... Full text Cite

Residual motion mitigation in scanned carbon ion beam therapy of liver tumors using enlarged pencil beam overlap.

Journal Article Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology · November 2014 Background and purposeInterplay effects may limit the applicability of scanned ion beam therapy for moving tumors even if the motion amplitude is reduced by techniques such as gating or abdominal compression (AC). We investigate the potential of e ... Full text Cite

In memoriam: Dan Hardy Yaalon 1924-2014

Journal Article Catena · September 1, 2014 Full text Open Access Cite

Evolution of soil, ecosystem, and critical zone research at the USDA FS calhoun experimental forest

Chapter · August 1, 2014 The US Department of Agriculture (USDA) Forest Service Calhoun Experimental Forest was organized in 1947 on the southern Piedmont to engage in research that today is called restoration ecology, to improve soils, forests, and watersheds in a region that had ... Full text Cite

Benefits of soil carbon: Report on the outcomes of an international scientific committee on problems of the environment rapid assessment workshop

Journal Article Carbon Management · January 1, 2014 A Scientific Committee on Problems of the Environment Rapid Assessment (SCOPE-RAP) workshop was held on 18-22 March 2013. This workshop was hosted by the European Commission, JRC Centre at Ispra, Italy, and brought together 40 leading experts from Africa, ... Full text Cite

Current status, uncertainty and future needs in soil organic carbon monitoring.

Journal Article The Science of the total environment · January 2014 Increasing human demands on soil-derived ecosystem services requires reliable data on global soil resources for sustainable development. The soil organic carbon (SOC) pool is a key indicator of soil quality as it affects essential biological, chemical and ... Full text Cite

Measuring environmental change in forest ecosystems by repeated soil sampling: a north american perspective.

Journal Article Journal of environmental quality · May 2013 Environmental change is monitored in North America through repeated measurements of weather, stream and river flow, air and water quality, and most recently, soil properties. Some skepticism remains, however, about whether repeated soil sampling can effect ... Full text Cite

Accumulation and decay of woody detritus in a humid subtropical secondary pine forest

Journal Article Canadian Journal of Forest Research · March 1, 2013 The contribution of coarse woody detritus (CWD) to forest C budgets is poorly quantified in general, and especially so for secondary forests. This study quantifies C and N storage in logs and snags and compares the decomposition of this aboveground CWD wit ... Full text Cite

Residential mercury contamination in adobe brick homes in Huancavelica, Peru.

Journal Article PLoS One · 2013 This is the first study of adobe brick contamination anywhere in the world. Huancavelica, Peru is the site of historic cinnabar refining and one of the most mercury (Hg) contaminated urban areas in the world. Over 80% of homes in Huancavelica are construct ... Full text Link to item Cite

Coupling meteoric 10be with pedogenic losses of 9be to improve soil residence time estimates on an ancient North American interfluve

Journal Article Geology · September 1, 2012 We couple meteoric 10Be measurements with mass balance analysis of 9Be to estimate the soil residence time (SRT) of a biogeomorphically stable Ultisol in the Southern Piedmont physiographic region of the southeastern United States. We ... Full text Cite

Towards an integrated global framework to assess the impacts of land use and management change on soil carbon: Current capability and future vision

Journal Article Global Change Biology · July 1, 2012 Intergovernmental Panel on Climate Change (IPCC) Tier 1 methodologies commonly underpin project-scale carbon accounting for changes in land use and management and are used in frameworks for Life Cycle Assessment and carbon footprinting of food and energy c ... Full text Cite

The changing model of soil revisited

Journal Article Soil Science Society of America Journal · June 14, 2012 In 1961, the late Marlin G. Cline wrote a remarkable essay entitled, "The Changing Model of Soil" for the 25th Anniversary Issue of the Soil Science Society of America Proceedings. Cline was most impressed with how geomorphology was enriching pedology, and ... Full text Open Access Cite

Estimations of historical atmospheric mercury concentrations from mercury refining and present-day soil concentrations of total mercury in Huancavelica, Peru.

Journal Article Sci Total Environ · June 1, 2012 Detailed Spanish records of cinnabar mining and mercury production during the colonial period in Huancavelica, Peru were examined to estimate historical health risks to the community from exposure to elemental mercury (Hg) vapor resulting from cinnabar ref ... Full text Link to item Cite

Effects of two-century land use changes on soil iron crystallinity and accumulation in Southeastern Piedmont region, USA

Journal Article Geoderma · March 1, 2012 To evaluate effects of land use changes on iron (Fe) crystallinity in mineral soil, this study quantified labile, short-range ordered and relatively crystalline iron pools in upper mineral soils of old hardwood forests, cultivated agricultural fields, and ... Full text Cite

Effective monitoring of agriculture: a response.

Journal Article Journal of environmental monitoring : JEM · March 2012 The development of effective agricultural monitoring networks is essential to track, anticipate and manage changes in the social, economic and environmental aspects of agriculture. We welcome the perspective of Lindenmayer and Likens (J. Environ. Monit., 2 ... Full text Cite

Human-soil relations are changing rapidly: Proposals from SSSA's cross-divisional soil change working group

Journal Article Soil Science Society of America Journal · November 1, 2011 A number of scientists have named our age the Anthropocene because humanity is globally affecting Earth systems, including the soil. Global soil change raises important questions about the future of soil, the environment, and human society. Although many s ... Full text Open Access Cite

Productivity, aboveground biomass, nutrient uptake and carbon content in fast-growing tree plantations of native and introduced species in the Southern Region of Costa Rica

Journal Article Biomass and Bioenergy · May 1, 2011 Early growth performance of four native and two introduced tree species was studied during six years at 13 sites in the southern region of Costa Rica. Selected study sites represent a wide environmental gradient.The selected species were: Pinus caribaea Mo ... Full text Cite

Deep soils

Journal Article Forest Science · February 1, 2011 Although soils are a key component of the critical zone that sustains life on earth, they remain one of the least understood components of terrestrial ecosystems. Though recognized by many scientists as the most biocomplex component of the ecosystem, a gre ... Cite

Strong climate and tectonic control on plagioclase weathering in granitic terrain

Journal Article Earth and Planetary Science Letters · January 15, 2011 Investigations to understand linkages among climate, erosion and weathering are central to quantifying landscape evolution. We approach these linkages through synthesis of regolith data for granitic terrain compiled with respect to climate, geochemistry, a ... Full text Cite

Interdisciplinary sciences in a global network of critical zone observatories

Journal Article Vadose Zone Journal · January 1, 2011 This preface for the special section, Interdisciplinary Sciences in Critical Zone Observatories (CZOs), provides a brief background of the emerging Critical Zone science and its related CZOs. Highlights of 14 papers included in this special section are sum ... Full text Cite

Estimating historical atmospheric mercury concentrations from silver mining and their legacies in present-day surface soil in Potosí, Bolivia

Journal Article Atmospheric Environment · November 2010 Detailed Spanish records of mercury use and silver production during the colonial period in Potosí, Bolivia were evaluated to estimate atmospheric emissions of mercury from silver smelting. Mercury was used in the silver production process in Potosí and ne ... Full text Link to item Cite

Special report: workshop on 4D-treatment planning in actively scanned particle therapy--recommendations, technical challenges, and future research directions.

Journal Article Medical physics · September 2010 This article reports on a 4D-treatment planning workshop (4DTPW), held on 7-8 December 2009 at the Paul Scherrer Institut (PSI) in Villigen, Switzerland. The participants were all members of institutions actively involved in particle therapy delivery and r ... Full text Cite

Monitoring the world's agriculture.

Journal Article Nature · July 2010 To feed the world without further damaging the planet, Jeffrey Sachs and 24 foodsystem experts call for a global data collection and dissemination network to track the myriad impacts of different farming practices. ... Full text Cite

Guest Editorial: Saving our soils

Journal Article Frontiers in Ecology and the Environment · May 1, 2010 Full text Cite

Effects of land-use history on soil spatial heterogeneity of macro- and trace elements in the Southern Piedmont USA

Journal Article Geoderma · April 15, 2010 To quantify effects of land-use history on soil spatial heterogeneity, we sampled surficial mineral soils (0-7.5 cm depth) using a spatially-explicit design within three 0.09-ha plots in each of three ecosystems in the Southern Piedmont area of USA. The th ... Full text Cite

A simple method for estimating the influence of eroding soil profiles on atmospheric CO2

Journal Article Global Biogeochemical Cycles · April 1, 2010 Although soil erosion has often been considered a net source of atmospheric carbon (C), several recent studies suggest that erosion serves as a net C sink. We have developed a spreadsheet-based model of soil organic C dynamics within an eroding profile (So ... Full text Open Access Cite

A call to investigate drivers of soil organic matter retention vs. mineralization in a high CO2 world

Journal Article Soil Biology and Biochemistry · April 1, 2010 Understanding how elevated atmospheric CO2 alters the formation and decomposition of soil organic carbon (SOC) is important but challenging. If elevated CO2 induces even small changes in rates of formation or decay of SOC, there could ... Full text Cite

Atmospheric CO2 enrichment facilitates cation release from soil.

Journal Article Ecology letters · March 2010 Atmospheric CO(2) enrichment generally stimulates plant photosynthesis and nutrient uptake, modifying the local and global cycling of bioactive elements. Although nutrient cations affect the long-term productivity and carbon balance of terrestrial ecosyste ... Full text Cite

Rates of in situ carbon mineralization in relation to land-use, microbial community and edaphic characteristics

Journal Article Soil Biology and Biochemistry · February 1, 2010 Plant-derived carbon compounds enter soils in a number of forms; two of the most abundant being leaf litter and rhizodeposition. Our knowledge concerning the predominant controls on the cycling of leaf litter far outweighs that for rhizodeposition even tho ... Full text Cite

Restoring restoration: Removal of the invasive plant Microstegium vimineum from a North Carolina wetland

Journal Article Biological Invasions · January 1, 2010 Restoration sites are vulnerable to plant invasions due to habitat and resource alteration. We conducted an invasive plant-removal study at a wetland restoration in the North Carolina Piedmont, a site dominated by the non-native invasive, Microstegium vimi ... Full text Cite

Saving our soils

Journal Article Frontiers in Ecology and Environment · 2010 Cite

Good Wood Energy

Journal Article News & Observer OP-ED · 2010 Link to item Cite

Will Duke twice become a leader in renewable energy?

Journal Article Duke Chronicle OP-ED · 2010 Link to item Cite

Extending rotation age for carbon sequestration: A cross-protocol comparison of North American forest offsets

Journal Article Forest Ecology and Management · December 15, 2009 Through carbon offset programs, forest owners can be offered financial incentives to enhance the uptake and storage of carbon on their lands. The amount of carbon that can be claimed by an individual landowner will ultimately depend on multiple factors, in ... Full text Cite

Environment. Monitoring Earth's critical zone.

Journal Article Science (New York, N.Y.) · November 2009 Full text Cite

A virtual "field test" of forest management carbon offset protocols: The influence of accounting

Journal Article Mitigation and Adaptation Strategies for Global Change · August 18, 2009 Of the greenhouse gas (GHG) mitigation options available from U.S. forests and agricultural lands, forest management presents amongst the lowest cost and highest volume opportunities. A number of carbon (C) accounting schemes or protocols have recently eme ... Full text Cite

Resource policy. Wood energy in America.

Journal Article Science (New York, N.Y.) · March 2009 Full text Cite

Rekindling Wood Energy in America

Journal Article RenewableEnergyWorld.COM · 2009 Cite

The accrual of land use history in Utah's forest carbon cycle

Journal Article Environmental History · January 1, 2009 The out-of-control global carbon cycle is driven not only by greenhouse gas emissions from fossil-fuel combustion but also from accelerated carbon cycling through human-impacted ecosystems. Here I estimate that forests in Utah are currently accumulating at ... Full text Cite

Four-decade responses of soil trace elements to an aggrading old-field forest: B, Mn, Zn, Cu, and Fe.

Journal Article Ecology · October 2008 In the ancient and acidic Ultisol soils of the Southern Piedmont, USA, we studied changes in trace element biogeochemistry over four decades, a period during which formerly cultivated cotton fields were planted with pine seedlings that grew into mature for ... Full text Open Access Cite

Rhizogenic Fe-C redox cycling: A hypothetical biogeochemical mechanism that drives crustal weathering in upland soils

Journal Article Biogeochemistry · February 1, 2008 Field-scale observations of two upland soils derived from contrasting granite and basalt bedrocks are presented to hypothesize that redox activity of rhizospheres exerts substantial effects on mineral dissolution and colloidal translocation in many upland ... Full text Cite

Global soil change: why long-term soil-ecosystem experiments need to work harder.

Journal Article Frontiers in Ecology and Evolution · 2008 Cite

Strengthening the world’s long-term soil research base.

Journal Article International Union of Soil Science Bulletin · 2008 Open Access Cite

World's long-term soils research base supported by workshop

Journal Article Elements · January 1, 2008 Cite

Improved speciation of dissolved organic nitrogen in natural waters: amide hydrolysis with fluorescence derivatization.

Journal Article Journal of environmental sciences (China) · January 2008 The objective of this study was to improve primary-amine nitrogen (1 degree-N) quantification in dissolved organic matter (DOM) originating from natural waters where inorganic forms of N, which may cause analytical interference, are commonly encountered. E ... Full text Cite

Building critical zone research cyberinfrastructure

Journal Article Eos · December 11, 2007 Full text Cite

Preface

Journal Article Revista Mexicana De Ciencias Geologicas · December 1, 2007 Cite

Humanity's transformation of earth's soil: Pedology's new frontier

Journal Article Soil Science · December 1, 2007 Pedology was born in the 18th and 19th centuries, when soil was first conceived as a natural body worthy of its own scientific investigation. For well over a century, pedology explored soil as a system developed from a complex of natural processes. By the ... Full text Open Access Cite

Did elevated atmospheric CO2 alter soil mineral weathering?: An analysis of 5-year soil water chemistry data at Duke FACE study

Journal Article Global Change Biology · December 1, 2007 A principal driver of biogeochemical weathering of the Earth's crust is soil CO2, produced mainly by plant roots and soil heterotrophs, a water-soluble gas that forms carbonic acid which reacts with soil minerals via cation exchange and mineral ... Full text Cite

The Rhizosphere and Soil Formation

Journal Article · December 1, 2007 This chapter discusses rhizospheres and some of their broad biological, physical, and chemical effects on soil formation. By most accounts, the rhizosphere is narrowly conceived in space and time. Plant roots that are rhizospheres are networks within the b ... Full text Cite

Preface

Journal Article Revista Mexicana De Ciencias Geologicas · August 28, 2007 Cite

Early growth performance of native and introduced fast growing tree species in wet to sub-humid climates of the Southern region of Costa Rica

Journal Article Forest Ecology and Management · April 30, 2007 Early growth performance of six native and two introduced tree species was studied for seven years at 16 sites in the Southern region of Costa Rica. Selected study sites represent a wide environmental gradient that ranges from acid low fertility soils such ... Full text Cite

Long-term soil experiments: Keys to managing Earth's rapidly chancing ecosystems

Journal Article Soil Science Society of America Journal · March 1, 2007 To meet economic and environmental demands for about 10 billion people by the mid-21st century, humanity will be challenged to double food production from the Earth's soil and diminish adverse effects of soil management on the wider environment. To meet th ... Full text Cite

Preface

Journal Article Revista Mexicana de Ciencias Geologicas · 2007 Cite

Preface

Journal Article Revista Mexicana de Ciencias Geologicas · 2007 Cite

Coupling between biota and earth materials in the critical zone

Journal Article Elements · January 1, 2007 The surface of our planet is the result of billions of years of feedback between biota and Earth materials. The chemical weathering of soils and the resulting stream and ocean chemistry bear the signature of the biological world. Physical shaping of the Ea ... Full text Cite

Bioavailability of slowly cycling soil phosphorus: major restructuring of soil P fractions over four decades in an aggrading forest.

Journal Article Oecologia · November 2006 Although low solubility and slow cycling control P circulation in a wide range of ecosystems, most studies that evaluate bioavailability of soil P use only indices of short-term supply. The objective here is to quantify changes in P fractions in an Ultisol ... Full text Cite

Carbon cycling in a loblolly pine forest: Implications for the missing carbon sink and for the concept of soil

Chapter · August 23, 2006 Understanding whether regional forests are net carbon (C) sources or sinks in relation to the global cycle can only be improved by better quantification of C dynamics in specific forests. This chapter examines the C cycle in a pine forest with special atte ... Full text Cite

Succession-driven changes in soil respiration following fire in black spruce stands of interior Alaska

Journal Article Biogeochemistry · August 1, 2006 Boreal forests are highly susceptible to wildfire, and post-fire changes in soil temperature and moisture have the potential to transform large areas of the landscape from a net sink to a net source of carbon (C). Understanding the ecological controls that ... Full text Cite

Changes in stable isotopic signatures of soil nitrogen and carbon during 40 years of forest development.

Journal Article Oecologia · June 2006 Understanding what governs patterns of soil delta15N and delta13C is limited by the absence of these data assembled throughout the development of individual ecosystems. These patterns are important because stable isotopes of soil organic N and C are integr ... Full text Cite

Long-term land-use effects on soil invertebrate communities in Southern Piedmont soils, USA

Journal Article European Journal of Soil Biology · January 1, 2006 Historically, a large percentage of land area in the Piedmont of the southeastern USA was under intensive agricultural management for the production of cotton. This intensive farming resulted in massive erosion, and general degradation of soil resources un ... Full text Cite

Elemental translocation and loss from three highly weathered soil-bedrock profiles in the southeastern United States

Journal Article Geoderma · May 1, 2005 Chemical weathering of soils and rocks during pedogenesis is significant because it provides many essential elements for life and because it is coupled with the rise and fall of atmospheric CO2. We used geochemical mass-balance equations to quan ... Full text Cite

Economic and ecological impacts of wood chip production in North Carolina: An integrated assessment and subsequent applications

Journal Article Forest Policy and Economics · February 1, 2005 The North Carolina Wood Chip Mill Study represents an integrated assessment of the economic and ecological impacts associated with production of wood chips at satellite chip mills in the state of North Carolina (NC), USA. Mandated by the Governor of NC, th ... Full text Cite

What regulates soil CO2 concentrations? A modeling approach to CO2 diffusion in deep soil profiles

Journal Article Environmental Engineering Science · January 1, 2005 About 10% of the CO2 in the above-ground atmosphere is annually recycled back to the atmosphere from the soil. Soil respiration (the sum of root and microbial respiration) increases soil CO2 concentrations by 10- to 100-fold or more t ... Full text Cite

Soil acidification induced by elevated atmospheric CO2

Journal Article Global Change Biology · November 1, 2004 Soil acidification is a very important process in the functioning of earth's ecosystems. A major source of soil acidity is C02, derived from the respiration of plant roots and microbes, which forms carbonic acid in soil waters.Because elevated a ... Full text Cite

Temporal changes in the Yadkin river flow versus suspended sediment concentration relationship

Journal Article Journal of the American Water Resources Association · January 1, 2004 Dynamic linear models (DLM) and seasonal trend decomposition (STL) using local regression, or LOESS, were used to analyze the 50-year time series of suspended sediment concentra-tions for the Yadkin River, measured at the U.S. Geological Survey station at ... Full text Cite

Forest certification of state and university lands in North Carolina: A comparison

Journal Article Journal of Forestry · December 1, 2003 North Carolina State University, Duke University, and the North Carolina Division of Forest Resources (DFR) recently received both Forest Stewardship Council (FSC) and Sustainable Forestry Initiative (SFI) certification for their forests. Meeting SFI stand ... Cite

Exposure to an enriched CO2 atmosphere alters carbon assimilation and allocation in a pine forest ecosystem

Journal Article Global Change Biology · October 1, 2003 We linked a leaf-level CO2 assimilation model with a model that accounts for light attenuation in the canopy and measurements of sap-flux-based canopy conductance into a new canopy conductance-constrained carbon assimilation (4C-A) model. We est ... Full text Cite

Effects of changing organic matter inputs on labile soil iron and aluminum oxides.

Conference ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY · September 1, 2003 Link to item Cite

Determination of dissolved organic nitrogen speciation in soil extractions

Conference ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY · March 1, 2003 Link to item Cite

Impact of source organic carbon composition on soil organic matter cycling

Conference ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY · March 1, 2003 Link to item Cite

Seasonal and decadal patterns of soil carbon uptake and emission along an age sequence of burned black spruce stands in interior Alaska

Journal Article Journal of Geophysical Research Atmospheres · January 16, 2003 Postfire changes in the local energy balance and soil chemistry may significantly alter rates of carbon turnover in organic-rich soils of boreal forests. This study combines field measurements of soil carbon uptake and emission along a 140-year chronoseque ... Full text Cite

The nitrogen budget of a pine forest under free air CO2 enrichment.

Journal Article Oecologia · August 2002 Elevated concentrations of atmospheric CO2 increase plant biomass, net primary production (NPP) and plant demand for nitrogen (N). The demand for N set by rapid plant growth under elevated CO2 could be met by increasing soil N availab ... Full text Cite

Environmental controls on soil CO2 flux following fire in black spruce, white spruce, and aspen stands of interior Alaska

Journal Article Canadian Journal of Forest Research · January 1, 2002 Boreal forests contain large amounts of stored soil carbon and are susceptible to periodic disturbance by wildfire. This study evaluates the relationship between post-fire changes in soil temperature, moisture, and CO2 exchange in paired burned ... Full text Cite

Modeling in-situ pine root decomposition using data from a 60-year chronosequence

Journal Article Canadian Journal of Forest Research · January 1, 2002 Because the root system of a mature pine tree typically accounts for 20-30% of the total tree biomass, decomposition of large lateral roots and taproots following forest harvest and re-establishment potentially impact nutrient supply and carbon sequestrati ... Full text Cite

Properties of advanced weathering-stage soils in tropical forests and pastures

Journal Article Soil Science Society of America Journal · January 1, 2002 Effects of tropical forest conversion to nonforest uses greatly affects low-activity soils with substantial variable charge, but quantitative changes are poorly studied. We evaluated forest conversion effects on Ultisols and Oxisols by establishing a spati ... Full text Cite

Dynamics of sediment discharge in relation to land-use and hydro-climatology in a humid tropical watershed in Costa Rica

Journal Article Journal of Hydrology · November 15, 2001 Hydrology in humid tropical regions is often characterized by considerable natural variability and uncertainty. Hydrologic and land-use data from the Terraba basin in Costa Rica are used to analyze dynamics in sediment discharge processes during the period ... Full text Cite

The age of fine-root carbon in three forests of the eastern United States measured by radiocarbon.

Journal Article Oecologia · November 2001 Using a new approach involving one-time measurements of radiocarbon (14C) in fine (<2 mm diameter) root tissues we have directly measured the mean age of fine-root carbon. We find that the carbon making up the standing stock of fine roots in dec ... Full text Cite

Spatial patterns of suspended sediment yields in a humid tropical watershed in Costa Rica

Journal Article Hydrological Processes · August 30, 2001 Humid tropical regions are often characterized by extreme variability of fluvial processes. The Rio Terraba drains the largest river basin, covering 4767 km2, in Costa Rica. Mean annual rainfall is 3139 ± 419sd mm and mean annual disc ... Full text Cite

Meeting Global Policy Commitments: Carbon Sequestration and Southern Pine Forests

Journal Article Journal of Forestry · April 1, 2001 In managed forests, the amount of carbon further sequestered will be determined by (1) the increased amount of carbon in standing biomass (resulting from land-use changes and increased productivity); (2) the amount of recalcitrant carbon remaining below gr ... Cite

Biogeochemical models relating soil nitrogen losses to plant-available N

Journal Article Environmental Engineering Science · January 1, 2001 Four biogeochemical models that simulate N cycling in the plant-soil-water-atmosphere environment are evaluated. Each model considers N inputs and outputs to an agricultural system with emphasis on the relationships between mineral fertilizers and bioferti ... Full text Cite

Sensitivity of soil methane fluxes to reduced precipitation in boreal forest soils

Journal Article Soil Biology and Biochemistry · September 18, 2000 In order to better predict soil sinks of methane, we need to examine soil methane flux patterns and responses to altered soil moisture regimes. Estimates of the global atmospheric CH4 budget must also account for fluxes in the vast boreal region ... Full text Cite

Dynamic modeling of long-term sedimentation in the Yadkin River basin

Journal Article Advances in Water Resources · July 1, 2000 Modeling of sediment transport in relation to changing land-surface conditions against a background of considerable natural variability is a challenging area in hydrology. Bayesian dynamic linear models (DLMs) however, offer opportunities to account for no ... Full text Cite

Long-term soil potassium availability from a Kanhapludult to an aggrading loblolly pine ecosystem

Journal Article Forest Ecology and Management · May 1, 2000 A long-term (1962 to 1990) forest biogeochemistry study in the southeastern Piedmont of the USA provided estimates of soil K release in response to forest regrowth. We investigated the sources of soil K that buffered the exchangeable K pools during forest ... Full text Cite

Nitrogen inhibition of nodulation and N2 fixation of a tropical N2-fixing tree (Gliricidia sepium) grown in elevated atmospheric CO2

Journal Article New Phytologist · February 1, 2000 Interactive effects of elevated atmospheric CO2 and soil N availability on N2 fixation and biomass production were examined using Gliricidia sepium, a tropical leguminous tree species. Our objective was to determine if elevated CO Full text Cite

Effects of free-air CO2 enrichment (FACE) on belowground processes in a Pinus taeda forest

Journal Article Ecological Applications · January 1, 2000 Terrestrial vegetation and soils may act as important carbon sinks if rising atmospheric CO2 stimulates plant production. We used free-air CO2 enrichment (FACE) technology to expose three 30 m diameter plots of a loblolly pine (Pinus ... Full text Cite

Legacies of agriculture and forest regrowth in the nitrogen of old-field soils

Journal Article Forest Ecology and Management · 2000 Cite

Throughfall chemistry in a loblolly pine plantation under elevated atmospheric CO2 concentrations

Journal Article Biogeochemistry · January 1, 2000 Accelerated tree growth under elevated atmospheric CO2 concentrations may influence nutrient cycling in forests by (i) increasing the total leaf area, (ii) increasing the supply of soluble carbohydrate in leaf tissue, and (iii) increasing nutrie ... Full text Cite

A re-examination of exchangeable acidity as extracted by potassium chloride and potassium fluoride

Journal Article Communications in Soil Science and Plant Analysis · January 1, 2000 In order to better understand some of the factors likely to affect measurements of KCl extractable acidity, experiments were conducted using synthetic solutions and extracts from a wide range of contrasting soils. The reagents used for measuring exchangeab ... Full text Cite

Rapid accumulation and turnover of soil carbon in a re-establishing forest

Journal Article Nature · July 1, 1999 Present understanding of the global carbon cycle is limited by uncertainty over soil-carbon dynamics. The clearing of the world's forests, mainly for agricultural uses, releases large amounts of carbon to the atmosphere (up to 2 x 1015 gyr- ... Full text Cite

Three decades of observed soil acidification in the Calhoun experimental forest: Has acid rain made a difference?

Journal Article Soil Science Society of America Journal · January 1, 1998 Three decades of repeated soil sampling from eight permanent plots at the Calhoun Experimental Forest in South Carolina allowed us to estimate the rate of soil acidification, the chemical changes in the soil exchange complex, and the natural and anthropoge ... Full text Cite

Soil carbon dioxide fluxes and profile concentrations in two boreal forests

Journal Article Canadian Journal of Forest Research · January 1, 1998 Because a large fraction of the world's carbon exists in the soil of boreal forests, understanding how soil temperature and moisture affect soil respiration is vital for predicting soil response to climate change. We measured soil respiration and CO2< ... Full text Cite

The bio in aluminum and silicon geochemistry

Journal Article Biogeochemistry · January 1, 1998 The translocation and transformation of Al and Si are of paramount importance in the processes of primary-mineral weathering, saprolite formation and soil formation. Geochemical mass balance studies of these processes have often not considered the importan ... Full text Cite

Simulating trends in soil organic carbon in long-term experiments using the century model

Journal Article Geoderma · December 1, 1997 This paper describes Century Soil Organic Matter (SOM) Model simulations of seven long-term data sets that are the subject of this special issue. We found that Century successfully simulates SOM C across a variety of land use and climate types. Simulations ... Full text Cite

Simulating trends in soil organic carbon in long-term experiments using the CANDY model

Journal Article Geoderma · December 1, 1997 CANDY (CArbon and Nitrogen DYnamics) is a simulation system based on long-term experiments of organic matter turnover and nitrogen dynamics at Bad Lauchstadt, Germany. Key driving variables are soil physical properties, meteorological data and management i ... Full text Cite

Simulating trends in soil organic carbon in long-term experiments using RothC-26.3

Journal Article Geoderma · December 1, 1997 As part of a model evaluation exercise, RothC-26.3, a model for the turnover of organic carbon in non-waterlogged soils, was fitted to measurements of organic carbon from 18 different experimental treatments on 6 long-term experimental sites in Germany, En ... Full text Cite

Simulating trends in soil organic carbon in long-term experiments using the NCSOIL and NCSWAP models

Journal Article Geoderma · December 1, 1997 NCSOIL simulates C and N transformations in 4 soil organic pools: Pool I labile, Pool I resistant, Pool II, and Pool III, with half-lives of 2, 17, 115 days and about 150 years, respectively. Pool I labile and Pool I resistant represent the microbial bioma ... Full text Cite

Simulating trends of soil organic carbon in seven long-term experiments using the SOMM model of the humus types

Journal Article Geoderma · December 1, 1997 Using the SOMM model of the humus types (Mor, Moder, Mull), simulations of SOM dynamics at seven long-term experiments were attempted as a part of a model evaluation exercise. The model comprises three compartments (undecomposed litter, partially humified ... Full text Cite

Simulating trends in soil organic carbon in long-term experiments using the ITE (Edinburgh) Forest and Hurley Pasture ecosystem models

Journal Article Geoderma · December 1, 1997 Models are used increasingly to predict long-term changes in soil organic matter (SOM). Comparison with measured data is clearly desirable. We compared simulations of the mechanistic ITE (Edinburgh) Forest (EF) and Hurley Pasture (HP) ecosystem models with ... Full text Cite

Growth, foliar and nutrient status of Terminalia amazonia planted in southwestern Costa Rica

Journal Article Journal of Tropical Forest Science · December 1, 1997 A study was conducted to examine the growth of Terminalia amazonia, a promising plantation species native to the humid neotropics, in relation to soil and foliar nutrient levels, its nutrient requirements and suitable management practices, and to suggest f ... Cite

Ecological and economic analysis of watershed protection in Eastern Madagascar

Journal Article Journal of Environmental Management · January 1, 1997 Watershed protection is one of the many goods and services provided by the world's fast disappearing tropical forests. Among the variety of watershed protection benefits, flood damage alleviation is crucial, particularly in upland watersheds. This study is ... Full text Cite

Design and Use of Background-Reduced 27Al NMR Probes for the Study of Dilute Samples from the Environment

Journal Article Applied Spectroscopy · February 1, 1995 Development of methods for the detection and measurement of aluminum (Al) is crucial for our understanding of Al(III) chemistry and toxicity in natural waters, soil solutions, and environmental samples. Traditional colorimetric assays, by their very nature ... Full text Cite

Nitrate in groundwaters of the Central Valley, Costa Rica

Journal Article Environment International · 1995 Cite

How deep is soil?

Journal Article Bioscience · January 1, 1995 Full text Cite

Speciation of aqueous mononuclear Al(III)-hydroxo and other Al(III) complexes at concentrations of geochemical relevance by aluminum-27 nuclear magnetic resonance spectroscopy

Journal Article Geochimica Et Cosmochimica Acta · January 1, 1995 Aluminum-27 (27Al) nuclear magnetic resonance (NMR) spectroscopy was used to characterize Al(III)-hydroxo complexes, in aqueous solutions with total Al(III) concentrations of 1.0-10 μM, using a custom-built NMR probe, coil, and sample bottle wit ... Full text Cite

Carbon cycling in a loblolly pine forest: implications for the missing carbon sink and for the concept of soil

Journal Article Carbon Forms and Functions in Forest Soils · January 1, 1995 During the 34 yr of forest regrowth, ecosystem C increased by 175.5 Mg/ha, averaging 5.16 Mg ha-1 yr-1. Nearly all (>98%) of this C accumulated in plant biomass and forest floor, with <2% of newly accumulated C stored in the surficial ... Cite

Soil carbon turnover in a recovering temperate forest

Journal Article Global Biogeochemical Cycles · January 1, 1995 Soil radiocarbon measurements show that mineral soil carbon under a recovering temperate forest in South Carolina turns over twice as fast as carbon in undisturbed soil. The observed 12‐year turnover time influences the design and interpretation of CO ... Full text Cite

Nitrate in groundwaters of the Central Valley, Costa Rica

Journal Article Environment International · January 1, 1995 Nitrate contamination of ground water under agricultural areas is a well recognized environmental problem, yet few reports describe the problem in tropical regions. This study evaluated concentrations of NO3-N in shallow aquifers used to provide ... Full text Cite

Environmental impacts of nitrification and nitrate adsorption in fertilized andisols in the Valle Central of Costa Rica

Journal Article Soil Science · January 1, 1994 A major scientific challenge for modern agriculture is control of off-site effects on the water resource. In the Valle Central of Costa Rica, coffee plantations may leach fertilizer-derived (Equation presented) to groundwaters, as a result of high fertiliz ... Full text Cite

Sulfate adsorption in forest soils of the Great Lakes region

Journal Article Soil Science Society of America Journal · January 1, 1994 Full text Cite

Use of edaphic variables to control experimental error: A case study on blocking and use of covariance

Journal Article Soil Science · January 1, 1993 Field studies that extend over large areas are commonly blocked in an attempt to minimize experimental error. In an experiment that was designed to determine the effects of exposure to acidic rain and ozone on seedling loblolly pines through three years of ... Full text Cite

Soil chemistry in a loblolly/longleaf pine forest with interval burning

Journal Article Ecological Applications · January 1, 1992 Examined the 30-yr cumulative effects of prescribed fires at intervals of 1, 2, 3, and 4 yr in a loblolly Pinus taeda and longleaf pine Pinus palustris forest in the Coastal Plain of South Carolina. The fine fraction of the forest floor contained much more ... Full text Cite

Ion leaching in forest ecosystems along a great lakes air pollution gradient

Journal Article Journal of Environmental Quality · January 1, 1992 A gradient of H+, SO4/2-, and NO3/- deposition across the Great Lakes region raised concerns over impacts on soil solution chemistry and ion leaching in regional forest ecosystems. Ten study sites repr ... Full text Cite

Nitrogen dynamics and growth of seedlings of an N-fixing tree (Gliricidia sepium (Jacq.) Walp.) exposed to elevated atmospheric carbon dioxide.

Journal Article Oecologia · November 1991 Seeds of Gliricidia sepium (Jacq.) Walp., a tree native to seasonal tropical forests of Central America, were inoculated with N-fixing Rhizobium bacteria and grown in growth chambers for 71 days to investigate interactive effects of atmospheric CO2 Full text Cite

Transport of metal cations through a nutrient-poor forest ecosystem

Journal Article Water Air and Soil Pollution · August 1, 1991 Metal cations were analyzed in bulk precipitation, soil water, and stream flow in a southeastern U.S. lower Coastal Plain pine flatwoods for 6 yr. Extractable ions in mineral soil and total amounts in herbaceous vegetation were also determined. Concentrati ... Full text Cite

Soil Diversity in the Tropics

Journal Article Advances in Ecological Research · January 1, 1991 This chapter reviews the soil diversity in the tropics. Soil diversity in the tropics is relatively easy to demonstrate using maps with scales of 1.5 million. This chapter evaluates common misconceptions about “tropical soil” that are of ecological signifi ... Full text Cite

Effects of annual tillage on organic carbon in a fine-textured udalf: The importance of root dynamics to soil carbon storage

Journal Article Soil Science · January 1, 1990 Seven years of annual tillage of a fine-textured Hapludalf, cleared of forest about 160 yr ago and more recently cropped for hay, caused grasses to be replaced by annual herbs. Tillage decreased carbon (C) stored in the surface meter of soil, mainly be alt ... Full text Cite

Moisture and nutrient status of extremely acid Umbrepts in the Black Mountains of North Carolina

Journal Article Soil Science Society of America Journal · January 1, 1989 Moisture and nutrient conditions are poorly characterized in soils at elevations > 1500 m in the southern Appalachian Mountains. In the Black Mountains, high elevation soils are Typic and Lithic Haplumbrepts, with umbric epipedons that are extremely acid, ... Full text Cite

Correlations between extractable Na, K, Mg, Ca, P & N from fresh and dried samples of two Aquults

Journal Article Journal of Soil Science · January 1, 1988 Significant increases in extractable ions resulted from air‐drying and grinding samples of two infertile Aquults. Effects of the sample preparation differed markedly between ions and between the two soils. Regression equations were calculated to predict ex ... Full text Cite

Wet deposition estimates from long-term bulk and event wet-only samples of incident precipitation and throughfall

Journal Article Journal of Environmental Quality · January 1, 1988 This report describes a 2-yr study comparing two sampling systems that are used to measure major ionic constituents in incident precipitation and canopy throughfall: long-term bulk sampling vs. event-based, wet-only sampling. Major deviations in chemical c ... Full text Cite

EFFECTS OF LOW IONIC STRENGTH SOLUTIONS ON pH OF ACID FORESTED SOILS.

Journal Article Soil Science Society of America Journal · January 1, 1988 'Salt effects' on soil pH are not well-documented with highly acidic soils in contact with solutions of very low ionic strength ( less than 1 mM//c/L). These dilute, acidic conditions are typical of soil solutions in many forest ecosystems. A wide range of ... Full text Cite

Growth responses of red pine seedlings to the chemical bioregulator, DCPTA

Journal Article New Forests · December 1, 1987 The chemical bioregulator, 2-(3, 4-dichlorophenoxy)-triethylamine (DCPTA), which has markedly stimulated photosynthesis, carbon allocation, and above- and below-ground growth of several agricultural crops, caused small growth effects on red pine (Pinus res ... Full text Cite

Nutrient Cycles and H+ Budgets of Forest Ecosystems

Journal Article Advances in Ecological Research · January 1, 1987 The acidity of forest soil affects a wide range of ecological processes, including the solubility and exchange reactions of inorganic nutrients and toxic metals, the activities of soil animals and microorganisms, and the weathering of soil minerals. Change ... Full text Cite

Erratum to: Sources of Acidity in Some Forested Udults (Soil Science Society of America Journal, (1986), 50, 6, (1584-1589), 10.2136/sssaj1986.03615995005000060040x)

Journal Article Soil Science Society of America Journal · November 1, 1986 In the last line of the Abstract on p. 1584, "base solution" should read "base saturation." Our apologies and thanks to Dr. Richter for bringing this to our attention. ... Full text Cite

Sulfur cycling in five forest ecosystems

Journal Article Water Air and Soil Pollution · October 1, 1986 The cycling and retention of sulfur were studied in five forest ecosystems: a chestnut oak and yellow poplar stand on Walker Branch Watershed, Tennessee; a mixed oak stand on Camp Branch Watershed, Tennessee; and a red alder and Douglas-fir stand at the Th ... Full text Cite

Atmospheric Deposition and Canopy Interactions of Major Ions in a Forest

Journal Article Science · January 1, 1986 Airborne particles and vapors contributed significantly to the nutrient requirements and the pollutant load of a mixed hardwood forest in the eastern United States. Dry deposition was an important mechanism of atmospheric input to the foliar canopy, occurr ... Full text Cite

SOURCES OF ACIDITY IN SOME FORESTED UDULTS.

Journal Article Soil Science Society of America Journal · January 1, 1986 Three sources of soil acidity (bicarbonate leaching; base-cation accumulation in aboveground wood, roots, and forest floor; and acid atmospheric deposition) were evaluated in relation to exchangeable acidity of three forested Udults in Tennessee. The Udult ... Full text Cite

Increases in extractable ions in infertile Aquults caused by sample preparation.

Journal Article Soil Science Society of America Journal · January 1, 1985 Effects of sample preparation on dilute acid-extractable ions were measured for paired unground field-fresh and ground air-dried soil samples taken from three depths at two sites in the coastal flatwoods of South Carolina. Ion releases from grinding and dr ... Full text Cite

The effects of atmospheric deposition on potassium, calcium, and magnesium cycling in two deciduous forests

Journal Article Canadian Journal of Forest Research · January 1, 1985 Sulfate was the dominant anion in throughfall and soil solutions from a chestnut oak (Quercus pinus L.) and a yellow poplar (Liriodendron tulipifera L.) forest in eastern Tennessee. Assuming much of this SO42- was of anthropogenic ori ... Full text Cite

The effects of acidic deposition on cation leaching from three deciduous forest canopies.

Journal Article Canadian Journal of Forest Research · January 1, 1985 For 3 deciduous forests in E Tennessee currently receiving wet and dry acidic deposition, retention of atmospherically deposited cations (H+ and NH+4 exceeded retention of deposited anions (NO-3) on a charge-equivalent basi ... Full text Cite

Watershed management problems in humid tropical uplands.

Journal Article Nature Resources · January 1, 1985 Unesco's Man and Biosphere Programme has studied new methods for the integrated management of watersheds in such widespread places as the southern Andes, the Himalayas, the Alps of Switzerland and Austria, and in China. The International Hydrological progr ... Cite

PHYSIOLOGICAL PROCESSES IN SOYBEAN INHIBITED BY GASEOUS POLLUTANTS BUT NOT BY ACID RAIN

Journal Article New Phytologist · January 1, 1985 The responses of several physiological processes and indices were studied in soybean plants [Glycine max (L.) Merr. cv. ‘Davis’] exposed to combinations of polluted air (0.1 μl l−1 SO2+ 0.05 μl l−1 O3) and simula ... Full text Cite

COMBINED EFFECTS OF ATMOSPHERIC DEPOSITION, INTERNAL ACID PRODUCTION, AND HARVESTING ON NUTRIENT GAINS AND LOSSES FROM FOREST ECOSYSTEMS.

Journal Article undefined · December 1, 1984 Atmospheric deposition can cause nutrient gains (N, S) or losses (Ca, Mg, K) from forest ecosystems whereas harvesting causes only losses. S deposition in polluted regions exceeds S export via whole-tree harvesting, but this is not normally the case for N. ... Cite

Combined effects of atmospheric deposition, internal acid production, and harvesting on nutrient gains and losses from forest ecosystems.

Journal Article · December 1, 1984 Atmospheric deposition can cause nutrient gains (N, S) or losses (Ca, Mg, K) from forest ecosystems, whereas harvesting causes only losses. S deposition in polluted regions greatly exceeds S export via whole-tree harvesting, but this is not normally the ca ... Cite

Combined effects of atmospheric deposition, internal acid production, and harvesting on nutrient gains and losses from forest ecosystems.

Journal Article undefined · January 1, 1984 Atmospheric deposition can cause nutrient gains (N, S) or losses (Ca, Mg, K) from forest ecosystems, whereas harvesting causes only losses. S deposition in polluted regions greatly exceeds S export via whole-tree harvesting, but this is not normally the ca ... Cite

Effects of atmospheric deposition on forest nutrient cycles

Journal Article Tappi Journal · January 1, 1984 Atmospheric depositions of nitrogen, sulfur, and hydrogen ion have probably increased over the last few decades in many parts of the world. Because most forests are deficient in nitrogen, such increases can be beneficial. Little is known about the changes ... Cite

Effects of acid precipitation and natural processes on cation leaching from 4 diverse forest ecosystems.

Journal Article · December 1, 1983 Two forest ecosystems in eastern Tennessee and 2 in western Washington with a history of intensive nutrient cycling research were selected for studies on the effects or acid precipitation and natural acid production processes on cation leaching rates. At t ... Cite

CONTRIBUTIONS OF ACID DEPOSITION AND NATURAL PROCESSES TO CATION LEACHING FROM FOREST SOILS: A REVIEW.

Journal Article Proceedings Annual Meeting Air Pollution Control Association · December 1, 1983 Cite

Effects of acid precipitation and natural processes on cation leaching from 4 diverse forest ecosystems.

Journal Article undefined · January 1, 1983 Two forest ecosystems in eastern Tennessee and 2 in western Washington with a history of intensive nutrient cycling research were selected for studies on the effects or acid precipitation and natural acid production processes on cation leaching rates. At t ... Cite

Determination of inorganic sulfate in foliage with barium chloranilate

Journal Article Soil Science Society of America Journal · January 1, 1983 Foliage samples were extracted in 0. 01M HCl at room temperature and extracts analyzed indirectly for sulfate (SO**2//4** minus ) with a barium chloranilate procedure. The method was tested with foliage of coniferous and deciduous tree species, and sulfate ... Full text Cite

Chemical composition and spatial variation of bulk precipitation at a coastal plain watershed in South Carolina

Journal Article Water Resources Research · January 1, 1983 Bulk precipitation was collected for analysis of ionic constituents at eight rainfall stations over a 4‐year period at a 500‐ha watershed in the Lower Coastal Plain of South Carolina. Mean annual deposition rates of ions in greatest supply, Cl−, ... Full text Cite

Contributions of acid deposition and natural processes to cation leaching from forest soils: a review

Journal Article Journal of the Air Pollution Control Association · January 1, 1983 Methods of quantifying the roles of atmospheric acid inputs and internal acid generation by carbonic, organic, and nitric acids are illustrated by reviewing data sets from several intensively studied sites in North America. Some of the sites (tropical, tem ... Full text Cite

Atmospheric sulfur deposition, neutralization, and ion leaching in two deciduous forest ecosystems

Journal Article Journal of Environmental Quality · January 1, 1983 In the 1981 water year, bulk precipitation was primarily a solution of dilute H2SO4, and SO42- was the dominant anion in throughfall and soil leachates in two eastern Tennessee deciduous forests. Ecosystem inputs ... Full text Cite

EFFECTS OF ATMOSPHERIC DEPOSITION ON FOREST NUTRIENT CYCLES.

Journal Article Annual Meeting Technical Association of the Pulp and Paper Industry · January 1, 1983 Cite

EFFECTS OF ACID RAIN ON FOREST SOIL CHANGE.

Journal Article APCA Specialty Conference Proceedings SP · December 1, 1982 Cite

Cycling of organic and inorganic sulphur in a chestnut oak forest

Journal Article Oecologia · August 1, 1982 Sulfur (S) cycling in a chestnut oak forest on Walker Branch Watershed, Tennessee, was dominated by geochemical processes involving sulfate. Even though available SO42-was present far in excess of forest nutritional requirements, the ... Full text Cite

Prescribed fire: effects on water quality and forest nutrient cycling.

Journal Article Science (New York, N.Y.) · February 1982 Prescribed fire, a practice applied annually to about 10(6) hectares of forests in the southeastern United States, had limited effects on soils, nutrient cycling, and hydrologic systems of a coastal plain pine forest. Hydrologic fluxes of nitrogen, phospho ... Full text Cite

A technique for determining quantitative expressions of dormancy in seeds

Journal Article Annals of Botany · January 1, 1982 A method of quantifying the heterogeneity of dormancy within seed populations is described. The method compares germination responses of unstratified and stratified seeds of Pinus taeda L. (loblolly pine). Mathematical functions were fitted to cumulative g ... Full text Cite

Identification of lower coastal plain sites of low soil fertility.

Journal Article Southern Journal of Applied Forestry · January 1, 1980 Analysis of forest survey plot data for 16 coastal counties in North Carolina indicated substantial areas of very low productivity for pine growth were associated with two site types, savannas and pocosins, that are easily identified by aerial photo interp ... Full text Cite