Scholars@Duke
James F. Reynolds

James F. Reynolds

Professor Emeritus
Environmental Sciences and Policy
james.f.reynolds@duke.edu
Duke Box 90338, Durham, NC 27708-0338
130 Science Dr., Biological Sciences Bldg., Rm 137-Box 90338, Durham, NC 27708

Selected Publications

Desertification

Chapter · January 1, 2024 The phenomenon of desertification involves the loss of biological or economic productivity and biodiversity in arid and semiarid croplands, pastures, rangelands, and subhumid woodlands due mainly to nonsustainable human activities, such as overcultivation, ... Full text Open Access Cite

Modeling Effects of Spatial Pattern, Drought, and Grazing on Rates of Rangeland Degradation: A Combined Markov and Cellular Automaton Approach

Chapter · January 1, 2023 The hybrid Markov-cellular automaton model simulates vegetation dynamics as a spatially and temporally discrete system. Temporal dynamics are controlled by the transition probabilities among these states, whereas spatial dynamics are controlled by local ru ... Full text Cite

Foreward

Chapter · March 16, 2022 Desertification and land degradation (DLD) are considered major global change issues. The United Nation’s Sustainable Development Goal 15 (SDG 15) contends that “desertification affects as much as one-sixth of the world's population, seventy percent of all ... Link to item Cite

Desertification is a prisoner of history: An essay on why young scientists should care

Journal Article Ecosistemas · 2021 Featured Publication Since its origins, the concept of desertification has been shrouded in controversy and ambiguity. As a result, no single definition of the term has been acceptable; there is no agreement on its extent or seriousness; and the solutions proposed are ... Full text Open Access Cite

Hydrological and ecological responses of ecosystems to extreme precipitation regimes: A test of empirical-based hypotheses with an ecosystem model

Journal Article Perspectives in Plant Ecology, Evolution and Systematics · October 1, 2016 Featured Publication Many uncertainties exist in our quest to understand and predict how terrestrial ecosystems will respond to climate change. A particularly challenging issue is how increases in extreme precipitation regimes, which are characterized by larger but fewer indiv ... Full text Open Access Cite

Biomass offsets little or none of permafrost carbon release from soils, streams, and wildfire: An expert assessment

Journal Article Environmental Research Letters · March 7, 2016 Featured Publication As the permafrost region warms, its large organic carbon pool will be increasingly vulnerable to decomposition, combustion, and hydrologic export. Models predict that some portion of this release will be offset by increased production of Arctic and boreal ... Full text Open Access Cite

Changes in evapotranspiration and phenology as consequences of shrub removal in dry forests of central Argentina

Journal Article Ecohydrology · October 1, 2015 Featured Publication More than half of the dry woodlands (forests and shrublands) of the world are in South America, mainly in Brazil and Argentina, where in the last years intense land use changes have occurred. This study evaluated how the transition from woody-dominated to ... Full text Open Access Cite

A novel approach to assess livestock management effects on biodiversity of drylands

Journal Article Ecological Indicators · January 1, 2015 Featured Publication In drylands livestock grazing is the main production activity, but overgrazing due to mismanagement is a major cause of biodiversity loss. Continuous grazing around water sources generates a radial gradient of grazing intensity called the piosphere. The ec ... Full text Open Access Cite

Earthworms modify plant biomass and nitrogen capture under conditions of soil nutrient heterogeneity and elevated atmospheric CO2 concentrations

Journal Article Soil Biology and Biochemistry. · November 2014 Featured Publication Earthworms modify the way roots respond to soil nutrient patchiness. However, few studies have evaluated the joint effects of earthworms and soil heterogeneity on plant community biomass and species dominance, and none of them have assessed the influence o ... Full text Open Access Cite

A mechanistic-bioclimatic modeling analysis of the potential impact of climate change on biomes of the Tibetan Plateau.

Journal Article Ecology · August 2014 Featured Publication The Tibetan Plateau (TP) is experiencing high rates of climatic change. We present a novel combined mechanistic-bioclimatic modeling approach to determine how changes in precipitation and temperature on the TP may impact net primary production (NPP) in fou ... Full text Open Access Cite

Soil heterogeneity modulates responses to multiple global environmental changes in model grassland communities

Chapter · March 1, 2013 An important part of ecological research has been devoted to understand and predict how plant species and assemblages respond to changes in the availability and spatiotemporal heterogeneity of resources like water, light and nutrients. In the natural world ... Cite

New Ecology Education: Preparing Students for the Complex Human- Environmental Problems of Dryland East Asia

Chapter · 2013 The book provides state-of-the-art knowledge on drylands ecosystem dynamics, climate changes, and land use in DEA. With contributions from international experts, the book will be of interest both to researchers and students. ... Cite

Desertification

Chapter · January 1, 2013 The phenomenon of desertification involves the loss of biological or economic productivity and biodiversity in arid and semiarid croplands, pastures, rangelands, and subhumid woodlands due mainly to nonsustainable human activities, such as overcultivation, ... Full text Open Access Cite

Impacts of increased variability in precipitation and air temperature on net primary productivity of the Tibetan Plateau: a modeling analysis

Journal Article Climatic Change · 2013 Featured Publication We analyzed interannual variability (IAV) of precipitation and air temperature over a 40-year period (1969-2008) for 11 sites along a precipitation gradient on the Tibetan Plateau. The observed IAV for both precipitation and air temperature decreases with ... Full text Open Access Cite

Scientific concepts for an integrated analysis of desertification

Journal Article Land Degradation and Development · 2011 Featured Publication The Global Drylands Observing System proposed in this issue should reduce the huge uncertainty about the extent of desertification and the rate at which it is changing, and provide valuable information to scientists, planners and policy-makers. However, it ... Full text Open Access Cite

Impacts of shrub encroachment on ecosystem structure and functioning: Towards a global synthesis

Journal Article Ecology Letters · 2011 Featured Publication Encroachment of woody plants into grasslands has generated considerable interest among ecologists. Syntheses of encroachment effects on ecosystem processes have been limited in extent and confined largely to pastoral land uses or particular geographical re ... Full text Open Access Cite

Coupled human-environment system approaches to desertification: Linking people to pixels

Chapter · January 1, 2009 The first part of this paper provides the rationale for approaching desertification by integrating biophysical and socio-economic data. We start with a brief overview of the causes and consequences of land degradation in global drylands, with an emphasis o ... Cite

Soil carbon stocks in experimental mesocosms are dependent on the rate of labile carbon, nitrogen and phosphorus inputs to soils

Journal Article Functional Ecology · December 1, 2008 1. The soil sink for carbon is important in regulating climate and soil fertility. The sink strength is dependent on the balance of soil carbon decomposition and formation. Variation in the rates of these processes to manipulations of resource availabiliti ... Full text Cite

Individual vs. population plastic responses to elevated CO2, nutrient availability, and heterogeneity: A microcosm experiment with co-occurring species

Journal Article Plant and Soil · July 1, 2007 We conducted an experiment to evaluate the plastic phenotypic responses of individuals, growing under intra-specific competition, and populations of three co-occurring grassland species (Lolium perenne, Plantago lanceolata, and Holcus lanatus) to joint var ... Full text Cite

Global desertification: building a science for dryland development.

Journal Article Science · May 11, 2007 Featured Publication In this millennium, global drylands face a myriad of problems that present tough research, management, and policy challenges. Recent advances in dryland development, however, together with the integrative approaches of global change and sustainability scie ... Full text Open Access Link to item Cite

Amount or pattern? Grassland responses to the heterogeneity and availability of two key resources.

Journal Article Ecology · February 2007 Patterns of resource availability and heterogeneity shape the composition, productivity, and dynamics of plant assemblages in a wide variety of terrestrial ecosystems. Despite this, the responses of plant assemblages to simultaneous changes in the availabi ... Full text Cite

Scaling terrestrial biogeochemical processes contrasting intact and model experimental systems

Journal Article · December 1, 2006 Planet Earth is undergoing enormous change, clearly discernable on time scales of decades to centuries. This is largely a result of human activities, especially the emission of greenhouse gases and pollutants, the clearing of global forests, the urbanizati ... Full text Cite

Soil heterogeneity and community composition jointly influence grassland biomass

Journal Article Journal of Vegetation Science · August 2006 Cite

Understanding global desertification: Biophysical and socioeconomic dimensions of hydrology

Chapter · January 1, 2006 Drylands are regions of the globe where the index of aridity (IA)-defined as the ratio of mean annual precipitation (P) to mean annual potential evapotranspiration (PET)-is less than 0.65 (see Chapters 1 and 8). If we restrict IA to the range of 0.05 to 0. ... Full text Cite

The interactive role of human and environmental dimensions in the desertification debate

Journal Article Annals of Arid Zone · January 1, 2003 We summarize a new synthetic framework for understanding and responding to desertification that emerged from the 88th Dahlem workshop on "An Integrated Assessment of the Ecological, Meteorological and Human Dimensions of Global Desertification". We refer t ... Cite

Gross primary productivity in duke forest: Modeling synthesis of co2 experiment and eddy-flux data

Journal Article Ecological Applications · January 1, 2001 This study was designed to estimate gross primary productivity (GPP) in the Duke Forest at both ambient and elevated CO2 (ambient + 200 μL/L) concentrations using a physiologically based canopy model. The model stratified the canopy of loblolly pine (Pinus ... Full text Cite

Responses of a loblolly pine ecosystem to CO2 enrichment: A modeling analysis

Journal Article Tree Physiology · 1999 The development of the Free-AirCO2 Enrichment (FACE) facilities represents a substantial advance in experimental technology for studying ecosystem responses to elevated CO2. A challenge arising from the application of this technology is the utilization of ... Cite

Impact of drought on desert shrubs: Effects of seasonality and degree of resource island development

Journal Article Ecological Monographs · January 1, 1999 Large areas of semiarid grasslands in the southwestern United States have been virtually replaced by shrubs during the past century. Understanding the causes and consequences of such vegetation dynamics requires that we elucidate the interplay between exte ... Full text Open Access Cite

Soil nitrogen, microbial biomass, and respiration along an arctic toposequence

Journal Article Soil Science Society of America Journal · 1998 Cite

Modularity and genericness in plant and ecosystem models

Journal Article Ecological Modeling · 1997 Cite

Modularity in plant models

Journal Article Ecological Modeling · 1997 Cite

A coordination model of whole-plant carbon allocation in relation to water stress

Journal Article Annals of Botany · January 1, 1997 Although water is an important determinant of the allocation of material between roots and shoots during growth, and often parallels the effects of nitrogen, few models have explicitly considered allocation in relation to water supply. We use coordination ... Full text Cite

Growth and root NO3/- and PO4/3- uptake capacity of three desert species in response to atmospheric CO2 enrichment

Journal Article Australian Journal of Plant Physiology · 1997 In a phytotron experiment, we examined growth and rates of NO3/- and PO4/3- uptake in seedlings of two desert C3 shrubs (Larrea trdentata and Prosopis glandulosa) and a desert C4 perennial grass (Bouteloua eriopoda) grown under CO2 partial pressures of 35 ... Cite

Introduction: modularity in plant models

Journal Article Ecological Modelling · January 1997 Full text Cite

Modelling whole-plant allocation in relation to carbon and nitrogen supply: Coordination versus optimization: Opinion

Journal Article Plant and Soil · December 1, 1996 One of the few integrating theories related to allocation is the hypothesis of optimization. While optimization theory has great heuristic appeal and has been used to describe a range of physiological and ecological phenomena, it has major limitations. Opt ... Full text Cite

Effects of CO(2) enrichment on growth and root (15)NH(4) (+) uptake rate of loblolly pine and ponderosa pine seedlings.

Journal Article Tree physiology · November 1996 We examined changes in root growth and (15)NH(4) (+) uptake capacity of loblolly pine (Pinus taeda L.) and ponderosa pine (Pinus ponderosa Douglas. Ex Laws.) seedlings that were grown in pots in a phytotron at CO(2) partial pressures of 35 or 70 Pa with NH ... Full text Cite

Decomposition processes: Modelling approaches and applications

Journal Article Science of the Total Environment · April 12, 1996 Decomposition is a fundamental ecosystem process, strongly influencing ecosystem dynamics through the release of organically bound nutrients. Decomposition is also a complex phenomenon that can be modified by changes in the characteristics of the decaying ... Full text Cite

Descomposition processes: modelling approaches and applications

Journal Article Science of the Total Environment · 1996 Cite

Differential responses of root uptake kinetics of NH+4 and NO-3 to enriched atmospheric CO2 concentration in field-grown loblolly pine

Journal Article Plant, Cell and Environment · 1996 The nitrogen requirement of plants is predominantly supplied by NH+4 and/or NO-3 from the soil solution, but the energetic cost of uptake and assimilation is generally higher for NO-3 than for NH+4. We found that CO2 enrichment of the atmosphere enhanced t ... Cite

Growth and allocation of the arctic sedges Eriohorum angustifolium and E. vaginatum: effects of variable soil oxygen and nutrient availability.

Journal Article Oecologia · November 1995 In arctic tundra soil, oxygen depletion associated with soil flooding may control plant growth either directly through anoxia or indirectly through effects on nutrient availability. This study was designed to evaluate whether plant growth and physiology of ... Full text Cite

EFFECTS OF MAMMALS ON ECOSYSTEM CHANGE AT THE PLEISTOCENE-HOLOCENE BOUNDARY

Conference ARCTIC AND ALPINE BIODIVERSITY: PATTERNS, CAUSES AND ECOSYSTEM CONSEQUENCES · 1995 Cite

Effects of plant size and water relations on gas exchange and growth of the desert shrub Larrea tridentata.

Journal Article Oecologia · March 1994 Larrea tridentata is a xerophytic evergreen shrub, dominant in the arid regions of the southwestern United States. We examined relationships between gasexchange characteristics, plant and soil water relations, and growth responses of large versus small shr ... Full text Cite

Temporal discontinuities in precipitation in the Central North American prairie

Journal Article International Journal of Climatology · 1994 Cite

Relationships between a terrain-based hydrologic model and patch-scale vegetation patterns in an arctic tundra landscape

Journal Article Landscape Ecology · December 1, 1993 Implicit in the relationship between vegetation patterns and landforms is the influence of topography on the water regime at the patch scale. Hence, based on the numerous process-based studies linking plant structure and function to water in the arctic, we ... Full text Cite

Long-Term Response of an Arctic Sedge to Climate Change: A Simulation Study.

Journal Article Ecological applications : a publication of the Ecological Society of America · November 1992 It appears that polar regions of the Earth will bear the brunt of global temperature increases. Because of the ecological importance of the sedge Eriophorum vaginatum in the arctic and the large amount of data available on its growth and physiology, we cho ... Full text Cite

Modelling photosynthesis of cotton grown in elevated CO2

Journal Article Plant, Cell & Environment · January 1, 1992 Cotton plants were grown in CO2‐controlled growth chambers in atmospheres of either 35 or 65 Pa CO2. A widely accepted model of C3 leaf photosynthesis was parameterized for leaves from both CO2 treatments using non‐linear least squares regression technique ... Full text Cite

Modeling the effects of elevated CO2 on plants: extrapolating leaf response to a canopy

Journal Article Agricultural and Forest Meteorology · January 1, 1992 The response of canopies to short-duration exposure to elevated CO2 was examined by using a detailed submodel of single-leaf gas exchange combined with a model of canopy structure and light penetration. The leaf model included a mechanistic gas exchange mo ... Full text Cite

A simple model for predicting soil temperatures in desert ecosystems

Journal Article Soil Science · January 1, 1992 We present a model for predicting soil temperatures in arid regions using current above surface conditions (temperature or temperature and solar radiation) and the annual sinusoidal behavior of temperature in the deeper soil profile. The model is based on ... Full text Cite

A model allocating growth among leaf proteins, shoot structure, and root biomass to produce balanced activity

Journal Article Annals of Botany · January 1, 1991 A model is developed that considers the allocation of carbon and nitrogen substrates to a protein compartment in the shoots, shoot structural components, and root biomass. Inclusion of a shoot-protein compartment allows variation in shoot-specific activity ... Full text Cite

On determining the statistical significance of discontinuities within ordered ecological data

Journal Article Ecology · January 1, 1991 Boundaries between adjacent ecosystem units may be important in determining ecosystem structure and function across heterogeneous landscapes. Such boundaries are potentially important sites for early detection of global climate change effects. Yet traditio ... Full text Cite

A general model of litter decomposition in the northern Chihuahuan Desert

Journal Article Ecological Modelling · January 1, 1991 Numerous empirical studies have described the pathways of mass, C and N flows during decomposition, but there remains a paucity of data on underlying mechanisms in arid ecosystems. In the northern Chihuahuan Desert, termites remove large quantities of litt ... Full text Cite

The influence of carbon dioxide and daily photon-flux density on optimal leaf nitrogen concentration and root: Shoot ratio

Journal Article Annals of Botany · January 1, 1991 Using a cost-benefit model, the leaf nitrogen concentration and root : shoot ratio that maximize whole-plant relative growth rate are determined as a function of the above-ground environment (integrated daily photon flux density and the concentration of ca ... Full text Cite

Environmental effects on CO2 efflux from water track and tussock tundra in arctic Alaska, USA

Journal Article Arctic & Alpine Research · January 1, 1991 Data from the Philip Smith Mountains suggest that both soil temperature and soil moisture limit CO2 efflux in water track and tussock tundra communities and that the relative importance of these factors changes throughout the growing season. -from Authors ... Full text Cite

Factors influencing carbon fixation and water use by mediterranean sclerophyll shrubs during summer drought.

Journal Article Oecologia · March 1990 Mediterranean sclerophyll shrubs respond to seasonal drought by adjusting the amount of leaf area exposed and by reducing gas exchange via stomatal closure mechanisms. The degree to which each of these modifications can influence plant carbon and water bal ... Full text Cite

MODEL STRUCTURE AND DATA-BASE DEVELOPMENT

Conference PROCESS MODELING OF FOREST GROWTH RESPONSES TO ENVIRONMENTAL STRESS · 1990 Cite

The contribution of abiotic processes to buried litter decomposition in the northern Chihuahuan desert.

Journal Article Oecologia · April 1989 Creosobebush (Larrea tridentata) fine litter was treated with either the general biocide HgCl2 and CuSO4 or water (controls) and buried 5 cm beneath the soil surface in the northern Chihuahuan Desert. The treated litter showed signifi ... Full text Cite

A MODULAR STRUCTURE FOR PLANT-GROWTH SIMULATION-MODELS

Conference BIOMASS PRODUCTION BY FAST-GROWING TREES · 1989 Cite

Patterns of stratified soil water loss in a chihuahuan desert community

Journal Article Soil Science · January 1, 1989 An accurate assessment of the moisture content of surface soils in arid and semiarid systems is necessary to predict the productivities of shallow-rooted plants and decomposition rates of surface and near-surface litter. Soil water loss has often been assu ... Full text Cite

The extraction of al, fe and si from a range of new zealand soils by hydroxylamine and ammonium oxalate solutions

Journal Article Australian Journal of Soil Research · January 1, 1989 The elements Al, Fe and Si were extracted with acid oxalate and acid (HCI) hydroxylamine by using 36 samples from eight different soils, and the results for each extractant were compared. Parent materials were largely volcanic in nature, but eight samples ... Full text Cite

Influence of soil moisture regime on the respiration response of soilssubjected to osmotic stress

Journal Article Australian Journal of Soil Research · January 1, 1989 The influence of the soil moisture regime on the tolerance of the soil micro-organisms to increased osmotic stress was examined by laboratory tests with a range of New Zealandsoils. Soils from various climatic regions (moist, intermediate and dry) were ame ... Full text Cite

Influence of pH, exchangeable aluminium and 0.02 M CaCl2-extractable aluminium on the growth and nitrogen-fixing activity of white clover (Trifolium repens) in some New Zealand soils

Journal Article Plant and Soil · September 1, 1988 The effects of soil acidity on the growth and N2-fixing activity of white clover in seven acid topsoils and subsoils of New Zealand were investigated using a glasshouse experiment. The application of phosphate (Ca(H2PO4)2) to the soils resulted in very lar ... Full text Cite

Impact of gypsy moth infestation on forest succession in the North Carolina Piedmont: A simulation study

Journal Article Ecological Modelling · January 1, 1987 A computer simulation model was developed to examine the long term impact of a hypothetical gypsy moth infestation on forest dynamics in the North Carolina Piedmont. The forest growth submodel is based on Johnson's (1977) model of forest succession on the ... Full text Cite

How desertification affects nitrogen limitation of primary production on Chihuahuan Desert watersheds

Journal Article General Technical Report - US Department of Agriculture, Forest Service · January 1, 1987 It is hypothesized that the shift from perennial clump grasses to shrub dominated ecosystems in the Chihuahuan Desert has resulted in a change from predominantly water limited ecosystems to nitrogen-water limited ecosystems. In shrublands N and water are c ... Cite

Plant growth analysis of discontinuous growth data: A modified Richards function

Journal Article Scientia Horticulturae · January 1, 1986 A method is presented for analyzing growth data of plants with discontinuous relative growth rates resulting from a sudden short-term change in the environment of the plants. This technique provides a quantification of a treatment effect on plant growth wh ... Full text Cite

Modeling the response of ecosystems to fossil fuel emissions: Carbon dioxide and pollutant interactions

Journal Article Proceedings Air Pollution Control Association · 1986 Cite

Predicting the response of plants to increasing carbon dioxide: A critique of plant growth models

Journal Article Ecological Modelling · January 1, 1985 It is widely recognized that increasing global carbon dioxide concentration in the atmosphere may alter the growth of plants. This has lead to speculation about the long-term impact of rising CO2 on agricultural productivity and on natural ecosystems, e.g. ... Full text Cite

A model of canopy irradiance in relation to changing leaf area in a phytotron-grown snap bean (Phaseolus vulgaris L.) Crop

Journal Article International Journal of Biometeorology · March 1, 1984 Simple exponential decay models were used to describe the variation in irradiance profiles within a snap bean (Phaseolus vulgaris L.) canopy over a 33-day period of canopy development. The extinction coefficients of these models were varied over time as a ... Full text Cite

Perspectives of air pollution research on plants

Journal Article Reviews in Toxicology · 1984 Cite

A Shoot:Root Partitioning Model

Journal Article Annals of Botany · 1982 Cite

Validation of a primary production model of the desert shrub Larrea tridentata using soil-moisture augmentation experiments.

Journal Article Oecologia · January 1981 In previous papers we have described and verified a primary production model of the desert shrub Larrea tridentata. Here we address the validation phase of the evaluation of this model. Two versions of the model which differ in the priority scheme used for ... Full text Cite

Some misconceptions of mathematical modelling

Journal Article What's New in Plant Physiology · 1979 Cite

Some effects of soil-moisture availability on above-ground production and reproductive allocation in Larrea tridentata (DC) Cov.

Journal Article Oecologia · January 1979 Data from the US/IBP Desert Biome validation studies indicate that above-ground production and biomass allocated to reproduction in Larrea tridentata vary from one year to another depending upon the timing and extent of soil-moisture availability. In an at ... Full text Cite

A net CO2 exchange model for Larrea tridentata

Journal Article Photosynthetica · 1979 Cite

Size-biomass relations of several Chihuahuan Desert shrubs

Journal Article American Midland Naturalist · 1975 Cite