Scholars@Duke
Sari Palmroth

Sari Palmroth

Research Professor in the Division of Environmental Natural Sciences
Environmental Natural Science
sari.palmroth@duke.edu
Box 90328, Durham, NC 27708-0328
A246A Lev Sci Res Ctr, Durham, NC 27708

Selected Publications

Similar response of canopy conductance to increasing vapor pressure deficit and decreasing soil conductivity with drought among five morphologically contrasting but co-occurring pine species

Journal Article Agricultural and Forest Meteorology · May 1, 2025 Knowledge of plant hydraulics facilitates our understanding of the capabilities of forests to withstand droughts. This common-garden study quantified the hydraulic response to variation in sandy soil conductivity and atmospheric vapor pressure deficit (VPD ... Full text Cite

Extramatrical mycelial biomass is mediated by fine root mass and ectomycorrhizal fungal community composition across tree species.

Journal Article The Science of the total environment · November 2024 In many ecosystems, a large fraction of gross primary production is invested in mycorrhiza. Ectomycorrhizal (ECM) mycelium is involved in regulating soil carbon and nutrient cycling. However, little is known about how mycelial biomass, production and turno ... Full text Cite

Overlooked branch turnover creates a widespread bias in forest carbon accounting.

Journal Article Proceedings of the National Academy of Sciences of the United States of America · October 2024 Most measurements and models of forest carbon cycling neglect the carbon flux associated with the turnover of branch biomass, a physiological process quantified for other organs (fine roots, leaves, and stems). Synthesizing data from boreal, temperate, and ... Full text Cite

Increased leaf area index and efficiency drive enhanced production under elevated atmospheric [CO2 ] in a pine-dominated stand showing no progressive nitrogen limitation.

Journal Article Global change biology · February 2024 Enhancement of net primary production (NPP) in forests as atmospheric [CO2 ] increases is likely limited by the availability of other growth resources. The Duke Free Air CO2 Enrichment (FACE) experiment was located on a moderate-ferti ... Full text Cite

The response of coarse root biomass to long-term CO2 enrichment and nitrogen application in a maturing Pinus taeda stand with a large broadleaved component.

Journal Article Global change biology · February 2022 Elevated atmospheric CO2 (eCO2 ) typically increases aboveground growth in both growth chamber and free-air carbon enrichment (FACE) studies. Here we report on the impacts of eCO2 and nitrogen amendment on coarse root bioma ... Full text Cite

Biomass increases attributed to both faster tree growth and altered allometric relationships under long-term carbon dioxide enrichment at a temperate forest.

Journal Article Global change biology · April 2020 Increases in atmospheric carbon dioxide (CO2 ) concentrations are expected to lead to increases in the rate of tree biomass accumulation, at least temporarily. On the one hand, trees may simply grow faster under higher CO2 concentrati ... Full text Cite

Mechanisms for minimizing height-related stomatal conductance declines in tall vines.

Journal Article Plant, cell & environment · November 2019 The ability to transport water through tall stems hydraulically limits stomatal conductance (gs ), thereby constraining photosynthesis and growth. However, some plants are able to minimize this height-related decrease in gs , regardle ... Full text Cite

Nitrogen supply and other controls of carbon uptake of understory vegetation in a boreal Picea abies forest

Journal Article Agricultural and Forest Meteorology · October 15, 2019 In boreal forests, carbon (C) uptake by understory may be too large to be ignored and too variable in space to be assumed a constant fraction of the ecosystem gross primary production. To improve estimates of understory production in these ecosystems, we n ... Full text Cite

Anatomical changes with needle length are correlated with leaf structural and physiological traits across five Pinus species.

Journal Article Plant, cell & environment · May 2019 The genus Pinus has wide geographical range and includes species that are the most economically valued among forest trees worldwide. Pine needle length varies greatly among species, but the effects of needle length on anatomy, function, and coordination an ... Full text Cite

Variation in the performance and thermostability of photosystem II in European beech (Fagus sylvatica L.) provenances is influenced more by acclimation than by adaptation

Journal Article European Journal of Forest Research · February 15, 2019 The assisted migration of resistant seeds and seedlings may be a key to mitigating the effects of climate change on the productivity and composition of forest ecosystems. These efforts require an understanding of the intraspecific variability in the respon ... Full text Cite

Differential responses of Picea asperata and Betula albosinensis to nitrogen supply imposed by water availability.

Journal Article Tree physiology · November 2018 A pot experiment was conducted to investigate the effects of nitrogen (N) addition (0, 20, 40 g N m-2 year-1, N0, N20, N40, respectively) on the growth, and biomass accumulation and allocation of coniferous and deciduous (Picea asperata Mast. and Betula al ... Full text Cite

Evapotranspiration and water yield of a pine-broadleaf forest are not altered by long-term atmospheric [CO2 ] enrichment under native or enhanced soil fertility.

Journal Article Global change biology · October 2018 Changes in evapotranspiration (ET) from terrestrial ecosystems affect their water yield (WY), with considerable ecological and economic consequences. Increases in surface runoff observed over the past century have been attributed to increasing atmospheric ... Full text Cite

Water balance of pine forests: Synthesis of new and published results

Journal Article Agricultural and Forest Meteorology. · September 2018 The forest hydrologic cycle is expected to have important feedback responses to climate change, impacting processes ranging from local water supply and primary productivity to global water and energy cycles. Here, we analyzed water budgets of pine forests ... Full text Cite

Transport in a coordinated soil-root-xylem-phloem leaf system

Journal Article Advances in Water Resources · September 1, 2018 Links between the carbon and water economies of plants are coupled by combining the biochemical demand for atmospheric CO2 with gas transfer through stomates, liquid water transport in the soil-xylem hydraulic system and sucrose export in the ph ... Full text Open Access Cite

Dynamics of soil CO2 efflux under varying atmospheric CO2 concentrations reveal dominance of slow processes.

Journal Article Global change biology · September 2017 We evaluated the effect on soil CO2 efflux (FCO2 ) of sudden changes in photosynthetic rates by altering CO2 concentration in plots subjected to +200 ppmv for 15 years. Five-day intervals of exposure to elevated ... Full text Cite

Informing climate models with rapid chamber measurements of forest carbon uptake.

Journal Article Global change biology · May 2017 Models predicting ecosystem carbon dioxide (CO2 ) exchange under future climate change rely on relatively few real-world tests of their assumptions and outputs. Here, we demonstrate a rapid and cost-effective method to estimate CO2 ex ... Full text Cite

The carbon bonus of organic nitrogen enhances nitrogen use efficiency of plants.

Journal Article Plant, cell & environment · January 2017 The importance of organic nitrogen (N) for plant nutrition and productivity is increasingly being recognized. Here we show that it is not only the availability in the soil that matters, but also the effects on plant growth. The chemical form of N taken up, ... Full text Open Access Cite

On the variability of the ecosystem response to elevated atmospheric CO2 across spatial and temporal scales at the Duke Forest FACE experiment

Journal Article Agricultural and forest meteorology. · January 2017 While the significance of elevated atmospheric CO2 concentration on instantaneous leaf-level processes such as photosynthesis and transpiration is rarely disputed, its integrated effect at ecosystem level and at long-time scales remains a subject of debate ... Full text Cite

Ecophysiological variation of transpiration of pine forests: synthesis of new and published results.

Journal Article Ecological applications : a publication of the Ecological Society of America · January 2017 Canopy transpiration (EC ) is a large fraction of evapotranspiration, integrating physical and biological processes within the energy, water, and carbon cycles of forests. Quantifying EC is of both scientific and practical importance, ... Full text Cite

A test of the hydraulic vulnerability segmentation hypothesis in angiosperm and conifer tree species.

Journal Article Tree physiology · August 2016 Water transport from soils to the atmosphere is critical for plant growth and survival. However, we have a limited understanding about many portions of the whole-tree hydraulic pathway, because the vast majority of published information is on terminal bran ... Full text Cite

Wind-induced leaf transpiration

Journal Article Advances in Water Resources · December 1, 2015 While the significance of leaf transpiration (fe) on carbon and water cycling is rarely disputed, conflicting evidence has been reported on how increasing mean wind speed (U) impacts fe from leaves. Here, conditions promoting enhancem ... Full text Cite

Conversion of natural forests to managed forest plantations decreases tree resistance to prolonged droughts

Journal Article Forest Ecology and Management. · November 2015 Throughout the southern US, past forest management practices have replaced large areas of native forests with loblolly pine plantations and have resulted in changes in forest response to extreme weather conditions. However, uncertainty remains about the re ... Full text Open Access Cite

Stem compression reversibly reduces phloem transport in Pinus sylvestris trees.

Journal Article Tree physiology · October 2015 Manipulating tree belowground carbon (C) transport enables investigation of the ecological and physiological roles of tree roots and their associated mycorrhizal fungi, as well as a range of other soil organisms and processes. Girdling remains the most rel ... Full text Cite

Inter-annual variability of precipitation constrains the production response of boreal Pinus sylvestris to nitrogen fertilization

Journal Article Forest Ecology and Management. · July 2015 Tree growth resources and the efficiency of resource-use for biomass production determine the productivity of forest ecosystems. In nutrient-limited forests, nitrogen (N)-fertilization increases foliage [N], which may increase photosynthetic rates, leaf ar ... Full text Open Access Cite

Increases in atmospheric CO2 have little influence on transpiration of a temperate forest canopy.

Journal Article The New phytologist · January 2015 Models of forest energy, water and carbon cycles assume decreased stomatal conductance with elevated atmospheric CO2 concentration ([CO2]) based on leaf-scale measurements, a response not directly translatable to canopies. Where canopy-atmosphere are well- ... Full text Cite

How eco-evolutionary principles can guide tree breeding and tree biotechnology for enhanced productivity.

Journal Article Tree physiology · November 2014 Tree breeding and biotechnology can enhance forest productivity and help alleviate the rising pressure on forests from climate change and human exploitation. While many physiological processes and genes are targeted in search of genetically improved tree p ... Full text Cite

Nitrogen-addition effects on leaf traits and photosynthetic carbon gain of boreal forest understory shrubs.

Journal Article Oecologia · June 2014 Boreal coniferous forests are characterized by fairly open canopies where understory vegetation is an important component of ecosystem C and N cycling. We used an ecophysiological approach to study the effects of N additions on uptake and partitioning of C ... Full text Cite

Sustained effects of atmospheric [CO2] and nitrogen availability on forest soil CO2 efflux.

Journal Article Glob Chang Biol · April 2014 Soil CO2 efflux (Fsoil ) is the largest source of carbon from forests and reflects primary productivity as well as how carbon is allocated within forest ecosystems. Through early stages of stand development, both elevated [CO2] and availability of soil nit ... Full text Link to item Cite

Short-term response of soil respiration to nitrogen fertilization in a subtropical evergreen forest

Journal Article Soil Biology and Biochemistry · January 1, 2014 Little is known about the effects of nitrogen (N) additions on soil respiration (Rs) in tropical and subtropical forests. We therefore conducted an N-fertilization experiment in a subtropical evergreen forest in eastern China to better understand the short ... Full text Cite

Optimal plant water-use strategies under stochastic rainfall

Journal Article Water Resources Research · January 1, 2014 Plant hydraulic traits have been conjectured to be coordinated, thereby providing plants with a balanced hydraulic system that protects them from cavitation while allowing an efficient transport of water necessary for photosynthesis. In particular, observa ... Full text Cite

Optimization of stomatal conductance for maximum carbon gain under dynamic soil moisture

Journal Article Advances in Water Resources · December 1, 2013 Optimization theories explain a variety of forms and functions in plants. At the leaf scale, it is often hypothesized that carbon gain is maximized, thus providing a quantifiable objective for a mathematical definition of optimality conditions. Eco-physiol ... Full text Cite

Organic nitrogen uptake of Scots pine seedlings is independent of current carbohydrate supply.

Journal Article Tree physiology · June 2013 In boreal forests, seedling establishment is limited by various factors including soil nitrogen (N) availability. Seedlings may absorb N from soil in a variety of inorganic and organic forms; however, the energy and thus carbohydrate requirements for uptak ... Full text Cite

Hydraulic limits on maximum plant transpiration and the emergence of the safety-efficiency trade-off.

Journal Article New Phytol · April 2013 Soil and plant hydraulics constrain ecosystem productivity by setting physical limits to water transport and hence carbon uptake by leaves. While more negative xylem water potentials provide a larger driving force for water transport, they also cause cavit ... Full text Link to item Cite

Spatial and temporal variability of soil CO2 efflux in three proximate temperate forest ecosystems

Journal Article Agricultural and Forest Meteorology. · April 2013 The magnitude of CO2 flux from soil (Fsoil) varies with primary productivity and environmental drivers of respiration, soil temperature (Tsoil) and moisture, all of which vary temporally and spatially. To quantify the sources of Fsoil variability, we first ... Full text Cite

On the complementary relationship between marginal nitrogen and water-use efficiencies among Pinus taeda leaves grown under ambient and CO2-enriched environments.

Journal Article Annals of botany · March 2013 Background and aimsWater and nitrogen (N) are two limiting resources for biomass production of terrestrial vegetation. Water losses in transpiration (E) can be decreased by reducing leaf stomatal conductance (g(s)) at the expense of lowering CO(2) ... Full text Cite

Causality and persistence in ecological systems: a nonparametric spectral granger causality approach.

Journal Article The American naturalist · April 2012 Abstract Directionality in coupling, defined as the linkage relating causes to their effects at a later time, can be used to explain the core dynamics of ecological systems by untangling direct and feedback relationships between the different components o ... Full text Cite

Elevated CO 2 affects photosynthetic responses in canopy pine and subcanopy deciduous trees over 10 years: A synthesis from Duke FACE

Journal Article Global Change Biology · January 1, 2012 Leaf responses to elevated atmospheric CO 2 concentration (C a) are central to models of forest CO 2 exchange with the atmosphere and constrain the magnitude of the future carbon sink. Estimating the magnitude of primary pr ... Full text Cite

Effects of stomatal delays on the economics of leaf gas exchange under intermittent light regimes.

Journal Article The New phytologist · November 2011 • Understory plants are subjected to highly intermittent light availability and their leaf gas exchanges are mediated by delayed responses of stomata and leaf biochemistry to light fluctuations. In this article, the patterns in stomatal delays across biome ... Full text Cite

Modelling understorey light for seedling regeneration in continuous cover forestry canopies

Journal Article FORESTRY · October 2011 Continuous cover forestry (CCF) aims at enhancing stand structural diversity and favouring natural regeneration. To give guidance on how to manage a CCF stand to achieve seedling growth below canopy, an estimate of light transmittance is required. So far, ... Full text Cite

Optimizing stomatal conductance for maximum carbon gain under water stress: a meta-analysis across plant functional types and climates

Journal Article Functional ecology. · June 2011 1. Quantification of stomatal responses to environmental variables, in particular to soil water status, is needed to model carbon and water exchange rates between plants and the atmosphere. 2. Models based on stomatal optimality theory successfully describ ... Full text Cite

Increases in the flux of carbon belowground stimulate nitrogen uptake and sustain the long-term enhancement of forest productivity under elevated CO₂.

Journal Article Ecology letters · April 2011 The earth's future climate state is highly dependent upon changes in terrestrial C storage in response to rising concentrations of atmospheric CO₂. Here we show that consistently enhanced rates of net primary production (NPP) are sustained by a C-cascade t ... Full text Cite

Analysis of the sensitivity of absorbed light and incident light profile to various canopy architecture and stand conditions

Journal Article TREE PHYSIOLOGY · January 2011 We analyzed the effect of simplifying assumptions in canopy representation of radiation transfer models, comparing modeled diffuse non-interceptance and photosynthetic photon flux density with measurements at different layers of complex pine-broadleaved ca ... Full text Cite

Economics of leaf gas exchange under water stress

Journal Article Functional Ecology · 2011 Cite

Estimation of long-term basin scale evapotranspiration from streamflow time series

Journal Article Water Resources Research · October 29, 2010 We estimated long-term annual evapotranspiration (ETQ) at the watershed scale by combining continuous daily streamflow (Q) records, a simplified watershed water balance, and a nonlinear reservoir model. Our analysis used Q measured from 11 water ... Full text Open Access Cite

Interannual Invariability of Forest Evapotranspiration and Its Consequence to Water Flow Downstream

Journal Article Ecosystems. · April 2010 Although drought in temperate deciduous forests decreases transpiration rates of many species, stand-level transpiration and total evapotranspiration is often reported to exhibit only minor interannual variability with precipitation. This apparent contradi ... Full text Cite

A stomatal optimization theory to describe the effects of atmospheric CO2 on leaf photosynthesis and transpiration.

Journal Article Annals of botany · March 2010 Background and aimsGlobal climate models predict decreases in leaf stomatal conductance and transpiration due to increases in atmospheric CO2. The consequences of these reductions are increases in soil moisture availability and continental scale r ... Full text Cite

Physiological responses of Norway spruce (Picea abies) seedlings to drought stress.

Journal Article Tree physiology · February 2010 Four-year-old seedlings of Picea abies [L.] Karst (Norway spruce) were grown in semi-controlled conditions with three watering regimes. The seedlings in the control group (c) were watered to prevent any dehydration effect. The two remaining groups were sub ... Full text Cite

Acclimation of leaf hydraulic conductance and stomatal conductance of Pinus taeda (loblolly pine) to long-term growth in elevated CO(2) (free-air CO(2) enrichment) and N-fertilization.

Journal Article Plant, cell & environment · November 2009 We investigated how leaf hydraulic conductance (K(leaf)) of loblolly pine trees is influenced by soil nitrogen amendment (N) in stands subjected to ambient or elevated CO(2) concentrations (CO(2)(a) and CO(2)(e), respectively). We also examined how K(leaf) ... Full text Cite

Leaf stomatal responses to vapour pressure deficit under current and CO(2)-enriched atmosphere explained by the economics of gas exchange.

Journal Article Plant, cell & environment · August 2009 Using the economics of gas exchange, early studies derived an expression of stomatal conductance (g) assuming that water cost per unit carbon is constant as the daily loss of water in transpiration (f(e)) is minimized for a given gain in photosynthesis (f( ... Full text Cite

The effects of elevated atmospheric CO₂ and nitrogen amendments on subsurface CO₂ production and concentration dynamics in a maturing pine forest

Journal Article Biogeochemistry. · July 2009 Profiles of subsurface soil CO₂ concentration, soil temperature, and soil moisture, and throughfall were measured continuously during the years 2005 and 2006 in 16 locations at the free air CO₂ enrichment facility situated within a temperate loblolly pine ... Full text Cite

Short-term effects of fertilization on photosynthesis and leaf morphology of field-grown loblolly pine following long-term exposure to elevated CO(2) concentration.

Journal Article Tree physiology · April 2008 We examined effects of a first nitrogen (N) fertilizer application on upper-canopy needle morphology and gas exchange in approximately 20-m-tall loblolly pine (Pinus taeda L.) exposed to elevated carbon dioxide concentration ([CO(2)]) for 9 years. Duke For ... Full text Cite

Estimation of light interception properties of conifer shoots by an improved photographic method and a 3D model of shoot structure.

Journal Article Tree physiology · October 2007 The spherical mean of the shoot silhouette-to-total leaf area ratio (STAR) and the shoot transmission coefficient (c) are two key structural parameters in radiative transfer models for calculating canopy photosynthesis and leaf area index. The standard opt ... Full text Cite

Aboveground sink strength in forests controls the allocation of carbon below ground and its [CO2]-induced enhancement.

Journal Article Proceedings of the National Academy of Sciences of the United States of America · December 2006 The partitioning among carbon (C) pools of the extra C captured under elevated atmospheric CO2 concentration ([CO2]) determines the enhancement in C sequestration, yet no clear partitioning rules exist. Here, we used first principles and published data fro ... Full text Cite

Effects of tree size and position on pipe model ratios in Scots pine

Journal Article Canadian Journal of Forest Research · June 1, 2005 We investigate how the foliage mass to wood area ratios depend on tree and stand characteristics of previously collected data from Scots pine (Pinus sylvestris L.). Our analysis allowed a separation of the relationship between stem and branch cross-section ... Full text Cite

Fertilization has little effect on light-interception efficiency of Picea abies shoots.

Journal Article Tree physiology · November 2002 We investigated effects of nutrient availability on shoot structure and light-interception efficiency based on data from control (C) and irrigated + fertilized (IL) trees of Norway spruce (Picea abies (L.) Karst.). The sampling of 1-year-old shoots was des ... Full text Cite

Shoot structure and photosynthetic efficiency along the light gradient in a Scots pine canopy.

Journal Article Tree physiology · August 2001 We examined the effects of structural and physiological acclimation on the photosynthetic efficiency of Scots pine (Pinus sylvestris L.) shoots. We estimated daily light interception (DLI) and photosynthesis (DPHOT) of a number of sample shoots situated at ... Full text Cite

Tree scale distributed multipoint measuring system of photosynthetically active radiation

Journal Article Agricultural and Forest Meteorology · January 6, 2001 A tree scale distributed multipoint measuring system of photosynthetically active radiation (PAR) has been designed. The system is divided into a central unit, measuring units and sensor-amplifiers. Measurements can be carried out with a maximum number of ... Full text Cite

Evaluation of the importance of acclimation of needle structure, photosynthesis, and respiration to available photosynthetically active radiation in a Scots pine canopy

Journal Article Canadian Journal of Forest Research · January 1, 2001 We analyzed the combined effect of differences in the photosynthetic light response curve and in the distributions of photosynthetically active radiation (PAR) irradiance within the canopy on the CO2 exchange rates of Scots pine (Pinus sylvestri ... Full text Cite

Effect of variations of PAR on CO2 exchange estimation for Scots pine

Journal Article Agricultural and Forest Meteorology · February 25, 2000 A set-up with 161 photosynthetically active radiation (PAR) sensors was used to investigate spatio-temporal variations of irradiance for five horizontal arrays within a Scots pine canopy. The measured PAR was converted to CO2 exchange using of a ... Full text Cite

Structural adaptation rather than water conservation was observed in Scots pine over a range of wet to dry climates.

Journal Article Oecologia · November 1999 We investigated the functional and structural responses of Scots pine to climate and estimated the importance of the genotype on the traits studied. We analysed 13C isotope discrimination (Δ13C) of various provenances in a common gard ... Full text Cite

Fine scale measurement and simulation of penumbral radiation formed by a pine shoot

Journal Article Agricultural and Forest Meteorology · May 31, 1999 A new instrument for measuring photosynthetically active radiation (PAR) was used to investigate changes in the distribution of direct sunlight on a plane shaded by a Scots pine shoot situated at different distances, and to test a previously developed mode ... Full text Cite

Utilizing a multipoint measuring system of photosynthetically active radiation in photosynthetic studies within canopies

Journal Article Silva Fennica · January 1, 1998 A novel multipoint measuring system of photosynthetically active radiation (PAR) has been constructed and operated within a Scots pine canopy. A regular grid of 800 measuring points has been incorporated into a cuvette to observe the spatial and temporal d ... Full text Cite

Variations and vertical profiles of trace gas and aerosol concentrations and CO2 exchange in eastern Lapland

Journal Article Atmospheric Environment · October 1, 1997 This article presents results of measurements performed at Varrio environmental research station in Finland during 1992 to 1995. The aim of the station is to obtain more information on air quality as influenced by the Kola industrial areas and the effects ... Full text Cite

Observations of ultrafine aerosol particle formation and growth in boreal forest

Journal Article Geophysical Research Letters · January 1, 1997 Number size distribution of ambient submicron and ultrafine aerosol particles have been measured on a continuous basis (every 10 minutes) for three quarters of the year 1996, at a forest site in Southern Finland. Continuous monitoring offers additional ins ... Full text Cite