Research Topics
| Ram OrenSummaryAffiliation: Duke University Medical Center Country: USA Publications
| Collaborators
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Detail Information
Publications
Soil fertility limits carbon sequestration by forest ecosystems in a CO2-enriched atmosphereR Oren
Nicholas School of the Environment and Earth Sciences, Duke University, Durham, North Carolina 27708, USA
Nature 411:469-72. 2001..Assessment of future carbon sequestration should consider the limitations imposed by soil fertility, as well as interactions with nitrogen deposition...- Olevi Kull's lifetime contribution to ecologyRam Oren
Nicholas School of the Environment and Earth Sciences, Duke University, Durham, NC 27708 0328, USA
Tree Physiol 28:483-90. 2008..We also review some of his findings on the interactive effects of carbon dioxide and ozone on canopy photosynthesis... 
Re-assessment of plant carbon dynamics at the Duke free-air CO(2) enrichment site: interactions of atmospheric [CO(2)] with nitrogen and water availability over stand developmentHeather R McCarthy
Nicholas School of the Environment and Earth Sciences, Duke University, Durham, NC 27708, USA
New Phytol 185:514-28. 2010....- Are ecosystem carbon inputs and outputs coupled at short time scales? A case study from adjacent pine and hardwood forests using impulse-response analysisPaul C Stoy
Nicholas School of the Environment and Earth Sciences, Duke University, Durham, NC, USA
Plant Cell Environ 30:700-10. 2007..Future efforts to model ecosystem C inputs and outputs in a pulse-response framework must combine measurements of transport in the physical and biological components of terrestrial ecosystems... 
Canopy leaf area constrains [CO2]-induced enhancement of productivity and partitioning among aboveground carbon poolsHeather R McCarthy
Nicholas School of the Environment and Earth Sciences, Duke University, Durham, NC 27708, USA
Proc Natl Acad Sci U S A 103:19356-61. 2006..Further study is necessary to elucidate the mechanisms that control the differential allocation of C among aboveground pools in different forest types...- Analysis of the sensitivity of absorbed light and incident light profile to various canopy architecture and stand conditionsHyun Seok Kim
Nicholas School of Environmental and Earth Sciences, Duke University, Durham, NC 27708 0328, USA
Tree Physiol 31:30-47. 2011..g., broadleaved). However, even in forests with highly clumped shoots (i.e., coniferous), an accurate estimation of absorbed light distribution in stands requires incorporation of stand density in the model... - 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-fertilizationJean Christophe Domec
Nicholas School of the Environment and Earth Sciences, Duke University, Durham, NC 27708, USA
Plant Cell Environ 32:1500-12. 2009.... - Aboveground sink strength in forests controls the allocation of carbon below ground and its [CO2]-induced enhancementSari Palmroth
Nicholas School of the Environment and Earth Sciences, Duke University, Durham, NC 27708, USA
Proc Natl Acad Sci U S A 103:19362-7. 2006.... - Differential responses to changes in growth temperature between trees from different functional groups and biomes: a review and synthesis of dataDanielle A Way
Department of Biology, Duke University, Durham, NC, USA
Tree Physiol 30:669-88. 2010..We discuss the implications of these results in the context of a changing climate and highlight the areas of greatest uncertainty regarding temperature and tree growth where future research is needed... - Actual and potential transpiration and carbon assimilation in an irrigated poplar plantationHyun Seok Kim
Nicholas School of Environmental and Earth Sciences, Duke University, Durham, NC 27708 0328, USA
Tree Physiol 28:559-77. 2008..57 to 1.15 g stem wood C kg(-1) water. Given the economic and social values of water, plantation managers appear to have optimized water use... - A stomatal optimization theory to describe the effects of atmospheric CO2 on leaf photosynthesis and transpirationGabriel Katul
Nicholas School of the Environment, Box 90328, Duke University, Durham, NC 27708, USA
Ann Bot 105:431-42. 2010.... - Variable conductivity and embolism in roots and branches of four contrasting tree species and their impacts on whole-plant hydraulic performance under future atmospheric CO₂ concentrationJean Christophe Domec
Nicholas School of the Environment and Earth Sciences, Duke University, Durham, NC 27708, USA
Tree Physiol 30:1001-15. 2010..The results contributed to our knowledge of the physiological and anatomical mechanisms underpinning the responses of tree species to drought and more generally to global change... - Modeling seed dispersal distances: implications for transgenic Pinus taedaClaire G Williams
Duke University, Department of Biology, Durham, North Carolina 27708, USA
Ecol Appl 16:117-24. 2006..The probability of LDD occurrence of transgenic conifer seeds at distances exceeding 1 km approached 100%... - Leaf stomatal responses to vapour pressure deficit under current and CO(2)-enriched atmosphere explained by the economics of gas exchangeGabriel G Katul
Nicholas School of the Environment, Duke University, Durham, North Carolina, USA
Plant Cell Environ 32:968-79. 2009..We extended the theory to diagnosing experimental results on the sensitivity of g to D under varying c(a)... - Fertilization effects on mean stomatal conductance are mediated through changes in the hydraulic attributes of mature Norway spruce treesEric J Ward
Nicholas School of the Environment and Earth Sciences, Duke University, Durham, NC 27708, USA
Tree Physiol 28:579-96. 2008..e., an increase in g(s)) after pruning scales inversely with K(l)DeltaPsi, indicating that the higher the potential hydraulic support after pruning, the less complete the stomatal compensation for the increase in A(s):A(l)... - Variability in net ecosystem exchange from hourly to inter-annual time scales at adjacent pine and hardwood forests: a wavelet analysisPaul C Stoy
Nicholas School of the Environment and Earth Sciences, Box 90328, Duke University, Durham, NC 27708 0328, USA
Tree Physiol 25:887-902. 2005..The OWT revealed similarities and differences in the scale-wise control of NEE by vegetation with implications for model simplification and improvement... - Estimation of light interception properties of conifer shoots by an improved photographic method and a 3D model of shoot structureMathieu Therezien
Nicholas School of Environmental and Earth Sciences, Duke University, Durham, NC 27708 0328, USA
Tree Physiol 27:1375-87. 2007..16 for a wide range of shoot structures. For applications requiring angle-dependent parameterization, our new model facilitates rapid generation of these radiative transfer parameters... - Canopy nitrogen, carbon assimilation, and albedo in temperate and boreal forests: Functional relations and potential climate feedbacksS V Ollinger
Complex Systems Research Center, Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, NH 03824, USA
Proc Natl Acad Sci U S A 105:19336-41. 2008.... - Carbon dioxide and water vapor exchange in a warm temperate grasslandK A Novick
Department of Civil and Environmental Engineering, Duke University, Box 90329, Durham, North Carolina 27708, USA
Oecologia 138:259-74. 2004..These results, and the results of other studies, suggest that perturbations to the hydrologic cycle are key determinants of C cycling in grassland ecosystems... - Mean canopy stomatal conductance responses to water and nutrient availabilities in Picea abies and Pinus taedaB E Ewers
Nicholas School of the Environment, Duke University, Durham, NC 27708, USA
Tree Physiol 21:841-50. 2001..Despite the large difference in GS both between Picea abies and Pinus taeda and among treatments, stem growth was related to absorbed radiation, and stem growth response to treatment reflected mostly the changes in L... - Mechanisms of long-distance dispersal of seeds by windRan Nathan
Department of Life Sciences, Ben Gurion University of the Negev, Beer Sheva 84105, Israel
Nature 418:409-13. 2002..Because uplifting probabilities are appreciable (as much as 1 5%), and tree seed crops are commonly massive, some LDD events will establish individuals that can critically affect plant dynamics on large scales... - Irreconcilable differences: fine-root life spans and soil carbon persistenceAllan E Strand
Department of Biology, College of Charleston, Charleston, SC 29424, USA
Science 319:456-8. 2008..On the other hand, isotopic techniques systematically underestimate the turnover of individual roots. These differences, by virtue of the separate processes or pools measured, are irreconcilable... - Increases in nitrogen uptake rather than nitrogen-use efficiency support higher rates of temperate forest productivity under elevated CO2Adrien C Finzi
Department of Biology, Boston University, Boston, MA 02215, USA
Proc Natl Acad Sci U S A 104:14014-9. 2007..Biogeochemical models must be reformulated to allow C transfers below ground that result in additional N uptake under elevated CO(2)... - The likely impact of elevated [CO2], nitrogen deposition, increased temperature and management on carbon sequestration in temperate and boreal forest ecosystems: a literature reviewRiitta Hyvönen
Department of Ecology and Environmental Research, Swedish University of Agricultural Sciences SLU, PO Box 7072, SE 750 07 Uppsala, Sweden
New Phytol 173:463-80. 2007..However, management has considerable potential for controlling the C store... - Progressive nitrogen limitation of ecosystem processes under elevated CO2 in a warm-temperate forestAdrien C Finzi
Department of Biology, Boston University, Massachusetts 02215, USA
Ecology 87:15-25. 2006..widening C-to-N ratios and ecosystem-N accrual as processes that drive and delay PNL, respectively. Only direct observations through time will definitively answer this question... - Forest response to elevated CO2 is conserved across a broad range of productivityRichard J Norby
Environmental Sciences Division, Oak Ridge National Laboratory, TN 37831-6422, USA
Proc Natl Acad Sci U S A 102:18052-6. 2005.... - Temporal variability in (13)C of respired CO(2) in a pine and a hardwood forest subject to similar climatic conditionsBehzad Mortazavi
Department of Oceanography, Florida State University, Tallahassee, FL 32306 4320, USA
Oecologia 142:57-69. 2005.... - Time series diagnosis of tree hydraulic characteristicsNathan G Phillips
Boston University, Geography Department, 675 Commonwealth Avenue, Boston, MA 02215, USA
Tree Physiol 24:879-90. 2004.... - Stomatal sensitivity to vapor pressure deficit and its relationship to hydraulic conductance in Pinus palustrisRobert N Addington
Department of Plant Biology, University of Georgia, Athens, GA 30602, USA
Tree Physiol 24:561-9. 2004..Our results are consistent with the hypothesis that stomatal response to D occurs to regulate minimum leaf water potential, and that the sensitivity of this response is related to changes in whole-plant hydraulics...