LB 5-41 - Integrating data and theory to understand leaf-level nitrogen responses to soil nitrogen

Thursday, August 10, 2023

5:00 PM – 6:30 PM PDT

Location: ESA Exhibit Hall

Presenting Author(s)

AC

Alissar Cheaib

Postdoctoral research associate
Texas Tech University
Lubbock, Texas, United States

Coauthor(s)

NS

Nicholas G. G. Smith

Assistant Professor
Texas Tech University
Lubbock, Texas, United States
EW

Elizabeth F. Waring

Department of Natural Sciences, Northeastern State University, Tahlequah, OK, USA, United States
RM

Risa McNellis

Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA, United States
EP

Evan A A. Perkowski

PhD candidate
Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA
Lubbock, Texas, United States
JM

Jason P Martina, n/a

Assistant Professor
Department of Biology, Texas State University, San Marcos, TX, 78666, USA, Texas, United States
ES

Eric W W. Seabloom

Department of Ecology, Evolution, and Behavior, University of Minnesota, Saint Paul, MN, United States
PW

Peter A A. Wilfahrt

Department of Ecology, Evolution, and Behavior, University of Minnesota, Saint Paul, MN, United States
ND

Ning Dong

Department of Biological Sciences, Macquarie University, North Ryde, NSW 2109, Australia, Australia
IP

Iain Colin C. Prentice

Department of Biological Sciences, Macquarie University, North Ryde, NSW 2109, Australia, Australia
IW

Ian Wright

Department of Biological Sciences, Macquarie University, North Ryde, NSW 2109, Australia, Australia
SP

Sally A A. Power

Hawkesbury Institute for the Environment, Western Sydney University, Sydney, Australia
Sydney, New South Wales, Australia
EH

Erika I. I. Hersch-Green, PhD

Associate Professor
Department of Biological Sciences, Michigan Technological University, Houghton, MI, USA
Houghton, Michigan, United States
AR

Anita C Ritsch

Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Community Ecology, Birmensdorf, Switzerland, Switzerland
MC

Maria C Caldeira

Forest Research Centre, School of Agriculture, University of Lisbon, Portugal, Portugal
CN

Carla Nogueira

Forest Research Centre, School of Agriculture, University of Lisbon, Portugal, Portugal
QC

Qingqing Chen

Institute of Ecology, College of Urban and Environmental Science, Peking University, Beijing, China
Beijing, NY, China (People's Republic)

Accurate representation of the relationship between soil nitrogen availability and photosynthesis is crucial to reliably predict the coupling between carbon and nitrogen cycles in Earth System Models (ESMs) and, thus, climate feedbacks. Most representations of this relationship assume a positive correlation between soil nitrogen availability, leaf nitrogen content, and photosynthetic capacity. However, the effect of climatic drivers (light, temperature, and aridity) on the relationship between nitrogen demand for photosynthesis in leaves and nitrogen availability in soils can be strong and an understanding of these effects is necessary to enable quantitative predictions of key photosynthetic traits in models. Theory predicts an increase in leaf nitrogen demand for photosynthesis with decreasing temperature (to compensate for the reduction of photosynthetic enzyme activities) and with aridity (to compensate for the reduction of internal CO2). Hence, assessing experimentally these predictions and analyzing the interactions between climatic factors, soil nitrogen availability, leaf traits, and plant growth is necessary to improve ESMs. Here, we compared theory to data from a globally-distributed network of nutrient addition experiments in grasslands (Nutrient Network). Covariate data included leaf nitrogen content (Nmass), leaf mass per area (LMA), and the ratio of leaf intracellular to ambient CO2 (χ), which reflects stomatal responses to temperature, atmospheric pressure, and aridity. Across the network, the increase in Nmass with increasing soil nitrogen availability was higher in cold environments when compared to hotter environments but was weakly affected by aridity. These results suggest that shifts in Nmass are likely the function of both soil nitrogen supply and plant nitrogen demand to build biomass. These findings are encouraging to explore a larger global dataset covering stronger contrasting climatic gradients to more fully understand the mechanisms underlying these dynamics for the development of the next generation of Earth System Models.