Chin J Plant Ecol ›› 2014, Vol. 38 ›› Issue (6): 640-652.DOI: 10.3724/SP.J.1258.2014.00060

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Variations in the relationship between maximum leaf carboxylation rate and leaf nitrogen concentration

YAN Shuang1,2,ZHANG Li2,*(),JING Yuan-Shu1,HE Hong-Lin2,YU Gui-Rui2   

  1. 1College of Applied Meteorology, Nanjing University of Information Science and Technology, Nanjing 210044, China
    2Synthesis Research Center of Chinese Ecosystem Research Network, Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
  • Received:2013-12-19 Accepted:2014-03-27 Online:2014-12-19 Published:2014-06-10
  • Contact: ZHANG Li

Abstract:

Aims Maximum leaf carboxylation rate is one of the key parameters determining the photosynthetic capacity of plants. It is affected by irradiance, temperature, moisture, atmospheric CO2 concentration, leaf nitrogen content, and some other factors. Accurate simulation of the responses of the maximum leaf carboxylation rate to varying environmental conditions is the premise for predicting the changes in vegetation productivity and carbon cycle in future environments. Most of the process-based terrestrial carbon cycle models use the Farqhuar photosynthesis model to simulate plant photosynthesis. However, the methods in simulating the relationship between maximum leaf carboxylation rate and leaf nitrogen content differ from each other.
Methods We collected data on maximum leaf carboxylation rate and leaf nitrogen content from literature published during 1990-2013, and analyzed the variations in the relationship between maximum leaf carboxylation rate at 25 ℃ (Vcmax,25) and area-based leaf nitrogen concentration (Na) across different plant functional types and seasons, and in responses to rising atmospheric CO2 and nitrogen supply. Moreover, we reviewed possible causes of those variations and the influencing factors.
Important findings The results showed that: 1) the relationship between Vcmax,25 and Na varied with plant functional types, and the average values of the slope ranged from 16.29 to 50.25 μmol CO2·g N-1·s-1. Deciduous trees generally showed a steeper slope and greater photosynthetic nitrogen use efficiency than evergreen trees due to the differences in leaf mass per area (LMA) and nitrogen allocation to Rubisco. 2) The relationship between Vcmax,25 and Na had seasonal and annual variations. In years without water stress, the highest value of the slope mostly occurred in spring or summer. A change of the slope was related to seasonal variations in LMA and nitrogen allocation to Rubisco. The slope increased in drought seasons or years. 3) The slope of the linear relationship between Vcmax,25 and Na for perennial needle leaf was reduced due to a decrease in Rubisco content in response to elevated CO2. The maximum leaf carboxylation rate, nitrogen content, and the slope of their linear relationship increased with increment of nitrogen application rate. On the basis of these analyses, we suggest that simulating the relationship between maximum leaf carboxylation and leaf nitrogen should consider seasonal variations in LMA and nitrogen allocation to Rubisco, the influences of water stress, atmospheric CO2 concentration, and nitrogen supply level. More multi-factor experimental studies are needed to further investigate the underlying mechanisms of the variations in the relationship between maximum leaf carboxylation rate and leaf nitrogen content, to obtain more observational data with systematic approaches, and thus to further improve ecosystem process-based models.

Key words: leaf nitrogen, maximum leaf carboxylation rate, photosynthesis, terrestrial carbon cycle model