Atmospheric nitrogen (N) deposition continues to be a major component of global change to impact plant functioning, but a mechanistic understanding of plant photosynthetic response is needed to predict changes in terrestrial carbon (C) gain under conditions of chronically elevated atmospheric N deposition.
In a recent article published in Global Change Biology entitled "Global response patterns of plant photosynthesis to nitrogen addition: A meta-analysis", a research group led by Prof. YE Qing at South China Botanical Garden (SCBG) of the Chinese Academy of Sciences (CAS), has made advances in understanding the mechanisms of plant photosynthesis in response to N deposition.
The researchers developed a conceptual model depicting the mechanisms that explain effects of N addition on gross plant photosynthetic C gain (Figure), and using a meta-analysis, they revealed the effects of experimental N addition on 14 photosynthesis-related functional traits.
They found that across 320 terrestrial plant species worldwide, N addition significantly enhanced total leaf area and, as well as leaf photosynthetic capacity, stomatal conductance and transpiration rate, while N addition had little effect on plant water use efficiency.
In addition, the effects of N addition on plant photosynthesis were dependent upon plant functional types, experimental and environmental factors. As experimental duration and N load increased, the responses of leaf photosynthetic capacity diminished, while plant transpiration increased significantly.
It was concluded that N deposition will enhance gross photosynthetic C gain of terrestrial plants at the cost of water loss to the atmosphere.
"However, the effects of N addition on C gain might diminished over time, while plant water use might be amplified if N deposition persists." said Dr. LIANG Xingyun, the first author of this study.
Fig. Conceptual model depicting the mechanisms that explain the effects of N addition on gross plant photosynthetic C gain (Image by SCBG)
Source: Chinese Academy of Sciences