J Plant Ecol ›› 2017, Vol. 10 ›› Issue (3): 486-496 .DOI: 10.1093/jpe/rtw053

• Research Articles • Previous Articles     Next Articles

Responses and sensitivity of N, P and mobile carbohydrates of dominant species to increased water, N and P availability in semi-arid grasslands in northern China

Xue Wang1,2, Zhuwen Xu1, Caifeng Yan1, Wentao Luo1,2, Ruzhen Wang1,2, Xingguo Han1, Yong Jiang1,* and Mai-He Li1,3   

  1. 1 Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, No. 72 Wenhua Road, Shenhe District, Shenyang 110016, China; 2 College of Resources and Environment, University of Chinese Academy of Sciences, No. 19A Yuquan Road, Shijingshan District, Beijing 100049, China; 3 Forest dynamics, Swiss Federal Research Institute WSl, Zuercherstrasse 111, CH-8903 Birmensdorf, Switzerland
  • Received:2015-07-09 Accepted:2016-05-24 Published:2017-05-23
  • Contact: Li, Mai-He

Responses and sensitivity of N, P and mobile carbohydrates of dominant species to increased water, N and P availability in semi-arid grasslands in northern China

Abstract: Aims We aimed to improve the understanding of the carbon and nutrient physiological responses and adaptation of semi-arid grassland plants to environmental changes.
Methods We investigated plant leaf non-structural carbohydrate (NSC = soluble sugars + starch), nitrogen (N) and phosphorus (P) levels in an Inner Mongolian semi-arid grassland community treated with water, N and P additions for 8 years. Two dominant grasses (Agropyron cristatum (L.) Gaertn., Stipa krylovii Roshev.) and two forbs (Artemisia frigida Willd., Potentilla bifurca L.) were analyzed.
Important findings Water addition decreased plant leaf N and P concentrations, whereas N and P addition increased them, indicating that the semi-arid grassland studied suffers from a shortage of N and P supply. Both N and P addition decreased the levels of soluble sugars, starch and thus also NSC in plant leaves, which may be attributed to (i) increased carbohydrate consumption associated with a higher growth rate, and (ii) a dilution effect of greater plant size under N and P addition. Water addition tended to increase the leaf NSC levels both in the grasses (+9.2%) and forbs (+0.6% only), which may be a result of increased photosynthesis of plants with increased water availability. Under conditions of ambient and increased water supply in the present study, N addition resulted in an N/P ratio of>16 in the grasses but a significantly lower N/P ratio of <11 in the forb species. This finding implies that growth of the two grass species will be limited mainly by P availability but the forbs will still be mainly limited by N supply if N deposition, alone or in combination with summer precipitation, continues to increase as predicted in Inner Mongolia.

Key words: climate change, non-structural carbohydrates, perennial grasses, perennial forbs, steppe

摘要:
Aims We aimed to improve the understanding of the carbon and nutrient physiological responses and adaptation of semi-arid grassland plants to environmental changes.
Methods We investigated plant leaf non-structural carbohydrate (NSC = soluble sugars + starch), nitrogen (N) and phosphorus (P) levels in an Inner Mongolian semi-arid grassland community treated with water, N and P additions for 8 years. Two dominant grasses (Agropyron cristatum (L.) Gaertn., Stipa krylovii Roshev.) and two forbs (Artemisia frigida Willd., Potentilla bifurca L.) were analyzed.
Important findings Water addition decreased plant leaf N and P concentrations, whereas N and P addition increased them, indicating that the semi-arid grassland studied suffers from a shortage of N and P supply. Both N and P addition decreased the levels of soluble sugars, starch and thus also NSC in plant leaves, which may be attributed to (i) increased carbohydrate consumption associated with a higher growth rate, and (ii) a dilution effect of greater plant size under N and P addition. Water addition tended to increase the leaf NSC levels both in the grasses (+9.2%) and forbs (+0.6% only), which may be a result of increased photosynthesis of plants with increased water availability. Under conditions of ambient and increased water supply in the present study, N addition resulted in an N/P ratio of>16 in the grasses but a significantly lower N/P ratio of <11 in the forb species. This finding implies that growth of the two grass species will be limited mainly by P availability but the forbs will still be mainly limited by N supply if N deposition, alone or in combination with summer precipitation, continues to increase as predicted in Inner Mongolia.