Responses and sensitivity of N, P and mobile carbohydrates of dominant species to increased water

Xue Wang1,2, Zhuwen Xu1, Caifeng Yan1, Wentao Luo1,2,Ruzhen Wang1,2, Xingguo Han1, Yong Jiang1,*   2017-07-04 23:26:08

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

*Correspondence address. Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, No. 72 Wenhua Road, Shenhe District, Shenyang 110016, China.Tel: +86 24 83970902; Fax: +86 24 83970300; E-mail: jiangyong@iae.ac.cn

Journal of Plant Ecology

VOLUME 10, NUMBER 3,PAGES 486–496

June 2017

doi: 10.1093/jpe/rtw053

Advance Access publication 28 May 2016

available online at academic.oup.com/jpe

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.

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

Received: 9 July 2015, Revised: 18 May 2016, Accepted: 24 May 2016

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