Chin J Plant Ecol ›› 2013, Vol. 37 ›› Issue (7): 591-600.DOI: 10.3724/SP.J.1258.2013.00061

Special Issue: 稳定同位素生态学

• Research Articles •     Next Articles

Response of Rumex dentatus foliar nitrogen and its allocation to altitudinal gradients along Balang Mountain, Sichuan, China

FENG Qiu-Hong1,2,CHENG Rui-Mei1,SHI Zuo-Min1,*(),LIU Shi-Rong1,WANG Wei-Xia1,LIU Xing-Liang2,HE Fei2   

  1. 1Key Laboratory on Forest Ecology and Environmental Sciences of State Forestry Administration, Institute of Forest Ecology, Environment and Protection, Chinese Academy of Forestry, Beijing 100091, China
    2Sichuan Academy of Forestry, Chengdu 610081, China
  • Received:2012-12-28 Accepted:2013-06-04 Online:2013-07-01 Published:2013-07-05
  • Contact: SHI Zuo-Min

Abstract:

Aims As a key element in plant tissue, nitrogen plays an important role in the growth and development of plants. Our objective is to determine (1) how both leaf nitrogen and its allocation between photosynthetic and non-photosynthetic systems have responded to an altitudinal gradient and (2) what role their response has played in the adaptation of Rumex dentatus to its changed environment along the altitudinal gradient.
Methods We measured foliar parameters of photosynthesis, diffusional conductance to CO2, stable carbon isotope ratio (δ13C), nitrogen content and specific leaf area (SLA) of the forb R. dentatus in four sites with different altitudes (2350, 2700, 3150 and 3530 m) in the Wolong Reserve. One-way ANOVA was used to find the differences for all parameters among R. dentatus plants from different altitudes, and standardized major axis (SMA) was used to determine the relationships among some main parameters.
Important findings Leaf nitrogen content per area (Narea) increased as maximum photosynthetic capacity (Amax) increased with altitude in R. dentatus. Increased diffusional conductance also had a positive effect on increased photosynthetic capacity with altitude. These may be the result of adaptation of plants to a shortened leaf lifespan caused by low temperature at high altitude. Along with the altitudinal gradient, nitrogen and diffusional conductance of R. dentatus have an indirect effect on foliar δ13C through acting on the ratio of chloroplast partial pressure of CO2 to ambient CO2 partial pressure (Pc/Pa). Compared with diffusional conductance, nitrogen (or carboxylation capacity based on nitrogen) played a more important role in the process, in order to increase foliar δ13C with altitude. Rumex dentatus allocated more nitrogen to build defensive structural tissue with increased altitude. This is why SLA and photosynthetic nitrogen use efficiency (PNUE) decreased with altitude. In the photosynthetic system, more nitrogen was allocated to light-harvesting components in order that enhanced light resource was used preferably by R. dentatus, and then photosynthetic capacity was increased with altitude. Nitrogen and its allocation among systems (especially between photosynthetic and non-photosynthetic systems) are the keys to the adaptation and the response of R. dentatus to the gradient in altitude.

Key words: altitudinal response, nitrogen allocation in leaf, Rumex dentatus, Wolong Reserve