Effects of N on Plant Response to Heat-wave:A Field Study with Prairie Vegetation

作     者：Dan Wang Scott A. Heckathorn Kumar Mainali E. William Hamilton 

作者机构：Department of Environmental Sciences University of Toledo Toledo Ohio 43606 USA Department of Biology Washington and Lee University Lexington Virginia 24450 USA 

出 版 物：《Journal of Integrative Plant Biology》 (植物学报（英文版）)

年 卷 期：2008年第50卷第11期

页      面：1416-1425页

核心收录：

学科分类：090503[农学-草业科学] 0909[农学-草学] 07[理学] 0905[农学-畜牧学] 070602[理学-大气物理学与大气环境] 09[农学] 0903[农学-农业资源与环境] 0706[理学-大气科学] 

基　　金：Supported by a Grant from the National Science Foundation to S. A.Heckathorn and E. W. Hamilton 

主　　题：global climate change heat stress N resorption rate photosynthesis photosynthetic N-use efficiency. 

摘      要：More intense, more frequent, and longer heat-waves are expected in the future due to global warming, which could have dramatic ecological impacts. Increasing nitrogen （N） availability and its dynamics will likely impact plant responses to heat stress and carbon （C） sequestration in terrestrial ecosystems. This field study examined the effects of N availability on plant response to heat-stress （HS） treatment in naturally-occurring vegetation. HS （5 d at ambient or 40.5 ℃） and N treatments （±N） were applied to 16 1 m^2 plots in restored prairie vegetation dominated by Andropogon gerardii （warm-season C4 grass） and Solidago canadensis （warm-season C3 forb）. Before, during, and after HS, air, canopy, and soil temperature were monitored; net CO2 assimilation （Pn）, quantum yield of photosystem Ⅱ （ФpsⅡ）, stomatal conductance （gs）, and leaf water potential （ψw） of the dominant species and soil respiration （Rsoll） of each plot were measured daily during HS. One week after HS, plots were harvested, and C% and N% were determined for rhizosphere and bulk soil, and above-ground tissue （green/senescent leaf, stem, and flower）. Photosynthetic N-use efficiency （PNUE） and N resorption rate （NRR） were calculated. HS decreased Pn, gs, ψw, and PNUE for both species, and ＋N treatment generally increased these variables （±HS）, but often slowed their post-HS recovery. Aboveground biomass tended to decrease with HS in both species （and for green leaf mass in S. canadensis）, but decrease with ＋N for A. gerardii and increase with ＋N for S. canadensis. For A. gerardii, HS tended to decrease N% in green tissues with ＋N, whereas in S. canadensis, HS increased N% in green leaves. Added N decreased NRR for A. gerardii and HS increased NRR for S. canadensis. These results suggest that heat waves, though transient, could have significant effects on plants, communities, and ecosystem N cycling, and N can influence the effect of heat waves.