Non-linear response of plant caloric value to N addition and mowing treatments in a meadow steppe  

作　　者：Jiaqi Ye Shuai Wu Yu Mo Siqi Yang Yu Zhao Jing Zhang Xiaotao Lü Guojiao Yang Xingguo Han Cunzhu Liang Zhenghai Li Yajing Bao 

机构地区：[1]Key Laboratory of Ecology and Resource Use of the Mongolian Plateau,Ministry of Education of China,Collaborative Innovation Center for Grassland Ecological Security,School of Ecology and Environment,Inner Mongolia University,Hohhot,010021,China [2]College of Environment and Bioresources,Dalian Minzu University,Dalian,116600,China [3]University of Chinese Academy of Sciences,Beijing,100049,China [4]State Key Laboratory of Vegetation and Environmental Change,Institute of Botany,Chinese Academy of Sciences,Beijing,100093,China [5]Erguna Forest-Steppe Ecotone Research Station,Institute of Applied Ecology,Chinese Academy of Sciences,Shenyang,110016,China [6]Key Laboratory of Agro-Forestry Environmental Processes and Ecological Regulation,School of Ecology and Environment,Hainan University,Haikou,570228,China

出　　处：《Ecological Processes》2024年第4期82-98,共17页生态过程(英文)

基　　金：funded by the National Natural Science Foundation of China(grant numbers 31971464 and 32371639);basic research business fees of central universities of China(grant number 0919-140124).

摘　　要：Background Caloric value is an important indicator of grassland ecosystem function,but the response of caloric value to nitrogen(N)addition and mowing is still unclear.We explored the adaptive changes of plant caloric value and energy standing crop along a N addition gradient after six-year NH_(4)NO_(3) addition and mowing treatments in an Inner Mongolian temperate meadow steppe in northern China.Results We found that the response of plant caloric value to N addition at different organizational levels was diverse.The caloric value of legumes increased linearly with N addition rates.The caloric value of grasses exhibited a non-linear response trend,initially increasing followed by saturation or decrease,with a N response threshold present.Due to the dominance of grass species,the caloric value at the community level followed a similar pattern to that of the grasses along the N addition gradient.Under mowing,the caloric value of plants at each organizational level increased and usually mowing enhanced the N response threshold.Amongst these,the N response threshold of Leymus chinensis increased from 3.302 to 5.443 g N m^(−2) yr^(−1),grasses increased from 4.414 to 5.746 g N m^(−2) yr^(−1),and community increased from 5.373 to 9.216 g N m^(−2) yr^(−1).Under non-mowing treatment,the N response thresholds of the most dominant species,Leymus chinensis,and community energy standing crop were 10.001 and 15.119 g N m^(−2) yr^(−1),respectively.Under mowing,the energy standing crops showed a linear increasing trend.Conclusions N response thresholds of plant caloric value and energy standing crop vary at different organizational levels(community>functional group>species).The results reveal varying regulatory capabilities of plants on the ecological environment at different organizational levels.These findings enhance our understanding of plant-environment interactions in grassland ecosystems under N deposition from an energy perspective,which is of great significance to clarify the response mechanism of grassl

关 键 词：N addition MOWING Caloric value Energy standing crop Meadow steppe 

分 类 号：S812[农业科学—草业科学]