{"title":"Non-linear response of plant caloric value to N addition and mowing treatments in a meadow steppe","authors":"Jiaqi Ye, Shuai Wu, Yu Mo, Siqi Yang, Yu Zhao, Jing Zhang, Xiaotao Lü, Guojiao Yang, Xingguo Han, Cunzhu Liang, Zhenghai Li, Yajing Bao","doi":"10.1186/s13717-024-00544-2","DOIUrl":null,"url":null,"abstract":"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 NH4NO3 addition and mowing treatments in an Inner Mongolian temperate meadow steppe in northern China. 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. 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 grassland ecosystem structure and function to N deposition.","PeriodicalId":11419,"journal":{"name":"Ecological Processes","volume":null,"pages":null},"PeriodicalIF":4.6000,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Ecological Processes","FirstCategoryId":"93","ListUrlMain":"https://doi.org/10.1186/s13717-024-00544-2","RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ECOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
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 NH4NO3 addition and mowing treatments in an Inner Mongolian temperate meadow steppe in northern China. 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. 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 grassland ecosystem structure and function to N deposition.
热量值是衡量草原生态系统功能的重要指标,但热量值对氮素添加和刈割的响应尚不清楚。我们探讨了在中国北方内蒙古温带草甸草原上,经过六年的NH4NO3添加和刈割处理后,植物热量值和常温作物能量在氮添加梯度上的适应性变化。我们发现,植物热值对不同组织水平氮添加量的响应是多样的。豆科植物的热值随着氮添加量的增加而线性增加。禾本科植物的热量值呈现非线性响应趋势,最初增加,随后饱和或减少,存在氮响应阈值。由于禾本科物种占优势,群落层面的热量值与禾本科物种的热量值在氮添加梯度上的模式相似。在刈割的情况下,每个组织水平的植物热量值都会增加,通常刈割会提高氮反应阈值。其中,禾本科植物的氮响应阈值从 3.302 g N m-2 yr-1 提高到 5.443 g N m-2 yr-1,禾本科植物从 4.414 g N m-2 yr-1 提高到 5.746 g N m-2 yr-1,群落从 5.373 g N m-2 yr-1 提高到 9.216 g N m-2 yr-1。在非刈割处理下,最优势物种禾本科植物和群落常绿能源作物的氮响应阈值分别为 10.001 和 15.119 g N m-2 yr-1。在刈割条件下,立地能源作物的氮响应阈值呈线性上升趋势。在不同的组织水平(群落 > 功能群 > 物种)上,植物热量值和常温作物能量的氮响应阈值各不相同。这些结果揭示了植物在不同组织水平上对生态环境的不同调控能力。这些发现从能量角度加深了我们对氮沉降条件下草地生态系统中植物与环境相互作用的理解,对阐明草地生态系统结构和功能对氮沉降的响应机制具有重要意义。
期刊介绍:
Ecological Processes is an international, peer-reviewed, open access journal devoted to quality publications in ecological studies with a focus on the underlying processes responsible for the dynamics and functions of ecological systems at multiple spatial and temporal scales. The journal welcomes manuscripts on techniques, approaches, concepts, models, reviews, syntheses, short communications and applied research for advancing our knowledge and capability toward sustainability of ecosystems and the environment. Integrations of ecological and socio-economic processes are strongly encouraged.