Debaba Gossaye Hailu, Li Kunyu, Wang Xiaowei, Wang Yanan, Bai Wenming, Li Guoyong
International Joint Research Laboratory for Global Change Ecology, School of Life Sciences, Henan University, Kaifeng 475004, China.
State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
Biology (Basel). 2024 Jul 23;13(8):554. doi: 10.3390/biology13080554.
Nitrogen (N) deposition, as one of the global change drivers, can alter terrestrial plant diversity and ecosystem function. However, the response of the plant diversity-ecosystem function relationship to N deposition remains unclear. On one hand, in the previous studies, taxonomic diversity (i.e., species richness, SR) was solely considered the common metric of plant diversity, compared to other diversity metrics such as phylogenetic and functional diversity. On the other hand, most previous studies simulating N deposition only included two levels of control versus N enrichment. How various N deposition rates affect multidimensional plant diversity-ecosystem function relationships is poorly understood. Here, a field manipulative experiment with a N addition gradient (0, 1, 2, 4, 8, 16, 32, and 64 g N m yr) was carried out to examine the effects of N addition rates on the relationships between plant diversity metrics (taxonomic, phylogenetic, and functional diversity) and ecosystem production in a temperate steppe. Production initially increased and reached the maximum value at the N addition rate of 47 g m yr, then decreased along the N-addition gradient in the steppe. SR, functional diversity calculated using plant height (FDis-Height) and leaf chlorophyll content (FDis-Chlorophyll), and phylogenetic diversity (net relatedness index, NRI) were reduced, whereas community-weighted means of plant height (CWM) and leaf chlorophyll content (CWM) were enhanced by N addition. N addition did not affect the relationships of SR, NRI, and FDis-Height with production but significantly affected the strength of the correlation between FDis-Chlorophyll, CWM, and CWM with biomass production across the eight levels of N addition. The findings indicate the robust relationships of taxonomic and phylogenetic diversity and production and the varying correlations between functional diversity and production under increased N deposition in the temperate steppe, highlighting the importance of a trait-based approach in studying the plant diversity-ecosystem function under global change scenarios.
氮（N）沉降作为全球变化驱动因素之一，能够改变陆地植物多样性和生态系统功能。然而，植物多样性与生态系统功能关系对氮沉降的响应仍不明确。一方面，在以往的研究中，与系统发育多样性和功能多样性等其他多样性指标相比，分类学多样性（即物种丰富度，SR）被单独视为植物多样性的常用指标。另一方面，以往大多数模拟氮沉降的研究只包括对照与氮富集两个水平。不同氮沉降速率如何影响多维植物多样性与生态系统功能关系仍知之甚少。在此，开展了一项氮添加梯度（0、1、2、4、8、16、32和64 g N m² yr⁻¹）的田间控制实验，以研究氮添加速率对温带草原植物多样性指标（分类学、系统发育和功能多样性）与生态系统生产力之间关系的影响。在温带草原中，生产力最初增加，并在氮添加速率为47 g m² yr⁻¹时达到最大值，然后沿氮添加梯度下降。氮添加降低了物种丰富度、基于株高计算的功能多样性（FDis-Height）和叶片叶绿素含量计算的功能多样性（FDis-Chlorophyll）以及系统发育多样性（净亲缘关系指数，NRI），而氮添加提高了植物株高的群落加权均值（CWM）和叶片叶绿素含量的群落加权均值（CWM）。氮添加并未影响物种丰富度、净亲缘关系指数和基于株高计算的功能多样性与生产力之间的关系，但在八个氮添加水平上显著影响了基于叶片叶绿素含量计算的功能多样性、株高群落加权均值和叶绿素含量群落加权均值与生物量生产力之间的相关强度。研究结果表明，在温带草原氮沉降增加的情况下，分类学和系统发育多样性与生产力之间存在稳健的关系，功能多样性与生产力之间的相关性各不相同，这突出了基于性状的方法在研究全球变化情景下植物多样性与生态系统功能关系中的重要性。
