High nitrogen addition induces functional trait divergence of plant community in a temperate desert steppe

• Published in: Plant and soil 2023-06, Vol.487 (1-2), p.133-156
• Main Authors: Qiao, Jingjuan, Zuo, Xiaoan, Yue, Ping, Wang, Shaokun, Hu, Ya, Guo, Xinxin, Li, Xiangyun, Lv, Peng, Guo, Aixia, Sun, Shanshan
• Format: Article
• Language: English
• Subjects: aboveground biomass; Abundance; Agriculture; Analysis; Assembling; Assembly; Barren lands; Biomedical and Life Sciences; carbon; Carbon content; China; Composition; Convergence; Deserts; Differentiation; Divergence; Dry matter; Ecology; Environmental gradient; Filtration; Functionally gradient materials; Leaf area; leaf dry matter content; leaf nitrogen content; leaf thickness; Leaves; Life Sciences; Low income areas; Mathematical analysis; Nitrogen; Plant communities; plant height; Plant Physiology; Plant Sciences; Plants; Polynomials; regression analysis; Research Article; soil; Soil properties; Soil Science & Conservation; Species composition; species diversity; specific leaf area; Steppes; Strategy
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/s11104-023-05910-1

Purpose Nitrogen (N) deposition is well known to affect plant community assembly, but the underlying mechanisms are still poorly understood. How different processes, including environmental and biotic filtering, drive plant community assembly can be quantified by trait range restrictions and patterns of trait convergence and divergence. However, few studies have combined species abundances data to simultaneously explore how these two processes function and further affect community assembly along N addition gradients by progressively examining multiple trait range restrictions and trait patterns. Methods We conducted a four-year N addition experiment with eight N addition levels in a temperate desert steppe, Inner Mongolia. We investigated species composition and then collected aboveground biomass (AGB). In addition, six soil properties and functional traits were measured. Community-weighted trait means (CWM) and community-weighted trait variances (CWV) at eight N addition levels were calculated based on species abundances and their corresponding traits. We quantified environmental filtering as a restriction of trait range, and trait patterns depended on CWV. We calculated the effect size (ES) values of six trait ranges and CWVs by comparing the observed community with two simulated null communities generated by a two-step trait-based approach. Using the one-tailed Wilcoxon signed-ranks tests ( W ) and the Spearman’s rank correlations ( S ) methods, we further explored changes in six trait ranges and trait patterns along experimental N addition gradients by the ES values. Results We found that high N addition altered species composition, and the dominant S-strategy species (conservative species) in high-barren and low-disturbance environments were gradually replaced by R-strategy species (acquisitive species) in low-barren and high-disturbance environments. The polynomial regression showed that AGB was highest at 27 g.m −2 N addition level. The responses of six CWM values under N24 and N48 were significantly different from those under other N addition treatments, and they showed two opposite trends along N addition gradients. The CWM values of three traits (i.e., plant height (H), leaf dry matter content (LDMC) and leaf carbon content (LCC)) significantly decreased, while the CWM values of other three traits (i.e., leaf thickness (LT), specific leaf area (SLA) and leaf nitrogen content (LNC)) significantly increased. The trait range of H, LDMC and LCC was w