刈割与施肥干扰下高寒草甸植物功能性状的构建模式

Assembly patterns of plant functional traits in alpine meadow under disturbances by mowing and fertilization

针对目前关于植物群落功能性状构建模式及其驱动因素存在的争议,研究了33个物种10个功能性状的构建模式。研究结果显示:(1)在刈割-施肥复合梯度上,这些功能性状主要表现为随机构建模式,发生随机性和确定性构建的样方比例分别为82.7%和17.3%;(2)在10个功能性状中,生长型、生活周期、单株地上干质量、叶面积和叶干质量5个功能性状为随机构建模式,不受试验处理和群落特征(地上净初级生产力、刈割生物量损失、群落高度)变化的影响。植物倾斜度、繁殖方式、固氮性、株高和比叶面积5个功能性状的构建模式与试验处理或群落特征变化有关,表现出趋同或趋异构建响应。其中,植物倾斜度和比叶面积的构建模式仅受群落特征影响,而固氮性、繁殖方式和株高3个性状的构建模式同时还受刈割或施肥处理的影响,其构建模式因功能性状而异;(3)群落的生物量损失和地上净初级生产力是解释植物功能性状构建模式变化较理想的群落特征;(4)刈割和施肥处理对株高的构建模式具有相反效应,而刈割和施肥的交互作用对其无显著影响。上述结果说明该研究群落植物功能性状的构建存在不同模式,以随机构建模式为主,确定性构建模式居次要地位。确定性构建模式与试验处理和群落特征变化有关,而且是性状依赖的。相反选择力对趋同和趋异构建模式的平衡效应能引起功能性状发生随机构建。

Aims Fully understanding the assembly patterns of plant functional traits in plant communities is a big challenge in the study of community ecology. The assembly patterns in alpline meadow and driving factors are still poorly known. In this study, experiments with different mowing intensities and various treatments of fertilization were conducted in alpline meadow for the purpose of improving the understanding of the assembly patterns of plant functional traits in plant community.Methods Data on functional diversity of 10 traits for 33 species from 108 quadrats （with varying combinations of mowing and fertilization） were analyzed by randomizations tests, ANCOVA and regression analysis, respectively, for the trait convergence/divergence.Important findings None of the traits studied showed consistently significant convergence or divergence pattern in integral gradients of fertilization and mowing treatments, while the ratios of quadrats assembled under deterministic and stochastic processes were 82.7% and 17.3%, respectively. Among the functional traits tested, growth form, life cycle, aboveground dry mass per plant, leaf area and leaf dry mass showed a stochastic pattern of as- sembly, but they were not affected by variations in mowing treatments and community characteristics （i.e. aboveground net primary productivity, biomass loss and vegetation height）. Convergence or divergence patterns were shown in traits such as plant inclination, reproductive modes, nitrogen fixation, plant height and specific leaf area, which were affected by variations in mowing treatments and community characteristics. Among them, assembly patterns of plant inclination and specific leaf area were only affected by community characteristics, while nitrogen fixation, reproductive modes and plant height were affected by both mowing treatments and community charac- teristics. Moreover, the patterns of assembly varied by traits. Aboveground net primary productivity and biomass loss well explained variations in the assembly pattem of plant functional traits. Mowing and fertilization showed the reversed effects on the assembly pattern of plant height, while no significant interaction was found between mowing and fertilization. The results suggested that there were different assembly pattems of functional traits in the community： stochastic pattern of assembly was the primary, and the deterministic pattern was secondary. Deterministic pattern was trait-dependent and correlated with variations in mowing treatments and community characteristics. The balancing effect of opposite selection forces, on the other hand, could lead to stochastic assembly patterns in plant functional traits.