Community assembly along a soil depth gradient: contrasting patterns of plant trait convergence and divergence in a Mediterranean rangeland
Community assembly along a soil depth gradient: contrasting patterns of plant trait convergence and divergence in a Mediterranean rangeland
复制标题
DOI：
10.1111/1365-2745.12003
复制
发表时间：
2012-11-01
影响因子：
5.5
通讯作者：
Garnier, Eric
中科院分区：
文献类型：
--
作者：
Bernard-Verdier, Maud;Navas, Marie-Laure;Garnier, Eric
了解环境因素如何驱动植物群落组装仍然是社区生态学的一个重大挑战。不同的组装过程沿着环境梯度的强度，如环境过滤和功能生态位分化，可以通过分析社区的性状分布进行量化。虽然环境过滤影响物种的出现在社区之间，功能的分歧或收敛是密切相关的社区内的物种丰度，很少有研究考虑到。我们研究的特质介导的影响，这两个过程沿着压力资源梯度。我们测量了物种丰富度和八个特征的分布与植物群落的营养和再生阶段沿着梯度的土壤深度和资源的可用性在地中海牧场。我们量化的环境过滤，定义为一个本地的限制性状范围，和性状分歧，基于丰度加权性状方差，使用两步的方法与专门设计的空模型。社区提出了一个明确的功能响应，土壤梯度，证明了社区加权性状手段的强烈趋势。我们检测到的梯度两端的不同性状的环境过滤，这表明，与广泛的预期相反，性状过滤可能不一定是非生物过滤的结果，在恶劣的条件下，但也可能导致生物在生产性栖息地的相互作用。我们发现，显着的变化，性状丰富度分布在社区内沿着梯度。植被特征（如叶干物质含量）分歧浅的土壤，反映了不同的水和养分的使用策略，在这些受限制的栖息地共存，并与土壤资源的可用性增加收敛。与此相反，再生性状（如种子质量）倾向于分歧向更深的土壤，而植物生殖高度分歧所有沿着梯度。合成法：我们的研究强调了如何将丰度数据与捕获不同功能小生境的性状相结合，对于检测植物群落对环境梯度的复杂功能反应至关重要。我们表明，性状分歧和过滤模式是强烈的偶然的性状和环境，这样就不能有一个简单的趋势，增加或减少功能分歧沿着梯度的资源可用性的期望。
Understanding how environmental factors drive plant community assembly remains a major challenge in community ecology. The strength of different assembly processes along environmental gradients, such as environmental filtering and functional niche differentiation, can be quantified by analysing trait distributions in communities. While environmental filtering affects species occurrence among communities, functional divergence or convergence is strongly related to species abundances within communities, which few studies have taken into account. We examine the trait-mediated effect of these two processes along a stress-resource gradient. We measured species abundances and the distributions of eight traits related to vegetative and regenerative phases in plant communities along a gradient of soil depth and resource availability in Mediterranean rangelands. We quantified environmental filtering, defined as a local restriction of trait range, and trait divergence, based on abundance-weighted trait variance, using a two-step approach with specifically designed null models. Communities presented a clear functional response to the soil gradient, as evidenced by strong trends in community-weighted trait means. We detected environmental filtering of different traits at both ends of the gradient, suggesting that, contrary to widespread expectations, trait filtering may not necessarily be the result of abiotic filtering under harsh conditions but could likely also result from biotic interactions in productive habitats. We found marked shifts in trait abundance distributions within communities along the gradient. Vegetative traits (e.g. leaf dry matter content) diverged on shallow soils, reflecting the coexistence of distinct water- and nutrient-use strategies in these constrained habitats and converged with increasing soil resource availability. By contrast, regenerative traits (e.g. seed mass) tended to diverge towards deeper soils, while plant reproductive heights diverged all along the gradient. Synthesis: Our study highlights how the combination of abundance data with traits capturing different functional niches is critical to the detection of complex functional responses of plant communities to environmental gradients. We demonstrate that patterns of trait divergence and filtering are strongly contingent on both trait and environment such that there can be no expectation of a simple trend of increasing or decreasing functional divergence along a gradient of resource availability.