Data from: Of niche differentiation, dispersal ability and historical legacies: what drives woody community assembly in recent Mediterranean forests?

Community assembly rules have been extensively studied, but its association with regional environmental variation, while land use history remains largely unexplored. Land use history might be especially important in Mediterranean forests, considering their historical deforestation and recent afforestation. Using forest inventories and historical (1956) and recent (2000) land cover maps, we explored the following hypotheses: 1) woody species assembly is driven by environmental factors, but also by historical landscape attributes; 2) recent forests exhibit lower woody species richness than pre-existing due to the existence of colonization credits; 3) these credits are modulated by species’ life-forms and dispersal mechanisms. We examined the association of forest historical type (pre-existing versus recent) with total species richness and that of diverse life-forms and dispersal groups, also considering the effects of current environment and past landscape factors. When accounting for these effects, no significant differences in woody species richness were found between forest historical types except for vertebrate-dispersed species. Species richness of this group was affected by the interaction of forest historical type with distance to coast and rainfall: vertebrate-dispersed species richness increased with rainfall and distance to the coast in recent forests, while it was higher in dryer sites in pre-existing forests. In addition, forest historical types showed differences in woody species composition associated to diverse environmental and past landscape factors. In view of these results we can conclude that: 1) community assembly in terms of species richness is fast enough to exhaust most colonization credit in recent Mediterranean forests except for vertebrate-dispersed species; 2) for these species, colonization credit is affected by the interplay of forest history and a set of proxies of niche and landscape constraints of species dispersal and establishment; 3) woody species assemblage is mostly shaped by the species’ ecological niches in these forests.

群落构建规则（community assembly rules）已得到广泛研究，但土地利用历史与区域环境变异之间的关联尚未得到充分探索。考虑到地中海森林（Mediterranean forests）曾历经历史森林砍伐与近期人工造林活动，土地利用历史对其可能具有尤为重要的影响。本研究依托森林清查数据、1956年历史土地覆盖图与2000年近期土地覆盖图，对以下三项假说展开验证：其一，木本植物（woody species）的群落构建同时受环境因素与历史景观属性驱动；其二，受定植信用（colonization credit）效应影响，新生林的木本植物物种丰富度低于原生林；其三，定植信用受物种生活型与扩散机制的调控。我们分析了森林历史类型（原生林与新生林）与总物种丰富度、不同生活型及扩散类群物种丰富度之间的关联，同时纳入当前环境与历史景观因子的影响进行考量。在控制上述变量后，两类森林的木本植物总物种丰富度未呈现显著差异，但脊椎动物扩散型物种（vertebrate-dispersed species）除外。该类群的物种丰富度受森林历史类型与距海岸距离、降雨量的交互作用影响：在新生林中，脊椎动物扩散型物种丰富度随降雨量增加与距海岸距离增大而升高；而在原生林中，该类群的物种丰富度在更为干旱的生境中更高。此外，两类森林的木本植物群落组成存在差异，且这种差异与多种环境及历史景观因子相关。基于上述研究结果，我们可得出以下结论：第一，就物种丰富度而言，地中海森林中的群落构建过程足够快速，可耗尽新生林中的大部分定植信用，脊椎动物扩散型物种除外；第二，对于该类物种，定植信用受森林历史与一系列代表物种扩散与定植过程的生态位（ecological niches）及景观限制因子的交互作用调控；第三，在上述森林中，木本植物群落的构建主要由物种生态位塑造。