Data from: Land-use intensification effects on functional properties in tropical plant communities

There is consensus that plant diversity and ecosystem processes are negatively affected by land-use intensification (LUI), but, at the same time, there is empirical evidence that a large heterogeneity can be found in the responses. This heterogeneity is especially poorly understood in tropical ecosystems. We evaluated changes in community functional properties across five common land-use types in the wet tropics with different land-use intensity: mature forest, logged forest, secondary forest, agricultural land, and pastureland, located in the lowlands of Bolivia. For the dominant plant species, we measured 12 functional response traits related to their life history, acquisition and conservation of resources, plant domestication, and breeding. We used three single-trait metrics to describe community functional properties: community abundance-weighted mean (CWM) traits values, coefficient of variation, and kurtosis of distribution. The CWM of all 12 traits clearly responded to LUI. Overall, we found that an increase in LUI resulted in communities dominated by plants with acquisitive leaf trait values. However, contrary to our expectations, secondary forests had more conservative trait values (i.e., lower specific leaf area) than mature and logged forest, probably because they were dominated by palm species. Functional variation peaked at intermediate land-use intensity (high coefficient of variation and low kurtosis), which included secondary forest but, unexpectedly, also agricultural land, which is an intensely managed system. The high functional variation of these systems is due to a combination of how response traits (and species) are filtered out by biophysical filters and how management practices introduced a range of exotic species and their trait values into the local species pool. Our results showed that, at local scales and depending on prevailing environmental and management practices, LUI does not necessarily result in communities with more acquisitive trait values or with less functional variation. Instead of the widely expected negative impacts of LUI on plant diversity, we found varying responses of functional variation, with possible repercussions on many ecosystem services. These findings provide a background for actively mitigating negative effects of LUI while meeting the needs of local communities that rely mainly on provisioning ecosystem services for their livelihoods.学界普遍认为，土地利用集约化（land-use intensification, LUI）会对植物多样性（plant diversity）与生态系统服务（ecosystem services）产生负面影响，但与此同时，已有实证研究表明，不同生态系统的响应存在显著异质性。这种异质性在热带生态系统（tropical ecosystems）中尤其缺乏深入认知。我们针对玻利维亚低地湿热带区域内五种土地利用强度各异的常见土地利用类型——成熟林、采伐林、次生林、农用地与牧草地，开展了群落功能属性变化的评估工作。针对优势植物物种，我们测定了12项与植物生活史（life history）、资源获取与保存、植物驯化（plant domestication）及育种（breeding）相关的功能响应性状（functional response traits）。我们采用三项单性状指标（single-trait metrics）来描述群落功能属性：群落多度加权均值（community abundance-weighted mean, CWM）性状值、变异系数以及分布峰度（kurtosis of distribution）。所有12项性状的CWM均显著响应土地利用集约化。总体而言，我们发现土地利用集约化程度提升会使得群落被具有资源获取型叶片性状（leaf trait）的植物所主导。但与我们的预期相悖的是，次生林的叶片性状值相较于成熟林与采伐林更为保守，即比叶面积（specific leaf area）更低，这可能是因为次生林以棕榈科植物为优势类群。功能变异（functional variation）在中等土地利用强度下达到峰值，即变异系数较高、峰度较低，其中既包含次生林，同时也包含意料之外的农用地——这是一种高强度管理的人工系统。这类系统的高功能变异源于两个因素：一是生物物理过滤（biophysical filters）对响应性状（及物种）的筛选作用，二是管理实践将一系列外来物种（exotic species）及其性状值引入本地物种种库（local species pool）。我们的研究结果表明，在局域尺度下，结合当前的环境条件与管理实践，土地利用集约化未必会催生以资源获取型性状占优的群落，也未必会导致功能变异更低的群落。相较于学界普遍预期的土地利用集约化对植物多样性的负面影响，我们发现功能变异存在多样化的响应模式，这可能对诸多生态系统服务产生潜在影响。这些研究结果可为主动缓解土地利用集约化的负面影响提供理论支撑，同时能够满足主要依赖供给型生态系统服务（provisioning ecosystem services）维持生计的本地社区的发展需求。