School of Forestry and Environmental Studies, Yale University, 195 Prospect Street, New Haven, Connecticut, 06511, USA.
Department of Biology and the Ecology Center, Utah State University, 5305 Old Main Hill, Logan, Utah, 84322, USA.
Ecol Appl. 2018 Dec;28(8):2142-2152. doi: 10.1002/eap.1802. Epub 2018 Oct 17.
Environment and human land use both shape forest composition. Abiotic conditions sift tree species from a regional pool via functional traits that influence species' suitability to the local environment. In addition, human land use can modify species distributions and change functional diversity of forests. However, it is unclear how environment and land use simultaneously shape functional diversity of tree communities. Land-use legacies are especially prominent in temperate forest landscapes that have been extensively modified by humans in the last few centuries. Across a 900-ha temperate deciduous forest in the northeastern United States, comprising a mosaic of different-aged stands due to past human land use, we used four key functional traits-maximum height, rooting depth, wood density, and seed mass-to examine how multiple environmental and land-use variables influenced species distributions and functional diversity. We sampled ~40,000 trees >8 cm DBH within 485 plots totaling 137 ha. Species within plots were more functionally similar than expected by chance when we estimated functional diversity using all traits together (multi-trait), and to a lesser degree, with each trait separately. Multi-trait functional diversity was most strongly correlated with distance from the perennial stream, elevation, slope, and forest age. Environmental and land-use predictors varied in their correlation with functional diversities of the four individual traits. Landscape-wide change in abundances of individual species also correlated with both environment and land-use variables, but magnitudes of trait-environment interactions were generally stronger than trait interactions with land use. These findings can be applied for restoration and assisted regeneration of human-modified temperate forests by using traits to predict which tree species would establish well in relation to land-use history, topography, and soil conditions.
环境和人类土地利用都会影响森林组成。非生物条件通过影响物种对当地环境适应性的功能特征，从区域物种库中筛选树种。此外，人类土地利用可以改变物种分布并改变森林的功能多样性。然而，环境和土地利用如何同时塑造树木群落的功能多样性尚不清楚。土地利用遗产在过去几个世纪中人类广泛改造的温带森林景观中尤为突出。在美国东北部的一个 900 公顷的温带落叶林中，由于过去的人类土地利用，形成了不同年代的斑块镶嵌体，我们使用了四个关键的功能特征——最大高度、根系深度、木材密度和种子质量——来研究多种环境和土地利用变量如何影响物种分布和功能多样性。我们在 485 个总面积为 137 公顷的样地中，对 40,000 多棵 >8cmDBH 的树木进行了采样。当我们使用所有特征一起（多特征）估计功能多样性时，样地内的物种在功能上比随机预期更为相似，在单独使用每个特征时也是如此。多特征功能多样性与离永久性溪流的距离、海拔、坡度和森林年龄的相关性最强。环境和土地利用预测因子与四个单独特征的功能多样性的相关性各不相同。个别物种的景观范围丰度变化也与环境和土地利用变量相关，但特征与环境的相互作用的幅度通常大于特征与土地利用的相互作用。这些发现可应用于受人类改造的温带森林的恢复和辅助再生，通过使用特征来预测与土地利用历史、地形和土壤条件有关的哪些树种将能很好地建立。
