Abstract

In mixed oak stands situated within two isolated forest reserves in NE Italy, we investigated how plant communities are modulated by local conditions, forest structure and landscape attributes. Species richness and functional dispersion increased towards canals, whereas soil salinity, canopy density or landscape heterogeneity were less relevant. Mean nutrient indicator values increased near canals and with higher proportions of agriculture around. Functional dispersion decreased at wet, nutrient rich sites. Also, the proportion of salt tolerant species increased towards canals, but was unrelated to measures of soil salinity. At sites with more modified landscapes around, widely distributed species were more prevalent, at cost of plants with restricted distributional ranges. Hence, biotic homogenization is fostered inside the reserves through landscape modification in their surroundings. In contrast to species richness, composition turned out to be markedly modulated by environmental variation, with local site factors, forest stand structure and landscape attributes contributing to roughly the same extent. Conservation practices should therefore not only focus on managing local conditions, but also take landscape structure into account. For coastal forests, dry and open, nutrient poor sites are of special conservation concern, which are believed to most closely resemble the original diverse vegetation of these Mediterranean habitats.

摘要

在位于意大利东北部两个孤立的森林保护区中的混合橡树林中，我们调查了植物群落如何因当地条件，森林结构和景观属性而受到调节。物种丰富度和功能扩散向运河增加，而土壤盐分，冠层密度或景观异质性则不那么重要。运河附近和周围农业所占比例较高时，平均营养指标值增加。在潮湿，营养丰富的地方功能分散性降低。同样，耐盐物种的比例向运河增加，但与土壤盐度的测量无关。在周围景观变化更大的地点，分布广泛的物种更为普遍，但代价是分布范围受限制的植物。因此，通过对其周围环境进行景观改造，可以在保护区内促进生物同质化。与物种丰富度相反，事实证明其组成受到环境变化的显着调节，而局部地点因素，林分结构和景观属性的贡献程度大致相同。因此，保护​​实践不仅应侧重于管理当地条件，而且还应考虑景观结构。对于沿海森林而言，干旱和空旷，营养不良的地点特别值得关注，据认为与这些地中海生境的原始多样性植被最为相似。林分结构和景观属性的贡献程度大致相同。因此，保护​​实践不仅应侧重于管理当地条件，而且还应考虑景观结构。对于沿海森林而言，干旱和空旷，营养不良的地点特别值得关注，据认为与这些地中海生境的原始多样性植被最为相似。林分结构和景观属性的贡献程度大致相同。因此，保护​​实践不仅应侧重于管理当地条件，而且还应考虑景观结构。对于沿海森林而言，干旱和空旷，营养不良的地点特别值得关注，据认为与这些地中海生境的原始多样性植被最为相似。