Kopecký Martin, Hédl Radim, Szabó Péter
Department of Vegetation Ecology, Institute of Botany, Academy of Sciences of the Czech Republic, Lidická 25/27, CZ-602 00 Brno, Czech Republic.
Department of Botany, Faculty of Science, Charles University in Prague, Benátská 2, CZ-128 01 Prague, Czech Republic.
J Appl Ecol. 2013 Feb;50(1):79-87. doi: 10.1111/1365-2664.12010.
The plant community structure of European lowland forests has changed dramatically in the 20 century, leading to biodiversity decline at various spatial scales. However, due to methodological difficulties associated with simultaneous changes in species diversity and composition, ecological processes behind the changes are still poorly understood. We analysed temporal changes in forest plant community after the mid-20 century abandonment of coppicing in a typical Central European forest, which had been managed as coppice for centuries. We used 122 semi-permanent plots first surveyed in the 1950s shortly after the last coppicing and again in the 2000s after half a century of natural succession. We used a novel Temporal Nestedness Analysis to disentangle the immigration and extinction processes underlying temporal changes in community structure and tested whether species gains and losses were ecologically random. The studied vegetation has shifted from the species-rich assemblages of a relatively open and low-nutrient forest towards the impoverished flora of a closed-canopy forest dominated by a few shade-adapted species. The significant reduction of beta diversity, i.e. compositional heterogeneity among plots, indicated taxonomic homogenization of the forest understorey. Temporal species turnover was only a minor component of the community change and recent assemblages are nested subsets of the former ones. Ecologically non-random extinctions dominated these changes. Light-demanding species with a persistent seed-bank were the most prone to extinction, while species with high specific leaf area substantially increased in frequency. The dominant process after the abandonment of coppicing was the ecologically non-random extinction of light-demanding species leading to an impoverished, temporally nested plant community structure. This development is typical for many abandoned lowland coppice forests and poses a significant threat to forest biodiversity in Europe. If forestry and conservation policies continue to prefer closed-canopy stands, many endangered species are likely to pay their extinction debts. To restore declining or even locally extinct species, canopy opening in abandoned coppices is urgently needed.
20世纪,欧洲低地森林的植物群落结构发生了巨大变化,导致不同空间尺度上的生物多样性下降。然而,由于物种多样性和组成同时发生变化所带来的方法学困难,这些变化背后的生态过程仍知之甚少。我们分析了20世纪中叶中欧一片典型森林停止矮林作业后森林植物群落的时间变化,这片森林已经进行了数百年的矮林经营。我们使用了122个半永久性样地,这些样地在20世纪50年代最后一次矮林作业后不久首次进行调查,并在经过半个世纪自然演替后的21世纪再次进行调查。我们使用了一种新颖的时间嵌套分析来理清群落结构时间变化背后的迁入和灭绝过程,并测试物种的增减是否在生态上是随机的。所研究的植被已从相对开阔、低养分森林中物种丰富的组合转变为以少数耐荫物种为主的封闭树冠森林中较为贫乏的植物区系。β多样性的显著降低,即样地间组成异质性的降低,表明森林下层在分类学上趋于同质化。时间上的物种更替只是群落变化的一个次要组成部分,近期的组合是前者的嵌套子集。生态上非随机的灭绝主导了这些变化。具有持久种子库的喜光物种最容易灭绝,而比叶面积高的物种频率大幅增加。停止矮林作业后的主要过程是喜光物种在生态上非随机的灭绝,导致植物群落结构变得贫乏且在时间上呈嵌套状。这种发展在许多废弃的低地矮林森林中很典型,对欧洲森林生物多样性构成了重大威胁。如果林业和保护政策继续倾向于封闭树冠林分,许多濒危物种可能会偿还它们的灭绝债务。为了恢复数量减少甚至局部灭绝的物种,迫切需要在废弃矮林中进行树冠开口作业。