Decisive environmental characteristics for woody regrowth in forest edges - Patterns along complex environmental gradients in Southern Sweden

摘要

Early and late successional stages of forest edge development were studied across long, complex environmental gradients in order to disentangle and assess the woody species composition and functional traits' relations to abiotic and biotic environmental characteristics at site and landscape scale. Data were sampled from 78 randomly stratified locations along a 610-km railway corridor between the cities of Stockholm and Malmo, Sweden, and subsequently analysed in multiple steps of unconstrained, constrained and partial constrained ordination and variation partitioning. Different analytical methods were applied at each step and only the environmental characteristics that repeatedly showed significant impacts on woody species composition were selected for analysis of average weighted community traits to provide verification and a more detailed understanding. Following this approach, 10 environmental characteristics were identified as decisive for the woody species composition of the forest edges. The variation partitioning revealed a marked shift in the relative explanatory power of the environmental variables in relation to the succession of the forest edges. In the early successional stage, the abiotic variables related to site productivity (as reflected by field layer type and soil moisture) and climate (humidity and altitude) dominate, while in the late successional stages of forest edges more complex patterns evolved due to hierarchical and dynamic filter effects, where biotic variables reflecting structural aspects at site (forest edge profile, canopy stratification and canopy cover) and landscape (forest continuity and the shape and contrast of edges in the surrounding landscape) level were equally important as the abiotic variables. We concluded that management efforts in early succession stages of forest edges should depart from basic abiotic gradients of site fertility and moisture; and that it is crucial to incorporate vegetation structure variables at site and landscape level into long-term management planning. (C) 2015 Elsevier B.V. All rights reserved.