Effects of age and distance on the composition of mixed deciduous forest fragments in an agricultural landscape

Abstract

Abstract. Forest patches in central Belgium were inventoried twice for the presence or absence of forest plant species to study the effects of age and distance on species composition. All forests in the study area were subdivided based on their land use history. To avoid effects of autocorrelated environmental characteristics on species composition, habitat homogeneity was indirectly investigated using a TWINSPAN classification of the vegetation data. Two major habitats (alluvial and non‐alluvial forests) were distinguished and analysed separately. Patterns of species composition were investigated at the landscape level using Mantel tests. Species composition similarity measures were calculated between all pairs of fragments based on the floristic data. A highly significant correlation was found between species composition similarity and inter‐patch distance. Difference in age, which we used as a measure for habitat quality, was less important in explaining species composition patterns. The effects of spatial configuration became significant when difference in age was accounted for, and a partial correlation was calculated between inter‐patch distance and species composition similarity. Different results were found for alluvial and non‐alluvial forest types. Alluvial forests were more influenced by the spatial configuration than the non‐alluvial. For the non‐alluvial forest type effects measured with the difference in age between forest fragments obscured the effects of inter‐patch distance. Based on our findings we suggest that species composition is not only internally generated, but external processes such as differential colonization caused by varying degrees of isolation may be of overriding importance.

The effects of urban or rural landscape context and distance from the edge on native woodland plant communities

“…Agricultural activities and deposition of air pollutants are also often involved in nitrogen enrichment (Honnay et al 2002;Piessens et al 2006;Willi et al 2005). Again, both higher nitrogen deposition in urban areas (Lovett et al 2000) and landuse history (Jacquemyn et al 2001) could be involved. Also, higher N mineralization rates have been observed in urban than in rural forests (McDonnell et al 1993).…”

“…Many studies have focused on the influence of edges on the distribution of forest plant species but mainly in a rural context (Brunet 2007;Honnay et al 1999aHonnay et al , 1999cHonnay et al , 2002Jacquemyn et al 2001;Kolb and Dieckmann 2004). The degree of edge influence depends on edge characteristics (i.e.…”

Comparação de duas metodologias multivariadas no estudo de similaridade entre fragmentos de Floresta Atlântica

“…Jacquemyn et al (2001) também observaram que a similaridade florística diminuía com o aumento da distância entre as áreas, em concordância com as idéias de Condit (1998) citado por Cook (1998), segundo o qual a proximidade geográfica seria o único fator confiável para se prever a similaridade entre áreas. Na Figura 2, observa-se a definição de um grupo formado pelas matas 1, 2, 3 e 4 (matas de Pernambuco) e outros sete grupos formados por matas isoladas.…”

Are the ancient forests of the Eastern Po Plain large enough for a long term conservation of herbaceous nemoral species?

“…Species such as forest floor species of ancient forests (''ancient forest species'', sensu Hermy 1994), suffer increased extinction probability because of plant traits linked to their biological and ecological features. These characteristics ensue from adaptation to stable environment, supporting species with slow growth, stress tolerant strategy, early and short flowering, vegetative propagation, heavy seeds and transient seed bank (Davies et al 2000;Jacquemyn et al 2001;Verheyen et al 2003). The local extinction of ancient forest species further increases for their limited dispersal power in space, which in turn leads to low recolonization ability from adjacent fragments Matlack 2005) making the so-called ''rescue effect'' impossible (Piessens et al 2005).…”

“…Date differs between countries and studies and it is selected on the availability of information: e.g. Peterken (1974) suggested 1600 for Great Britain, Jacquemyn et al (2001) 1770-1800 for Belgium, Lawesson et al (1998) 1789 for Denmark, GrashofBokdam & Geertsema (1998) 1850 for Netherlands. The concept of ancient forests differs from that of old-growth forests.…”