Landscape disturbance causes small-scale functional homogenization, but limited taxonomic homogenization, in plant communities

Abstract

Summary1. Biotic homogenization (BH), a dominant process shaping the response of natural communities to human disturbance, reflects both the expansion of exotic species at large scales and other mechanisms that often operate at smaller scales. 2. Here, we examined the relationship between BH in plant communities and spatio-temporal landscape disturbance (habitat fragmentation and surrounding habitat conversion) at a local scale (1 km 2 ), using data from a standardized monitoring programme in France. We quantified BH using both a spatial partitioning of taxonomic diversity and the average habitat specialization of communities, which informs on functional BH. 3. We observed a positive relationship between local taxonomic diversity and landscape fragmentation or instability. This increase in local taxonomic diversity was, however, paralleled by a decrease in average community specialization in more fragmented landscapes and in more unstable landscapes around forest sites. The decrease in average community specialization suggests that landscape disturbance causes functional BH, but there was limited evidence for concurrent taxonomic BH. 4. Synthesis. Our results show that landscape disturbance is partly responsible for functional BH at small scales via the extirpation of specialist species, with possible consequences for ecosystem functioning. However, this change in community composition is not systematically associated with taxonomic BH. This has direct relevance in designing biodiversity indicators: metrics incorporating species sensitivity to disturbance (such as species specialization to habitat) appear much more reliable than taxonomic diversity for documenting the response of communities to disturbance.

Building relevant ecological indicators with basic data: Species and community specialization indices derived from atlas data

“…In particular, the replacement rate of habitat specialist species by generalists was viewed as a direct signature of a community response to large-scale habitat degradation for animals and plants Abadie et al, 2011). In fact, it is generally expected that habitat specialists will benefit from stable and undisturbed habitats whereas, generalists should respond positively to habitat variability (Colles et al, 2009).…”

“…The CSI is expected to be higher for species assemblages mostly composed of specialist species. It can then be used as an interesting ecological indicator complementary to more traditional indicators based on diversity (Filippi-Codaccioni et al, 2010;Abadie et al, 2011). Mapping the CSI can thus provide a picture of spatial variation in the specialization level of communities, which can be related to independent sources of disturbance or used as a spatial guideline to identify sites of conservation interest (Devictor et al, 2008).…”

“…From this assumption, and providing that co-occurrence data are available, a species specialization index (SSI) can be simply deduced for each given species using the identity of the species co-occurring with that species. This approach can be applied to any dataset providing that different species assemblages have been recorded in different locations (Abadie et al, 2011;Boulangeat et al, 2012). Using this approach, specialization was equated to niche breadth to test a specific hypothesis on the role played by competition (Manthey et al, 2011), or specific functional traits (Albert et al, 2010) in species distribution.…”

Structure and composition of the herbaceous shrubby stratum in two forest areas with different ages Recovery in the Upper Paraná River Floodplain

“…Segundo Abadie et al (2011Abadie et al ( , p.1137, as perturbações tendem a diminuir drasticamente populações de algumas espécies, enquanto outras podem ser beneficiadas.…”

Effect of man-made disturbances on understory plant richness of oak forests in Iran

“…Ecologists and natural resource managers demonstrate a great attention to the relationship between the habitat destruction and species diversity (Ehrlich and Wilson, 1991). Generally, human disturbances have global negative impacts on the species diversity (Abadie et al, 2011). However Sherstha et al (2013) showed that all the types of plant diversity increased up to the maximum level where forest disturbance is intermediate in Nepal, Central Himalaya.…”