Congruence across taxa and spatial scales: Are we asking too much of species data?

Abstract

Aim Biodiversity monitoring and conservation are extremely complex, and surrogate taxa may represent proxies to test methods and solutions. However, cross‐taxon correlations in species diversity (i.e., cross‐taxon congruence) may vary widely with spatial scale. Our goal is to assess how cross‐taxon congruence varies with spatial scale in European temperate forests. We expect that congruence in species diversity increases when shifting from fine to coarse spatial scales, with differences between species richness and composition, and across pairs of taxonomic groups. Location European temperate forests. Time period Present. Major taxa studied Vascular plants, bryophytes, birds, epiphytic lichens, saproxylic beetles and wood‐inhabiting fungi. Methods We used field data (354 plots across 23 sites) encompassing Italy, France and Hungary, with species information for six taxonomic groups. We accounted separately for spatial grain (the size of elementary sampling unit) and extent (the geographical area included in the survey) and evaluated the relationships within all the possible pairs of taxa. Results Although no pair of taxa had its species richness consistently correlated across scales, we found no changes in the direction of correlations when analysing species composition. However, when increasing grain and extent, we did find a general increase in the magnitude of correlations in species composition and partial changes in significance, with plants having the highest number of significant correlations. Main conclusions Species richness congruence among taxa is strongly scale dependent owing to differences in the relative contribution of large‐ and small‐scale processes across taxa. Cross‐taxon congruence in species composition is scale dependent only for its magnitude, because life‐history traits of individual species make responses to environmental factors similar across scales. Forest monitoring should consider multi‐taxon sampling and limit the use of surrogates at specific spatial scales, especially for species richness. Sampling plant species composition in scattered plots across different sites may effectively summarize the whole community composition.

Cross‐taxon congruence of multiple diversity facets of freshwater assemblages is determined by large‐scale processes across China

“…Consideration to multiple scales is therefore necessary for disentangling difference in the relative contribution of large and small-scale processes across taxa (Burrascano et al, 2018). Lastly, we used different environmental variables as proxies for testing different plausible driving mechanisms for the observed cross-taxon congruence patterns.…”

“…However, energy and environmentally-related factors still can play an important role in driving patterns of diversity at broad geographic scales (Hawkins et al, 2003). microclimatic conditions, occurrence of specific elements), the inclusion of a wider extent and, consequentially, broader ecological gradients, increased congruence for all pairs of taxa (Burrascano et al, 2018). A recent study on forest communities found that when compared with the effect of fine-scale determinants directly or indirectly related to forest structure (e.g.…”

“…A recent study on forest communities found that when compared with the effect of fine-scale determinants directly or indirectly related to forest structure (e.g. microclimatic conditions, occurrence of specific elements), the inclusion of a wider extent and, consequentially, broader ecological gradients, increased congruence for all pairs of taxa (Burrascano et al, 2018). Thus, the congruence we observed suggests that fish diversity may be predicted by aquatic plant diversity at broad scales, but the local ecological preferences of the species should also be assessed to preserve their habitats and ecological interactions between macrophytes and fish.…”

Trade‐offs between carbon stocks and biodiversity in European temperate forests

“…Multi‐taxonomic data were collected in six different projects (Burrascano et al, ) using comparable, but not identical sampling protocols (Supporting Information Table S3 for details). All vascular plant species were recorded in plots ranging from 314 to 1,256 m 2 .…”

Exploring patterns of beta‐diversity to test the consistency of biogeographical boundaries: A case study across forest plant communities of Italy

“…In contrast, dynamics in more impacted habitats (e.g., in agroecosystems) or dynamics of mobile organisms (e.g., spore dispersing fungi) could be less sensitive to biogeographical processes being more prone to homogenization (Winter et al, ). This claims for further large scale, multi‐habitat, and multi‐taxon studies and for a habitat and taxon‐specific approach to conservation (Burrascano et al, ; Flensted et al, ; Nascimbene et al, ). According to these findings, EU conservation policies should distinguish between habitat and taxa that are manageable according to a biogeographical approach (McIntosh & Burbidge, ) and those that are more influenced by local processes.…”