Assessing the overall biological diversity of tropical rain forests is a seemingly
insurmountable task for ecologists. Therefore, researchers frequently sample selected taxa that
they believe reflect general biodiversity patterns. Usually, these studies focus on the
congruence of a diversity (the number of species found per sampling unit) between taxa
rather than on b diversity (turnover of species assemblages between sampling units). Such
approaches ignore the potential role of habitat heterogeneity that, depending on the
taxonomic group considered, can greatly enhance b diversity at local and landscape scales. We
compared a and b diversity of four plant groups (trees, lianas, terrestrial herbs, epiphytic
liverworts) and eight animal groups (birds, butterflies, lower canopy ants, lower canopy
beetles, dung beetles, bees, wasps, and the parasitoids of the latter two) at 15 sites in Sulawesi,
Indonesia, that represented natural rain forest and three types of cacao agroforests differing in
management intensity. In total, we recorded 863 species. Patterns of species richness per study
site varied strongly between taxonomic groups. Only 13–17% of the variance in species
richness of one taxonomic group could be predicted from the species richness of another, and
on average 12–18% of the variance of b diversity of a given group was predicted by that in
other groups, although some taxon pairs had higher values (up to 76% for wasps and their
parasitoids). The degree of congruence of patterns of a diversity was not influenced by
sampling completeness, whereas the indicator value for b diversity improved when using a
similarity index that accounts for incomplete sampling. The indication potential of a diversity
for b diversity and vice versa was limited within taxa (7–20%) and virtually nil between them
(0–4%). We conclude that different taxa can have largely independent patterns of a diversity
and that patterns of b diversity can be more congruent. Thus, conservation plans on a
landscape scale need to put more emphasis on the high heterogeneity of agroforests and the
overarching role of b diversity shaping overall diversity patterns.
Assessing the overall biological diversity of tropical rain forests is a seeminglyinsurmountable task for ecologists. Therefore, researchers frequently sample selected taxa thatthey believe reflect general biodiversity patterns. Usually, these studies focus on thecongruence of a diversity (the number of species found per sampling unit) between taxarather than on b diversity (turnover of species assemblages between sampling units). Suchapproaches ignore the potential role of habitat heterogeneity that, depending on thetaxonomic group considered, can greatly enhance b diversity at local and landscape scales. Wecompared a and b diversity of four plant groups (trees, lianas, terrestrial herbs, epiphyticliverworts) and eight animal groups (birds, butterflies, lower canopy ants, lower canopybeetles, dung beetles, bees, wasps, and the parasitoids of the latter two) at 15 sites in Sulawesi,Indonesia, that represented natural rain forest and three types of cacao agroforests differing inmanagement intensity. In total, we recorded 863 species. Patterns of species richness per studysite varied strongly between taxonomic groups. Only 13–17% of the variance in speciesrichness of one taxonomic group could be predicted from the species richness of another, andon average 12–18% of the variance of b diversity of a given group was predicted by that inother groups, although some taxon pairs had higher values (up to 76% for wasps and theirparasitoids). The degree of congruence of patterns of a diversity was not influenced bysampling completeness, whereas the indicator value for b diversity improved when using asimilarity index that accounts for incomplete sampling. The indication potential of a diversityfor b diversity and vice versa was limited within taxa (7–20%) and virtually nil between them(0–4%). We conclude that different taxa can have largely independent patterns of a diversityand that patterns of b diversity can be more congruent. Thus, conservation plans on alandscape scale need to put more emphasis on the high heterogeneity of agroforests and theoverarching role of b diversity shaping overall diversity patterns.
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