Data from: Isolated trees support lower bird taxonomic richness than trees within habitat patches but similar functional diversity

Large isolated trees are keystone structures that can help maintain
biodiversity in fragmented landscapes, with evidence that open areas with
isolated trees may support similar levels of taxonomic diversity to nearby
patches of habitat. However, it is not clear if isolated trees can support
the same diversity of ecological functions as trees in habitat patches. We
compared species richness, community composition and functional diversity
of birds in trees at forest edges and isolated trees. Twenty isolated
trees and ten edge trees of American muskwood (Guarea guidonia) were
selected, and sampled on 11 occasions, each of 20 minutes, over four
months. All individual birds that landed at trees were recorded using a
standardized protocol. Species richness was, on average, almost twice as
high at edge trees than at isolated trees. Taxonomic composition differed
between edge and isolated trees, with many forest-dependent birds
restricted to edge trees, and some open-area birds restricted to isolated
trees. Overall functional diversity was similar at edge and isolated
trees, but some ecological functions (e.g. frugivory) were less frequent,
while others (e.g. granivory) were more frequent at isolated compared to
edge trees. Isolated trees are important for supporting many ecological
functions in modified areas. However, the maintenance of forest patches is
essential to complement the provision of such functions in modified
landscapes.