|Wiens, J. - THE NATURE CONSERVANCY|
Submitted to: Ecography
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 13, 2000
Publication Date: December 1, 2001
Citation: BESTELMEYER, B.T., WIENS, J.A. LOCAL AND REGIONAL-SCALE RESPONSES OF ANT DIVERSITY TO A SEMIARID BIOME TRANSITION. ECOGRAPHY. 2001. V. 24(4). P. 381-392. Interpretive Summary: We asked whether large scale shifts in vegetation correspond to shifts in distributions of ant faunas. We focused on ants because they are important animals in semiarid grasslands due to their diversity and use as bioindicators of ecosystem health. Understanding whether animal and vegetation distributions match is important because conservation planners often use vegetation distribution as a surrogate for animal distribution. We found such a concordance existed at small scales (such as transition from grassland to shrubland) only in desert grasslands but not in shortgrass steppe. We found that large-scale changes in vegetation (the shift from blue to black grama grass dominance in central New Mexico) did not match shifts in kinds of ants observed in these areas. This means that vegetation patterns (for example, from maps or remote sensed data) can be used to predict ant patterns in ant communities only in certain situations. .From a practical standpoint, this indicates conservation planning in grasslands will require more detailed surveys of ants, and probably other taxa, that are currently available.
Technical Abstract: The locations of biome transitions and ecotones are frequently defined by the rapid shift from one form of dominant vegetation to another. The composition of animal taxa is predicted to shift parallel with that of dominant plants, and species diversity is predicted to be greater in transitional zones than in adjacent areas. We asked whether ant species diversity and composition supported these predictions across a biome transition between shortgrass steppe and Chihuahuan Desert vegetation. Neither species richness nor diversity was highest at the biome transition region as a whole or within habitats in the biome transition. The biome transition region was not intermediate in ant species composition or in the representation of different faunal complexes. The community similarity between matched habitats shared between the biome transition zone and adjacent regions was less than that between distinct habitats occurring within regions. A zoogeographic transition for ants may occur to the nort of the phytogeographic transition and may be coincident with the northern limits of monsoonal precipitation patterns. In contrast, the phytogeographic transition may be related to less extreme climatic variation within the monsoonal region occurring further south.