Spatial Patterns And Influence Factors Of Ant Species Richness And Functional Richness

The research of biodiversity spatial patterns is a research hotspot in macroecology and biogeography. Ant is an ideal organism for spatial patterns studies due to its important ecological functions, high level biodiversity, and wide distributions. Studying the ant distribution patterns is beneficial to exploring the causes of biodiversity spatial patterns, environmental conservation and monitoring environmental changes.Ant communities in different stratum were investigated by pitfall traps, Winkler extraction, and arboreal ants bait trap in seven typical land-use types(secondary natural forest, eucalyptus plantation, rubber plantation, lac plantation, dry land, paddy field, and lac agroforestry) in Luchun County, Yunnan Province in October 2012 and April 2013. This research compared spatial patterns of ant abundance, species richness, rare species number, and functional richness in different stratum and in different land-use types. Then, we discussed various impact factors of them, and the relationships between species richness and functional richness. The major results were as follows:(1) 37891 individuals belonging separately to 137 species, 52 genera, and 7 subfamilies of total ants were collected; 16704 individuals belonging separately to 106 species, 44 genera, and 7 subfamilies of ground-dwelling ants were collected; 3189 individuals belonging separately to 87 species, 41 genera, and 5 subfamilies of leaf-litter ants were collected; 17998 individuals belonging separately to 68 species, 29 genera, and 5 subfamilies of arboreal ants were collected.(2) Spatial patterns of ant abundance, species richness, rare species number, and functional richness in different stratum among different land-use type were different. On the whole, indices of ants in forest and agroforestry were higher than those in dry land and paddy field.(3) A handful of indices of elevation gradients detected peaks in abundance, species richness, rare species number, and functional richness at mid-elevations(R2=0.695~0.942,P <0.01). However, species richness of leaf-litter ants decreased with the increase of elevation(R2=0.830, P<0.01); rare species number of ground-dwelling ants increased with the increase of elevation(R2=0.847, P <0.01).(4) The abundance, species richness, rare species number, and functional richness increased with the increase of available resources(stone percentage, tree species richness, herb species richness, leaf-litter index), in certain extent. There were negative relationships between ant parameters(abundance, rare species number, and functional richness) and habitat complexity(clearing percentage and plant cover degree). The available resources and habitat complexity were important influence factors in these spatial patterns.(5) There were positive relationships between rare species number and species richness(Spearman r=0.680, P<0.01), functional richness and species richness(Spearman r1=0.736, P<0.01; Spearman r2=0.670, P<0.01). In addition, the positive relationships also existed between rare species number and functional richness(Spearman r1=0.528~0.711, P<0.01; Spearman r2=0.528, P<0.05). The change in functional richness along the environment gradient was primarily driven by rare species that are functionally unique. The level of functional redundancy was low in local ecosystem.Our results suggested that reserving appropriate leaf litter and plants in plantations is beneficial to the conservation of biological diversity and maintenance of normal ecosystem function. The low functional redundancy among species in our study indicated that species loss due to human alteration of the environment will lead to a severe decline in ecological functions.