Dispersion of kangaroo rat mounds at multiple scales in New Mexico, USA

Burrowing mammals create disturbances that increase the ecological heteroge neity of landscapes. In desert systems, banner-tailed kangaroo rats (Dipodo mys spectabilis) construct large mounds that greatly influence the spatial patterning of soils, plants, and animals. The overall effects of the patche s generated by D. spectabilis depend on the dispersion patterns of the moun ds; these patterns may be sensitive to scale and landscape position. We exa mined the distribution of D. spectabilis mounds across multiple scales in f our 40-ha grassland plots in New Mexico, USA. We used Ripley's K-function f or our point-pattern analysis. The dispersion patterns of mounds were gener ally scale-sensitive but depended somewhat on plot-level densities, which w ere related to topographic position and grazing history. Mound spacing was either regular or random at small scales (0-50 m), random or aggregated at intermediate scales (50-300 m), and aggregated at large scales (300-3000 m) . This scale-dependency of pattern reflected spatial domains in which diffe rent biotic (territoriality, dispersal, grazing) and abiotic (soil texture and drainage) factors exerted strong influences. How other organisms percei ve the spatial patterning of mounds will depend on the extent of their move ments. Patches may appear regular to one species but aggregated to another. The dispersion of D. spectabilis mounds also has implications for the spat ial structuring of desert rodent communities. D. spectabilis excludes small er species of kangaroo rats from areas around their mounds; they create spa tial heterogeneity in behavioral dominance that may influence the distribut ion of subordinate species at multiple scales.