Biogeographic patterns in small ground-dwelling vertebrates of the Western Australian wheatbelt

Abstract

-Cround-dwelling frogs, reptiles and small mammals were sampled at 252 quad rats chosen to represent the geographical extent and diversity of uncleared terrestrial environments across the WestE'rn Australian wheatbelt. These sitE's were not overtlv affected by secondarv salinisation, but did include sites that were 'natu~ally' saline. We recorde~i a total of 144 species from 74 genera and 15 families. There was an average of 10.4 species per quadrat with a range from one to 19. Vertebrate species richness was highest on dissection valley floors and sandy depositional surfaces of the 'old plateau' but lowest on saltflats. Total species richness was positively correlated with high levels of sand, with low levels of soil nutrients and with good soil drainage. When frogs, reptiles and mammals were considered separately, temperature and rainfall attributes were also shown to exhibit correlations with species richness. Patterns in species composition could be explained in terms of climatic and substrate variables, including salinity. Two distinct faunas were identified -one concentrated in the semi-arid northern and inland parts of the study area, and one concentrated in the more mesic south and south-east. Further patterning could be discerned within this dichotomy, including the existence of a small group of species that arc associated with saline areas. Correlations between climatic and substrate variables could be discerned even at very low levels in the classification analysis, suggesting strong deterministic patterns in vertebrate species composition across the study area. Integrated management programs over entire catchments will be necessary in order to maintain conservation values, but there is doubt that the impacts~)f salinisation and fragmentation can be mitigated quickly enough to allow the small, ground-dwelling vertebrate fauna to withstand the effects of these processes in the Western Australian wheatbelt.

Herpetological assemblages of the Pilbara biogeographic region, Western Australia: ecological associations, biogeographic patterns and conservation

“…How et al 1988;Storr et al 1999Storr et al , 2002McKenzie et al 2000b;Burbidge et al 2004;Tyler and Doughty 2009) and our previous fi eld experience in other parts of Western Australia. The use of such extrinsic information on habitat preferences and distribution provides an indication of whether the classifi cation is biologically meaningful.…”

“…These included nitrogen, phosphorus, potassium, pH, electrical conductivity, organic carbon, clay-siltsand percentages and magnesium (cf. Burbidge et al 2004). …”

“…In rocky areas, it was often necessary to drill and blast the rocky substrate to enable insertion of the pit traps. A 2-litre plastic jar was placed in the base of each pit, with a cone-shaped plastic funnel positioned in the mouth of the jar to reduce escapes, particularly climbing species such as the gecko genus Gehyra that can climb smooth vertical surfaces owing to their welldeveloped adhesive toe pads (Burbidge et al 2004;JKR, pers. obs.).…”

Frog survival and population viability in an agricultural landscape with a drying climate

“…Although H. albopunctatus currently appears widespread and secure (Burbidge, Rolfe, McKenzie, & Roberts, ; Roberts, Conroy, & Williams, ), detailed studies of genetic structuring (Davis & Roberts, ), adult survival (Davis & Roberts, ), larval survival (Davis, 2004) and egg survival (Davis & Roberts, ) indicate the presence of small, subdivided populations, evidence of high larval mortality and instances of no or very low recruitment. This is counterbalanced by a small number of populations with positive demographic features, which may indicate the possibility of a source–sink metapopulation structure (Harrison, ).…”

“…We aimed to predict the likely persistence of this species in a highly modified landscape that still presents opportunities for successful persistence. H. albopunctatus occurs across all of its known range (Burbidge et al, ) and uses a wide range of water bodies for breeding that have been generated by human modification of the landscape (Davis, 2004).…”