Monday, August 3, 2009 - 3:40 PM

COS 16-7: CANCELLED - Mammals and landscape habitat along a gradient of matrix development intensity

Megan J. Brady, The University of Queensland


The matrix is an important element of landscape mosaics.  It has a pervasive influence on habitat and alters an animal’s ability to move through and persist in a landscape.  However, the matrix is not uniform in its impacts, but the type and intensity of land use in the matrix shape its impacts.  Furthermore, other attributes of modified landscapes such as habitat loss and fragmentation can often confound the effects of the matrix.   To isolate matrix effects, I identified 19, 500m radius landscapes in southeast Queensland, Australia, with similar remnant forest patch attributes, habitat loss, and fragmentation, but exhibiting a marked gradient from rural through high-density suburban development of the matrix.  I quantified intensity of matrix development using a novel weighted road-length metric, based on a roads ecological influence, which was also highly correlated with housing density.   In each landscape I surveyed mammals and disturbance and habitat attributes in patch ‘core’, patch ‘edge’ and ‘matrix’ landscape elements.  I asked two questions: (1) how does matrix development intensity impact mammal community structure, and individual mammal abundance and distribution throughout landscapes, and; (2) how do mammals respond to similarity of patch and matrix elements in habitat structure and floristics, despite matrix development intensity?  


Mammal response to matrix development intensity was highly species specific.  Several native species rapidly declined in abundance, however, others were more robust to moderate levels of matrix intensity.  Species response to matrix development intensity appeared to be related to their abundance in edge or matrix sites.  Native species richness peaked at moderate levels of matrix development intensity.  Exotic species richness, feral predators and human disturbance increased with matrix intensity.  Ordination analyses showed landscape elements were more similar in habitat structure and floristics, which may suggest enhanced landscape habitat quality, at low to moderate levels of matrix intensity.  However, there was no significant relationship between native species richness and similarity of core and matrix elements, although exotics and predators increased with dissimilarity of core and matrix.  Results suggest that many native species can be resilient to landscape modification, however, disturbance factors emanating from the matrix may be preventing wildlife from using otherwise suitable habitat across the landscape, even when both patch and matrix is of high habitat quality.