Modelling land use and land cover change in the Strzelecki ranges

Modelling land use and land cover change in the Strzelecki ranges

Land use and land cover change (LUCC) has been recognized as an important driver of environmental change on all spatial and temporal scales (Turner et al., 1994). LUCC contributes significantly to earth atmosphere interactions, forest fragmentation, and biodiversity loss. It has become one of the major issues for environmental change monitoring and natural resource management. In Australia, modification of land cover since European settlement has largely been due to land clearing and weed invasion, as well as to some natural disturbances such as bushfire. In the Strzelecki Ranges, located in south eastern Victoria, the wide scale of land clearing, subsequent agricultural abandonment and fires have all resulted in severe landscape disturbance in the Ranges. Land use and land cover have undergone further significant changes with the establishment of large scale plantations in the area over the last four decades. However, details of land use and land cover change and its influence on the rainforest in this area is unknown.

The Strzelecki Ranges, along with the southern uplands of the Otways, the Central Highlands, and East Gippsland, are recognised as one of the four major Victorian areas which support cool temperate rainforest ecosystems. Cool temperate rainforest, although now very restricted in its distribution, is of major historical and ecological significance. Areas bordering cool temperate rainforest in the Eastern Strzeleckis comprise a mosaic of different land use patterns and have histories which are affected by both natural and human disturbances. Different land use patterns have different influences on imbedded remnant patches of cool temperate rainforest mainly through edge effects. When the surrounding landscape patterns change, the environmental conditions (e.g. microclimate) produced along these edges (the boundaries between surrounding forests and the cool temperate forest) may be modified and influences the interior cool temperate forest (Murcia, 1995; Bannerman, 1998).

This study aims to model the long term land use and land cover changes (from 1954 to 2004) in the Strzelecki Ranges by integrating remote sensing and geographical information system (GIS) and to provide quantitative analysis of LUCC information in the area. The reconstructed history of land use and land cover is mainly based on historical aerial photography with the support of Vicmap Elevation, Ecological Vegetation Classes (EVCs) map and stereo models established by using stereo pair of aerial photographs. Available archived historical aerial photographs, taken in 1954, 1972 and 1988, were all scanned and converted to digital format for digital photogrammetric processing. Scanned aerial photos, together with digital colour aerial photos taken in 2004 were used for classification to identify different land covers.

The results show that land use and land cover in the study area changed substantially from 1954 to 2004. Large areas of cleared land and forest regrowth on previously cleared land were gradually converted to plantations. Wet forest cover kept increasing during this period, especially from 1954 to 1988. The area covered by cool temperate rainforest has remained relatively stable throughout the period. Large scale plantation, although not equivalent to native forest as wildlife habitat, may improve environmental balances (Lamb, 1998; Loyn, 2000; Cawsey and Freudenberger, 2003; Kanowski et al., 2003; Kanowski et al., 2005; MacHunter et al., 2006; Koskela et al., 2007) and provide refuges for wet forest and surrounded cool temperate rainforest fauna, especially in areas of severe disturbance like that of our study area.