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Zoë Rosanagh Slattery

Fragmented Forests: Spatial Analysis of the Drivers, Characteristics and Effects of Forest Fragmentation

Building on existing literature, this study aims to answer the questions of whether specific drivers of forest fragmentation cause particular fragmentation characteristics, and how these characteristics can be linked to their effects on forest-dwelling species. 

This research uses remote imaging from NASA’s Landsat global satellite program to examine the changing patterns of forests. It focuses on areas which have undergone a high level of a specific fragmentation driver, in particular either agricultural expansion or commodity-driven deforestation. Seven municipalities in the states of Rondônia and Mato Grosso in Brazil are selected as case study areas. Land cover maps of each municipality are created using the Geographical Information System software ‘ArcGIS’ Spatial Analyst extension. The resulting categorical maps are input into ‘Fragstats fragmentation software to calculate quantifiable fragmentation metrics for each municipality. These fragmentation metrics can be grouped by the fields of area, edge, core area, shape complexity, aggregation, and contrast of forest patches within each municipality. In municipalities which experienced the same fragmentation driver, correlation between changes in fragmentation characteristics is examined. To determine the effects that these characteristics are likely to cause, this study uses a literature review to determine how species traits affect their responses to forest fragmentation. Certain traits such as size and habitat specialisation can be used to predict a species’ vulnerability to the loss of habitat and changing conditions caused by forest fragmentation.  

Results indicate that, in areas that underwent agricultural expansion, the remaining forest patches became more complex in shape with longer edges and lost a large amount of core area.  This negatively affects species which are either highly dispersive or specialist to core forest habitat. In areas that underwent commodity-driven deforestation, it was more likely that forest patches would become less aggregated and create disjunct core areas. This negatively affects smaller, sedentary animals which do not naturally travel long distances. This information will prove useful for forest managers, particularly in the case study municipalities examined in this thesis, in deciding which species require further protection measures. Further research is needed to validate whether the fragmentation characteristics change similarly for the specific drivers studied here in other locations, and for other drivers such as forest fires.