Chapter 2: Remote Sensing Mapping and Research
Mine Area The total amount of mine area changed from 1.10 km2 in 1998 to 15.73 km2 in 2005 (Table 9): a 13-fold increase. We documented an average annual change of approximately 2 km2 over the time period examined. The total mine area mapped over the Health study area (BMAs 3 and 4) was 15.73 km2 in 2005. Table 9: Mine area and change in mine area from 1998 to 2005. Please note that estimates from 1998 to 2001 were derived from the North Health study area, while those from 2002 to 2005 were derived from the North and South Health study areas combined. Year 1998 1999 2000 2001 2002 2003 2004 2005
Area (km2) 1.10 1.10 3.50 6.58 10.64 12.20 14.26 15.73
∆ Area (km2) 0.00 2.40 3.08 4.06 1.56 2.06 1.47
Changes in Landscape Structure 1998-2005: Local Scale As expected, landscape structure and conditions displayed significant spatial variability across the study area, both in terms of their mean annual amounts of change (Table 10) and structural trajectories over time (Figure 12). The mean annual area of forest change varied from 38.5 hectares distributed across 3.2 new patches per year in Area 1 to 322.3 hectares distributed across 21.3 new patches per year in area 3. Annual trends over time revealed consistent increases in edge density and decreases in mean patch size. Despite the wide range of cumulative loss of forested areas, the selected landscape metrics appear fully capable of tracking logically-consistent patterns of landscape structure over time, efficiently revealing the changing patterns of land cover associated with increasing human activities. Table 10: Temporal occurrence and mean annual amounts of forest change patches across the three selected 13 x 13 km case study areas, reflecting low, moderate and high levels of change. Occurrence of Annual Forest Change Patches Case Study Area
Number of Years (n)
1 – Low Change
4
2 – Mod. Change 3 – High Change
7 7
Time Frame (Years) 1998-2000; 2001-2003 1998-2005 1998-2005
43
Annual Amount of Forest Change Patches Mean Annual Mean Number of Area of Change Change Patches (ha) (n) 38.5
3.2
252.5 322.3
10.6 21.3