Relación de número de cerdos con la capacidad funcional del sistema

The largest reductions in LCI score between 1947 and 1985 were associated with timber harvesting, and since that time timber harvesting was also associated with the greatest reductions in LCI score in western areas. Between 1985 and 2009 in the eastern areas conversion of forests to plantations following harvest as well as harvesting contributed substantially to LCI score reductions (Figure 2–5).

In 1947 settled areas in the east of the region had much lower LCI scores than western areas which had been subjected only to wildfires (Figure 2-4). By that time, the area logged was already more than twice that of deforestation. After 1947 logging caused greater reductions in LCI score then either wildfire or deforestation in the region as a whole because it affected a much greater area (Figure 2-7). Land clearance for agriculture after 1947 was minor and limited to private land in the east that had usually already been logged and/or burnt. Plantations were at least partially located in areas previously cleared or logged, mitigating their contribution to reduced LCI scores. Nevertheless, they still contributed substantially to reductions in LCI score in eastern areas, particularly after 1996. After 1947, only one landscape-scale fire was mapped in the study area (Figure 2-7), but much of the area affected by this event had either been logged just prior to it, or was subsequently salvage logged in the following decade, confounding the effect of these different disturbance types.

Logging has been a major facilitator of deforestation in places like the Brazilian Amazon and New Guinea (Broadbent et al. 2008; Shearman et al. 2012). Kostoglou (1996) noted that, within the present study area, the establishment of saw-mills (to supply global timber markets in the nineteenth century) created nodes around which unplanned townships grew and agricultural development advanced. In contrast, a number of government surveyed townships failed to establish where no sawmills were developed. Logging offset or reduced the cost of converting forest for agriculture, but was certainly by no means a pre-requisite for deforestation. Critically in Tasmania, the gazetting of forest areas as State Forest land, was important in limiting the extent to which forests were cleared in Tasmania.

Chapter 2 – Landscape context variation

Due to the lack of available mapping and survey data the present study was not able to document pre-settlement to early settlement phases in the landscape evolution of the region. But for the period covered, unsurprisingly, there was a spatial advance of logging disturbance along transport networks from settled edges into forest

landscapes, leading to major changes in LC well in advance of deforestation (Figure 2-7). This advance was by no means linear or uniform. It is evident that, from 1975, clear-felling operations leap-frogged substantial forest areas to harvest areas at the remote ends of road penetration before progressing back toward the settled regions. Clear-fell silvicultural systems adopting this harvesting pattern (also known as staggered-setting or checker-board) are common around the globe (Franklin and Forman 1987). This strategy may have occurred in earlier times, but, as all accessible and commercially valuable forest had been harvested by 1950 (Forestry Annual Report 1950/51), and the year of logging only mapped for clear-fell operations after 1963, it is not possible to provide supporting evidence. This harvesting method and pattern enabled the most valuable forests to be accessed, successfully regenerated and for the slash to be disposed of (Franklin and Forman 1987). Whether intentionally or not, it reduced remoteness of large areas of the forest estate, which in the social

context of growing global pressure to conserve old growthandwilderness, reduced its

value for reservation. Certainly, in recent negotiations towards a forest peace deal, environmentalists preferentially sought reserves in areas remaining unaffected by previous logging. Government provision of road infrastructure explicitly for timber harvesting purposes, made this leap-frog approach to harvesting economically feasible for industry. Whatever the motive, the effect of discontinuous harvesting did serve to reduce the concentration of logging from 1975. Prior to this time, harvesting,

especially salvage-logging, occurred in aggregated areas contributing substantially to the larger reductions in LCI score observed between 1947 and 1985 in harvest areas (Figure 2-5).

In the nineteenth century timber harvesting was impeded in its expansion and characteristics largely by economics and technology. More recently industrial practices have altered in response to government regulation and market pressure to reduce the environmental impacts of harvesting. While a more detailed analysis is warranted, the data show government regulations from 1985 did result in logging

Chapter 2 – Landscape context variation

coupes becoming smaller and more dispersed. In western areas where plantations where timber production was not intensified by clearance for plantations, this policy also resulted in mean LCI scores being higher in coupes following harvest in the decades following the introduction of the FPC. Ecological theory (Baker et al. 2013b) suggests that the consequence of these policy changes at least in the western areas of the study area is likely to have been a reduced impact on biodiversity from logging at the harvest site compared to the impacts of earlier harvesting practices.

The shorter distances to coupe edges were associated with smaller reductions in mean LCI score for small coupes after harvesting compared with the longer distances to coupe edges in large coupes. Although the LCI metric was capable of demonstrating that modifying coupe size led to differences in LCI score following harvest, LCI scores following harvest were actually more sensitive to the stability score of the vegetation surrounding coupes and pre-harvest vegetation. Coupes in areas previously logged, or adjacent to plantations, farmland or early seral-stage forest, have lower LCI scores prior to logging and therefore harvesting resulted in smaller reductions in LCI score compared to harvesting in areas surrounded by mature forest. Therefore, in addition to changes in coupe size and configuration, historical declines in LCI were at least partially responsible for some of the observed reductions in the magnitude of LCI change after government regulation. Nevertheless, higher mean LCI scores for coupes after logging post FPC compared with pre-FPC (Table 2–3), particularly in western areas, and for scenario one modelling (in which vegetation differences were excluded) provided evidence that regulations were responsible for reducing declines in LCI score due to harvesting.