Habitat fragmentation: consequences, management and future research priorities

[Extract] Change in land use and land cover, and the associated fragmentation of habitat, is one of the most pervasive effects of human activities on the face of the globe. Habitat destruction and fragmentation are the likely primary causes of the increase in the rate of extinction over recent decades (Henle et al. 1996). All measures of habitat destruction and fragmentation in all areas on earth today indicate a severe and accelerating problem (e.g., Whitmore 1997). Even large wilderness areas like the Amazon are becoming fragmented. In the Amazon, forest clearing increased exponentially during the 1970s and 1980s (Fearnside 1987) and continues at an alarming rate. This is significant because the tropics are highly diverse and relatively unknown. In Peninsular Malaysia, for example, there are over three thousand tree species of over 30 cm diameter, compared to fifty species indigenous to continental Europe north of the Alps and west of the Urals (Whitmore 1997)

Habitat fragmentation: consequences, management and future research priorities

[Extract] Change in land use and land cover, and the associated fragmentation of habitat, is one of the most pervasive effects of human activities on the face of the globe. Habitat destruction and fragmentation are the likely primary causes of the increase in the rate of extinction over recent decades (Henle et al. 1996). All measures of habitat destruction and fragmentation in all areas on earth today indicate a severe and accelerating problem (e.g., Whitmore 1997). Even large wilderness areas like the Amazon are becoming fragmented. In the Amazon, forest clearing increased exponentially during the 1970s and 1980s (Fearnside 1987) and continues at an alarming rate. This is significant because the tropics are highly diverse and relatively unknown. In Peninsular Malaysia, for example, there are over three thousand tree species of over 30 cm diameter, compared to fifty species indigenous to continental Europe north of the Alps and west of the Urals (Whitmore 1997)

A biodiversity conservation plan for Papua New Guinea based on biodiversity trade-offs analysis

A rapid biodiversity assessment ("BioRap") project identified candidate areas for biodiversity protection in Papua New Guinea (PNG) and provides an ongoing evaluation framework for balancing biodiversity conservation and other land use needs. Achieving a biodiversity protection target with minimum opportunity cost was an important outcome given that biodiversity values overlap with forestry production values, and high forgone forestry opportunities would mean significant losses to land owners and the government. Allocation of 16.8% of PNG's land area to some form of biodiversity protection was required, in order to achieve the level of biodiversity representation/persistence that would have been possible using only 10% of the land area if there were no constraints on land allocation and no land use history. This result minimizes potential conflict with forestry production opportunities while also taking account of land use history, human population density and previous conservation assessments. The analysis provides more than a single set of proposed priority areas. It is a framework for progressively moving towards a country-wide conservation goal, while at the same time providing opportunities to alter the priority area set in light of new knowledge, changes in land use, and/or changes in economic and social conditions

Conservation targets for viable species assemblages in Canada: are percentage targets appropriate?

Percentage targets for conservation have become a popular tool (advocated in both the scientific literature and the conservation community) for setting minimum goals for the amount of land to be set aside as protected areas. However, there is little literature to support a consistent percentage target that might be widely applied. Moreover, most percentage targets have not taken into account issues of species persistence. A recent study of herbivores in Kruger National Park took into account issues of representation and persistence in setting conservation targets and found that results were consistently about 50% and were unaffected by different permutations of the reserve selection process. Here, we carry out a similar analysis for representation of mammals within sites that are predicted to allow for their persistence, across eight ecologically defined regions in Canada to test whether we see similar consistent patterns emerging. We found that percentage targets varied with the different permutations of the reserve selection algorithms, both within and between the study regions. Thus, we conclude that the use of percentage targets is not an appropriate conservation strategy

Some future prospects for systematic biodiversity planning in Papua New Guinea - and for biodiversity planning in general

We describe three challenges for biodiversity planning, which arise from a study in Papua New Guinea, but apply equally to biodiversity planning in general. These are 1) the best use of available data for providing biodiversity surrogate information, 2) the integration of representativeness and persistence goals into the area prioritization process, and 3) implications for the implementation of a conservation plan over time. Each of these problems is linked to the effective use of complementarity. Further, we find that a probabilistic framework for calculating persistence-based complementarity values over time can contribute to resolving each challenge. Probabilities allow for the exploration of a range of possible complementarity values over different planning scenarios, and provide a way to evaluate biodiversity surrogates.\ud \ud The integration of representativeness and persistence goals, via estimated probabilities of persistence, facilitates the crediting of partial protection provided by sympathetic management. For the selection of priority areas and land use allocation, partial protection may be a "given" or implied by an allocated land use. Such an integration also allows the incorporation of vulnerability/threat information at the level of attributes or areas, incorporating persistence values that may depend on reserve design. As an example of the use of persistence probabilities, we derive an alternative proposed priority area set for PNG. This is based on 1) a goal of 0.99 probability of persistence of all biodiversity surrogate attributes used in the study, 2) an assumption of a 0.10 probability of persistence in the absence of any form of formal protection, and 3) a 0.90 probability of persistence for surrogate attributes in proposed priority areas, assuming formal protection is afforded to them.\ud \ud The calculus of persistence also leads to a proposed system of environmental levies based on biodiversity complementarity values. The assigned levy for an area may change to reflect its changing complementarity value in light of changes to protection status of other areas. We also propose a number of complementarity-based options for a carbon credits framework. These address required principles of additionality and collateral benefits from biodiversity protection. A related biodiversity credits scheme, also based on complementarity, encourages investments in those areas that make greatest ongoing contributions to regional biodiversity representation and persistence. All these new methods point to a new ·systematic conservation planning" that is not focused only on selecting sets of areas but utilizes complementarity values and changes in probabilities of persistence for a range of decision making processes. The cornerstone of biodiversity planning, complementarity, no longer reflects only relative amounts of biodiversity but also relative probabilities of persistence