Representing biodiversity: data and procedures for identifying priority areas for conservation.

Biodiversity priority areas together should represent the biodiversity of the region they are situated in. To achieve this, biodiversity has to be measured, biodiversity goals have to be set and methods for implementing those goals have to be applied. Each of these steps is discussed. Because it is impossible to measure all of biodiversity, biodiversity surrogates have to be used. Examples are taxa sub-sets, species assemblages and environmental domains. Each of these has different strengths and weaknesses, which are described and evaluated. In real-world priority setting, some combination of these is usually employed. While a desirable goal might be to sample all of biodiversity from genotypes to ecosystems, an achievable goal is to represent, at some agreed level, each of the biodiversity features chosen as surrogates. Explicit systematic procedures for implementing such a goal are described. These procedures use complementarity, a measure of the contribution each area in a region makes to the conservation goal, to estimate irreplaceability and flexibility, measures of the extent to which areas can be substituted for one another in order to take competing land uses into account. Persistence and vulnerability, which also play an important role in the priority setting process, are discussed briefly.

Data requirements and data sources for biodiversity priority area selection.

The data needed to prioritize areas for biodiversity protection are records of biodiversity features - species, species assemblages, environmental classes - for each candidate area. Prioritizing areas means comparing candidate areas, so the data used to make such comparisons should be comparable in quality and quantity. Potential sources of suitable data include museums, herbariums and natural resource management agencies. Issues of data precision, accuracy and sampling bias in data sets from such sources are discussed and methods for treating data to minimize bias are reviewed.

Persistence and vulnerability: retaining biodiversity in the landscape and in protected areas.

An objective of biodiversity conservation activities is to minimize the exposure of biodiversity features to threatening processes and to ensure, as far as possible, that biodiversity persists in the landscape. We discuss how issues of vulnerability and persistence can and should be addressed at all stages of the conservation planning and implementation process. Procedures for estimating the likelihood of persistence and for measuring degrees of vulnerability at different spatial and temporal scales using subjective assessments, rules of thumb and analytical and simulation models are reviewed. The application of information on vulnerability and persistence to conservation planning and management is discussed under the headings of natural dynamics, replication of protection, levels of representation, source and sink population structures, refuges and critical resources, reserve design, habitat fragmentation and levels of management.

Systematic conservation planning.

The realization of conservation goals requires strategies for managing whole landscapes including areas allocated to both production and protection. Reserves alone are not adequate for nature conservation but they are the cornerstone on which regional strategies are built. Reserves have two main roles. They should sample or represent the biodiversity of each region and they should separate this biodiversity from processes that threaten its persistence. Existing reserve systems throughout the world contain a biased sample of biodiversity, usually that of remote places and other areas that are unsuitable for commercial activities. A more systematic approach to locating and designing reserves has been evolving and this approach will need to be implemented if a large proportion of today's biodiversity is to exist in a future of increasing numbers of people and their demands on natural resources.

Beyond opportunism: Key principles for systematic reserve selection.

The intention and practice of conservation reserve selection are different. A major reason for systems of reserves is to sustain biological diversity. This involves protecting examples of as many natural features, e.g. species, communities or environments, as possible. In reality, however, new reserves have rarely been dedicated for their representation of features. Furthermore, the opportunism that has characterized the development of reserve systems can actually jeopardize the representation of all features in reserves through the inefficient allocation of limited resources. More systematic approaches are essential if reserves are to play their role in protecting biodiversity. Some basic principles for conservation planning are emerging from recent systematic procedures for reserve selection. These principles will help to link intention and practice.

Diversity of Eucalyptus species predicted by a multi-variable environmental gradient.

Changes in species diversity are examined in relation to a multidimensional environmental gradient using Eucalyptus species in south-eastern Australia. By fitting a generalized linear model, the response of the community parameter, species diversity, is shown to be related to three environmental variables, mean annual rainfall, mean annual temperature and a relative measure of solar radiation. The effects of rainfall and temperature were both statistically significant and large, solar radiation was significant but small. However, the influence of the two major variables was not independent but interacted in a complex way that prevents adequate description of species diversity as a function of either variable alone. Possible biological explanations of the complexity are discussed in terms of limiting conditions at low temperatures, and competition between guilds of species at high temperatures and medium to high rainfall.