How To Prioritize Sites: Step 7

Step 7: Apply empirical generalizations to guide planning when data are deficient

Conservation planners never have enough data to make fully informed decisions, and sometimes a planning region is so poorly surveyed that virtually no ground-level data exist. Depending on the availability and quality of data, empirical generalizations derived from case studies elsewhere can be used with care and caution to guide conservation planning.

These generalizations (adapted from Noss 2007 and elsewhere) include:

  • Nature is full of surprises. Ecosystems are dynamic, not static, and often display non-linear dynamics with unpredictable outcomes. Planners should be aware that the land conservation system they are designing may not function the way they thought it would. Plans should account for and allocate substantial financial and technical support for monitoring and adaptive management, which must often include changes in land-use plans over time.
  • The fewer the available data or the greater the uncertainty about plan outcomes, the more conservative a plan should be. This is a risk-averse or precautionary strategy—be willing to err on the side of protecting too much land rather than too little, where possible.
  • Large conservation areas are better than small areas. This does not mean that one large area is better than several smaller areas—the answer to that question will vary case by case.
  • More conservation areas spread across the planning landscape are better than fewer areas. This ensures that the conservation network captures beta diversity – the turnover in species composition among sites – and will help avoid “contagious catastrophes” and synchronistic population dynamics that could bring multiple populations of a species to extinction at once.
  • Connectivity is better than disconnectedness. Goals should seek to maintain or restore natural connections across the planning region, either through corridors or through permeability of the landscape matrix, rather than creating artificial corridors such as roadsides. Connectivity is very species-specific and landscape-specific. In the absence of detailed information, a general rule is to maintain, restore, or mimic the connectivity of the natural landscape (but focusing on movement needs and behaviors of the species most sensitive to fragmentation).
  • Unfragmented habitat is better than fragmented habitat. This refers to human-made habitat fragmentation—by roads, developments, etc.—not to the heterogeneity or patchiness inherent to natural landscapes.
  • Roads are generally bad for native biodiversity. Few if any landscape features have more consistently negative ecological impacts than roads. Because human-inhabited landscapes almost always contain roads, additional research is required to understand wildlife-road interactions and to develop functional wildlife crossings, hydrological connectivity, and other mitigation measures. In the absence of good information, minimize road density to the extent practicable.
  • Balance complementarity and redundancy. For example, more than one example of every ecosystem type and more than one population of every species are needed to improve chances of persistence.
  • A diverse conservation strategy spreads the risk of failure of any one approach. Rather than relying entirely on focal species, incorporate special elements and ecosystem representation into planning.
  • Maintain ecological processes and habitat/landscape structure within a natural (historic) range of variability. Such an approach provides for resilience and ecosystem integrity.

Steps 8-10

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