A framework for conservation based on primary productivity and habitat heterogeneity

Background/Question/Methods

While ecologists recognize that ecosystems differ geographically, we have not provided land managers with adequate guidance on which conservation threats may be most prominent in their particular type of ecosystem.  In reviewing the historical roots from which conservation biology has grown, I found that one property, primary productivity, was once widely recognized as important but has received little emphasis since. Meanwhile, more basic studies have revealed that primary productivity can exert strong influence on individual organisms, populations, and communities and mediate the effects of landscape processes.  The goals of this paper are to: 1) develop a framework to group ecological systems based on gross primary productivity (GPP) and other factors that provides a basis for anticipating conservation priorities; and 2) summarize management strategies expected to be most effective in these different kinds of ecosystems.  I first evaluated the evidence from the literature for each of several hypotheses on how GPP may influence the attributes of ecosystems that are pertinent to conservation.  Those hypotheses that were adequately supported were used as the basis to group ecosystems based on GPP and other key factors.  Conservation priorities and biological management strategies for each group of ecosystems were then derived consistent with current principles in conservation biology.

Results/Conclusions

The resulting framework groups terrestrial ecosystems based on three levels of GPP (low, medium, and high) and two levels of habitat heterogeneity (low vs high geomorphic complexity and seral stage diversity).  The general traits of each group of ecosystem were characterized in terms of: organism body size, home range size, migration behavior; population size and growth rate; community diversity and trophic interactions; and landscape structure, composition, and land use.  The groups of ecosystems were mapped globally based on MODIS average annual GPP and topographic complexity.  I conclude that the overarching conservation priority in low-GPP systems is to maintain large, well connected natural landscapes that include the full gradient of biophysical conditions and provide for wildland species with large area requirements.  In medium GPP systems, the priority is to mitigate the heavy human influence, which has the potential to degrade these continental to global hotspots for biodiversity.  In high GPP systems, the priority is to manage soils, disturbance, and vegetation pattern to maintain the large number of microhabitat specialists and high potential species richness in these systems.  Specific management strategies among these levels of GPP should vary with habitat heterogeneity.