From a biological perspective, a military installation is not an island, existing in isolation. It lives within a larger landscape comprising both natural and anthropogenic systems. A natural landscape can be thought of as the spatial scale at which ecosystems reoccur (Forman 1995). Meta-populations often function at this scale, with sub-populations occurring in ecosystem patches scattered throughout the landscape. Many wide-ranging species are very sensitive to the landscape pattern.
These species often use, and require, two or more ecosystems for survival. These ecosystems may often not be congruent, and the species must travel through the landscape. Smaller installations may encompass only a small portion of the landscape mosaic and, as a result, critical habitats and ecosystems may only occur off-site. In these circumstances, it is very important to look beyond the installation’s boundaries.
Alternatively, a large military installation can often be fruitfully managed as a landscape unto itself—or sometimes as a microcosm of a much larger landscape. Natural buffer zones, impact areas, training areas, and other developed lands together join to form a landscape mosaic. There is great opportunity to build upon this existing mosaic, creating missing patches or systems, and enhancing others to affect significant conservation results.
It is at this scale that concerns about variety, variability, multiple biological levels, and sustaining processes come to the fore.
Regardless of size, the encroachment on an installation’s boundaries presents challenges to achieving both the military and the biodiversity conservation missions. The conversion of lands within the installation’s natural landscape has consequences to the biodiversity on-site by fragmenting and isolating subpopulations of key species and changing the patch structure driving important natural communities out of their natural range of variation (NRV). Encroachment also increases the likelihood of unnatural disturbance, changes the disturbance regimes important to ecosystem function, and can be a source of invasive species.
Next Page: Ecoregions
Bob Unnasch, Ph.D.
Sound Science LLC