3.1 Conservation Goals and Criteria
Sep 19th, 2007 by leb3
In the Landscape Measures framework, the term ‘conservation’ encompasses two closely linked environmental assets: wild biodiversity and ecosystem services.
Wild, or native biodiversity has a spatial component. Genes, populations, species, and ecosystems form naturally occurring patterns that often can be differentiated from the patterns that humans bring about through large-scale changes such as intensive agriculture and the introduction of invasive species. From a conservation standpoint genes, populations, species, and ecosystems generally are considered desirable when they occur in their naturally occurring patterns and undesirable when they occur elsewhere, as is the case with exotic species.
The discussion of natural pattern, of course, begs the question of what “natural” means, given that communities are always in flux due to the processes of evolution, climate change, and other influences. This is a challenging issue that has been much debated. In general, though, a consensus holds that the pace and magnitude of changes to ecological communities is qualitatively different under modern human management regimes than under pre-modern regimes. In many landscapes, therefore, it is reasonable to define the reference condition for wild biodiversity as the condition of ecological communities prior to the advent of modern land use practices that removed or transformed natural ecosystems on a large scale, such as intensive agriculture and urbanization.
Ecological communities that approximate this reference condition still exist in many agricultural landscape mosaics such as parks, wildlife refuges, or nature reserves. Where they do not, reference conditions may be inferred by historical records and remnant fragments. However, in some places, such as western Europe, ecosystems have been shaped by such intensive and long-lasting human use that it may not be possible or useful to define the reference condition in terms of naturally occurring patterns of biodiversity. In such places, the goals for biodiversity conservation must be informed by cultural values, but can be heavily guided by scientific analysis.
Ecosystem services—the second part of the conservation goal—are ecological processes and functions that sustain and improve human life (Daily 1997). Ecosystem services play a central role in multi-functional landscapes, and are a key tenet of the LM approach, creating the link and inter-relationship between conservation, production, and livelihoods as illustrated here.
Although wild biodiversity and ecosystem services are closely linked, they are not synonymous. A landscape with relatively intact wild biodiversity is likely to provide a full complement of ecosystem services. However, there is evidence that many ecosystem services can also be provided by non-native species, or by combinations of native and non-native species in heavily managed settings such as permanent farms. The implication is that even where wild biodiversity has been significantly reduced to make way for food and fiber production, high levels of ecosystem services often can still be provided through intentional land management practices.
On the other hand, managing an ecoagriculture landscape for ecosystem services does not ensure that wild biodiversity will be adequately protected. Thus, wild biodiversity and ecosystem services both require explicit consideration in multifunctional agricultural mosaics.
The following goal and criteria are consistent with this thinking.
Conservation Goal: The landscape conserves, maintains, and restores native biodiversity and ecosystem services
Criterion C1: The landscape contains an adequate quantity and suitable configuration of natural and semi-natural habitat to protect native biodiversity.
Simply put, a “habitat” is where a plant or animal lives. A natural habitat is one that contains native species and has proceeded along some ecological path of development. It does not need to be “old” to be natural. For viable populations of plants or animals to exist, there needs to be some minimum amount of land cover that constitutes the habitat; the spatial distribution and configuration of this land cover (i.e., its pattern) over the landscape is also important. Most biodiversity does not need pristine habitat to exist, although some may, so a combination of natural and somewhat disturbed (i.e., semi-natural) habitats are worth protecting.
Criterion C2: Natural and semi-natural habitats within the landscape approximate the composition and structure of the habitats historically found in the landscape.
Following Angermeier and Karr (1994), ecological integrity denotes a system with its historical species composition and structure. This is the definition then used by Callicott and Mumford (1997). Composition refers to the assemblages of species in those habitats, and structure refers primarily to physical attributes of the habitat such as multi-layering of forests, decomposing logs on the ground, pit and mound topography, etc.
Criterion C3: Important species within the landscape are biologically viable.
Certain species within the landscape may be deemed to be biologically, economically, or politically “important”. Biological viability is synonymous with population viability, which has demographic and genetic components.
Criterion C4: The landscape provides locally, regionally, and globally important ecosystem services.
An ecosystem that provides ecosystem services, or at least a substantial proportion of all possible ecosystem services, is healthy. This concept is integrally related with that of function, and with ecological health as defined by Callicott and Mumford (1997). An ecosystem is healthy if it still provides primary production, nutrient retention and cycling, nitrogen fixing, soil stabilizing, water purification, and other processes.
Criterion C5: Natural areas and aquatic resources are not degraded by productive areas and activities.
Productive agricultural areas have a tendency to leak soil, chemicals, weedy plants, and foraging livestock into nearby non-farmed areas and waterways.
Continue to Unit 4: Choosing Indicators