Landscape Ecology and Ecosystems Management Thomas G

FOR-76 Landscape Ecology and Ecosystems Management Thomas G. Barnes, Extension Wildlife Specialist his publication introduces the concepts and Principles of Landscape Ecology Tprinciples of landscape ecology for managing To understand landscape ecology, we have to wildlife and other natural resources. It is intended focus on some of its important principles: land- to raise public awareness and give an overview of scape composition, structure, function, and a new philosophy and method for managing natu- change. ral resources at the landscape level. • Composition involves the genetic makeup of A landscape is a heterogenous area composed populations, identity and abundance of species of a cluster of interacting ecosystems that are re- in the ecosystem, and the different types of peated in various sizes, shapes, and spatial rela- communities present. tionships throughout the landscape. Landscapes • Structure involves the variety of habitat patches have different land forms, vegetation types, and or ecosystems and their patterns—the size and land uses. Another way of looking at a landscape arrangement of patches, stands, or ecosystems— is as a mosaic of habitat patches across which or- including the sequence of pools in a stream, ganisms move, settle, reproduce, and eventually snags and downed logs in a forest, and vertical die and return to the soil. The best way to envi- layering of vegetation. sion a landscape is to look at the land from an • Function involves climatic, geological, hydro- aerial perspective or to examine aerial photographs logical, ecological, and evolutionary processes to see how a particular piece of land fits into the such as seed dispersion or gene flow. larger picture. • Change involves the continual state of flux Landscape ecology is the study of structure, present in ecosystems. function, and change in a heterogenous land area Figure 1. Landscapes composed of interacting ecosystems. It is an in- A landscape consists of three main compo- consist of the matrix terdisciplinary science dealing with the interrela- nents: a matrix, patches, and corridors (Figure 1). (the dominant feature), tionship between human society and our living If we understand these components and their in- patches, and corridors that space. Landscape ecology is a relatively new sci- terrelationships, we can make better management connect the patches. ence, although Europeans decisions at the landscape level. have been using its prin- Matrix ciples much longer than Patch B Americans. We can learn Matrix corridor a great deal from examin- The matrix, the dominant component in the Patch A ing how the Europeans landscape, is the most extensive and connected have taken an almost landscape type, and it plays the dominant role in completely human-domi- landscape functioning. If we try to manage a habi- corridor nated landscape and at- tat without considering the matrix, we will likely tempted to restore fail to provide what wildlife need in that area. Patch C ecological functions to its For instance, if your goal is to enhance the systems. number of different species in a 40-acre forest patch surrounded by soybean fields, you will not create wildlife openings in the forest. That is, you will not want to create more edge (the outer zone of a patch that differs from its interior) because in an agricultural matrix, any type of opening will This publication is intended to be a companion to FOR-75, “An Ecosystems Approach create more and smaller forested patches in that to Natural Resources Management.” area, further reducing the amount of interior habi- It is well documented that adjacent habitats tat available to the wildlife that need it. affect each other through changes in microcli- The characteristics of matrix structure are the mates and the transfer of nutrients, materials, or density of the patches (porosity), boundary shape, seeds, etc. between communities. These changes networks, and heterogeneity. If an area has been ultimately affect ecological processes such as gene broken up but the patches are fairly close together, flow and species composition in each community. the patches are still dense enough to be useful for For example, breaking up the forest or creating animal movement. However, if you open up a large openings in the forest matrix creates smaller for- forested area by creating small openings, the est patches, with the matrix becoming open land patches may not be dense enough to sustain cer- (Figure 3). Thus, fragmentation of forest patches tain kinds of animals, and you could have a prob- results in drier microclimates, which: lem with predation on other wildlife by raccoons, • alter species composition and favor exotic, in- opossums, black rat snakes, or blue jays. A reduc- vasive species tion in density might also increase nest parasitism • increase the susceptibility of windthrow of ex- by brown-headed cowbirds on neotropical migrant isting trees songbirds. We can illustrate how lack of density • exacerbate a loss of forest interior wildlife spe- can create problems with brown-headed cowbirds. cies (like neotropical migrant songbirds) Some parts of eastern Kentucky do not have a large • reduce the genetic diversity of the remaining problem with brown-headed cowbirds because the populations, and matrix there is forested land. However, these birds • allow for the invasion of exotic, weedy species. pose a potential problem in other areas of eastern Ultimately, small preserves that are set aside Kentucky where the matrix has been highly frag- for their content may fail unless people intervene mented by coal mining, agriculture, and urban de- with intensive management, which is expensive velopment (Figure 2). and time consuming. To refer again to the example Boundary shape also has implications for of the glade, opening the surrounding forest habi- neotropical migrant birds and edge species of wild- tat increases the kinds and numbers of exotic plant life. The more uneven the boundary, the more species that overcome the rare plants unless in- edge. Within matrix areas, networks connect habi- tensive, site-specific management like herbicide tats of different size and shape, creating what is treatment, hand pulling, etc. is implemented. called heterogeneity within the landscape. These Similarly, fragmenting the forest surrounding a different habitat patches usually are replicated cave could alter the cave’s microclimate; certainly, throughout the matrix. nonpoint source pollution would alter its climate For example, the forests of eastern Kentucky vary and make the cave unsuitable for bats or other by slope, landscape position, and soil type. Ridgetop unique organisms like blind cavefish. forests are dominated by pine and oaks, cove sites are mixed hardwood stands, south- and west-fac- ing slopes are oak-hickory forest, etc. If a chance Patches event like a tornado were to occur, it might tear up Patches are nonlinear surface areas that differ one or two areas, but it would not wipe out all habi- in vegetation and landscape from their surround- tat for a species because the same habitat type is ings. They are units of land or habitat that are replicated several times in an area. The overall dam- heterogeneous when compared to the whole. They age to wildlife would not be as great because that include four different types: disturbance, remnant, type of habitat would still be close by. environmental resource, and introduced. • Disturbance patches are either natural or artifi- Context vs. Content cial. They result from various activities, includ- When natural resources are managed at the land- ing agriculture, forestry, urbanization, and scape level, context—where the biological element weather (i.e., tornados, hurricanes, ice storms, is placed in the landscape—is just as important as etc.). If left alone, a disturbance patch will even- content. In other words, you must consider the sur- tually change until it combines with the matrix. rounding matrix when attempting to conserve an • Remnant patches result when humans alter the area for its unique ecological attributes. Thus, if the landscape in an area and then leave parcels of land is being set aside to preserve rare plants (such the old habitat behind. Remnant patches are as wildflowers in a glade) or animals (such as bats generally more ecologically stable and persist in a cave), the content—or community—we are longer than disturbance patches. interested in is affected by the context of the envi- • Environmental resource patches occur because ronment if the surrounding landscape is altered. of an environmental condition such as a wet- land or cliff line. 2 Figure 2. Eastern Kentucky forest matrix has been fragmented by Figure 3. Notice how the forested matrix has begun to be converted to an mining, agriculture, and human habitation. “open lands” matrix. • Introduced patches are ones in which people est. Thus, from a habitat standpoint, the first im- have brought in nonnative plants or animals or portant concept is patch size, which determines rearranged native species. Animals moving from how much energy can be stored in that patch as one area to another can also bring in these well as the number of species that can reside there. nonnative elements. A larger patch can normally support a larger number of species and a greater variety of habitat types (Figure 4). Patches as Islands Several aspects of patches are important from an ecological perspective and affect landscape-level Worse Better management decisions. The approach used most often in analyzing patch habitats is to think of them Better as islands. Much of the current thinking about land- Size scape patch management has its roots in the theory of island biogeography. This theory was developed in 1967 by MacArthur and Wilson to explain the patterns of species diversity on oceanic islands. It Shape has also proven useful and applicable to a variety of ecological situations because an island is simply defined as a patch or parcel of favorable habitat surrounded by unfavorable habitat.

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