Marybeth Buechner’s research while affiliated with University of California, Davis and other places

We report on the extent of disturbance (including habitat alteration and road and trail proliferation) in chaparral near urban development and analyze the effects of disturbance on small mammal and resident bird species. Disturbance patterns were evaluated in a 6700 ha study area in southern California: effects on mammals and birds were investigated by analyzing relationships between vegetation structure and animal species richness and abundance. Disturbance was prevalent throughout the study area and included extensive human-altered habitat (from past human activities such as vegetation clearing, human-caused fires, refuse dumping, and vegetation trampling) and 157 km of roads and trails. A nonsignificant trend was found between human-altered habitat and proximity to development, but human-altered habitat was significantly associated with roadway proximity. Trails were also more frequent near urban development and roads. Small mammals responded strongly to disturbance-related vegetation changes, while birds showed little or no response. Mammals endemic to chaparral vegetation were less diverse and abundant in disturbed sites, whereas disturbance-associated species increased in abundance. Close proximity of urban development to natural areas resulted in alteration of natural habitat and proliferation of roads and trails. Variation in life history traits between birds and mammals may affect response to disturbance and influence persistence if disturbance continues. Conservation efforts must recognize the potential for habitat damage and associated declines in native animal species caused by disturbance near urbanization and implement strategies to reduce these threats.

In recent years, cross-boundary management has become an essential part of park management. In this article we compare the perspectives of managers of several US national parks to the advice on this issue presented in the published literature. Data were obtained from interviews of the superintendents, assistant superintendents and resources managers of five major western national parks and from a survey of participants in a NPS workshop attended by park superintendents, scientists, and resource managers; law enforcement personnel; and interpreters. Three themes related to boundary management were consistently stressed by park managers: (10 a lack of sufficient funds and personnel within the parks; (2) the need for reliable information on both political and natural processes; and, (3) the importance of personal interactions between park staff and individuals from the surrounding area. Basic data collection, the documentation of trends, cooperative groups and personal contacts, educational programs, and land acquisition were the most useful strategies. A lack of funds and information, ineffective communication, enforcement problems, and a lack of motivation for parties to reach a negotiated agreement were the most serious obstacles. A wide range of valuable institutional knowledge concerning boundary management exists within the National Park Service; however, there appears to be a gap between published strategies and the approaches that work “on the ground”.

Protecting biodiversity on public lands is difficult, requiring the management of a complex array of factors. This is especially true when the ecosystems in question are affected by, or extend onto, lands outside the boundaries of the protected area. In this article we review recent developments in the cross-boundary management of protected natural resources, such as parks, wildlife reserves, and designated wilderness areas. Five ecological and 11 anthropic techniques have been suggested for use in cross-boundary management. The categories are not mutually exclusive, but each is a distinct and representative approach, suggested by various authors from academic, managerial, and legal professions. The ecological strategies stress the collection of basic data and documentation of trends. The anthropic techniques stress the usefulness of cooperative guidelines and the need to develop a local constituency which supports park goals. However, the situation is complex and the needed strategies are often difficult to implement. Diverse park resources are influenced by events in surrounding lands. The complexity and variability of sources, the ecological systems under protection, and the uncertainty of the effects combine to produce situations for which there are no simple answers. The solution to coexistence of the park and surrounding land depends upon creative techniques and recommendations, many still forthcoming. Ecological, sociological, legal, and economic disciplines as well as the managing agency should all contribute to these recommendations. Platforms for change include legislation, institutional policies, communication, education, management techniques, and ethics.

Landscape fragmentation is increasingly subdividing natural areas into semi-isolated remnants. Although such subdivision has benefits for some species, it often reduces the ability of an area to protect species that are sensitive to disturbance or prone to local extinction. Within protected areas, such as parks, landscape fragmentation results from road development. Roads both subdivide continuous habitat and act as corridors for the entry of materials, edge-adapted species, and disturbances into natural areas. We review the general effects of landscape fragmentation on sensitive species and the ecological effects of roads. We then combine this information with a pilot analysis of the extent to which our largest national parks are fragmented by roads. Our results indicate that substantial areas of our national parks are close enough to paved roads that they may be impacted by road effects. We consider the implications of this for park planning processes.

While a multi-disciplined approach is necessary to restore or protect threatened populations, it is difficult to achieve. This is especially true for mammalian carnivores. Considerable attention is payed to small population requirements for maintaining natural variation and obtaining genetic and demographic viability. Of the several subject areas crucial to conservation of species such as for carnivores, the authors stress: 1) use of space (species' large and small-scale area requirements for viable populations); 2) habitat capacity for protection (consequences of habitat fragmentation, including within reserves) and 3) extinction trajectories and density patterns that influence and are effected by population dynamics. The authors conclude by stating some changes in the breadth of planning that would assist in future conservation efforts of species such as for their case example, the mammalian carnivores. -Authors

Interest in the influence of landscape features on animal movement has been widespread; however, few field studies of the emigration of small mammals from patches of habitat directly consider the effects of the small-scale landscape features. The simulation models of Stamps et al. (1987a, b) and Buechner (1987a, b) suggest that the size of a dispersal sink relative to the size of the source patch, the average distance traveled by dispersers in the sink, the ease with which dispersers cross the edge between the sink and a source patch, and source patch perimeter:area ratio may all be important influences on emigration rates. A review of field studies of small mammal dispersal into sinks suggests that in a substantial fraction of such studies the values of these factors fall within the ranges that the simulation models indicate have the greatest potential effect on emigration rates. New field studies of dispersal sinks that include a consideration of these factors are necessary in order to evaluate the magnitude of the impact of these factors on natural populations.

Many parks represent insular areas of habitat and the movement of animals across park boundaries can be critical to park wildlife populations. I use computer simulation models in order to analyse factors affecting the movement and density of animals in patches of habitat (Buechner, 1987b; Stamps et al., 1987; in press). The results suggest that the perimeter: area ratios and edge permeability of parks, the appearance and stopping patterns and habitat preferences of moving animals, and the relative size of dispersal sinks and source pools can all potentially influence the direction and magnitude of the movement of animals across the park boundaries.The results suggest that scientists interested in park and reserve design n to consider other factors than just the size of potential sites, particularly park perimeter: area ratios. The simulations also suggests a strategy for solving some types of conservation and control problems by manipulating sinks or pools: (1) identify which factors can be practically altered in a given situation, (2) evaluate those factors to estimate their current levels, and (3) focus on the factor which is nearest the lower end of its range of values.

Computer simulation models were used to explore the effect of habitat geometry on intruder pressure for territories in different locations within a patch of uniformly high quality habitat, for territories in patches of different shapes and sizes, and for patches surrounded by different types of suboptimal habitats. In models in which the edges of the habitat patch are impermeable (hard-edged), intruders do not leave the central territorial habitat, H, and intruder pressure is lower for territories on the edge of H than for more centrally located territories. Average intruder pressure for any given loop of territories (⁠IP¯i⁠, for loop = i) is positively related to both the proportion of territories on the edge of the patch (ESR) and the average distance moved by intruders. In models in which the edges of H are permeable (soft-edged), intruders are able to move between H and the surrounding habitats, which were of two types: sinks (no intruders generated there) and reserves (a source of intruders). The presence of sinks dramatically reduces both IP¯i and average intruder pressure over H (⁠IPH¯⁠) as compared to hard-edged habitats, and both IP¯i and IPH¯ are negatively related to the proportion of territories on the edge of the patch (ESR). Conversely, IP¯i and IPH¯ are positively related to ESR when the surrounding habitat acts as an intruder-reserve. Data from empirical studies of territorial species agree with many of the direct and indirect qualitative predictions of these models. The effects of habitat geometry on defense costs may be important in many territorial species, and should be taken into account in future studies.