Land ownership and landscape structure: a spatial analysis of sixty-six Oregon (USA) Coast Range watersheds

Patterns of land ownership and forest cover are related in complex and ecologically significant ways. Using a Geographic Information System and regression analysis, we tested for spatial relationships between the structure of land ownership and forest cover across 66 watersheds in the state of Oregon (USA), Coast Range mountains. We found that in these watersheds (1) forest cover diversity increased with land ownership diversity, (2) size of forest patches increased with size of land ownership patches, and (3) connectivity of forest cover increased with connectivity of land ownership. Land ownership structure explained between 29% and 40% of the variability of forest cover structure across these watersheds. Driving this relationship are unique associations among particular ownership classes and various forest cover classes. The USDA Forest Service and the USDI Bureau of Land Management were associated with mature forest cover; private industry was associated with young forest cover; nonindustrial private forest owners were associated with a wide diversity of cover classes. Watersheds with mixed ownership appear to provide greater forest cover diversity, whereas watersheds with concentrated ownership provide less diverse but more connected forest cover. Results suggest that land ownership patterns are strongly correlated with forest cover patterns. Therefore, understanding landscape structure requires consideration of land ownership institutions, dynamics, and patterns.This revised version was published online in May 2005 with corrections to the Cover Date.     

Research article Canopy dynamics and human caused disturbance on a semi-arid landscape in the Rocky Mountains,USA

Invasion of grasslands by woody plants has been identified as a key indicator of changes in ecosystem structure and function in arid and semi-arid rangelands throughout the world. We investigated changes in the balance between woody and herbaceous components of a semi-arid landscape in western Colorado (USA) using historical aerial photography. Aerial photographs from 1937, 1965–67, and 1994 were sampled at matched locations within overlapping photographs. We modeled change in spatial pattern and heterogeneity across the entire landscape and found a small, net decrease in woody canopy cover; however means disguised normal distributions of change that demonstrated offsetting increases and decreases. We described a region of widespread canopy decline within piñon-juniper forests between 2300 and 2600 m (7500–8500 feet) and a region of predominant increase at lower elevations, between 1800 and 2250 m (5900–7400 feet). It remains unclear whether this shift was driven by climate or by human-caused or natural disturbance. Mean conifer cover decreased within coniferous forests, which counteracted a trend of increased conifer cover in mixed forests, savanna-like woodlands, and the shrub steppe. Disturbance had a significant interaction with cover change in several communities, including forests, savanna and shrublands. Anthropogenic disturbances counteracted successional trends toward canopy closure more than wildfires, but this did not entirely explain observed canopy decline. The natural dynamics in this region also caused diverse changes rather than a simple progression towards increased forest cover. Importantly, temporal change in vegetation varied spatially across the landscape illustrating the importance of landscape level, spatially explicit analyses in characterizing temporal dynamics.     

Effects of land-cover change on spatial pattern of forest communities in the Southern Appalachian Mountains (USA)

Landscape Ecology - Understanding the implications of past, present and future patterns of human land use for biodiversity and ecosystem function is increasingly important in landscape ecology. We...     

Bird populations in native forest patches in south-eastern Australia: the roles of patch width,matrix type (age) and matrix use

We surveyed birds in patches of native eucalypt forest and in surrounding exotic matrix (Radiata pine forests) in south-eastern Australia. Our objectives were: (1) to examine the influence of the width of native forest patches and the age of surrounding pine forests on bird occurrence in patches of native forest; and (2) to verify the relationship between the use of the surrounding pine matrix and bird species response to variation in width of patches of native forests. A total of 32 study sites (boundaries between eucalypt and pine forests) were surveyed. Birds were counted by the area search method within 0.5-ha quadrats. Data were analysed using generalised linear models. Wide patches of eucalypt forest supported higher species richness and greater numbers of birds, such as foliage searchers and nectarivores, than narrow patches. Matrix age also influenced the occurrence of some species in native patches. The abundance of species in wide and narrow patches of native forest was related to their use of the matrix. This was true for native forests surrounded by old but not by young pine forests. We suggest that management in wood production landscapes take into account both characteristics of native patches and the surrounding matrix. Negative impacts of fragmentation in managed landscapes might be reduced by promoting matrix types that are suitable for bird species.     

Biophysical and socioeconomic factors explaining the extent of forest cover on private ownerships in a Midwestern (USA) agrarian landscape

As landscape fragmentation continues to escalate, it is imperative that we improve our understanding of the factors that contribute to the creation and retention of forest on privately-owned land to most effectively design and implement conservation policy. This article presents the percentages of variation in the proportion of forest on private ownerships across an agriculturally-dominated landscape in north-central Indiana, USA that can be explained by biophysical characteristics, landowner (socioeconomic) attributes, and private landowner assistance programs. While biophysical characteristics of the land accounted for the majority of variation explained (17.35%, p < 0.0001, n = 194), attitudinal and demographic attributes of the landowners contributed significantly to explaining additional variation (7.97%, p<0.0001), and overlapped with biophysical characteristics to explain another 17.31%. Program familiarity and enrollment did not explain a significant amount of the variation independent of either biophysical or landowner attributes. Private landowner assistance programs should broaden their objectives and increase incentives to appeal to the variety of landowners who possess the decision-making authority for most of the land in the region and the nation as a whole.     

Cumulative effects of roads and logging on landscape structure in the San Juan Mountains,Colorado (USA)

In the southern Rocky Mountains of temperate North America, the effects of Euro-American activities on disturbance regimes and landscape patterns have been less ubiquitous and less straightforward in high-elevation landscapes than in low-elevation landscapes. Despite apparently little change in the natural disturbance regime, there is increasing concern that forest management activities related mainly to timber harvest and to the extensive network of roads constructed to support timber harvest, fire control, and recreation since the late 1800s have altered disturbance regimes and landscape structure. We investigated the magnitude of change in landscape structure resulting from roads and logging since the onset of timber harvest activities in 1950. We found limited evidence for significant impacts in our study area when all lands within the landscape were considered. The relatively minor changes we observed reflected the vast buffering capacity of the large proportion of lands managed for purposes other than timber (e.g., wilderness). Significant changes in landscape structure and fragmentation of mature forest were, however, evident on lands designated as suitable timberlands. Roughly half of the mature coniferous forest was converted to young stands; mean patch size and core area declined by 40% and 25%, respectively, and contrast-weighted edge density increased 2- to 3-fold. Overall, roads had a greater impact on landscape structure than logging in our study area. Indeed, the 3-fold increase in road density between 1950–1993 accounted for most of the changes in landscape configuration associated with mean patch size, edge density, and core area. The extent of area evaluated and the period over which change was evaluated had a large impact on the magnitude of change detected and our conclusions regarding the ecological significance of those changes. Specifically, the cumulative impact on landscape structure was negligible over a 10-year period, but was notable over a 40-year period. In addition, the magnitude of change in landscape structure between 1950–1993 varied as a function of landscape extent. At the scale of the 228000 ha landscape, change in landscape structure was trivial, suggesting that the landscape was capable of fully incorporating the disturbances with minimal impact. However, at intermediate scales of 1000–10000 ha landscapes, change in landscape structure was quite evident, suggesting that there may be an optimal range of scales for detecting changes in landscape structure within the study area.