Comparison of several recent, publicly available and widely used land-cover products for the Eurasian Arctic revealed important differences in their representations of vegetation distribution. Such disparities have important implications for models that use these products as driving data sets to monitor vegetation and its role in carbon dynamics. The differences between GLC-2000 and MODIS.PFT a...

Nature’s services provided by green cover are important to environmental conditions in cities and their ability to adapt to climate change. Researchers using geospatial technologies have dramatically increased the spatial and temporal resolution of knowledge about the distribution of tree and shrub cover in cities. Much of the current research on tree cover in cities has concentrated on individ...

The snow-masking effect of vegetation exerts strong control on albedo in northern high latitude ecosystems. Large-scale changes in the distribution and stature of vegetation in this region will thus have important feedbacks to climate. The snow-albedo feedback is controlled largely by the contrast between snow-covered and snow-free albedo (Δα), which influences predictions of future warming in ...

DURING 2007, all laying hen producers within the McDonald’s Restaurants UK supply base (McDonald’s Restaurants UK source eggs from free-range UK producers) were required to plant, if not present already, 5 per cent of the total range area in trees. Noble Foods supply free-range eggs into a variety of food retailers not all of which require tree cover on the range. In this study, the authors inv...

We used data from regional forest inventories and research programs, coupled with mapped climatic and topographic information, to explore relationships and develop multiple linear regression (MLR) and regression tree models for total and deciduous shrub cover in the Oregon coastal province. Results from both types of models indicate that forest structure variables were most important for explai...

Knowledge about the land cover of large areas is important for monitoring and modeling of ecological and environmental processes and for land cover change detection. Considerable efforts have recently resulted in the development of global continuous fields for different land cover types at large spatial scales based on NOAA-AVHRR, SPOT-VEGETATION, and TERRA-MODIS data. Researchers have applied ...

Given a weighted undirected graph G = (V, E), a tree (respectively tour) cover of an edge-weighted graph is a set of edges which forms a tree (resp. closed walk) and covers every other edge in the graph. The tree (resp. tour) cover problem is of finding a minimum weight tree (resp. tour) cover of G. Arkin, Halldórsson and Hassin (1993) give approximation algorithms with factors respectively 3.5...

The tree and tour cover problems on an edge-weighted graph are to compute a minimum weight tree and closed walk, respectively, whose vertices form a vertex cover. Both problems are NP-hard. In this note we give strongly polynomial time, constant factor approximation algorithms for both problems. An interesting feature of our algorithms is how they combine approximations of other problems, namel...

As pinyon–juniper (specifically, Pinus monophylla and Juniperus osteosperma) woodlands in the western United States increase in distribution and density, understory growth declines and the occurrence of crown fires increases, leaving mountainsides open to both soil erosion and invasion by exotic species. We examined if the loss in understory cover that occurred with increasing tree cover was re...