Landscape heterogeneity and the role of corridors in determining the spatial structure of insular mammal populations.

Characterizing the influence of landscape features on assessments of isolation is critical to understanding dispersal, and, ultimately, the structure of native communities in fragmented ecosystems. At the same time, a comprehensive understanding of such landscape features, especially corridors, requires assessing corridors individually and incorporating the habitat needs of relevant species. By considering biologic responses to fragmentation at appropriate scales, we can work to maintain natural processes and preserve natural levels of biodiversity.Ecological landscapes are often viewed as heterogeneous mosaics of suitable habitat interspersed within a suboptimal matrix. Fragmentation of such landscapes has altered the natural patterns of these mosaics. As a result, processes such as immigration have also been altered, with dire consequences on biodiversity. I assessed how anthropogenic influences on the Olympic National Forest, Washington, have affected landscape measures of isolation and resulting species diversity. I assessed alternative indices of isolation for sites located in three types of old-growth forest: fragments, corridors, and continuous forest. These isolation indices vary in how they identify sources of colonizers and in their characterization of the landscape matrix. I compared levels of variance and redundancy among these measures to ascertain the most relevant index for assessing isolation. I then focused on the role of corridors in ameliorating the effects of fragmentation by decreasing isolation. To assess such corridor utility, I quantified among-and within-corridor variability in community structure, landscape indices, and habitat descriptors.Although highly correlated, optimal measures of isolation varied among types of sites. The influence of corridors on species responses to isolation was shown to be very strong. While variability in species assemblages and habitat was very high among the four corridors studied, such variability was low along individual corridors. This suggests that although these corridors appeared to be effective through their entirety, possibly acting as demographic sources of individuals, they should not be considered equivalent to one another

The Balloon-Borne Large Aperture Submillimeter Telescope (BLAST) 2005: A 10 deg^2 Survey of Star Formation in Cygnus X

We present Cygnus X in a new multi-wavelength perspective based on an unbiased BLAST survey at 250, 350, and 500 micron, combined with rich datasets for this well-studied region. Our primary goal is to investigate the early stages of high mass star formation. We have detected 184 compact sources in various stages of evolution across all three BLAST bands. From their well-constrained spectral energy distributions, we obtain the physical properties mass, surface density, bolometric luminosity, and dust temperature. Some of the bright sources reaching 40 K contain well-known compact H II regions. We relate these to other sources at earlier stages of evolution via the energetics as deduced from their position in the luminosity-mass (L-M) diagram. The BLAST spectral coverage, near the peak of the spectral energy distribution of the dust, reveals fainter sources too cool (~ 10 K) to be seen by earlier shorter-wavelength surveys like IRAS. We detect thermal emission from infrared dark clouds and investigate the phenomenon of cold ``starless cores" more generally. Spitzer images of these cold sources often show stellar nurseries, but these potential sites for massive star formation are ``starless" in the sense that to date there is no massive protostar in a vigorous accretion phase. We discuss evolution in the context of the L-M diagram. Theory raises some interesting possibilities: some cold massive compact sources might never form a cluster containing massive stars; and clusters with massive stars might not have an identifiable compact cold massive precursor.Comment: 42 pages, 31 Figures, 6 table

Watershed Development and Sediment Accumulation in a Small Urban Lake

The ever-increasing development of watersheds has raised the importance of assessing and mitigating the environmental impacts on water bodies located within disturbed areas. The removal of natural landcover can increase soil erosion and runoff along creeks and rivers, leading to heavier sediment build-up in ponds and lakes and to reductions in water quality and impoundment capabilities. For this paper, we described the possible impact from urbanization on sedimentation within a small lake. Landcover maps from two different time periods were compared against lake depths to assess relationships between development and sediment buildup. By understanding the mechanisms potentially leading to the ultimate loss of this lake, it is hoped that remediation strategies to reduce future degradation may be developed

Mass-losing Semiregular Variable Stars in Baades Windows

By cross-correlating the results of two recent large-scale surveys, the general properties of a well-defined sample of semiregular variable stars have been determined. ISOGAL mid-infrared photometry (7 and 15 μm) and MACHO V and R light curves are assem