Stephen C. Trombulak

Conservation planners are faced with numerous choices regarding ‘what to connect’ when modeling landscape networks on an ecoregion scale. A simplifying assumption is often that coarse-scale corridors may provide overlapping or ‘umbrella’ effects for multiple conservation scenarios. To examine this, we assessed differences in connectivity models arising from four different conservation scenarios for the transboundary Northern Appalachian/Acadian Ecoregion (330,000 km²). Models resulted in networks comprised of varying levels of connectedness, suggesting the presence of local connectivity at several sub-ecoregion scales, but diminished ecoregion-scale connectivity. Our results also indicate that selecting ‘what to connect’ at the ecoregion scale strongly influences the location and extent of modeled corridors. Further, our evidence suggests that landscape networks derived for one scenario are not likely to produce far-reaching corridor umbrellas or highly coincident landscape networks for alternative conservation scenarios with varying goals. As a result, alternative landscape networks should not be considered functionally equivalent.

We have analyzed twentieth‐century temperature data from 73 climate stations in New England and New York. Linear regression gives a 100‐year temperature change (ΔT₁₀₀) for each station. All but two stations show an increase over this time, giving a regional area‐weighted average ΔT₁₀₀ of 1.11°C. Average ΔT₁₀₀ values for each state are all positive, ranging from 0.86°C to 1.86°C. Spatial autocorrelation analysis reveals a southeastern New England cluster of stations with relatively large ΔT₁₀₀, and a cluster in western New York with low but still positive ΔT₁₀₀. Thus, at differing spatial scales, temperature in this region increased during the twentieth century, in most cases by more than the global average increase of some 0.6°C during this same period. Our results contrast markedly with the New England Regional Assessment, and may have implications for other regional assessments undertaken under the auspices of the U.S. Global Change Research Program.

Roads are a widespread and increasing feature of most landscapes. We reviewed the scientific literature on the ecological effects of roads and found support for the general conclusion that they are associated with negative effects on biotic integrity in both terrestrial and aquatic ecosystems. Roads of all kinds have seven general effects: mortality from road construction, mortality from collision with vehicles, modification of animal behavior, alteration of the physical environment, alteration of the chemical environment, spread of exotics, and increased use of areas by humans. Road construction kills sessile and slow‐moving organisms, injures organisms adjacent to a road, and alters physical conditions beneath a road. Vehicle collisions affect the demography of many species, both vertebrates and invertebrates; mitigation measures to reduce roadkill have been only partly successful. Roads alter animal behavior by causing changes in home ranges, movement, reproductive success, escape response, and physiological state. Roads change soil density, temperature, soil water content, light levels, dust, surface waters, patterns of runoff, and sedimentation, as well as adding heavy metals (especially lead), salts, organic molecules, ozone, and nutrients to roadside environments. Roads promote the dispersal of exotic species by altering habitats, stressing native species, and providing movement corridors. Roads also promote increased hunting, fishing, passive harassment of animals, and landscape modifications. Not all species and ecosystems are equally affected by roads, but overall the presence of roads is highly correlated with changes in species composition, population sizes, and hydrologic and geomorphic processes that shape aquatic and riparian systems. More experimental research is needed to complement post‐hoc correlative studies. Our review underscores the importance to conservation of avoiding construction of new roads in roadless or sparsely roaded areas and of removal or restoration of existing roads to benefit both terrestrial and aquatic biota.