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Bird Richness and Abundance in Response to Urban Form in a Latin American City
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There is mounting evidence that urban areas influence biodiversity. Generalizations how- ever require that multiple urban areas on multiple continents be examined. Here we evaluated the role of urban areas on avian diversity for a South American city, allowing us to examine the effects of urban features common worldwide, using the city of Valdivia, Chile as case study. We assessed the number of birds and their relative abundance in 152 grid cells of equal size (250 m2) distributed across the city. We estimated nine independent variables: land cover diversity (DC), building density (BD), impervious surface (IS),municipal green space (MG),non-municipal green space (NG), domestic garden space (DG), distance to the periphery (DP), social welfare index (SW), and vegetation diversity (RV). Impervious surface represent 41.8% of the study area, while municipal green, non-municipal green and domestic garden represent 11.6%, 23.6% and 16% of the non- man made surface. Exotic vegetation species represent 74.6% of the total species identified across the city. We found 32 bird species, all native with the exception of House Sparrow and Rock Pigeon. The most common species were House Sparrow and Chilean Swallow. Total bird richness responds negatively to IS and MG, while native bird richness responds positively to NG and negatively to BD, IS DG and, RV. Total abundance increase in areas with higher values of DC and BD, and decrease in areas of higher values of IS, SW and VR. Native bird abundance responds positively to NG and negatively to BD, IS MG, DG and RV. Our results suggest that not all the general patterns described in previous studies, conducted mainly in the USA, Europe, and Australia, can be applied to Latin American cities, having important implications for urban planning. Conservation efforts should focus on non-municipal areas, which harbor higher bird diversity, while municipal green areas need to be improved to include elements that can enhance habitat quality for birds and other species. These findings are relevant for urban planning in where both types of green space need to be considered, especially non-municipal green areas, which includes wetlands, today critically threatened by urban development.
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Characterizing coal and mineral mines as a regional source of stress to stream fish assemblages
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Mining impacts on stream systems have historically been studied over small spatial scales, yet investigations over large areas may be useful for characterizing mining as a regional source of stress to stream fishes. The associations between co-occurring stream fish assemblages and densities of various “classes” of mining occurring in the same catchments were tested using threshold analysis. Threshold analysis identifies the point at which fish assemblages change substantially from best available habitat conditions with increasing disturbance. As this occurred over large regions, species comprising fish assemblages were represented by various functional traits as well as other measures of interest to management (characterizing reproductive ecology and life history, habitat preferences, trophic ecology, assemblage diversity and evenness, tolerance to anthropogenic disturbance and state-recognized game species). We used two threshold detection methods: change-point analysis with indicator analysis and piecewise linear regression. We accepted only those thresholds that were highly statistically significant (p 0.01) for both techniques and overlapped within 5% error. We found consistent, wedge-shaped declines in multiple fish metrics with increasing levels of mining in catchments, suggesting mines are a regional source of disturbance. Threshold responses were consistent across the three ecoregions occurring at low mine densities. For 47.2% of the significant thresholds, a density of only 0.01 mines/km2 caused a threshold response. In fact, at least 25% of streams in each of our three study ecoregions have mine densities in their catchments with the potential to affect fish assemblages. Compared to other anthropogenic impacts assessed over large areas (agriculture, impervious surface or urban land use), mining had a more pronounced and consistent impact on fish assemblages. Threshold analysis Fish functional traits Landscape influences Game fishes Mining Rivers
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Climate change-associated tree mortality increases without decreasing water availability
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Here, we reveal temporally increasing tree mortality across all study species over the last three decades in the central boreal forests of Canada, where long-term water availability has increased without apparent climate change-associated drought. Our results suggest that the consequences of climate change on tree mortality are more profound than previously thought.
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Comparative Drought Responses of Quercus ilex L. and Pinus sylvestris L. in a Montane Forest Undergoing a Vegetation Shift
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Different functional and structural strategies to cope with water shortage exist both within and across plant communities. The current trend towards increasing drought in many regions could drive some species to their physiological limits of drought tolerance, potentially leading to mortality episodes and vegetation shifts. In this paper, we study the drought responses of Quercus ilex and Pinus sylvestris in a montane Mediterranean forest where the former species is replacing the latter in association with recent episodes of drought-induced mortality. Our aim was to compare the physiological responses to variations in soil water content (SWC) and vapor pressure deficit (VPD) of the two species when living together in a mixed stand or separately in pure stands, where the canopies of both species are completely exposed to high radiation and VPD. P. sylvestris showed typical isohydric behavior, with greater losses of stomatal conductance with declining SWC and greater reductions of stored non-structural carbohydrates during drought, consistent with carbon starvation being an important factor in the mortality of this species. On the other hand, Q. ilex trees showed a more anisohydric behavior, experiencing more negative water potentials and higher levels of xylem embolism under extreme drought, presumably putting them at higher risk of hydraulic failure. In addition, our results show relatively small changes in the physiological responses of Q. ilex in mixed vs. pure stands, suggesting that the current replacement of P. sylvestris by Q. ilex will continue.
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Conservation Easements and Climate Change
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The current law of conservation easements does not recognize the full potential for carbon capture.
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Conservation easements and global climate change
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Land conservation is necessary to combat the ills of climate change and environmental degradation. The warming of the climate system is unequivocal. The Intergovernmental Panel on Climate Change (IPCC) recently released an updated report regarding the existence and impacts of global climate change. The report noted that the “resilience of many ecosystems is likely to be exceeded this century by an unprecedented combination of climate change, associated disturbances (e.g., flooding, drought, wildfire, insects, ocean acidification) and other global climate change drivers (e.g., land use change, pollution,fragmentation of natural systems, overexploitation of resources).”
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CONSERVATION EASEMENTS AT THE CLIMATE CHANGE CROSSROADS
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This article examines the conundrum that occurs when climate change leads to a landscape that conflicts with conservation easement terms. In facing the challenge of a disconnect between conservation easements and a changing world, there are two main tacks. First, conservationists can make conservation easements fit the changing landscape. Second, conservationists can change the landscape to fit the conservation easements. Both of these options present challenges and conflict with the essence of the conservation easement tool. A conservation easement that is too changeable endangers the perpetual protection that is the cornerstone of conservation easements. But, forcing the landscape to fit a conservation easement requires active management, something more often associated with fee-simple ownership. The solution to using conservation easements in a changing world lies somewhere between these two extremes, with the most important level of analysis being an assessment of when to use conservation easements.
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Conservation in a social-ecological system experiencing climate-induced tree mortality
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We present a social-ecological framework to provide insight into climate adaptation strategies and diverse perspectives on interventions in protected areas for species experiencing climate-induced impacts. To develop this framework, we examined the current ecological condition of a culturally and commercially valuable species, considered the predicted future effects of climate change on that species in a protected area, and assessed the perspectives held by forest users and managers on future adaptive practices. We mapped the distribution of yellow-cedar (Callitropsis nootkatensis) and examined its health status in Glacier Bay National Park and Preserve by comparing forest structure, tree stress-indicators, and associated thermal regimes between forests inside the park and forests at the current latitudinal limit of the species dieback. Yellow-cedar trees inside the park were healthy and relatively unstressed compared to trees outside the park that exhibited reduced crown fullness and increased foliar damage. Considering risk factors for mortality under future climate scenarios, our vulnerability model indicated future expected dieback occurring within park boundaries. Interviews with forest users and managers revealed strong support for increasing monitoring to inform interventions outside protected areas, improving management collaboration across land designations, and using a portfolio of interventions on actively managed lands. Study participants who perceived humans as separate from nature were more opposed to inter- ventions in protected areas. Linking social and ecological analyses, our study provides an interdisciplinary approach to identify system-specific metrics (e.g., stress indicators) that can better connect monitoring with management, and adaptation strategies for species impacted by climate change.
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Contrasting futures for ocean and society from different anthropogenic CO2 emissions scenarios
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The ocean moderates anthropogenic climate change at the cost of profound alterations of its physics, chemistry, ecology, and services. Here, we evaluate and compare the risks of impacts on marine and coastal ecosystems—and the goods and services they provide—for growing cumulative carbon emissions under two contrasting emissions scenarios. The current emissions trajectory would rapidly and significantly alter many ecosystems and the associated services on which humans heavily depend. A reduced emissions scenario — consistent with the Copenhagen Accord’s goal of a global temperature increase of less than 2°C — is much more favorable to the ocean but still substantially alters important marine ecosystems and associated goods and services. The management options to address ocean impacts narrow as the ocean warms and acidifies.
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