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Matthew Petrie

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Population-based habitat conservation planning for migrating and wintering waterfowl in North America is carried out by habitat Joint Venture (JV) initiatives and is based on the premise that food can limit demography (i.e. food limitation hypothesis). Consequently, planners use bioenergetic models to estimate food (energy) availability and population-level energy demands at appropriate spatial and temporal scales, and translate these values into regional habitat objectives. While simple in principle, there are both empirical and theoretical challenges associated with calculating energy supply and demand including: 1) estimating food availability, 2) estimating the energy content of specific foods, 3) extrapolating...
Categories: Publication; Types: Citation; Tags: Wildfowl
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The persistence of ponderosa pine and lodgepole pine forests in the 21st century depends to a large extent on how seedling emergence and establishment are influenced by driving climate and environmental variables, which largely govern forest regeneration. We surveyed the literature, and identified 96 publications that reported data on dependent variables of seedling emergence and/or establishment and one or more independent variables of air temperature, soil temperature, precipitation and moisture availability. Our review suggests that seedling emergence and establishment for both species is highest at intermediate temperatures (20 to 25 °C), and higher precipitation and higher moisture availability support a higher...
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Ponderosa pine forests are declining and their future persistence is uncertain. Most research on forest declines has focused on the effects of disturbances including wildfire, insect outbreaks, and severe drought on mortality of mature trees. Yet, recent research suggests that ponderosa pine declines may be even more severe as these ecosystems fail to regenerate naturally (i.e. grow from seed to adulthood) in a climate that is becoming increasingly less favorable for juvenile tree survival. For land managers to accurately assess and combat the risk of failed regeneration, it is critical to better understand the many factors supporting regeneration across the diverse habitats where these ecosystems are located. ...
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