Treesearch

Research on patterns of below-ground carbon (C) storage in urban lawns has focused on biogeochemical mechanisms, with human activities playing an important but somewhat secondary role. By contrast, studies of above-ground vegetation in urban areas have emphasized socioeconomic factors that influence greenness, abundance, and diversity, without explicitly considering biogeochemical mechanisms. Here we examine how both biogeochemical and socioeconomic factors influence patterns of C storage in urban yards both above- and below-ground. We combined measurements of above- and below-ground C...

This study uses individual survey data to investigate the impact of information about hiking destinations on estimated wilderness values in a spatial context. The data is derived from a revealed preference survey of backcountry visitors who responded to questions about their recreation behavior in the San Jacinto Wilderness of southern California. Two GIS data layers are developed showing spatial representations of non-market values derived from a Kuhn- Tucker demand model, with and without destination information. Each pixel in each data layer contains an estimate of the recreation value...

Fire exclusion since the 1930s across western U.S. landscapes has greatly altered fire regimes and fuel conditions. After a lightning-caused fire swept through the center of the Bob Marshall Wilderness Area in 2003, researchers initiated a comprehensive study along the South Fork of the Flathead River. This study assessed the post-fire survival of over 600 iconic, relict ponderosa pine trees. These trees are of great interest as they are ancient (>400 years old), and some have Native American bark-peeling scars and fire scars. This area had not seen fire since 1910, if not earlier, despite...

Tree death is a natural part of forest dynamics, yet is not often studied over long periods, particularly in temperate mixed-species hardwood stands. In this study, we evaluated stand dynamics of four reference plots on each of the West Virginia Long-term Soil Productivity (LTSP) Studies. The Fork Mountain LTSP Study was initiated in 1996 and the Middle Mountain LTSP Study in 1997. The two locations represent distinct stand types (mixed mesophytic and cherry-maple) and site conditions (elevation, parent material, aspect). We found that after 20 years, there were differences in patterns of...

In addition to their role as critical ecological resources, the forests and wetlands of urban parks are integral to the social and psychological well-being of many city residents. In this study, we use randomized field interviews with 955 New York City park users to explore differences in park use and motivations for park visitation according to site type and gender of respondents. We find that natural areas offer different experiences and social meanings to park visitors compared to the ballfields, lawns, and playgrounds of landscaped areas. Visitors to urban forests and wetlands are more...

Forest monocultures are generally considered to alter the microbial community, reduce soil fertility, and presumably reduce forest productivity compared to mixed species in plantations or mixed species in natural stands. As the mechanisms of alteration of soils by monocultures have not been elucidated very well, we compared indicators of stand productivity and soils in three forest types all growing on the same soils that developed under the natural forests of the Maoershan Forest Farm in northeastern China. The three forest types were a planted monoculture of Larix plantation but where...

A previous review of earthworm impacts on greenhouse-gas emissions concluded that earthworms elevated soil CO2 emissions with no apparent influence on soil organic carbon (SOC), especially in laboratory incubations and in agroecosystems. This conclusion suggests that the elevated soil CO2 emissions may come from enhanced plant litter decomposition. Despite the known important role of earthworms on regulating ecosystem processes, a quantitative analysis of the relationship between earthworms and decomposition in global terrestrial ecosystems is still missing. Here, we present a quantitative...

Shade-tolerant, fire-intolerant tree species are expanding in historically oak-dominated landscapes in the central and eastern U.S. Once established, these species are hypothesized to accelerate their own expansion through canopy, bark, and leaf litter traits that decrease forest flammability, consequently hindering the growth and survival of pyrophytic, shade-intolerant upland oaks (Quercus spp.). To better understand how canopy, bark, and leaf litter traits associated with flammability differ between oaks and common competitors, we quantified these traits in an upland oak forest in...

Wildfires are increasingly common in the United States, the result of climate change, altered wildfire regimes, and expanding residential development in close proximity to wildland vegetation. Both suppression expenditures and damages are increasing as a result. Accelerating wildfire losses have been observed in other countries as well: Australia, Canada, Chile, Greece, and Portugal have all experienced record destruction due to wildfires in the past decade. Reducing wildfire losses is a daunting goal requiring a multi-part strategy across all levels of government. In the U.S., federal...

A growing body of research shows that plant genetic factors can influence ecosystem processes and structure communities, but one aspect that has received little study is sex differentiation in dioecious plants. Since headwater streams are reliant on riparian leaf litterfall, plant sex differences in leaf traits may influence in-stream processes. Sitka willow (Salix sitchensis) at Mount St. Helens is dioecious and heavily infested with the stem-boring weevil (Cryptorhynchus lapathi), which causes branch dieback and summer litterfall. We found that female willow shrubs tend to grow closer to...