Treesearch

Understanding how tree size impacts leaf- and crown-level gas exchange is essential to predicting forest yields and carbon and water budgets. The stable carbon isotope ratio of organic matter has been used to examine the relationship of gas exchange to tree size for a host of species because it carries a temporally integrated signature of foliar photosynthesis and stomatal conductance. The carbon isotope composition of leaves reflects discrimination against 13C relative to 12C during photosynthesis and is the net result of the balance of change in CO2 supply and demand at the sites of...

More frequent fires under climate warming are likely to alter terrestrial carbon (C) stocks by reducing the amount of C stored in biomass and soil. However, the thresholds of fire frequency that could shift landscapes from C sinks to C sources under future climates are not known. We used the Greater Yellowstone Ecosystem (GYE) as a case study to explore the conditions under which future climate and fire regimes would result in tipping points of C source-sink dynamics. We asked: How great a change in climate and fire regime would be required to shift conifer forests in the GYE from a net C...

Climate change is likely to alter wildfire regimes, but the magnitude and timing of potential climate-driven changes in regional fire regimes are not well understood. We considered how the occurrence, size, and spatial location of large fires might respond to climate projections in the Greater Yellowstone ecosystem (GYE) (Wyoming), a large wildland ecosystem dominated by conifer forests and characterized by infrequent, high-severity fire. We developed a suite of statistical models that related monthly climate data (1972-1999) to the occurrence and size of fires >200 ha in the northern...

In 2007-2008, some visitors to Taroko National Park in Taiwan were surveyed to allow testing of a behavioral prediction model in the context of national park recreation. This model includes three constructs: values (a cultural anthropology factor), perceptions of service quality (service marketing factors), and perceptions of crowding (a national park recreation factor). We obtained a sample of 1,080 visitors. Multiple regression analysis was used to test the predictive power of values dimensions, service quality dimensions and a crowding index on behavioral intentions and behaviors. From...

This paper identifies and describes some of the values associated with tropical rain forests in their natural and near-natural conditions. Tropical rain forests are moist forests in the humid tropics where temperature and rainfall are high and the dry season is short. These closed (non-logged) and broad-leaved forests are a global resource. Located almost entirely in developing countries, where populations are expected to double in the next 25 years, tropical forests are extremely important to all life everywhere on the planet.

This study evaluates the quality of planning objectives for visitor services as written in Comprehensive Conservation Plans for the National Wildlife Refuge System of the United States. Planners in the U.S. Fish and Wildlife Service are predominantly writing public use objectives that address wildlife recreation and education. Results indicate that planners are writing visitor services objectives that are achievable and results oriented. Overall quality of objectives has improved since the Refuge Improvement Act of 1997. The highest quality objectives identified target audiences, accounted...

The Federal Land Policy & Management Act of 1976 directed the Bureau of Land Management (BLM) to inventory its lands for wilderness characteristics and to protect identified areas as "wilderness study areas" (WSAs) until acted upon by Congress. BLM conducted these inventories and studies between 1976 and 1991, finding nearly 800 areas totaling 9.6 million hectares to possess wilderness characteristics. The remaining areas, released from "interim management" protection, were expected to be further degraded by uses not allowed within WSAs. In the ensuing 20 to 30 years, however, a surprising...

Since 1998, the wilderness values of Antarctica have been among those given legal recognition under the Protocol on Environmental Protection to the Antarctic Treaty. Despite the legal obligation, on-the-ground implementation has attracted little interest. The term "wilderness" and its consequential operational implication, including the designation of Antarctic Specially Protected Areas and the drafting of Environmental Impact Assessments, is still poorly conceptualized in Antarctic Treaty System discourse. Many possible factors underlie the lack of attention to the protection of wilderness...

The Intergovernmental Panel on Climate Change (IPCC) (2007) reports a likely 2 °C to 4.5 °C temperature rise in the upcoming decades. This warming is likely to affect ecosystems and their ability to provide services that benefit human well-being. Ecosystem services valuation (ESV), meanwhile, has emerged as a way to recognize the economic value embodied in these services that is not currently reflected in markets. To contribute to better understanding of how U.S. conservation lands may be affected by climate change, we outline a method and preliminary estimates of the value of ecosystem...

The National Parks Conservation Association’s Center for State of the Parks uses an easily explained, fact-based methodology to determine the condition of natural and cultural resources in the United States National Park System. Researchers assess and numerically score natural resources that include water quality and quantity, climate change impacts, forest fragmentation, wildlife communities, non-native species, poaching, and land use history. Evaluated cultural resources include archaeology, historical structures, relations with indigenous communities, and cultural landscapes. By using...