B13D-01 13:40h
A Framework for Assessing Ecosystem Responses to Land Use Change
Land use change, including conversion of the landscape and intensification of already-converted landscapes, is one of today's most pervasive global environmental changes. Ecosystems respond to land use change in myriad ways, ranging for changes in habitat, hydrology, climate, to human health. These multiple responses, and their possible feedbacks for future land use, present a challenge for assessing and quantifying the trade-offs inherent in land use decision. This presentation develops a framework for analyzing the multiple ecosystem responses to land use change. We discuss the characteristic ecosystem responses according to stage of economic development and biophysical setting. This presentation is intended to provide a context for the other presentations in the session.
B13D-02 13:55h
Surf or Turf: How shifting from animal feed to food production could reduce nutrient loading to the Gulf of Mexico
The use of nitrogen fertilizers on croplands in central U.S. is commonly blamed for the increase in nitrogen export by the Mississippi River since the 1950s and the emergence of the large seasonal hypoxic zone in the Gulf of Mexico. The majority of production of the major Mississippi Basin crops like corn and soybean is currently used as animal feed rather than directly for human food. This study uses U.S. Department of Agriculture inventory data and nutrient cycling models to investigate how replacing the meat protein produced from Mississippi croplands with vegetable protein would affect nutrient inputs to Mississippi Basin and nitrogen loading to the Gulf of Mexico. The results show that a shift to only vegetable, dairy and some poultry production from Mississippi Basin croplands could produce the same amount of dietary protein with less than half the current land and nutrient demands. These changes would reduce the annual export of nitrate-nitrogen by the Mississippi River to a consistently low level at which hypoxic zone in the Gulf of Mexico has historically been small or non-existent.
B13D-03 14:10h
Enhancing the Conservation Value of Human-Dominated Forestlands in Hawaii
Our goal is to help make conservation economically attractive and commonplace on land that is managed largely for human enterprise. Using the Kona District of Hawaii as a case study, we plan to assess the biodiversity value, ecosystems services and economic viability of a gradient of land cover/land uses. Kona is an ideal region for such a project because as the economic viability of ranching declines, and tourism continues to rise, managers are concerned that land use will change at the expense of Hawaii's already threatened wildlife. Koa (Acacia koa) forestry is a promising land use alternative in Kona because koa is an extremely valuable hardwood that also provides valuable forest habitat. Nonetheless, many private landowners are hesitant to switch to koa forestry because of the lack of information about the benefits and costs of this land use. Our land use analysis will take place at two scales. First, we will use existing GIS and remote sensing data to assess the biodiversity and ecosystem service value of different parts of the landscape as a function of land use, land cover, and landscape context. Second, we will conduct field surveys to determine the value of each land use to three well-known but threatened taxa: forest birds, endemic drosophilid flies, and the only native land mammal, the Hawaiian hoary bat. We will integrate these results with an assessment of economic trade-offs associated with each land use option. By comparing our data on koa forests to other land uses, we also hope to identify those policy incentives for private landowners that could enable innovative conservation mechanisms like koa forestry.
B13D-04 14:25h
Land Use Change Around Nature Reserves: Implications for Sustaining Biodiversity
The effects of land use change outside of reserves on biodiversity within reserves is not well studied. This paper draws on research from Yellowstone, East Africa, Yucatan, Borneo, and Wolong, China to examine land use effects on nature reserves. Objectives are: quantify rates of change in land use around reserves; examine consequences for biodiversity within the context of specific ecological mechanisms; and draw implications for regional management. Within each of the study regions, semi-natural habitats around nature reserves have been converted to agricultural, rural residential, or urban land uses. Rates vary from 0.2-0.4 %/yr in Yucatan, to 9.5 %/yr in Borneo. Such land use changes may be important because nature reserves are often parts of larger ecosystems that are defined by flows in energy, materials, and organisms. Land use outside of reserves may disrupt these flows and alter biodiversity within reserves. Ecological mechanisms that connect biodiversity to these land use changes include habitat size, ecological flows, crucial habitats, and edge effects. For example, the effective size of the East African study area has been reduced by 45% by human activities. Based on the species area relationship, this reduction in habitat area will lead to a loss of 14% of bird and mammal species. A major conclusion is that the viability of nature reserves can best be ensured by managing them in the context of the surrounding region. Knowledge of the ecological mechanisms by which land use influences nature reserves provides design criteria for this regional management.
B13D-05 14:40h
Assessing the environmental costs and benefits of plantations under future carbon pricing scenarios
Carbon sequestration programs are gaining attention globally as a means to offset increasing fossil fuel emissions and atmospheric carbon dioxide concentrations. We are examining scenarios of C sequestration in four regions of the world: the U.S., South America, China, and Australia. The analysis uses economic models to predict where the plantations will be grown and then categorizes the other biogeochemical changes that will likely occur. The goals of the project include: 1) Evaluating the assumptions behind C sequestration programs for plantations, including the importance of rotation rates, a full accounting of carbon costs (e.g., planting and site preparation), and how the C would be stored and safeguarded. 2) Examining the scale of the process needed to make a substantial contribution to offset fossil fuel emissions (see below). The scenario we have chosen to evaluate is one that addresses the consequences of storing 1 PgC yr$^{-1}$ for 50 years. 3) Determining and summarizing the evidence for other biogeochemical changes that will likely occur. Some of the factors to be evaluated include soil acidification, changes in water fluxes and water-table dynamics, nutrient losses, changes in soil fauna and biodiversity, volatile organic carbon emissions, and erosion. 4) A final goal of the project is to make concrete recommendations for where plantations may be the most beneficial in terms of C storage and other environmental benefits, such as the amelioration of salinity and groundwater upwelling in Australia.
B13D-06 14:55h
The Geographic Variability of Contemporary United States Land Cover Change
The U.S. Geological Survey, in cooperation with NASA and the U.S. Environmental Protection Agency, is conducing a study to document the rates, causes, and consequences of 1973 to 2000 land cover change for the eighty-four ecoregions of the conterminous United States. Estimates of change are based on the interpretation of five dates of Landsat MSS and TM data (nominally 1973, 1980, 1986, 1992, and 2000). Results from an analysis of the first twenty-five ecoregions indicate that the rates, causes, and consequences of change are relative consistent within ecoregions but there are significant differences in the rates of change and types of dominant land use and land cover conversions occurring between ecoregions. For example, high rates of cyclic change are found in ecoregions dominated by resource-based economies while lower but unidirectional change is more common in more urbanized ecoregions. The specific character of change in each ecoregion is shaped by the resource potential of each ecoregion and the historical settlement patterns. Land uses changes that determine changes in cover in a given ecoregion are typically based on the highest economic use enabled by the physical environment (i.e., climate, soils, geology, landforms, etc.) and the comparative advantages associate with resource, location, and history. The differences in rates of change combined with the prevailing land use practices and enduring environmental character of different regions have a significant impact on issues such as carbon dynamics. An assessment of the ecoregion carbon dynamics also shows significant differences in flux rates over time. Overall, the results of this study show that the fabric of change across the conterminous United States highly variable in time and space and understanding the geographic dimensions of change. This suggests that ecoregions offer a framework for projecting rates, types, and the subsequent consequences of change.
B13D-07 15:10h
Exploring Global Patterns in Human Appropriation of Net Primary Production Using Earth Observation Satellites and Statistical Data
A unique combination of satellite and socio-economic data were used to explore the relationship between human consumption and the carbon cycle. Biophysical models were applied to consumption data to estimate the annual amount of Earth's terrestrial net primary production humans require for food, fiber and fuel using the same modeling architecture as satellite-supported NPP measurements. The amount of Earth's NPP required to support human activities is a powerful measure of the aggregate human impacts on the biosphere and indicator of societal vulnerability to climate change. Equations were developed estimating the amount of landscape-level NPP required to generate all the products consumed by 230 countries including; vegetal foods, meat, milk, eggs, wood, fuel-wood, paper and fiber. The amount of NPP required was calculated on a per capita basis and projected onto a global map of population to create a spatially explicit map of NPP-carbon demand in units of elemental carbon. NPP demand was compared to a map of Earth's average annual net primary production or supply created using 17 years (1982-1998) of AVHRR vegetation index to produce a geographically accurate balance sheet of terrestrial NPP-carbon supply and demand. Globally, humans consume 20 percent of Earth's total net primary production on land. Regionally the NPP-carbon balance percentage varies from 6 to over 70 percent and locally from near 0 to over 30,000 percent in major urban areas. The uneven distribution of NPP-carbon supply and demand, indicate the degree to which various human populations rely on NPP imports, are vulnerable to climate change and suggest policy options for slowing future growth in NPP demand.
B13D-08 15:25h
Global Land-Use Practices are Undermining Ecosystem Services and Human Health
Land use and land cover change are now environmental forces of global significance. Massive, worldwide changes to forests, farmlands, watersheds and air are being driven by human actions and the need to provide food, fiber, water and shelter to over six billion people. Croplands, pastures, managed forests and urban areas have all expanded in recent decades, accompanied by enormous increases in energy, water and fertilizer consumption, and dramatic losses of biodiversity. Such worldwide changes in land-use practices have enabled humans to appropriate an increasing fraction of the planet's resources, but they also undermine the capacity of ecosystems to sustain food production, maintain freshwater and forest resources, regulate climate and air quality, and ameliorate infectious diseases. We must improve our ability to assess and manage tradeoffs between meeting immediate human needs and maintaining the capacity of global ecosystems to provide goods and services in the long term.