Myrna Hall

Modeled Climate-Induced Glacier Change in Glacier National Park, 1850–2100

Abstract The glaciers in the Blackfoot–Jackson Glacier Basin of Glacier National Park, Montana, decreased in area from 21.6 square kilometers (km2) in 1850 to 7.4 km2 in 1979. Over this same period global temperatures increased by 0.45°C (± 0.15°C). We analyzed the climatic causes and ecological consequences of glacier retreat by creating spatially explicit models of the creation and ablation of glaciers and of the response of vegetation to climate change. We determined the melt rate and spatial distribution of glaciers under two possible future climate scenarios, one based on carbon dioxide–induced global warming and the other on a linear temperature extrapolation. Under the former scenario, all glaciers in the basin will disappear by the year 2030, despite predicted increases in precipitation; under the latter, melting is slower. Using a second model, we analyzed vegetation responses to variations in soil moisture and increasing temperature in a complex alpine landscape and predicted where plant communities are likely to be located as conditions change.

Spatial dependence and the relationship of soil organic carbon and soil moisture in the Luquillo Experimental Forest, Puerto Rico

We used geo-spatial statistical techniques to examine the spatial variation and relationship of soil organic carbon (SOC) and soil moisture (SM) in the Luquillo Experimental Forest (LEF), Puerto Rico, in order to test the hypothesis that mountainous terrain introduces spatial autocorrelation and crosscorrelation in ecosystem and soil properties. Soil samples (n = 100) were collected from the LEF in the summer of 1998 and analyzed for SOC, SM, and bulk density (BD). A global positioning system was used to georeference the location of each sampling site. At each site, elevation, slope and aspect were recorded. We calculated the isotropic and anisotropic semivariograms of soil and topographic properties, as well as the cross-variograms between SOC and SM, and between SOC and elevation. Then we used four models (random, linear, spherical and wave/hole) to test the semi-variances of SOC, SM, BD, elevation, slope and aspect for spatial dependence. Our results indicate that all the studied properties except slope angle exhibit spatial dependence within the scale of sampling (200 – 1000 m sampling interval). The spatially structured variance (the variance due to the location of sampling sites) accounted for a large proportion of the sample variance for elevation (99%), BD (90%), SOC (68%), aspect (56%) and SM (44%). The ranges of spatial dependence (the distances within which parameters are spatially dependent) for aspect, SOC, elevation, SM, and BD were 9810 m, 3070 m, 1120 m, 930 m and 430 m, respectively. Cross correlograms indicate that SOC varies closely with elevation and SM depending on the distances between samples. The correlation can shift from positive to negative as the separation distance increases. Larger ranges of spatial dependence of SOC, aspect and elevation indicate that the distribution of SOC in the LEF is determined by a combination of biotic (e.g., litterfall) and abiotic factors (e.g., microclimate and topographic features) related to elevation and aspect. This demonstrates the importance of both elevation and topographic gradients in controlling climate, vegetation distribution and soil properties as well as the associated biogeochemical processes in the LEF.

The efficiency of land and energy use in tropical economies and agriculture

Abstract Technological optimism about economic processes, and especially the food production required to feed the worlds growing population, must be tempered severely by constraints caused by limited land and fossil energy availability. We examine this hypothesis explicitly using several empirical assessments and several computer models, one of which was specifically designed to convey complex information to a non-technical population. We use data from various countries for our analyses but present more detail for Costa Rica. Our analyses find little support for the idea that development can take place without commensurate energy investments. We also extrapolate through the Year 2050 to project the amount of land and fossil energy that would be required to meet Costa Rican food demand, under a range of assumptions about population growth rates, land distribution, national food self-sufficiency, fertilizer availability, erosion rates and relative prices of coffee and fertilizer. Our results suggest that during the first quarter to half of the next century, it will be increasingly difficult, and eventually impossible, to feed qugrowing Costa Rican population no matter what (realistic) assumptions are made. The most important variables are the price of fertilizer exports and whether land is used principally for domestic crops or for export crops that traded for food.

An integrated monitoring/modeling framework for assessing human-nature interactions in urbanizing watersheds: Wappinger and Onondaga Creek watersheds, New York, USA

In much of the world, rapidly expanding areas of impervious surfaces due to urbanization threaten water resources. Although tools for modeling and projecting land use change and water quantity and quality exist independently, to date it is rare to find an integrated, comprehensive modeling toolkit to readily assess the future course of urban sprawl, and the uncertainties of its impact on watershed ecosystem health. We have developed a combined socio-economic-ecological toolbox, running on the ArcGIS platform, to analyze subsequent impacts on streamflow and nutrient export using the spatial pattern of urbanization in response to anticipated socio-economic conditions and scenarios. We have applied our toolbox to two New York State catchment areas, Onondaga Creek watershed and Wappinger Creek, that have undergone rapid development in the last decades. Uncertainties in temporal trends of new housing permits, spatial distribution of development detection and development potential, and stream conditions were evaluated using three separate toolsets (ArcECON, ArcGEOMOD, and ArcGWLF, respectively). The toolbox capabilities are demonstrated through a year 2020 scenario prediction and analysis, where the aforementioned tools were explicitly linked to determine future housing development, spread of impervious areas, runoff generation, and stream nitrate flux. Higher economic growth was estimated to induce increased new housing permits and spread of impervious surface areas, leading to flashier streamflow as well as worsening stream condition, which was aggravated when only the forest lands were allowed to be developed.

Scenario Analysis of Economy–Ecology Interactions in the Hudson River Basin

Our primary goal is to develop an integrated, quantitative assessment tool evaluating how human economic activities influence spatial patterns of urbanization, and how land-use change resulting from urbanization affects stream water quality and aquatic ecosystem health. Here we present a prototype of a holistic assessment tool composed of three “building blocks” simulating the social and economic structures, spatial pattern of urbanization, and watershed health as determined by various metrics. The assessment tool is applied to Dutchess County, New York and two of its largest watersheds, Wappinger and Fishkill Creek watersheds, demonstrating how an explicit link can be established between human economic activities and ecosystem health through changes in land use.