Day: April 8, 2010

Dynamics of Range Margins for Metapopulations under Climate Change

/ Matt Artz

Proceedings of the Royal Society B: Biological Sciences, 22 April 2009, vol. 276, no. 1661, pp. 1415-1420

B.J Anderson, H.R Akçakaya, M.B Araújo, D.A Fordham, E Martinez-Meyer, W Thuiller, and B.W Brook

“We link spatially explicit climate change predictions to a dynamic metapopulation model. Predictions of species’ responses to climate change, incorporating metapopulation dynamics and elements of dispersal, allow us to explore the range margin dynamics for two lagomorphs of conservation concern. Although the lagomorphs have very different distribution patterns, shifts at the edge of the range were more pronounced than shifts in the overall metapopulation. For Romerolagus diazi (volcano rabbit), the lower elevation range limit shifted upslope by approximately 700 m. This reduced the area occupied by the metapopulation, as the mountain peak currently lacks suitable vegetation. For Lepus timidus (European mountain hare), we modelled the British metapopulation. Increasing the dispersive estimate caused the metapopulation to shift faster on the northern range margin (leading edge). By contrast, it caused the metapopulation to respond to climate change slower, rather than faster, on the southern range margin (trailing edge). The differential responses of the leading and trailing range margins and the relative sensitivity of range limits to climate change compared with that of the metapopulation centroid have important implications for where conservation monitoring should be targeted. Our study demonstrates the importance and possibility of moving from simple bioclimatic envelope models to second-generation models that incorporate both dynamic climate change and metapopulation dynamics.”

Map-projection-independent Crater Size-frequency Determination in GIS Environments – New Software Tool for ArcGIS

/ Matt Artz / 1 Comment

Planetary and Space Science, In Press, Accepted Manuscript, Available online 24 March 2010

T. Kneissl, S. van Gasselt, and G. Neukum

“Statistical analysis of crater size-frequency distributions (CSFDs) of impact craters on planetary surfaces is a well-established method to derive absolute ages on the basis of remotely-sensed image data. Although modelling approaches and the derivation of absolute ages from a given CSFD have been described and discussed in considerable depth since the late 1960s, there is no standardised methodology or guidelines for the measuring impact-crater diameters and area sizes that are both needed to determine absolute ages correctly. Distortions of distances (i.e., diameters) and areas within different map projections are considerable error sources during crater and area measurements.

“In order to address this problem and to minimize such errors, a software extension for Environmental Systems Research Institute’s (ESRI’s) ArcMap (ArcGIS) has been developed measuring CSFDs on planetary surfaces independently of image and data frame map projections, which can also be theoretically transferred to every Geographic Information System (GIS) capable of working with different map projections. Using this new approach each digitized impact crater is internally projected to a stereographic map projection with the crater’s central-point set as the projection center. In this projection, the circle is defined without any distortion of its shape (i.e., conformality). Using a sinusoidal map projection with a center longitude set to the crater’s central-point, the diameter of the impact crater is measured along this central meridian which is truescale and does not show any distortion. The crater is re-projected to the map projection of the current data frame and stored as vector geometry with attributes. Output from this workflow comprises correct impact-crater diameters and area sizes in sinusoidal map projections and can be used for further processing, i.e. absolute age determinations (e.g., using the software CraterStats). The ArcMap toolbar CraterTools developed in this context significantly helps to improve and simplify the crater size-frequency (CSF) measurement process. For GIS-based measurements, we strongly recommend our procedure as the standard method for determining CSFDs on planetary surfaces to minimize map distortion effects for further analysis.”

Trends in Shifting Cultivation and the REDD Mechanism

/ Matt Artz

Current Opinion in Environmental Sustainability, Volume 1, Issue 2, December 2009, Pages 156-160

Ole Mertz

“In many parts of the forest-agriculture frontiers of the tropics, particularly in Southeast Asia, shifting cultivation is rapidly being transformed to other land uses. Yet, there is rather limited knowledge on the spatial and demographic extent of shifting cultivation and the consequences of the transitions taking place. The proposed mechanism for reduced greenhouse gas emissions from deforestation and degradation (REDD) can be both a challenge and opportunity for shifting cultivators. Very limited literature is available on this dilemma, but a few sources point to benefits from ‘compensated reductions’ if carbon prices are sufficiently high. The main challenges will be to first ensure that poor farmers have access to the products they no longer farm, second, clarify land tenure of disputed farm and fallow land, and third, provide a guarantee that the compensations will be paid and not be lost in systems of poor governance.”

Bioenergy and Land Use: A Spatial-agent Dynamic Model of Energy Crop Production in Illinois

/ Matt Artz

International Journal of Environment and Pollution, 2009 – Vol. 39, No.1/2

Jurgen Scheffran and Todd BenDor

“To reduce dependence on foreign oil and natural gas and address concerns about climate change, the USA is increasingly developing renewable, domestic energy sources, notably biomass for the production of ethanol and biodiesel. Illinois, as one of the farming states of the Midwest, has significant potential to produce bioenergy crops. Land requirements place these crops in competition with traditional agricultural uses. To understand this interaction, this study examines the spatial and economic conditions for introducing bioenergy crops into the landscape in Illinois, which varies in soil quality and climatic conditions, and therefore in the profitability of various land uses. We use a spatial dynamic model to represent the decisions of individual farmer agents who select crops to increase their income. With this dynamic, evolutionary game approach we study the changing spatial arrangement of four key crops (corn, soybeans, miscanthus and switchgrass) which is influenced by decision rules, demands, prices, subsidies and carbon credits as well as the location of ethanol plants and transportation patterns. With a growing demand for biofuels farmers adjust their priorities towards productive bioenergy crops such as switchgrass and miscanthus which result in new land-use patterns across Illinois.”

Eradicating Rats on Lehua Island, Hawaii, with the Help of GIS and GPS

/ Matt Artz

…from the Spring 1020 issue of ArcNews…

By Justin W. Fischer and Peter Dunlevy, U.S. Department of Agriculture

“Lehua Island is an uninhabited, 290-acre crescent-shaped volcanic cone located approximately 150 miles north-northwest of Honolulu, Hawaii, or approximately 20 miles west of the island of Kauai. Lehua is a state-designated seabird sanctuary managed by the Hawaii Department of Land and Natural Resources (HIDLNR) and federally owned by the U.S. Coast Guard. Renowned for its diversity of nesting seabirds, it is home to at least 17 recorded species of seabirds, including, but not limited to, colonies of Laysan and black-footed albatross, red-footed and brown boobies, black noddies, and Newell’s shearwaters. Lehua is also home to several species of native coastal plants and insects.

“However, invasive rats are also flourishing on the island. Early biological surveys (1931) of Lehua discovered the presence of Polynesian rats. Polynesian rats are slightly smaller than their more common cousin, the Norway rat, but are still effective predators of native island flora and fauna. Rats eat a wide variety of foods, including fleshy fruits, seeds, flowers, and other plant parts and many species of insect; they also prey on birds and their eggs. Invasive rats have eliminated seabird species and suppressed or eliminated native plant and insect populations from islands around the world.”

Temporal-Spatial Analysis of Guatemala’s Religious Competition and Affiliation

/ Matt Artz

Poster by Rachel M. McCleary, Jeff Blossom, and Jose Pesina, Harvard University

“Since the late 1800’s, Protestant – particularly Evangelical and Pentecostal – churches have been competing with the once-monopolistic Roman Catholic Church. This study examines religious competition of Protestants with Roman Catholicism using data from the ledgers of the dance workshops (morerias).

“The dances in Guatemala are directly related to Roman Catholicism, for example, they are performed on a town’s saint’s day. Data in the ledgers beginning in 1900 until 2009 permit an analysis of where the dances continue to be or are no longer being performed. Using data on religious affiliation in Guatemala combined with the ledger data allows a spatial analysis of where the Evangelicals are gaining converts.

“Village and moreria locations were georeferenced using historic paper and digital maps of Guatemala. Cartographically the dance ledgers provide a very rich dataset that can be depicted by geography, time, magnitude of dances, and directionally by dance sites and morerias. The background for the maps is a shaded relief image made from a digital elevation model intended to depict the rugged and varying terrain of Guatemala.”

The Spatial and Temporal Variability of Groundwater Recharge in a Forested Basin in Northern Wisconsin

/ Matt Artz

Hydrological Processes, Volume 24, Issue 4, Date: 15 February 2010, Pages: 383-392

W. R. Dripps, K. R. Bradbury

“Recharge varies spatially and temporally as it depends on a wide variety of factors (e.g. vegetation, precipitation, climate, topography, geology, and soil type), making it one of the most difficult, complex, and uncertain hydrologic parameters to quantify. Despite its inherent variability, groundwater modellers, planners, and policy makers often ignore recharge variability and assume a single average recharge value for an entire watershed. Relatively few attempts have been made to quantify or incorporate spatial and temporal recharge variability into water resource planning or groundwater modelling efforts. In this study, a simple, daily soil-water balance model was developed and used to estimate the spatial and temporal distribution of groundwater recharge of the Trout Lake basin of northern Wisconsin for 1996-2000 as a means to quantify recharge variability. For the 5 years of study, annual recharge varied spatially by as much as 18 cm across the basin; vegetation was the predominant control on this variability. Recharge also varied temporally with a threefold annual difference over the 5-year period. Intra-annually, recharge was limited to a few isolated events each year and exhibited a distinct seasonal pattern. The results suggest that ignoring recharge variability may not only be inappropriate, but also, depending on the application, may invalidate model results and predictions for regional and local water budget calculations, water resource management, nutrient cycling, and contaminant transport studies. Recharge is spatially and temporally variable, and should be modelled as such.”