ICC Programming

Mapping landscapes

7110.1 - Scale Matters: Identifying the Effects of Landscape Fragmentation on Land Loss

Friday, July 7
8:30 AM - 8:50 AM
Location: Coolidge

In spatial analysis, the scale effects matter. Scale in the cartography and GIS literature has four meanings: the spatial extent of a study, the data or image resolution, the spatial extent of a spatial process, and the representation through a map. These four meanings can be applied both spatially and temporally. It has been documented widely that scale effects contribute to the uncertainty of research findings, making interpretations of the findings and conclusions about a pattern and its underlying processes difficult. Hence, it is advisable to include a multiple-scale analysis for any studies to reduce the uncertainties of the results. However, such practice is not commonly adopted due to many reasons, including the lack of quality data or the lack of awareness of the scale effects. This paper demonstrates the need for and the benefits from conducting a multiple-scale analysis through a recent study that examines the effects of landscape fragmentation on land loss in coastal Louisiana. The study conducted at different scales yields results that have important theoretical and practical implications.

Coastal Louisiana has been facing a serious land loss problem over the past several decades. Coastal land loss is usually a result of complex natural and human factors interacting such as lack of sediment supply, land subsidence, and sea-level rise. However, the importance of landscape fragmentation on land loss has seldom been examined. This study evaluates the effects of landscape fragmentation on land loss in the Lower Mississippi River Basin region. The hypothesis is that the higher the degree of landscape fragmentation, the greater the amount of land loss in the next time period. Landsat-TM data with a pixel size of 30m x 30m in 1996 and 2010 were used, and fractal dimension and Moran’s I spatial autocorrelation statistics were calculated to represent the degree of fragmentation. To isolate the effect of fragmentation so that it can be better evaluated, only sample boxes with a 50-percent land-water ratio were used. Then regression analyses between fragmentation indices and land loss percentage in the next time period were conducted. At first, 100 samples with the box size of 101x101 pixels was used, which did not yield significant correlation between fragmentation and land loss. Then, three other sample box sizes, including sizes of 71x71, 51x51, and 31x31 pixels, were used to examine the scale and context effects. For each box size, 100 samples were randomly selected. The regression results show that the R-square values for box sizes of 71x71, 51x51 and 31x31 are all statistically significant (0.20, 0.45, 0.35; p < 0.001), with the highest R-square value occurred when box size is 51x51.

These results suggest that landscape fragmentation affects land loss, and land fragmentation alone can account for as much as 45% of land loss in the next time period. Hence, land protection might be most effective by prioritizing areas with land patches that have the least fragmentation. Furthermore, the scale at which the R-square value is the highest indicates the scale at which the effects are most likely to be observed (51x51 box size, approximately 1.5x1.5 km-square, R-square = 0.45), which might indicate that future land loss modeling using this neighborhood scale would be most effective.

Nina S.N Lam

Professor
Louisiana State University

Nina Lam is Professor and E.L. Abraham Distinguished Professor in the Department of Environmental Sciences at Louisiana State University. She was Chair of the Department (2007-2010), Program Director of U.S. National Science Foundation Geography and Spatial Sciences Program (1999-2001), and President of University Consortium on Geographic Information Science (UCGIS, 2004). Professor Lam’s research interests are in GIS, remote sensing, spatial analysis, environmental health, and community resilience. She has published on topics including spatial interpolation, fractals, cancer mortality, scale and uncertainties, AIDS in America, business recovery in New Orleans after Katrina, community resilience assessment, coastal resilience modeling using a coupled natural-human system approach. Lam has received top awards from within LSU (Distinguished Faculty, Rainmaker, Distinguished Research Master, and Outstanding Faculty Research Award), and outside LSU including Association of American Geographers’ (AAG) (Outstanding Contributions in Remote Sensing) and University Consortium on Geographic Information Science (UCGIS Fellow, The 2016 Inaugural Carolyn Merry Mentoring Award). Lam has coedited two books and authored and co-authored over 95 refereed articles. She has served as the Principal Investigor or Co-Principal Investigator of over 40 external grants. Lam has advised 5 post-doctoral associates, 17 PhDs, and 30 M.S. students.

Presentation(s):

Send Email for Nina Lam

Weijia Cheng

Louisiana State University

MS Graduate, Department of Environmental Sciences, LSU

Presentation(s):

Send Email for Weijia Cheng

Nina S.N Lam

Professor
Louisiana State University

Nina Lam is Professor and E.L. Abraham Distinguished Professor in the Department of Environmental Sciences at Louisiana State University. She was Chair of the Department (2007-2010), Program Director of U.S. National Science Foundation Geography and Spatial Sciences Program (1999-2001), and President of University Consortium on Geographic Information Science (UCGIS, 2004). Professor Lam’s research interests are in GIS, remote sensing, spatial analysis, environmental health, and community resilience. She has published on topics including spatial interpolation, fractals, cancer mortality, scale and uncertainties, AIDS in America, business recovery in New Orleans after Katrina, community resilience assessment, coastal resilience modeling using a coupled natural-human system approach. Lam has received top awards from within LSU (Distinguished Faculty, Rainmaker, Distinguished Research Master, and Outstanding Faculty Research Award), and outside LSU including Association of American Geographers’ (AAG) (Outstanding Contributions in Remote Sensing) and University Consortium on Geographic Information Science (UCGIS Fellow, The 2016 Inaugural Carolyn Merry Mentoring Award). Lam has coedited two books and authored and co-authored over 95 refereed articles. She has served as the Principal Investigor or Co-Principal Investigator of over 40 external grants. Lam has advised 5 post-doctoral associates, 17 PhDs, and 30 M.S. students.

Presentation(s):

Send Email for Nina Lam


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