Modeling spatially explicit forest structural attributes using Generalized Additive Models

We modelled forest composition and structural diversity in the Uinta Mountains, Utah, as functions of satellite spectral data and spatially-explicit environmental variables through generalized additive models. Measures of vegetation composition and structural diversity were available from existing forest inventory data. Satellite data included raw spectral data from the Landsat Thematic Mapper (TM), a GAP Analysis classified TM, and a vegetation index based on raw spectral data from an advanced very high resolution radiometer (AVHRR). Environmental predictor variables included maps of temperature, precipitation, elevation, aspect, slope, and geology. Spatially-explicit predictions were generated for the presence of forest and lodgepole cover types, basal area of forest trees, percent cover of shrubs, and density of snags. The maps were validated using an independent set of field data collected from the Evanston ranger district within the Uinta Mountains. Within the Evanston ranger district, model predictions were 88% and 80% accurate for forest presence and lodgepole pine (Pinus contorta), respectively. An average 62% of the predictions of basal area, shrub cover, and snag density fell within a 15% deviation from the field validation values. The addition of TM spectral data and the GAP Analysis TM-classified data contributed significantly to the models' predictions, while AVHRR had less significance.

[1]  A. O. Nicholls,et al.  Measurement of the realized qualitative niche: environmental niches of five Eucalyptus species , 1990 .

[2]  Alan H. Strahler,et al.  Forest Classification and Inventory System using Landsat, digital terrain, and ground sample data , 1979 .

[3]  H. Akaike,et al.  Information Theory and an Extension of the Maximum Likelihood Principle , 1973 .

[4]  Russell G. Congalton,et al.  Using thematic mapper imagery to examine forest understory , 1990 .

[5]  F. J. Ahern,et al.  Forestry information content of Thematic Mapper data , 1986 .

[6]  Trevor Hastie,et al.  Statistical Models in S , 1991 .

[7]  N. Cressie,et al.  Statistics for Spatial Data. , 1992 .

[8]  Janet Franklin,et al.  Thematic mapper analysis of coniferous forest structure and composition , 1986 .

[9]  M. Austin,et al.  The Problem of Non-Linearity in Ordination: Experiments with Two-Gradient Models , 1971 .

[10]  Jacob Cohen.  A Coefficient of Agreement for Nominal Scales , 1960 .

[11]  T. Yee,et al.  Generalized additive models in plant ecology , 1991 .

[12]  P. Holmgren,et al.  Intermountain flora. Vascular plants of the Intermountain West, U.S.A. Volume six. The monocotyledons. , 1978 .

[13]  Chris Margules,et al.  Patterns in the distributions of species and the selection of nature reserves: An example from Eucalyptus forests in South-eastern New South Wales , 1989 .

[14]  J. R. Koehler,et al.  Modern Applied Statistics with S-Plus. , 1996 .

[15]  Robert Haining,et al.  Statistics for spatial data: by Noel Cressie, 1991, John Wiley & Sons, New York, 900 p., ISBN 0-471-84336-9, US $89.95 , 1993 .

[16]  Anne Lohrli.  Chapman and Hall , 1985 .

[17]  M. Austin,et al.  Current approaches to modelling the environmental niche of eucalypts: implication for management of forest biodiversity , 1996 .

[18]  C. Daly,et al.  A Statistical-Topographic Model for Mapping Climatological Precipitation over Mountainous Terrain , 1994 .

[19]  J. Leathwick,et al.  Forest pattern, climate and vulcanism in central North Island, New Zealand , 1992 .

[20]  Mike P. Austin,et al.  Continuum Concept, Ordination Methods, and Niche Theory , 1985 .

[21]  D. Richard Cutler,et al.  Assessing map accuracy in a remotely sensed, ecoregion-scale cover map , 1998 .

[22]  A. O. Nicholls,et al.  Determining species response functions to an environmental gradient by means of a β‐function , 1994 .

[23]  Thomas C. Edwards,et al.  Use of generalized linear models and digital data in a Forest Inventory of Northern Utah , 1999 .

[24]  T. Frank.  Mapping dominant vegetation communities in the Colorado Rocky Mountain Front Range with Landsat Thematic Mapper and digital terrain data , 1988 .

[25]  R. D. Ramsey,et al.  Landscape Cover-Type Modeling Using a Multi-Scene Thematic Mapper Mosaic , 1997 .

[26]  T. Frescino.  Development and Validation of Forest Habitat Models in the Uinta Mountains, Utah , 1998 .

[27]  D. H. Knight,et al.  Aims and Methods of Vegetation Ecology , 1974 .

[28]  Jesslyn F. Brown,et al.  Development of a land-cover characteristics database for the conterminous U.S. , 1991 .

[29]  M. Barbour,et al.  Terrestrial Plant Ecology , 1981 .

[30]  L. Swift,et al.  Algorithm for solar radiation on mountain slopes , 1976 .

[31]  J. Henderson,et al.  Coniferous forest habitat types of northern Utah. , 1984 .