Spatial and covariate-varying relationships among dominant tree species in Utah
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Spatial and covariate-varying relationships among dominant tree species in Utah Matthew J. Heaton1 · Candace Berrett1 · R. Justin DeRose2 · Matthew F. Bekker3 Received: 1 January 2020 / Revised: 7 July 2020 / Accepted: 15 July 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract The presence and establishment of a tree species at a particular spatial location is influenced by multiple physiological and environmental filters such as propagule pressure (seed availability), light and moisture availability, and slope and elevation. However, a less understood environmental filter to species-specific establishment is competition or facilitation between dominant tree species. For example, certain tree species may compete for resources at spatial locations where such resources are scarce while less competition may occur at resource-rich areas. Using data from the Forest Inventory and Analysis (FIA) program of the United States Department of Agriculture (USDA) Forest Service, we develop a multivariate spatial Bernoulli model to investigate the space-varying relationship between extant tree species in Utah. Additionally, we propose a novel modeling strategy that explains the spatially varying relationships by regressing the associated between-species correlation matrix on available covariate data. Positive definite conditions of the covariate-varying correlation matrix are ensured by defining the regression in terms of the unique partial correlation matrix. Results indicate that correlations between species are dependent upon elevation.
Handling Editor: Pierre Dutilleul.
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Matthew F. Bekker [email protected] Matthew J. Heaton [email protected] Candace Berrett [email protected] R. Justin DeRose [email protected]
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Department of Statistics, Brigham Young University, 223 TMCB, Provo, UT 84602, USA
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Department of Wildland Resources and Ecology Center, Utah State University, Logan, UT 84322, USA
3
Department of Geography, Brigham Young University, 672C KMBL, Provo, UT 84602, USA
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Environmental and Ecological Statistics
Keywords Multivariate Bernoulli · Partial correlation matrix · Spatial basis function
1 Introduction Whether a particular tree species becomes established and persists on a given site can be understood in terms of multiple physiological and environmental phenomena. In the semi-arid interior of the western United States (i.e., Great Basin and central and southern Rocky Mountains), the establishment of a tree species in a location is strongly influenced by mountains in that mountains dictate microclimate. That is, the presence, juxtaposition, height, and orientation of mountains directly influence the amount and type of precipitation which, in turn, controls moisture available to trees and vegetation. However, just as unforested valleys may not be uniformly unsuitable for trees (Kupfer et al. 2006), mountain environments themselves are heterogeneous, providing a range of potentially suitable habitats across interacting gradients of elevation and topogra
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