PUTTING A CART BEFORE THE SEARCH: SUCCESSFUL HABITAT PREDICTION FOR A RARE FOREST HERB

The realms of rare species conservation and metapopulation biology theory are often interrelated, and hence share several basic challenges. Two of the most important are the critical and frequently difficult tasks of distinguishing a priori between habitat and nonhabitat, and then delimiting suitable habitat patches in a study area. We combined classification tree analysis, a subset of classification and regression tree (CART) modeling, with digital data layers of environmental variables in a geographic information system (GIS) to predict suitable habitat and potential new population occurrences for turkeybeard (Xerophyllum asphodeloides), a rare liliaceous understory herb associated with southern Appalachian pine-oak (Pinus-Quercus) forests, in northwestern Virginia. Sample values from eight environmental data layers and population survey data were used in the modeling process to produce a cross-validated classification tree that predicted suitable habitat in the study area. Elevation, slope, forest type, and fire frequency were the four main explanatory variables in the model. Approximately 4% of the study area was classified into five suitable habitat classes, with a misclassification error rate of 4.74%. The final 13-leaf tree correctly classified 74% of the known presence areas and 90% of the known absence areas, and ground-truthing surveys resulted in the discovery of eight new occupied habitat patches. Results of this study are important for conservation and management of X. asphodeloides, as well as for the applicability of the habitat modeling techniques to enhancing the study of metapopulations and disturbance regimes in Appalachian forests. In addition, they con- firm the potential and value of CART and GIS-based modeling approaches to species distribution problems. Our model was successful at defining suitable habitat and discovering new populations of a rare species at the landscape scale. Similar application to other rare species could prove very useful for addressing these and other ecological and conservation issues, such as planning transplantation or reintroduction experiments, identifying meta- population fragmentation thresholds, and formulating conservation strategies.

[1]  A. Prasad,et al.  PREDICTING ABUNDANCE OF 80 TREE SPECIES FOLLOWING CLIMATE CHANGE IN THE EASTERN UNITED STATES , 1998 .

[2]  C. Thomas.  Extinction, colonization, and metapopulations: environmental tracking by rare species , 1994 .

[3]  Roger Woodard,et al.  Interpolation of Spatial Data: Some Theory for Kriging , 1999, Technometrics.

[4]  L. S. Barden,et al.  Effects of Fire on Pine and Pine-Hardwood Forests in the Southern Appalachians , 1976 .

[5]  B. Husband,et al.  A METAPOPULATION PERSPECTIVE IN PLANT POPULATION BIOLOGY , 1996 .

[6]  David L. Verbyla,et al.  Classification and Regression Tree Analysis for Assessing Hazard of Pine Mortality Caused by Heterobasidion annosum , 1993 .

[7]  J. Michaelsen,et al.  Regression Tree Analysis of satellite and terrain data to guide vegetation sampling and surveys , 1994 .

[8]  P. Lesica.  Autecology of the Endangered Plant Howellia Aquatilis; Implications for Management and Reserve Design. , 1992, Ecological applications : a publication of the Ecological Society of America.

[9]  M. Harmon.  Fire History of the Westernmost Portion of Great Smoky Mountains National Park , 1982 .

[10]  Leo Breiman,et al.  Classification and Regression Trees , 1984 .

[11]  H. Delcourt,et al.  Pre‐Columbian Native American Use of Fire on Southern Appalachian Landscapes , 1997 .

[12]  R. Plant,et al.  Classification trees: An alternative non‐parametric approach for predicting species distributions , 2000 .

[13]  N. Curtis.  A Post-fire Ecological Study of Xanthorrhoea australis Following Prescribed Burning in the Warby Range State Park, North-eastern Victoria, Australia , 1998 .

[14]  R. Freckleton,et al.  Large‐scale spatial dynamics of plants: metapopulations, regional ensembles and patchy populations , 2002 .

[15]  Marc D. Abrams,et al.  Fire and the Development of Oak Forests , 1992 .

[16]  Ilkka Hanski,et al.  Metapopulation Dynamics: From Concepts and Observations to Predictive Models , 1997 .

[17]  S. DeGloria,et al.  Error assessment in decision-tree models applied to vegetation analysis , 1995, Landscape Ecology.

[18]  Bart R. Johnson,et al.  Genetic Diversity and Population Size in Four Rare Southern Appalachian Plant Species , 1996 .

[19]  C. Woodhouse,et al.  Two centuries of fire in a southwestern Virginia Pinus pungens community , 1995 .

[20]  Helen T. Murphy,et al.  Context and connectivity in plant metapopulations and landscape mosaics: does the matrix matter? , 2004 .

[21]  C. T. Dyrness,et al.  Natural Vegetation of Oregon and Washington , 1988 .

[22]  Dean L. Urban,et al.  Focal Species, Community Representation, and Physical Proxies as Conservation Strategies: a Case Study in the Amphibolite Mountains, North Carolina, U.S.A. , 2002 .

[23]  Robert H. Whittaker,et al.  Vegetation of the Great Smoky Mountains , 1956 .

[24]  Arthur Cronquist,et al.  Flora of the Pacific Northwest , 1974 .

[25]  D. Cleland,et al.  Determining the Spatial Extent of Historical Fires With Geostatistics in Northern Lower Michigan , 2003 .

[26]  M. Abrams.  Fire and the Ecological History of Oak Forests in the Eastern United States , 2000 .

[27]  飯塚 寛,et al.  Aspect transformation in site productivity research , 1967 .

[28]  J. Michaelsen,et al.  Interactions of Factors Affecting Seedling Recruitment of Blue Oak (Quercus Douglasii) in California , 1989 .

[29]  E. Menges,et al.  POPULATION VIABILITY WITH FIRE IN ERYNGIUM CUNEIFOLIUM: DECIPHERING A DECADE OF DEMOGRAPHIC DATA , 2004 .

[30]  B. Lees,et al.  A new method for predicting vegetation distributions using decision tree analysis in a geographic information system , 1991 .

[31]  Michael Edward Hohn,et al.  An Introduction to Applied Geostatistics: by Edward H. Isaaks and R. Mohan Srivastava, 1989, Oxford University Press, New York, 561 p., ISBN 0-19-505012-6, ISBN 0-19-505013-4 (paperback), $55.00 cloth, $35.00 paper (US) , 1991 .

[32]  M. Abrams.  Where Has All the White Oak Gone? , 2003 .

[33]  B. W. Wilgen,et al.  Fire and Plants , 1995, Population and Community Biology Series.

[34]  P. Bernhardt,et al.  Pollination and seed production in Xerophyllum tenax (Melanthiaceae) in the Cascade Range of central Oregon. , 2004, American journal of botany.

[35]  M. Cruzan.  POPULATION SIZE AND FRAGMENTATION THRESHOLDS FOR THE MAINTENANCE OF GENETIC DIVERSITY IN THE HERBACEOUS ENDEMIC SCUTELLARIA MONTANA (LAMIACEAE) , 2001, Evolution; international journal of organic evolution.

[36]  Brian G. Lees,et al.  Decision-tree and rule-induction approach to integration of remotely sensed and GIS data in mapping vegetation in disturbed or hilly environments , 1991 .

[37]  David L. Verbyla,et al.  Classification trees: a new discrimination tool , 1987 .

[38]  G. De’ath,et al.  CLASSIFICATION AND REGRESSION TREES: A POWERFUL YET SIMPLE TECHNIQUE FOR ECOLOGICAL DATA ANALYSIS , 2000 .

[39]  James H. Brown,et al.  The Influence of Geomorphological Heterogeneity on Biodiversity  II. A Landscape Perspective , 1998 .

[40]  P. White,et al.  Changes in Xeric Forests in Western Great Smoky Mountains National Park, 1936-1995 , 1998 .

[41]  E. Komarek.  8 – Effects of Fire on Temperate Forests and Related Ecosystems: Southeastern United States , 1974 .

[42]  W. C. Johnson,et al.  Age structure and the maintenance of Pinus pungens in pine-oak forests of southwestern Virginia. , 1990 .

[43]  J. Agee,et al.  FIRE FREQUENCY IN THE INTERIOR COLUMBIA RIVER BASIN: BUILDING REGIONAL MODELS FROM FIRE HISTORY DATA , 2000 .

[44]  S. Bratton,et al.  Genetic Diversity in a Threatened Wetland Species, Helonias bullata (Liliaceae) , 1995 .

[45]  Andrew D. Taylor,et al.  Empirical Evidence for Metapopulation Dynamics , 1997 .

[46]  M. Abrams,et al.  A 400-year history of fire and oak recruitment in an old-growth oak forest in western Maryland, U.S.A. , 2001 .

[47]  E. Menges,et al.  A Fire‐Explicit Population Viability Analysis of Hypericum cumulicola in Florida Rosemary Scrub , 2003 .

[48]  B. E. Giles,et al.  A Case Study of Genetic Structure in a Plant Metapopulation , 1997 .

[49]  D. Zobel.  Factors Affecting the Distribution of Pinus pungens, an Appalachian Endemic , 1969 .

[50]  W. M. Whitten,et al.  Generic circumscription and relationships in the tribe Melanthieae (Liliales, Melanthiaceae), with emphasis on Zigadenus: evidence from ITS and trnL-F sequence data. , 2001, American journal of botany.