John Tirpak | Fordham University (original) (raw)
Papers by John Tirpak
Journal of Wildlife Management, 2007
... Mechanistic Home Range Analysis, by Paul R. Moorcroft and Mark A. Lewis. 2006. John M. Tirpak... more ... Mechanistic Home Range Analysis, by Paul R. Moorcroft and Mark A. Lewis. 2006. John M. Tirpak. ...Tirpak, JM (2007), Mechanistic Home Range Analysis, by Paul R. Moorcroft and Mark A. Lewis. 2006. The Journal of Wildlife Management, 71: 24442445. doi: 10.2193/2007-147. ...
Forest Ecology and Management - FOREST ECOL MANAGE, 2010
Like many similar forest species, ruffed grouse (Bonasa umbellus; hereafter grouse) populations i... more Like many similar forest species, ruffed grouse (Bonasa umbellus; hereafter grouse) populations in the central and southern Appalachians (CSA) are strongly affected by forest composition at the landscape scale. Because these populations are in decline, managers require accurate forest maps to understand how stand level characteristics affect the survival and reproductive potentials of individual birds to design management strategies that improve grouse abundance. However, traditional mapping techniques are often labor-intensive and cost-prohibitive. We used a normalized difference vegetation index (NDVI) from each of 8 Landsat images and the digital elevation model (DEM)-derived variables of elevation and aspect in discriminant analyses to classify 7 study areas to 3 overstory classes (evergreen, hardwoods, and oak) and distinguish evergreen and deciduous understories in the CSA, 2000-2002. Overall accuracy was 82.08%, varying from 83.59% for oak to 79.79% for hardwoods overstories. Periods with large phenological differences among classes, particularly early and late spring, were most useful for discriminating overstory vegetation types. Alternatively, winter NDVI in combination with elevation was critical for differentiating evergreen and deciduous understories. Multitemporal image sets used in concert with DEMs provided a cost-effective alternative to hyperspectral sensors for improving wildlife habitat classification accuracy with Landsat imagery. This allowed for enhanced understanding of grouse-habitat relationships and habitat affects on grouse populations that allowed for improved management. With the incorporation of simple adjustments for local forest plant species phenology into the model, it may be used to better classify wildlife habitat of similar species in areas with comparable forest communities and topography. Multitemporal images can also be used to differentiate grassland communities, monitor wetlands, and serve as baseline data for detecting changes in land use over longer temporal scales, making their use in forest wildlife habitat studies cost-justifiable.
Forest Ecology and Management, 2006
Eastern hemlock (Tsuga canadensis; hereafter hemlock) was once relatively common in the northeast... more Eastern hemlock (Tsuga canadensis; hereafter hemlock) was once relatively common in the northeastern United States. However, recent disturbances -including exotic pests and white-tailed deer overpopulation -have exacerbated declines in hemlock forest in the 20th century. As a previously undisturbed stand, the Mianus River Gorge Preserve (MRGP) provided an ideal site to investigate the potential impact of these factors on the structure and composition of old-growth hemlock forests. The woody vegetation of this forest was first surveyed in 1965 and then again in 2004. The overstory tree community was similar between the two time periods with hemlock dominant in both samples. Conversely, seedlings, saplings, and transgressives exhibited sharp declines in most species, including hemlock, which resulted in dissimilar community composition and structure for these age classes between 1965 and 2004. Despite relative continuity in the dominance of mature hemlocks, low recruitment due to overbrowsing makes the long-term persistence of hemlock in the old-growth forest of MRGP tenuous. #
Journal of Wildlife Management, 2007
... Mechanistic Home Range Analysis, by Paul R. Moorcroft and Mark A. Lewis. 2006. John M. Tirpak... more ... Mechanistic Home Range Analysis, by Paul R. Moorcroft and Mark A. Lewis. 2006. John M. Tirpak. ...Tirpak, JM (2007), Mechanistic Home Range Analysis, by Paul R. Moorcroft and Mark A. Lewis. 2006. The Journal of Wildlife Management, 71: 24442445. doi: 10.2193/2007-147. ...
Canadian Journal of Zoology, 2008
Declines in ruffed grouse (Bonasa umbellus (L., 1766)) populations in the central and southern Ap... more Declines in ruffed grouse (Bonasa umbellus (L., 1766)) populations in the central and southern Appalachians may be linked to low brood survival. Therefore, managing for high-quality brood habitat could improve grouse numbers. Understanding how brood habitat ...
Forest Ecology and Management - FOREST ECOL MANAGE, 2010
Like many similar forest species, ruffed grouse (Bonasa umbellus; hereafter grouse) populations i... more Like many similar forest species, ruffed grouse (Bonasa umbellus; hereafter grouse) populations in the central and southern Appalachians (CSA) are strongly affected by forest composition at the landscape scale. Because these populations are in decline, managers require accurate forest maps to understand how stand level characteristics affect the survival and reproductive potentials of individual birds to design management strategies that improve grouse abundance. However, traditional mapping techniques are often labor-intensive and cost-prohibitive. We used a normalized difference vegetation index (NDVI) from each of 8 Landsat images and the digital elevation model (DEM)-derived variables of elevation and aspect in discriminant analyses to classify 7 study areas to 3 overstory classes (evergreen, hardwoods, and oak) and distinguish evergreen and deciduous understories in the CSA, 2000-2002. Overall accuracy was 82.08%, varying from 83.59% for oak to 79.79% for hardwoods overstories. Periods with large phenological differences among classes, particularly early and late spring, were most useful for discriminating overstory vegetation types. Alternatively, winter NDVI in combination with elevation was critical for differentiating evergreen and deciduous understories. Multitemporal image sets used in concert with DEMs provided a cost-effective alternative to hyperspectral sensors for improving wildlife habitat classification accuracy with Landsat imagery. This allowed for enhanced understanding of grouse-habitat relationships and habitat affects on grouse populations that allowed for improved management. With the incorporation of simple adjustments for local forest plant species phenology into the model, it may be used to better classify wildlife habitat of similar species in areas with comparable forest communities and topography. Multitemporal images can also be used to differentiate grassland communities, monitor wetlands, and serve as baseline data for detecting changes in land use over longer temporal scales, making their use in forest wildlife habitat studies cost-justifiable.
Forest Ecology and …, 2010
Ruffed grouse (Bonasa umbellus; hereafter grouse) populations in the central and southern Appalac... more Ruffed grouse (Bonasa umbellus; hereafter grouse) populations in the central and southern Appalachians (CSA) are declining due to widespread maturation of forest cover. Effective management of this species requires a sex-and age-specific understanding of habitat preferences at multiple temporal and spatial scales. We used multivariate logistic regression models to compare habitat within 1440 grouse home ranges and 1400 equally sized buffered random points across 7 CSA study areas. On most sites, grouse home ranges were positively associated with roads and young forest (<20 years old). Sex and age status affected habitat preference. In general, males used younger forest than females, likely because of differences in habitat use during reproductive periods. Juveniles had fewer vegetation types preferred by adult grouse and more of the avoided vegetation types within their home ranges, indicative of competitive exclusion. Adult females had the greatest specificity and selectivity of habitat conditions within their home ranges. Habitat selection varied among seasons and years on most sites. Winter habitat use reflected behavior that maximized energy conservation, with open vegetation types avoided in the winter on the northernmost study areas, and topography important on all areas. Summer habitat selection reflected vegetation types associated with reproductive activities. Scale influenced habitat preference as well. Although roads and forest age predominantly influenced grouse home range location within the landscape, mesic forest types were most important in determining core area use within the home range. This was likely a result of increased food availability and favorable microclimate. Habitat management efforts should attempt to maintain ∼3-4% of the landscape in young forest cover (<20 years old), evenly distributed across management areas. Roads into these areas should be seeded as appropriate to enhance brood habitat and provide travel corridors connecting suitable forest stands.
Forest Ecology and Management, 2006
Eastern hemlock (Tsuga canadensis; hereafter hemlock) was once relatively common in the northeast... more Eastern hemlock (Tsuga canadensis; hereafter hemlock) was once relatively common in the northeastern United States. However, recent disturbances -including exotic pests and white-tailed deer overpopulation -have exacerbated declines in hemlock forest in the 20th century. As a previously undisturbed stand, the Mianus River Gorge Preserve (MRGP) provided an ideal site to investigate the potential impact of these factors on the structure and composition of old-growth hemlock forests. The woody vegetation of this forest was first surveyed in 1965 and then again in 2004. The overstory tree community was similar between the two time periods with hemlock dominant in both samples. Conversely, seedlings, saplings, and transgressives exhibited sharp declines in most species, including hemlock, which resulted in dissimilar community composition and structure for these age classes between 1965 and 2004. Despite relative continuity in the dominance of mature hemlocks, low recruitment due to overbrowsing makes the long-term persistence of hemlock in the old-growth forest of MRGP tenuous. #
Canadian Journal of Zoology, 2008
Declines in ruffed grouse (Bonasa umbellus (L., 1766)) populations in the central and southern Ap... more Declines in ruffed grouse (Bonasa umbellus (L., 1766)) populations in the central and southern Appalachians may be linked to low brood survival. Therefore, managing for high-quality brood habitat could improve grouse numbers. Understanding how brood habitat ...
Forest Ecology and …, 2010
Ruffed grouse (Bonasa umbellus; hereafter grouse) populations in the central and southern Appalac... more Ruffed grouse (Bonasa umbellus; hereafter grouse) populations in the central and southern Appalachians (CSA) are declining due to widespread maturation of forest cover. Effective management of this species requires a sex-and age-specific understanding of habitat preferences at multiple temporal and spatial scales. We used multivariate logistic regression models to compare habitat within 1440 grouse home ranges and 1400 equally sized buffered random points across 7 CSA study areas. On most sites, grouse home ranges were positively associated with roads and young forest (<20 years old). Sex and age status affected habitat preference. In general, males used younger forest than females, likely because of differences in habitat use during reproductive periods. Juveniles had fewer vegetation types preferred by adult grouse and more of the avoided vegetation types within their home ranges, indicative of competitive exclusion. Adult females had the greatest specificity and selectivity of habitat conditions within their home ranges. Habitat selection varied among seasons and years on most sites. Winter habitat use reflected behavior that maximized energy conservation, with open vegetation types avoided in the winter on the northernmost study areas, and topography important on all areas. Summer habitat selection reflected vegetation types associated with reproductive activities. Scale influenced habitat preference as well. Although roads and forest age predominantly influenced grouse home range location within the landscape, mesic forest types were most important in determining core area use within the home range. This was likely a result of increased food availability and favorable microclimate. Habitat management efforts should attempt to maintain ∼3-4% of the landscape in young forest cover (<20 years old), evenly distributed across management areas. Roads into these areas should be seeded as appropriate to enhance brood habitat and provide travel corridors connecting suitable forest stands.
Ecological Applications, Sep 1, 2011
Selection of a modeling approach is an important step in the conservation planning process, but l... more Selection of a modeling approach is an important step in the conservation planning process, but little guidance is available. We compared two statistical and three theoretical habitat modeling approaches representing those currently being used for avian conservation planning at landscape and regional scales: hierarchical spatial count (HSC), classification and regression tree (CRT), habitat suitability index (HSI), forest structure database (FS), and habitat association database (HA). We focused our comparison on models for five priority forest-breeding species in the Central Hardwoods Bird Conservation Region: Acadian Flycatcher, Cerulean Warbler, Prairie Warbler, Red-headed Woodpecker, and Worm-eating Warbler. Lacking complete knowledge on the distribution and abundance of each species with which we could illuminate differences between approaches and provide strong grounds for recommending one approach over another, we used two approaches to compare models: rank correlations among model outputs and comparison of spatial correspondence. In general, rank correlations were significantly positive among models for each species, indicating general agreement among the models. Worm-eating Warblers had the highest pairwise correlations, all of which were significant (P , 0.05). Red-headed Woodpeckers had the lowest agreement among models, suggesting greater uncertainty in the relative conservation value of areas within the region. We assessed model uncertainty by mapping the spatial congruence in priorities (i.e., top ranks) resulting from each model for each species and calculating the coefficient of variation across model ranks for each location. This allowed identification of areas more likely to be good targets of conservation effort for a species, those areas that were least likely, and those in between where uncertainty is higher and thus conservation action incorporates more risk. Based on our results, models developed independently for the same purpose (conservation planning for a particular species in a particular geography) yield different answers and thus different conservation strategies. We assert that using only one habitat model (even if validated) as the foundation of a conservation plan is risky. Using multiple models (i.e., ensemble prediction) can reduce uncertainty and increase efficacy of conservation action when models corroborate one another and increase understanding of the system when they do not.
Ecological Applications, Sep 1, 2011
Selection of a modeling approach is an important step in the conservation planning process, but l... more Selection of a modeling approach is an important step in the conservation planning process, but little guidance is available. We compared two statistical and three theoretical habitat modeling approaches representing those currently being used for avian conservation planning at landscape and regional scales: hierarchical spatial count (HSC), classification and regression tree (CRT), habitat suitability index (HSI), forest structure database (FS), and habitat association database (HA). We focused our comparison on models for five priority forest-breeding species in the Central Hardwoods Bird Conservation Region: Acadian Flycatcher, Cerulean Warbler, Prairie Warbler, Red-headed Woodpecker, and Worm-eating Warbler. Lacking complete knowledge on the distribution and abundance of each species with which we could illuminate differences between approaches and provide strong grounds for recommending one approach over another, we used two approaches to compare models: rank correlations among model outputs and comparison of spatial correspondence. In general, rank correlations were significantly positive among models for each species, indicating general agreement among the models. Worm-eating Warblers had the highest pairwise correlations, all of which were significant (P , 0.05). Red-headed Woodpeckers had the lowest agreement among models, suggesting greater uncertainty in the relative conservation value of areas within the region. We assessed model uncertainty by mapping the spatial congruence in priorities (i.e., top ranks) resulting from each model for each species and calculating the coefficient of variation across model ranks for each location. This allowed identification of areas more likely to be good targets of conservation effort for a species, those areas that were least likely, and those in between where uncertainty is higher and thus conservation action incorporates more risk. Based on our results, models developed independently for the same purpose (conservation planning for a particular species in a particular geography) yield different answers and thus different conservation strategies. We assert that using only one habitat model (even if validated) as the foundation of a conservation plan is risky. Using multiple models (i.e., ensemble prediction) can reduce uncertainty and increase efficacy of conservation action when models corroborate one another and increase understanding of the system when they do not.
Journal of Wildlife Management, 2007
... Mechanistic Home Range Analysis, by Paul R. Moorcroft and Mark A. Lewis. 2006. John M. Tirpak... more ... Mechanistic Home Range Analysis, by Paul R. Moorcroft and Mark A. Lewis. 2006. John M. Tirpak. ...Tirpak, JM (2007), Mechanistic Home Range Analysis, by Paul R. Moorcroft and Mark A. Lewis. 2006. The Journal of Wildlife Management, 71: 24442445. doi: 10.2193/2007-147. ...
Forest Ecology and Management - FOREST ECOL MANAGE, 2010
Like many similar forest species, ruffed grouse (Bonasa umbellus; hereafter grouse) populations i... more Like many similar forest species, ruffed grouse (Bonasa umbellus; hereafter grouse) populations in the central and southern Appalachians (CSA) are strongly affected by forest composition at the landscape scale. Because these populations are in decline, managers require accurate forest maps to understand how stand level characteristics affect the survival and reproductive potentials of individual birds to design management strategies that improve grouse abundance. However, traditional mapping techniques are often labor-intensive and cost-prohibitive. We used a normalized difference vegetation index (NDVI) from each of 8 Landsat images and the digital elevation model (DEM)-derived variables of elevation and aspect in discriminant analyses to classify 7 study areas to 3 overstory classes (evergreen, hardwoods, and oak) and distinguish evergreen and deciduous understories in the CSA, 2000-2002. Overall accuracy was 82.08%, varying from 83.59% for oak to 79.79% for hardwoods overstories. Periods with large phenological differences among classes, particularly early and late spring, were most useful for discriminating overstory vegetation types. Alternatively, winter NDVI in combination with elevation was critical for differentiating evergreen and deciduous understories. Multitemporal image sets used in concert with DEMs provided a cost-effective alternative to hyperspectral sensors for improving wildlife habitat classification accuracy with Landsat imagery. This allowed for enhanced understanding of grouse-habitat relationships and habitat affects on grouse populations that allowed for improved management. With the incorporation of simple adjustments for local forest plant species phenology into the model, it may be used to better classify wildlife habitat of similar species in areas with comparable forest communities and topography. Multitemporal images can also be used to differentiate grassland communities, monitor wetlands, and serve as baseline data for detecting changes in land use over longer temporal scales, making their use in forest wildlife habitat studies cost-justifiable.
Forest Ecology and Management, 2006
Eastern hemlock (Tsuga canadensis; hereafter hemlock) was once relatively common in the northeast... more Eastern hemlock (Tsuga canadensis; hereafter hemlock) was once relatively common in the northeastern United States. However, recent disturbances -including exotic pests and white-tailed deer overpopulation -have exacerbated declines in hemlock forest in the 20th century. As a previously undisturbed stand, the Mianus River Gorge Preserve (MRGP) provided an ideal site to investigate the potential impact of these factors on the structure and composition of old-growth hemlock forests. The woody vegetation of this forest was first surveyed in 1965 and then again in 2004. The overstory tree community was similar between the two time periods with hemlock dominant in both samples. Conversely, seedlings, saplings, and transgressives exhibited sharp declines in most species, including hemlock, which resulted in dissimilar community composition and structure for these age classes between 1965 and 2004. Despite relative continuity in the dominance of mature hemlocks, low recruitment due to overbrowsing makes the long-term persistence of hemlock in the old-growth forest of MRGP tenuous. #
Journal of Wildlife Management, 2007
... Mechanistic Home Range Analysis, by Paul R. Moorcroft and Mark A. Lewis. 2006. John M. Tirpak... more ... Mechanistic Home Range Analysis, by Paul R. Moorcroft and Mark A. Lewis. 2006. John M. Tirpak. ...Tirpak, JM (2007), Mechanistic Home Range Analysis, by Paul R. Moorcroft and Mark A. Lewis. 2006. The Journal of Wildlife Management, 71: 24442445. doi: 10.2193/2007-147. ...
Canadian Journal of Zoology, 2008
Declines in ruffed grouse (Bonasa umbellus (L., 1766)) populations in the central and southern Ap... more Declines in ruffed grouse (Bonasa umbellus (L., 1766)) populations in the central and southern Appalachians may be linked to low brood survival. Therefore, managing for high-quality brood habitat could improve grouse numbers. Understanding how brood habitat ...
Forest Ecology and Management - FOREST ECOL MANAGE, 2010
Like many similar forest species, ruffed grouse (Bonasa umbellus; hereafter grouse) populations i... more Like many similar forest species, ruffed grouse (Bonasa umbellus; hereafter grouse) populations in the central and southern Appalachians (CSA) are strongly affected by forest composition at the landscape scale. Because these populations are in decline, managers require accurate forest maps to understand how stand level characteristics affect the survival and reproductive potentials of individual birds to design management strategies that improve grouse abundance. However, traditional mapping techniques are often labor-intensive and cost-prohibitive. We used a normalized difference vegetation index (NDVI) from each of 8 Landsat images and the digital elevation model (DEM)-derived variables of elevation and aspect in discriminant analyses to classify 7 study areas to 3 overstory classes (evergreen, hardwoods, and oak) and distinguish evergreen and deciduous understories in the CSA, 2000-2002. Overall accuracy was 82.08%, varying from 83.59% for oak to 79.79% for hardwoods overstories. Periods with large phenological differences among classes, particularly early and late spring, were most useful for discriminating overstory vegetation types. Alternatively, winter NDVI in combination with elevation was critical for differentiating evergreen and deciduous understories. Multitemporal image sets used in concert with DEMs provided a cost-effective alternative to hyperspectral sensors for improving wildlife habitat classification accuracy with Landsat imagery. This allowed for enhanced understanding of grouse-habitat relationships and habitat affects on grouse populations that allowed for improved management. With the incorporation of simple adjustments for local forest plant species phenology into the model, it may be used to better classify wildlife habitat of similar species in areas with comparable forest communities and topography. Multitemporal images can also be used to differentiate grassland communities, monitor wetlands, and serve as baseline data for detecting changes in land use over longer temporal scales, making their use in forest wildlife habitat studies cost-justifiable.
Forest Ecology and …, 2010
Ruffed grouse (Bonasa umbellus; hereafter grouse) populations in the central and southern Appalac... more Ruffed grouse (Bonasa umbellus; hereafter grouse) populations in the central and southern Appalachians (CSA) are declining due to widespread maturation of forest cover. Effective management of this species requires a sex-and age-specific understanding of habitat preferences at multiple temporal and spatial scales. We used multivariate logistic regression models to compare habitat within 1440 grouse home ranges and 1400 equally sized buffered random points across 7 CSA study areas. On most sites, grouse home ranges were positively associated with roads and young forest (<20 years old). Sex and age status affected habitat preference. In general, males used younger forest than females, likely because of differences in habitat use during reproductive periods. Juveniles had fewer vegetation types preferred by adult grouse and more of the avoided vegetation types within their home ranges, indicative of competitive exclusion. Adult females had the greatest specificity and selectivity of habitat conditions within their home ranges. Habitat selection varied among seasons and years on most sites. Winter habitat use reflected behavior that maximized energy conservation, with open vegetation types avoided in the winter on the northernmost study areas, and topography important on all areas. Summer habitat selection reflected vegetation types associated with reproductive activities. Scale influenced habitat preference as well. Although roads and forest age predominantly influenced grouse home range location within the landscape, mesic forest types were most important in determining core area use within the home range. This was likely a result of increased food availability and favorable microclimate. Habitat management efforts should attempt to maintain ∼3-4% of the landscape in young forest cover (<20 years old), evenly distributed across management areas. Roads into these areas should be seeded as appropriate to enhance brood habitat and provide travel corridors connecting suitable forest stands.
Forest Ecology and Management, 2006
Eastern hemlock (Tsuga canadensis; hereafter hemlock) was once relatively common in the northeast... more Eastern hemlock (Tsuga canadensis; hereafter hemlock) was once relatively common in the northeastern United States. However, recent disturbances -including exotic pests and white-tailed deer overpopulation -have exacerbated declines in hemlock forest in the 20th century. As a previously undisturbed stand, the Mianus River Gorge Preserve (MRGP) provided an ideal site to investigate the potential impact of these factors on the structure and composition of old-growth hemlock forests. The woody vegetation of this forest was first surveyed in 1965 and then again in 2004. The overstory tree community was similar between the two time periods with hemlock dominant in both samples. Conversely, seedlings, saplings, and transgressives exhibited sharp declines in most species, including hemlock, which resulted in dissimilar community composition and structure for these age classes between 1965 and 2004. Despite relative continuity in the dominance of mature hemlocks, low recruitment due to overbrowsing makes the long-term persistence of hemlock in the old-growth forest of MRGP tenuous. #
Canadian Journal of Zoology, 2008
Declines in ruffed grouse (Bonasa umbellus (L., 1766)) populations in the central and southern Ap... more Declines in ruffed grouse (Bonasa umbellus (L., 1766)) populations in the central and southern Appalachians may be linked to low brood survival. Therefore, managing for high-quality brood habitat could improve grouse numbers. Understanding how brood habitat ...
Forest Ecology and …, 2010
Ruffed grouse (Bonasa umbellus; hereafter grouse) populations in the central and southern Appalac... more Ruffed grouse (Bonasa umbellus; hereafter grouse) populations in the central and southern Appalachians (CSA) are declining due to widespread maturation of forest cover. Effective management of this species requires a sex-and age-specific understanding of habitat preferences at multiple temporal and spatial scales. We used multivariate logistic regression models to compare habitat within 1440 grouse home ranges and 1400 equally sized buffered random points across 7 CSA study areas. On most sites, grouse home ranges were positively associated with roads and young forest (<20 years old). Sex and age status affected habitat preference. In general, males used younger forest than females, likely because of differences in habitat use during reproductive periods. Juveniles had fewer vegetation types preferred by adult grouse and more of the avoided vegetation types within their home ranges, indicative of competitive exclusion. Adult females had the greatest specificity and selectivity of habitat conditions within their home ranges. Habitat selection varied among seasons and years on most sites. Winter habitat use reflected behavior that maximized energy conservation, with open vegetation types avoided in the winter on the northernmost study areas, and topography important on all areas. Summer habitat selection reflected vegetation types associated with reproductive activities. Scale influenced habitat preference as well. Although roads and forest age predominantly influenced grouse home range location within the landscape, mesic forest types were most important in determining core area use within the home range. This was likely a result of increased food availability and favorable microclimate. Habitat management efforts should attempt to maintain ∼3-4% of the landscape in young forest cover (<20 years old), evenly distributed across management areas. Roads into these areas should be seeded as appropriate to enhance brood habitat and provide travel corridors connecting suitable forest stands.
Ecological Applications, Sep 1, 2011
Selection of a modeling approach is an important step in the conservation planning process, but l... more Selection of a modeling approach is an important step in the conservation planning process, but little guidance is available. We compared two statistical and three theoretical habitat modeling approaches representing those currently being used for avian conservation planning at landscape and regional scales: hierarchical spatial count (HSC), classification and regression tree (CRT), habitat suitability index (HSI), forest structure database (FS), and habitat association database (HA). We focused our comparison on models for five priority forest-breeding species in the Central Hardwoods Bird Conservation Region: Acadian Flycatcher, Cerulean Warbler, Prairie Warbler, Red-headed Woodpecker, and Worm-eating Warbler. Lacking complete knowledge on the distribution and abundance of each species with which we could illuminate differences between approaches and provide strong grounds for recommending one approach over another, we used two approaches to compare models: rank correlations among model outputs and comparison of spatial correspondence. In general, rank correlations were significantly positive among models for each species, indicating general agreement among the models. Worm-eating Warblers had the highest pairwise correlations, all of which were significant (P , 0.05). Red-headed Woodpeckers had the lowest agreement among models, suggesting greater uncertainty in the relative conservation value of areas within the region. We assessed model uncertainty by mapping the spatial congruence in priorities (i.e., top ranks) resulting from each model for each species and calculating the coefficient of variation across model ranks for each location. This allowed identification of areas more likely to be good targets of conservation effort for a species, those areas that were least likely, and those in between where uncertainty is higher and thus conservation action incorporates more risk. Based on our results, models developed independently for the same purpose (conservation planning for a particular species in a particular geography) yield different answers and thus different conservation strategies. We assert that using only one habitat model (even if validated) as the foundation of a conservation plan is risky. Using multiple models (i.e., ensemble prediction) can reduce uncertainty and increase efficacy of conservation action when models corroborate one another and increase understanding of the system when they do not.
Ecological Applications, Sep 1, 2011
Selection of a modeling approach is an important step in the conservation planning process, but l... more Selection of a modeling approach is an important step in the conservation planning process, but little guidance is available. We compared two statistical and three theoretical habitat modeling approaches representing those currently being used for avian conservation planning at landscape and regional scales: hierarchical spatial count (HSC), classification and regression tree (CRT), habitat suitability index (HSI), forest structure database (FS), and habitat association database (HA). We focused our comparison on models for five priority forest-breeding species in the Central Hardwoods Bird Conservation Region: Acadian Flycatcher, Cerulean Warbler, Prairie Warbler, Red-headed Woodpecker, and Worm-eating Warbler. Lacking complete knowledge on the distribution and abundance of each species with which we could illuminate differences between approaches and provide strong grounds for recommending one approach over another, we used two approaches to compare models: rank correlations among model outputs and comparison of spatial correspondence. In general, rank correlations were significantly positive among models for each species, indicating general agreement among the models. Worm-eating Warblers had the highest pairwise correlations, all of which were significant (P , 0.05). Red-headed Woodpeckers had the lowest agreement among models, suggesting greater uncertainty in the relative conservation value of areas within the region. We assessed model uncertainty by mapping the spatial congruence in priorities (i.e., top ranks) resulting from each model for each species and calculating the coefficient of variation across model ranks for each location. This allowed identification of areas more likely to be good targets of conservation effort for a species, those areas that were least likely, and those in between where uncertainty is higher and thus conservation action incorporates more risk. Based on our results, models developed independently for the same purpose (conservation planning for a particular species in a particular geography) yield different answers and thus different conservation strategies. We assert that using only one habitat model (even if validated) as the foundation of a conservation plan is risky. Using multiple models (i.e., ensemble prediction) can reduce uncertainty and increase efficacy of conservation action when models corroborate one another and increase understanding of the system when they do not.