Canadian Journal of Forest Research-revue Canadienne De Recherche Forestiere, 2007
Thinning and prescribed fire are widely used to restore fire-suppressed forests, yet there are fe... more Thinning and prescribed fire are widely used to restore fire-suppressed forests, yet there are few studies of their effectiveness in Sierran mixed-conifer forest. We compared stand conditions in replicated plots before and after a combination of thinning and burning treatments against a reconstruction of the same forest in 1865. The historical forest had 67 stems/ha (trees 5 cm DBH), equal percentages of shade-tolerant and -intolerant tree species, stems randomly distributed at the stand scale, and a flat diameter distribution across size classes. The pretreatment forest averaged 469 stems/ha, which comprised 84% shade-tolerant and 14% shade-intolerant species, were highly clustered, and had a reverse-J-shaped diameter distribution. Thinning treatments failed to approximate historical composition, spatial pattern, or diameter distribution. Treatments left too many small trees, removed too many intermediate-sized trees (50-75 cm DBH), and retained a reverse-J-shaped diameter distribution. Current old growth comprises fewer large trees than historical conditions, suggesting that treatments should retain more intermediate-sized trees to provide for future large-tree recruitment. Understory thinning with prescribed fire significantly reduced stem density and produced a spatial pattern closest to historical conditions. Mixed-conifer restoration needs thinning prescriptions that vary by species and flexible rather than rigid upper diameter limits to retain some trees in all size classes.
Methods for habitat modeling based on landscape simulations and population viability modeling bas... more Methods for habitat modeling based on landscape simulations and population viability modeling based on habitat quality are well developed, but no published study of which we are aware has effectively joined them in a single, comprehensive analysis. We demonstrate the application of a population viability model for ovenbirds (Seiurus aumcapillus) that is linked to realistic landscape simulations using a GIs-based habitat suitability index (HSI) model. We simulated potential future characteristics of a hardwood forest in southern Missouri under two tree harvest scenarios using LANDIS. We applied three different versions of the HSI model (lower, best, and upper estimates) to output from the landscape simulations and used RAMAS GIs to link estimates of temporally dynamic habitat suitability, through fecundity and carrying capacity, to ovenbird population viability. Abundances and viability differed more between the upper and lower HSI estimates than between the two forest management scenarios. The viability model was as sensitive to the relationship between reproductive success and habitat suitability as it was to rates of first-year survival and reproductive success itself. Habitat-based viability models and the wildlife studies they support, therefore, would benefit greatly from improving the accuracy and precision of habitat suitability estimates.
Canadian Journal of Forest Research-revue Canadienne De Recherche Forestiere, 2007
Thinning and prescribed fire are widely used to restore fire-suppressed forests, yet there are fe... more Thinning and prescribed fire are widely used to restore fire-suppressed forests, yet there are few studies of their effectiveness in Sierran mixed-conifer forest. We compared stand conditions in replicated plots before and after a combination of thinning and burning treatments against a reconstruction of the same forest in 1865. The historical forest had 67 stems/ha (trees 5 cm DBH), equal percentages of shade-tolerant and -intolerant tree species, stems randomly distributed at the stand scale, and a flat diameter distribution across size classes. The pretreatment forest averaged 469 stems/ha, which comprised 84% shade-tolerant and 14% shade-intolerant species, were highly clustered, and had a reverse-J-shaped diameter distribution. Thinning treatments failed to approximate historical composition, spatial pattern, or diameter distribution. Treatments left too many small trees, removed too many intermediate-sized trees (50-75 cm DBH), and retained a reverse-J-shaped diameter distribution. Current old growth comprises fewer large trees than historical conditions, suggesting that treatments should retain more intermediate-sized trees to provide for future large-tree recruitment. Understory thinning with prescribed fire significantly reduced stem density and produced a spatial pattern closest to historical conditions. Mixed-conifer restoration needs thinning prescriptions that vary by species and flexible rather than rigid upper diameter limits to retain some trees in all size classes.
Methods for habitat modeling based on landscape simulations and population viability modeling bas... more Methods for habitat modeling based on landscape simulations and population viability modeling based on habitat quality are well developed, but no published study of which we are aware has effectively joined them in a single, comprehensive analysis. We demonstrate the application of a population viability model for ovenbirds (Seiurus aumcapillus) that is linked to realistic landscape simulations using a GIs-based habitat suitability index (HSI) model. We simulated potential future characteristics of a hardwood forest in southern Missouri under two tree harvest scenarios using LANDIS. We applied three different versions of the HSI model (lower, best, and upper estimates) to output from the landscape simulations and used RAMAS GIs to link estimates of temporally dynamic habitat suitability, through fecundity and carrying capacity, to ovenbird population viability. Abundances and viability differed more between the upper and lower HSI estimates than between the two forest management scenarios. The viability model was as sensitive to the relationship between reproductive success and habitat suitability as it was to rates of first-year survival and reproductive success itself. Habitat-based viability models and the wildlife studies they support, therefore, would benefit greatly from improving the accuracy and precision of habitat suitability estimates.
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Papers by Raphael Landi