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Papers by Clay Trauernicht
Human-Imposed, Fine-Grained Patch Burning Explains the Population Stability of a Fire-Sensitive Conifer in a Frequently Burnt Northern Australia Savanna
Ecosystems, 2016
The Contemporary Scale and Context of Wildfire in Hawai‘i 1
Pacific Science, 2015
Future directions for forest restoration in Hawai‘i
New Forests, 2015
Ecology and Evolution, 2015
Ecology and evolution, 2013
We use the fire ecology and biogeographical patterns of Callitris intratropica, a fire-sensitive ... more We use the fire ecology and biogeographical patterns of Callitris intratropica, a fire-sensitive conifer, and the Asian water buffalo (Bubalus bubalis), an introduced mega-herbivore, to examine the hypothesis that the continuation of Aboriginal burning and cultural integration of buffalo contribute to greater savanna heterogeneity and diversity in central Arnhem Land (CAL) than Kakadu National Park (KNP). The 'Stone Country' of the Arnhem Plateau, extending from KNP to CAL, is a globally renowned social-ecological system, managed for millennia by Bininj-Kunwok Aboriginal clans. Regional species declines have been attributed to the cessation of patchy burning by Aborigines. Whereas the KNP Stone Country is a modern wilderness, managed through prescribed burning and buffalo eradication, CAL remains a stronghold for Aboriginal management where buffalo have been culturally integrated. We surveyed the plant community and the presence of buffalo tracks among intact and fire-damage...
Journal of Ecology, 2012
1. Callitris intratropica is a long-lived, obligate-seeding, fire-sensitive overstorey conifer th... more 1. Callitris intratropica is a long-lived, obligate-seeding, fire-sensitive overstorey conifer that typically occurs in small groves (<0.1 ha) of much higher tree densities than the surrounding, eucalypt-dominated tropical savanna in northern Australia. We used C. intratropica groves of varying canopy cover to examine the role of feedbacks between fire and tree cover in the persistence of a fire-sensitive tree species and the maintenance of habitat heterogeneity in a highly flammable savanna. 2. We examined the population structure and floristic composition of C. intratropica groves and conducted controlled burns with Aboriginal landowners to test the prediction that groves of C. intratropica with closed canopies inhibit savanna fires by physically altering the fuel arrays below trees. We measured pre-and post-burn fuel availability, the probability of burning and fire intensity along transects (55-75 m) spanning entire C. intratropica groves and extending into the surrounding savanna matrix. 3. We found that closed-canopy groves of C. intratropica had higher densities of seedlings and saplings than open-canopy groves and supported a distinct plant community. Closed-canopy groves also had a lower probability of burning and less severe fires due to a lower availability of fine fuels than the surrounding savanna. 4. Synthesis. Our results suggest that the observed regeneration within closed-canopy C. intratropica groves within frequently burnt savanna reflects a vegetation-fire feedback. A significant, negative relationship between canopy cover and the probability of burning provides strong evidence that closed-canopy C. intratropica groves are capable of excluding low-intensity savanna fires, thereby enabling the persistence of patches of fire-sensitive forest or woodland amid open, highly flammable savanna vegetation. We present our findings as evidence that alternative stable state dynamics may play a role in determining savanna diversity and structure.
Forest Ecology and Management, 2005
The planting of non-timber forest products (NTFPs) in the understory of tropical forests is promo... more The planting of non-timber forest products (NTFPs) in the understory of tropical forests is promoted in many parts of the world as a strategy to conserve forested lands and meet the economic needs of rural communities. While many studies of NTFP management have focused on the effects of harvesting on wild populations, the impacts of understory NTFP plantations, or enrichment plantings, on forest community composition and structure have not been investigated. We assessed the effects of understory plantations of the palm Chamaedorea hooperiana Hodel, on community composition and structure of an old growth tropical rain forest in the Los Tuxtlas Biosphere Reserve in southeastern Mexico. A blocked design consisting of four C. hooperiana plantation sites each paired with an adjacent site of unmanaged forest was used to compare the plant species richness and diversity, stem density, basal area and size class structure in plantations versus unmanaged forest. In each site, 12 10 m diameter plots were established for a total of 96 plots (4 blocks  2 sites  12 plots). Although the stem density, diversity, richness and basal area of large overstory trees (!20 cm dbh) were unaffected by the establishment and management of understory palm plantations, the stem density, species richness and basal area of woody species in smaller size classes (<10 cm dbh) were significantly lower in plantation sites than in similar unmanaged forest sites. The density of naturally occurring, economically valuable palm species was unaffected by the C. hooperiana plantations, indicating that these understory species are spared when plantations are established and maintained. However, plantation sites showed significant reductions in the density of the midstory palm Astrocaryum mexicanum, the most abundant plant in unmanaged forest sites. The removal of vegetation in NTFP plantations may result in the fragmentation and/or elimination of local populations of understory and midstory plant species. In addition, changes to the composition of advanced regeneration due to the removal of canopy tree seedlings and saplings may have implications for future patterns of forest regeneration and composition. Nonetheless, NTFP cultivation offers a promising alternative to more destructive forms of land uses in the tropics and warrants further attention as a forest management strategy.
Biotropica, 2006
The planting of non-timber forest products (NTFPs) in the understory of tropical forests is promo... more The planting of non-timber forest products (NTFPs) in the understory of tropical forests is promoted in many regions as a strategy to conserve forested lands and meet the economic needs of rural communities. While the forest canopy is left intact in most understory plantations, much of the midstory and understory vegetation is removed in order to increase light availability for cultivated species. We assessed the extent to which the removal of vegetation in understory plantations of Chamaedorea hooperiana Hodel (Arecaceae) alters understory light conditions. We also examined how any changes in light availability may be reflected by changes in the composition of canopy tree seedlings regenerating in understory plantations. We employed a blocked design consisting of four C. hooperiana plantation sites; each site was paired with an adjacent, unmanaged forest site. Hemispherical canopy photographs were taken and canopy tree seedlings were identified and measured within 12 3 × 2 m randomly placed plots in each site for a total of 96 plots (4 blocks × 2 sites × 12 plots). Plantation management did not affect canopy openness or direct light availability but understory plantations had a higher frequency of plots with greater total and diffuse light availability than unmanaged forest. Comparisons of canopy tree seedling composition between understory plantations and unmanaged forest sites were less conclusive but suggest that management practices have the potential to increase the proportion of shade-intolerant species of tree seedlings establishing in plantations. Given the importance of advanced regeneration in gap-phase forest dynamics, these changes may have implications for future patterns of succession in the areas of forest where NTFPs are cultivated.
The Fire Refuge Value of Patches of a Fire-Sensitive Tree in Fire-prone Savannas: Callitris intratropica in Northern Australia
Biotropica, 2013
ABSTRACT Patches of fire-sensitive vegetation often occur within fire-prone tropical savannas, an... more ABSTRACT Patches of fire-sensitive vegetation often occur within fire-prone tropical savannas, and are indicative of localized areas where fire regimes are less severe. These may act as important fire refugia for fire-sensitive biota. The fire-sensitive tree Callitris intratropica occurs in small patches throughout the fire-prone northern Australian savannas, and is widely seen as an indicator of low-severity fire regimes and of good ecosystem health. Here, we address the question: to what extent do Callitris patches act as refuges for other fire-sensitive biota, and therefore play a broader conservation role? We contrast floral and faunal species composition between Callitris patches and surrounding eucalypt savanna, using three case studies. In the first case study, a floristic analysis of 47 Callitris patches across Western Australia's Kimberley region showed that woody species in these patches were overwhelmingly widespread, fire-tolerant savanna taxa. No species of special conservation concern occurred disproportionately within Callitris patches. Similarly, there was no concentration of fire-sensitive fauna or flora in five Callitris patches in the East Kimberley. Finally, there was no difference in ant species composition among 12 Callitris patches and surrounding eucalypt savannas in Kakadu National Park, Northern Territory, and there were no fire-sensitive ant species in Callitris patches. Our three case studies from throughout the northwestern Australia provide no evidence that Callitris patches act as important refuges for fire-sensitive flora or fauna within fire-prone eucalypt savannas. This calls into question the notion that Callitris is a strong indicator of general ecosystem health.
Human-Imposed, Fine-Grained Patch Burning Explains the Population Stability of a Fire-Sensitive Conifer in a Frequently Burnt Northern Australia Savanna
Ecosystems, 2016
The Contemporary Scale and Context of Wildfire in Hawai‘i 1
Pacific Science, 2015
Future directions for forest restoration in Hawai‘i
New Forests, 2015
Ecology and Evolution, 2015
Ecology and evolution, 2013
We use the fire ecology and biogeographical patterns of Callitris intratropica, a fire-sensitive ... more We use the fire ecology and biogeographical patterns of Callitris intratropica, a fire-sensitive conifer, and the Asian water buffalo (Bubalus bubalis), an introduced mega-herbivore, to examine the hypothesis that the continuation of Aboriginal burning and cultural integration of buffalo contribute to greater savanna heterogeneity and diversity in central Arnhem Land (CAL) than Kakadu National Park (KNP). The 'Stone Country' of the Arnhem Plateau, extending from KNP to CAL, is a globally renowned social-ecological system, managed for millennia by Bininj-Kunwok Aboriginal clans. Regional species declines have been attributed to the cessation of patchy burning by Aborigines. Whereas the KNP Stone Country is a modern wilderness, managed through prescribed burning and buffalo eradication, CAL remains a stronghold for Aboriginal management where buffalo have been culturally integrated. We surveyed the plant community and the presence of buffalo tracks among intact and fire-damage...
Journal of Ecology, 2012
1. Callitris intratropica is a long-lived, obligate-seeding, fire-sensitive overstorey conifer th... more 1. Callitris intratropica is a long-lived, obligate-seeding, fire-sensitive overstorey conifer that typically occurs in small groves (<0.1 ha) of much higher tree densities than the surrounding, eucalypt-dominated tropical savanna in northern Australia. We used C. intratropica groves of varying canopy cover to examine the role of feedbacks between fire and tree cover in the persistence of a fire-sensitive tree species and the maintenance of habitat heterogeneity in a highly flammable savanna. 2. We examined the population structure and floristic composition of C. intratropica groves and conducted controlled burns with Aboriginal landowners to test the prediction that groves of C. intratropica with closed canopies inhibit savanna fires by physically altering the fuel arrays below trees. We measured pre-and post-burn fuel availability, the probability of burning and fire intensity along transects (55-75 m) spanning entire C. intratropica groves and extending into the surrounding savanna matrix. 3. We found that closed-canopy groves of C. intratropica had higher densities of seedlings and saplings than open-canopy groves and supported a distinct plant community. Closed-canopy groves also had a lower probability of burning and less severe fires due to a lower availability of fine fuels than the surrounding savanna. 4. Synthesis. Our results suggest that the observed regeneration within closed-canopy C. intratropica groves within frequently burnt savanna reflects a vegetation-fire feedback. A significant, negative relationship between canopy cover and the probability of burning provides strong evidence that closed-canopy C. intratropica groves are capable of excluding low-intensity savanna fires, thereby enabling the persistence of patches of fire-sensitive forest or woodland amid open, highly flammable savanna vegetation. We present our findings as evidence that alternative stable state dynamics may play a role in determining savanna diversity and structure.
Forest Ecology and Management, 2005
The planting of non-timber forest products (NTFPs) in the understory of tropical forests is promo... more The planting of non-timber forest products (NTFPs) in the understory of tropical forests is promoted in many parts of the world as a strategy to conserve forested lands and meet the economic needs of rural communities. While many studies of NTFP management have focused on the effects of harvesting on wild populations, the impacts of understory NTFP plantations, or enrichment plantings, on forest community composition and structure have not been investigated. We assessed the effects of understory plantations of the palm Chamaedorea hooperiana Hodel, on community composition and structure of an old growth tropical rain forest in the Los Tuxtlas Biosphere Reserve in southeastern Mexico. A blocked design consisting of four C. hooperiana plantation sites each paired with an adjacent site of unmanaged forest was used to compare the plant species richness and diversity, stem density, basal area and size class structure in plantations versus unmanaged forest. In each site, 12 10 m diameter plots were established for a total of 96 plots (4 blocks  2 sites  12 plots). Although the stem density, diversity, richness and basal area of large overstory trees (!20 cm dbh) were unaffected by the establishment and management of understory palm plantations, the stem density, species richness and basal area of woody species in smaller size classes (<10 cm dbh) were significantly lower in plantation sites than in similar unmanaged forest sites. The density of naturally occurring, economically valuable palm species was unaffected by the C. hooperiana plantations, indicating that these understory species are spared when plantations are established and maintained. However, plantation sites showed significant reductions in the density of the midstory palm Astrocaryum mexicanum, the most abundant plant in unmanaged forest sites. The removal of vegetation in NTFP plantations may result in the fragmentation and/or elimination of local populations of understory and midstory plant species. In addition, changes to the composition of advanced regeneration due to the removal of canopy tree seedlings and saplings may have implications for future patterns of forest regeneration and composition. Nonetheless, NTFP cultivation offers a promising alternative to more destructive forms of land uses in the tropics and warrants further attention as a forest management strategy.
Biotropica, 2006
The planting of non-timber forest products (NTFPs) in the understory of tropical forests is promo... more The planting of non-timber forest products (NTFPs) in the understory of tropical forests is promoted in many regions as a strategy to conserve forested lands and meet the economic needs of rural communities. While the forest canopy is left intact in most understory plantations, much of the midstory and understory vegetation is removed in order to increase light availability for cultivated species. We assessed the extent to which the removal of vegetation in understory plantations of Chamaedorea hooperiana Hodel (Arecaceae) alters understory light conditions. We also examined how any changes in light availability may be reflected by changes in the composition of canopy tree seedlings regenerating in understory plantations. We employed a blocked design consisting of four C. hooperiana plantation sites; each site was paired with an adjacent, unmanaged forest site. Hemispherical canopy photographs were taken and canopy tree seedlings were identified and measured within 12 3 × 2 m randomly placed plots in each site for a total of 96 plots (4 blocks × 2 sites × 12 plots). Plantation management did not affect canopy openness or direct light availability but understory plantations had a higher frequency of plots with greater total and diffuse light availability than unmanaged forest. Comparisons of canopy tree seedling composition between understory plantations and unmanaged forest sites were less conclusive but suggest that management practices have the potential to increase the proportion of shade-intolerant species of tree seedlings establishing in plantations. Given the importance of advanced regeneration in gap-phase forest dynamics, these changes may have implications for future patterns of succession in the areas of forest where NTFPs are cultivated.
The Fire Refuge Value of Patches of a Fire-Sensitive Tree in Fire-prone Savannas: Callitris intratropica in Northern Australia
Biotropica, 2013
ABSTRACT Patches of fire-sensitive vegetation often occur within fire-prone tropical savannas, an... more ABSTRACT Patches of fire-sensitive vegetation often occur within fire-prone tropical savannas, and are indicative of localized areas where fire regimes are less severe. These may act as important fire refugia for fire-sensitive biota. The fire-sensitive tree Callitris intratropica occurs in small patches throughout the fire-prone northern Australian savannas, and is widely seen as an indicator of low-severity fire regimes and of good ecosystem health. Here, we address the question: to what extent do Callitris patches act as refuges for other fire-sensitive biota, and therefore play a broader conservation role? We contrast floral and faunal species composition between Callitris patches and surrounding eucalypt savanna, using three case studies. In the first case study, a floristic analysis of 47 Callitris patches across Western Australia's Kimberley region showed that woody species in these patches were overwhelmingly widespread, fire-tolerant savanna taxa. No species of special conservation concern occurred disproportionately within Callitris patches. Similarly, there was no concentration of fire-sensitive fauna or flora in five Callitris patches in the East Kimberley. Finally, there was no difference in ant species composition among 12 Callitris patches and surrounding eucalypt savannas in Kakadu National Park, Northern Territory, and there were no fire-sensitive ant species in Callitris patches. Our three case studies from throughout the northwestern Australia provide no evidence that Callitris patches act as important refuges for fire-sensitive flora or fauna within fire-prone eucalypt savannas. This calls into question the notion that Callitris is a strong indicator of general ecosystem health.