The Experts below are selected from a list of 7458 Experts worldwide ranked by ideXlab platform
Paula Marchelli - One of the best experts on this subject based on the ideXlab platform.
-
Clinal variation along precipitation gradients in Patagonian temperate forests: unravelling demographic and selection signatures in three Nothofagus spp.
Annals of Forest Science, 2020Co-Authors: Carolina Soliani, Maria Marta Azpilicueta, María Verónica Arana, Paula MarchelliAbstract:Key message Past demographic changes and current selection pressures determine the genetic variation displayed by Nothofagus species along rainfall gradients. Based on the diversity trends observed at candidate genes associated to drought stress, we inferred a differential species’ adaptive potential. Context Clinal genetic variation in natural populations could reflect either recent demographic history or the evolution of adapted genotypes along heterogeneous environments. Aims We describe genetic variation patterns in three Nothofagus species of South American temperate forests, growing along steep rainfall gradients. Our hypothesis is that the selection pressure along this gradient reinforces the genetic structure previously shaped by Pleistocene climate oscillations. Methods We screened variation along gradients at putative adaptive markers: candidate genes involved in response to drought, and EST-SSRs linked to drought stress genes. Genomic SSRs (gSSRs) were used to decouple the incidence of demographic events in the genetic structure. Results Genetic diversity at SSRs agreed with the putative location of cryptic Pleistocene refugia in Nothofagus . In addition, each species showed different trends for nucleotide diversity at candidate genes. Unbiased heterozygosity significantly correlated with precipitation at EST-SSRs in Nothofagus nervosa . We found evidences of balancing selection and several SNPs departed from neutral expectations. Conclusions Nothofagus genetic variability shows a strong imprint of demographic changes that reveals refugia location for the species during Pleistocene. This variability is modelled by environmental conditions across natural gradients, which impose selection pressure at genome regions related to stress response, providing clues about inter-specific differences in adaptive potential to water deficit.
-
distribucion natural de Nothofagus alpina y Nothofagus obliqua nothofagaceae en argentina dos especies de primera importancia forestal de los bosques templados norpatagonicos
Boletin de la Sociedad Argentina de Botanica, 2011Co-Authors: Yamila Sabatier, Maria Marta Azpilicueta, Paula Marchelli, Marcelo Gonzalezpenalba, Liliana Lozano, Leandro Garcia, Abel Martinez, Leonardo A Gallo, Fernando UmanaAbstract:Summary: Natural distribution of Nothofagus alpina and Nothofagus obliqua (Nothofagaceae) in Argentina, two productively important tree species of the North Patagonian temperate forests. Knowing the natural range of any species is essential to plan its conservation or use. The South-American beeches Rauli [Nothofagus alpina (Poepp. & Endl.) Oerst. = Nothofagus nervosa (Phil.) Dim. et Mil.] and Roble Pellin [Nothofagus obliqua (Mirb.) Oerst. ssp. obliqua] are two important forest tree species of the North Patagonian forests, and the object of a current domestication program. Natural distribution of both beeches in Argentina was mapped based on digital information of previous works which was verified by local qualified informants, ground control check and visual interpretation of images freely provided by Google Earth. Rauli is present over a surface of 79,636 ha, while 33,859 ha are occupied by forests with the presence of Roble Pellin. 97 % of the Rauli and 83 % of the Roble Pellin surfaces are under the protection of the National Park Administration. However, many forests of particular conservation relevance are under the Neuquen Province jurisdiction, what should be considered when planning a conservation strategy for both species.
Thomas T Veblen - One of the best experts on this subject based on the ideXlab platform.
-
Spatial prediction of caterpillar (Ormiscodes) defoliation in Patagonian Nothofagus forests
Landscape Ecology, 2011Co-Authors: Juan Paritsis, Thomas T Veblen, Jeremy M. Smith, Andrés HolzAbstract:In the temperate forests of the southern Andes, southern beech species ( Nothofagus ), the dominant tree species of the region, experience severe defoliation caused by caterpillars of the Ormiscodes genus (Lepidoptera: Saturniidae). Despite the recent increase in defoliation frequency in some areas, there is no quantitative information on the spatial extent and dynamics of these outbreaks. This study examines the spatial patterns of O. amphimone outbreaks in relation to landscape heterogeneity. We mapped defoliation events caused by O. amphimone in northern (ca. 40–41°S) and southern Patagonian (ca. 49°S) Nothofagus forests from Landsat imagery and analyzed their spatial associations with vegetation cover type, topography (elevation, slope angle, aspect) and mean annual precipitation using overlay analyses. We used these data and relationships to develop a logistic regression model in order to generate maps of predicted susceptibility to defoliation by O. amphimone for each study area. Forests of N. pumilio are typically more susceptible to O. amphimone outbreaks than lower elevation forests of other Nothofagus species ( N. dombeyi and N. antarctica ). Stands located at intermediate elevations and on gentle slopes (
-
influence of fire severity on stand development of araucaria araucana Nothofagus pumilio stands in the andean cordillera of south central chile
Austral Ecology, 2010Co-Authors: Mauro E Gonzalez, Thomas T Veblen, Jason S SiboldAbstract:Fire is the prevalent disturbance in the Araucaria-Nothofagus forested landscape in south-central Chile. Although both surface and stand-replacing fires are known to characterize these ecosystems, the variability of fire severity in shaping forest structure has not previously been investigated in Araucaria-Nothofagus forests. Age structures of 16 stands, in which the ages of approximately 650 trees were determined, indicate that variability in fire severity and frequency is key to explaining the mosaic of forest patches across the Araucaria-Nothofagus landscape. High levels of tree mortality in moderate- to high-severity fires followed by new establishment of Nothofagus pumilio typically result in stands characterized by one or two cohorts of this species. Large Araucaria trees are highly resistant to fire,and this species typically survives moderate- to high-severity fires either as dispersed individuals or as small groups of multi-aged trees. Small post-fire cohorts of Araucaria may establish, depending on seed availability and the effects of subsequent fires. Araucaria's great longevity (often >700 years) and resistance to fire allow some individuals to survive fires that kill and then trigger new Nothofagus cohorts. Even in relatively mesic habitats, where fires are less frequent, the oldest Araucaria-Nothofagus pumilio stands originated after high-severity fires. Overall, stand development patterns of subalpine Araucaria-N. pumilio forests are largely controlled by moderate- to high-severity fires, and therefore tree regeneration dynamics is strongly dominated by a catastrophic regeneration mode.
-
fire history of araucaria Nothofagus forests in villarrica national park chile
Journal of Biogeography, 2005Co-Authors: Mauro E Gonzalez, Thomas T Veblen, Jason S SiboldAbstract:Aim In this study we examine fire history (i.e. c. 500 yr bp to present) of Araucaria–Nothofagus forests in the Andes cordillera of Chile. This is the first fire history developed from tree rings for an Araucaria–Nothofagus forest landscape. Location The fire history was determined for the Quillelhue watershed on the north side of Lanin volcano in Villarrica National Park, Chile. The long-lived Araucaria araucana was commonly associated with Nothofagus pumilio and N. antarctica in more mesic and drier sites respectively. Methods Based on a combination of fire-scar proxy records and forest stand ages, we reconstructed fire frequency, severity, and the spatial extent of burned areas for an c. 4000 ha study area. We used a composite fire chronology for the purpose of determining centennial-scale changes in fire regimes and comparing the pre-settlement (pre-1883) and post-settlement fire regimes. In addition, we contrasted Araucaria and Nothofagus species as fire-scar recorders. Results In the study area, we dated a total of 144 fire-scarred trees, representing 46 fire years from ad 1446 to the present. For the period from ad 1696 to 2000, using fire dates from Araucaria and Nothofagus species, the composite mean fire interval varied from 7 years for all fires to 62 years for widespread events (i.e. years in which ≥ 25% of recorder trees were scarred). Sensitivity to fire was different for Araucaria and Nothofagus species. More than 98% of the fires recorded by Nothofagus species occurred during the 1900s. The lack of evidence for older fire dates (pre-1900) in Nothofagus species was due to their shorter longevity and greater susceptibility to being killed by more severe fires. Whereas the thin-barked N. pumilio and N. antarctica are often destroyed in catastrophic fire events, large and thick-barked Araucaria trees typically survive. The spatial extent of fires ranged from small patchy events to those that burned more than 40% of the entire landscape (c. > 1500 ha). Main conclusions Fire is the most important disturbance shaping the Araucaria–Nothofagus landscape in the Araucarian region. The forest landscape has been shaped by a mixed-severity fire regime that includes surface and crown fires. High-severity widespread events were relatively infrequent (e.g. 1827, 1909 and 1944) and primarily affected tall Araucaria–N. pumilio forests and woodlands dominated by Araucaria–N. antarctica. Although there is abundant evidence of the impact of Euro-Chilean settlers on the area, the relative influence of this settlement on the temporal pattern of fire could only be tentatively established due to the relatively small number of pre-1900 fire dates. An apparent increase in fire occurrence is evident in the fire record during Euro-Chilean settlement (post-1880s) compared with the Native American era, but it may also be the result of the destruction of evidence of older fires by more recent stand-devastating fires (e.g. 1909 and 1944). Overall, the severe and widespread fires that burned in Araucaria–Nothofagus forests of this region in 2002, previously interpreted as an ecological novelty, are within the range of the historic fire regimes that have shaped this forested landscape.
-
Fire history of Araucaria–Nothofagus forests in Villarrica National Park, Chile
Journal of Biogeography, 2005Co-Authors: Mauro E Gonzalez, Thomas T Veblen, Jason S SiboldAbstract:Aim In this study we examine fire history (i.e. c. 500 yr bp to present) of Araucaria–Nothofagus forests in the Andes cordillera of Chile. This is the first fire history developed from tree rings for an Araucaria–Nothofagus forest landscape. Location The fire history was determined for the Quillelhue watershed on the north side of Lanin volcano in Villarrica National Park, Chile. The long-lived Araucaria araucana was commonly associated with Nothofagus pumilio and N. antarctica in more mesic and drier sites respectively. Methods Based on a combination of fire-scar proxy records and forest stand ages, we reconstructed fire frequency, severity, and the spatial extent of burned areas for an c. 4000 ha study area. We used a composite fire chronology for the purpose of determining centennial-scale changes in fire regimes and comparing the pre-settlement (pre-1883) and post-settlement fire regimes. In addition, we contrasted Araucaria and Nothofagus species as fire-scar recorders. Results In the study area, we dated a total of 144 fire-scarred trees, representing 46 fire years from ad 1446 to the present. For the period from ad 1696 to 2000, using fire dates from Araucaria and Nothofagus species, the composite mean fire interval varied from 7 years for all fires to 62 years for widespread events (i.e. years in which ≥ 25% of recorder trees were scarred). Sensitivity to fire was different for Araucaria and Nothofagus species. More than 98% of the fires recorded by Nothofagus species occurred during the 1900s. The lack of evidence for older fire dates (pre-1900) in Nothofagus species was due to their shorter longevity and greater susceptibility to being killed by more severe fires. Whereas the thin-barked N. pumilio and N. antarctica are often destroyed in catastrophic fire events, large and thick-barked Araucaria trees typically survive. The spatial extent of fires ranged from small patchy events to those that burned more than 40% of the entire landscape (c. > 1500 ha). Main conclusions Fire is the most important disturbance shaping the Araucaria–Nothofagus landscape in the Araucarian region. The forest landscape has been shaped by a mixed-severity fire regime that includes surface and crown fires. High-severity widespread events were relatively infrequent (e.g. 1827, 1909 and 1944) and primarily affected tall Araucaria–N. pumilio forests and woodlands dominated by Araucaria–N. antarctica. Although there is abundant evidence of the impact of Euro-Chilean settlers on the area, the relative influence of this settlement on the temporal pattern of fire could only be tentatively established due to the relatively small number of pre-1900 fire dates. An apparent increase in fire occurrence is evident in the fire record during Euro-Chilean settlement (post-1880s) compared with the Native American era, but it may also be the result of the destruction of evidence of older fires by more recent stand-devastating fires (e.g. 1909 and 1944). Overall, the severe and widespread fires that burned in Araucaria–Nothofagus forests of this region in 2002, previously interpreted as an ecological novelty, are within the range of the historic fire regimes that have shaped this forested landscape.
-
The ecology and biogeography of Nothofagus forests
Mountain Research and Development, 1998Co-Authors: Thomas T Veblen, Robert S. Hill, Jennifer ReadAbstract:Focusing on the tree species Nothofagus, or southern beech, ecologists and biogeographers here provide a comprehensive examination of the distribution, history, and ecology of this species that predominates in forests from highland New Guinea at the equator to the subantarctic latitudes of Tierra del Fuego. The Nothofagus genus offers a fascinating key to understanding historical plant geography and modern vegetation patterns.
Robert S. Hill - One of the best experts on this subject based on the ideXlab platform.
-
Nothofagus Cupules from Oligocene–Early Miocene Sediments at Balfour, Northwest Tasmania, Australia
International Journal of Plant Sciences, 2001Co-Authors: Robert S. HillAbstract:The acceptable macrofossil record of Nothofagus (Nothofagaceae) is relatively sparse, with most published records represented by poorly preserved specimens. The Tasmanian fossil record is an exception to this, with an abundance of well‐preserved Nothofagus remains. Oligocene–Early Miocene sediments near Mount Balfour in northwest Tasmania preserve cupules of five species of Nothofagus in three of the four extant subgenera. Subgenus Lophozonia is represented by Nothofagus glandularis, subgenus Nothofagus by Nothofagus bulbosa, and subgenus Brassospora by Nothofagus peduncularis and the new species Nothofagus balfourensis and Nothofagus robustus. Subgenus Lophozonia is still present in Tasmania, but subgenus Nothofagus is now restricted to South America and subgenus Brassospora to New Guinea and New Caledonia. These three subgenera have only been recorded together previously in the Early Oligocene in Tasmania. This record extends that combination, indicating a long and presumably stable ecological relations...
-
Biogeography, evolution and palaeoecology of Nothofagus (Nothofagaceae): the contribution of the fossil record
Australian Journal of Botany, 2001Co-Authors: Robert S. HillAbstract:Nothofagus is an ancient genus with a distribution that has attracted considerable interest from biogeographers. The lack of consensus among biogeographical reconstructions is probably due to emphasis being placed solely or largely on the living species. Nothofagus had a much greater distribution and diversity in the past than it has now; this makes it difficult to reconstruct its history from living species’ interrelationships and distribution. Unfortunately, the fossil record is difficult to interpret, and contains many records that convey no useful information or possibly even misinformation. However, the best fossil records of Nothofagus provide past distributions that must be explained by biogeographical hypotheses and place minimum times on evolutionary events within the genus. They also provide information on past ecological associations that are best explained by invoking extinct climates.
-
Biogeography of Nothofagus supports the sequence of Gondwana break-up
TAXON, 2001Co-Authors: Ulf Swenson, Robert S. Hill, Stephen McloughlinAbstract:The Austral biota reveals many links between Australasia and South America that have challenged biogeographers for many years. Nothofagus, the Southern Beech, is probably the classical example. With the general acceptanceof continental drift, the break-up of Gondwana is regarded as primarily responsible for many disjunct patterns expressed in the Southern Hemisphere biota. Vicariance biogeography is the principal tool used to investigate biogeographic patterns of extant plant groups, resulting in areagrams or general area cladograms. These are often at odds with current geological knowledge, and on this basis, alternative hypotheses of area relationships and geological history have, therefore, been suggested. One such areagram was recently advocated by Linder & Crisp (1995) in a biogeographic analysis of Nothofagus. Three explanations, often in combination, account for incongruence: long-distance dispersals, extinctions, and erroneous geological models. All of these parameters ought to be considered in the analysis. Here we report the result of a historical biogeographic analysis of Nothofagus where we compare the reconciled trees between a well-supported Nothofagus phylogeny and two geological hypotheses: (1) the current view of Gondwana break-up, and (2) the areagram by Linder & Crisp. Our analysis makes use of extant and extinct taxa, as well as the assumption of long-distance dispersals as defined by maximized vicariance. Our results show that Nothofagus existed prior to the break-up of Gondwana and, most importantly, its present distribution supports, and is dependent upon, the traditional break-up sequence of East Gondwana, compatible with three vicariance events. The areagram, conceived as an alternative geological hypothesis, presents a more parsimonious solution, but fails to explain numerous past distributions in areas such as Antarctica, South America, and Tasmania. We therefore recommend a conservative approach to use (general) areagrams in historical biogeography.
-
Most parsimonious areagrams versus fossils: the case of Nothofagus (Nothofagaceae)
Australian Journal of Botany, 2001Co-Authors: Ulf Swenson, Robert S. HillAbstract:Vicariance biogeography uses most parsimonious areagrams in order to explain biogeographic patterns. One notion is that areagrams convey biogeographic information to the extent that alternative palaeogeographic hypotheses are suggested. However, extinctions may distort biogeographic information, leading to areagrams showing area relationships not supported by geological data, and plausible dispersal events might also be overlooked. By the use of the software COMPONENT 2.0, Nothofagus phylogeny was reconciled with the most parsimonious areagrams. Well-preserved fossils, identified to subgenera, were optimised to the reconciled tree. Not all past distributions were predicted by the analysis, and Nothofagus has clearly been present in areas where it cannot have been if strict vicariance is followed. It can therefore be demonstrated that the biogeographic signal in Nothofagus areagrams is incomplete, and that most parsimonious areagrams can be flawed. Areagrams can be a useful tool in historical biogeography, but must be scrutinised within a known geological context and not accepted uncritically as alternative palaeogeographical hypotheses.
-
Ancestral area analysis of Nothofagus (Nothofagaceae) and its congruence with the fossil record
Australian Systematic Botany, 2000Co-Authors: Ulf Swenson, Robert S. Hill, Stephen McloughlinAbstract:The evolutionary centre of origin of Nothofagus (Nothofagaceae) remains an open question. Competing hypotheses suggest either a South American or Australasian source area for Nothofagus. Antarctica, once part of Gondwana and densely vegetated in the Cretaceous, was certainly important for the diversification of the genus but cannot be included in current modelling due to its lack of extant species. By using Bremer’s (1992), Ronquist’s (1994) and Hausdorf’s (1998) methods, all based on cladistic philosophy, analyses of the modern areas of endemism being part of the ancestral area of Nothofagus were undertaken. Southern South America was distinctly identified as the likely ancestral area by Bremer’s and Hausdorf’s methods. This result is supported by the current fossil record. Ronquist’s method was not decisive and yielded ambiguous results, suggesting a larger, combined ancestral area. These results do not favour Australasia, or parts thereof, being an important area for Nothofagus origin. Bremer’s and Hausdorf’s methods identified New Zealand as the second most plausible source area, a result partly supported by the fossil record.
Carolina Soliani - One of the best experts on this subject based on the ideXlab platform.
-
Clinal variation along precipitation gradients in Patagonian temperate forests: unravelling demographic and selection signatures in three Nothofagus spp.
Annals of Forest Science, 2020Co-Authors: Carolina Soliani, Maria Marta Azpilicueta, María Verónica Arana, Paula MarchelliAbstract:Key message Past demographic changes and current selection pressures determine the genetic variation displayed by Nothofagus species along rainfall gradients. Based on the diversity trends observed at candidate genes associated to drought stress, we inferred a differential species’ adaptive potential. Context Clinal genetic variation in natural populations could reflect either recent demographic history or the evolution of adapted genotypes along heterogeneous environments. Aims We describe genetic variation patterns in three Nothofagus species of South American temperate forests, growing along steep rainfall gradients. Our hypothesis is that the selection pressure along this gradient reinforces the genetic structure previously shaped by Pleistocene climate oscillations. Methods We screened variation along gradients at putative adaptive markers: candidate genes involved in response to drought, and EST-SSRs linked to drought stress genes. Genomic SSRs (gSSRs) were used to decouple the incidence of demographic events in the genetic structure. Results Genetic diversity at SSRs agreed with the putative location of cryptic Pleistocene refugia in Nothofagus . In addition, each species showed different trends for nucleotide diversity at candidate genes. Unbiased heterozygosity significantly correlated with precipitation at EST-SSRs in Nothofagus nervosa . We found evidences of balancing selection and several SNPs departed from neutral expectations. Conclusions Nothofagus genetic variability shows a strong imprint of demographic changes that reveals refugia location for the species during Pleistocene. This variability is modelled by environmental conditions across natural gradients, which impose selection pressure at genome regions related to stress response, providing clues about inter-specific differences in adaptive potential to water deficit.
Jason S Sibold - One of the best experts on this subject based on the ideXlab platform.
-
influence of fire severity on stand development of araucaria araucana Nothofagus pumilio stands in the andean cordillera of south central chile
Austral Ecology, 2010Co-Authors: Mauro E Gonzalez, Thomas T Veblen, Jason S SiboldAbstract:Fire is the prevalent disturbance in the Araucaria-Nothofagus forested landscape in south-central Chile. Although both surface and stand-replacing fires are known to characterize these ecosystems, the variability of fire severity in shaping forest structure has not previously been investigated in Araucaria-Nothofagus forests. Age structures of 16 stands, in which the ages of approximately 650 trees were determined, indicate that variability in fire severity and frequency is key to explaining the mosaic of forest patches across the Araucaria-Nothofagus landscape. High levels of tree mortality in moderate- to high-severity fires followed by new establishment of Nothofagus pumilio typically result in stands characterized by one or two cohorts of this species. Large Araucaria trees are highly resistant to fire,and this species typically survives moderate- to high-severity fires either as dispersed individuals or as small groups of multi-aged trees. Small post-fire cohorts of Araucaria may establish, depending on seed availability and the effects of subsequent fires. Araucaria's great longevity (often >700 years) and resistance to fire allow some individuals to survive fires that kill and then trigger new Nothofagus cohorts. Even in relatively mesic habitats, where fires are less frequent, the oldest Araucaria-Nothofagus pumilio stands originated after high-severity fires. Overall, stand development patterns of subalpine Araucaria-N. pumilio forests are largely controlled by moderate- to high-severity fires, and therefore tree regeneration dynamics is strongly dominated by a catastrophic regeneration mode.
-
fire history of araucaria Nothofagus forests in villarrica national park chile
Journal of Biogeography, 2005Co-Authors: Mauro E Gonzalez, Thomas T Veblen, Jason S SiboldAbstract:Aim In this study we examine fire history (i.e. c. 500 yr bp to present) of Araucaria–Nothofagus forests in the Andes cordillera of Chile. This is the first fire history developed from tree rings for an Araucaria–Nothofagus forest landscape. Location The fire history was determined for the Quillelhue watershed on the north side of Lanin volcano in Villarrica National Park, Chile. The long-lived Araucaria araucana was commonly associated with Nothofagus pumilio and N. antarctica in more mesic and drier sites respectively. Methods Based on a combination of fire-scar proxy records and forest stand ages, we reconstructed fire frequency, severity, and the spatial extent of burned areas for an c. 4000 ha study area. We used a composite fire chronology for the purpose of determining centennial-scale changes in fire regimes and comparing the pre-settlement (pre-1883) and post-settlement fire regimes. In addition, we contrasted Araucaria and Nothofagus species as fire-scar recorders. Results In the study area, we dated a total of 144 fire-scarred trees, representing 46 fire years from ad 1446 to the present. For the period from ad 1696 to 2000, using fire dates from Araucaria and Nothofagus species, the composite mean fire interval varied from 7 years for all fires to 62 years for widespread events (i.e. years in which ≥ 25% of recorder trees were scarred). Sensitivity to fire was different for Araucaria and Nothofagus species. More than 98% of the fires recorded by Nothofagus species occurred during the 1900s. The lack of evidence for older fire dates (pre-1900) in Nothofagus species was due to their shorter longevity and greater susceptibility to being killed by more severe fires. Whereas the thin-barked N. pumilio and N. antarctica are often destroyed in catastrophic fire events, large and thick-barked Araucaria trees typically survive. The spatial extent of fires ranged from small patchy events to those that burned more than 40% of the entire landscape (c. > 1500 ha). Main conclusions Fire is the most important disturbance shaping the Araucaria–Nothofagus landscape in the Araucarian region. The forest landscape has been shaped by a mixed-severity fire regime that includes surface and crown fires. High-severity widespread events were relatively infrequent (e.g. 1827, 1909 and 1944) and primarily affected tall Araucaria–N. pumilio forests and woodlands dominated by Araucaria–N. antarctica. Although there is abundant evidence of the impact of Euro-Chilean settlers on the area, the relative influence of this settlement on the temporal pattern of fire could only be tentatively established due to the relatively small number of pre-1900 fire dates. An apparent increase in fire occurrence is evident in the fire record during Euro-Chilean settlement (post-1880s) compared with the Native American era, but it may also be the result of the destruction of evidence of older fires by more recent stand-devastating fires (e.g. 1909 and 1944). Overall, the severe and widespread fires that burned in Araucaria–Nothofagus forests of this region in 2002, previously interpreted as an ecological novelty, are within the range of the historic fire regimes that have shaped this forested landscape.
-
Fire history of Araucaria–Nothofagus forests in Villarrica National Park, Chile
Journal of Biogeography, 2005Co-Authors: Mauro E Gonzalez, Thomas T Veblen, Jason S SiboldAbstract:Aim In this study we examine fire history (i.e. c. 500 yr bp to present) of Araucaria–Nothofagus forests in the Andes cordillera of Chile. This is the first fire history developed from tree rings for an Araucaria–Nothofagus forest landscape. Location The fire history was determined for the Quillelhue watershed on the north side of Lanin volcano in Villarrica National Park, Chile. The long-lived Araucaria araucana was commonly associated with Nothofagus pumilio and N. antarctica in more mesic and drier sites respectively. Methods Based on a combination of fire-scar proxy records and forest stand ages, we reconstructed fire frequency, severity, and the spatial extent of burned areas for an c. 4000 ha study area. We used a composite fire chronology for the purpose of determining centennial-scale changes in fire regimes and comparing the pre-settlement (pre-1883) and post-settlement fire regimes. In addition, we contrasted Araucaria and Nothofagus species as fire-scar recorders. Results In the study area, we dated a total of 144 fire-scarred trees, representing 46 fire years from ad 1446 to the present. For the period from ad 1696 to 2000, using fire dates from Araucaria and Nothofagus species, the composite mean fire interval varied from 7 years for all fires to 62 years for widespread events (i.e. years in which ≥ 25% of recorder trees were scarred). Sensitivity to fire was different for Araucaria and Nothofagus species. More than 98% of the fires recorded by Nothofagus species occurred during the 1900s. The lack of evidence for older fire dates (pre-1900) in Nothofagus species was due to their shorter longevity and greater susceptibility to being killed by more severe fires. Whereas the thin-barked N. pumilio and N. antarctica are often destroyed in catastrophic fire events, large and thick-barked Araucaria trees typically survive. The spatial extent of fires ranged from small patchy events to those that burned more than 40% of the entire landscape (c. > 1500 ha). Main conclusions Fire is the most important disturbance shaping the Araucaria–Nothofagus landscape in the Araucarian region. The forest landscape has been shaped by a mixed-severity fire regime that includes surface and crown fires. High-severity widespread events were relatively infrequent (e.g. 1827, 1909 and 1944) and primarily affected tall Araucaria–N. pumilio forests and woodlands dominated by Araucaria–N. antarctica. Although there is abundant evidence of the impact of Euro-Chilean settlers on the area, the relative influence of this settlement on the temporal pattern of fire could only be tentatively established due to the relatively small number of pre-1900 fire dates. An apparent increase in fire occurrence is evident in the fire record during Euro-Chilean settlement (post-1880s) compared with the Native American era, but it may also be the result of the destruction of evidence of older fires by more recent stand-devastating fires (e.g. 1909 and 1944). Overall, the severe and widespread fires that burned in Araucaria–Nothofagus forests of this region in 2002, previously interpreted as an ecological novelty, are within the range of the historic fire regimes that have shaped this forested landscape.
