Austrocedrus chilensis mortality in the Nahuel Huapi National Park (Argentina)

Baccalá, Nora; Rosso, Pablo; Havrylenko, Maria

doi:10.1016/s0378-1127(98)00250-3

Cited by 31 publications

(33 citation statements)

References 11 publications

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“…Sites at high risk of disease occurrence were associated with variables that suggest wet soils, and this finding agrees with previous abiotic studies related to the disease (Baccalá et al 1998;La Manna and Rajchenberg 2004a, b;La Manna et al 2008c) and with pathology studies reporting P. austrocedrae as the biotic causal agent of A. chilensis disease Hansen 2009, 2010). Wet soils are a very important factor for increasing severity and spread of several Phytophthora species (Erwin and Ribeiro 1996).…”

Section: Site Features and Disease Risksupporting

confidence: 89%

“…Phytophthora austrocedrae is an aquatic mould that requires water for dispersion and penetrates the plant through the roots (Greslebin et al 2007). Many Phytophthora species are generally associated with wet soils, and the A. chilensis disease has been associated with wet soils in studies carried out at different scales (Baccalá et al 1998;La Manna and Rajchenberg 2004a, b;La Manna et al 2008a). The geographic origin of P. austrocedrae is a very important issue that needs to be resolved through phylogenetic studies, since it is yet unknown whether it is a native or an introduced pathogen (Greslebin and Hansen 2009).…”

Section: Introductionmentioning

confidence: 99%

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Modelling Phytophthora disease risk in Austrocedrus chilensis forests of Patagonia

2011

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Austrocedrus chilensis forests suffer from a disease caused by Phytophthora austrocedrae, which is found often in wet soils. We applied three widely used modelling techniques, with different data requirements, to model disease potential distribution under current environmental conditions: Mahalanobis distance, Maxent and Logistic regression. Each model was built using field data of health condition and landscape layers of environmental conditions (distance to streams, slope, aspect, elevation, mean annual precipitation and soil pH NaF). We compared model predictions by area under the receiver operating characteristic curve and Kappa statistics. A reasonable ability to predict observed disease distribution was found for each of the three modelling techniques. However, Maxent and Logistic regression presented the best predictive performance, with significant differences with respect to the Mahalanobis distance model. Our results suggested that if good absence data are available, Logistic regression should be used in order to better discriminate sites with high risk of disease. On the other hand, if absence data are not available or doubtful, Maxent could be a very good option. The three models predicted that around 50% (49-56%) of the currently asymptomatic forests are located on sites at risk of disease according to abiotic factors. Most of these asymptomatic forests surround the current diseased patches, at distances lower than 100 m from diseased patches. Management considerations and the scope of future studies were discussed in this article.

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Section: Site Features and Disease Risksupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Modelling Phytophthora disease risk in Austrocedrus chilensis forests of Patagonia

2011

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“…Existen evidencias de que los síntomas de decaimiento de esta especie también son más frecuentes en áreas con elevada precipitación y baja altitud (Baccalá et al 1998). Además, el crecimiento de los árboles en condiciones hídricas no limitantes puede mostrar una respuesta negativa a la precipitación, como ha sido observado en coníferas bajo clima húmedo (Mäkinen et al 2002, Rozas et al 2013.…”

Section: Discussionunclassified

Factores climáticos que controlan el crecimiento radial y la formación de fluctuaciones de densidad en la madera de Austrocedrus chilensis en Valdivia, Chile

2016

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Factores climáticos que controlan el crecimiento radial y la formación de fluctuaciones de densidad en la madera de Austrocedrus chilensis en Valdivia, Chile Tree-ring widths and intrannual wood density fluctuations (IADFs) are sound proxies of the environmental factors that control the growth of forest tree species. In this work we evaluated the impact of climate on radial growth and IADFs formation in an Austrocedrus chilensis plantation in Valdivia, Chile. We calculated mean tree-ring chronology and the annual distribution of IADFs frequency from 20 trees, and we studied their relationships with local precipitation, temperature, and large-scale El Niño-Southern Oscillation (ENSO) and Antarctic Oscillation (AO) climatic teleconnections in the period 1975-2010. We used correlation and multiple linear regression analyses to assess the climate-growth relationships and t test for means comparison to check for differences between years with and without IADFs. We observed an inverse relationship of growth with previous summer precipitation and maximum temperature during the growing period, which suggests physiological stress for trees caused by water surplus and warm summer conditions. Years with maximum IADFs frequency were those coinciding with El Niño events, which caused dry and warm summer conditions in the study area, followed by rainy conditions in September. We did not find statistically significant relationships with AO. The interaction between local climatic conditions and ENSO variation controlled IADFs formation in the wood of A. chilensis in Valdivia.Key words: Valdivian climate, wood anatomy, dendrochronology, ENSO, rainfall. RESUMENEl ancho de los anillos de crecimiento y las fluctuaciones intra-anuales de densidad de la madera (IADF) contienen información sobre los factores ambientales que controlan el desarrollo de las especies forestales. En este trabajo se evaluaron los efectos del clima sobre el crecimiento radial y la formación de IADF en una plantación de Austrocedrus chilensis en Valdivia, Chile. Se calcularon la cronología media de crecimiento radial y la distribución anual de frecuencias de IADF de 20 árboles y se estudió su relación con la precipitación, la temperatura y los índices de El Niño Oscilación del Sur (ENSO) y Oscilación Antártica (AO) en el período 1975-2010. Se utilizaron análisis de correlación y regresión múltiple para estudiar la relación crecimiento-clima y la prueba t de comparación de medias para contrastar diferencias entre años con y sin IADF. Se observó una relación inversa del crecimiento con la precipitación del verano previo y la temperatura máxima durante el período de crecimiento, evidenciando condiciones de estrés por exceso de precipitación y elevadas temperaturas estivales. Los años con máxima frecuencia de IADF en la madera de A. chilensis fueron aquellos en que se produjo un episodio El Niño, que en el área de estudio causa veranos secos y cálidos, seguidos por un mes de septiembre lluvioso. No se observaron relaciones significativas con AO. La interacción en...

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“…Reported about 60 years ago (Hranilovic 1988), this spatially erratic process of overstory mortality is presently found across the range of distribution of A. chilensis in Argentina. Thus, the mortality occurring in cypress forests develops slowly in individual trees (Calí 1996) and cannot be explained by only a single factor but rather a complex interaction of biotic (Greslebin et al 2007) and abiotic factors (Baccalá et al 1998;La Manna and Rajchenberg 2004;La Manna et al 2008a) has lead to the idea that 'mal del cipre´s' is a type of forest decline (Baccalá et al 1998;Filip and Rosso 1999;La Manna and Rajchenberg 2004).…”

Section: Introductionmentioning

confidence: 99%

Can a natural experiment be used as a tool to design partial cutting regimes? The decline of Austrocedrus chilensis forests, an example

Amoroso

Larson

2010

Journal of Forest Research

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The forests of Austrocedrus chilensis in Argentina suffer mortality from what is locally known as 'mal del cipre´s'. This disturbance usually appears as aggregations of dead trees of varying sizes. The mortality process seems unpredictable, and regeneration establishment is variable under these conditions. The highly variable mortality rates results in a natural experiment that allows the correlation of overstory mortality with regeneration rate. This correlation should then make it possible to estimate the regeneration success which would follow after different levels of partial cutting, allowing the purposeful direction of the regeneration process. We collected data from eight Austrocedrus chilensis-dominated stands and reconstructed overstory mortality over time and correlated it to the regeneration recruitment. Mortality showed two patterns: increasing 'continuous' mortality over time, and 'pulses' of important basal area loss in short periods. Overstory mortality had an effect on the recruitment and composition of the regeneration by allowing different species establishment depending on the degree of mortality. By quantifying mortality basal area and recruitment over time, we calculated estimates that can provide partial cutting guidance. Partial cuttings would then allow the purposeful direction of the regeneration process. Stand reconstruction studies provided a useful tool to help designing regeneration systems using a natural experiment. Some specific management implications for symptomatic A. chilensis forests are given.

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Austrocedrus chilensis mortality in the Nahuel Huapi National Park (Argentina)

Cited by 31 publications

References 11 publications

Modelling Phytophthora disease risk in Austrocedrus chilensis forests of Patagonia

Modelling Phytophthora disease risk in Austrocedrus chilensis forests of Patagonia

Factores climáticos que controlan el crecimiento radial y la formación de fluctuaciones de densidad en la madera de Austrocedrus chilensis en Valdivia, Chile

Can a natural experiment be used as a tool to design partial cutting regimes? The decline of Austrocedrus chilensis forests, an example

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