Survival, growth and vulnerability to drought in fire refuges: implications for the persistence of a fire-sensitive conifer in northern Patagonia
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Fire severity and extent are expected to increase in many regions worldwide due to climate change. Therefore, it is crucial to assess the relative importance of deterministic vs. stochastic factors producing remnant vegetation to understand their function in the persistence of fire-sensitive plants. Vegetation remnants (areas within the landscape that have not burned for a considerable amount of time) may occur stochastically or in more predictable locations (fire refuges) where physical conditions decrease fire severity. Our aim was to determine if remnant forests of the fire-sensitive conifer Austrocedrus chilensis are associated with biophysical attributes that allow persistence in a fire-prone Patagonian landscape. We conducted a multi-scale approach, determining attributes of forest remnants and their surroundings (matrices) through remote sensing and field-based biophysical and functional characteristics, and quantifying how tree survival probability relates to microsite conditions. Trees within remnants displayed abundant fire scars, were twofold older and had threefold larger growth rates than matrix trees. Remnants were associated with high rocky cover and elevated topographical positions. Tree survival increased in hilltops, eastern aspects, and with sparse vegetation. Trees within remnants experienced severe reductions in growth during droughts. Our results suggest that A. chilensis remnants are mainly the result of refuges, where environmental conditions increase fire survival, but also increase susceptibility to drought. A trade-off between fire survival and drought vulnerability may imply that under increasing drought and fire severity, locations that in the past have served as refuges may reduce their ability to allow the persistence of fire-sensitive taxa.
KeywordsBasal area increment Forest remnant Climate change Biophysical attributes Austrocedrus chilensis
We thank Juan Manuel Morales for insightful comments on the manuscript and Maria Laura Suarez for her help in the tree chronology and correlation function analysis. We especially thank Jeremy Lichstein (handling editor) and two anonymous reviewers for their comments which greatly improved the quality of the manuscript. This study was funded by grant BIRF 7520 (Sustainable Forests Plantations Component) PIA 10058 and PIA 12055 (Ministerio de Agricultura, Ganadería y Pesca). J.B.L. acknowledges a CONICET fellowship.
Author contribution statement
J.B.L. performed the research, conducted fieldwork, analyzed the data and wrote the manuscript. J.B.L., J.H.G. and T.K. conceived and designed the study. L.A.G. contributed to the data analysis.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest and that the experiments comply with the current laws of Argentina, where the experiments were performed.
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