Patterns and drivers of Araucaria araucana forest growth along a biophysical gradient in the northern Patagonian Andes: Linking tree rings with satellite observations of soil moisture

Authors

  • Ariel A. Muñoz,

    Corresponding author
    1. Centro de Tecnologías Ambientales, Universidad Técnica Federico Santa María, Valparaíso, Chile
    2. Laboratorio de Dendrocronología y Cambio Global, Instituto de Conservación Biodiversidad y Territorio, Facultad de Ciencias Forestales y Recursos Naturales, Universidad Austral de Chile, Valdivia, Chile
    3. Centro de Estudios Ambientales (CEAM), Universidad Austral de Chile, Valdivia, Chile
    • Corresponding author.

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  • Jonathan Barichivich,

    1. Climatic Research Unit (CRU), School of Environmental Sciences, University of East Anglia, Norwich, UK
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  • Duncan A. Christie,

    1. Laboratorio de Dendrocronología y Cambio Global, Instituto de Conservación Biodiversidad y Territorio, Facultad de Ciencias Forestales y Recursos Naturales, Universidad Austral de Chile, Valdivia, Chile
    2. Center for Climate and Resilience Research [CR]2, Chile
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  • Wouter Dorigo,

    1. Institute of Photogrammetry and Remote Sensing, Vienna University of Technology, Vienna, Austria
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  • David Sauchyn,

    1. Prairie Adaptation Research Collaborative (PARC), University of Regina, Regina, Canada
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  • Álvaro González-Reyes,

    1. Laboratorio de Dendrocronología y Cambio Global, Instituto de Conservación Biodiversidad y Territorio, Facultad de Ciencias Forestales y Recursos Naturales, Universidad Austral de Chile, Valdivia, Chile
    2. Departamento de Geología, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Santiago, Chile
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  • Ricardo Villalba,

    1. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales (IANIGLA), CONICET, Mendoza, Argentina
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  • Antonio Lara,

    1. Laboratorio de Dendrocronología y Cambio Global, Instituto de Conservación Biodiversidad y Territorio, Facultad de Ciencias Forestales y Recursos Naturales, Universidad Austral de Chile, Valdivia, Chile
    2. Center for Climate and Resilience Research [CR]2, Chile
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  • Natalia Riquelme,

    1. Laboratorio de Dendrocronología y Cambio Global, Instituto de Conservación Biodiversidad y Territorio, Facultad de Ciencias Forestales y Recursos Naturales, Universidad Austral de Chile, Valdivia, Chile
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  • Mauro E. González

    1. Laboratorio de Dendrocronología y Cambio Global, Instituto de Conservación Biodiversidad y Territorio, Facultad de Ciencias Forestales y Recursos Naturales, Universidad Austral de Chile, Valdivia, Chile
    2. Center for Climate and Resilience Research [CR]2, Chile
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Abstract

Araucaria araucana (Araucaria) is a long-lived conifer growing along a sharp west–east biophysical gradient in the Patagonian Andes. The patterns and climate drivers of Araucaria growth have typically been documented on the driest part of the gradient relying on correlations with meteorological records, but the lack of in situ soil moisture observations has precluded an assessment of the growth responses to soil moisture variability. Here, we use a network of 21 tree-ring width chronologies to investigate the spatiotemporal patterns of tree growth through the entire gradient and evaluate their linkages with regional climate and satellite-observed surface soil moisture variability. We found that temporal variations in tree growth are remarkably similar throughout the gradient and largely driven by soil moisture variability. The regional spatiotemporal pattern of tree growth was positively correlated with precipitation (r = 0.35 for January 1920–1974; P < 0.01) and predominantly negatively correlated with temperature (r = −0.38 for January–March 1920–1974; P < 0.01) during the previous growing season. These correlations suggest a temporally lagged growth response to summer moisture that could be associated with known physiological carry-over processes in conifers and to a response to moisture variability at deeper layers of the rooting zone. Notably, satellite observations revealed a previously unobserved response of Araucaria growth to summer surface soil moisture during the current rather than the previous growing season (r = 0.65 for 1979–2000; P < 0.05). This new response has a large spatial footprint across the mid-latitudes of the South American continent (35°–45°S) and highlights the potential of Araucaria tree rings for palaeoclimatic applications. The strong moisture constraint on tree growth revealed by satellite observations suggests that projected summer drying during the coming decades may result in regional growth declines in Araucaria forests and other water-limited ecosystems in the Patagonian Andes.

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