Abstract

RODRIGUEZ-CATON, Milagros  and  VILLALBA, Ricardo. Indicators of forest decline for Nothofagus pumilio in northern Patagonia, Argentina. Madera bosques [online]. 2018, vol.24, n.2, e2421588.  Epub May 17, 2018. ISSN 2448-7597.  https://doi.org/10.21829/myb.2018.2421588.

Forest decline is associated with partial or total crown mortality in a large percentage of trees at the stand level. While forest decline has been reported on a global context, the relationships between the external conditions of trees and their radial growth have rarely been reported. This study relates the intensity of decline with radial growth in 294 Nothofagus pumilio trees in northern Patagonia. The selected external indicators of decline were crown mortality, bark health, the incidence of boring insects and woodpeckers, as well as the presence of hemiparasite plants, fungi and lichens. High percentages of crown mortality are significantly related to decreasing radial growth of remaining trees. This relationship is more reliable when basal area increments rather than ring widths are used as estimates of radial growth. Bark health and abundance of cavities, resulting from the activities of boring insects and woodpeckers, were also significantly inversely related to growth. In contrast, no statistically significant relationships were found between growth and the presence of hemiparasites, fungi or lichens. Based on these results, we recommend the use of the following external indicators (1) crown mortality, (2) bark conditions and (3) cavities from boring insects and/or woodpeckers, to comprehensively characterize the Nothofagus pumilio forest decline in Patagonia.

Keywords : growth rings; wood-boring insects; crown mortality; woodpeckers; forest health.

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