congresos y reuniones científicas
Positive outcomes between herbivore diversity and tree survival: effects of management on a Patagonian forest
Congreso; XXV IUFRO World Congress; 2019
Institución organizadora:
Sustainable forest management aims to enhance biodiversity and tree productivity. However, trade-offs may exist between these objectives, such as when insect diversity and associated herbivory decreases tree growth and survival. In addition, biodiversity and tree productivity can show non-linear responses to management intensity, making applied recommendations even more challenging. We studied the effects of thinning intensity on leaf damage diversity (as a proxy of insect folivore diversity), leaf damage frequency, growth and survival of planted trees in a north Patagonian shrubland (Argentina). We randomly applied four levels of thinning intensity (0, 30, 50, and 70% of basal cover removal) to experimental plots, and followed the responses during two years. Generalized mixed-effects models were estimated for each response variable. Leaf damage diversity and frequency showed non-linear responses to thinning, both increasing at intermediate thinning intensities. Such responses were consistent for contrasting feeding guilds, different diversity indexes, and during the two study years. Despite greater leaf damage (around 45% of the leaves were damaged), plant survival also showed a non-linear response to thinning, with higher values at intermediate thinning intensities during the two years. Similarly, planted trees grew more at intermediate thinning intensities, but only during the second year (tree growth increased linearly with thinning intensity during the first year). In north Patagonian shrublands, trees may face less competition for light and soil resources at intermediate thinning intensities, while at high thinning intensities water stress typical of dry Patagonian summers could reduce tree survival. Such benefits were not offset by the greater leaf damage observed at intermediate thinning intensities. Therefore, certain intermediate levels of forest management can provide the double service of increasing arthropod biodiversity and maximizing tree survival and growth.