Understanding the impact of projected temperature increase on plant performance and plant-herbivore interactions at managed native tree plantations in northern Patagonia

Abstract

Forest management must adapt to both current and future climate changes. There is limited knowledge regarding techniques to enhance the performance of planted trees and their interactions amidst rising temperatures and drought. We studied the effects of rising temperatures and woodland harvesting intensities (WHI) on planted trees and their herbivores in a Patagonian woodland. We planted six native timber species at various WHI levels (0%, 30%, 50%, and 70%) and constructed individual open-top chambers around the planted trees. The experimental increase in temperature created a warmer microenvironment for both the plants and associated herbivores, averaging a 1.4°C rise in air temperature. Additionally, WHI contributed to increased air temperature (raising 3°C from 0% to 70% harvest), radiation (760%), and annual frosts (37%). While plant survival improved with the temperature increase across the WHI levels, plant growth remained unaffected. Interestingly, although temperature was a crucial environmental factor, the temperature increase resulting from higher WHI did not specifically benefit the plants or herbivores. However, the experimental temperature rise led to reduced herbivory rates and changes in diversity patterns across WHI levels. Our findings suggest that a slight increase in temperature could buffer the effects of harvesting intensities, potentially enhancing the survival of planted trees, particularly when a significant portion of vegetation remains (30%-50% WHI). Therefore, our results indicate that these combined management practices (i.e., plantation and harvesting intensities) could remain effective in the context of a warming future scenario.