Interacting global change drivers suppress a foundation tree species

Ecological stress caused by climate change, invasive species and anthropogenic disturbance is driving global environmental change, but how these stressors interact to impact native species are poorly understood. We used a field experiment to test how two stressors (drought and plant invasion by Imperata cylindrica) interacted to determine the effects of a third stressor (fire) on a foundation tree species (Pinus palustris). The invasion combined with prolonged drought resulted in shorter trees than invasion alone. The invasion also resulted in 65% greater fuel loads, four times taller flames, greater maximum temperatures and longer heating duration. Consequently, nearly all tree mortality occurred due to a synergistic interaction between the drought + invasion treatment and fire, where invasion caused taller flames that impacted trees that were shorter due to drought. These findings demonstrate that synergy amongst ecological stressors can dramatically impact native species, with significant implications for forecasting the effects of multiple stressors under global change.

Automated summary

Ecological stressors such as climate change, invasive species, and human disturbance can interact to impact native species. A field experiment was conducted to examine the interactions between drought, plant invasion, and fire on a foundation tree species. It was found that the combination of invasion and drought resulted in shorter trees and increased fuel loads, flame height, maximum temperatures, and heating duration. The mortality of trees was mainly caused by a synergistic interaction between drought, invasion, and fire. These findings highlight the significant implications of synergistic interactions among stressors for predicting the effects of multiple stressors under global change.