Pest management in future climates: Warming reduces physical weed management effectiveness
Summary
Climate warming could cause invasive plants to grow more quickly, altering the effectiveness of current management strategies. However, this phenomenon remains relatively understudied. Keller & Shea (2002) analyzed the effects of warming on the growth of the invasive weed, musk thistle (Carduus nutans) and compared the effectiveness of mowing for controlling musk thistle populations under ambient and warmed conditions. The authors also tested three mowing treatments on the ambient and warmed thistle - an early mow (when thistle were 40 cm), a middle mow (1 week later), and a late mow (2 weeks later). Musk thistle in elevated temperatures flowered earlier, grew taller, and produced more seed heads for reproduction. Late mowing was the most effective treatment in both ambient and elevated temperatures, but mowing was found to be less effective in controlling the musk thistle under warmer temperatures. With warming, musk thistle were more likely to survive mowing and grow tall enough to effectively spread their seeds such that invasive populations would grow. With climate change, these findings suggest that increased mowing frequency will be needed to control thistle populations.
Take home points
Warming significantly increased projected local population growth under all mowing treatments
Warming caused mowing treatments to be less effective in reducing musk thistle performance
Management implications
Given more rapid weed growth rates and longer growing seasons, it is likely that more mowing treatments will be needed to keep invasive plant populations from growing
Mowing late in the thistle’s growing season was found to be the most effective in reducing survival probability of the plant, plant height, and seed production
Keywords
Management efficacy; Carduus nutans; Climate change; Integral projection model; Mechanical weed management