Abstract Detail



Ecology

Crandall, Raelene [1], Knight, Tiffany [2].

Invasive shrub increases forest resilience to drought and fire disturbances.

One of the most critical challenges in the 21st century is promoting ecosystem resilience to novel disturbances. Ecosystem resilience is fundamental to sustaining biodiversity, ecosystem services, and human well-being. However, global changes and invasion of exotic species are altering ecosystems and disturbance regimes in ways that may erode resilience and lead to novel trajectories. The objective of this research was to examine the resilience of native forest communities to the interactive effects of invasion by an exotic species, drought, and fire.  We measured vital rates and modeled population growth of two native shrubs and one coexisting invasive shrub, Lonicera maackii, in a Midwestern U.S.A. oak-hickory forest over three growing seasons: before, during, and after a drought. Treatment plots (fire x invasive shrub) were replicated three times in sites with and without removal of the invasive shrub and half of the plots were burned during the drought year using prescribed fire. Overall, burning had no significant effect on the population growth rate of the invasive shrub, but negatively affected both of the natives. We found that the invasive shrub had significantly higher survival than either of the native species. It also had a different mode of post-fire regeneration; the native shrubs resprouted from root crowns and the invasive resprouted from aerial buds. Lonicera maackii has been shown to outcompete native plants by blocking light attenuation; it grows quickly, and its branches spread, allowing very little light to reach the forest floor. We expected burning to enhance this advantage because L. maackii is able to maintain its location in the shrub canopy while native species become restricted to the shrub understory. In contrast, we found that regardless of the presence of fire, species richness was higher during and after drought where the invasive species was present. Furthermore, multivariate analyses show that the plant community composition was more resilient after multiple disturbances when the invasive was present. We suggest that the invasive shrub created shaded, mesic microsites during drought, thereby promoting native species survival. These results highlight the potential benefit of an invasive species to the resilience of ecosystems that experience multiple, interacting disturbances.


1 - University Of Florida, School Of Forest Resources And Conservation, P.O. Box 110410, Gainesville, FL, 32611, United States
2 - Martin Luther University Halle-Wittenberg, Am Kirchtor 1, Halle (Saale), 06108, Germany

Keywords:
none specified

Presentation Type: Poster Time and date to be determined
Number: PEC016
Abstract ID:645
Candidate for Awards:None


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