What Drives Exotic Species to Outcompete Natives?

Background

Understanding how attributes and performance of invasive species influence their invasion success and how invasive species interact with natives under different environmental regimes is difficult but critical to predict patterns and processes of biological invasion and to improve management.

 

Past Research

Based on long-term field data, I was able to understand the underlying ecological mechanisms of exotic species response to a biocontrol treatment. I then applied an individual-based forest model to project the biocontrol effect on exotic species dynamics and native species recovery in two wetland habitats. Zhang et al. Landscape Ecology 2017. Moreover, I developed a process-based model to estimate the optimal control strategy for invasive species in spatially heterogeneous environments. Zhang et al. Biological Control 2018. See more details here.

 

Current Research

Main collaborators: Yingdan Yuan (Nanjing Forestry University), Lele Shu (UC Davis), Edwin Grosholz (UC Davis), Alan Hastings (UC Davis), Yuxi Guo (University of Florida), James Cuda (University of Florida) Jiangxiao Qiu (University of Florida)

Recently, I started to work with the cogongrass (Imperata cylindrica), which is considered one of the most damaging in the world. This project aims to provide  a more comprehensive and mechanistic understanding of how invasive species respond to unfavorable conditions (water and nutrient stress).

 

Major Findings

​Both the mesocosm experiment and species distribution model found that cogongrass was more sensitive to water stress but not to the nutrient stress. We further found that cogongrass did not show storage effect under environmental stress, instead, it produced similar tissue quality (both foliage and root) to compensate for the less biomass production, especially under the low water condition. Lastly, the new reproduction of cogongrass was further affected by the prior water stress. Contrary to previous understanding that nutrient enrichment could facilitate biological invasion, this study highlighted the possibility that water stress may have a stronger effect on some invasive species, such as cogongrass.

 

We are analyzing the soil microbial data and we will keep you updated.