Abstract Detail

Conservation Biology

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

Positive frequency dependence and disturbance frequency determine restoration success using fire.

Exotic species can often invade and subsequently dominate native communities, particularly when the disturbance regime of the native habitat has been significantly altered. For example, in many areas throughout the world, humans have altered the fire regime in natural communities (typically by fire suppression). This often leads to an alternative stable state with a community dominated by non-native, invasive species. Restoration projects that re-introduce the native fire regime have experienced mixed success on whether or not the community returns to its native state. Here, we provide a synthetic framework that can predict why some communities are easier to restore than others based on three factors: (1) fitness of native vs. invasive species following fire, (2) density and aggregation of the invasive species pre-restoration and (3) the strength of positive frequency dependence (PFD) of the invasive species. Most invasive plants exhibit PFD resulting from allelopathy, plant-soil feedbacks, and ecosystem engineering. We predict communities will be easy to restore with fire if the invasive species has low survivorship following fire, if the invasive species occurs at low density and low aggregation, and if the strength of PDF is low. We used an individual-based, simulation model to determine the outcome of competition between a fire-adapted native and non-fire-adapted invasive species after accounting for initial density and aggregation of invasive species, strength of PFD, and disturbance frequency. We found that disturbances result in native species dominating a community, but only if the strength of PFD is low, fires are frequent, and/or invasive species are not initially dominant with a clumped distribution in the community. As the strength of the PFD increases and fire frequency decreases, the community gradually moves from one dominated by natives to one dominated by invasives, but only if the initial density is low. When the initial density of invasive species is above 20% with a clumped distribution, restoration using fire will only be successful if fires are very frequent and the invasive species does not exhibit PFD. These results indicate it is critical to consider the role of PFD before reintroducing disturbances to degraded systems. When the strength of PFD is high and invasives are dominant and/or clumped within a community, multiple restoration strategies are likely necessary.

Broader Impacts:

1 - Washington University - St. Louis, Department of Biology And Tyson Research Center, Box 1137, St. Louis, MO, 63130, USA
2 - Washington University - St. Louis, Department of Biology and Tyson Research Center, St. Louis, MO, 63130, USA

Keywords:
Postive frequency dependence
invasive species
fire
restoration.

Presentation Type: Oral Paper:Papers for Topics
Session: 30
Location: Marlborough A/Riverside Hilton
Date: Tuesday, July 30th, 2013
Time: 2:00 PM
Number: 30003
Abstract ID:855
Candidate for Awards:None