Using assembly rules to measure the resilience of riparian plant communities to beaver invasion in subantarctic forests

Wallem, P.K., C.R. Anderson, G. Martinez-Pastur, and M.V. Lencinas. 2010. Using assembly rules to measure the resilience of riparian plant communities to beaver invasion in subantarctic forests. Biological Invasions 12:325-335.

In the 1940s North American beavers were introduced to Tierra del Fuego, an area shared by Chile and Argentina. Their populations have increased dramatically with no natural predators and a plentiful food supply. Wallem et al compared sites in Chile and Argentina that a) are currently inhabited by beavers, b)were at one point inhabited by beavers, and c)never were inhabited by beavers to assess if any of these disturbed communities were resilient to the disturbance. They found that upon introduction, beavers set these communities on a different trajectory and even after 20 years of beaver removal a community did not return to its initial state.

This paper provides a good example of how researchers often use observational data along a natural gradient to infer an alternate state without empirically testing for it. While they didn’t actually test any of the assembly rules within this system (a little misleading given the title), they did use the theory to provide an explanation as to why these systems were not recovering after disturbance.

Toward the end of class last week, we began discussing the usefulness of resilience in restoration. By the end, it still wasn’t clear how it could be applied. This paper helped me realize that there is a multiple step process to enhancing the resilience of a community. We must first check to see if there is a community resilient to the disturbance, before we can identify the mechanisms that may contribute to this resilience and inform managers of potential active restoration programs.