Alien Plant Invasion in Mixed-Grass Prairie: Effects of Vegetation Type and Anthropogenic Disturbance

Abstract

The ability of alien plant species to invade a region depends not only on attributes of the plant, but on characteristics of the habitat being invaded. Here, we examine characteristics that may influence the success of alien plant invasion in mixed-grass prairie at Theodore Roosevelt National Park, in western North Dakota, USA. The park consists of two geographically separate units with similar vegetation types and management history, which allowed us to examine the effects of native vegetation type, anthropogenic disturbance, and the separate park units on the invasion of native plant communities by alien plant species common to counties surrounding both park units. If matters of chance related to availability of propagules and transient establishment opportunities determine the success of invasion, park unit and anthropogenic disturbance should better explain the variation in alien plant frequency. If invasibility is more strongly related to biotic or physical characteristics of the native plant communities, models of alien plant occurrence should include vegetation type as an explanatory variable. We examined Ͼ1300 transects across all vegetation types in both units of the park. Akaike's Information Criterion (AIC) indicated that the fully parameterized model, including the interaction among vegetation type, disturbance, and park unit, best described the distribution of both total number of alien plants per transect and frequency of alien plants on transects where they occurred. Although all vegetation types were invaded by alien plants, mesic communities had both greater numbers and higher frequencies of alien plants than did drier communities. A strong element of stochasticity, reflected in differences in frequencies of individual species between the two park units, suggests that prediction of risk of invasion will always involve uncertainty. In addition, despite well-documented associations between anthropogenic disturbance and alien plant invasion, five of the six most abundant alien species at Theodore Roosevelt National Park had distributions unrelated to disturbance. We recommend that vegetation type be explicitly taken into account when designing monitoring plans for alien species in natural areas.

The mammalian communities in coffee plantations around a protected area in the Western Ghats, India

“…There is evidence linking ecosystem invasibility to disturbance: more disturbed ecosystems are more vulnerable to invasions by alien species than less disturbed ones (e.g., Myers 1983;Hobbs 1989;Larson et al 2001).…”

Insect visitation and pollen deposition in an invaded prairie plant community

“…The south unit of the park was established in 1947 and contains freeranging native ungulates as well as a small herd of wild horses. More detail on plant species associations within the park can be found in Larson et al (2001). E. esula was first documented in the South Unit of TRNP in 1970 (unpublished park documents).…”

“…Using data from a 1996 stratified-random survey of plants in the South Unit in which >800 geo-referenced transects were examined (methods for the survey can be found in Larson et al (2001)), we identified areas within the South Unit that were likely to have one of several concurrently blooming native plants, either >100 m away from or within a Euphorbia infestation. We avoided the dwarf sagebrush (Artemesia cana) and river bottom vegetation types because they harbor large populations of a variety of non-native species (Larson et al, 2001).…”

“…We avoided the dwarf sagebrush (Artemesia cana) and river bottom vegetation types because they harbor large populations of a variety of non-native species (Larson et al, 2001). All sampling was done in upland prairie to minimize bias in insect habitat characteristics that could be associated with infested versus non-infested habitats.…”

Effects of Disturbance Associated with Natural Gas Extraction on the Occurrence of Three Grassland Songbirds

“…In addition to this, traffic noise can decrease abundance and breeding activity near roads (Reijen et al 1996, Forman et al 2002, Ingelfinger and Anderson 2004. Soil disturbance caused by traffic along offroad trails can lead to invasion by non-native plant species (Trombulak and Frissell 2000, Larson et al 2001, von der Lippe and Kowarik 2007B. Smith, unpublished manuscript).…”