Biology Reference
In-Depth Information
It appeared that site factors such as soil nutrients and native plant species cover
were the most important factors in the post-burn landscape. Thus, this example
highlights the importance of knowing the site-specific characteristics where the
treatments have succeeded and where they have failed (e.g., what works where).
Biological control programs like the one in Theodore Roosevelt National Park
to control leafy spurge (
Euphorbia esula
) are another common management prac-
tice. The Park, like many other management groups, has also invested a lot of
money and time into herbicide applications. Effectiveness of the two different con-
trol methods over a period of three years showed that the benefits of herbicide
treatments were short term compared with those from biological control and that
herbicide treatments appeared to have a negative effect on the biological control
organisms (Larson et al. 2007). These data inform management strategies in the
Park. All of these examples indicate the importance of long-term monitoring of
management actions to determine the long-term success or failure to achieve
desired results. The results of the long-term monitoring can then be used to guide
future control efforts.
6.4.3 EcosystemChanges
Ecosystems are not static, especially with current anthropogenic impacts. These
impacts vary widely from those at the global to regional scale, ranging from large
scale effects of climate change and nitrogen deposition to local scale impacts such
as construction of a new road. A large scale effect can be predicted for smooth
brome (
Bromus inermis
) across the central grasslands of North America (Vinton
and Goergen 2006). Analysis of this species spread indicated a competitive advan-
tage over native grass species due to its ability to efficiently recycle litter rich in
nutrients. Thus, nitrogen deposition may play a critical role in the future for the
persistence of this invasive species.
Predicting the role climate change may have on the potential distribution and
abundance of invasive species is an important consideration. A newly introduced
species that prospers under new climatic conditions may add additional hardships
to native species trying to adapt and survive under the new climate regime. These
types of models are difficult to produce because of the lack of accepted models for
future climate. Creating models to predict future climate and for invasive species
spread through time share problems, such as the inability to validate models - at
least until time has passed and changes have occurred. Using a variety of climate
change scenarios, models for the potential distribution of an invader could be cre-
ated for current climate and for climate conditions at certain times in the future, like
in 10 years, 20 years, 50 years, etc. Adding spread rates would only improve these
models. Comparison of the times series could illustrate populations of the invader
that are decreasing due to projected unsuitable climate in the future, stable popula-
tions due to projected suitable climate conditions currently and in the future, and
increasing populations due to increased climatic suitability as climate changes. This
