Saturday, January 12, 2008

Invasive Species & Climate Change

Invasive species and climate change are intertwined and interrelated. Discussing invasive plants without a grounding in climate metrics including CO2 levels will generate more hot air and fewer answers. It is interesting to me that invasive species awareness seems to have risen with CO2 levels. That CO2 would impact plant processes and growth is no surprise. I paraphrase Dr. Lewis Ziska, USDA BARS BARC, noting that one expects a change when one adds or subtracts water or nitrogen for example, so why should we not look for changes when we add or subtract carbon.

Some plants will process CO2 more efficiently than others; they will have a compentitive advantage which mat result in invasive response. Since Invasiveness is in some sense an ability to out compete, some species which can take advantage of the extra carbon will be in a position to out-compete other species. This phenomenon may perhaps explain why some plants, while introduced a century ago, are only now becoming a problem. Naturally, human disturbance and habitat alteration and or destruction play a role in the increased proliferation of invasive species.

C3, C4 and CAM photosynthetic pathways are also a consideration in the analysis of invasiveness and the upsurge we now are experiencing. Species with an inherent ability to process more carbon will perhaps have an innate ability to successfully compete with those plants which cannot use more carbon. As a tangential observation plant species which do not have supporting infrastructure such as branches and trunks, and which process carbon more efficiently, may divert their energy systems into growth. Vines such as kudzu provide and example of this potential, and explain somewhat the proclivity of vines to be problematic.

As we consider the impact of increasing carbon in the atmosphere on invasive plants, we also find that changes in basic climate such as temperature and precipitation produce stress in ecosystems which allow certain species to compete more efficiently. This brings into play the questions of native. If the climate changes, then we have a challenge with our simplified definition of native that is based on geography and a short time horizons. As invasive species solutions are offered which encourage the use of native only, we will necessarily quickly have to look for carbon increase effects as well as general climate modifications.

Moreover, invasive species issues constitute a core concern of eco-services which are found in a fully functioning self-sustaining eco-system. The complexity of the issues results in the wicked problem, or the wicked inconvenience (Invasive Species Conundrum: A Wicked Inconvenience) of which I have written previously. As we look for easy answers to complex problems, we provide avenues of unintended consequences. In a world which wants easy to digest, sound byte answers to everything, invasive species issues defy the desire. Banning plants without scientific inquiry and without thinking through the implication of climate change effect on the species behavior creates a set of alternative mitigation challenges complete with its own stakeholder groups’ attempts to simplify the resulting issues.

No comments: