Invasibility, Invasives, and Novel Ecosystems – overview

PUBLICATIONS

Water hyacinth was once considered to be the aquatic scourge of the southeastern U.S. Forty years ago its distribution was thought to be limited only by dispersal: “Clean Propeller Before Launch” the signs commanded. I wasn’t so sure, and in the early 1970s the first graduate student to work with me, Tom Morris (now a world renowned karst geohydrologist) did a master’s thesis that put this idea to the test. We selected a number of aquatic habitats, ranging from nutrient rich to nutrient poor, and we introduced small clumps of water hyacinth into circular enclosures a couple of meters in diameter. In the most heavily polluted waters (nutrient-rich treated sewage effluent) the hyacinths were soon dark green and nearly a meter tall, and the enclosures were bursting at the seams; in the most nutrient poor waters (clear-water ponds in infertile sandhills) the hyacinths were pallid and stunted. The weed wasn’t the issue; the environmental change brought on by human activities was the villain.

This thread continued in a number of studies, including extensive work by colleague and former student Ron Myers who did analogous studies with an invasive tree in South Florida, Melaleuca quinquenervia. (See Myers’ paper in the Journal of Applied Ecology, 1983, and a number of subsequent articles, including several that link Melaleuca and fire.)

By this time militaristic attitudes against non-native species were becoming increasingly entrenched in the ecological and conservation literature. Meanwhile, my colleagues and I continued to look at invasive species from the perspective of the invaded rather than the invader. But scientists need to continue to look at both sides of the issue – invader and ecosystem invasibility – and today increasingly sophisticated tools are being brought to bear on the task.

It is not a long step from community invasibility to the recognition that most of today’s landscape reflects irrevocable changes due to land use and human-mediated transport of species around the globe. What will tomorrow’s ecosystems look like, and how with they function? Understanding the structure and function of novel ecosystems broadly defines my main current interest. We need not only to accept ecological novelty where it is inevitable, but we also need to learn how to best manage new ecosystems so that they best conserve the unique products of evolution and provide the ecosystem services on which we depend.