Impacts of climate change (increased temperature, altered precipitation regimes) on invasion

Invasion, an important global change in its own right, will most certainly interact with other aspects of human-caused global change, such as climate change. For many regions, climate is predicted to be impacted by human activities in two ways: through altered timing in precipitation and increased temperature. These changes may facilitate invasion by exotic plants by altering resource supply and demand. Thus, current understanding of invasion will likely be further complicated by predicted climate changes.

Community theory predicts that invasion should occur only when there is a niche opportunity. These can result from an enemy escape or resource opportunity. Resource opportunities arise in two ways: 1) directly due to an increase in resource supply beyond that required by resident species, or 2) indirectly due to a decline in resource use by resident species. An increase in resource supply or decrease in demand may result from a variety of mechanisms, including fluctuation in climate, disturbance or resource enrichment. Changes in the mean and variability in climate may lead to pulses in water and N availability that could alter resources opportunities for invaders at different times of during the growing season and different stages of the invasion process.

As part of a larger, long-term experiment (supported by funding from the USDA and NSF) in intact, tallgrass prairie (the Rainfall Manipulation Plots (RaMPs)) examining community and ecosystem responses to experimental warming (+1-2°C) and more extreme precipitation patterns (30% increase in timing between rainfall events, but no change in total precipitation), we are examining the effects of these climate changes on invasion by several exotic plant species over time. With this long-term invasion experiment, we hope to gain a more detailed mechanistic understanding of invasion and how climatic changes may impact invasibility of ecosystems. We are expanding these studies to a broader precipitation using three sites within the Nutrient Network, as well as incorporating other trophic levels, to examine the impacts of multiple resource limitation and trophic interactions on invasion by woody plant species.

Other Current Initiatives

• 1) An integrative gene-to-ecosystem understanding of the ecological consequences of climate change



• 2) Implications of altered disturbance regimes for grasslands: a comparative approach



• 4) The role of dominant plant species in the structure and function of ecosystems



• 5) The Climate Extremes Experiment (CEE): Examining threshold responses of the tallgrass prairie ecosystem to temperature and precipitation extremes.



• 6) Global warming impacts on CT salt marsh ecosystems and consequent effects on salt marsh vulnerability to sea level rise