Scientists are still trying to understand what drives the relentless spread of invasive species in the United States.
Invasions are often assessed by measuring species richness, or the number of non-native species known to grow in a certain area. However, other measurements of plant invasions could offer more insights.
“We can make stronger inferences about invasions when we account for multiple invasion measures, as well as the diversity of ecosystems across large geographic areas,” says U.S. Forest Service Southern Research Station (SRS) scientist Christopher Oswalt.
Oswalt, research forester at the SRS Forest Inventory and Analysis (FIA) unit, co-authored a recent study that evaluates the patterns and drivers of forest plant invasions over large scales. The study was led by Basil Iannone, a postdoctoral research associate at Purdue University, and published in the journal Diversity and Distributions. Multiple scientists from Purdue University, as well as the Forest Service Southern and Northern Research Stations collaborated on the study.
The scientists used data from FIA to compile and map the number of invasive species, as well as the percentage of plots invaded, and compared forest plant invasions in two ecologically distinct regions of the U.S. – eastern and western forests. Data from 2,524 counties were analyzed.