Exotic Invasive Plant Species Increase Primary Productivity, but Not in Their Native Ranges.

Area of Science:

• Ecology
• Invasive Species Biology
• Plant Ecology

Background:

• Ecosystem net primary productivity (NPP) is often limited by abiotic factors.
• Exotic invasive plants are frequently associated with increased ecosystem productivity.
• Previous studies lacked experimental evidence to distinguish invasion effects from species-specific traits or site selection.

Purpose of the Study:

• To determine if exotic invasive plants actively drive increased ecosystem productivity or if they are merely passengers in more productive environments.
• To differentiate the impact of invasion per se from inherent species productivity or microsite colonization advantages.

Main Methods:

• Aboveground biomass was measured for five plant species in both their native and non-native ranges.
• Field studies and common garden experiments were conducted to control for environmental variables.
• Comparative analysis of biomass in native vs. non-native ranges was performed.

Main Results:

• Exotic invaders increased total plot productivity by 91% in field studies and 107% in common gardens within their non-native ranges.
• These productivity-enhancing effects were significantly smaller or absent in the native ranges of the studied species.
• The observed increase in productivity was consistent across species when introduced to new environments.

Conclusions:

• Exotic invasive plants act as a significant driver of increased ecosystem productivity, particularly in their non-native ranges.
• The enhanced productivity is an effect of the invasion process itself, not solely due to the inherent traits of the species or their colonization of already productive sites.
• Understanding the mechanisms behind this invasion-driven productivity is crucial for predicting ecosystem responses to biological invasions.