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Contributed Talk

Session: : Invasion 2

COS 176-6 - Non-native species shift functional community composition across diverse ecoregions

Wednesday, August 9, 2023
11:15 AM – 11:30 AM PDT
Location: D137
Abstract: The establishment, spread, and proliferation of non-native plant species alters community composition and associated ecosystem functions and processes. Non-native species tend to have traits associated with the “fast” end of the leaf economic spectrum (LES) (e.g., high specific leaf area (SLA), high leaf nitrogen), are taller, and have root traits associated with independent (i.e., high specific root length (SRL)) and fast (i.e., low root tissue density (RTD)) belowground capture of resources. Given these differences, increased abundance of non-natives likely results in functional shifts of plant communities towards traits of non-native species. To date, investigations of community-level functional changes have been conducted at individual sites. Because of this, understanding of how non-native species shift functional attributes of communities across diverse ecosystems remains limited. By integrating data gathered from over 80,000 vegetation plots from the SPCIS dataset across the lower 48 United States with publicly available trait data from several trait databases, we determined how non-native species shift functional attributes of communities across several ecoregions including deserts, grasslands, and forests. We assessed how non-native species shift community weighted means (CWM) of LES traits as well as traits related to understudied axes of aboveground and belowground functional variation, including height, maximum rooting depth, and the root economic space.

Consistent with expectations, we found highly invaded communities had higher CWMs for leaf nitrogen, SLA, and SRL, and lower RTD and leaf dry matter content. However, contrary to expectations, we found highly invaded communities had low CWM plant height and maximum rooting depth. While these shifts are predominantly consistent across ecoregions, some exceptions occur. For example, patterns in LES traits related to non-native species abundance vary much less in forested regions than in regions dominated by herbaceous vegetation such as deserts and plains. Our results demonstrate that non-native species consistently shift functional attributes of plant communities across diverse ecoregions and large scales. Given established links between traits and ecosystem functions, these findings provide new insight into how non-native plants are altering ecosystem dynamics in a rapidly changing world.