Changes in multiple environmental factors additively enhance the dominance of an exotic plant with a novel trade‐off pattern

Abstract

Whether global changes impact native and exotic species differently is unclear, because the changes may favour both native and exotic species over competitors. Previous studies have mainly focused on the separate effects of different environmental changes, but plant communities are influenced by the changes in multiple environmental factors, and it is still unclear whether native and exotic species respond similar to the combined effects of these factors. We hypothesized that differences in interspecific trade‐offs between native and exotic species can lead to the dominance of exotic species when the species are simultaneously subjected to multiple environmental changes. Using coastal saltmarsh plant communities as the study system, we experimentally manipulated flooding and nutrient enrichment, examined the interspecific trade‐offs between competitiveness and stress tolerance for two native and one exotic species, and explored the combined effect of the two environmental changes on both native–native and native–exotic species interactions. We found that flooding and nutrient enrichment oppositely affected native–native species interactions but additively affected native–exotic species interactions. The two factors together resulted in no net change in the relative advantages between the two native species but enhanced the dominance of the exotic species over the native species. This disparity occurred because the exotic species was not subject to the interspecific trade‐off between competitiveness and stress tolerance that constrained the native species. Synthesis. Our results suggest that changes in multiple environmental factors favour exotic species because of evolutionary novel trade‐off patterns. Mechanisms underlying species coexistence in the invaded community such as interspecific trade‐offs need to be considered when future attempts are made to predict the effects of global changes on biological invasions.

Effects of Region and Elevation on Adaptation of Leaf Functional Traits of an Invasive Plant Erigeron annuus in China

“…Exotic plant populations can use traits dominance to adapt to changed environments and defeat competitors in the new conditions of exotic communities [10][11][12]. The key for exotic species to settle is decided by synthesis of abiotic conditions and traits adaptation [13][14][15].…”

Effects of the Water-Sediment Regulation Scheme on the Expansion of Spartina alterniflora at the Yellow River Estuary, China

“…Spartina alterniflora (S. alterniflora), an exotic species native to the East Coast of North America, was introduced to coastal areas of China in 1979 for promoting sediment deposition and erosion control (Li et al, 2009). Ever since then, S. alterniflora has gradually expanded to large areas of estuarine and coastal wetlands due to its high salt tolerance and strong reproductive capacity (Liu et al, 2018;Qiu et al, 2020), and posed serious threats to local native ecosystems (Schwarz et al, 2016). The growth and expansion of S. alterniflora are dependent on a number of key physical factors in estuarine saltmarshes, such as surface elevation (Carey et al, 2017), inundation and salinity (Elsey-Quirk et al, 2009).…”

An invasive species erodes the performance of coastal wetland protected areas

“…In our case with the smooth cordgrass, a notorious coastal plant invader, although cordgrass planting by humans had either a shorter history in PAs (JDS, CM, and YC) compared to non-PAs or was absent (YRE) (see table S1), our results reveal that cordgrass invasions were more extensive in PAs and produced particularly destructive impacts on PAs. Although direct competitive replacements have been often emphasized in studies at small spatiotemporal scales (26)(27)(28), our study shows that the impacts of exotic cordgrass invasion on PAs can be more profound and far reaching because of multiple direct and indirect mechanisms operating at large spatiotemporal scales. Besides competitive replacement of native marshes, cordgrass invasions also (i) preemptively and irreversibly replaced expansive mudflats at lower elevations and (ii), through priority effects, precluded the successional formation of new native marshes in PAs with rapidly accreting mudflats.…”