Salt‐tolerant native plants have greater responses to other environments when compared to salt‐tolerant invasive plants

Abstract

The strong expansion potential of invasive plants is often attributed to fast adaptive responses to stress. However, the evolution of tolerance to one stressor may affect the responses to other stressors. Currently, it remains unclear what effect the evolution to one stressor might have on the responses to other single or combined stressors. Moreover, it is unknown how this might differ between invasive and native species. Invasive plants ( Mikania micrantha and Bidens pilosa ) and native plants ( Merremia hederacea and Sida acuta ) from low‐ and high‐salinity habitats were grown under control and stressful conditions [salt stress, water stress (drought/waterlogging), and their combinations]. We explored the effects of evolved salt tolerance on the responses to water stress/combined stresses and the underlying trait mechanisms. The high‐salinity populations of all species exhibited stronger salt tolerance than the low‐salinity populations. As to the tolerance to other stressors, the high‐salinity and low‐salinity populations of the invasive species were similar, whereas the high‐salinity populations of the native species exhibited stronger tolerance than the low‐salinity populations under most stress treatments. However, the enhanced salt tolerance in native species was accompanied by reduced total biomass under control condition. The stress tolerance of native species correlated with leaf production rate and allocation to root, while the performance of native species under control condition correlated with leaf morphology and carbon assimilation rate. This suggests a trade‐off between salt tolerance and performance in the native but not the invasive species, probably resulting from altered phenotypic/physiological traits. Synthesis Our work suggests that the evolution of tolerance to one stressor may have stronger effects on the tolerance to other stressors of the native compared with the invasive species. This may be a new paradigm to explain the greater advantage of invasive vs. native species in highly stressful habitats.

Adaptive responses to living in stressful habitats: Do invasive and native plant populations use different strategies?

“…Previous research suggests that invasive populations may have: (1) lower stress tolerance than native populations (e.g., Dlugosch et al., 2015), (2) less optimal stress responses than native species (O'Connell & Savage, 2020), or (3) lower performance than native species under more extreme stress (Schumacher et al., 2008). Our findings together with earlier studies (e.g., Liu et al., 2019; Welles & Funk, 2021) indicate that relatively few highly successful invasive species have high baseline tolerance that makes adaptation less necessary when settling into stressful sites. For example, some invasive species do not show adaptation, but plasticity across various stressful sites, such as sweet vernal grass ( Anthoxanthum odoratum L., Platenkamp, 1990) in sites characterized by salinity, serpentine soils, and dryness (Table S1).…”

“…A previous study found that invasive species in their native ranges produced more biomass under heavy shading compared to non-invasive species (van Kleunen et al, 2011). Liu et al (2019) compared high and low salinity ecotypes of invasive and native species and found that the natives had greater costs of salt tolerance. Moreover, the invasive species had higher overall tolerance to other stressors, but lowsalinity ecotypes of native species had the lowest tolerance (Liu et al, 2019).…”

Functional Traits Plasticity of the Invasive Herb Argemone ochroleuca Sweet in Different Arid Habitats

“…Although the root allocation is affected more strongly by variation in soil nutrients [ 73 ], the A. ochroleuca showed more allocation to root in the abandoned fields habitat which attained the highest content of nitrogen. Therefore, this suggests that A. ochroleuca in abandoned fields was responding to combined stressful conditions; possibly salinity and anthropogenic stresses rather than to a resource limitation [ 74 ].…”

Effects of salt stress on interspecific competition between an invasive alien plant Oenothera biennis and three native species

“…Extensive studies have been conducted on the effects of salt stress on the morphology and physiology of invasive and native individually ( Mao et al., 2016 ; Baniasadi et al., 2018 ; Liu et al., 2019 ). However, little research has focused on whether the competitive effects between invasive and native species are affected by salinity.…”

“…Further, salinity could influence invasion success, i.e., high salinity might increase the relative competitive ability of either native or invasive species depending on their tolerance ( Al Hassan et al., 2016 ). Previous studies have demonstrated that salinity can enhance the replacement of native plants by invasive plants ( Liu et al., 2015 ; Bollen et al., 2016 ; Legault et al., 2018 ), but salinity also can inhibit the establishment and performance of some invasive plants ( Qi et al., 2017 ; Liu et al., 2019 ). Therefore, whether salinity can promote the invasion of exotic species is debatable.…”