Increased soil moisture aggravated the competitive effects of the invasive tree Rhus typhina on the native tree Cotinus coggygria

Abstract

Background: Invasive exotic species have caused significant problems, and the effects of extreme precipitation and drought, which might occur more frequently under the global climate change scenarios, on interspecific relationship between invasive and native species remain unclear. Results: We conducted a greenhouse experiment with three soil water levels (30-40%, 50-60%, and 70-80% of field capacity) and two cultivation treatments (monoculture pots, one seedling of either species and mixture pots, one seedling of each species) to investigate soil water content effects on the relationship between invasive Rhus typhina and native Cotinus coggygria. Rhus typhina had lower height but bigger crown area than C. coggygria in the monoculture treatment. Rhus typhina had higher height, bigger crown area and total biomass than C. coggygria in the mixture treatment. Drought decreased the growth parameters, total chlorophyll concentration, and leaf biomass, but did not change gas exchange and other biomass parameters in R. typhina. The growth parameters, leaf area index, biomass parameters, total chlorophyll concentration, and net photosynthetic rate of C. coggygria decreased under drought conditions. The log response ratio (lnRR), calculated as ln (total biomass of a target plant grown in monoculture/total biomass of a target plant grown in mixed culture), of R. typhina was lower than that of C. coggygria. The lnRR of R. typhina and C. coggygria decreased and increased with increase in soil water content, respectively. Conclusions: Rhus typhina has greater capacity to relatively stable growth to the drought condition than C. coggygria and has strong competition advantages in the mixture with C. coggygria, especially in the drought condition. Our study will help understand the causes of invasiveness and wide distribution of R. typhina under various moisture conditions and predict its expansion under climate change scenarios.

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

“…Plant functional traits play a key role in the competition between invasive and native species, including growth rate, biomass allocation, SLA, and photosynthetic traits ( Wang et al., 2018 ; Rathee et al., 2021 ). In our study, most functional traits of O. biennis were significantly different from C. album and I. japonica suggesting that our results support the phenotypic divergence hypothesis rather than the phenotypic convergence hypothesis ( Ordonez et al., 2010 ; Guo et al., 2020 ), meaning that O. biennis has significantly advantageous traits compared to the native C. album and I. japonica . According to the results of PCA, invasive species O. biennis and two native species C. album and I. japonica were clearly separated, and besides, the differences in most trait values were different, which also supported the phenotypic divergence hypothesis ( Ordonez et al., 2010 ).…”

“…When mixed with I. japonica , O. biennis had higher LBR, H, CA, SLA, Fv/Fm, and Chl and lower RSR, indicating that O. biennis obtained more light energy and accumulated more biomass through aboveground traits, and outcompeted I. japonica . Invasive plants often adopt different biomass allocation strategies in response to environmental changes to create a competitive advantage for themselves ( Guo et al., 2020 ). Allocating more biomass from roots to aboveground parts, O. biennis obtained a higher height and a large canopy than I. japonica , which contributed to capturing light effectively and inhibited the growth of I. japonica through shading ( Luo et al., 2014 ).…”

“…The phenotypic convergence hypothesis is based on habitat filtering mechanisms and states that alien species that are more similar to native communities are more likely to succeed ( Ordonez et al., 2010 ; Drenovsky et al., 2012 ). The phenotypic divergence hypothesis is based on limiting similarity and suggests instead that the differences in functional traits between invasive and native species contribute to the success of invasive species ( MacArthur and Levins, 1967 ; Ordonez et al., 2010 ; Guo et al., 2020 ). An earlier meta-analysis suggested that invasive alien plant species generally have higher values than some native plants for traits reflecting physiology, size, and fitness ( van Kleunen et al., 2010 ).…”

Grass fires and road structure influence plant invasions in a critical wildlife habitat in north-eastern India

“…It is also expected that the greater niche complementarity of species-rich plant communities would provide fewer opportunities for invading species to exploit, so the higher native plant density of intact vegetation should be associated with lower invasive species abundance. At smaller spatial scales, soil water availability is often affected by numerous environmental factors, such as soil type, landscape position and topography (Jacobs 2004), and water availability will affect the relative performance of invasive and native plant species (Guo et al 2020). In Terai habitats such as those in MNP, seasonal floods may inundate some sites for several weeks or even months.…”

“…To capture the habitat and topographical effects on water availability and the potential influence of seasonal inundation, we quantified the spatial patterns of flooding, elevation, slope and a satellite-derived drought stress index (Wang & Qu 2007) as explanatory variables. Increased soil moisture conditions aggravate the competitive effects of invasive plants (Guo et al 2020), so we predicted that the variables associated with soil moisture would be strongly correlated with invasive species abundance.…”