Seed traits and germination of native grasses and invasive forbs are largely insensitive to parental temperature and CO₂concentration

Abstract

The structure and function of grassland ecosystems can be altered by a changing climate, including higher temperature and elevated atmospheric CO2 concentration. Previous studies suggest that there is no consistent trend in seed germination and seedling recruitment as affected by these conditions. We collected seeds of two native and two invasive species over 6 years from a field study with elevated CO2 (600 p.p.m.) and temperature (1.5/3.0°C day/night) on the mixed-grass prairie of Wyoming, USA. Seed fill, viability and mass were evaluated and germination tests were conducted under alternating temperatures in growth chambers. Thermal time requirements to reach 50% germination (θ50) and base temperatures (Tb) for germination were determined using thermal time models. Climate change conditions had limited effects on seed fill, viability and mass. The combination of CO2 enrichment and warming increased germination of Bouteloua gracilis. Centaurea diffusa and Linaria dalmatica, two invasive species in this study, had the lowest θ50 and Tb required for germination among all the species studied. Although final germination percentages of these invasive species were not affected by treatments, previous studies reported increased seed production under future climate conditions, indicating that they could be more invasive at the regeneration stage in the future. We conclude that projected future temperature increases will have little effect on seed reproductive traits of native species. In addition, the distribution and abundance of B. gracilis and invasive species may be favoured by global climate change due to enhanced germination or seed production traits caused by elevated parental CO2 and temperature conditions.

Climate Warming Facilitates Seed Germination in Native but Not Invasive Solidago canadensis Populations

“…Since climate warming can influence plant invasions (Bradley et al, 2010), this has particular relevance to seed quality and seed germination (Aragn-Gastlum et al, 2018). For example, recent studies have shown that climate warming may strongly influence seed quality and seed germination (Aragn-Gastlum et al, 2018;Li et al, 2018) and plant mortality and phenology during the invasion process (Peng et al, 2018;He and He, 2020). Plant populations from native and non-native ranges perform differentially, including reproductive output, seedling recruitment, individual density, and competitive ability (Lockwood et al, 2013).…”

High Temperature and Elevated CO2 Modify Phenology and Growth in Pepper Plants

“…Nevertheless, when the first Therefore, the interaction between temperature and CO 2 did not have a significant effect on the final emergence of either species of Capsicum evaluated. In contrast, a significant increase in the percentage of emergence was observed in Bouteloua gracilis with the combination of seven temperatures with alternating 12/12 h periods (10/0, 12.5/2.5, 15/5, 20/10, 25/15, 30/20, 35/25 • C) and CO 2 (385 and 600 µmol CO 2 mol −1 ) [18]. Moreover, [25] mention that CO 2 concentration did not have a significant effect on Arabidopsis thaliana seed emergence, with seeds subjected to high temperatures exhibiting the fastest germination rate.…”

“…The physiological response of seeds to this factor is crucial for emergence and plant development, and once the optimum temperature point is reached, the emergence process diminishes. Therefore, temperatures under or over the maximum optimum can inhibit emergence, risking the life and survival of seedlings [18,27,28].…”

“…There has been a clear increase in C a , with levels of the gas currently fluctuating around 416 µmol mol −1 [13], and this trend will continue for many years [14]. Nevertheless, it has been demonstrated that CO 2 has a beneficial effect on plants, especially in CO 2 -enriched environments, by improving photosynthetic efficiency, reducing transpiration losses, stimulating general growth [15], and turning on adaptive mechanisms in plants such as biomass generation and physiological and morphological changes, thus strengthening plants' thermotolerance to achieve better adaptation to climate conditions [16][17][18][19].…”