The right place in the night time - Nighttime warming affects relative growth of native versus invasive plants
Written and edited by Suvi Birch, Abigail Guinan, Justin Salva, Nikki Read
Summary
Generally, increasing temperatures have been shown to increase the performance of invasive plants relative to native plants (see Liu et al. 2017). However, climate change could alter the timing of increasing temperatures - for example, in the Northeast, winter temperatures are warming faster than summer temperatures. Similarly, nighttime temperatures could warm at a different rate to daytime temperatures. In both cases, this differential warming could affect the relative performance and competition between invasive and native plants. This study looked at how day and night warming affect native and invasive plant growth, both individually and grown in competition. The study focused on subtropical species, with three native to Guangzhou, China (Vernonia cinerea, Emilia sonchifolia and Spilanthes paniculata) and three invasive in China and native to Central and South America (Bidens pilosa var. radiata, Ageratum conyzoides and Eupatorium catarium). Six monocultures and nine mixed cultures underwent control, day warming, night warming, and whole day warming trials in growth chambers. In this study, nighttime warming led to significantly higher root biomass in native plants, but not invasive plants. Nighttime warming led to lower specific leaf area (SLA) in native plants, which likely reduced stomatal opening during the day and increased photosynthetic rates. However, when the plants were grown in competition, the benefit of nighttime warming to native plant root biomass was negated.
Take home points
Daytime and nighttime warming could lead to different responses in plant growth rates and leaf shape because photosynthesis happens during the day, while respiration happens during the day and night.
Management implications
While a general expectation is that invasive plants will perform better under warming, the effect of warming on plant growth can vary depending on the timing (day versus night) and seasonality (winter versus summer) of warming.
Differences in plant growth rates observed when plants are grown alone (in monoculture) can change when plants are grown in competition - thus, managers should be cautious about interpreting warming experiments that do not include competition.
Keywords
Asymmetric warming, Plant growth, Competition, Daytime warming, Nighttime warming