Long‐term effects of artificial nighttime lighting and trophic complexity on plant biomass and foliar carbon and nitrogen in a grassland community

Abstract

The introduction of artificial nighttime lighting due to human settlements and transport networks is increasingly altering the timing, intensity, and spectra of natural light regimes worldwide. Much of the research on the impacts of nighttime light pollution on organisms has focused on animal species. Little is known about the impacts of daylength extension due to outdoor lighting technologies on wild plant communities, despite the fact that plant growth and development are under photoperiodic control. In a five‐year field experiment, artificial ecosystems (“mesocosms”) of grassland communities both alone or in combination with invertebrate herbivores and predators were exposed to light treatments that simulated street lighting technologies (low‐pressure sodium, and light‐emitting diode [LED]‐based white lighting), at ground‐level illuminance. Most of the plant species in the mesocosms did not exhibit changes in biomass accumulation after 5 years of exposure to the light treatments. However, the white LED treatment had a significant negative effect on biomass production in the herbaceous species Lotus pedunculatus . Likewise, the interaction between the white LED treatment and the presence of herbivores significantly reduced the mean shoot/root ratio of the grass species Holcus lanatus . Artificial nighttime lighting had no effect on the foliar carbon or nitrogen in most of the grassland species. Nevertheless, the white LED treatment significantly increased the leaf nitrogen content in Lotus corniculatus in the presence of herbivores. Long‐term exposure to artificial light at night had no general effects on plant biomass responses in experimental grassland communities. However, species‐specific and negative effects of cool white LED lighting at ground‐level illuminance on biomass production and allocation in mixed plant communities are suggested by our findings. Further studies on the impacts of light pollution on biomass accumulation in plant communities are required as these effects could be mediated by different factors, including herbivory, competition, and soil nutrient availability.

How artificial light at night may rewire ecological networks: concepts and models

“…Studies have found that primary producers respond to ALAN with changes in traits, phenology, biomass and structure [31,[33][34][35][36]. These changes at the base of food webs can have severe impacts on species interactions and the functioning of whole communities.…”

Analyzing the Effects of Urban Photopollution on Photosynthetic Efficiency of Certain Trees through Chlorophyll Fluorescence OJIP Transient

“…Study of the physiological mechanisms by which plants adapt to artificial light at night will help to select the species suitable for urban plantations and, consequently, to determine the success of urban plantations. Indeed, few previous studies were conducted in the natural environment, and most of the earlier findings on artificial light at night (ALAN) were mainly focused on plant ecosystem sustainability, while the studies showing the effects of ALAN on plant physiological processes were reported in very small numbers [24][25][26][27]. Trees growing under street-light conditions experience an extremely heterogeneous environment; therefore, the use of traditional analytical approaches in the early detection of stress would be expensive and time-consuming [28].…”