The roles of species' relatedness and climate of origin in determining optical leaf traits over a large set of taxa growing at high elevation and high latitude

Effects of UV-B radiation on pollen germination and tube growth: A global meta-analysis

Despite widespread recognition of pollen's potential sensitivity to ultraviolet-B (UV-B) radiation (280-315 nm), there remains ongoing debate surrounding the extent and mechanisms of this effect. In this study, using published data on pollen germination and tube growth including 377 pair-wise comparisons from 77 species in 30 families, we present the first global quantification of the effects of UV-B radiation on pollen germination and tube growth, along with its underlying mechanisms. Our results showed a substantial reduction in both pollen germination and tube growth in response to UV-B radiation, affecting 90.9 % and 84.2 % of species, respectively. Notably, these reductions exhibited phylogenetic constraints, highlighting the role of evolutionary history in shaping the sensitivity of pollen germination and tube growth to UV-B radiation. A negative correlation between elevation and the sensitivity of pollen tube growth was detected, suggesting that pollens from plants at higher elevations exhibit greater resistance to UV-B radiation. Our investigation also revealed that the effects of UV-B radiation on pollen germination and tube growth were influenced by a range of abiotic and biotic factors. Nevertheless, the intensity and duration of UV-B radiation exposure exhibited the highest explanatory power for the effects on both pollen germination and tube growth. This suggests that the responses of pollens to UV-B radiation are profoundly influenced by its dose, a critical consideration within the context of global change. In conclusion, our study provides valuable insights into the diverse responses of pollen germination and tube growth to UV-B radiation, highlighting the environment and species-dependent nature of pollen's susceptibility to UV-B radiation, with substantial implications for our understanding of the ecological and agricultural consequences of ongoing changes in UV-B radiation.

Interactive effects of changes in UV radiation and climate on terrestrial ecosystems, biogeochemical cycles, and feedbacks to the climate system

Terrestrial organisms and ecosystems are being exposed to new and rapidly changing combinations of solar UV radiation and other environmental factors because of ongoing changes in stratospheric ozone and climate. In this Quadrennial Assessment, we examine the interactive effects of changes in stratospheric ozone, UV radiation and climate on terrestrial ecosystems and biogeochemical cycles in the context of the Montreal Protocol. We specifically assess effects on terrestrial organisms, agriculture and food supply, biodiversity, ecosystem services and feedbacks to the climate system. Emphasis is placed on the role of extreme climate events in altering the exposure to UV radiation of organisms and ecosystems and the potential effects on biodiversity. We also address the responses of plants to increased temporal variability in solar UV radiation, the interactive effects of UV radiation and other climate change factors (e.g. drought, temperature) on crops, and the role of UV radiation in driving the breakdown of organic matter from dead plant material (i.e. litter) and biocides (pesticides and herbicides). Our assessment indicates that UV radiation and climate interact in various ways to affect the structure and function of terrestrial ecosystems, and that by protecting the ozone layer, the Montreal Protocol continues to play a vital role in maintaining healthy, diverse ecosystems on land that sustain life on Earth. Furthermore, the Montreal Protocol and its Kigali Amendment are mitigating some of the negative environmental consequences of climate change by limiting the emissions of greenhouse gases and protecting the carbon sequestration potential of vegetation and the terrestrial carbon pool.