The average global temperature is projected to rise by 0.9–2.0 ºC around the middle of this century, according to the IPCC RCP4.5 interim emission scenario. As a result, many species, especially specialists with very specific requirements for food, habitat and reproduction, will not be able to adapt.
Since approximately 35% of our crops depend on insects for pollination, it is necessary to study the effect of global warming on the suitability of the insects and wildflowers on which they depend. food. Once we understand the likely changes, we may be able to mitigate them negative consequences for wild and agricultural plants.
A study conducted by scientists from the University of Newcastle in the UK, is the first to experimentally show the immediate effects of simulated climate change on the reproductive success of wildflowers, as well as on the food web plants and pollinators. The results are published in Boundaries in plant science.
Lead author Dr. Ellen D. Moss, Ph.D., of the School of Natural and Environmental Sciences at the University of Newcastle, said: a wide range of plants to eat, and cut seed production for some wildflowers, while increasing it for others ”.
Simulation of global warming in the wild
The authors simulated global warming at open experimental sites at an agricultural research station in the UK, raising the ambient temperature to a constant 1.5 ºC using infrared heaters. They then compared plant and insect biodiversity, as well as samples of insect visits on flowers between these and unheated control sites in 2014 and 2015.
As climate change in northern Europe is also projected to increase rainfall, they have further looked at the effect of irrigating areas with additional water (supplying 40% of local monthly rainfall in addition to natural rainfall), both in combination with and apart from heating.
Between the years, the fields were plowed, and in the spring sown with wheat and eight species of local annual grasses pollinated by insects characteristic of wheat fields such as calendula and cornflower. No pesticides were used, which also allowed local wildflowers to colonize fields and flowers.
Throughout the flowering period, from June to August, the authors counted the number of plant species present at each plot and the number of flowers at each. They also weighed the dried ripe seeds for each species and measured the amount of nectar per flower. Finally, at regular intervals throughout the season, they counted the number of insects visiting each plant species over 20-minute periods, and collected these insects so that experts could identify the species.
In 2014, the authors observed 25 species of plants and 80 species of insects, and in 2015 – for 19 and 69 species of insects. without additional water, does not lead to immediate changes in species diversity. Most likely, the immediate effects were more subtle. For example, most plant species were “losers” in reproductive terms when heating plots: they grew fewer flowers or produced fewer or lighter seeds.
“Our experiment showed that when the temperature increased by 1.5 ° C, the number of flower units decreased by almost 40% throughout the season, which means a significant reduction in available food for flower visitors,” the authors write.
The only “winner”
The only “winner” in reproductive conditions in simulated climate change was a wild field field saddle, which gave more and heavier seeds in heated areas. However, its flowers emit 65% less nectar in heated areas, which makes this species less useful for pollinators.
Researchers also observed subtle, immediate changes in the food web. For example, in heated areas, the food web was more complex because insect species tended to visit more plant species, while the number of visits per flower was increased. This change in insect behavior in search of food was probably caused by a reduction in available food. And although the number of registered species was not affected by heating or additional water, the composition of both plants and insects differed significantly between treatments.
“Our results show that global warming could have serious consequences for some species of wildflowers and their pollinators in agricultural systems, and show that the composition of their community is likely to change in the future,” Moss said.
Co-author Dr Darren Evans, a professor of ecology and conservation at the University of Newcastle, said: “Our results provide valuable insight into how global warming affects not only uncultivated plants but also how species commonly considered weeds lie. at the heart of important insect pollinating communities ”.
“Looking ahead, it is better to understand how global warming affects the direct and indirect effects of a fuller network species interaction will enable us to better adapt our agricultural systems to a changing world. ”
Experimental global warming is reducing flower resources and changing visits to insects and wildflower seeds in the cereal agroecosystem, Boundaries in plant science (2022). DOI: 10.3389 / fpls.2022.826205 , www.frontiersin.org/articles/1… pls.2022.826205 / full
Citation: A sharp drop in the number of flowers caused by the climate crisis will force pollinators to continue looking for food (February 23, 2022, February 23, 2022), obtained from https://phys.org/news/2022-02-sharp-abundance-climate -crisis- pollinators.html
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