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Wildflower and pollinator communities are silently shifting

According to the Intergovernmental Panel on Climate Change’s (IPCC) intermediate emissions scenario RCP4.5, it is predicted that global average temperatures will rise by between 0.9 and 2.0  degrees Celsius until mid-21st century. As a result, many species, particularly specialists with very specific food, habitat, and reproductive requirements, may not be able to adapt to these changes.

A research team led by Newcastle University has recently investigated the impact of global warming on the fitness of insects and the wildflowers on which they depend for food, by simulating climate change on outdoor experimental plots at an agricultural research station in the UK.

According to study lead author Dr. Ellen Moss, a postdoctoral researcher in Entomology and Ecology at Newcastle University, a 1.5°C increase in temperature can drastically reduce food resources for pollinating insects, cause pollinators to visit a wider range of plants for food, and reduce seed production for some wildflowers, while increasing it for others.

Dr. Moss and her colleagues raised the ambient temperature of the experimental plots by a constant 1.5ºC with infrared heaters, and compared plant and insect biodiversity, as well as insects’ visiting patterns on the flowers, between these plots and unheated control plots during 2014 and 2015. Since climate change in northern Europe is predicted to lead to an increase in rainfall too, the scientists irrigated some of the experimental plots with extra water, both in combination with and separately from heating.

They found that the number of plant or insect species did not change significantly in the experimental plots, suggesting that heating by 1.5 ºC, with or without extra water, does not lead to immediate changes in species diversity. Instead, the immediate effects were more subtle. For instance, most of the plant species from the heated plots were “losers” in reproductive terms: they grew fewer flowers and produced fewer or lighter seeds.

“Our experiment showed that under an increase of 1.5°C there was almost a 40 percent reduction in the number of floral units throughout the season, which represents a significant decrease in available food for flower visitors,” the study authors reported.

Moreover, this reduction in available food caused subtle changes in insect foraging behavior too, with insect species tending to visit a greater number of plant species, and to return to each flower more times. 

“Our results demonstrate that climate warming could have severe consequences for some species of wildflowers and their pollinators in agricultural systems, and shows that their community composition is likely to change in the future,” Dr. Moss concluded.

The study is published in the journal Frontiers in Plant Science.

By Andrei Ionescu, Staff Writer

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