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In nature, the synchronization of life events—like the blooming of flowers in spring, the mating of cicadas during summer, and the emergence of caterpillars—carries immense importance and has even inspired a dedicated field of study known as phenology.
This discipline primarily examines seasonal patterns; however, in light of a changing climate, researchers are uncovering various disruptions that affect the timing and interactions among different organisms within the ecosystem.
A recent study featured in Nature Climate Change, conducted by a research team led by Daijiang Li, an ecologist at the University of Arizona, investigates how extreme weather phenomena influence the phenology of butterflies, moths, and flowering plants throughout the United States.
Despite their significant impacts on biological ecosystems, severe weather events such as heat waves, cold snaps, excessive rainfall, and droughts are often neglected in research. Many studies tend to focus on gradual climate shifts instead of these abrupt events, creating a critical void in knowledge concerning their effects on ecosystems amid ongoing climate change.
“Typically, research has concentrated on average climatic variables or seasonal trends, like yearly temperature or precipitation averages,” explained Li, an assistant professor in the Department of Ecology and Evolutionary Biology at U of A. “However, individuals react to immediate environmental challenges instead of long-term trends, right?”
Li and his collaborators assert that incorporating the study of extreme weather events is essential for enhancing predictions about how plant and animal phenology adapts to global changes. Their findings indicate that while average temperatures significantly influence phenological processes, the repercussions of extreme weather should be regarded as equally significant.
“Our data present compelling evidence showing that extreme weather events and the climatic conditions in which they arise are key to understanding how plants and insects respond phenologically,” Li remarked.
The study also revealed that extreme weather not only has direct effects on plants and insects, but also interacts with varying climatic factors, according to Li.
“For instance, surprisingly hot and dry spells can lead to compounded effects on phenology,” he noted. “These elements do not function independently but rather work in concert with each other and climatic changes to influence the phenological patterns of plants and insects collectively.”
The researchers utilized data compiled by citizen scientists through iNaturalist, a popular app that enables users to identify, document, and contribute observations of flora and fauna to a global database. This citizen-reported information was then combined with daily weather records spanning from 1980 to 2022.
“We analyzed around 581 species of angiosperms (flowering plants) and 172 species of Lepidoptera (butterflies and moths) from 2016 to 2022,” said Li. “Our research also explored the spatial distribution of the species and the respective impacts of extreme weather on their phenological patterns, along with examining whether they respond similarly or differently to such events.”
One particular concern highlighted in the research is the disruption of crucial interspecies relationships, as seen in the interaction between the yucca plant and the yucca moth. The yucca moth relies on the yucca plant for sustenance and, in exchange, pollinates its flowers.
“If insect larvae respond too sensitively to early spring heat waves, they may face increased mortality once temperatures stabilize or during sudden cold snaps,” Li mentioned. “Likewise, if spring temperatures are unusually warm, it can lead to earlier flowering in plants, thereby exposing them to risks like late frosts during the growing season.”
The finely balanced interdependencies among species are at risk of disruption from both long-term climate trends and short-term extreme weather occurrences. If the emergence periods of pollinators like butterflies and moths do not align with plant flowering, it could result in pollinators struggling to find food and flowers failing to receive necessary pollination.
While the study observed that plants and insects often exhibit comparable phenological responses to extreme weather, there can also be significant discrepancies. For instance, cold snaps during spring prompted adult butterflies and moths to emerge earlier than usual, whereas plant flowering remained largely unaffected during these conditions.
“Such phenological mismatches can have serious repercussions for both plants and insects, leading to declines in their populations,” Li cautioned.
Li, along with co-authors Michael Belitz, Lindsay Campbell, and Robert Guralnick from the University of Florida, aims to incorporate extreme weather considerations into climate models. Their hope is that a more nuanced understanding will lead to better predictions regarding ecological mismatches and aid in developing effective strategies for mitigation and resilience in light of climate change.
“This research holds potential significance across various sectors, from conservation efforts to food security,” commented Campbell, an assistant professor at the Florida Medical Entomology Laboratory.
“Our understanding of how extreme weather impacts insects and plants—and, by extension, human food security—is still in its infancy,” noted Guralnick, curator of biodiversity informatics at the Florida Museum of Natural History. “This study marks a meaningful advancement towards that understanding.”
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