Nature’s timing is drastically changing due to extreme weather

The timing of biological events in nature is crucial for survival. Flowers bloom in spring, cicadas mate in summer, and caterpillars hatch to feed on their host plants.

However, extreme weather can disrupt this natural schedule – known as phenology – upsetting the delicate balance of ecosystems.

Climate change and nature’s timing

Phenology is closely tied to seasonal patterns, but climate change is interfering with nature’s timing and causing shifts in how organisms interact.

A study led by University of Arizona ecologist Daijiang Li has explored how extreme weather affects phenology. The team focused on butterflies, moths, and flowering plants across the United States.

Extreme weather events, such as heat waves, cold snaps, heavy rainfall, and droughts, impact ecosystems but are often overlooked. Most research examines gradual climate shifts rather than immediate weather extremes.

This oversight creates a knowledge gap in understanding how sudden changes affect species and their interactions.

Immediate impact of extreme weather

“Most studies have focused on climatic variables or seasonalities, such as annual temperatures or precipitation averages,” said Li.

“But as individuals, we respond to and make our decisions in response to immediate environmental stress, rather than a 10-year trend, right?”

Li and his team found that extreme weather events play a significant role in phenology, comparable to average temperature changes. The research showed that these events interact with climatic variables, influencing plants and insects in complex ways.

Compounding effects of weather extremes

“For example, extremely hot and extremely dry periods can have a compounding effect on the phenology,” Li said.

“These variables don’t occur in isolation. Rather, they interact with each other and interact with climatic variables in driving the phenology of plants and insects as a whole.”

The researchers analyzed data collected by citizen scientists through iNaturalist. This app allows users to document species by taking photos and uploading them to a database. Li’s team combined iNaturalist records with daily weather data from 1980 to 2022.

Species-specific responses

“We looked at about 581 species of angiosperms (flowering plants) and the flying adults of 172 Lepidoptera species (butterflies and moths) from 2016 to 2022,” Li said.

“We also looked at the spatial distribution patterns, how extreme weather events affect the phenology of those plants and insects, and also whether the plants and insects have similar or different responses to extreme weather events.”

One concern is how extreme weather disrupts relationships between species. Some species depend on precise timing for survival. The yucca plant and yucca moth, for example, rely on each other.

The moth pollinates the yucca flowers, while the plant provides food for its larvae. If this timing is disrupted, both species suffer.

Risk of phenological mismatches

“If larval stages of insects are too responsive to early spring heat waves, they may be more susceptible to mortality when temperatures return to normal or during cold snaps,” Li said.

“Similarly, if spring is warmer than usual, plants are going to flower earlier, making them more vulnerable to late frost during growing season.”

If pollinators like butterflies or moths emerge before or after plants flower, both struggle. Pollinators cannot find food, and flowers go unpollinated. These mismatches threaten entire ecosystems.

Unexpected reactions to cold spells

The study also revealed that plants and insects react differently to extreme weather. While extreme cold in spring caused butterflies and moths to emerge early, plant flowering times remained largely unchanged.

“Those kinds of phenological mismatches are going to have consequences for both the plants as well as for the insects, causing both populations to suffer,” Li said.

Future research on extreme weather

Li and his co-authors, Michael Belitz, Lindsay Campbell, and Robert Guralnick from the University of Florida, believe incorporating extreme weather into climate models will improve predictions. This could help mitigate negative effects on ecosystems.

“This work has the potential to be relevant across multiple sectors, from conservation to food security,” said Campbell, an assistant professor at the Florida Medical Entomology Laboratory.

“We are still just beginning to more fully understand how extreme weather impacts insects and plants, which ultimately impacts us and our food security,” said Guralnick. “This work is a step towards that goal.”

The study is published in the journal Nature Climate Change.

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