Limits on phenological response to high temperature in the Arctic

Area of Science:

• Ecology
• Plant Science
• Arctic Biology

Background:

• Tundra plants are typically limited by cool temperatures and short growing seasons.
• Phenological development in tundra ecosystems is often predicted using growing degree days (GDD).

Purpose of the Study:

• To investigate a modified growing degree day model incorporating a maximum temperature threshold for predicting tundra plant flowering.
• To understand the thermal responsiveness of tundra plants, especially in extreme cold environments.

Main Methods:

• Analysis of over ten years of seasonal flower counts for 23 tundra plant species.
• Utilized hourly canopy temperature records from four distinct plant communities.
• Developed and tested a modified growing degree day model with a maximum temperature threshold.

Main Results:

• Flowering timing for many tundra plant species is better predicted by a model including a maximum temperature threshold.
• Identified maximum temperature thresholds within the common daily temperature range for many species, particularly at high Arctic sites.
• Observed that passive experimental warming results in smaller shifts in plant phenology compared to ambient warming.

Conclusions:

• Maximum temperature thresholds are crucial for accurately predicting tundra plant phenology.
• Tundra plants adapted to extreme cold may have inherent limitations to their thermal responsiveness.
• Findings offer insights into the differential effects of passive versus ambient warming on Arctic flora.