Canopy ants are out in the cold in temperate forests

Area of Science:

• Ecology
• Animal Physiology
• Climate Change Biology

Background:

• Ants are crucial ecosystem engineers whose distribution is influenced by thermal physiology.
• Forests create vertical climate gradients, but temperate forest ant responses to these gradients are understudied.
• Seasonal temperature variations in temperate forests may uniquely affect ant communities compared to tropical forests.

Purpose of the Study:

• To investigate the thermal tolerance of ground-dwelling versus arboreal ants in temperate forests.
• To determine how seasonal changes and microclimates influence ant thermal physiology.
• To understand the climatic constraints on ant distribution across forest strata.

Main Methods:

• Collected ants from ground and canopy strata across different seasons.
• Measured ant thermal tolerance (cold and heat).
• Recorded concurrent air and nest temperatures to assess microclimates.

Main Results:

• Canopy ants exhibited broader thermal tolerance than ground ants, adapting to wider temperature ranges.
• Ants from both strata enhanced cold tolerance seasonally, but heat tolerance remained stable.
• Arboreal ants displayed lower tolerance to winter cold, contrary to expectations given their exposure.

Conclusions:

• Ant ecophysiology differs across the vertical forest gradient in temperate zones.
• Winter cold tolerance, not heat tolerance, appears to be a key limiting factor for canopy ants.
• Future climate warming with milder winters could potentially increase temperate forest canopy ant diversity.