Urban warming reduces aboveground carbon storage

Area of Science:

• Ecology
• Urban Forestry
• Climate Change Biology

Background:

• Mature trees store substantial global carbon.
• The impact of warming on mature tree carbon storage remains experimentally untested.
• Urban ecosystems face unique environmental pressures.

Purpose of the Study:

• To investigate the effects of urban warming and insect herbivory on mature tree physiological function and carbon sequestration.
• To quantify the impact of urban warming on the rate at which trees store carbon annually.

Main Methods:

• A citywide, factorial experiment was conducted.
• The study examined the combined effects of warming and insect herbivory.
• Physiological function and carbon sequestration rates of mature trees were measured.

Main Results:

• Urban warming increased the abundance of herbivorous arthropods on trees.
• Insect herbivores had minimal impact on tree carbon sequestration.
• Urban warming was linked to an estimated 12% loss in carbon sequestration.
• Reduced photosynthesis at hotter sites contributed to the loss of carbon sequestration.

Conclusions:

• Urban warming negatively affects mature tree carbon sequestration.
• Current ecosystem service assessments may overestimate urban tree carbon storage.
• Future urban warming is predicted to further decrease carbon sequestration by urban trees.