Drop in rain forest productivity could speed future climate change

Drop in rain forest productivity could speed future climate change


Landscape-scale aboveground productivity (ANPP*) and its components at La Selva, Costa Rica, through the 21-year study period. Error bars indicate ±1 S.E.M for each 18-plot mean. X-axis: Year 2 of each measurement-year. Credit: DOI: 10.1029/2021JG006557

Tropical forests host a rich diversity of plant and animal life and process vast amounts of carbon dioxide (CO2). Therefore, researchers have been particularly interested in how these ecosystems might be affected by climate change. Some have hypothesized that the rise in atmospheric CO2 is promoting carbon uptake by these forests, making them important carbon sinks. Evidence is mounting, however, that the balance of cost and benefit is reaching a tipping point, and global warming will soon hinder tropical forests’ ability to soak up carbon.

In a new study, Clark et al. assessed ‘ annual net primary productivity from 1997 to 2018. They measured wood growth and litterfall in 18 plots in Costa Rica’s La Selva Biological Station. The scientists collected litterfall every other week from basket traps and annually measured the growth of all live stems greater than 10 centimeters in diameter. They found that the stress associated with outweighed the benefits of increased carbon dioxide. Annual aboveground net primary production fluctuated greatly year to year, but no productivity component increased over the 21 years. Twig litterfall declined, and wood production suffered in years with slightly warmer nights and with particularly hot dry seasons.

The new research provides further evidence that as nighttime temperatures continue rising and as more daytime hours exceed the optimum temperature for photosynthesis, productivity will decline. The authors warn that tropical forests could soon enter into a positive feedback loop that accelerates both and tropical forest decline. As forests become less productive because of rising temperatures, they will soak up less carbon dioxide, which in turn will lead to more warming. This cycle could pose a major threat to the survival of these highly biodiverse ecosystems.


Dramatic liana increases in old-growth tropical forests associated with natural disturbance and climate change


More information:
Deborah A. Clark et al, Annual Tropical‐Rainforest Productivity Through Two Decades: Complex Responses to Climatic Factors, [CO 2 ] and Storm Damage, Journal of Geophysical Research: Biogeosciences (2021). DOI: 10.1029/2021JG006557

This story is republished courtesy of Eos, hosted by the American Geophysical Union. Read the original story here.

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Drop in rain forest productivity could speed future climate change (2022, January 12)
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