Severe Droughts Affect Forests And CO2 Storage for Years, Study Shows

Severe drought can affect a forest’s growth for up to four years, a period during which it is less effective at removing carbon
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A stressed forest in the southwestern United States
from the atmosphere, a new study reports in the journal Science. Standard climate models have assumed that forests and other vegetation bounce back quickly from extreme drought, but that assumption is far off the mark, the researchers say. Looking at data from more than 1,300 forest sites dating back to 1948, they found that living trees took an average of two to four years to recover and resume normal growth rates after droughts ended. Frequent droughts in places like the western U.S. could significantly impact the ability of forests to sequester carbon, the study found. Researchers aren’t sure how drought causes these long-lasting changes, but they say there are likely three causes: Loss of carbohydrate and foliage reserves may impair growth; pests and diseases may accumulate in drought-stressed trees; and lasting damage to vascular tissues impairs water transport.