Will drought exacerbate the decline in the sustainability of plantation forests relative to natural forests?

Abstract

Occupying 7% of the World's forest area, plantation forests have been increasing globally for the past 30 years and serve as a natural climate solution. However, whether plantation forests share the same fate as natural forests under the changing climate remains an open question. By establishing a framework in which climate directly and indirectly triggers or exacerbates fire and pests to affect forest vitality, we compared the vitality and resilience of 705 large plantation patches and 187 large natural forest patches over the past 20 years in China. Overall, large patches of plantation forests showed consistent sustainability with natural forests across China and were mainly distributed in humid areas with the fewest and weakest droughts. Forty percent of the vitality decline of natural forests was explained by droughts, pests, and fires driven by climate, while 70% of the vitality decline of plantation forests was affected by a combination of these disturbances through different pathways. As the site environments became drier, an increasing number of plantation forests showed lower vitality relative to natural forests. Frequent and serious droughts not only magnified the direct impact of drought on plantation forests, possibly due to homogeneous forest structure regarding ages and species, but also exacerbated forest fires and caused lower vitality of 85% of plantation forests relative to natural forests in southwest China. The work highlighted threats to the sustainability of plantation forests in site environments with frequent drought, challenging the efforts of expanding plantation forests.