Abstract
Afforestation and land use changes have turned Southern China into one
of the largest carbon sinks globally, which sequesters carbon from the
atmosphere thus mitigating climate change. However, forest growth
saturation and available land that can be forested limit the longevity
of this carbon sink, and while a plethora of studies have quantified
vegetation changes over the last decades, the remaining carbon sink
potential of this area is currently unknown. Here, we train a model with
multiple predictors characterizing the heterogeneous landscapes of
Southern China and predict the carbon carrying capacity of the region
for 2002-2017. We compare observed and predicted carbon density and find
that during two decades of afforestation, 2.34 Pg C have been
sequestered between 2002 and 2017, and a total of 5.32 Pg carbon can
potentially still be sequestrated. This means that the region has
reached 75% of its carbon carrying capacity in 2017, which is 12% more
than in 2002, equal to a decrease of 0.83% per year. We identify
potential afforestation areas that can still sequester 2.39 Pg C, while
old and new forests have reached 87% of their potential with 1.85 Pg C
remaining. Our work locates areas where vegetation has not yet reached
its full potential but also shows that afforestation is not a long-term
solution for climate change mitigation.