Tropical forest restoration: Fast resilience of plant biomass contrasts with slow recovery of stable soil C stocks

Background

The study looks at three land-use types: 1) land left barren after a clear-cut in the 1950s, with only a sparse cover of shrubs, grasses, and vines, 2) a Eucalyptus exserta plantation established in the 1960s, and 3) a eucalyptus plantation that was clear-cut in 1974 and converted into a plantation of native tree species, now considered a secondary forest. The biomass and soil carbon (C) of these three land-use types were compared to a nearby natural old-growth forest.

Conclusions & Takeaways

The study found that, similar to other studies in neotropical forests, Asia's tropical secondary forests reach 86% of a natural forest's biomass after 50 years of restoration. Secondary forests have similar surface C to natural forests; however, most of the secondary forests' surface C is new C. Meanwhile, secondary forests have higher surface C than the eucalyptus plantation; however, the proportion of their old C content was about equal. Secondary forests have much less deep soil C to natural forests. Overall, natural forests have much higher soil C than secondary forests (97.42 t/ha to 58.75 t/ha). This indicates that secondary forests' soil C are coming from the new vegetation cover and remaining in the soil surface; longer times are required to replenish C in deeper soils.