5. Conclusions
Forest degradation is increasingly recognized as a major threat to
global biodiversity and ecosystems’ capacity to provide ecosystem
services. This study contributes to our understanding of the impacts of
forest degradation on soil quality and function in SDTFs. Whereas
previous studies of this ecosystem have focused on the effects of
land-use conversion on soils, particularly agriculture, our study is
among the first to examine soil impacts of forest degradation resulting
from chronic disturbance. The effects of forest degradation might not be
as obvious as those from deforestation, but understanding them is as
important for ensuring ecosystem integrity and resilience as fathoming
the impacts of land-use change.
Our findings showed a consistent and steady reduction in soil quality
and function that paralleled the loss of vegetative structure and
diversity along a gradient of SDTF degradation. Above and belowground
conditions were clearly linked in the different forest states and
between seasons. This implies that while degradation can drive the loss
of soil C, N and enzymatic activity through the depletion of vegetation
biomass and richness, well-designed restoration strategies can help
reverse those losses.
The case of arid land, however, suggests that extreme forest degradation
could lead to an alternate state in which critical biochemical pathways
cease to function. Diminished soil quality, low enzymatic activity, and
a high POC/MAOC ratio suggested that this state lies beyond a critical
threshold of ecosystem resilience and requires serious intervention to
recover soil functionality. The question as to whether continued
disturbance to this state would lead to desertification requires urgent
attention.