Temperate forests, especially those in the densely populated regions of
the world, are experiencing increasing levels of habitat degradation and
biological impoverishment due to subtle but pervasive chronic
anthropogenic disturbances including frequent and continuous grazing and
extraction of non-timber forest products. However, the effects of these
subtle, chronic disturbances on the biodiversity-productivity relationship
have rarely been examined especially in forests at different development
stages. Accordingly, this study explores how chronic anthropogenic
disturbance affects the relationship between tree species diversity and
forest productivity at different stand development stages in a large
temperate forest region. We used the human footprint index as a proxy
for chronic human disturbance. Hierarchical Bayesian models were employed
to assess the effects of chronic human disturbance on the relationship
between tree diversity and forest productivity across different stand age.
Several measures of diversity were employed, including taxonomic,
functional and phylogenetic diversity. Forest productivity consistently
increased with taxonomic, functional and phylogenetic biodiversity; these
biodiversity facets were the main drivers of forest productivity compared
to stand age, chronic human disturbance, and climate. However, the
magnitude at which productivity increases with the increments of taxonomic
and functional diversity diminishes with the increasing chronic
disturbance, especially in younger stands. The effects of phylogenetic
diversity on productivity did not vary with chronic disturbance,
regardless of stand age. Synthesis and applications: Chronic human
disturbance in a large temperate forest region reduces the increase in
community productivity due to different facets of biodiversity, especially
in young forests. The evidence suggests that the mitigation of chronic
human disturbance and the conservation of biodiversity will be effective
in sustaining essential ecosystem functions.