A positive diversity–productivity relationship has been demonstrated in
planned experiments, but the evidence from field studies of natural
forests is contradictory. We studied aboveground forest productivity in
28 subtropical montane forests on Mt. Fanjingshan and assessed the
relationship between productivity and tree diversity, as well as
climatic, edaphic, topography, and stand structural factors likely to
influence productivity. The main determinants of aboveground net primary
productivity (NPP) were climate factors and stand properties. They
explained 35% of the variance in NPP. The percentage of the variance in
NPP explained by stand properties, climate, soil properties, topography,
and species richness were 55%, 30%, 7%, 5%, and 3%, respectively.
Topography had no direct effect on production, but they had a
significant indirect effect. Elevation had an indirect effect on
production via tree height, and slope steepness had a significant
indirect effect through climate factors. However, tree diversity had
nonsignificant direct and indirect effects on productivity. We concluded
that the productivity of highly diverse montane forests is primarily
controlled by climate factors and stand structural properties rather
than species diversity.