Data and code from: Biodiversity–carbon relationships diverge in forests dominated by different species within the same plant functional type

Theoretical and experimental evidence suggests that tree biodiversity
enhances forest ecosystem functioning. However, whether these
relationships hold within forest types dominated by different species of
the same plant functional type remains unclear. We analysed 772 plots in
subtropical China, contrasting high- and low-carbon-sequestration
plantations of Cunninghamia lanceolata and Pinus massoniana along a
chronosequence, to explore causal links among aboveground carbon storage
(AGC), biodiversity, stand structure, and environmental factors. We found
that the effects of biodiversity on AGC varied across forest types.
Specifically, species diversity and functional diversity enhanced AGC in
high-carbon-sequestration C. lanceolata plantations, whereas species and
functional diversity of co-occurring broadleaf species had negative
effects. In high-carbon-sequestration P. massoniana plantations,
phylogenetic diversity and diameter at breast height (DBH) variation
positively influenced AGC, outweighing the negative effects of species
diversity. Low-carbon-sequestration plantations exhibited weak or
non-significant biodiversity–AGC relationships. Additionally, soil
attributes directly reduced AGC in low-carbon-sequestration C. lanceolata
plantations, indicating nutrient limitations under intensive management.
We demonstrate that biodiversity–ecosystem functioning relationships
diverge among forest types dominated by different species within the same
plant functional type, and that biodiversity effects on AGC vary across
these plantations. In soil-limited conifer plantations (C. lanceolata),
increasing species diversity enhances AGC, whereas in light-demanding
conifer plantations (P. massoniana), phylogenetic diversity and DBH
variation, capturing species similarity and niche occupancy, better
explain AGC than species or functional diversity. We advocate for tailored
management strategies that consider dominant tree species identity to
optimise biodiversity and carbon sequestration.