Linking Tree and Shrub Biomass to Plant Diversity During Early-Stage Alpine Afforestation

Area of Science:

• Ecology
• Restoration Ecology
• Alpine Ecology

Background:

• Afforestation is crucial for restoring plant diversity, ecosystem functions, and services.
• Significant knowledge gaps exist regarding the performance and drivers of early-stage alpine afforestation.
• Understanding factors influencing plant diversity is essential for successful ecological restoration in alpine environments.

Purpose of the Study:

• To investigate the effects of tree and shrub biomass on species diversity (SD) and phylogenetic diversity (PD) in early-stage alpine afforestation.
• To analyze these effects at both plot (1x1m²) and site (10x10m²) spatial scales.
• To provide empirical data for optimizing tree species selection and planting practices in alpine regions.

Main Methods:

• Employed a general linear mixed model (GLMM) to assess associations between tree/shrub biomass and diversity indices.
• Evaluated multiple diversity metrics: Shannon, Simpson's, species richness, Pielou's evenness, Faith's PD, and net relatedness.
• Data collected from 78 sites, each with five 1x1m² plots, across two spatial scales.

Main Results:

• Both tree and shrub biomass significantly influenced plant diversity at both plot and site scales.
• The relationships between biomass and SD/PD were non-linear.
• At the site scale, species evenness peaked with median tree biomass. At the plot scale, shrub biomass negatively correlated with Shannon index, species richness, and Faith's PD.

Conclusions:

• Biomass impacts on species and phylogenetic diversity are scale-dependent and influenced by plant life form (tree vs. shrub).
• Findings highlight the efficacy of ecological restoration through alpine afforestation.
• Results offer a novel empirical basis for selecting tree species and planning planting strategies in alpine ecosystems.