Plant functional composition as an effective surrogate for biodiversity conservation

In biodiversity conservation frameworks, determining surrogates for biodiversity is crucial for improving the effectiveness of biodiversity conservation and management. As plant functional composition can indicate variations in ecosystem functions and services, it could be used as an effective surrogate in biodiversity conservation planning. However, to the best of our knowledge, this metric has been rarely used in biodiversity conservation planning. To explore whether plant functional composition can be used as an effective surrogate for biodiversity conservation, we used a linear mixed regression model to investigate the relationships between plant functional composition (i.e., community-weighted means (CWMs) from the sPlot database) and the species richness of birds, mammals, and amphibians, and between plant functional composition and terrestrial conservation priority ranks (considering biodiversity conservation alone, or biodiversity, carbon, and water conservation together). Thereafter, we quantified the changing trends in these relationships across biomes using the least square method. We found that CWMs significantly affected species richness and terrestrial conservation priority ranks, based on the marginal R2 and conditional R2 values from the linear mixed regression model. Further, CWMs significantly affected species richness and terrestrial conservation priority ranks across different biomes of forests and shrublands. However, the nature of these effects (i.e., positive or negative) was dependent on biome type. These results suggest that functional composition can be considered as a biodiversity surrogate for conservation planning, and that biome-specific relationships should be considered.