Long-term protection in grasslands enhances soil carbon storage via reduced disturbance and community trait diversity-environment adaptations

Understanding how ecological disturbance and plant community traits
regulate soil carbon storage is critical for predicting ecosystem
feedbacks to global change and designing sustainable land-use strategies.
However, the processes by which disturbance regimes mediate the trade-offs
between species preservation and soil carbon storage are difficult to
predict due to their complexity and remain debated, particularly in
comparison to protected systems. We employed a paired-site design,
sampling 30 long-term managed grasslands and their paired nature reserve
counterparts across a gradient of three grassland types (wet, mesic, and
dry) in Central Europe (Czechia). At each site, we quantified soil carbon
stocks, characterized soil chemical properties, measured aboveground
biomass production, and assessed plant community composition through
species diversity and functional trait analyses. We found that protected
grasslands store significantly more carbon than their conventionally
managed counterparts, driven by reduced anthropogenic disturbances, which
promote ecosystem stability and enhance nutrient retention, coupled with
plant community traits that favour carbon storage. Our results show that
dry grasslands accumulated more carbon than mesic or wet types, likely due
to trait-mediated stabilization and constrained microbial activity under
aridity. Despite higher biodiversity in protected areas, soil carbon
stocks were uncorrelated with species richness, revealing a potential
indirect decoupling of species richness and carbon sequestration. Notably,
biomass-carbon correlations persisted in managed grasslands but vanished
in protected systems, indicating divergent dynamics of productivity from
storage under undisturbed conditions. The environmental indicators
predicted carbon stocks in protected grasslands, whereas managed systems
relied on community characteristics and acquisitive traits. This study
demonstrates that protected grasslands support both richer biodiversity
and larger soil carbon stocks compared to commercially managed sites. The
findings that underscore the ecological benefits of sustained protection
and limited disturbance, providing valuable insights for land management
and restoration strategies within existing conservation programs that
integrate biodiversity protection with carbon sequestration, such as the
Natura 2000 Network.