5. Conclusions
In this study, we conducted experimental manipulations combining five
density gradients and six common species of different plant functional
types from grasslands in temperate China. Our results showed that the
amount of photosynthetic products allocated belowground for each species
was lower than that allocated aboveground, particularly for the annuals.
Among the different plant functional groups, the R/S of annuals is much
lower than that of perennials, suggesting that estimating the
belowground biomass of annual-dominant communities with the empirical
R/S of perennial plant communities in the field can induce large
uncertainties. The R/S of C4 plants is lower than that
of C3 plants, suggesting that the expansion of
C4 herbaceous plants may have large impacts on future
belowground C pool dynamics of grassland ecosystems in the future. The
allometric relationships between shoot and root biomass obtained in this
study were species-specific and could be modulated by density, which is
not in line with allometric partitioning theory. These findings
highlight the need to consider the effects of plant functional type and
density on above- and belowground biomass allocation patterns when
estimating and predicting the future belowground C dynamics of
grasslands in the context of climate change.