Aboveground biomass production and dominant species type determined canopy storage capacity of abandoned grassland communities on semiarid Loess Plateau

Quantifying canopy storage capacity and its temporal variation is necessary for evaluating the ecohydrological effects of grassland restoration. In this study, four grassland communities after abandonment of 2, 7, 15 and 30 years on the semiarid Loess Plateau were selected, and canopy storage capacities, canopy structures and species compositions were examined in the growth period (May to September). Canopy, living plant, standing litter and floor litter storage capacities ranged from 0.11-0.56, 0.030-0.51, 0.0070-0.079 and 0.013-0.21 mm, respectively, and all exhibited an increasing trend with restoration year. Canopy storage capacity, vegetation coverage and aboveground biomass reached the maximum in August. Standing and floor litter storage capacities had the highest correlations with their biomass weights. Species diversity reached the maximum in 15 years abandoned grassland, with no significant monthly change. Annual forb, annual grass, perennial forb and perennial forb/grass were the typical dominant species type of 2, 7, 15 and 30 years abandoned grasslands, respectively. Perennial forbs (Artemisia gmelinii, Lespedeza davurica) had higher water storage than those of annual forb (Artemisia capillaris) and grasses (Setaria viridis, Roegneria kamoji). Path analysis revealed that fresh aboveground biomass and dominant species type mainly affected canopy storage capacity. No significant correlations were found between storage capacity and species diversity indexes. These results highlighted the importance of vegetation aboveground biomass and species functional group for evaluating grassland hydrological function and adopting suitable restoration strategy.

Automated summary

The study found that canopy and litter storage capacities increased with the abandonment time of the grassland. Dominant species type and aboveground biomass had a significant impact on canopy storage capacity, while there was no significant correlation between species diversity and storage capacity indexes.