Preliminary study on the biomass and the carbon storage in karst grassland in Liujiang Basin, Guangxi

Grassland is one of the largest terrestrial ecosystem types and plays an important role in the global carbon cycle. Studies on biomass of karst grassland are rare that making the estimation on carbon storage inaccuracy because of lack of data. According to the average height and distribution areas, three representative karst grassland types in Liujiang Basin are chosen to estimate community biomass by harvest method. The results show that (1) total biomass of Miscanthus floridulus, Arundinella hirta and Eremochloa ophiuroides is 8 609.68 g/m2, 1 022.61 g/m2 and 821.63 g/m2 respectively. Biomass and height are positively correlated, while above-ground biomass increases faster than the below-ground one; (2) the relation of below-ground biomass to above-ground biomass varies from 0.21 for Miscanthus floridulus to 1.91 for Eremochloa ophiuroides, and shows a negatively correlation with community height. The ratio of below-ground biomass (y) and above-ground biomass (x) is well fit with power functions of y=1.7352x0.9062 for Arundinella hirta and y=5.3076x0.4466 for Miscanthus floridulus (R2> 0.79, P <0.01). Above-ground biomass accumulates rapidly with the increase of community height; (3) below-ground biomass decrease with depth and is well fit with power function model (R2＞ 0.95, P ＜0.01). Most of below-ground biomass distributes in 0～20cm soil layers; (4) the carbon storage of grassland in Liujiang Basin is calculated as 9.51 TgC.