关键词: 细根生物量, 吸收根, 空间分布, 垂直分布, 吸收效率

Abstract: In order to reveal the relationship between plant root growth strategy and the environment and the contribution of fine root turnover to grassland soil carbon pool, the authors sampled root to one meter soil depth at 17 sites across the desert grasslands, typical grasslands and meadow grasslands across Inner Mongolia, and lowerorder roots were separated from total root. The results showed that 1) lower-order root biomass was positively correlated with total root biomass, and both lower-order root biomass and total root biomass were positively related to annual average precipitation and soil nitrogen content, negatively related to annual average temperature; 2) the ratio of lower-order root biomass to total root biomass showed a trend of desert grassland (14%) < typical steppe (20%) < meadow steppe (39%), and the ratio was positively related to average annual rainfall, negatively related to annual average temperature and not related to soil carbon and nitrogen content; 3) the vertical distribution patterns of lower-order root biomass and total root biomass were similar: decreasing with soil depth in meadow grasslands with 85% of the biomass distributed in the 0–40 cm layer, while not significantly differented among soil layers in typical grasslands and desert grasslands. This study suggested that 1) plant roots could response the two environmental factors through different mechanisms; 2) in habitats with lower water availability, plants might allocate less C to the lower-order roots to reduce C loss, and allocate more C to higher-order roots to store water and nutrient. It is further suggested that fine root absorption efficiency may be higher in drier habitats than moister habitats.

Key words: fine root biomass, absorptive roots, spatial distribution, vertical distribution, absorption efficiency