Dynamic of Grassland Biomass in Different Degenerative Stages

摘要

The dynamics of plant community and above- and belowground biomass of the different degenerative stages was researched of Kobresia humlis meadows of Nakchu prefecture in Tibet Autonomous Region. The results indicated that the aggravation of the degreeof deterioration of alpine meadow is, the lower the vegetation coverage, percentage of excellent forage, and biodiversity are. The total aboveground biomass is highest in the lightly degraded stages while it is lowest in the extremely degraded stages. With the aggravation of degradation, the aboveground biomass of forbs increases while that of Cyper-aceae decreases. We found that the belowground biomass was mostly distributed in the 0-10 cm soil depth in the alpine meadow with a "T"-shape distributionfeature, and with the acceleration of deterioration, the numbers of roots becomes less and less. Meanwhile, the above- and belowground biomass of the different degraded communities was significantly correlated (r=0.963). There is an obvious positive correlation with the above- and belowground biomass in different degenerative stages, and their ratio increased with the aggravation of degradation.