FINE-ROOT PRODUCTION AND MORTALITY IN DEGRADED VEGETATION IN HORQIN SANDY RANGELAND IN INNER-MONGOLIA, CHINA

The total root biomass of an Artemisia halodendron plant community was measured several times during the growing seasons of 1989-1991 using soil coring. Root growth was measured with ingrowth mesh bags. Fine-ro ot production was calculated based on increases in biomass estimated w ith soil coves and mesh bags. Root growth dynamics of Artemisia halode ndron and Caragana microphylla were measured using minirhizotrons. An alternative estimate of fine-root production was made based on root gr owth measurements from minirhizotrons and biomass estimates from soil cores. During the dry growing season of 1989, root biomass increased s ignificantly. However, during the wet growing seasons of 1990 and 1991 , no significant changes in root biomass were found. On the other hand the minirhizotron method revealed that root numbers changed rapidly a nd significantly during both wet years. Current-year root biomass in t he mesh bags reached a maximum of 56 g m(-2). Estimates of annual fine -root production to 35-cm depth varied between zero and similar to 250 g m(-2), depending on the method used. Methodological aspects were di scussed, and it was concluded that true root production probably was c loser to the upper than to the lower estimate.