Study on biomass dynamic change of Rhododendron-Larix gmelinii forests after fire disturbance

Abstract

Applying space sequence instead of temporal change, Rhododendron-Larix gmelinii forests's biomass distinctive responses at different successional stages after fire disturbance to varying degrees have been sysmatically studied at Daxing'an Mountains. The results show that: the ground biomass in the community increase progressively with recovery time after fire disturbance to varying degrees. At the early grass or shrub stage after high-intensity fire disturbance, the entire biomass are mainly comprised of biomasses from herb layer and shrub layer; suffering high-intensity fire disturbance after nineteen years or so, the most biomass mainly come from trees layer and the situation will last until the ultimate stage; when suffering middle-intensity fire disturbance, arbor layer, successional layer, shrub layer and total biomass in the forests will steadily increase with recovery time while herb layer decline by degrees. Almost all the biomasses mainly come from trees layer after ten years when fired; the low-intensity fire disturbance have less effect on the accumulation of all the layers, which illustrate that the proportion of biomass coming from respectively different layers remain almost unchanged in the whole biomass. Fire disturbance have varying effects on accumulation of biomass: As the recovery time advances, the ability of accumulating litter restore. This includes slowest restoring rate after high-intensity fire disturbance and fastest restoring rate after low-intensity fire disturbance. Meanwhile, the bare land after low-intensity fire disturbance provide a good opportunity for seed to contact with soil and accelerate the recovery of Rhododendron-Larix gmelinii forests; at different successional stages after fire disturbance, the wilted fell leaves have a larger proportion in all the litter. The proportion to which the conifers' fell leaves has the broads' could reflect characteristics at successional stages.