Understory biomass and its characteristics as affected by forest gap in the alpine forest ecosystem in west Sichuan
Understory vegetation and its debris, as an important component in the forest ecosystem, can be greatly affected by forest canopy. As yet, little information has been available on the effects of forest gaps on understory plant and its debris biomass. In order to understand the changes of understory plant and its debris biomass as affected by forest gaps, therefore, three 100 m×100 m plots were sampled in a Minjiang fir (Abies faxoniana) primary forest ecosystem around 3 600 m altitude in western Sichuan in August, 2013. Coarse woody debris with length/height, basic diameter, diameter at breast height and decay class were investigated in each of three 20 m×20 m sampling quadrats in forest gap center, gap edge and closed canopy, respectively. Fine woody debris and shrub biomass were investigated in each of three 5 m×5 m sampling quadrats in forest gap, gap edge and closed canopy, respectively. Moreover, non-woody litter and herb biomass were harvested in each of three 1 m×1 m sampling quadrats in forest gap, forest edge and closed canopy, respectively. Each of 20 cm×20 cm sampling quadrat was randomly selected to harvest groundcover vegetation biomass in the above 1 m×1 m quadrat. The results indicated that:(1) the total biomass was 72.75 t·hm-2 in the sampled alpine forest ecosystem, and understory biomass was 67.92 t·hm-2 which accounted for 95.17%of the total biomass in whole ecosystem. Shrub biomass was 9.81 t·hm-2 and occupied the majority proportion of living vegetation, but coarse woody debris biomass was 53.00 t·hm-2 and occupied the majority of dead debris. (2) Shrub, herb and groundcover vegetation biomass showed different responses to forest gap. Shrub biomass was significantly higher in forest edge than that in closed canopy, although the biomass of groundcover vegetation was relatively lower in forest gap and forest edge compared with that in closed canopy. (3) Coarse woody debris biomass showed a decrease tendency from closed canopy to gap center, but the storage of fine woody debris in gap center and forest edge was larger than that in closed canopy. These results provide efficient foundation in understanding the understory biomass and its pattern in these alpine forest ecosystems as well as understanding the important role of gaps.
alpine forestunderstory vegetationbiomassforest gap
国家科技期刊平台
NSTL
万方数据
维普
