Research for Stumping Technology and Utilization for Energy of Inefficient Caragana microphylla Lam Forest in Northwestern Shanxi Province

Caragana microphylla Lam,an shrub species,is very important to soil and water conservation,and sand-fixing afforestation.It also could be used as fuel and fodder.However,when stand age increases,some problems exist,such as the decrease of growth and benefit and so on.The 30-year-old plantation of Caragana microphylla in Pianguan,a county located in northwestern Shanxi Province,was selected as the study case.Through the comparison of growth index,biomass,and calorific value between 1~5 years′ growth after stumping;And the comparison between three habitats(the mild of shady slope,mild of sunny slope and beam hilly top) with three stumping methods(the height of stubble,covering soil or not,ribbon or massive stumping) the study aims to find a reasonable stumping technique to sustain the fuel type Caragana microphylla Lam.The results indicated:(1) five years later after stumping,plant height,basal diameter and number of branches were higher than CK by 20.96%,10.03% and 104.82%,single clump biomass reached to 2.89 kg/clump at most which was higher than the control stand by 25.65%,the total biomass per hectare of the stand reaches to 10 110~11 560 kg/hm2 which was higher than the control stand by 25.51%,the average annual biomass growth reached to 2 022~2 312 kg/(hm2·a) which was 7.8 times bigger than the control stand;(2) five stumping heights(2,5,10,15,20 cm) were used for treating three habitats,when stubble was 5 cm high,single cluster biomass reached to the highest level;s for oil covering and zonal or massive stumping,single cluster biomass difference was not significant.According to the results obtained above,stumping can be effective in promoting aged Caragana microphylla Lam forest rejuvenation.We suggest that reasonable level of stump management for the large area of aged Caragana microphylla Lam forest rejuvenation in northwestern China is the better way to orm a fuel style aging Caragana microphylla Lam forest.Especially for the degradation of agied of Caragana microphylla Lam forest,the stumping cycle should at least be five years;it is recommended that stubble height should be controlled as about 5 cm.