| Phyllostachys praecox is one of the main economic bamboo species in the south of China,because of its economic,social and ecological functions,it's planting area has expanded continuously.Reasonable mulching management not only can improve the productivity of phyllostachys praecox,but also can maintain the sustainable development.The past research about phyllostachys praecox mulch technology focused on how to improve the productivity most,but with the growing interested in the ecological functions of bamboo,economic functions and ecological service function developed together become the main direction of the develop.Therefore,it is important to study the influence of long-term mulching management on phyllostachys praeco for sustainable development.The samples were collected form Phyllostachys praecox stands with different mulching age(0,3a,6a,9a,12a)in the town of Jinshan,Yuhang,Zhejiang Province.Analysis the bamboo's biomass,shoot output and High Throughput Sequencing were used to characterize the diversity of soil bacteria.Analysis the phyllostachys praecox stand degeneration degree,aims to reveal the effect of mulching management on phyllostachys praecox forest.Provide the theory and technical guidance for the sustainable management of phyllostachys praecox and prevent the degradation of bamboo forest.The main results were as follows:At the initial stage,the soil pH showed no significant difference.At the 12 years of mulching,soil pH value was from 5.23(0a)fell to 3.42.After the mulching,soil organic matter and N,P 's content is increasing.The increasing of organic matter,total P,available P's content were 52.4%,71.6%,64.3%.the increasing of total N's content were 95.6%.After the 3 years of mulching,Soil organic matter increased significantly,but the increase of organic matter after 6 years mulching management tend to be gentle;the content of P and N in soil has been maintained a high growth rate.There were 280548 bacterial 16 S rDNA sequences and 598 OTU types obtained respectively from the soil samples.The diversity(Shannon Wiener Index)and abundance(Ace Index)of soil bacterial community showed a higher difference among different mulching ages.At the initial stage Shannon Wiener index and Ace showed increasing tendency with the mulching age.These indexes reached the maximum at 6 years of mulching.After that time these indexes showed a decline.The dominant bacterial communities at phyum level were Proteobacteria,Acidobacteria and Actinobacteria,and their relative abundance were more than 70%.At the soil without mulching management,The dominant bacterial communities at class level were Acidobacteria,Actinobacteria,Ktedonobacteria,after 12 years of mulched,the dominant bacterial communities were Alphaproteobacteria,Actinobacteria,Acidobacteria.The most abundance genus were Gp1,Gp2 and Acidipila.The relative abundance were 11.55%,6.27% and 3.28%.Study showed that the mulching management had a marked influence on the structure and diversity of soil bacterial communities.Gp1 belongs to the Acidobacteria,is a kind of acidophilus,after the mulching,soil shows the trend of acidification.The abundance of Acidobacteria should be increased,but in this study the trend is decrease.The relative abundance of Gp1 decreased from 11.77%(CK)to 3.95%(9a).The relative abundance of Thermosporothrix decreased from 6.60%(CK)to 0.28%(9a).Thermosporothrix mainly uses the light to produce energy.Changes in the illumination condition of the forest after mulching may be the main reason for the decrease of Thermosporothrix.The biomass accumulation level of the different parts of bamboo was: culm >leaf >branch>pocket.From the 0 years to the 3 years,the biomass of culm showed a large number of accumulations.The biomass of leaf and branch mulching from 0 to 3 years without significant increasing,but after 3 years,appeared varying degrees of decline.The biomass of bamboo pocket didn't change a lot with the mulching management.Bamboo leaves biomass has been at a high level in the early stage of mulching,which may be the main factors affecting the sustainable growth of bamboo biomass during the period of 0 to 3 years.The biomass of leaf and branch showed downward trend to reduce the productivity of bamboo,bamboo forest biomass appeared a tendency of decline.The statistics of the different mulching periods of bamboo rhizome biomass shows that: in the early mulching periods,rhizome is mainly distributed in 20 ~ 30 cm soil layer,the total weight were 10200 kg·hm-2,accounted for 87.17% of the total weight of the whole soil.After a period of mulching,rhizomel tend to the soil surface distribution.In the 0 years,the biomass of rhizome in the 0~20cm were accounted for 36% of total weight.The bamboo of rhizome in the soil mulching with 3 years,6 years,9 years were 70.42%,73.52% and 74.67% in the 0~20cm.After 12 years of mulching,in the 20 cm soil layers almost no rhizome distribution.In the study plots,the shooting period of the stand without mulching is from late February to early April,lasting 42 days.Between March 10 th and March 30 th,the average daily shoot output was 266.75 kg· hm-2.The stand mulching with 3 years and 6 years 's shooting periods is from late February to late December,the average daily shoot out put were 340.22 kg· hm-2and 268.5 kg· hm-2.The stand mulching with 9 years and 12 years 's shooting periods is from mid December to early March,the average daily shoot out put were 256.26 kg· hm-2and 223.74· hm-2.Compared with the non-mulched bamboo forest,the shoot out period was longer in the soil with the mulching management.The shoot outputs have been improved in the soil mulching from 3 years and 12 years.But after 3yeara the shoot output were declined. |
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