Study On Soil Biological Character Of Willow Plantation

Plantation plays an important role in relieving the shortage of timber and promoting the production and construction of forestry in our country. However, with the increasing development of Chinese fir, masson pine and poplar, a series of problems, especially successive plantation, have negative effects on forestry production, such as the slow growth of trees, the recession of forestland’s fertility. Therefore, people have paid lots of attentions to do research about the change of soil fertility in plantation for these years. Willow plantation is one of the fast developing plantation, both of whose scale and area are ever-increasing. While there is little report about the willow plantation’s change of the soil fertility. In this situation, this thesis takes willow plantation in Lian Yungang as the research object, investigates and samples in the field and then analyse them in the lab, including analysing the variation of soil alkaline phosphatase, sucrase, urease, catalase in willow plantation for different ages, studying the change of Microbial biomass carbon and Microbial biomass nitrogen, illustrating the relationship between biological and physicochemical characteristics of willow plantation and revealing the biological characteristics of willow plantation, all of which provide materials for maintaining the soil fertility and sustainable development of plantation. The main results are as follows:1. In general, soil alkaline phosphatase, sucrase, urease, catalase,microbial biomass carbon and microbial biomass nitrogen all increase with the increasing age of willow plantation.The soil alkaline phosphatase, sucrase, urease and catalase of 1-year-old willow plantation are 2.60mg/g、83.47mg/g、1.87mg/g、3.78ml/g;the 4-year-old willow plantation are 3.16mg/g、106.42mg/g、2.49mg/g、3.82ml/g.The Microbial biomass carbon and Microbial biomass nitrogen of 1-year-old willow plantation are 120.75mg/kg 、 33.51 mg/kg; the 4-year-old willow plantation are 179.05mg/kg、43.98.2. The soil enzyme activity of plantation in different soil layers differ greatly. The vertical change of the activity of soil alkaline phosphatase, sucrase, urease and catalase is in the following: the upper(0~20cm)>the middle-level(20~40cm)>the lower(40~60cm),the activity of the soil enzyme decreases when soil deepens. The soil enzyme activity ofsame layer plantation in different ages increase with the growing of plantation, the order of soil enzyme activity is 4-year-old>3-year-old>2-year-old>1-year-old.The research shows that: the soil alkaline phosphatase in three levels of the 1-year-old plantation are 2.63 mg/g、1.66 mg/g、0.91 mg/g, the 2-year-old plantation’ are 2.56 mg/g、1.87 mg/g、1.14 mg/g, the 3-year-old plantation’ are 2.53 mg/g、2.23 mg/g、1.28 mg/g and the4-year-old plantation’ are 2.80 mg/g、1.95 mg/g、1.57 mg/g; the soil sucrase in three levels of the 1-year-old plantation are 88.72 mg/g、56.26 mg/g、21.97 mg/g respectively, the 2-year-old plantation’ are 88.58 mg/g、71.65 mg/g、25.76 mg/g, the 3-year-old plantation’ are 94.29 mg/g、70.79 mg/g、25.80 mg/g and the 4-year-old plantation’ are 92.11 mg/g、81.01 mg/g、39.73 mg/g;the soil urease in three levels of the 1-year-old plantation are 2.27 mg/g、0.98 mg/g、0.48 mg/g, the 2-year-old plantation’ are 2.23 mg/g、1.27 mg/g、0.62 mg/g,the3-year-oldplantation’are1.64mg/g、1.14mg/g、0.74mg/gandthe4-year-oldplantation’are2.19mg/g、1.74mg/g、1.05mg/g;comparatively,thechangeofthesoilcatalaseissmall,thesoilcatalaseinthreelevelsofthe1-year-oldplantationare2.56ml/g、2.57ml/g、2.43ml/g,the2-year-oldplantation’are2.56ml/g、2.58ml/g、2.4ml/g,the3-year-oldplantation’are2.5ml/g、2.57ml/g、2.47ml/gandthe4-year-oldplantation’are2.57ml/g、2.5ml/g、2.51ml/g3.theorderofmicrobialbiomasscarbonindifferentsoillayersis0~20cm>20~40cm>40~60cm,microbialbiomassnitrogenalsoshowsthattheupperandmiddlelayersarehigher,theloweroneislower.generallyspeaking,theyalldecreaseassoildeepens.thesoilmicrobialbiomasscarbonofthesameplantationlayerindifferentagesisthatthe4-year-oldplantation’isthebiggest,whilethe1-year-oldplantation’isthesmallest.thesoilmicrobialbiomasscarboninthethreelevelsofthe4-year-oldplantationare171.03mg/kg、111.25mg/kg、75.82mg/kg,comparedwiththecontrast,thecontentsincreaseby87.59%、171.70%、171.72%respectively.the1-year-oldplantation’are126.39mg/kg、79.11mg/kg、36.00mg/kg,comparedwiththecontrast,thecontentsincreaseby38.63%、93.20%、29.01%.thechangeofthesoilmicrobialbiomassnitrogenindifferentagesvaries,theupperlayerofsoilisundulatoryandirregular,whilethemiddle-levelandthelowerlayeraresimilartomicrobialbiomasscarbon,thatisthechangeincreaseswiththeincreasingageoftheplantation.4.thesoilenzymeactivityhasagreatchangeindifferentseasons.ingeneral,thesoilalkalinephosphatase,sucroseandureaseallpresentthatthecontentinsummerishigherthanthoseinspringandwinter;whiletheorderoftheactivityofcatalaseisspring>summer>winter.thecatalaseofallplantationsindifferentagesarealmostthesameinthesameseason,whilethesoilalkalinephosphatase,sucroseandureaseincreasewiththeincreasingageoftheplantation.forexample,thesoilactivityofalkalinephosphatase,sucroseandureaseofthe4-year-oldplantationinsummeris2.65mg/g,76.65mg/gand2.76mg/g,comparedwiththecontrast,comparativelyincreasingby20.87%,38.41%and110.43%.5.therulesofmicrobialbiomasscarbonandmicrobialbiomassnitrogenvaryindifferentseasons.theorderofsoilmicrobialbiomasscarbonissummer>spring>winter,whiletheorderofmicrobialbiomassnitrogenissummer>winter>spring;bothofthetwomicrobialbiomasselementsindifferentplantationsofthesameseasonincreasewiththeincreasingageoftheplantation.