Effects Of Different Land Management Regimes On Protozoan Densities In Poplar Plantation

Protozoa are the simplest eukaryote but protozoa are a highly complex unit of living organisms.It is an important part of the regulation of microbial communities in the underground food web and its own community structure also varies due to the changes in the composition of the underground food web.Soil carbon pools are affected by protozoa due to their regulation of microbial communities.Under the background of global change,the decline of carbon storage and biodiversity and the weakening of soil ecological service function in agriculture and forestry ecosystem,the impact of land management on ecosystem has been aroused people's attention.In this paper,the effects of biological factors(microbial biomass,total fine root biomass,litter),vegetation diversity,soil properties were studied under the conditions of five different land management regimes(i.e.two levels of organic fertilization,two levels of inorganic fertilization and weeding treatments)effect on the protozoan community,the results are as follows:(1)In the natural condition,the density of protozoa in poplar plantations of northern Jiangsu coastal areas conformed to the density characteristics of protozoa in typical subtropical zones,densities of three major groups protozoa show the trend Flagellates > Amoebaes > Ciliates.(2)The application of two levels of organic fertilizations compared to the control treatment significantly increased the total density of protozoa,the density of Flagellates > Amoebaes > Ciliates.There was no significant difference in the total density of protozoa between 0-10 cm soil layer and 10-20 cm soil layer between two levels of organic fertilizer,but which change protozoa's habit of gathering close to the surface.No interaction was found between the two levels of organic manure on seasonal variation of amoebae.OM1 treatment and OM2 treatment of flagellates density was no significant difference,OM1,OM2 compared to CK treatment significantly increased the flagellate density.There was interaction between two levels of organic manure on seasonal variation of amoebae and flagellates.The application of two levels of organic fertilizers significantly increased soil microbial biomass,litter and total fine biomass compared to the control treatment.(3)Two levels of inorganic fertilizers did not cause differences in the total density of the three major groups of protozoa but reduced the soil protozoa density in the 10-20 cm soil layer;Two levels of inorganic fertilizers did not change protozoa's habit of gathering close to the surface;The level of inorganic fertilizers significantly increased soil microbial biomass,litter and total fine root biomass compared to the control treatments.(4)Weeding treatment reduced the density of protozoa in 10-20 cm soil layer and also reduced total density of soil protozoa;Weeding treatment did not change protozoa's habit of gathering close to the surface.(5)The total density of protozoa,the density three major groups of protozoa were positively correlated with microbial biomass C and microbial biomass N,and were not related to the total root biomass.The density of total protozoa,Amoebaes,Flagellate was significantly correlated with plant litter.The density of three major groups of protozoa in June was positively correlated with the Shannon-Wiener index of aboveground vegetation in June.The densities of meat Amoebaes,Flagellates,total protozoa were significantly negatively correlated with soil pH,significantly positively correlated with soil organic matter.The density of Amoebaes,Flagellates was positively correlated with soil available phosphorus.Above all,our results indicated that inorganic and organic fertilization increase the total density of protozoa,except low levels of inorganic fertilization,fertilizations management promote microbial growth,increased soil organic matter,that will be better for the maintenance of soil fertility;Weeding treatment reduced the total density of protozoa and it is not conducive to soil microbial growth,what is more,it reduced the soil organic matter which is not conducive to soil fertility to maintain.