| In the process of forest disease and pest prevention, pesticides could effectively curb the spread of the forest diseases and pests but also caused pollution on forest soil ecosystem. In forest soil, the residues of pesticide not only worsen the soil environment, change the soil physical and chemical properties, but also greatly affected the forest ecological benefits. Soil microbial is an important part of forest ecosystem, which could sensitive indicate the soil quality, has been widely used to evaluate the ecological security of pesticides. In this study, two kinds of Korean pine mixed forests (Abies nephrolepis and Tilia amurensis) and two kinds of artificial pure forests (Larix gmelinii and Betulla platyphylla) were taken as research object, chlorothalonil and fenvalerate were taken as test materials. Normal experiment technologies of soil science research were used to determine the influence of pesticides on soil physical and chemical properties, soil enzyme activity in four forest types. Dilution plate method and chloroform fumigation extraction method were used to determine the influence of pesticides on soil microbial quantity and soil microbial biomass.BIOLOG ECO micro plate method was used to determine the influence of pesticides on soil microbial community functional diversity. Gas chromatography was used to analysis the dynamic of pesticides residues and degradation in four kinds of forest types. The results show that:fenvalerate1、Influence of pesticides on soil physical and chemical properties, soil enzyme activity(1) Compared with the check soil samples, there were no influence of chlorothalonil and fenvalerate on soil water content, soil organic matter content and pH value in four kinds of forest types.But in Abies nephrolepis and Betulla platyphylla forest hydrolysis of soil nitrogen, Available K and effective P were restrainted by chlorothalonil and fenvalerate. During the period of 0Month-2Months the inhibitory effect was the most significant; in lOMonths the inhibitory effect was disappeared.(2) Chlorothalonil and fenvalerate could influence the activit of urease, beta glucosidase, acid phosphatase and catalase. In OMonth soil enzyme activity were significantly decreased, but with the succession of time, the inhibitory effect of the pesticides on soil enzyme activity was weakened and even disappeared.(3)In four forest types, soil physical and chemical properties was closed correlated with urease, beta glucosidase, acid phosphatase and catalase, but the correlationship was difference in four foeset types.2, Influence of pesticides on soil microbial quantityIn Abies nephrolepis and Tilia amurensis forest there were no significant influence of chlorothalonil and fenvalerate on soil microbial quantity. During the period of 0Month-10Months the bacteria numbers of Larix gmelinii forest was restrainted by chlorothalonil and fenvalerate, during the period of 0Month-2Months the bacteria number in Betulla platyphylla forest was also restrainted by chlorothalonil and fenvalerate.During the period of OMonth-2Months, fungus numbers of Abies nephrolepis and Tilia amurensis forest were restrainted by chlorothalonil. During the period of OMonth-10Months, fungus numbers of Betulla platyphylla forest were restrainted by chlorothalonil. Fenvalerate restrainted Abies nephrolepis and Betulla platyphylla forest fungus numbers during the period of 0Month-2Months, restrainted Tilia amurensis and Larix gmelinii forest fungus numbers during the period of 0Month-10Months.During the period of 6Months-10Months chlorothalonil promoted the numbers of actinomycetes in Abies nephrolepis, Tilia amurensis and Larix gmelinii forest, but restrainted the numbers of actinomycetes in Betulla platyphylla forest during 0Month-10Months. There was no influence of fenvalerate on the numbers of actinomycetes in Abies nephrolepis forest, but restrainted the numbers of actinomycetes in the other three kinds of forest types during the period of 0Month-10Months.3、Influence of pesticides on soil microbial biomassIn the check soil sample, the spatial distribution of soil microbial biomass carbon and nitrogen in the four forest types was surface soil layer>0-20cm soil layer. The time distribution of soil microbial biomass carbon was 10Months> 6Months> OMonth> 2Months, time distribution of soil microbial biomass nitrogen was 10Months> 0Month>6Months>2Months.Compared with the check soil samples, in the time distribution rule of soil microbial biomass carbon, chlorothalonil was restrainted soil microbial biomass carbon of Larix gmelinii forest in 0Month. On spatial distribution rule of soil microbial biomass carbon, chlorothalonil was restrainted soil microbial biomass carbon of Larix gmelinii forest in surface and 0-20cm soil layers. There was no significant influence of fenvalerate on the time distribution rule of soil microbial biomass carbon in four forest types, on spatial distribution rule of soil microbial biomass carbon fenvalerate could significantly promote the surface and 0-20cm soil layers soil microbial biomass carbon in Betulla platyphylla forest.In the time distribution rule of soil microbial biomass nitrogen, soil microbial biomass nitrogen in the four forest types were all restrainted by chlorothalonil in 0Month, On spatial distribution rule of soil microbial biomass nitrogen, soil microbial biomass nitrogen in the surface soil layer were restrainted. In 0Month-2Months, fenvalerate could restraint the soil microbial biomass nitrogen in Larix gmelinii and Betulla platyphylla forest.4、Influence of pesticides on soil microbial community functional diversity(1) Influence of pesticides on soil microbial AWCD valueIn the check soil sample, soil microbial AWCD value in the surface soil layer was higher than 0-20cm soil layer. The trend of soil microbial AWCD value in the surface soil layer was 2Months>10Months>0Month>6Months, in the 0-20 cm soil layer was 2Months>10Months >6Month>0Months, in different forest types was Tilia amurensis> Abies nephrolepis> Larix gmelinii> Betulla platyphylla.In the four forest types, soil microbial AWCD value in the surface soil layer was decreased after chlorothalonil was sprayed in 0Month-2Months; soil microbial AWCD value in the 0-20cm soil layer was decreased after chlorothalonil was sprayed in OMonth. Soil microbial AWCD value in the surface soil layer was decreased after fenvalerate was sprayed in OMonth.(2) Influence of pesticides on soil microbial diversity indexIn the check soil sample, for all the forest types, the trend of Shannon-Winner diversity index in time was 10Months>OMonth>2Months>6Months, in space was surface soil layer >0-20cm layer, in different forest types was Tilia amurensis> Abies nephrolepis> Larix gmelinii> Betulla platyphylla. The trend of Simpson diversity index in time was 10Months> 6Months> OMonth>2Months, in space was surface soil layer>0-20cm layer, in different forest types was Tilia amurensis> Abies nephrolepis> Betulla platyphylla>Larix gmelinii. The trend of Mclntosh diversity index in space was surface soil layer>0-20cm layer. In time, Abies nephrolepis fotest was 10Months>6Months>OMonth>2Months, Tilia amurensis and Betulla platyphylla fores were 10Months>2Months>6Months>0Months, Larix gmelinii forest was 10Months>6Months>2Months>OMonth. In different forest types was Tilia amurensis> Abies nephrolepis> Larix gmelinii> Betulla platyphylla.In the four forest types, both chlorothalonil and fenvalerate could restraint soil microbial Shannon-Winner diversity index, Simpson diversity index and McIntosh diversity index during OMonth-10Months. But the influence effect of two kinds of pesticides was smaller in Korean pine mixed forests.(3) Influence of pesticides on soil microbial carbon source utilization diversityIn the check soil sample, there were 18 kinds of carbon sources in Abies nephrolepis forest,21 kinds of carbon sources in Tilia amurensis forest,11 kinds of carbon sources in Larix gmelinii forest,9 kinds of carbon sources in Betulla platyphylla forest.After sprayed chlorothalonil and fenvalerate, kinds of carbon sources in Abies nephrolepis forest was respectively reduced to 11 and 13, kinds of carbon sources in Tilia amurensis forest was respectively reduced to 15 and 17, kinds of carbon sources in Larix gmelinii forest was respectively reduced to 3 and 6, kinds of carbon sources in Betulla platyphylla forest was respectively reduced to 9 and 4.5、Residues and degradation of two kinds of pesticide in different forest typesIn the four forest types and all soil layers, the trend of chlorothalonil residual concentration in OMonth was Larix gmelinii>Betulla platyphylla> Abies nephrolepis>Tilia amurensis.In the four forest types, the surface soil layer trend of fenvalerate residual concentration in OMonth was Betulla platyphylla>Larix gmelinii> Abies nephrolepis> Tilia amurensis, the 0-20cm soil layer trend of fenvalerate residual concentration in OMonth was Beiulla platyphylla >Larix gmelinii>Tilia amurensis>Abies nephrolepis. The degradation rate of chlorothalonil and fenvalerate in Abies nephrolepis and Tilia amurensis fotest were faster than in Larix gmelinii and Betulla platyphylla fotest.6、Soil microbial communities functional diversity changed with pesticides degradation in the soilIn Abies nephrolepis fotest, the soil microbial carbon metabolic functional commutity activity which mainly take carbohydrates, carboxylicacids, amino acids, polymers as carbon sources were restrainted by chlorothalonil in 0Month-2Months, but promotes the phenolic utilization of soil microbial carbon metabolic functional commutity in 6Months-10Months. The soil microbial carbon metabolic functional commutity activity which mainly takes carboxylicacids, amino acids, amine as carbon sources were restrainted by fenvalerate in 0Month-2Months, but promotes the phenolic and polymers utilization of soil microbial carbon metabolic functional commutity in 6Months-10Months.In Tilia amurensis fotest, the soil microbial carbon metabolic functional commutity activity which mainly take carbohydrates, carboxylicacids, amino acids as carbon sources were restrainted by chlorothalonil in 0Month-2Months, but promotes the phenolic and polymers utilization of soil microbial carbon metabolic functional commutity in 6Months-10Months. The soil microbial carbon metabolic functional commutity activity which mainly takes carboxylicacids and amino acids as carbon sources were restrainted by fenvalerate in OMonth, but promotes the polymers utilization in 6Months-10Months.In Larix gmelinii fotest, the soil microbial carbon metabolic functional commutity activity which mainly take carbohydrates, carboxylicacids, amines, phenolic as carbon sources were restrainted by chlorothalonil in 0Month-2Months, but promotes the polymers utilization of soil microbial carbon metabolic functional commutity in 6Months-10Months. The soil microbial carbon metabolic functional commutity activity which mainly takes carboxylicacids and amino acids as carbon sources were restrainted by fenvalerate in 0Month-6Months, but promotes the polymers utilization in 10Months.In Betulla platyphylla fotest, the soil microbial carbon metabolic functional commutity activity which mainly take carbohydrates, amino acids, amines, polymers as carbon sources were restrainted by chlorothalonil in 0Month, but promote the carboxylicacids and polymers utilization of soil microbial carbon metabolic functional commutity in lOMonths. The soil microbial carbon metabolic functional commutity activity which mainly takes carboxylicacids as carbon source was restrainted by fenvalerate in OMonth-lOMonths, but promotes the phenolic and polymers utilization in 6Months-10Months. |
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