| Although the virgin forest of the Patio gorge, Fox Mountain(located in Xigoucountryside, Minhe county, Qinghai province) had a high covered vegetation and richbiodiversity, the soil ecosystem health assessment had not been done yet.Thus, thepaper studied the dynamic changes of microbe number, enzyme activity andphysicochemical properties in soils sampling at different places, and different depthsduring the seasonal alternating period, that is, May, August, and November,2013.Theselection of the sampling site was based on the different environmental factors, suchas elevation, slope, aspect, vegetation types, and so on.The aim of this study was tounderstand their seasonal variation and effects on the soil fertility, revealed the healthcondition of soil ecological system, and provided a scientific basis for the securitymaintenance of the forest ecological system.The results showed that:(1) The average pH value in the six sampling sites was fluctuated from6.5to7.5during the seasonal changes.The soil electrical conductivity (EC) and the moisturecontent decreased as the depth increased, while the soil bulk density showed anopposite trend. The EC value was high in summer and low in winter, while the soilmoisture and the soil bulk density was much higher in summer and winter. Forexample, the content of TOC, available phosphorus and nitrate of the5#sample wasthe hightest in August, but the content of available potassium decreased directly as thetime gone.The content of available potassium and nitrate1of the1#sample decreasedwith a concave trend, while those of the2#sample was nearly a linear decrement.(2) The numbers of the three soil microbes decreased with depths and had asignificant difference between each other.Meanwhile, the maximum number wasbacteria, followed by actinomycete, and fungi.The number of soil microbes was mostin August,357.25×106/(g·dry soil), and then was November,84.29×106/(g·dry soil),the least was in May,76.68×106/(g·dry soil).The soil respiration intensity wasdifferent from the sampling sites.The maximum was7.19CO2mg/(g soil·24h) in the5#sample. The soil respiration intensity changed with the seasonal variation in all6sampling sites, and the maximum was in August. (3) The activitives of cellulase, urease, phosphatase and catalase decreased withdepth increasing in all six sites.The seasonal change of urease activity showedconcave in all six sites, and the minimum value was in August, while that ofphosphatase activity was a convex with the maximum in August.Those of cellulaseand phosphatase activity were both convex in the5#and6#sample with themaximum in August.As for the1#,3#and5#sites, the activity of catalase declinedwith the seasonal change.The seasonal change of1#was the maximum in November,which of4#was parabolic, and the rest was concave with the minimum in August.Inshort, the seasonal change of soil enzyme activity varied greatly among the samplesites, especially catalase activity.(4) Fungi had a significant positive correlation with four enzyme activity.Eg，bacteria and actinomycetes had a significant positive correlation with phosphataseactivity, meanwhile,bacteria had significant positive correlation with and cellulaseactivity,what was more,there was a positive correlation among three categories of soilmicroorganisms, soil respiration, moisture content and nitrate, but they had negativelycorrelated with soil bulk density; in addition, all four activity were significantlypositively correlated with moisture content, while they had negative correlation withsoil bulk density.In short, there were mutual contact and mutual influence amongmicrobial, physicochemical property and enzyme activity. |
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