Study On Soil Enzyme And Soil Respiration Charcteristics Of Karst Degeneration Vegetation Recovery Procedure

Adopting the concept of space as a substitute for time,we selected four restoration stages relating to bare land,herb,shrub and arbor community as successional series of vegetation restoration in Huajiang degraded Karst region.Respectively we had investigated characteristics of plant community and measured soil physical and chemical properties in this four stages.What's more,enzyme activity of sucrase,urease,amylase,catalase,phosphatase and polyphenoloxidase were determined in three microhabitats relating to soil surface,stone ditch,stone cistern of each restoration stage,and diurnal and seasonal variation of soil respiration was measured in the same site,all of these steps had been done were for revealing the rules of soil enzyme and soil respiration.Finally,we established a quality evaluation system for soil fertility and quality,and assessed the soil quality in each recovery phase. Some key findings are as follows:1.Variations of each soil physical and chemical property had been revealed.Values of water content, soil capacity,soil bulk density,organic matter,total nitrogen,total phosphorus and total potassium in process of plant restoration showed that overall performance in each recovery phase was bare land＜herbal community＜shrub community＜arbor community,each fertility factor value was increasing along with the better vegetation conditions.2.Characteristics of soil enzyme activity had been summarized.Variations of six soil enzymes in process of plant restoration was bare land stage＜herbal community stage＜shrub community stage＜arbor community stage.Distribution of these six enzymes was non-rhizosphere soil＜rhizosphere soil,and B soil layer＜A soil layer on the soil vertical section.Concerning to seasonal dynamics of these six enzymes,generally their activities were higher in summer and autumn,and in winter the lowest; expect for sucrase and amylase,other enzyme activities of summer and autumn in different restoration stages and different soil layers differs,and the value was between spring and winter.Considering the enzyme activity variation in different microhabitats,sucrase and amylase in stone ditch was higher than in soil surface and stone cistern,and activities of other enzymes varied a bit.3.Characteristic of soil respiration was as follows.Change of soil respiration in process of vegetation restoration was bare stage＜herbal community stage＜shrub community stage＜arbor community stage. Soil respiration to the seasonal changes in vegetation restoration of each stage was summer＞spring＞autumn＞winter.Considering the soil respiration variation in different microhabitats. during the former two restoration stages soil respiration in stone ditch was higher than the other two microhabitat kinds,and when going to the shrub and arbor community variation of the soil respiration changed a bit.Considering diurnal variation of soil respiration,the general rules showed a single peak curve,and at 12:00 and 14:00 its value reached its peak point,the lowest point mainly emerged in the 8:00 to 10:00.Relating to temperature and moisture,in different restoration stages correlation between soil respiration and temperature differed,which in herb and shrub community was a bit higher(respectively R~2=0.876,0.9164),and a bit lower in bare land and arbor community(respectively R~2=0.7048,0.733),in forest land and non-forest land correlation between soil respiration and moisture was evident(respectively R~2=0.7329,R~2=0.924).4.An evaluation of soil fertility and quality was made in the end of this chapter.Some indexes relating to soil physical and chemical property of organic matter,water content,soil capacity,soil bulk density, organic matter,total nitrogen,total phosphorus,total potassium,and relating to soil enzyme indexes of sucrase,urease,amylase,catalase,phosphatase,polyphenoloxidase and characteristic of soil respiration were selected.The results reflected that soil quality was increasing along with advancing degree of vegetation succession,and respectively integrated fertility index(IFI)of bare land,herbal community, shrub community,arbor community was 0.005,0.282,0.718,0.994。...