Spatial Heterogeneity Of Soil Enzyme Activities In Typical Catchment Area Of Karst In Guizhou Province

Spatial heterogeneity is a major attribute of soil ecosystem,and it is also the main cause of spatial pattern.Many studies have found that the spatial distribution pattern of species has a great relationship with spatial heterogeneity in soil.Soil enzyme activities are sensitive biological indicators of soil quality,while their spatial heterogeneity and influencing factors are not well understood.In this study,geostatistics,Kriging,one-way ANOVA and correlation analyses were used to study the spatial variability and influencing factors of 0-10 and10-30 cmβ-1,4-glucosidase（βG）,β-1,4-xylosidase（βX）,cellobiohydrolase（CBH）,β-1,4-N-acetylglucosaminidase（NAG）,leucine amino peptidase（LAP）,acid phosphatase（AP）,Phenol oxidase（PPO）and Peroxidase（PER）in a karst catchment in Guizhou,China.1.The activity of 8 types of soil enzyme in the soil surface（0¹0 cm）is between 45⁹91nmol·g-1·h-1,and the order is AP>LAP>CBH>NAG>βG>βX>PPO>PER.The enzyme activity of the subsurface soil（10³0 cm）is between 37⁹29 nmol·g-1·h-1,and the order is AP>LAP>βG>CBH>NAG>βX>PPO>PER.With the increase of soil depth,soil enzyme activity decreased.AP activity was highest at all levels of soil.The soil enzyme activity decreases with the increase of soil depth and AP activity is highest at all layers of soil.2.The variation range of soil enzyme activity varies from 24.42%to 72.2%.Every soil enzyme activity is medium variation in surface and subsurface.The variation coefficient of LAP and AP activities in subsurface soil are 58.8%and 72.2%,more than 53.2%and 46.5%in the surface.The other enzymes are characterized less in subsurface than surface and they were respectively NAG 45.2%>31.9%,βG 38.7%>37.9%,βX 56.9%>43.1%and CBH48.7%>43.8%.The variation coefficient of PPO activity in the surface is 26.04%greater than25.69%in the subsurface,and the variation coefficient of PER activity in the subsurface soil is42.45%greater than 24.42%in the surface.The enzyme activity in soil surface is easier to be mutated with the influence of random factors.3.The range of all kinds of soil enzyme（βG,βX,CBH,NAG,LAP,AP,PPO and PER）activity in this study are differences,they are 31.4m,48.3m,42.1m,122.8m,27.3m,96.2m,68.1m,43.9m in the deep layer,and 33.7m,333.4m,187.1m,25.5m,401.1m,184.6m,187.1m,232.1m in the surface layer.In addition to NAG,surface soil enzyme activity（122.8m）is larger than the lower layer（25.5m）.It can be seen that the sampling interval distance determined according to the surface variation of the enzyme activity surface also conforms to the requirements of soil sampling in the lower layer.4.Soil enzyme activity has a certain degree of spatial autocorrelation,the structure of the variance ratio C/（C₀+C）of soil enzymes（except subsurface soil PPO）activities of all layers are between 50.0%⁹9.9%respectively,and they are showing a strong or moderate spatial correlation.5.There are obvious heterogeneity patches of soil enzyme activity,and there is a certain degree of consistency between the enzyme activity of the same function.Soil NAG and LAP activity are positively correlated with SWC and NH₄⁺-N;NAG and AP are positively correlated with NO₃^--N;In addition to NAG,the activity of other soil hydrolytic enzymes is significantly correlated with pH.Among them,there is significant positive correlation forβG,βX,CBH and LAP,and the AP is significantly negatively correlated with pH.6.The effects of land use types forβG、βX、CBH、LAP and PER are not significant,while the differences of activity between AP,NAG and PPO in different land use types are significant.The activity of AP and PPO is significantly higher in farmland than in secondary forest and abandoned cultivated land,and there is no significant difference between secondary forest and abandoned cultivated land.The activity of NAG in secondary forest is significantly higher than that of abandoned cultivated land and farmland.There is no significant effect on the activity of eight kinds of soil enzymes（βG、βX、CBH、NAG、LAP、AP、PPO and PER）in the slope aspect（northeast slope and southwest slope）.There is no significant effect of slope position on the activity ofβG、βX、CBH、NAG、LAP and PER,and significant influence on the activity of AP and PPO（P<0.05）.The activity of AP in the lower slope(1267 nmol·g^-1·h^-1)is significantly higher than that in the upper slope(887 nmol·g^-1·h^-1)and middle slope(836nmol·g^-1·h^-1).Similarly,the activity of PPO in the lower slope(67 nmol·g^-1·h^-1)is significantly higher than that in the upper slope(53 nmol·g^-1·h^-1)and middle slope(56 nmol·g^-1·h^-1)...