Quality Evaluation of Soil Fertility of 13-year-old Cunninghamia lanceolata Plantations with Different Site Factors
The soil fertility quality of Cunninghamia lanceolata plantations under different site factors was studied,which provided a theoretical basis for the fine management of C.lanceolata plantations.Soil fertility quality of 21 plots of C.lanceolata plantations with different site factors was comprehensively evaluated by membership function and principal component analysis method,and the cluster analysis was used to classify and grade.The results showed that the soil nutrient content of the 21 plots conformed to the normal distribution,and the coefficients of variation were as follows:total phosphorus(24.22%)>organic matter(20.25%)>alkaline hydrolyzable nitrogen(20.02%)>available phosphorus(18.06%)>total potassium(16.79%)>total nitrogen(16.24%),but the soil nutrient coefficient of the same soil varies greatly.The comprehensive fertility index(SI)of 21 plots ranged from 18.44%to 86.23%,and the SI of plot No.10 was the largest,which belonged to Class I.There were 10 plots in 11,16,12,9,14,1,21,19,8,18(47.62%),with SI ranges of 53.12%to 72.04%,which belonged to Class II.There were 7 plots in 17,20,5,15,2,7 and 13(accounting for 33.33%),with SI variation ranging from 36.71%to 48.79%,which were generally suitable for Class III.There were three plots in No.6,4 and 3(14.29%),with SI ranges of 18.44%to 27.83%,which belonged to Class IV unsuitable.The suitable and more suitable plots are basically between the north slope and the east slope.In summary,the comprehensive evaluation method and cluster analysis can be used to evaluate the soil fertility quality of C.lanceolata plantations,and the forest land from the north slope to the east slope is more suitable for the growth of C.lanceolata than the western slope and the southern slope.C.lanceolata plantations have high demand for nitrogen and phosphorus.
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