区域桉林土壤质量特征的综合分析

通过对广东茂名小良水土保持试验站的天然混交林、阔叶林、松桉混交林、光板地和不同品种的纯桉林共9块试验地的45个观测点土壤的物理性状、化学性状、微生物性状和酶活性共32个影响土壤质量的指标进行取土化验测试、方差分析和系统聚类分析，结果表明：当λ=20时，分2类：1、2号样地为一类;其它样地为一类；当λ=10时，分3类：4号样地为一类；1、2号样地为一类；其它的（3、5、6、7、8、9）样地为一类；当X=5．1时，分5类：4号样地为一类；1、2号样地各分为一类；5、6、7号样地为一类；3、8、9号样地为一类．可见此种分类中各类土壤质量的特征非常明显，地力好、差顺序与实际样地完全相符．方差分析发现：9块样地之间的物理性状差异极显著（P0.01〉value）；酶活性方面的差异较显著；各项化学和微生物性状的差异远远小于物理的差异．通过分析看出，小良各样地的土壤性状相差不大，相对均一，并且土壤质量各方面的性状特征都很差．可见，土壤生态修复是一个非常缓慢的过程，要迅速控制水土流失，改善土壤质量，必须辅以人工措施，以加速生态修复的进程．

Variance Analysis and Hierarchical Cluster Analysis on Characteristics of Soil Quality in Region

This paper reports on the studies of soil samples from the region of Xiaoliang water conserva- tion station, in Maoming, Guangdong, and its naturally restored forest, including naturally restored for- est, broad leaf forest, eucalyptus pine mixed forest and bare land etc. 32 indices based on the physical, chemical, microbiological and enzyme properties of the soil are studied, from 9 different vegetation pat- terns at 45 observation points through soil tests, variance analysis and hierarchical cluster analysis. The re- sults show that, when λ = 20, there are two categories, sample field 1 and 2 classify as one category, and the others classify as one; when λ =10, there are three categories： sample field 4 is one category, sample field 1 and 2 classify as the other category, and all the others （3,5,6,7,8,9） classify as the third category; wherul =5.1, there are five categories： sample field 4 is one category, sample field 1 and 2 separately clas- sifies as one each, sample field 5,6 and 7 classify as one, and 3,8 and 9 classify as one. It is seen that the classifications of sample soil quality are perfectly clear, and the results of sample soil productivity are in good agreement with the real field situations. Through the variance analysis, it is shown that the physical characteristics of the 9 sample fields have significant differences（ P 0.01〉value）. the enzyme properties show relatively significant differences too; and the differences in chemical and microbiological characteris- tics are much less than those of physical characteristics. Through the analysis, it is shown the soil quality in each sample field shows relatively uniform characteristics, which are quite poor. In conclusion, the eco- logical restoration of soil is a very slow process. In order to control the water and soil erosion, improve the soil quality, manual actions must be carried on in the ecological restoration process.