黄河三角洲不同林龄柽柳人工林土壤养分及生物学特性研究

Soil nutrients and biological characteristics of Tamarix chinensis plantations with different ages in the Yellow River Delta

以黄河三角洲为例,对3种不同林龄(8a、6a、3a)柽柳人工林进行研究,采用野外调查采样和室内分析相结合的方法,探讨了不同林龄柽柳人工林土壤养分、微生物数量及酶活性的变化特征及其相互关系。结果表明:土壤pH值随着林龄的增加呈降低趋势,随土层深度的增加呈升高趋势。8a的土壤有机质和养分含量显著高于3a林地(P<0.05)。土壤微生物数量及酶活性均随林龄的增加而增加,其中微生物数量中以细菌数量最多,放线菌次之,真菌最少,8a林地的微生物数量、土壤过氧化氢酶、磷酸酶及蔗糖酶活性均显著高于3a林地(P<0.05),8a林地的土壤脲酶活性显著高于6a和3a(P<0.05)。从土壤剖面看,土壤养分含量、微生物数量及酶活性均随土层深度的増加而递减,且表层土的各指标与深层土差异显著(P<0.05)。相关分析表明,土壤微生物数量及酶活性均与土壤pH值呈负相关,微生物中除真菌数量与有机质、铵态氮、有效磷、速效钾养分指标未达到显著相关外,其它均与土壤有机质、养分达到显著正相关。土壤磷酸酶与有机质呈显著正相关,其它3种土壤酶活性与土壤各养分含量之间均达到极显著正相关。

By the methods of field investigation and laboratory analysis, we studied the change characteristics and correlations of soil nutrient, microbial biomass and enzyme activity of Tamarix chinensis plantations with dif- ferent ages （8a, 6a and 3a） in Yellow River delta. The results indicated that the soil pH values were decreased with the increasing of stand ages, and increased with the increase of soil depth. The contents of soil organic matter, ammonium N, nitrate N, available P and available K in 8 -year- old plantations were significantly higher than those in 3 - year - old plantations （ P 〈 0.05 ）. Soil microbial biomass and enzyme activity were increased the increasing of stand ages, and the soil microbial biomass decreased in the order of bacteria 〉 actinomycete 〉 fungi. In addition, the soil microbial biomass and the activities of soil catalase, phosphatase and invertase in 8 - year - old plantations were significantly higher than those in 3 - year - old plantations （ P 〈 0.05 ） , while the soil urease activities in 8 - year - old plantations were remarkably higher than those in the other aged plantations （ P 〈 0.05 ）. Moreover, the soil nutrient content, microbial biomass and enzyme activity were decreased with in- creasing soil depth, and there were significant differences in all the indexes between surface and deep soil （ P 〈 0.05 ）. Furthermore, soil microbial biomass and enzyme activity were negatively related to soil pH values. Ex- cept the fungi, which did not show significant correlation with organic matter, ammonia nitrogen, available p, available k nutrient indices, other microorganism showed significant positive correlation with the soil nutrient. The soil phosphatase activities were positively correlated with soil organic matter content, and soil nutrient contents were positively related to the activities of soil catalase, catalase and invertase.