不同间伐处理对马尾松人工林土壤特性季节动态变化的影响

Seasonal Dynamic Response of Soil Characteristic of Pinus massoniana Plantation to Different Thinning Treatments

通过对马尾松人工林进行不同强度的间伐处理,探讨间伐处理4 a后土壤酶活性、土壤碳氮质量分数、微生物数量的季节变化模式。结果表明:相对未间伐处理(T_(0)),轻度间伐(T_(1))对碱解氮质量分数及硝化细菌数量、中度间伐(T_(2))对氨化细菌及硝化细菌数量的影响受季节变化调控,2种间伐处理在各季节中对其余土壤特性均表现出稳定促进作用,但促进效应无明显的季节规律。重度间伐(T_(3))仅对土壤全氮质量分数、放线菌及真菌数量具有稳定促进作用,该处理持续不显著抑制过氧化氢酶活性,对其余土壤指标的影响存在季节性差异,但无明显规律。主成分分析显示,间伐能提高林地质量,不同处理下土壤质量由优到差依次为:T_(2)处理、T_(1)处理、T_(3)处理、T_(0)处理。对马尾松人工林进行适度间伐作业可以提高林地土壤质量,而中度间伐是3种间伐强度中的最优选择。间伐对部分土壤特性的影响因季节而异,土壤因子的季节变化是准确判断间伐措施对土壤质量影响的重要考量。

With different thinning intensities on a Pinus massoniana plantation, the seasonal dynamics of soil enzyme activity, the contents of soil carbon and nitrogen, and microbial population were studied after thinning for four years. The result showed that available nitrogen and nitrobacteria population changed with seasonal variation under mild thinning (T_(1)), and ammonifying bacteria population and nitrobacteria population changed with seasonal variation under moderate thinning (T_(2)) compared to no thinning treatment (T_(0)). These two thinning intensities had stable promotions on the rest indexes of soil characteristics in each season, but the promotion had no rules with seasonal variation. Severe thinning (T_(3)) only showed stable promotion on mass fraction of total nitrogen, actinomycetes population and fungi population, and T_(3) treatment restrained catalase activity continuously but not significantly. The effects of T_(3) on the rest indexes of soil changed with seasonal variation, but without obvious rules. The principal component analysis revealed stand quality was improved by thinning, the soil quality was ranked in descending order of T_(2), T_(1), T_(3) and T_(0). Appropriate thinning can improve soil quality of P. massoniana plantation, and moderate thinning is the best choice among the three thinning intensities. At the same time, the effect of thinning on soil characteristics may vary from season to season, and seasonal changes in soil factors are important considerations for accurately judging the impact of thinning treatments on soil quality.