中亚热带典型人工林土壤质量演变及其环境意义

Soil quality evolvement and its environmental significance of typical plantations in mid-subtropics of China

对中亚热带不同发育阶段的杉木(Cuninghamia lanceolgta)和湿地松(Pinus elliottii)人工林以及对照次生常绿阔叶林土壤的有机质、全氮、全磷和碱解氮、速效磷和速效钾含量进行了研究。结果表明:从不同森林类型来看,土壤有机质、全氮和全磷表现为次生林高于杉木和湿地松林,且杉木随着林龄增加而增加,湿地松随林龄增加而降低,但土壤全磷相对前二者变化较平缓;土壤速效态养分总体也表现为次生林高于杉木和湿地松林,但10年生和20年生杉木林土壤碱解氮和速效钾含量低于30年生杉木林的土壤,而湿地松林土壤则相反;另外,从生态环境角度探讨了肥力指标演变可能带来的生态环境影响,提出适当延长杉木人工林轮伐期和缩短湿地松人工林轮伐期对土壤肥力和有机碳库功能保持具有现实意义。

Taking the Cuninghamia lanceolata and Pinus eUiottii plantations at different development stages in the mid-subtropics of China as test objects, and with the secondary evergreen broadleaved forest as the control, their soil organic matter, total nitrogen and ph6sphorus, and available nitrogen, phosphorus, and potassium contents were analyzed. Comparing with secondary evergreen broadleaved forest, the C. lanceolata and P. elliottii plantations had lower contents of soil organic matter and total nitrogen and phosphorus. These contents increased with increasing age of C. lanceolata but decreased with increasing age of P. elliottii, and the changes in soil total phosphorus content were more smoothly than those in soil organic matter and total nitrogen con- tents. Soil available nutrient contents showed the same variation trends, but the soil available nitrogen and potassium contents were lower in 10 and 20 year-old than in 30 year-old C. lanceolata while in adverse for P. elliottii. From the viewpoint of the eco-environmental effects of soil quality evolvement, to properly prolong the rotation period of C. lanceolata and shorten the rotation period of P. elliottii would be of practical significance in maintaining soil fertility and soil organic carbon sink.