闽南山区连续年龄序列桉树人工林土壤养分动态

对闽南山区连续年龄序列(2 a、3 a、4 a、5 a、6 a)的尾巨桉(Eucalyptus urophyllaxE.grandis)人工林土壤有机碳及氮、磷、钾含量进行了分析,以评价土壤养分随林分年龄的变化动态.土壤有机碳、全氮、水解氮、全磷、速效磷均表现出随林分年龄增加而增加,到4 a生时达到最大,随后则呈下降趋势,6 a生时下降到最低值.速效钾含量则随林分年龄增加逐步下降,6 a生林分0～20 cm、20～40 cm和40～60 cm这3个土层速效钾含量分别比2 a生下降了53.2%、44.4%和55.2%;土壤全钾含量也表现出一定的下降趋势.所有年龄林分的土壤有机碳、全氮、水解氮、全磷、速效磷和速效钾含量均随土层深度增加而降低,而土壤伞钾则表现出相反的趋势.因此,在桉树人工林经营过程中,应定期增施钾肥,适时施用有机肥及氮、磷肥,以控制地力衰退.图4表2参24

Soil Nutrient Dynamics in Sequentially Aged Eucalyptus Plantations in Mountainous Region of Southern Fujian, China

The contents of soil organic carbon, nitrogen, phosphorus and potassium in sequencially aged ( 2-, 3-, 4-, 5-, and 6-year old) Eucalyptus urophylla x E. grandis plantations were analyzed in the mountainous region of southern Fujian, China, to estimate the changes in soil nutrients with aging. The soil organic carbon content, total N, hydrolysable N, total P and available P increased with aging and reached maximum at 4 years of age, and thereafter decreased. Soil available K declined significantly with aging. Compared with the 2-year-old stand, soil available K under the 6-year-old stand decreased by 53.2%, 44.4% and 55.2% at the soil depths of 0～20 cm, 20～40 cm and 40～60 cm, respe4ctively. The soil total K also decreased with aging. The soil organic C, total N, hydrolysable N, total P, available P and available K supporting the plantations decreased with soil depth, in contrast the soil total K increased. Therefore, it is needed to apply K fertilizer regularly, and use organic manure, N and P timely in order to control soil degradation in the fast-growing eucalyptus plantation. Fig 4, Tab 2, Ref 24