东江流域阔叶混交幼林林地土壤养分变化分析

对枫香 樟树、楠木 尖叶杜英、椆木 海南红豆、格木 海南红豆、火力楠 阴香、樟树 马占相思、枫香 米者排 降香黄檀等阔叶混交幼林林地的土壤养分变化进行了分析。结果表明：造林2年后不同混交林地的pH值均有所下降，而土壤的有机质、全N、有效N和有效P含量呈现增长趋势；全P、全K和有效K含量在一些混交林地增加，在另一些混交林地下降。大多数混交林对P和K的需求量大，造成土壤全P和K含量的减少，需要施P肥和K肥以促进林木生长。有机质与全N、有效N、有效P，全N与有效N，全K与有效K均相关极显著。

ANALYSIS ON THE SOIL NUTRIENTS VARIATION IN MIXED BROADLEAVED STANDS

The Changes of soil nutrients were studied in stands of Liquidambar formosana+Cinnamomum camphora, Phoebe nanma+Elaeocarpus apiculatus, Lithocarpus thalassica+Ormosia pinnata, Erythrophloeum fordii+Ormosia pinnata, Michelia macclurei+Cinnammomum burmanii, Cinnamomum camphora+Acacia mangium and Liquidambar formosana+Mytilaria laosensis+Dalbergia odorifera . The results show that pH decreased in soils of different mixed stands. Soil organic matter, total N, effective N and effective P tended to increase, whereas total P total K and effective K increased in the soils of some mixed stands and decreased in the soils of others. Demand amounts of P and K were great for most mixed stands, resulting in decrease in amounts of total P and K, so that P fertilizer and K fertilizer were need to accelerate tree growth. There was a close correlation between soil organic matter and total N, and effective N as well as effective P, this correlation was also existed between total N and effective N and between total K and effective K.