不同密度巨桉林草复合模式初期土壤特征研究

在株距为1.5 m,行距分别为3、4、5、6、8 m,相应初植密度为2222、1667、1333、1111、833株/hm25种不同密度的巨桉林中,设置3种巨桉林草复合种植模式:巨桉+鸭茅(简称模式Ⅰ)、巨桉+高羊茅(模式Ⅱ)、巨桉+牛鞭草(模式Ⅲ)。对该复合模式土壤特征进行了定位研究。初期结果显示:土壤物理性质(容重、非毛管孔隙度与总孔隙度)均有一定程度的改善;土壤有机质变化3种模式大体一致,表现为5月>11月>8月,水解氮动态变化则表现为8月>5月>11月,而有效P与速效K均表现为5月>8月>11月;方差分析表明,3种模式间土壤各速效养分变化差异均达到显著水平(P<0.05),但由于处于林草复合模式初期,不同密度间变化差异尚不太明显。综合土壤养分动态变化与已有相关研究结果,初步认为模式Ⅲ(巨桉+牛鞭草模式)为该地比较适宜的种植模式。

Studies on Soil Characteristics of Different Stand Densities of Eucalyptus grandis+grass Compound Patterns at Initial Stage

The experiment was conducted in three Eucalyptus grandis+grass compound planting patterns which have five different densities.Three patterns were E.grandis+Dactylis glomerata L.(pattern Ⅰ),E.grandis+Festuca arundinacea Schreb.(pattern Ⅱ),E.grandis+Hemarthria compressa(L.f) R.BY.(pattern Ⅲ).Soil characteristics of the compound planting patterns were studied.The primary results showed as follows: The soil physical properties(bulk density,non-capillary porosity and the total porosity) were improved to a certain degree.The account of soil organic matter had comparable trends among the three patterns and the order of the account of soil organic matter was May>November>August.The order of hydrolysis nitrogen was Augus>May>November.The orders of available P and K were May>August>November.The difference of the soil available nutrients among the three compound planting patterns was significant(P<0.05).The forest densities did not show obvious effect,for the research was carried out at the initial stage of E.grandis+grass compound pattern.Integrating with the soil nutrient dynamics and the related research,the model Ⅲ [E.grandis+Hemarthria compressa(L.f) R.BY.] is more appropriate for the district.