不同密度巨桉林草复合模式初期土壤特征研究

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

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。

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 cornpressa （L. f） R. BY. ] is more appropriate for the district.