落叶松水曲柳纯林与混交林根际土壤中养分浓度的变化

在落叶松水曲柳纯林与混交林中,采集林地土和根际土,测定了氮、磷、钾浓度,目的是探讨养分条件变化在混交林增产上的作用。结果表明:混交林林地土全氮浓度和水解氮浓度与水曲柳纯林相近,但要高于落叶松纯林。水曲柳在混交林中根际土全氮和水解氮浓度与纯林中的相近,而落叶松在混交林中根际土水解氮浓度明显高于纯林中的。混交林林地土全磷和全钾浓度与两个树种的纯林相差不大。混交林林地土有效磷、有效钾浓度均高于水曲柳纯林,而且水曲柳在混交林中根际土的有效磷和有效钾浓度与纯林中的相比明显增加,分别高出44.1%~79.6%和13.5%~25.6%。这说明水曲柳在混交林中磷和钾的利用状况得到了改善。表2参15。

The variation of nutrient concentration in the rhizosphere of larch and ash in mixed and monoculture stands

Soil samples were taken from rhizosphere zone and off-rhizosphere zone of ash (Fraxinus mandshurica Rupr.) and larch (Larix olgensis Henry) in mixed and monoculture stands, and the nutrient concentration of N, P, and K was analyzed to study the effect of nutrients variation on yield improvement in the mixed stand. The result showed that: 1) The stand level total soil N concentration and available N in the mixed stand was similar to that in the monoculture stand of ash, but higher than that in monoculture stand of larch. The total N and available N concentration in rhizosphere soil of ash in the mixed stand was similar to that in the monoculture stand of ash, but the available N concentration in rhizosphere of larch in mixed stand was much higher than in its monoculture. 2) The stand level total P, total K concentration in the mixed stand was similar to that in monocul-ture stands of both species, but available P and K was more concentrated in the mixed stand than in the monoculture stands of ash. The rhizosphere available P and K of ash in the mixed stand was 44.1% and 13.5% (for the 9-yr-old stands) and 79.6% and 25.6% (for the 21-yr-old stands) higher than that in its monoculture. The improvement of soil P and K availability in the mixed stand is concluded.