| 1. | Mongolica young stand , secondary natural forest , and the mixed forest of larix olgensis and fraxinus mandshurica rupr . . countermeasures for controlling soil degradation were also recommended . the study got following results : ( 1 ) from young stand to mid - age of larix olgensis , with the closure of canopy and the decrease of undergrowth vegetation cover , soil acidity , enzyme activity , total inorganic phosphorus , available k , soil moisture and total porosity decreased significantly ; while soil organic matter content , humus component content , the amount of three main types of microbes , acid phosphatase activity , and bulk density in rhizosphere soil and non - rhizosphere soil increased with the increase of the amount of forest floor litter ; from mid - age stand to near mature stand , with the decrease of stand density and crown cover as well as the restoration of undergrowth vegetation after preliminary thinning , soil organic matter content , fulvic acid , exchangeable acidity , exchangeable aluminium , neutral phosphatase activity , total amount of inorganic phosphorus , the amount of actinomycetes , soil moisture , and total porosity in rhizosphere soil and non - rhizosphere soil apparently increased ; from near matu re stand to mature stand , soil activity acidity , organic matter content , humus component content , available phosphorus , total amount of amino acid , available k , soil enzyme activity , soil moisture , and total porosity in rhizosphere soil and non - rhizosphere soil decreased , but total phosphorus , soil acidity ( in particular , exchangeable aluminium ) , and bulk density increased
结果表明： ( 1 )从落叶松幼龄林到中龄林，随着林冠的郁闭和林下植被盖度的急剧下降，林地土壤酸度、土壤酶活性、无机磷总量、速效钾、土壤水分含量、总孔隙度呈明显下降趋势，而根际和非根际土壤有机质含量、腐殖质各组分含量、三大类微生物数量、酸性磷酸酶活性和土壤容重随着凋落物的增加呈明显上升趋势；从中龄林到近熟林，由于抚育间伐，林分密度及郁闭度下降，林下植被盖度逐步得到恢复，根际与非根际土壤有机质含量、富里酸、交换性酸、交换性铝、中性磷酸酶、无机磷总量、放线菌数量、土壤水分含量、总孔隙度呈明显的上升趋势；从近熟林到成熟林，随着林龄的增大，根际与非根际土壤活性酸、有机质含量、腐殖质各组分含量、有效磷含量、氨基酸总量、速效钾、土壤酶的活性、土壤水分含量和总孔隙度呈下降趋势，而根际与非根际土壤全磷含量、土壤酸度(特别是交换性铝)和容重呈增加趋势。 |
