长白山北坡原始林采伐对土壤性质影响的研究

长白山北坡是我国中纬度地区保持得比较完好的著名原始林区。林木组成复杂,成林树种丰富,每公顷蓄积量可达300—600立方米。而适合采伐的成过熟林已占绝大部分。据白河林业局资料:其林分蓄积中成过熟林占90.1%,这些成过熟林的林木生长量已大为减退,平均生长率为3.96%,而自然枯损率却占1.87%。特别是针叶树种平均自然枯损率高达3.79%,几乎与平均生长率相等¹⁾,这表明该局的森林资源应及时开发利用。另一方面,这些可采伐的原始林,地处熔岩高原,是第二松花江的源头,现有森林覆被对于调节气候、涵养水源、保持水土的作用是难于估量的。若采伐方式不当,是否会引起森林立地条件恶化而不利于更新造林,导致生态失去平衡并带来极大的灾难。为此,1982年吉林省林学会联合我院等十多个单位,针对上述问题,从各方面进行考察。笔者等用设立标准地调查对比的方法,于落叶松纯林和阔叶红松林采伐迹地上进行研究,现将初步结果报道如下。

STUDIES ON THE INFLUENCE OF FELLING ON PROPERTIES OF SOILS UNDER PRIMITIVE FORESTS ON NORTH SLOPE OF THE CHANGBAI MOUNTAINS

The area of primitive forests on the north slope of the Changbai Mountains is one of the beat virgin forest regions reserved in northeast China. In order to study the influence of felling of the primRtive forests on the soil properties and its relation to natural reforestation, the field investigation was conducted from June to August in 1982. The main types of forest vegetation in this region are the pure larch forest, the broad-leaved Korean pine forest, the mixed coniferous forest and the mixed broad-leaved forest. gnd under these vegetations the main soils are mountain brown coniferous forest soils, mountain dark brown forest soil and lessive soil. These sail profiles are characterized by the thicker littear layer, higher content of humus and total nitrogen, which decrease rapddly downwards, pH-value ranging from 5.0-6.0, low degree of base saturation, higher content of hydrolytic acid, insignificant illuviation of iron oxide and aluminum oxide, C/N ratio ranging from 15 to 20 and good physical properties. It can be found that felling of the forest results in great changes of soil properties such as the accederated decomposition of litter, the increase of humus and total nitrogen in topsoil, the decrease of soil acidity, and the improvement of physical and moisture properties of the soil, which are favourable for the reforestation. However, clear felling in a too large area will bring about the flourishing growth of the wild grasses and dense development. of their roots in the topsoil, which is unfavourable for the nahural vend artificial reforestation. Therefore, the ra.tionable felling, i.e. selective felling,rather than the clear felling should be adopted, and the intensity of selective felling should be 40-50%. On the clear felling slash, careful preparation of soil before artifical reforestation is necessary, and proper tending of the young growth is of most important for its rapid growth.