Changes of grass root system, soil fauna and soil microflora in the process of decaying of crushed wood fragments.

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The author investigated the change of grass root system, soil fauna and soil microflora in the ploughless pasture soil rich in crushed wood fragments in a mountainous region in Aomori Prefecture. The results obtained are as follows.1. Though the numbers of Collembola and Acari decreased from 10^*4/m^2 to 10^*3/m^2 in the establishment, they increased again 3 months after the establishment. The proportion of Acari increased from 20% to 50% in the surface layer after the establishment.2. The numbers of bacteria, actinomycetes and fungi were 10^*6, 10^*6 and 10^*4/g of dried soil respectively before the establishment. They increased 10times after the establishment. The numbers of them in the much wood test plot were less than those in the less wood plot.3. The numbers of bacteria and actinomycetes, fungi and cellulose decomposing microbe were 10^*7 -8, 10^*5 -6, and 10^*6 -7/g of dried soil respectively. They increased from May to October gradually. The numbers of cellulose decomposing microbe in the test plot were more than those without crushed wood fragments.4. Cellulose papers buried in the surface soil were almost decomposed in 50-60 days either in the test field or in the laboratory regulated temperature and humidity. The decomposing rate increased two times, 20-30 and 40 -50 days. Though the numbers of bacteria, actinomycetes, fungi and microbial biomass C increased in both 2 times, those of cellulose decomposing microbe increased only in 20-30 days and decreased in 40 -50 days.5. The numbers of Acari, Collembola and Nematoda were 10^*4 -5, 10^*3 - 5 and 10^*4-7 /m^2 respectively and those of Acari and Nematoda increased gradually from spring to autumn. Though Nematoda were observed in every layer, Acari and Collembola were observed only in the surface layer. The ecological type of the Nematoda observed were classified to live by the fresh water and in wet soils.