APPLICATION OF A RAPID THIN-SECTION METHOD FOR OBSERVATIONS ON DECOMPOSING LITTER IN MOR HUMUS FORM IN A SUB-ALPINE CONIFEROUS FOREST

Morphological changes in the decomposing litter of Abies spp. and Betu la spp. in a mor humus form were studied by a rapid thin section metho d. According to the morphological characteristics, the epidermis, meso phyll and vascular bundle of Abies needle litter were classified into four types: (i) newly fallen; (ii) slightly decomposed; (iii) moderate ly decomposed; and (iv) greatly decomposed. The distribution of these tissue types along the profile of the forest floor was then investigat ed. The morphological changes in other litter types, such as branches, scales and Betula leaves during decomposition were observed directly with microscope and electron microscope. Five vertical thin sections a nd 80 horizontal thin sections were used for these observations and in vestigations. The decomposition of Abies litter was slower than that o f Betula litter. The relative decomposition rate of the tissues was in the order of mesophyll > vascular bundle > epidermis in Abies needles ; mesophyll greater than or equal to epidermis > vascular bundles in B etula leaves; and inner bark > xylem > outer bark in both Abies and Be tula branches. The last remains of the litter were usually stomata, se gments of seminiferous scale and outer bark of Abies. The decompositio n of plant litter occurred mainly within the L and F layers of the soi l (0-5 cm in depth). Abies needles and Betula leaves completely disapp eared at. depths of 0-6 cm and 0-4 cm, respectively, Branches disappea red within the top of 5 cm and 6-8 cm for Betula and for Abies, respec tively. The scales of Abies were most slowly decomposed in the soil la yers.