The Decomposition of Juncus Squarrosus Leaves and Microbiological Changes in the Profile of Juncus Moor

Abstract

1. The decomposition of Juncus squarrosus leaves and the microbiology and chemistry of the leaves and profile were studied on a Juncus moor at the Moor House National Nature Reserve, Westmorland, England. 2. Leaves in nylon nets remained in the L layer for about 1 year and in F1 for at least 15 months. During this period they lost 20-30% dry weight/year. Chemical differences in different parts of the leaves remained during the 21/2 years decomposition, the loss of chemical components being similar to that recorded in other studies. 3. The amount of stained (46-92 m/cm3) and unstained (98-148 m/cm3) fungal mycelium was greatest in the F and H1 horizons and decreased in the H2 and H3. The percentage of stained mycelium, of particles colonized and of fast-growing fungi all decreased down the profile. A spring peak in the amount of hypae was shown in all horizons. 4. Bacteria showed vertical and seasonal patterns similar to those of the fungi. The range of numbers in the F was 33-39 × 108/cm3 in direct and 3-7 × 105/cm3 in dilution counts. Small rods constituted 63-94% of the numbers in direct counts and decreased with depth. Respiration was also highest in the upper horizons $(< 10 \mu l O_2/cm^3/h)$. 5. Dark fungi, many of them sterile, predominated in all horizons. On the fresh litter Stagonospora, Dinemasporium graminum, Dasyscypha diminuta and Mollisia palustris were common. These were replaced on older litter by the common soil Hyphomycetes (Trichoderma, Penicillium and Mortierella). In the lower parts of the profile SD-9 and sterile white fungi predominated. 6. The biomass of microflora is estimated as between 28 and 197 g wet weight/m2. This constitutes one-half to two-thirds of the total biomass of fauna and microflora.