| Phyllostachys violascens is one of eximious monopodial bamboo species.The technique of covering had been used on bamboo planting in Lin, an, Zhejiang province which made bamboo shoot as a kind of anti-season vegetables and made farmer rich.However the yield of bamboo shoots decreased obviously after covering many years.It was necessary to find out the reason to bamboo degeneration before solving the problem.The paper studied on the soil changes to bamboo growth and tried to find the solutions to bamboo degeneration by determining the soil properties of Phyllostachys violascens.The covering bamboo stand covered in mid Dec. 2007. Covering materials were removed in late May 2008. The results showed that: the activity of soil enzyme, microbial changed significantly in covering time.The difference between covering and uncovering bamboo stand was decreased after covering materials removed. pH of covering bamboo stand were 4.00 and 4.15 in Jan. and Mar, which were lower than that of uncovering bamboo stand 1.48% and 3.71% respectively. pH of covering bamboo stand was 4.07-4.29 from May to Nov.The pH of covering bamboo stand was increased and was higher than that of uncovering bamboo stand. The to??phenolic acid of covering stand was 32.2976-144.9583 ug·g-1 , which was 1.20-2.97 times higher than that of uncovering bamboo stand, beyond the influence range of tolerance. Activity of Polyphenol oxidase was higher than that of uncovering bamboo stand from Jan. to May. High activity of Polyphenol oxidase would be beneficial to decomposition of phenolic acid. The urease in covering bamboo stand was 1.4240-2.2242mg·g-1h-1, which was 26.36%-48.81% lower than that of uncovering bamboo stand. The decreased activity of urease might have some effects on nitrogen transformation and supply. Catalase activity were 0.121ml·g-1h-1 and 0.2314 ml·g-1h-1, which were lower than that of uncovering forest land 41.00% and 1.70% respectively in Jan. and Mar. Catalase activity decreased which was related to bad aeration situation in covering time. Activity of invertase was 0.5302-0.6749 ml·g-1d-1 , which was higher than that of uncovering bamboo stand in Jan. to May. High activity of invertase was related to increased organic matter and carbon source, which could provide energy for microbial.The total PLFA which represented the biomass of microbial in covering materials were 134.2258 ug·g-1 and 9.9314 ug·g-1, which were 1.65 and 2.84 times higher than that of in covering bamboo stand respectively. The total PLFA in covering bamboo stand were 81.4657 ug·g-1 and 4.0829 ug·g-1 , which were 31.6 and 5.56 times higher than that of in uncovering bamboo stand respectively. G+/G- which represented the relative advantage and range of gram-positive bacteria and gram-nagtive bacteria in covering bamboo stand was higher than that of in uncovering bamboo stand in Jan. and Mar, lower than that of in uncovering bamboo stand in Jul and Nov. Mounounstaturted fatty acid/branched fatty acid which represented the relative advantage of aerobic bacteria and anaerobic bacteria was lower than that of in uncovering bamboo stand in Jan. and Mar, higher than that of in uncovering bamboo stand in Jul and Nov. The cyclopropyl content and cyclopropyl proportion of total fatty acid which represented reducing bacteria and anaerobic environment in covering bamboo stand were higher than that of in uncovering bamboo stand in one year. When covering in Janury and March, the biomass of microbial increased significantly, especially the biomass of bacteria, then the biomass of fungi. The reducing bacteria and anaerobic bacteria increased. Soil aeration situation was worsening. The soil aeration situation improved in July and November by removing of covering materials and ploughing. The difference between covering and uncovering bamboo stand would be decreased.In su??y, phenolic acid increased, the biomass of microbial increased significantly, the reducing bacteria and anaerobic bacteria increased significantly. Microbial consumed lots of oxygen and produced metabolites. Catalase activity decreased indicate bad aeration situation in covering time. The decreased activity of urease might have some effects on nitrogen transformation and supply.Removing covering materials would improve the aeration situation and would be beneficial to bamboo growth.
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