| Because of the different plantations litter quality and quantity of the leaf, root and canopy structure and other differences will lead to soil environmental characteristics, physical and chemical properties, as well as the different soil biochemical process. Therefore, exploring different methods from the perspective of ecological function pattern characteristics of plantation ecosystem carbon and nitrogen of become very necessary. Global CO2 concentration and temperature, nitrogen deposition and phenological changes and drought stress could cause forest litter input change, therefore, the research on forest soil carbon and nitrogen dynamics in the process of considering the influence of litter input change becomes very important. Therefore, this study in seven slope south Asian tropical of guangxi zhuang autonomous region, the state-owned forest farm topped the forest age the same, similar site conditions, locations, adjacent to three types of plantation (fire nan, pure stand of pinus massoniana and fire nan and pinus massoniana mixed plantation) as the research object, combined with litter input control experiments at the same time, mainly adopts the conventional physical and chemical analysis, process of pneumatic separation technology to PS (Ba) and phospholipids fatty acid (PLFA) soil carbon and nitrogen transformation process of forest on soil and soil microbial community structure analysis, the results are as follows:(1) Three kinds of plantation soil respiration and the total of nitrification rate show significant seasonal variation (p< 0.05), embodied in, soil respiration and total nitrification rate from September 2014 to January 2015 in the dry season dropped to the lowest (average 2.75 mg·C·kg-1 SDW·d-1?0.34 mg·C·kg-1 SDW·d-1), and then continue to rise until the rainy season in July 2015 (an average of 223.27 mg·Ckg-1 SDW-d-1 ?1.28 mg·C·kg-1 SDW·d-1). Soil respiration and the nitrification rate and significant correlation between soil temperature and humidity (p< 0.05), indicating that soil temperature and humidity are affected soil respiration and total nitrification rate the key environmental factors. Soil total nitrogen, ammonium nitrogen and nitrate nitrogen and the total soil respiration and nitrification rate also has significant correlation (p< 0.05), indicating that soil carbon and nitrogen transformation in influenced by soil microenvironment conditions at the same time, also affected by other environmental factors of comprehensive soil. Different artificial forest, the fire nan plantation soil respiration and total nitrification rate was significantly higher than those of the mixed forest and pine forest (p< 0.05), which can be attributed to tree species differences in biological characteristics, nitrogen fixation trees broadleaf fire nan higher litter leaf and fine root biomass and quality, and faster decomposition rate makes the soil nutrient and the substrate of effectiveness is higher than other two kinds of plantation. Compared with other results showed that soil respiration and total nitrification rate, as well as the Q10 values are likely due to vegetation types, site quality, forest age, or there are differences between the different climate zone.(2) According to the dry season, the determination of PLFAs quantity in three plantations in the rainy season, summarizes the dry season, the rainy season changes in relative value, actinomycetes increase the highest, increased by 229.5%, followed by bacteria, up to 176.1%, the lowest for fungi, only to enhance the 158.1%(p<0.05). The comparison of soil microbial experiment, soil microbial the dry season variation:pine mixed forest> micheliamacclurei plantation; soil microorganism in rainy season value change:M.macclurei forest> mixed forest of Masson pine. Principal component analysis showed that the forest species composition and seasonal factors significantly affect soil microbial community structure of forest types. Then, combined with the redundancy analysis showed that:fat single feature phosphatidic acid in different artificial forests, by the soil temperature and humidity affect the P H value of soil environmental factors; analysis on soil physicochemical properties, the characteristics of individual phospholipid fatty acids and soil nitrogen Content is closely related to, and total nitrogen and ammonium nitrogen content was positively related (P< 0.05); also in different seasons, three forest soil fungi/bacteria than the size of the change is for:mixed forest (1.23:1)> Pinus massoniana (1.20:1)> Michelia macclurei forest (1.09:1) (P< 0.05), fire Linan mixed with Pinus massoniana can ensure soil ecological system have the good stability. |
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