| Subalpine fir forest (Abies faxoniana) in western China plays important part in subalpine forest located in high elevation and low latitude area. What’s more, subalpine fir forests have principle ecological functions such as water conservation, species conservation and other important ecological functions. Its diverse vegetation and soil association provide a natural laboratory for forest soil science studies. The understory environment of subalpine fir forests, which is low temperature, high humidity, seasonal freezing and thawing, is very different from coniferous forest in the the same latitudes due to its natural climatic conditions (equivalent to cold temperate climate) and the properties of construction species of dark coniferous forest.In recent years, these natural forests have large number of death, which may be the results of natural succession. But on the other hand, wheather the process of soil in these coniferous forest become the driving force behind these phenomena is not known. Therefore, this case take subalpine fir soil as the research object, and using the forest soils position method, focus on nutrient dynamics of the special soil types. The aim of this case is exploring the influence of soil forming process on soil nutrient. The results indicated that,(1)The soil available nutrient in the study point have significant seansonal variation. soil ammonium nitrogen, available potassium content of maximum leached layer (A2) and maximum deposition layer (B2) layer in the rainy season (August and May) was significant higher than that in the dry season (November and February), nitrate nitrogen is vice versa. During the rainy season, ammonia nitrogen, phosphorus, potassium in performance for the A2layer was significantly higher than that in B2layer, but in the dry season, their content of B2layer and A2layer was close, or the content of B2was significantly higher than that of A2layer.(2) In soil solution, the available nutrients in the soil solution is ammonia nitrogen and potassium, available phosphorus. Nitrate nitrogen almost non-existent. The metal element is based on the solubility of the relatively high potassium, sodium, iron, manganese majority. For soil solution in different soil layers, the concentration of ammonia nitrogen in leaching layer still higher. Potassium in the soil solution, potassium, sodium, aluminum and variation of elemental including iron, manganese showed consistent variation, which have the seasonal changes with soil moisture. The content in leached layer is higher than that in deposited layer in rainy season and visa in the dry season. (3) The content of soil organic carbon content in leached layer is greater than that in the deposition layer in each season. Soil total nitrogen, total phosphorus content in B2layer is higher than that of A2layer. Potassium, sodium and other mineral total amount change with the seasonal variation. During the rainy season, the leached layer above the deposition layer, while in dry season, deposited layer higher than the leached layer. Calcium, magnesium, copper, zinc, nickel and other mineral elements content did not change significantly in leaching and deposition horizon. In the process of soil organic matter moves down from the organic layer, bleached layers appeared transient accumulation due to anaerobic microbial activity and slower mineralization.(4) Comprehensive analysis, bleached podzolic soil did not appear on serious impoverishment caused by ashing or rinsing. Ammonia nitrogen, nitrate nitrogen, available phosphorus available nutrients only changed with the seasonal variation of soil moisture. The results of soil nutrients in soil solution concentration have the same regular with above-metioned. |
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