A Study On Long-term Site Productivity Of Different Forest Types In Jiulongshan Mountain

Abstract: The research focused on plant communities, microorganisms, enzymes, forest floors, organic matter, pH, macro-elements and micro-elements of soil and rooting zone as well as the change of available nutrients in soil, bulk density of soil, capillary porosities under different forest types such as Larix principis-rupprenchtii, Pinus tabulaeformis, Fraxinus chinensis plantations and Tilia, Qeurcus & Popullus secondary natural forest, which based on field investigation and the laboratory work. The research provides foundation for maintaining the stability of soil ecosystems and long-term site productivity through Comparing and analyzing the evolution and degradation of soil ecosystems between plantations and secondary natural forest. The sample plots are located in forest experiment farm of Chinese Academy in Jiulongshan Mountain. The sample plots were designed in four types, which are Larix principis-rupprenchtii, Pinus tabulaeformis, Fraxinus chinensis plantations and Tilia, Qeurcus & Popullus secondary natural forest. The results are as follows: (1) In temperate and warm temperate zone, floristicses under plantations are less than that under secondary natural forest. Among plantations, there are a few floristicses under Pinus tabulaeformis plantation, the plants favoring sunlight are increased and umbatosus are decreased in Larix principis-rupprenchtii and Fraxinus chinensis plantations. The gross micro-organism numbers including bacteria, fungus and actinomycete, as well as activities of hydrogen peroxidase, invertase and urease in soil and rooting zone of plantations are in the decreasing trend, among which the decreasing range for Fraxinus chinensis plantation is big, for Larix principis-rupprenchtii and Pinus tabulaeformis plantation is small.(2)Comparing with secondary natural forest, the quantity and quality of soil organic matter for plantations is reduced, among which the decreasing range of organic matter and humic acid in soil for Fraxinus chinensis plantation is big, for Larix principis-rupprenchtii and Pinus tabulaeformis plantation is small. Establishment plantations after Harvested secondary natural forest, the quantity and quality of organic matter in soil are reduced.(3)Organic acids generated from decomposing forest floor and rooting secretions of Larix principis-rupprenchtii and Pinus tabulaeformis plantations reduce the soil pH, which result in soil acidification.(4)Comparing with secondary natural forest, available nitrogen, available potassium, available zinc and available copper in soil of plantations are in the decreasing trends, among which the decreasing trends of Pinus tabulaeformis and Fraxinus chinensis plantation are obvious, but the changes of Larix principis-rupprenchtii plantation are small. Some nutrients in soil of Larix principis-rupprenchtiip plantation are a little bit higher than that of Fraxinus chinensis and Tilia, Qeurcus & Popullus secondary natural forest. Based on the changes of available nutrients, the difference between the secondary natural forest and Larix principis-rupprenchtii plantation is small, but the decreasing trends of Pinus tabulaeformis and Fraxinus chinensis plantation are obvious.(5)Comparing with secondary natural forest, available nitrogen, available potassium, available iron, available zincum and available cuprum in soil of rooting zone are in the obviously decreasing trends, but the changes between Larix principis-rupprenchtiip plantation and secondary natural forest are little. Available potassium, iron, manganese, zincum and cuprum in rooting zone of both secondary natural forest and plantations are increased, those metal elements are activated in rooting zone.(6) In the period of growth, available potassium, available iron, available manganese, available cuprum in soil of plantations are decreased, but the decreasing ranges are different for different tree species. Otherwise, available nitrogen in soil of Larix principis-rupprenchtii plantation and available phosphorus in soil of Fraxinus chinensis plantation are higher tha...