| Eucalyptus Dunnii is the most important one of the fast-growing and high-lin in china and has developed into an emerging industry.Eucalyptus Dunnii mainly concentrated in southern china because of the lack of good cold-resistant varieties.Even in the northern part of Guangdong and Fujian,Eucalyptus Dunnii was threatened by hypothermia in winter.Dunnii Eucalyptus gives full play to the advantage of fast-growing Dunnii Eucalyptus with its growing speed and good cold endogenous capacities and Eucalyptus to expand the scale of development effectively is of great significance. Cunning hamia lanceolata (lamb.) Hook is a kind of important timber tree with natural distribution and cultivation widely and is a typical subtropical ecosystem in China.Withe the parth of the small-caliber Chinese fir wood market opened,as a result of cost-effective,budding fir updated has become a mainly way to update in the main producing areas.The wet and dry atmospheric nitrogen and sulpur deposition is one of the important input of nitrogen and sulpur in forest ecosystems The researchs about nitrogen deposition on forest ecosystems mainly concentrated in the temperate zone in Europe and North America region and the sulpur deposition and nitrogen and sulpur deposition on forest ecosytems also rare reports.Therefore,in the context of acid deposition globalization,this paper by simulating the atmosphere of nitrogen and sulfur deposition tests of different nitrogen and sulfur deposition levels on the forest litter dry matter and the elements release of C, N, P, K, Ca, Mg released the impact of forest litter decomposition to clarify the global response to acid deposition characteristics and rules of sustainable forest management,especially in Chinese fir plantation E.dunnii and sustainable management and acid deposition on forest ecosystems and the impact of global change provide the basic data and theoretical reference.Dynamic of the Dunnii Eucalyptus and Chinese fir plantation leaf litter decomposition and C, N, P, K, Ca, Mg release under increasing nitrogen and sulfur deposition by the quadratic rotatio-northogonal combination design were studied. The results indicated that:(1)The Dunnii Eucalyptus and Chinese fir plantation leaf litter decomposition was effected by the nitrogen and sulpur deposition significantly. For the 9 treatments of Dunn Eucalyptus plantation,NO1 to NO9,the decomposition coefficients determined by Olson equation were respectively 1.103, 0.837, 0.764, 0.910, 0.854, 1.045, 0.843, 0.845 and 0.915 with average of 0.892 and with the turnover time of 2.950, 3.557, 3.903, 3.284, 3.511, 2.873, 3.555, 3.531 and 3.256 with average of 3.380 a. The average mass remaining ratio were 35.1%, 43.9%, 48.5%, 41.3%, 46.6%, 36.2%, 46.4%, 47.6% and 42.2% with average of 43.1%. For the 9 treatments of Chinese fir plantation,NO1 to NO9,the decomposition coefficients determined by Olson equation were respectively 0.816, 0.710, 0.615, 0.734, 0.649, 0.823, 0.667, 0.577 and 0.727 with average of 0.702 and with the turnover time of 3.704, 4.239, 4.860, 4.103, 4.605, 3.681, 4.514, 5.171 and 4.141 with average of 4.335 a. The average mass remaining ratio were 43.5%, 50.2%, 55.5%, 47.5%, 51.4%, 43.3%, 53.4%, 57.1% and 47.8% with average of 50.0%. The dry matter of Chinese fir litter was difficult to release and the turnover time of the Chinese fir litter was bigger than the Dunn Eucalyptus litter.The main effect of the two factors,nitrogen and sulpur,to the dry matter release was opposite between the Dunn Eucalyptus and Chinese fir plantation with sulpur playing much more important to the Dunn Eucalyptus dry matter release and nitrogen playing much more important to the Chinese fir dry matter release.There wes no significant interaction effects in the first 4 months and the two factors showed a consistent performance 4 months later with the mutual antagonism in the coding range of [-0.5,1.414].(2)The Dunnii Eucalyptus and Chinese fir plantation leaf litter carbon and nitrogen elements release was effected by the nitrogen and sulpur deposition significantly.For NO1 to NO9,there was a decreasing tendency of the carbon remaining rate of the Dunnii Eucalyptus and Chinese fir plantation leaf litter and the nitrogen was rather difficult to release with the basic release model of"release-enrichment-release". For the 9 treatments of Dunnii Eucalyptus plantation,NO1 to NO9,the decomposition coefficients of carbon determined by Olson equation were respectively 0.934, 0.814, 0.810, 0.877, 0.870, 1.025, 0.750, 0.911 and 0.898 with average of 0.877 and with the turnover time of 3.240, 3.714, 3.744, 3.441, 3.496, 2.967, 4.023, 3.335 and 3.368 with average of 3.148 a.The decomposition coefficients of nitrogen determined by Olson equation were respectively 0.325, 0.136, 0.115, 0.255, 0.149, 0.303, 0.224, 0.143 and 0.222 with average of 0.208 and with the turnover time of 9.047, 21.281, 25.325, 11.497, 19.626, 9.672, 13.112, 20.228 and 13.104 with average of 15.887 a. For the 9 treatments of Chinese fir plantation,NO1 to NO9,the decomposition coefficients of carbon determined by Olson equation were respectively 0.684, 0.729, 0.691, 0.671, 0.655, 0.714, 0.670, 0.760 and 0.760 with average of 0.704 and with the turnover time of 4.256, 3.939, 4.062, 4.266, 4.261, 4.021, 4.376, 3.778 and 3.848 a with average of 4.090 a. The decomposition coefficients of nitrogen determined by Olson equation were respectively 0.585, 0.584, 0.600, 0.666, 0.532, 0.627, 0.597, 0.589 and 0.623 with average of 0.600 and with the turnover time of 4.978, 5.070, 5.037, 4.469, 5.659, 4.733, 4.808, 5.029 and 4.736 a with average of 4.947 a. The effect of the nitrogen and sulpur depositon to the litter carbon release was complex and changed in the decomposition course. The Dunn Eucalyptus carbon release was promoted by the middle level nitrogen loads and may be inhibited by the high level sulpur depositon in the early stage and changed to promotion effect later.The Chinese fir carbon release was promoted by the additional nitrogen loads in the coding range of [-1.414, 1.414] and inhibited by sulpur deposition in the coding range of [-1.414, 1] and promoted in [1, 1.414] coding range. The interaction effect was opposite to the carbon release and to the nitrogen release the interaction effect was basically the same.The two factors of nitrogen and sulpur may antagonize to each other in [-0.5, 1.414] to the carbon remaining of the Dunn Eucalyptus litter and to the Chinese fir litter nitrogen and sulpur may mutual enrich in the coding range of [0.5, 1.414]. The two factors may mutual antagonize in [0, 1.414] to the nitrogen remaining of the Dunn Eucalyptus litter and in [0.5, 1.414] of the Chinese fir litter.(3)The Dunnii Eucalyptus and Chinese fir plantation leaf litter Phosphorus elements release was effected by the nitrogen and sulpur deposition significantly and there was no significant effect to the Potassium release. For the 9 treatments of Dunnii Eucalyptus plantation,NO1 to NO9,the Phosphorus release ratio were respectively 65.49%, 55.84%, 50.50%, 59.65%, 51.24%, 63.03%, 55.33%, 51.86% and 58.39% with average of 56.81% and with the Potassium release ratio of 97.34%, 96.92%, 93.83%, 97.24%, 94.83%, 95.68%, 95.63%, 94.13% and 96.77% with average of 95.82%. For the 9 treatments of Chinese fir plantation,NO1 to NO9,the Phosphorus release ratio were respectively 13.81%, 0.47%, 13.58%, 8.39%, -8.61%, 11.29%, -0.49%, -15.73% and 4.19% with average of -0.13% and with the Potassium release ratio of 97.04%, 97.70%, 97.13%, 96.79%, 96.47%, 92.88%, 95.78%, 94.78% and 97.19% with average of 96.20%.(4) There was no significant effect to the Ca and Mg release of The Dunnii Eucalyptus and Chinese fir plantation leaf litter. |
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