连栽第1代和第2代杉木近熟林水文过程养分动态比较

利用小集水区径流场技术和定位研究方法,在获得连栽两代杉木近熟林的大气降水、穿透林冠水、地表、地下径流量等水文学数据,并测定其养分含量的基础上,研究了连栽两代杉木近熟林水文过程的营养动态特征。结果表明:降水中养分浓度第2代林比第1代林高20.30%—39.64%,养分的输入量比第1代多38.52%;穿透水中养分浓度,第1代和第2代林分别比大气降水中高4.149—4.895 g/kg和4.271—5.605g/kg,雨水对冠层营养物质的淋溶,第2代比第1代高2.94%—21.37%;地表径流中的养分浓度两代林差异不大,地下径流中的养分浓度第2代林比第1代高48.06%—78.87%,径流输出的养分量第2代林是第1代林的1.58—2.61倍;养分地球化学循环中,第1代林养分地球化学循环速率26.75%—29.95%,第2代林37.24%—47.43%,养分地球化学循环的周期第1代林3.3—3.7a,第2代林2.1—2.7a,养分地球化学循环中第2代林的养分流失率是第1代林的1.30—1.72倍,养分的净积累率只有第1代林的73.57%—87.14%。系统持留与利用由外界输入的养分功能上,第2代林低于第1代林。

Characteristics of nutrient dynamic in hydrological processes of first and second rotations of prematured Chinese fir plantations

Based on the small watershed technique and the located observation method, the hydrology data collected of the precipitation, penetrate the canopy water, surface and underground runoff, and determine its nutrient content, which were used for analyzing the nutrient dynamic in hydrologic process on the successive rotations of Chinese fir plantations at near mature forest. The replanting its purpose to reveal functional differences in the two generations of Chinese fir in biogeochemical cycling of nutrients, and study the problem of declining productivity even planted fir plantations provide ideas and evidence. The results showed that the nutrient concentrations in precipitation of the second generation forest was 20.30%-39.64% higher than that in first-generation forest, which accounted in total for 38.52% more input of nutrients in second generation than that in the first generation forest. The nutrient concentrations in the through fall in the forest of the first and the second generation was relatively 4.149-4.895 g/kg and 4.271-5.605 g/kg higher than that in the corresponding atmospheric precipitation, respectively. Rain canopy leaching of nutrients,which the nutrient content was 2.94% to 21.37% higher in the second generation forest than that in the first generation forest after leaching through the canopy. There was not significantly different between the nutrient concentrations in surface runoff of the first and that in the second generation forest. The nutrient concentrations subsurface runoff of second generation forest, however, was 48.06% -78.87% higher than that in the first generation forest, which induced the runoff output in the runoff, the second generation forest was 1.58 to 2.61 times more than that in the first generation forest. The nutrient geochemical rate was 26.75% to 29.95% in the first generation forest, while in the second generation forest the nutrient geochemical cycle was 37.24% to 47.43%, and The nutrient geochemical cycle was 3.3 to 3.7 years in the first generation forest, while was 2.1 to 2.7 years in the second generation forest. The nutrient loss rate of the second generation forest was from 1.30 to 1.72 times higher than that in the first generation forest, and the nutrient accumulation rate in the second generation forest was from 73.57% to 87.14% of that in the first generation forest. As to the retention and utilization in the input of nutrients from the outside, the nutrient retention and utilization efficiency of the second generation forest was lower than that of the first generation forest.