摘要
在25年生的马尾松林下分别套种1年生火力楠、闽粤栲、苦槠、格氏栲、青栲和拉氏栲幼苗,经过16年的培育后形成了郁闭的针阔混交异龄林。通过定位监测和取样分析,研究了马尾松林下栽植阔叶树对生态系统氮循环的影响,并以马尾松纯林作为对照。结果表明：在马尾松纯林和混交林中,林木各组分氮含量表现为叶〉枝〉根〉皮〉干;混交林各土层的氮含量普遍高于纯林,尤其是表层土壤（0~20 cm）;混交林生态系统氮的平均总储量为11 431.00 kg/（hm2.a）,年平均存留量为51.24 kg/（hm2.a）,年平均归还量为56.79 kg/（hm2.a）,分别是纯林的1.15、1.93和2.65倍;混交林林木对氮元素的利用系数为0.143~0.238,循环系数为0.451~0.585,周转时间为7.17~15.52年,而纯林中的数值分别为0.133、0.447和16.83年。因此,将现有的纯林改造成混交林可以提高林木对氮的利用率和周转速率。
Six broadleaved forests native to southern China （Michelia macclurei, Castanopsis fissa, Castanopsis sclerophylla, Castanopsis kawakamii, Cyclobalanopsis myrsinaefolia and Castanopsis lamontii ）, were separately planted under the 25-year-old Masson＇ s pine （Pinus massoniana ） plantation and developed into mixed stands with Masson pine after the growth of 16 years. Based on field investigation and experimental analysis, characteristics of the nitrogen cycles in the pure and mixed Masson pine stands were analyzed. In all the seven stands, nitrogen concentrations decreased in the order： foliage 〉 branch 〉 root 〉 bark 〉 stem. In the mixed stands, soil nitrogen concentration was greater than that of pure pine stands, especially in the topsoil （0- 20 cm）. In the mixed stands, average N storage of total ecosystem was estimated at 11 431.00 kg/hm2, annual accumulated N at 51.24 kg/hm2 , and N flux via litterfall and rainwater leachin year, which were 1.15, 1.93 and 2.65 times of the amount of pure stands, respective coefficient in mixed forest ranged from 0. 143 to 0.238, recycling coefficient from g at 56.79 kg/hm2 per ly. Nitrogen utilization 0.451 to 0.585, and recycling period from 7.17 to 15.52 years. In contrast, the three parameters for N cycles in pure pine stands were 0. 133, 0.447 and 16.83 years, respectively. Therefore, transferring pure pine stands into mixed stands can improve N utilization efficiency and accelerate turnover speed.
出处
《北京林业大学学报》
CAS
CSCD
北大核心
2008年第6期52-58,共7页
Journal of Beijing Forestry University
基金
国家自然科学基金项目(30370259)
江西省自然科学基金项目(0630101)
福建省自然科学基金重点项目(B0320001)
关键词
马尾松
混交林
氮含量
氮储量
氮循环
Masson pine
mixed stands
nitrogen concentration
nitrogen storage
nitrogen cycle
