摘要
对河南内乡宝天曼自然保护区内 35年生的天然次生锐齿栎林生态系统的营养元素循环进行研究 ,结果表明 :所测定系统中的 N、P、K、Ca、Mg、Fe、Na、Mn、Zn、Cu1 0种营养元素积累总量为 1 0 387.894kg·hm- 2 ,土壤库贮量 8880 .70 9kg·hm- 2 ,占 85 .49% ;植物体贮量 1 5 0 7.1 82 kg·hm- 2 ,占 1 4.5 1 % ,其中活植物体占 90 .5 6% ,凋落物占 9.44%。系统中 1 0种营养元素年吸收量 2 0 7.5 4 5 kg· hm- 2 ,年存留量1 0 5 .2 85 kg· hm- 2 ,年归还量 1 0 1 .65 1 kg·hm- 2 ,年积累速率为 77.8986kg·hm- 2 ;年归还量占年吸收量48.98% ,表明系统中营养元素的循环处于良好的平衡状态。 1 0种营养元素的平均利用系数为 0 .1 85 ,平均周转期为 9.98a。其中 P、N、Mg、Na、Mn的周转期较短为 4～ 8a,K、Ca、Fe、Cu周转期较长为 1 0～ 1 6a,Zn的周转期最长为 1 7.4a。
This paper studied the element cycle of a 35-year-old %Quercus acutidentata% (Fagaceae) forest in Baotianman Natural Reserve, Neixiang county, He'nan Province. The forest is a secondary vegetation type in the northern deciduous forest region. Investigations were carried out in a 20×20 m2 plot in which trees were measured and ranked according to Kraft (1884) method during 1993~1995. The stand biomass was determined and the element contents of N, P, K, Ca, Mg, Fe, Na, Mn, Cu and Zn were analyzed in trees, shrubs, herbs, litters, soils, as well as in different tree organs.;The results showed that there were element allocation differences in the different tree organs. Ca, Na, N, K and Mg concentration were the highest in leaves, barks and roots, but the lowest in stems. However, P was relatively higher in branches, roots and leaves, while Fe was higher in roots. The average element content in the layer of shrubs and herbs was higher than that in the layer of trees. Nevertheless, tree layer accumulated the largest amount of elements for the highest biomass. The concentration of Ca, N, P and Fe was relatively higher in branches, leaves and barks than in stems. ;The element accumulation in the tree layer aboveground was obviously higher than that underground with the exception of Fe and Zn. The element accumulation orders was Ca> K> Na> N> Mg> P> Mn> Fe> Zn> Cu in the tree layer and was stem> root> bark> branch> leaf> fruit in the different tree organs. In the shrub layer, N, Ca, Na and K contents were relatively higher than the other elements. Herb layer showed a lower elemental accumulation. The total element accumulation in the litter was 143.9591kg·hm -2, accounting for only 10.76% of that in the tree layer. Those elements such as Ca, Na, N and K were highly accumulated in soils, plants and litters. The total amount of the 10 elements in soil was 8880.709 t·hm -2, but only 1688.451 t·hm -2 in the surface layer (0~18cm). It showed that the element cycle in the forest ecosystems was affected not only by the plants but also by the forest soils.;In this forest ecosystem the annual elemental accumulation rate in the tree layer was 77.8986 kg·hm -2·a -1, in which the rate of the tree stems was 17.854 kg·hm -2·a -1 and of the leaves was 35.2539 kg·hm -2·a -1. It showed that the tree leaves have a higher element accumulation rate and played a very important role in the element cycles. The litter returned 101.651 kg·hm -2·a -1 elements in which Ca was the highest, K, Na, N, Mg, Fe and P were relatively lower. The returned amount reached a peak in autumn and followed by in winter, in spring, and in summer. The total annual uptake amount of the 10 elements was 207.545 kg·hm -2·a -1, while the retained was 105.285 kg·hm -2·a -1. The annual returned amount reached to 48.98% of that the uptake. The average utilization coefficient was 0.185. The elemental utilization coefficient showed that the less the utilization coefficient the longer the turnover period. Zn has the longest turnover period of 17.4 years but the lowest utilization coefficient; Ca, K, Cu and Fe have a 10~16 years period but a quite higher utilization coefficient; Na, P, N, Mg and Mn have the shortest period of 4~8 years but the highest utilization coefficient.
出处
《生态学报》
CAS
CSCD
北大核心
2003年第8期1488-1497,共10页
Acta Ecologica Sinica
基金
国家林业局"八五"攻关课题资助项目 (编号 93 -0 8-0 60 2 )~~
