韶山针阔叶混交林凋落物层的淋溶及缓冲作用

在韶山森林设立4个10m×10m的标准样地,分别收集凋落物、凋落物层淋滤液和冠层穿透水,研究了韶山森林凋落量季节动态,凋落物淋滤液和冠层穿透水特征以及凋落物层对酸沉降的缓冲作用.结果表明:(1)韶山森林凋落高峰出现在秋季,凋落量随着海拔增加而增加;(2)凋落物淋滤液中盐基阳离子浓度除夏季K ＞Ca2 外,其余季节均为:Ca2 ＞K ＞NH 4 ＞Mg2 ＞Na ,与冠层穿透水中阳离子浓度分布基本是一致的;(3)除Ca2 外,凋落物淋滤液和穿冠水中各阳离子浓度相关性显著,K 达到了极显著相关水平,证实了韶山森林通过凋落物养分归还的K 主要来自森林冠层的滤出;(4)除个别点外,凋落物淋滤液中各阳离子总浓度较冠层穿透水均有不同程度的增加,秋季增幅最大,冬季次之,这与凋落物量变化一致;(5)韶山森林冠层穿透水pH值变动范围为4.58～7.13,最低值出现在冬季,最高值出现在夏季,凋落物淋滤液pH值变动范围为5.02～6.69,均高于韶山表层土壤pH平均值5.0,且最低值出现在春季,最高值出现在秋季;(6)冬季凋落物淋滤液pH值较冠层穿透水均增加,增幅范围在0.06～1.35之间,而其他季节(除样地C的秋季外)pH值均有所下降,这表明韶山森林凋落物层冬季具有较强的酸缓冲作用,而其他季节由于盐基阳离子的滤出不足以抵消凋落物本身分解产生的有机酸类物质的酸化作用,而使凋落物淋滤液pH值降低.

The eluviations and acid buffering effect of litterfall in Shaoshan conifer and broad-leaved mixed forest

A total of four 10×10 m2 standard sampling plots in Shaoshan forest were chosen, and litterfall, litterfall leaching and throughfall were collected respectively for this study. The seasonal dynamics of litterfall and its effect on acid deposition, as well as the characteristics of litterfall leaching and throughfall, were studied. The research results showed that: (1) The quantity of litterfall in autumn is larger than that of other seasons in Shaoshan forest, and the quantity of litterfall increases along with the altitude increases; (2) Concentration of each base cation in other seasons is in the order of Ca2+ >K+ >NH+4 >Mg2+ >Na+ besides K+ >Ca2+ in summer, which is consistent with the trend in throughfall; (3)There is a remarkable pertinence between the concentrations of base cations in litterfall leaching and in throughfall except for Ca2+, yet K+ concentration reached the tarnal salient pertinence level, which approves that the K+ reverting to soil by litterfall comes from forest canopy leaching mostly in Shaoshan forest; (4) Besides some individual spots, the concentration summation of all base cations in litterfall leaching is higher than that in thoughfall in various degrees, and the increase range in autumn is the biggest followed by that in winter, which is consistent with the quantity change of litterfall; (5) The change scope of pH value in throughfall is 4.58-7.13, the minimum value appears in winter, and the maximum appears in summer, while the change scope of pH value in litterfall leaching is 5.02-6.69,which is higher than the average pH of surface soil layer(pH 5.0), but the minimum value appears in spring, and the maximum appears in autumn; (6) The pH of litterfall leaching at each study plot increases in winter, about 0.06-1.35 higher than throughfall pH, but decreases in other seasons(barring plot C in autumn),which indicates that litterfall in Shaoshan forest is a fine acid-buffering system in winter, however, because the base cations leaching from litterfall is not enough to counteract the organic acid produced by litterfall decomposition in spring, summer and autumn, so the pH of litterfall leaching is going down in these seasons.