雅鲁藏布江中游松属、冷杉属表土花粉对海拔的指示意义

The Instruction Significance to Altitudes of Surface Pinus and Abies Pollen from the Middle Reaches of Yarlung Zangbo River

通过雅鲁藏布江中游41个表土样品中松属和冷杉属花粉含量与当地松属、冷杉属植物群落分布高度的对比发现,松属花粉含量在50%～60%及以上的样品出现的海拔为2 500～3 200 m,这与当地高山松和华山松群系分布的海拔(2 200～3 500 m)一致,考虑到群落的覆盖度(50%～60%),认为松属含量50%～60%是一个可以指示松属植物群系分布高度的指标。冷杉属花粉含量超过60%(或50%)对应的海拔(3 500～4 200 m)与急尖长苞冷杉群系分布的海拔(3 300～4 300 m)亦是非常一致的,并且也能够很好的代表群落植被的覆盖度(50%～70%)。此外,由于松属和冷杉属花粉产量和重量的差异,松属花粉更容易传播到高海拔地区,而冷杉属花粉则更多的降落在低于急尖长苞冷杉群系海拔分布的地区。

This study focus on the comparing between the percentages of Pinus and Abies pollen from 41 surface samples and they distribution altitude in the middle reaches of Yarlung Zangbo River, then found that its altitude instruction significance. The altitude （2 200 ~ 3 500 m） occurred Pinus densata and Pinus armandii consistent with the samples altitude （2 500 ~ 3 200 m） over 50% ~ 60% percentages of Pinus. Considerating of the vegetation coverage （50% ~ 60% ）, the percentage of Pinus with 50% ~ 60% is a relible index that can indicate the altitude of Form. The elevation between the distribution of Abies georget var. smithii and samples of Abies percentage over 60% （or 50% ） is consistent, and thi~ pollen percentage also can represent vegetation coverage （50% ~ 70% ）. In addition, due to the differences in weight and productivity of Pinus and Abies, Pinus pollen is more easily spread to high altitude regions, while most of Abies pollen is more landing below the distribution area of Form. Abies georgei var. smithii.