植物生态学报 ›› 2012, Vol. 36 ›› Issue (5): 403-410.DOI: 10.3724/SP.J.1258.2012.00403

所属专题: 青藏高原植物生态学:群落生态学

• 研究论文 • 上一篇    下一篇

青藏高原高寒沼泽湿地在退化梯度上植物群落组成的改变对湿地水分状况的影响

李宏林, 徐当会, 杜国祯*()   

  1. 兰州大学生命科学学院干旱与草地生态教育部重点实验室, 兰州 730000
  • 发布日期:2012-05-04
  • 通讯作者: 杜国祯
  • 作者简介:* E-mail: guozdu@lzu.edu.cn

Effect of change of plant community composition along degradation gradients on water conditions in an alpine swamp wetland on the Qinghai-Tibetan Plateau of China

LI Hong-Lin, XU Dang-Hui, DU Guo-Zhen*()   

  1. Key Laboratory of Arid and Grassland Ecology of Ministry of Education, College of Life Sciences, Lanzhou University, Lanzhou 730000, China
  • Published:2012-05-04
  • Contact: DU Guo-Zhen

摘要:

对青藏高原东缘玛曲高寒沼泽湿地分属于15科的47种主要植物进行光合测定, 结合对不同退化类型植物群落的样方调查, 分析了各种植物之间以及不同功能群之间的净光合速率、气孔导度、蒸腾速率和水分利用效率等光合参数的差异。结果表明: 1)玛曲高寒湿地的主要物种在净光合速率、气孔导度、蒸腾速率和水分利用效率4个光合特性参数上的差异显著, 表明各植物种以各自独特的方式适应高寒湿地环境; 在功能群水平上, 各功能群之间的差异亦显著。光合速率从大到小依次为禾草>莎草>豆科和其他双子叶类杂草, 水分利用效率则是莎草>禾草>豆科和其他双子叶类杂草; 2)湿地退化导致其群落组成发生明显改变, 其中最明显的特点是双子叶类杂草的比例大大增加; 而双子叶类杂草普遍较低的水分利用效率将会增大土壤水分通过光合作用的蒸腾散失, 在大气降水对水分补充变化不大的条件下, 这将会进一步加剧群落生境的干旱化, 不利于退化湿地的恢复和附近湿地的保护。研究结果表明, 在湿地保护和退化湿地恢复过程中, 典型湿地土著物种的保存和补充具有重要意义。

关键词: 高寒湿地, 退化, 光合生理特征, 植物群落, 水分利用效率

Abstract:

Aims Wetlands degradation has drawn increased concern recently. Many researchers have reported the changes of plant communities and the relevant degradation mechanism of wetlands. However, few studies have explored the effects of plant community change on the water conditions of swamp meadow. Our objective was to investigate how change of alpine swamp meadow along degradation gradients affects its water conditions.
Methods The study was conducted at the Research Station of Alpine Meadow and Wetland Ecosystems of Lanzhou University (Maqu Branch Station) (33°39′ N, 101°53′ E). We examined 47 species (15 families) selected from a degradation gradient of alpine swamp meadow. Net photosynthesis rate (Pn), transpiration rate (Tr) and stomatal conductance (Gs) were measured simultaneously with a portable gas exchange system LI-6400 (Li-COR, Lincoln, NE, USA). Measurements were performed from 9:00 am to 12:00 am on clear days in mid-July and mid-August, using photosynthetically active radiation (PAR) = 1 800 μmol·m-2·s-1and flow = 750 μmol·s-1. The value of water use efficiency (WUE) was determined by Pn/Tr. We also investigated the cover of different functional groups (grasses, sedges, legumes and other forbs) at different degradation levels.
Important findings The photosynthetic physiology traits were different among species and functional groups (p < 0.01). The sequence of Pn values of functional groups was grasses > sedges > legumes and other forbs, and WUE was sedges > grasses > legumes and other forbs. Species composition of the plant community had been changed due to the degradation of the swamp meadow. The abundance of forbs increased with degradation. WUE was lower for forbs than other functional groups, which implied that more soil water is transpired, exacerbating the drought condition of degraded meadows. Successful restoration requires protection and replenishment of the typical native species.

Key words: alpine wetland, degradation, photosynthetic physiology trait, plant community, water use efficiency