摘要
气候变化背景下冻土环境对地上植物群落的影响备受关注。鉴于此,选择了大兴安岭北坡作为研究区,应用双向指示种分析(TWINSPAN)和典范对应分析法(CCA)对大兴安岭北坡不同冻土融深的30个样地进行了群落分类,分析了物种多样性对冻土融深的响应。结果表明,1)研究区30个沟谷冻土样地植物群落可划分为3个群丛组,TWINSPAN的分类结果很好的反映了群丛组的分布与冻土融深的关系,即随着冻土融深由浅变深,群落由柴桦(Betula fruticosa)+狭叶杜香(Ledum palustrevar.angustum)-苔草(Carex subpediformis)群丛组逐渐过渡到柴桦(Betula fruticosa)-苔草(Carex subpediformis)群丛组和柴桦(Betula fruticosa)+细叶沼柳(Salix rosmarinifolia)-苔草(Carex subpediformis)群丛组,并在CCA二维排序图上得到了验证;2)地上植物群落的物种多样性指数随着冻土融深的增加表现出先上升后下降的单峰变化趋势;在50cm<PMD≤150cm时,物种多样性指数较高。研究结果对冻土区的森林管理以及生物多样性保护具有一定地指导意义。
The Great Khingan Mountains, located in northeastern China, feature zonal permafrost. Lying on the southern edge of the Eurasian permafrost boundary, the permafrost region of the northeast portion of the Great Khingan one of the plant communities most sensitive to the effects of global warming. Permafrost is gradually degrading Mountains is from south to north, because of the effects of human activity and environmental changes such as global warming. The degradation of permafrost leads to changes in the characteristics of diversity, and biomass. The impacts of permafrost on permafrost plant communities, such as species composition, species vegetation have become a key research topic in the field of climate change research. However, previous studies of permafrost have mostly focused on the distribution of permafrost, and so the mechanistic connection between permafrost and environmental factors, and the impacts of permafrost degradation on community composition and structure have not been the focus of much quantitative research. Thus, the plant communities of 30 plots on the north slope of the Great Khingan Mountains were classified according to permafrost depth, using two-way indicator species analysis （TWINSPAN） and canonical correspondence analysis （CCA）. Accordingly, the effects of permafrost depth on plant species diversity were analyzed using these plots. The results indicate the following. （ 1 ） Plant communities were categorized into three plant associations, and as the permafrost depths changed along a gradient from shallow to deep, plant associations changed from Betula fruticose ± Ledum palustre var. angustum-Carex subpediformis to Betula fruticosa-Carex subpediformis and Betula fruticosa ± Salix rosmarinifolia-Carex subpediformis. These relationships were validated by CCA ordination. In addition, permafrost melting depth （PMD）, topography, and soil moisture could together explain 38% of the community change. Their combined effect was the biggest explanatory factor for community change. （2） The species diversity index increased trend initially （in shallow permafrost） and decreased as the permafrost melting depth increased. It reached its maximum value at about 50--150 cm deep. When PMD ≤ 50 cm and PMD 〉 150 cm, the species richness and diversity index are low, and the significant difference. Patrick index and melting permafrost depth has significant correlation （R^2= 0.58, P 〈 0.58）. When PMD ≤ 50 cm, the species richness of the communities was higher, at 23.83±2.44; when 50 〈 PMD ≥ 150 cm, it was 26.36±2.01; and when PMD 〉 150 cm, it fell sharply to 21.14±1.57. The Pielou index and Shannon-Wiener index with the increase of the permafrost melts deep appeared a trend of reducing the rise, and when 50〈PMD〈 150 cm, the Pielou index and Shannon-Wiener index value were significantly higher than those of other permafrost melts deep under the index value. The Simpson index values fell significantly when PMD〉 150 cm. This study provides a theoretical basis for the prediction of trends in the variation of plant community composition after the degradation of permafrost. It is also important for the development and implementation of agriculture and forestry in permafrost areas. In addition, it would be an effective guide for forest management and biodiversity conservation efforts in permafrost regions.
出处
《生态学报》
CAS
CSCD
北大核心
2016年第21期6834-6841,共8页
Acta Ecologica Sinica
基金
国家重点基础研究发展计划(2013CBA01807)
中国科学院先导专项(XDA05050200)
国家自然科学基金项目(41371198)
