大通河源区多年冻土环境的空间格局及其变化趋势研究

As a special thermal state of soil, permafrost is sensitive and changeable to temperature. Permafrost environment, defined as the ecologically surficial environment in permafrost regions, is becoming increasingly vulnerable under the global climate warming. The change of permafrost environment will result in a considerable impact on the vegetation and soils in the involved environment. On the basis of the extensive studies on permafrost in the source region of the Datonghe River, on the northeastern edge of the Qinghai-Tibet Plateau, this project aims at establishing three observation transects at upper, middle, and lower parts of the source region to form a monitoring network for permafrost environment. The monitoring network is consisted of sites for monitoring both thermal regime and moisture content of permafrost and active layer in typical units of geomorphology and ecology. Some principal indices in vegetation and soils will be surveyed at various ecological sites. Based on the series of principal parameters in permafrost, vegetation and soils, the spatial pattern of permafrost environment in the source region will be analyzed. According to the depth of the active layer and permafrost temperature, a permafrost sequence is set up to quantitatively analyze the relationship between permafrost and characteristic parameters of vegetation and soil. By means of space-time converting principle, the spatial pattern and the relationship involved in the permafrost environment will be used to predict the changing trend of the permafrost environment under a changing climate.

多年冻土是一种对温度敏感和易变的特殊地质体，作为多年冻土区的表生环境，多年冻土环境在全球气候变暖的影响下变得更加脆弱。多年冻土状态是多年冻土环境各要素中最主要的参与因子和驱动因素，其变化将对区内植被和土壤产生显著影响。以祁连山大通河源区作为研究区，以前期工作为基础，在上、中、下段分别建立涵盖主要典型地貌、生态单元的多年冻土地温、活动层监测横断面，构成源区多年冻土状态监测网络。基于建立的监测断面，开展植被、土壤调查，获取完整的多年冻土环境各要素基本状态参数，分析源区多年冻土环境的分布规律和空间格局。以多年冻土活动层厚度和冻土地温为主导指标构建多年冻土变化序列，定量研究植被、土壤特征指标对多年冻土特征指标的依存关系。在掌握多年冻土环境各指标因子的空间格局和依存关系基础上，借助空间-时间转化方法，预估气候变化背景下多年冻土环境的变化趋势。

多年冻土区环境指在自然和人类活动影响下，由多年冻土及其活动层冻融作用所塑造的独特表生环境。多年冻土状态是多年冻土环境各要素中最主要的参与因子和驱动因素，其变化将对区内植被和土壤产生显著影响。以祁连山大通河源区作为研究区，以前期工作为基础，分别建立涵盖主要典型地貌、生态单元的多年冻土地温、活动层监测横断面，构成源区多年冻土状态监测网络。基于建立的监测断面，开展植被、土壤调查，获取完整的多年冻土环境各要素基本状态参数，分析源区多年冻土环境的分布规律和空间格局。研究植被、土壤特征指标对多年冻土特征指标的依存关系。在掌握多年冻土环境各指标因子的空间格局和依存关系基础上，预估气候变化背景下多年冻土环境的变化趋势。研究主要获得以下结果：1）给出了大通河源区多年冻土地温及活动层分布状态，提出了活动层水热过程的年内变化规律，初步预测了源区多年冻土地温变化趋势；2）阐明了源区生物多样性、浅土层理化性质在源区的空间分布格局，提出了多年冻土发育特征与地貌、植被之间的相互作用关系，初步预测了植被、土壤性质随冻土地温变化的演替规律；3）分析了源区人为活动对多年冻土环境的影响程度。