Being the largest carbon pool of the forest ecosystem, soil carbon is a very important component of the carbon cycle in the system, and being a vital part of the soil respiration of the terrestrial ecosystem, soil respiration of the forest ecosystem influences significantly the global carbon balance. However, so far little research has been done on soil respiration of the forest ecosystems in southeastern Tibet. Therefore, in order to investigate soil respiration and its influencing factors relative to type of the forest ecosystem, a field experiment was conducted using an LI-8100 (Nebraska, USA) to measure soil respirations in four different types of forests [Alpine shrubs (AS), Sabina saltuaria (SS), Rhododendron forest (RF) and Abies georgei var. smithii forest (AGSF)], typical of the Sygera Mountains of the Southeast Tibetan Plateau, for analysis of soil respiration dynamics and their major affecting factors therein. Results show that the soil respirations varies sharply in a day and with the seasons. Diurnally, CO₂ emission flux follows an apparent one-peak pattern of peaking around 16:00 and bottoming around 06:00, while seasonally, it did another of beginning to rise in June when the weather turns warm and the vegetation starts to grow in June, peaking in July, when the air temperature is the hottest in a year in that region, and starting to decline in September, when the air temperature begins to descend. In the four types of forest ecosystems, soil respiration rate during the vegetation growth season is positively related soil temperature of the surface layer (10 cm) to a varying extent, but not so much to soil moisture content. In terms of soil respiration rate, the 4 different types of forest ecosystems follows an order of AGSF > RF > SS >AS. The determination coefficient of the relationship between soil respiration and soil temperature varies with the type of the forest ecosystem in the range of 0.47~0.72, demonstrating that the relationship reaches the significant level. On such a basis, it can be concluded that soil temperature is a primary constraint on soil respiration and soil water plays a secondary role. Type of the vegetation or ecosystem also affects soil respiration in the region, which causes differences between AS, SS, RF and AGSF in seasonal variation of soil respiration (p < 0.001). The Q₁₀ value of soil respiration is higher at high elevations than at low elevations. The findings indicate that in the case of global warming in the future, soils higher in elevation might contribute more CO₂ to the atmosphere. In short, the findings may serve as reference for the study on rules of the variation of soil respiration in forest ecosystems and mechanisms for controlling its affecting factors, and are sure of some important significance to budgeting of global carbon and assessment of regional carbon sources and pools.