Responses of soil temperature,moisture and respiration to experimental warming in a subtropical evergreen broad-leaved forest in Ailao Mountains, Yunnan
为把握土壤温度对未来全球气候变暖的响应程度,评估气候变暖对亚热带森林土壤呼吸的影响,利用在哀牢山亚热带常绿阔叶林中设置的土壤增温和土壤呼吸人工控制实验2011 2013年的实测数据,通过分析,得到如下结果:环境温度的升高不会改变林内的近地层气温、土壤温度和土壤含水量的年变化和日变化规律;冬季和夜间增温效应大于夏季和昼间;增温会导致土壤含水量降低,雨季的效应大于干季;增温导致的升温效应和降低土壤水分效应具有一定的年变化,但是基本没有日变化;所设置的人工增温控制实验的年平均增温在2.0℃左右,所设置人工控制实验可以达到5 cm 土壤增温2.0 ℃的设计要求,可为其后探讨土壤呼吸对温度升高的响应提供良好的基础保证。
英文摘要:
The soil-surface carbon flux is comparable to that of photosynthesis in terrestrial ecosystems. Much soil carbon flux to the atmosphere is due to rhizosphere metabolism (root respiration) and the decomposition of soil microbes (microbial respiration),which are both very sensitive to temperature. With soil temperatures increasing,soil respiration will increase,thereby accelerating global change. To improve our understanding of the response of soil temperature to future warming and to assess the potential effects of global warming on soil respiration in subtropical forests, we experimentally warmed subtropical evergreen broad-leaved forest soils in Ailao Mountain Southwest, China and measured their respiration. This experiment was conducted at the Ailaoshan Station for Subtropical Forest Ecosystem Studies (24o32'N,101o01'E; 2480 m above sea level) of the Chinese Ecological Research Network, Jingdong County, Yunnan Province. The annual mean air temperature was 11.0℃,with a maximum monthly mean temperature of 15.3℃ in July and a minimum monthly mean temperature of 5.1℃ in January. The site has strong rainy seasons (May to October) and dry seasons (November to April the following year). The average annual rainfall was 1882 mm, with 1607 mm (85.4% of the annual total) in the rainy season and 274.2 mm in the dry season (14.6% of the annual total). The soil is yellow brown in this area. Litterfall accumulates to 37 cm. Soil humus is dark brown and 1015 cm thick. The mineral soil layer is loose and dominated by soil aggregates. Surface soils have high water permeability and water conservation ability, high organic carbon, and a pH of 4.55. Our artificial warming experiment was conducted in a subtropical forest where wind speed and radiation are both low at the surface. A multi-channel automated chamber system was used to continuously monitor soil CO_2 effluxes. The system was comprised of 20 automatic chambers (length 90 cm * width 90 cm x height 50 cm) and a control box,and the 20 chambers were divided into 4 treatments (5 chambers per treatment) : control,litter removal, trenching,and infrared light warming. The soil efflux of each chamber was measured automatically each hour and environmental factors were measured each half hour. When measuring soil efflux, the chamber was closed for 3 min, then opened for 57 min by opening its lid. Thus,environmental conditions (e. g., wind,rainfall,and litterfall) in chambers were similar to those outside. In the artificial warming experiment, variations in soil temperature and soil water content were observed along with soil respiration.