Zhou Li

Evapotranspiration of Phragmites communis community in Panjin wetland and its control factors

Abstract Based on the data in the whole year of 2005 using microclimate gradient observation, eddy covariance observation, and plant ecophysiological observation at Panjin Wetland Ecosystem Research Station, Institute of Atmospheric Environment, China Meteorological Administration, the daily evapotranspiration variation and the control factors of the Phragmites communis community are analyzed. The results show that daily evapotranspiration variation among different months can be expressed as a single-peak curve that is lower in the morning and evening, and higher around noon. Meteorological and biological factors affect the evapotranspiration obviously. According to the correlation analysis, the evapotranspiration variation of Phragmites communis wetland has good correspondence with such environmental factors as net radiation, air temperature, surface temperature, relative humidity, wind speed and soil moisture. Regression analysis indicated that the major factors during the growing season include net radiation, soil moisture, relative humidity, air temperature and surface temperature, while the factors during the non-growing season include net radiation, soil surface temperature and wind speed. At the same time, growth situation and biological characteristics of vegetation have significant effects on the evapotranspiration of Phragmites communis , especially the leaf index and leaf conductance.

Toward a general evaluation model for soil respiration(GEMSR)

Soil respiration is an important component of terrestrial carbon budget. Its accurate evaluation is essential to the study of terrestrial carbon source/sink. Studies on soil respiration at present mostly focus on the temporal variations and the controlling factors of soil respiration, but its spatial variations and controlling factors draw less attention. Moreover, the evaluation models for soil respiration at present include only the effects of water and heat factors, while the biological and soil factors controlling soil respiration and their interactions with water and heat factors have not been considered yet. These models are not able to accurately evaluate soil respiration in different vegetation/terrestrial ecosystems at different temporal and spatial scales. Thus, a general evaluation model for soil respiration (GEMSR) including the interacting meteorological (water and heat factors), soil nutrient and biological factors is suggested in this paper, and the basic procedure developing GEMSR and the research tasks of soil respiration in the future are also discussed.