Characteristics of Soil Respiration and its Environmental Factors of Poplar Plantation on Beach Land of the Yangtze River

Soil respiration, especially of forest and wetland ecosystem, plays an important role in the global carbon cycle. Poplar plantation on beach land is a unique artificial ecosystem, which has characteristics of both ecosystems. The characteristics of soil respiration of poplar plantation are rarely reported. Soil CO2 release rates in artificial poplar plantation on beach land of Hunan and Anhui province were measured using Infra Red Gas Analysis(IRGA) technique, and the dynamics of soil respiration rate (SRR) and its controlling factors such as temperature, soil water content (SWC) and vegetation structure under the forest were analyzed. The results showed that the diurnal dynamics of soil respiration presented a single peaked curve with the maximum occurring around 11:00-13:00. The value order of Soil CO2 release rates was Jun-06>Oct-05>Mar-06>Oct-05. The mean value of efflux was 2.285 +/- 0.752 mu mol m(-2) s(-1)(P<0.05, n=13), and the coefficient of variation is 0.544. It implied great spatial differences of SRR in the regions. The sensitivity of soil respiration to the temperature above ground superior to the soil temperature at 5cm-depth. Because the influence from exterior factors was little, the curve of soil temperature at 5cm-depth was gently, that led to indistinct responses of SRR to it. The value of Q(10) of the poplar plantation was 1.282 +/- 0.785(P<0.05, n=13), less than the global level except for wetland. The relationship between SWC and SRR was not good, so the SWC was not a limiting but an influencing factor to the efflux of CO2. Influenced by the high SWC, the gross efflux of CO2 was reduced. The vegetation structure was also one of the important controlling factors. (c) 2011 Published by Elsevier B.V. Selection and/or peer-review under responsibility of School of Environment, Beijing Normal University.