The Differences And Influence Factores Of Soil Respiration On Different Land-uses In A Hilly Aera Of Nouth China

The hilly areas of north-China are an ecological barrier to North China Plain, is also a key region of the forest ecological project of returning farmland to plantation and afforestation in barren hills. In the sunny days of Nov.2009 to Oct.2010, to take an evaluation on ecological benefits to the ecological development of this region, enrich the middle latitude data of the global carbon flux observation, offer a reference to the forecasting of global climate change, play an important reference role in the different comparison of soil respiration on different land uses in similar climatic region or in hilly region, the differences of soil respiration rate between Robinia psedudoacia plantation that returning farmland to plantation and farmland ,as well as among Platycladus orientalis plantation,Quercus variabilis plantation and Abandoned land, were measured with the static chamber-gas chromatography method in the south hilly region of North China.The main results are as follows:(1)A significant seasonal variation on soil respiration rates were showed between Robinia psedudoacia plantation and farmland. In the non-growing season, average soil respiration on the plantation was 0.597μmol·m(-2)·s(-1), less than the farmland(0.665μmol·m(-2)·s(-1)) about 10.2% lower;in the growing season, average soil respiration on the plantation was 3.551μmol·m(-2)·s(-1), less than the farmland(3.880μmol·m(-2)·s(-1)) about 8.5%. Because of CO2 emissions, so returning farmland to plantation has significant improvement to climate change.The influence to soil respiration on the plantation and farmland, soil temperature and water content (0～5cm) showed some inconsistences. In the non-growing season, the soil temperature explained above 90% seasonal variations of soil respiration on both the plantation and farmland and had no significant correlation with the soil water content.But in the growing season, the soil temperature only explained 70.5%-79.4% and then the soil water content could explain 24.9% seasonal variations of soil respiration on the farmland,even obvious interaction between Ts and SW. However, there was no significant correlation between the soil respiration rate and soil water content in the studied plantation.In different seasons, there was no consistency on Q₁₀, as an evaluation to sensitivity or dependency of soil respiration on different ecosystems , between the plantation and farmland. In the non-growing season , Q₁₀ of the plantation soil respiration was 3.554,less than 4.170 of the farmland;but in the growing season , Q₁₀ of the plantation was 2.380 more than 1.826 of the farmland Q₁₀.(2) Quercus variabilis plantation afforested on barren hills had a significant effect on CO2 emissions. In the non-growing season and growing season, soil respiration on Quercus variabilis plantation less than the abandoned land , about 19.5%,40.2%, respectively.Platycladus orientalis plantation afforested on barren hills had a significant effect on CO2 emissions also. In the non-growing season , with the seasonal changes of air temperature, the evolution of soil respiration rate on the plantation(0.494μmol·m(-2)·s(-1))lower about 13.8% than the abandoned land (0.573μmol·m(-2)·s(-1)) presented an appearance of"V"; but in the growing season, the seasonal variation curves of soil respiration on the plantation and abandoned land both had a single peak, and average soil respiration on the plantation was 3.658μmol·m(-2)·s(-1),less than the abandoned land(6.363μmol·m(-2)·s(-1)), about 42.5% lower.(3)In the whole studied period, average soil respiration rate on deciduous plantation(Quercus variabilis) was higher 3.1% than coniferous plantation(Platycladus orientalis).But in the different season, the results were different. In the non-growing season, average soil respiration rate on coniferous plantation(Platycladus orientalis) was 0.494,higher 7.2% than deciduous plantation(Quercus variabilis);while in the growing season, coniferous plantation(Platycladus orientalis) was lower 3.7% than coniferous plantation(Quercus variabilis).Both Q₁₀ the two plantation Q₁₀ increased with decrease of soil temperature. In the non-growing season , Q₁₀ of coniferous plantation was higher than deciduous plantation, but in the growing season, there was an opposite result.At range of 10～25%, coniferous plantation Q₁₀ were increased with the increase of soil volumetric water content; but there was no linear pattern on deciduous plantation Q₁₀, only at range 15～25%,the Q₁₀ were more than others.