Soil Greenhouse Gas Emissions Characteristics Of Intensive Management Phyllostachys Pubescens And The Relationship With Fertilizer

Global warming is one of the hottest issues in global change researches, due to the rapid increase of concentration of greenhouse gases in the atmosphere. Carbon and nitrogen cycles of forest ecosystem play an important role in the atmospheric concentration of greenhouse gases. Bamboo is an important forest resources in southern China It has great annual biomass accumulation and carbon sequestration capability. In recent years, with the implementation of effective forest, intensive cultivation was applied in bamboo forest, accounting for nearly 40% of the total bamboo forest. , Researches for greenhouse gases emission of Intensive management of bamboo and its relevant impact factors- can be used to evaluate the importance of bamboo forest ecosystems in mitigating climate change effects and provide the basis for taking relevant measures. Bamboo forest under extensive management and evergreen broadleaf forest were chosen as the control in this study. CO₂, CH₄ and N₂O fluxes of bamboo forest soils under intensive management were observed,using static chamber -gas chromatography. The seasonal and daily variation of CO₂, CH₄ and N₂O fluxes, and the relationship between CO₂, CH₄ , N₂O fluxes and soil water-soluble organic carbon (WSOC), water-soluble organic nitrogen (WSON) were discussed. Meanwhile, greenhouse gas emissions of bamboo forest soil under different fertilization treatments were studied. . The main conclusions are as follows:1) Consistent seasonal variation of soil respiration was found in bamboo forests under intensive and extensive managements and evergreen broad-leaved forest , as the highest soil respiration occurred in summer, and it decreased in autumn and winter, but increased again in spring. Significant difference of soil respiration rates (P <0.01) among the these three type of forests was observed. The average soil respiration rate of bamboo forest under intensive management was38.4% higher than that in the evergreen broad-leaved forest, and 33.6% higher than that under extensive management. Daily variation also existed in soil respiration rates, showing relatively high rate in day time and low in night time, but the highest and lowest soil respiration rates were found at different time points in different seasons. Temperature and water content in soil were the main factors which significantly influence the CO₂ fluxes in soils. A significant correlation (P <0.01), between soil respiration of above three forest types and air temperature or ground temperature was found -Soil respiration rates of bamboo forest under Intensive Management and evergreen broad-leaved forest and soil water content were significantly correlated (P <0.01),bamboo Forest under extensive management and soil water content was significantly correlated (P <0.05), temperature and moisture are the dominant factor of soil CO₂ emission flux. Whether based on the various formation temperature or air temperature calculation, the order of temperature sensitivity Q10 value are as follows: Bamboo Forest under extensive management > Bamboo Forest under Intensive Management> evergreen broad-leaved forest; The relationship between WSOC and soil CO₂ emission of intensive management was not significant. The relationship between WSOC and soil CO₂ emission of bamboo forest under extensive management and evergreen broad-leaved forest was significant. The relationship between WSON and soil CO₂ emission of three types of forest land were not significant.2) The seasonal variation and day change of soil CH₄ emission flux of bamboo forest under intensive and extensive management and evergreen broad-leaved had no obvious rule, and significantly vary between each period. The CH₄ emissions values were negative, implying the CH₄ sink, the average of CH₄ emissions rates were as follows: evergreen broad-leaved forest> extensive management Bamboo Forest> Intensive Management, The relationship of three kinds of forest land are not significant. The relationship with atmospheric temperature, each layer soil temperature, soil WSOC, WSON and soil water were not significant.3) Soil N₂O emission rate of bamboo forest under Intensive and extensive management and evergreen broad-leaved forest showed a consistent seasonal variation, which included the high peaks from, June to-September, a small peak in November but from December to next May emissions maintained at a lower value, even negative. The average soil N₂O emission rate under Intensive Management was 131% higher than that of evergreen broad-leaved forest, 149% higher than that of Bamboo Forest under extensive management, soil N₂O emission rate was significant between the three different forests. The day change of soil CH₄ emission flux of bamboo forest under intensive and extensive management and evergreen broad-leaved had no obvious raw, and vary significantly between each period. Soil N₂O emission rate and soil temperature and air temperature levels Intensive Management and evergreen broad-leaved forest were significantly (P <0.01), The relationship between N₂O emission rate of bamboo forest under extensive management and soil temperature at 5cm, 10cm, 20cm deepth e was significantly (P <0.05), However, the relationship between soil N₂O emission rate and the surface temperature or atmospheric temperature was not significant. Soil N₂O emission rate of the three forest types and soil moisture had some relevance, but did not reach significant level. Temperature is the dominant factor of soil N₂O emission in the regional scale , while soil water content was non-limiting factor of . Soil N₂O emission of Intensive Management rate was significantly correlated with soil WSOC, while no significant correlation between WSON, evergreen broad-leaved forest was found on the contrary. Soil N₂O emission rates of bamboo under extensive management and WSOC, WSON did not reached a significant level.4) Soil CO₂ and N₂O emissions in different fertilizer treatments in Bamboo Forest showed significant differences (P <0.05). Along with changes in fertilizer, CO₂ emissions were significantly increased. Single application of urea and applied superphosphate and potassium chloride can increase CO₂ emissions, but increased marginally. With the changes in fertilizer, N₂O emissions showed a significant increase in the same trend, single application of urea on the impact of N₂O emissions is very significant.