Soil Respiration And CO₂Sink Of Grasslands At Urban Areas

Global warming resulted from rising atmospheric concentrations of Carbondioxide （CO₂） and other greenhouse gases; it’s become the international hot issue.The effect of carbon cycling in the soil ecosystem on global climate change isintensive. Terrestrial ecosystems are a major part of soil carbon pool and play animportant role in global carbon cycling. Terrestrial ecosystems can transfer betweencarbon source and sink. The key of solve the global climate change is to accuratelyestimate the net carbon source/sink function of terrestrial ecosystems. Therefore,global climate change has led to a widespread interest in the inputs and losses ofcarbon from soils.Among terrestrial ecosystems, urban areas play an important role in climaticchanges. Soil is a major source of the production of atmospheric CO₂.Given the largeorganic carbon reserves stored in urban soil, the release of CO₂from soil may exert apositive feedback on climate changes. Small changes in the magnitude of urban soilrespiration could have a large effect on the concentration of CO₂in the atmosphere.Urban green space is helpful for urban carbon cycling to derive optimal carbonfixation effects. Store carbon dynamics and carbon sink function of urban soil play animportant role in urban development.In2010-2011, we investigated spatial pattern soil respiration and soil carboncycle in different land-use in Shenyang, Liaoning province, China. The analyticalresults showed that soil respiration as an important component of urban carboncycling is influenced by many factors that vary spatially.In order to more accurately estimate the net carbon source/sink function of urbanecosystems, establish the research framework of urban carbon cycling and provide theresearch method of urban carbon sink. The study combination with developing policyand administrative model to propose the policy to improve the urban carbon sinkfunction. Analyze the quantity of carbon in vegetation profiles of various land-usesystems, Vegetation with multi-structure, Vegetation with simple–structure, andsingle vegetation pattern. The major analysis factors are the carbon input and output of vegetation and soil. With the balance calculation, total carbon input is149.951t,260.617t,892.491t,5606.136t, total carbon output is49.23t,82.9t,355.06t,1745.92t, respectively. The net carbon budget is1169t. Vegetation withmulti-structure was the best. The results confirm the carbon sink effective of urbangreen space. The spatial distribution in different land-use and urban green space inShenyang is uneven and complex. The land-use planning aims at the urbandevelopment. Meanwhile, capture the soil respiration variability characteristics andinfluencing factors in urban green-land. The results indicated that soil respiration hasapparent seasonal and annual variation laws, its expresses in a single peak curve. Soiltemperature and soil moisture are main influence factors of soil respiration.Exponential regressions model and linear equation were established to describe therelationship between soil respiration rate and soil temperature （R²=0.9） and betweensoil respiration rate and soil volumetric water （R²=0.4）. The soil organic mattercontent one of soil fertility index has a notable relation with soil respiration rate.Vegetation with multi-structure has the lowest soil respiration.