Research On The Temporal-spatial Differences Of Carbon Source And Carbon Sinks Of Farmland Ecosystems In Shandong Province

Since the industrial revolution,the development and utilization of nature by humans has increased,resulting in a significant increase in the concentration of greenhouse gases in the atmosphere and the aggravation of Global warming effect.This paper taked Shandong Province,a major agricultural province,as the research object.Based on the Statistical Yearbook data of Shandong Province from 2000 to 2017,the carbon u sources and sinks of farmland ecosystems in Shandong Province and various cities were estimated.The carbon absorption pathway is mainly for photosynthesis in the whole life cycle of crops.The carbon emission pathways mainly include CH₄ produced during rice growth,N₂O produced by major crops during planting,and agricultural inputs.The time difference of carbon sources and sinks of farmland ecosystems in Shandong Province was described,and GIS software was used to analyze the characteristics of spatial distribution.By analyzing the impact factors of carbon sources and sinks in farmland ecosystems,measures to increase carbon sequestration and mitigate carbon emission.In order to provide a scientific basis for the adjustment of agricultural structure and the development of low-carbon and green agriculture in Shandong Province.The results were summarized as follows:?1?The carbon absorption of farmland ecosystem in Shandong Province showed"increase-decrease"trend.The carbon absorption increased significantly from 2000 to2011,with an average annual growth rate of 3.24%,and decreased from 2011 to 2017,with an aAverage annual decline rate of 1.34%.Carbon absorption intensity rised from4.61 tons/ha in 2000 to 6.09 tons/ha in 2017.The changing trend of grain crops and horticultural crops tends to be the same as that of the whole,but the carbon uptake of horticultural crops decreases rapidly at the later stage.Grain crops are the main carbon absorption.To source,and wheat and corn contribute the largest.In terms of spatial distribution,the total carbon absorption of Heze City and Dezhou City is in the forefront of the whole province,and the carbon absorption intensity of Dezhou City is the highest,which is 6.94 tons/ha.In Laiwu City,the total amount of carbon absorption in Weihai City is small,while the carbon absorption intensity in Weihai City continues to decline,reaching 4.52 tons/ha in 2017,with the smallest carbon absorption intensity.According to the spatial distribution of the whole province,the total carbon absorption and carbon absorption intensity in southwest Shandong are significantly higher than those in eastern Shandong.?2?The total carbon emission and carbon emission intensity of farmland ecosystem in Shandong Province show the trend of"increasing and fluctuating and decreasing"with the passage of time.From 2000 to 2007,the total carbon emission and carbon emission intensity respectively increased from 8.3149 million tons.0.72 tons/ha increased to 9.8937 million tons/ha,0.92t/ha,and the increase rate of carbon emission intensity was higher than the total carbon emission.From 2007 to 2017,the total carbon emission and carbon emission intensity decreased from 9.8937 million tons,0.92t/ha to 8.7969 million tons and 0.79t/ha,respectively.the decreasing rate of carbon emission intensity was higher than that of 0.92t/ha.Total carbon emissions.Among all kinds of agricultural production inputs,the application of chemical fertilizer is the main source of carbon emissions.The carbon emissions per unit area of chemical fertilizers,pesticides,agricultural film,diesel oil and agricultural machinery converge with the total carbon emission intensity,and the carbon emissions caused by irrigation per unit area are increasing.In terms of spatial distribution,the carbon emissions and carbon emission intensity of Weifang,Heze,Linyi and other agricultural development cities are relatively small,and the total carbon emissions of Dongying City,Laiwu City and other areas with small sown area are relatively small.Weihai City,Yantai City and other economically developed Shandong East area carbon emission intensity is higher.?3?The change trend of net carbon sink of farmland ecosystem in Shandong Province is the same as that of carbon absorption.From 2000 to 2011,it showed an upward trend,with an average annual growth rate of 3.96%.It is higher than the growth rate of total carbon absorption.The net carbon sink intensity rised from 3.84 tons/ha in2000 to 5.30 tons/ha in 2017,with an average annual growth rate of 3.1.77%The results show that Shandong Province has achieved remarkable results in carbon sequestration and emission reduction and the development of green ecological agriculture.Through regression analysis,it is found that the correlation between net carbon sequestration and total carbon absorption is 99.9%,but the correlation between net carbon sequestration and carbon emission is small.In terms of spatial distribution,the net carbon sequestration and the intensity of net carbon sequestration are high in southwest Shandong and low in eastern Shandong.Its Heze City has the largest net carbon sequestration and growth range,Weihai City,Laiwu City has the lowest net carbon sequestration,and the growth rate is the smallest.As far as the net carbon sink per unit area is concerned,Dezhou City is the highest,Weihai City,Yantai City and other coastal areas are lower.?4?Through the combination of quantitative and qualitative analysis,the influencing factors of carbon source/sink in farmland ecosystem are analyzed,and it is found that crop yield,crop type,farming methods and agricultural production input,Natural conditions are important factors affecting carbon source and carbon sink.At the same time,in order to analyze the relationship between net carbon sequestration,economy,population and other social conditions,grey relational analysis was used to analyze the relationship between net carbon sequestration and agricultural economic development level?X1?,agricultural production efficiency?X2?and cultural level of agricultural labor force?X3?.The relationship between per capita planting area?X4?and other factors was obtained,and the order of correlation degree was as follows:R3>r4>r1>r2.?5?In view of the present situation of farmland ecosystem in Shandong Province,the main measures of carbon sequestration and emission reduction are as follows:optimizing fertilizer method,improving farming method,combining straw returning to field with combined application of nitrogen fertilizer,etc.,which will help to improve the carbon sequestration capacity given by ecosystem.