The Greenhouse Gases Source/sink Characteristics Of Farmland Ecosystem In Hubei Province And Analysis Of It's Influencing Factors

The farmland ecosystem in the terrestrial ecosystem is most affected by human activities and its carbon reservoir is more active than other systems.This study takes the farmland ecosystem of Hubei Province as the research object,estimates the crop carbon absorption,farmland greenhouse gas emissions and soil organic carbon storage,explore the characteristics and internal changes of farmland ecosystem sources and sinks,clarify the main contributors to the system's sources and sinks,propose greenhouse gas emission reduction and fixed measures and suggestions,and provide theoretical basis for policy The main findings are:?1?From 2007 to 2017,the overall change in greenhouse gas emissions of farmland ecosystems in Hubei Province showed a three-stage development trend.The change trend can be divided into three stages:The first stage is the rapid growth stage?from 2007 to2010?,Increased from 22.435 million tons CO₂-eq in 2007 to 26.014 million tons CO₂-eq in 2010;The second stage is the slow growth stage?from 2011 to 2014?,with an average annual growth rate of 1.53%.;The third stage?2015?2017?is in a phase of slow decline and negative growth,from the greenhouse gas emissions of 25.974 million tons CO₂-eq?2015?to the greenhouse gas emissions of 24.804 million tons CO₂-eq?2017?.?2?The greenhouse gas emissions and intensity of farmland ecosystems in cities?districts?of Hubei Province are quite different.The greenhouse gas emission intensity per planting area?CF_C?and the greenhouse gas emission intensity per unit of grain production?CF_Y?in cities such as Suizhou and Ezhou is too high.The CF_Crange of greenhouse gas emission intensity indicators of farmland ecosystems in Hubei Province is5.11?5.56 t CO₂-e/ha,and the fluctuation range of CF_Yis 0.87?0.97 t CO₂-eq/t.?3?The total carbon absorption of rice was the highest,followed by wheat.Rice?44.01%?,wheat?14.11%?,rapeseed?10.66%?and corn?9.24%?accounted for a higher proportion of total carbon absorption.?4?The carbon absorption of crops in Hubei Province is much higher than the greenhouse gas emissions of farmland,and in the unit year,the farmland ecosystem showed the characteristics of sinks;From 2007 to 2017,the cultivated soil showed a carbon sink,and the increment of soil organic carbon was 13.52 Tg C.?5?N₂O emissions from agricultural land are the leading factors that cause fluctuations in the total amount of greenhouse gas emissions from farmland ecosystems.The greenhouse gas emissions of farmland ecosystems have an exponential correlation with the amount of fertilizer application.The types of crops planted and soil organic carbon density have important effects on the source/sink of farmland ecosystem.