Spatio-temporal Variations Of Global Cultivated Land And Their Effects On Carbon Storage

Global warming has become a primary issue threating human survival and development.Carbon emission caused by Land Use/Cover Change(LUCC)is one of the main causes of global warming.Cultivated land,as a type of land,has various attributes such as natural,social,and economic environment,and is closely related to food security.In this study,30m resolution global cultivated land carbon storage raster data were generated by using the existed high resolution land use data,biomass carbon density data,and SOC density data to probe into the spatial and temporal characteristics of global scale cultivated land changes,explore main driving forces of cultivated land changes worldwide,and reveal the effects of global cultivated land changes on carbon storage.This can provide a theoretical basis and data support for the optimization of land use and ecological patterns at large scales,guaranteeing national food security,stabling economic development,promoting industrial restructuring,and developing emission reduction policies,and is of great significance for achieving the"double carbon"goal.The main research results are as follows.1.The global cultivated land area in 2000 was 18.84×10~6 km~2,the global cultivated land area in 2010 was 19.25×10~6 km~2,and the global cultivated land area in 2020 was 20.00×10~6km~2.From 2000 to 2010,the increased area of global cultivated land was 0.40×10~6 km~2,of which forest was the main source of net increase(0.20×10~6 km~2)in cultivated land,and artificial surfaces the main direction of net decrease(0.04×10~6 km~2)in cultivated land.From2010 to 2020,the increased area of global cultivated land was 0.75×10~6 km~2,of which grassland was the main source of net increase(0.55×10~6 km~2)in cultivated land,while artificial surfaces the main direction of net decrease(0.18×10~6 km~2)in cultivated land.2.From 2000 to 2020,the global cultivated land appeared in most of Europe,eastern and central North America,southeast South America,central Africa,eastern Asia,southern Asia,and southeast Asia.The changes in cultivated land during the period 2000-2020 mainly appeared in central Africa,central North America,northwestern South America,eastern Asia,and southern Asia.3.From 2000 to 2020,the cultivated land area of each continents ranked as follows:Asia,Europe,North America,South America,Africa,and Oceania.Asia and Europe showed an upward trend from 2000 to 2010,and a downward trend from 2010 to 2020.The cultivated land area of the remaining continents showed an upward trend.4.The top 10 countries with the largest net increase in cultivated land area during 2000-2010 were Brazil,Argentina,Nigeria,Tanzania,Australia,Sudan,Paraguay,Russia,Kenya,and Mozambique.The top 10 countries with the largest net increase in cultivated land area during the period 2010-2020 were Brazil,Nigeria,Australia,Mozambique,Mexico,Argentina,the Democratic Republic of the Congo,Niger,the United States,and Chad.5.The cultivated land changes in 123 countries are dominated by social factors,with the most driven by male labor force participation rate;the cultivated land changes in 63 countries are by economic factors,with the most driven by agricultural value added and per capita GDP.6.In 2000,the global total carbon storage in cultivated land was 272.57 Pg,and the SOC95.55 Pg,and the biomass carbon 177.02 Pg.In 2010,the global total carbon storage in cultivated land 278.53 Pg,SOC 97.21 Pg,and biomass carbon 181.32 Pg.In 2020,the global total carbon storage in cultivated land 292.68 Pg,SOC 99.88 Pg,and biomass carbon 192.80Pg.7.From 2000 to 2010,the total carbon released by global cultivated land changes was73.02 Pg,SOC released 12.84 Pg,and biomass carbon released 60.19 Pg.From 2000 to 2010,the total carbon sequestration of global cultivated land changes was 65.17 Pg,the SOC sequestration 12.85 Pg,and the biomass carbon sequestration 52.31 Pg.From 2000 to 2010,the total net carbon of global cultivated land changes was-7.86 Pg,the net SOC 0.02 Pg,and the net biomass carbon-7.87 Pg.From 2010 to 2020,the total carbon released by global cultivated land changes was 77.11 Pg,SOC released 13.85 Pg,and biomass carbon released63.26 Pg.From 2010 to 2020,the total carbon sequestration of global cultivated land changes was 69.29 Pg,the SOC sequestration 16.94 Pg,and the biomass carbon sequestration 52.35Pg.From 2010 to 2020,the total net carbon of global cultivated land changes was-7.82 Pg,the net SOC 3.08 Pg,and the net biomass carbon-10.90 Pg.8.From 2000 to 2020,the highest proportion of total carbon released or stored by the interaction between cultivated land and other land types in the world was forest.From 2000to 2010,the net carbon emissions from the interaction between forest land and cultivated land were the highest,while from 2010 to 2020,the net carbon emissions from the interaction between grassland and cultivated land were the highest.Global cultivated land changes from2000 to 2020 would lead to carbon emission;global cultivated land changes from 2000 to2020 would lead to SOC sequestration;global cultivated land changes from 2000 to 2020would lead to the release of biomass carbon.In general,changes in the cultivated land led to a large amount of carbon emission and cultivated land changes should be considered as carbon sources.9.In 2000,2010,and 2020,the top 10 countries with carbon storage in cultivated land were the United States,Russia,China,Brazil,Indonesia,India,Canada,France,Argentina,and Australia.The carbon storage of cultivated land in all countries except China increased from 2000 to 2010;From 2010 to 2020,carbon storage of cultivated land in Russia,China,Indonesia,India,and France showed a downward trend,while that in other countries showed an upward trend.