| As an important non-wood forest resource in China,bamboo forest plays an important role in the regional ecosystem.Due to its unique biological characteristics,growth characteristics,and high carbon sequestration capacity and potential,the research about bamboo forest has became a hot topic of the international community.In this study,time series data of 1984-2014 Landsat5 TM and Landsat 8 OLI in Zhejiang Province were used to extract bamboo forest distribution information over time,and analyze regular patterns of the dynamic changes of the area,revealing the changes of the area and land use patterns of bamboo forests,as well as the spatiotemporal evolution of carbon storage in bamboo forests and the impact of LUCC on carbon storage of the bamboo forests.This study mainly discusses from the following aspects:1.Spatiotemporal dynamics and changes of information and land use of bamboo forest in Zhejiang Province over the past 30 years.Data preprocessing was performed on the acquired Landsat data;Combined with samples data,the maximum likelihood supervised classification method was used to label the land use types in Zhejiang Province,and based on which the bamboo forest distribution information was extracted.2.Spatial distribution and temporal-spatial evolution of carbon storage in Zhejiang Province over the last 30 years.With information extracted from pre-processed Landsat remote sensing as independent variables and carbon stocks acquired from sample plots as dependent variables,regression analysis were conducted to establish prediction models between remote sensing factors and biomass,based on which the distribution map of carbon reserves and accuracy assessment was generated.Then its spatial and temporal distribution characteristics and trends were analyzed.3.The land use transfer matrix in Zhejiang Province over the past 30 years.The maps of land use types of Zhejiang Province obtained from the study were used to establish land used transfer matrices.Combined with bamboo forest distribution information and related carbon storage information in each year,the land use transfer matrix were analyzed for revealing the effects of land use type changes on the temporal and spatial changes of the carbon stocks in bamboo forests.The main conclusions are as follows:1.The bamboo forest information extracted from time series Landsat data achieved a high accuracy rate.The overall accuracy,user’s accuracy and kappa coefficient reached 75%,91% and 0.7,respectively.And the statistics area of bamboo forest which was extracted from our methods was highly correlated with actual area of bamboo in Zhejiang Province with accuracy over 95%.2.The area of bamboo forests in Zhejiang Province increased for over the past 30 years,except Taizhou city.The changes and dynamics of area of the Taizhou City were-33.04% and-1.10%,respectively;the changes in other regions were 49.74% and 48.76 %,1085.15%,80.69%,108.97%,217.34%,155.63%,90.21%,15.29% and 24.99% respectively,with an average annual change rate of 1.66%,1.63%,36.17%,2.69%,3.63%,7.24%,5.19%,3.01%,0.51%,and 0.83%.3.The correlation coefficient(R)of the estimation of the carbon storage of bamboo forests was above 0.6 for all years.Annual average carbon storage density from 1984 to 2014 was 9.47,9.07,7.84,7.42,6.57,10.95,15.25,and 19.05 Mg C/ha,respectively;Total carbon stock for each year was 5.06,5.03,5.39,5.13 5.14,8.42,15.72 and 16.94 Tg C.4.Among the land use changes in Zhejiang province over the past 30 years,the increase in the area of broad-leaved forests was the most remarkable.The propotion of the area of broad-leaved forests in Zhejiang Province increased from 15.86% to 24.64% from 1984 to 2014 with the average annual growth rate of 0.29%.The area of coniferous forests decreased significantly,and the proportion of coniferous forests in the Zhejiang Province decreased from 37.64% to 17.53% from 1984 to 2014,a decrease of 20.11%,with a average annual reduction rate of 0.67%;propotion of the area of bamboo forest in the Zhejiang Province increased from 5.04% to 8.56% from 1984 to 2014,which only increased by 3.52% with an average annual growth rate of 0.12%.5.During the expansion process of bamboo forest in Zhejiang province over the last 30 years,the land use changes of coniferous forest,broad-leaved forest and cultivated land contribute a lot to the increase of bamboo forest area.The biggest contribution rate generated from coniferous forest reached 56.81%.The contribution rate of cultivated land and broad-leaved forest was 13.26% and 25.26%,respectively,while other land types contributed little to the expansion of bamboo forests.6.Affected by LUCC,the county with the largest and lowest increase in total carbon storage in Zhejiang during the 30 years was Hangzhou City and Jiaxing City,respectively,of which Hangzhou City’s carbon storage increased from 0.96 Tg C in 1984 to 3.47 Tg C in 2014.increased nearly 4 times,with an average annual increase of 0.08 Tg C;Jiaxing City has low carbon storage due to lower bamboo area and carbon density. |
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