Effects Of Forest Edge And Land Use/Land Cover Change On Biomass Carbon Dynamics In Chinese Fir Forests Of Southeast China

The Jiangle county state-owned forest farm is situated in Fujian province,China.It has an area of 2246.7 km2 and lies between 117°05'-117°40'E and 26°26'-27°04'N.The area has a humid tropical monsoon climate,with marine and continental climate characteristics.The mean relative humidity is 81%and the frost free period is 287 days.The area is characterized by red,fertile,moist and loamy soil.The average annual precipitation of the county is 1699 mm,and an average annual temperature of 1 8.7?.The recorded woodland of the forest farm is 1887 km2,which constitutes 83.9%of its geographical area.The primary species in the forest farm are Chinese Fir,Moso bamboo,and Masson pine.The dominant tree species is Chinese Fir.(1)Monitoring and mapping forest carbon is critical for informing climate change mitigation measures.Evidence indicates that forest edges hold less carbon than the forest interior.In this study,using field inventory data from a Chinese fir forest ecosystem in southeast China,the carbon at forest edge and forest interior at different elevations was measured.The results showed a significant increasing trend in carbon with elevation.The results also revealed that forest edges had significantly lower carbon than the forest interior.Carbon density values varied between 265 Mg C ha-1 at forest edges to 320 Mg C ha-1 at forest interior.The study highlights that ignoring edge effects overestimates carbon density by 9.46%.These findings suggest that edge effects should be given proper consideration during national forest carbon inventory.Furthermore,we recommend the establishment of permanent sampling plots along forest edges for precise and accurate carbon accounting.(2)In forest ecosystems,soil organic matter facilitates carbon sequestration and serves as a sink for atmospheric CO2.Carbon in forest soils plays an important role in mitigating global climate change.Soil carbon density was measured at three depths(0-20,20-40,and 40-60 cm)in four different elevation classes sites at the forest exterior and forest interior in the sub-tropical forests of southeastern China.Results showed that soil organic carbon(SOC)varied between 46.48 and 83.12 Mg ha-1 at forest exterior and 50.18 and 90.68 Mg ha-1 at forest interior in different elevation classes.A significant increasing trend in soil organic carbon was found with an increase in elevation at both forest exterior and forest interior.Similarly,a positive correlation between soil organic carbon and elevation was observed at forest exterior(R2=0.87,P=0.0001)and forest interior(R2=0.93,P?0.0001).The percentages of soil carbon at 0-20,20-40,and 40-60 cm depths at forest exterior and forest interior were 47.24-52.76,47.23-52.77,and 46.95-53.05%respectively.Soil bulk density was directly related to soil depth and inversely related to elevation at forest exterior and forest interior.Overall the mean SOC at forest exterior and forest interior was 60.83 Mg ha-1 and 68.20 Mg ha-1 respectively.The study showed that there is a 5.7%difference in soil carbon density between forest exterior and forest interior which highlights the fact that ignoring edge effects may lead to overestimation of soil carbon density.(3)Forest carbon monitoring and projecting is important for climate change.Hear,using field inventory data and remote sensing techniques,this study analyzed the changes in carbon density with spatiotemporal land-use and land cover changes during 1997,2007,2017 and a simulation of 2027.The results highlights that biomass and carbon density values was 432 Mg ha-1 and 280 Mg ha-1 respectively.In addition,the carbon density value increase from 5406 Gg to 5600 Gg between 1997 and 2027.During the study period,land-use and land cover changes indicates that forestland changed from 19308 ha to 20001 ha,farmland from 1974 ha to 1279 ha,built-up land from 294 ha to 722 ha,and barren land from 662 ha to 223 ha.The mean annual biomass and carbon density gain were 10 Gg yr-1 and 6 Gg yr-1 respectively.Our results pinpointed the importance of land management activities of increasing forest area in view of managing forest carbon for climate change.Moreover,this study will provide evidence to inform decision-makers particularly involved in ecological protection,planning for land use change and forest management.