Effect of coal mining on vegetation disturbance and associated carbon loss

Vegetation is an important part of the environment but may be subjected to disturbance in areas close to coal mines. This results in a slowing of the rate of biomass growth, which is caused by fading of vegetation. Simultaneously, carbon stored in vegetation is constantly released, weakening vegetation ability to act as a carbon sink. Indirect release of carbon during coal mining processes is difficult to measure and is often neglected in carbon accounting. In this work, these measurements are performed for a real case study. Within the study area, factors that affect vegetation were divided into: natural factors; human surface activities; and coal mining, with each of these directly reflected in the spatial and temporal variation of the Normalized Difference Vegetation Index (NDVI). To clarify the relationship between coal mining and local vegetation damage, high spatial–temporal resolution remote sensing images were created using the spatial and temporal adaptive reflectance fusion model. Data showing the mine coalface and the variation of vegetation at Xinzhouyao coal mine allowed identification of influential factors. Quantized synthetic effect values of NDVI from coal mining and changes in local climate were then evaluated. Using a theoretical analysis of carbon released from vegetation, the net primary productivity (NPP) and biomass loss of vegetation were calculated. Results showed that fluctuations in vegetation NDVI as a response to changes in local climate were positively correlated with the average NDVI value. Vegetation disturbance caused by coal mining leads to loss of biomass and decreases the ability of vegetation to absorb atmospheric CO2. From 2001 to 2010, loss of vegetation biomass owing to coal mining was 2,608.48 t with annual rates of biomass loss of 33.48 gC/m2 year. Over the same period, the amount of atmospheric carbon absorbed by vegetation was reduced by 1,925.23 t with annual vegetation NPP loss of 24.71 gC/m2 year. Comparing these figures with the amount of coal produced, this calculates the carbon release from vegetation owing to coal mining at Xinzhouyao coal mine as 77.568 g/t. Because much of the carbon in lost biomass is recycled to the soil, the biggest impact on the carbon balance of vegetation near coal mines may be attributed to a reduced ability to absorb atmospheric CO2. These results may be useful for further analysis of the impact of mining on local environments and for the calculation of appropriate ecological compensation.