基于WorldView 2影像的矿区植被重建效果评估

植被盖度反映植被质量,是评价矿区复垦土地植被重建效果的重要指标。该文选择安太堡矿区为案例区,基于高空间分辨率World View 2(WV 2)影像新波段,使用混合像元模型和实地数据验证相结合的方法计算得到研究区的植被盖度,并对植被重建效果进行了评估,主要得到以下结论:(1)基于WV 2影像的近红外2波段和红波段,采用混合像元法得到的植被盖度反演值Fc_2与实测值最为接近,相关性最强(R~2=0.934),均方根误差最小(RMSE=0.048);(2)研究区植被重建效果整体较好,中等、较高和高植被盖度区域占研究区的60%以上,低植被盖度仅占22.09%。受植被重建年限和管理措施的影响,不同复垦区域植被重建状况之间存在着差异,内排土场、西排土场、南排土场的植被重建效果较好,而西排土场扩大区植被状况相对较差,其中等及以上植被盖度所占比例依次为75.24%、68.35%、68.20%、22.29%。(3)就植被组合模式看,乔灌草模式重建效果(按冠层盖度)最好,其次是乔草模式,其他模式如灌草、草地、自然恢复地依次降低。土壤表层水分含量随着复垦地植被盖度的增大而增大,说明植被重建状况对土壤表层的水分保持具有重要作用。

Evaluation of vegetation restoration effects in mining areas based on WorldView 2 images

The vegetation coverage fraction reflects the quality of vegetation and is, thus, an important index to evaluate the vegetation restoration effect of reclaimed land in mining areas. This study, considering Antaibao mining areas, evaluated the currency of different vegetation indices using the pixel dichotomy model based on the new band of WorldView 2 (WV 2) images and field-measured data, and then abstracted the vegetation coverage fraction of the study area to indicate the vegetation restoration effect. The results show that (1) with a near-infrared 2 and red-band of WV 2 image, vegetation coverage fraction (Fc₂) as calculated by the mixed-pixel method, was the closest to the field-measured values (R²=0.934,RMSE=0.048).(2) The study areas had been well restored as a whole:the vegetation coverage fraction was moderate-to-high in more than 60% of the area, while in only 22.09% of the area was lower than 20%. Vegetation restoration affected by the duration and management measures differed among the plots:in Inner Dump, West Dump, and South Dump, better vegetation restoration was observed with moderate-to-high coverage, at 75.24%, 68.35%, and 68.20%, respectively, than in the expanded West Dump (22.29%).(3) The vegetation restoration pattern with the combination of grass, shrub, and trees had the best restoration effect, followed by the inter-planting of grass and trees, while the combination of shrub grass, only grass vegetation, and natural restoration had relatively poor effect. The soil moisture rises with increased vegetation coverage, implying that vegetation status plays an important role in soil surface-water retention.