Akademska digitalna zbirka SLovenije - logo
E-resources
Peer reviewed Open access
  • Including land cover change...
    Zhu, Zhe; Fu, Yingchun; Woodcock, Curtis E.; Olofsson, Pontus; Vogelmann, James E.; Holden, Christopher; Wang, Min; Dai, Shu; Yu, Yang

    Remote sensing of environment, 11/2016, Volume: 185
    Journal Article

    Remote sensing has proven a useful way of evaluating long-term trends in vegetation “greenness” through the use of vegetation indices like Normalized Differences Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI). In particular, analyses of greenness trends have been performed for large areas (continents, for example) in an attempt to understand vegetation response to climate. These studies have been most often used coarse resolution sensors like Moderate Resolution Image Spectroradiometer (MODIS) and Advanced Very High Resolution Radiometer (AVHRR). However, trends in greenness are also important at more local scales, particularly in and around cities as vegetation offers a variety of valuable ecosystem services ranging from minimizing air pollution to mitigating urban heat island effects. To explore the ability to monitor greenness trends in and around cities, this paper presents a new way for analyzing greenness trends based on all available Landsat 5, 7, and 8 images and applies it to Guangzhou, China. This method is capable of including the effects of land cover change in the evaluation of greenness trends by separating the effects of abrupt and gradual changes, and providing information on the timing of greenness trends. An assessment of the consistency of surface reflectance from Landsat 8 with past Landsat sensors indicates biases in the visible bands of Landsat 8, especially the blue band. Landsat 8 NDVI values were found to have a larger bias than the EVI values; therefore, EVI was used in the analysis of greenness trends for Guangzhou. In spite of massive amounts of development in Guangzhou from 2000 to 2014, greenness was found to increase, mostly as a result of gradual change. Comparison of the greening magnitudes estimated from the approach presented here and a Simple Linear Trend (SLT) method indicated large differences for certain time intervals as the SLT method does not include consideration for abrupt land cover changes. Overall, this analysis demonstrates the importance of considering land cover change when analyzing trends in greenness from satellite time series in areas where land cover change is common. •All available Landsats 5–8 data were used to analyze greenness trends.•Data from Landsat 8 were not completely consistent with the data from Landsats 5–7.•Landsat 8 EVI values were less biased than Landsat 8 NDVI values.•The total EVI change estimated by SLT was 14.3% higher than CCDC estimation.•On average Guangzhou experienced a 0.0567 increase in EVI from 2000 to 2014.