Analysis of Landsat NDVI time series for detecting degradation of vegetation
| Main Author: | Polina Lemenkova |
|---|---|
| Format: | Proceeding |
| Terbitan: |
, 2015
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| Subjects: | |
| Online Access: |
https://zenodo.org/record/2295436 |
Daftar Isi:
- Calculation of vegetation indices, especially Normalized Difference Vegetation Index (NDVI), has become one of the most successful, popular and traditional attempts in biogeographical research methods, because NDVI has certain advantages over other vegetation indices or band combinations. The results of calculations of vegetation indices for studies of land cover types are being repeatedly reported in various papers [1], [2], [3], [4]. Thus, NDVI is less depending on soil properties of the research area as well as to the daytime illumination comparing to simple red-infrared bands combination [5]. NDVI is well adjusted specially for the analysis of vegetation properties, which can be indirectly interpreted from the objects colors, as shown on the raster image. However, the correlation of the results received from the satellite spectral signals may not necessarily precisely correlate with real data on biomass and vegetation quality which is caused by the local climatic settings and biogeochemical background of the research area. To model the NDVI I used Map Calculation tool in command line of the Raster Operations menu in ILWIS GIS, which enables to perform spatial analysis and modeling by combination of queries, arithmetic expressions and overlays of selected raster images. The calculation of the NDVI index is read into the ILWIS spatial analysis menu using following equation: NDVI = (Band4 – Band3) / (Band4 + Band3), where Band 4 is DN values of spectral reflectance in NIR (near infra-red) and Band 3 is DN values of spectral reflectance in VIS. The NDVI was calculated automatically using arguments of images: VegIndex = NDVI (Band3, Band4). Two Landsat bands have been used: Band4, containing red reflectance and Band3 with infra-red reflectance: VegIndex=NDVI(TM_3,TM_4). Other Landsat scenes were classified individually using the same method scheme in ILWIS GIS. The resulting images shows distribution of the vegetation over the Bovanenkovo region within three (3) years: 1988, 2001 and 2011 (Fig.2). The results for the year 2001 show that vegetation has very moderate overall index, reaching value 0,500 as a maximal. The maximal NDVI values in year 2011 are 0.49, while in 1988 it was 0.76, which shows the decrease in the biomass values during the past two decades. The satellite-based monitoring of the northern ecosystems is important tool for detection of the environmental changes. This research presented ILWIS GIS based image processing of Landsat time series covering Yamal area. The results show decrease in overall NDVI values for the study area since 1988 to 2011, which can be caused by the environmental change and anthropogenic factors. The calculated NDVI indicated biomass and can be also used as indicator of “greenness” of the vegetation.
- P. Lemenkova. "Analysis of Landsat NDVI time series for detecting degradation of vegetation". In: Geoecology and Sustainable Use of Mineral Resources. From Science to Practice. Proceedings of 3rd International Conference of Young Scientists (National Research University 'Belgorod State University' (BelSU), Apr. 6–10, 2015). Ed. by A. N. Petin, P. V. Goleusov, and E. I. Makaseeva. Belgorod, Russia: BelSU Press, 2015, pp. 11–13. isbn: 978-5-98242-210-1. doi: 10.6084/m9.figshare.7211795.v1.