Análisis de tendencias temporales del índice mejorado de la vegetación (EVI) en dos ecosistemas de la subcuenca del río Chambo durante el período 2013-2020.

Abstract

The research aimed to analyze the improved vegetation index (EVI), in two ecosystems of the Chambo river sub-basin, during the period 2013-2020. It also was carried out to develop new knowledge about the dynamics that both ecosystems manage to contribute to their preservation. A total of 93 images were obtained from the Google Earth Engine platform by downloading satellite images from Landsat 8. ArcGis 10.8 software was used to delimit the study area, where the EVI index was determined using the following formula: 2.5 *(img1["B5"]-img1["B4"]) /(img1["B5"]+6*img1["B4"]-(7.5*img1["B2"]) +1). A maximum monthly average EVI value for the HsNn02 ecosystem of 0.36 was obtained in October and December, and its minimum value of 0.29 in January. As for the BsSn01 ecosystem, it presented a maximum value of 0.28 in July and a minimum value of 0.22 in August. The trend of the EVI was analyzed through the non-parametric method of Mann Kendall with the TREND software, which allowed us to observe the most reliable trends among the rainfall of the ecosystems under study. It was reflected that the HsNn02 ecosystem reported non-significant increasing trends in January, March, June, August, September, October, November, and December, and BsSn01 was reported in March, April, August, September, and November. A proposal of measures for the management and conservation of these environments was made. Finally, it was identified that the HsNn02 ecosystem had a higher average EVI of 0.32 in the 2013-2020 period due to the high vegetation cover it has. So, it is recommended to analyze precipitation and temperature with more prolonged periods.