A new algorithm to determine the spatial coverage of carob (Neltuma piurensis) by ecological floor: Chira-Piura River Basin case

The carob tree (Neltuma piurensis) is characteristic of the forests of northern Peru, withstand extreme climatic events such as “El Niño” and droughts, in addition to the influence of climate change, affecting its distribution of coverage at different altitudes. The objective of this article is to propose an algorithm to determine the Spatial Coverage of Carob by Ecological Floor (SCCEF) in the Chira-Piura River Basin, Peru. The method used consisted of measuring the spectral signature of the carob tree with the FieldSpec4 spectroradiometer at three sampling points corresponding to the localities of Cardal, Lancones and Macacará, located on different ecological floors. The comparison of the spectral signatures for Cardal and Lancones gives an R² = 0.9459, for Cardal and Macacará an R² = 0.9866 and for Lancones with Macacará an R² = 0.9469, which allows an accurate identification of the carob tree in the satellite images. The Mann-Whitney-Wilcoxon U test validates the spectral signatures extracted from the satellite images with the spectral signatures measured with the spectroradiometer at Lancones (p-value = 0.9705 >α = 0.05), Cardal (p-value = 0.9819 > 0.05) and Macacará (p-value = 0.7959 > 0.05). The results show that the SCCEF in the Tropical (T) ecological floor represents 1.55 % of the T area, in the Tropical Pre-Montane (TPM) ecological floor it is 1.47 % of the TPM area, in the Low Tropical Montane (LTM) ecological floor it is 0.78 % of the LTM area, in the Montane (M) ecological floor it is 0.69 % of the M area and in the Paramo (P) ecological floor it is 0.35 % of the P area. Therefore, the SCCEF decreases in each ecological floor as its altitude increases.