Validation of a methodological strategy for the qualitativeevaluation of semiarid rangelands in Zacatecas

Abstract

Rangeland degradation due to mismanagement practices in the extensive system for cattle and the need for monitoringrangelands continuously, leads to seek for methodologies which may be easily and quickly applied. In order toaccomplish such objectives, methodologies must be based upon qualitative indicators. Such methodology has beenapplied broadly using 17 indicators that represent soil, water and vegetation attributes. This study was carried outin the State of Zacatecas and included 34 sites located randomly in the grassland with four repetitions by site. Datawas analysed by principal components and a semivariogram and maps were generated by Kriging. Further, mapswere compared to reference maps, which were calculated by quantitative methods. First map was associated torangelands general health condition. The reference map was estimated from NDVI values. The second componentrefers to runoff, and the third component was associated to water erosion induced by bare soil. Those two werecompared to reference maps estimated from mathematical models. Coincidences among maps were as 59.2, 31.2 y17.2 %, which were the variance values estimated by principal components, and allowed to validate correspondencebetween them. Categorical data were not different (P>0.05). Low cost and easy methods are helpful and should bevalidated for use them when no other methods are available.