GRAZING AND ITS RELATIONSHIP WITH NITROGEN COMPOUNS IN Prosopis laevigata IN NORTHERN MEXICO FORESTS

Mesquite forests Prosopis laevigata functions as a nourishment source mainly for beef cattle. This study was carried out in order to find if mesquite forests are affected by the grazing, particularly on nitrogen components due to its importance in the vegetal growth and tree development. The objective of this study was to determine if the extensive grazing has influence over the concentration of the nitrogen components amino acids and proteins in mesquite forest. Root and stem samples in adult trees were taken monthly during twelve months in two pure mesquite stands, one of them with grazing activity. The total soluble proteins (TSP) and total amino acids (TA) concentrations were determined by visible UV spectrophotometry. The results shown that grazing has assimilation effects in nitrogen components in trees of the mesquite wild populations. The root and stem where there is no grazing activities showed greater concentrations of nitrogen components in comparison with the site where grazing is done as an anthropogenic activity.