When Europeans came to the Americas they introduced exotic plants and animals that greatly affected the land, especially cattle, which were introduced to the páramos in the early 18th century. By the 20th century the growing population of settlers led to an increased demand for land, and páramo ecosystems suffered accordingly. As more land was needed for cattle, fire was used to clear land, and eventually páramos became excessively burned and overgrazed. Both burning and grazing have damaged vegetation, soils, species diversity, and water storage capacity of the páramos. In burned and disturbed sites that were studied in the Andes the pH and phosphorus concentration in the soil are higher than in non-burned sites.