The cottonwood forests along the Rio Grande in central New Mexico are a remnant of a unique and diminishing riverside habitat known locally by the Spanish word bosque, and they provide valuable resources for animals and plants. In the past, the Rio Grande moved within its floodplain instead of being confined to a single channel, and the cottonwood forests depended on that movement because annual flooding washed salt from soils, rearranged channels, and sprouted cottonwood seeds. The installation of dams, levees, and ditches has prevented annual flooding, and the remaining fragments of the bosque are drying and dying. Another threat is tamarisk, which early residents planted after removing cottonwoods to slow soil erosion; tamarisks pull huge amounts of water from the soil and away from cottonwood roots, make soils salty, and degrade riverside ecosystems.