The cottonwood trees that live along the river from about where Santa Fe, NM is to Truth or Consequences, NM (about 160 miles) are known as the largest cottonwood forest in the world. Most of the trees along the Rio Grande River are mature and aged trees. Most are 40 to 100 years old and the tallest are about 80 feet tall. The trees are not naturally reproducing as they used to due to non-native trees like salt cedar and Russian olive trees taking over. The non-native spices are being removed from this area. Plus the river is damned at a few places and drained off into irrigation ditches for farmland (including the hay I buy for my horses) which means there isn't the flooding along the banks of the river anymore to help seedlings and young trees grow. Much is being done to help the cottonwoods reproduce and not die off.