Lactating trees are important to all forests, including the Amazon rainforest.
Nursing trees are large, fast-growing trees that provide shelter for smaller trees and plants as they grow. These trees are a fundamental part of forest ecology throughout the world, from the Amazon rainforest to the dense alpine forests of Europe, and are also ecologically important in some other regions, such as the desert. In addition to being seen in the wild, nursery trees are also sometimes used by gardeners who want to protect young plants in the early stages of growth to ensure they remain strong and healthy.
In the wild, a dead nurse can be beneficial to the rest of the forest, as it can provide food or shelter for other plants and animals.
A nursing tree provides various types of protection. The first is shelter from the sun and distraction from predators, with many insects and similar predators preferring to feed on larger, nutritious trees. Nurseries also protect younger plants from wind and dust storms and attract larger predators such as deer, allowing the tender new growth of young plants to remain undisturbed.
Nutritious trees can protect tender plants from animals like deer.
Eventually, a nursing tree will die, allowing the younger tree to grow. In a natural forest, the dead tree could naturally decompose, contributing to the buildup of organic matter in the forest and providing nutrition and shelter for countless plants and animals. In managed forests, dead wood is often removed to reduce fire risk, and as a result, the forest tends to be less dense and less diverse because fewer species find an environment in which to thrive.
In a forest, a nursery tree may be a different species from the younger plant or tree, or it may be the same species. It is not uncommon to see multiple plants competing for space and resources under nourishing trees, with one plant eventually suffocating the others by cleverly exploiting the resources. Outside the forests, the nurseries are used by plants such as the saguaro cactus, which takes root and spends its young life in the shade of a nurse before finally killing it by taking away most of its available resources.
Gardeners sometimes create their own nursery trees by planting tender seedlings in the shelter of a well-established tree. The mature tree shelters the plant until it is big enough to grow on its own and gives the garden some texture and depth at the same time. Some plants also prefer shady environments, so in hot, sunny climates, a nursery tree can allow a gardener to grow these plants.