Ash trees possess many features that allow them to survive and adapt to changes in their environment. In particular, ashes have several adaptations that make them extremely flood hardy. Their root and leaf structures also enable to them to survive through cold winters, high winds and fire.
Green ashes in particular have developed several unique adaptations that allow them to survive floods. When an area is flooded, the overabundance of oxygen in the water often makes plant respiration extremely difficult, which is deadly for many trees. Young ash trees, however, are able to switch to anaerobic respiration, meaning they are able to function within higher oxygen levels. In fact, in some cases, they may oxidise their rhizospheres -- they allow their roots to let out oxygen when submerged. They may also develop secondary root systems that are more able to survive watery conditions.
White ash has a unique feature that allows it to survive fires. Although the trunk of the tree may be destroyed by forest fires, the roots remain alive. After the fire, the tree will often send up new roots from this portion of the tree, allowing it to survive.
Ash trees are able to survive colder winters due to several adaptations. When temperatures begin to drop, the tree cuts off the water and food supply to its leaves, which in turn causes them to dry out. This is a protective measure, as the large amount of moisture in leaves would make them very susceptible to freezing during cold winters and would leave the tree vulnerable to bacterial and fungal infestations. Additionally, the trees seal off the openings where the fallen leaves attached to the tree to keep out the cold. They also circulate a sugary substance through their branches, which helps to keep them from freezing.
As with many deciduous trees, ashes have very broad leaves. This leaf structure is important, as the larger surface allows the plant to capture more sunlight to complete the process of photosynthesis, in which sunlight is converted to chlorophyll.
Ash trees also have large root systems. In fact, they may extend as far as 3 to 4 feet downward and may occupy a surface as wide as 48 feet. Because their roots are so sturdy, adult ash trees can survive relatively strong winds.