Drought is a phenomenon that can have severe impacts on tree health and survival. It is a prolonged period of warm and dry weather, which leads to a shortage of water in the soil, causing trees to become dehydrated. During a drought, trees may experience a lack of water availability, which can limit growth and photosynthesis, increase susceptibility to pests and diseases, and ultimately lead to mortality.
One of the primary effects of drought on trees is reduced water uptake and transport. Trees’ root systems are responsible for absorbing water and nutrients from the soil. When water is limited, the roots cannot absorb enough water to adequately supply the tree’s needs. As a result, the tree’s hydraulic system becomes disrupted, which can affect the water balance within the tree and lead to wilting, leaf loss, and the collapse of branches or entire trees.
When trees experience water stress, they prioritize the allocation of water to vital functions, such as maintaining turgor pressure and performing photosynthesis. Non-essential functions, such as growth and reproduction, are down-regulated until water supply is adequate enough to support the functions. As a result, trees produce fewer new leaves and branches, which leads to reduced photosynthesis and carbon storage. Limited photosynthesis means that the amount of energy available for growth and maintenance decreases, which can limit the tree’s ability to produce energy and support its growth and maintenance needs.
When trees become water stressed, they may also become more susceptible to pests and diseases. Drought-stressed trees may have weakened immune systems and reduced resistance to pathogenic fungi and insects, which can lead to infections and further damage. Drought weakens the bark of trees, making it easier for fungi and insects to invade.
Prolonged periods of drought can decrease a tree’s ability to recover and rebound after the drought is over. Trees can begin to die of the natural process called the “water stress-induced mortality”. However, this process takes time but if the drought continues for long enough, the trees might not survive. This can lead to long-term declines in growth and survival that can accelerate the impacts of other environmental stressors, such as air pollution or invasive species.
In summary, droughts can have severe impacts on tree health and survival. Water stress can limit water uptake and transport, reduce photosynthesis and carbon storage, increase susceptibility to pests and diseases, and decrease recovery and resilience following a drought event. It is essential to consider the potential impacts of drought when managing trees and to implement management strategies that can help mitigate these effects. Some of the strategies include regular and appropriate irrigation, mulching, and pruning to reduce the amount of stress trees have to endure, especially during drought conditions.