Caring for Trees in our Mediterranean Climate
Our community would look barren if not for mature trees.
July 17, 2012
Our community would look barren if not for mature trees. Canopies that create shade and cool the air by transpiration of moisture from leaves help humans to withstand summers in Sacramento’s hot Mediterranean climate. There are only 5 Mediterranean climates in the world: Parts of Australia, South Africa, Central Asia and Chile are the only areas in the world that share our particular climate. Summers in these areas are hot and dry and the soil is generally clay. Plants and trees adapted to these dry environments absorb moisture retained in clay soils via tiny root tips and root hairs. Large plants, like mature trees, may not show signs of stress for years. Consider the following to maintain a healthy mature trees in our climate.
Water: Select plants that do not have high water requirements. If you choose plants that need more water, create specific planting areas away from plants that do better in Mediterranean climates. Use only the amount of water that plants require. Overwatering destroys roots and prohibits moisture absorption. Excess water will also create an environment for disease.
Aeration: Allow time between watering to allow soil to dry slightly. Many mature trees and shrubs may only need water on a weekly, bi-weekly or monthly basis during the non-rainy months. Plants absorb water through capillary action, meaning oxygen must be present in the soil for root tips to “suck” up water.
Protection: Do not pile soil, bark chips, rock, or any material around the base of trees. The crown of the tree where the trunk meets the roots should be just above the soil line. Additionally, avoid using string trimmers at the base of trees. Weed trimmers often cause damage to the bark of the tree making the tree susceptible to decay. Trees may stand upright for many years having considerable decay that goes unnoticed. When they “suddenly” fail, it is discovered that decay at the base has been happening for years.
Pruning: Small amounts of pruning over time done to industry standards helps to create a healthy structure and a longer lived tree. Heavy or diseased limbs can fail due to neglectful attention to pruning. Over-pruning and topping are damaging to trees, costly, generally ugly and can create dangerous trees. A tree canopy is designed to make the right amount of carbohydrates needed for health. When over-pruned, roots use up carbohydrates that are not replaced regularly causing the leaf canopy to receive less nutrients and water. Generally trees are pruned during the winter months. Some amount of summer pruning can be desirable to reduce excess limb weight. Some trees may lose branches during the summer when canopies are at their heaviest.
Consistency: Plants do not respond well to change or to being asked to live in inhospitable environments. Watering and pruning amounts and timing make a difference.
Mature trees create harmony in our Mediterranean environment. With the help of Certified Arborists and Consulting Arborists, your mature tree can be an asset to our community. Learn how to hire Certified Arborists. The American
Society of Consulting Arborists (asca-consultants.org) certifies arborists who can determine the health and needs of a tree and make recommendations.