Oaks Are A Keystone Species

A keystone is the last piece of the arch that, when placed, holds the whole thing together.  Keystone species are species that hold their ecosystem together.  Without them, the other plants and animals can’t survive. 

What Makes Oaks Key? 

Oaks (Quercus) dominate the North American forests.  Out of 435 species of oak, sixty percent live in North America alone.  Over the last 45 million years, oaks have developed to live in every climate niche in the United States and Mexico. 

How Do Oaks Support Other Species? 

Oaks provide food, places to live, medicine, and shade.  Oak woodlands provide many different kinds of habitat. 

Food 

Oak trees produce around 140 pounds of acorns a year.  People used these acorns as a major food source, eating 700-1000 pounds of acorns a year.  Indigenous people in North America actively managed oak forests for maximum acorn production.  Individual trees were passed down through families. 

Shelter 

Oak trees support more life than any other tree.  Just one tree can host 532 species of caterpillars.  In addition, it can shelter 147 species of birds, 120 species of mammals, 60 species of reptiles and amphibians, and 280 species of insects.  They host colonies of plants that need other plants to grow on, including mosses, ferns, lichens, and bromeliads.  The leaves feed moth and butterfly larvae.   

Shade 

You might not think shade is that important until you work outside without any on a hot day.  Oaks provide shade for livestock in a pasture, for workers to sit in during lunch, and for animals who need to cool off.  In a yard, a big oak can shade your house during the hot months and lower your electricity bill significantly. 

Dollar Value of Oaks 

Homes with oak trees in their yard or nearby sell for 7-30 percent more than homes without oak trees.  In addition, oak woodlands help mitigate the effects of fire, floods, erosion, and air pollution.  They provide oxygen and sequester carbon.  Areas in town with lots of oaks and other trees are cooler in the summer than areas without trees.   

Oak Decline A Threat 

Oakes, and especially oaks in woodlands, are declining.  Some of this is due to habitat fragmentation.  Individual oaks are protected in many towns against being cut, but as subdivisions and other construction goes in, oak woodlands are lost.  Some oaks species, especially white oaks, grow slowly.  They may only produce a decent crop of acorns once every five years.   

Oaks are also being crowded out of woodlands because of the lack of fire.  Fires clear brush, burn saplings and seedlings, and keep other species of trees in their proper place in the forest.  Properly done, prescribed fires do this for oak forests.  Without these things happening, oaks get crowded out and decline. 

What You Can Do To Help 

We can help control oak decline by reducing the stressors on oak trees.  Here are some ideas. 

Removing invasive vines from trees 

Invasive vines such as kudzu will eventually strangle the tree they are growing on.  Both the weight of the vine and vines blocking sunlight, water, and nutrients from reaching the tree are deadly.   Remove any vines growing on your oak trees to keep this from happening. 

Avoiding damage to tree limbs, trunk, and roots 

Damage to the tree is cumulative.  Hitting the roots with a mower, cutting the tree with a string trimmer, and damaging the bark all add up.  Make sure that you consider the roots of the tree when digging or placing buildings such as sheds over them. 

Monitoring trees for insect pests and fungal and bacterial infections 

While some insect activity is desirable, insect pests can cause problems.  Monitor your oaks for those pests and for diseases.  Frequently, pests and diseases attack oaks that are already having problems. 

Pruning damaged/diseased limbs 

Pruning damaged and diseased limbs needs to be done as soon as possible.  However, oak wilt can enter the tree at cuts made by pruning or other injuries.  If oak wilt is a problem in your area, we recommend not pruning your tree from February to July, when the vectors of oak wilt are the most active. 

Mulching around the base of trees to protect roots 

A layer of three inches of hardwood mulch in a donut shape around the trunk protects roots from damage caused by mowers, string trimmers, and other impacts.  Start the layer about a foot from the trunk and cover the area as far out as the dripline, but especially the area where the roots are shallow and easily damaged.  Mulch retards the growth of weeds and keeps the soil moisture and soil temperature from wildly swinging. 

Watering trees during dry spells 

Oak trees use water to carry water and nutrients from the roots to the crown.  They also use water to cool themselves.  During a dry spell, water deeply once every two weeks or so to make sure the oaks have enough water for their needs.  Dry, hot oaks are likely to suffer and can even die.  In the winter, water deeply once a month or so. 

Limiting pesticide use 

Using a lot of pesticides is not good for anything.  However, using a lot of lawn pesticides, especially post emergent broad weed killers, can make your tree sick.  Trees are broad leaf plants, so weed killers, especially in weed and feed products, can cause problems. 

Consulting with local forestry experts and ISA Certified Arborists for advice and assistance on tree-related issues 

If your tree needs pruning for safety reasons or due to disease, consult with your area’s urban forester or an ISA Certified Arborist.  Do not use “tree trimmers” or the guys that knock on your door offering to trim your tree.  ISA Certified Arborists have lots of education and practical experience, so they can help your tree stay healthy.  They also know how to treat many tree diseases with the least harm to the environment. 

Picking An Oak Tree To Plant 

Oak trees are roughly divided into two categories, white oaks and red oaks.  Red oaks have bristle-tipped lobes on their leaves and acorns that take two years to mature.  White oaks have rounded lobes on their leaves or large regular teeth and acorns that mature in one year.  There are many species in each category and each species grows best in specific areas of the country.  We can help you find the oak species that works best in your area.  Here are some examples of each type of oak tree. 

White Oak 

White oak trees grow to 80-100 feet and provides shelter for many animals.  You can use them for shade in a hot climate. 

Chestnut oak 

Chestnut oaks grow to be 50-60 feet tall and have shiny, glossy leaves.  They turn red and yellow in the fall.  

Red Oak 

Red oak trees have leaves that are green in the spring and summer and turn brilliant red in the fall.  They make a nice specimen tree because of their tall straight growth pattern. 

Black Oak 

Black oak trees can grow to 50-80 feet with a broad crown.  They are often used in forest restoration. 

Pin oak 

Pin oaks are native to an area from New England to North Carolina and west to Kansas and Oklahoma.  They turn brilliant red in the fall.  Pin oaks grow faster than most oaks.  They tolerate damp conditions and like to grow next to streams, lakes, and rivers. 

Call Us 

TN Nursery prides itself on our ability to help people choose the right plant for their space.  Simply call 931.692.7325 and let us guide you to your next oak tree.