Thursdays Ecology

Bur Oak

Quercus macrocarpa

Quercus macrocarpa, aka Bur Oak or Savanna Oak, is the most widely distributed and northern reaching oak tree. This is most likely due to its ability to withstand a wide range of harsh conditions and is known to be on the most drought resistant oaks. This relatively fast growing oak is also resistant to Oak Wilt, and is a good Urban tree because of its resistance to air pollution and car exhaust.

Usually wider than tall, the crown is open wide sitting on a massive trunk supporting the heavy horizontal limbs, reaching heights ~60-80 ft. The large, dark green leaves create dappled shade below and the large acorns typically develop in the fall. This is a masting species, with optimum seed bearing years at 75-150. Prune only in the later winter to remove dead, damaged, or rubbing branches. Avoid pruning more than 1/3 of the tree.

These trees prove to be a biodiversity hub with the number of songbirds, ground birds, mammals, butterflies (Edwards' Hairstreak and Horace's Duskywing Butterfly), and insects that rely on this tree species for food, shelter, and nesting. Its important to remember that leaf litter is vital to these communities and should be left in place. Raking and removing these leaves will only cause more harm to the damaged ecosystem, and as a result the garden, or green spaces nearby.

Considering the urban setting of Houston, or any city in this Ecoregion, a good location to install a series of Bur Oaks is at parks, where their large beautiful shape, their wildlife attraction, and their adaptability to soil and weather conditions can thrive without people's input.

As this Oak grows it's Ecosystem Services will increase and eventually stabilize at:

~94 lbs CO2 Sequestered / tree / yr

~407 lbs CO2 Total Storage

~1740 gals Floodwater Mitigation / yr

~0.9 lbs PM2.5 Air Pollutant Removal / yr

sources: USFS, Lady Bird Johnson Wildlife Center, Houston Wilderness