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Oak tree services
Oak tree services
Oak trees provide food for woodpeckers, jays, rodents, bark beetles, snails, caterpillars, gall wasps, lichens, and fungi.
Oaks provide shelter for bee hives, tree frogs, nesting birds, insects, molluscs, rats and squirrels.
Oaks provide important air conditioning by cooling and filtering the air.
Oak "apples" are made by wasp larvae that turn on oak cell DNA. The oak cells grow to make them a little home and feed them with nutrients until they hatch as adult wasps.
Oak tree varieties
Oak tree varieties
California has two main types of oak tree: deciduous robles oaks and evergreen encino oaks. If you focus on their key characteristics, you don't have to learn the features of all 22 species found in the area, you just need to focus on two.
Robles oaks, the oaks of the wide valleys
Robles oaks, the oaks of the wide valleys
Valley Oak in Conejo Valley at the Oaks Mall, California. Hannah Robinson.
Valley Oak Quercus lobata is the Robles type of oak which many people in California will have noticed for its gnarly twisted old branches.
Valley Oak is less drought-resistant than chaparral oaks due to having large leaves that lose water readily and are re-grown every year. It is found near rivers along the coast, and across the Central Valley of California. You can also find Valley Oaks in shopping centers, parking lots, backyards, and along city barancas, where the trees are clinging on to remnants of their original habitat.
Valley Oak is the largest oak in the region, and is easily recognized by its great size and its large, flat, lobed leaves. Lobed means rounded pods on each leaf, like lots of ear lobes. This tree is deciduous, which means it drops its leaves in winter, unlike the chaparral oaks.
Encino oaks, the oaks of the chaparral
Encino oaks, the oaks of the chaparral
Coast Live Oak in Harmon Canyon, California. Hannah Robinson
Chaparral oaks are the Encino type of oak tree. Encinos are evergreens, which is why they are also called "live oaks" because they are green in winter. They are fully adapted to the very dry summers of the chaparral.
Chaparral oaks have dark small leathery leaves that keep water in and are often cupped and spiked. They may have furry undersides. The fur and cups make a moist microclimate next to the stomata (leaf mouths) to reduce water loss and keep water in for photosynthesis. The spikes prevent browsing by deer and other herbivores, a necessary adaptation to keep alive, as these trees grow very slowly in the summer-time due to a lack of water.
The commonest encino oak in coastal Chaparral is the majestic Coast Live Oak Quercus agrifolia which can grow almost as large as the Valley Oak.
Another encino oak in the California chaparral is the smaller, bushy California or Inland Scrub Oak Quercus berberidifolia. This shrubby tree is found in both coastal and inland areas. Like the Coast Live Oak, some of its leaves are cupped and wooly to conserve moisture, it has prickles and it is an evergreen.
Check out the oaks in your own area by going on a desktop to https://www.inaturalist.org/observations then entering your county and the word "oak." Then tap "species" to get a grid. You do not need to register. You can search for any organism this way.
Or open the page below for Ventura County which has 22 wild oak species, organized commonest to least common. Tap to explore each.
In addition to iNaturalist, Calflora has details of each type of oak tree at a more academic level. Registration is not required. Search by tapping on https://www.calflora.org/search and entering the plant you are interested in.
The pages below are linked to Calflora so you don't need to search.
Valley Oak has a Central Valley and more northern distribution in addition to the coastal areas.
California Live Oak has a more coastal, chaparral distribution and can withstand drought.
California or Inland Scrub Oak has a more southern and coastal distribution and can withstand more heat.
From the desk of Hannah Robinson
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