Looking Deeply into Deer Park Plants: Meet the Oak Trees
Native Plant Communities
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Caring for and Continuing our Oak Tree Community
Plant communities are like human communities
Like people, California native plants need to live in a community to survive. This is very important in Southern California where there are many stresses for a plant. The inland summer temperatures can be very high and plants may need to survive 8-9 of the hottest, driest months without any water. Plants also have to endure fire and freezing temperatures.
|Like people, oak trees do not survive well alone||
By understanding one native plant community, we can understand a lot about many of the plant communities. Looking at the relationship of oak trees to their environmental conditions is a good way to learn about how to cultivate healthy plants at Deer Park. Oak trees need their associated plants to thrive and do not do well alone or among plants that cannot nourish them, just as people cannot function as well alone, but need their family and friends.
Special fungi—Mycorrhiza—interconnects the plants within the community
They form connections underground from oak tree to oak tree and to other plants in the community, thereby interconnecting most of the plants within the plant community. If one area of the forest has excess nutrition or moisture the fungi will balance the forest and share the nutrients.
The connection of many plants underground with these fungi is called a ‘mycorrhizal grid’ and because plants can use this grid to share water and nutrients, they can survive great stresses, like drought. But, without this underground grid, native plants, like oaks, cannot live.
|Fungi and trees sustain each other||
The mycorrhiza and the oak tree nourish each other. The fungi provide nutrients and water to the oak. They can be more than 1,000 times more efficient at extracting water and minerals from the ground that roots. They also protect the tree roots from diseases and act like the oak trees’ immune system. In an old oak tree, there can be up to 250 species of mycorrhiza living with and protecting the oak roots.
In return, the oak trees provide carbohydrates for the fungi, food the fungi cannot make because they do not contain chlorophyll which allows the trees to make food from the sun’s energy.
Protecting mycorrhiza, protecting the oaks
In California’s native ecosystem, there are far more fungi in the soil than bacteria. Many non-native plants introduce large amounts of bacteria into the soil and this can disturb or destroy the plant community needed to sustain the oaks.
There are other fungal friends associated with the oaks; some live in the leaves, some in stems, some in the trunk. Like mycorrhiza, they share resources to protect the tree and themselves.
|We can take care of our oaks||
The ‘root protection zone’ is the most important area for an oak. This is an area that extend from the tree to beyond the drip line. Oak trees survive on lateral roots and the top six inches of soil under the drip line is the most sensitive to disturbances. No non-native plants or grasses should be planted in this area.
Since the mycorrhiza live close to the surface as well, we should not drive on or park cars or otherwise disturb or compact the soil in this area if we want our trees to stay healthy. Oak leaf mulch should be left in place as it nourishes and protects the root zone.
Fertilizers, insecticides, or herbicides are very damaging for fungi and can cause it to disconnect from the grid, weakening the tree. There are many plants that are ‘allies’ of oak trees and can be planted under or near oak trees. These include coffeeberry, gooseberry, ceanothus or native lilac, manzanita, honeysuckle. As a community of plants, they can better resist the invasion of non-native species that undermine the health of the community.
Continuation of Oak Trees and the rare Englemann oak
We would like to grow even more oak trees from acorns from Deer Park Oaks especially our rare Englemann oaks. All oak trees are wonderful but the rare Engelmann oak species is probably the most imperiled of all oak trees and are one of the most endangered natural plant communities in California.