The Relationship Between Mycorrhiza & Trees | Home Guides | SF Gate
Mycorrhizal partnerships are symbiotic relationships between plants and In each case there is cell-to-cell contact between the plant and the fungus, The cep or penny bun (Boletus edulis) tends to associate with oak, and is also a delicacy. This is the familiar toadstool of storybooks, with its vivid red cap and white spots. White oaks suppress seedling recruitment of loblolly pines via belowground . Ectomycorrhizal diversity of oak forests in the Sierra Madre Oriental, Mexico 42 .. More recently, the relationship between aboveground and belowground. However, the mycorrhiza fungus performs essential functions in the soils, and they form symbiotic relationships with trees through the tree's root system. It's estimated that more than 80 percent of higher plant species develop symbiotic relationships with mycorrhizal fungi.
Oak trees live in association with usually two kinds of fungi called mycorrhiza. These fungi live on or in their roots. The fungi also extend beyond the oak trees roots to collect nutrients and water for themselves and the oak trees as well as other plants hooked up to this mycorrhizal grid. One kind of this mycorrhizal fungi is called Ectomycorrhiza, as these live on the outside of the oak root, and you can see them with the naked eye.
They extract nutrients from the oak leaf litter, as they break it down, and share some of these nutrients with the oak tree. They live in the top four inches of soil under the canopy of the oak tree.
For someone who has never seen Ectomycorrhiza you might think it was dry rot, or the roots had knobs instead of root hairs. This kind lives inside the oaks roots and are microscopic.Mycorrhizae in Hindi/Urdu - Biology Crash Course #142
They live in the soil zone below the ectomycorrhizal fungi, from four inches below the soil surface to 20 feet down into the ground. What does the mycorrhizal fungi do? Oaks need these fungi to live; that is, oaks are obligately mycorrhizal. The association that oaks have with these types of mycorrhiza is called symbiotic. This is a relationship where each partner shares something it possesses with the other partner. In the case of the oak and the mycorrhizae mycorrhizas: The mycorrhizal fungi provide nutrients and water to the oak.
Mycorrhiza can be a thousand times more efficient than root hairs at extracting minerals and moisture. The fungi also protect the oak from diseases, that is, they are like the oak tree's immune system.
The fungi produce chemicals that inhibit pathogenic bacteria, fungi and herbivores. In return, the oak provides carbohydrates, food the fungi cannot make because they do not contain chlorophyll, Only green plants such as the oak contain chlorophyll, and can make food from the sun's energy. Oaks also bring up deep water that the fungus can't get to.
Another critical function of these fungi is erosion control. The tiny strands hyphae of the body of the fungus wrap around individual particles of sand or clay and, in addition produce a glue, that helps hold soil particles together, thereby controlling erosion.
Sharon Rose's photo is a good illustration see reference section, Rose, Sharon. These fungi form connections underground from oak tree to oak tree and to other plants in the community, thereby interconnecting most of the plants of the plant community. If one area of the forest has excess nutrition or moisture the fungi will attempt to balance the forest.
Oak trees have sideways roots and a few vertical tap roots. What happens if the mycorrhizal grid is disturbed? In California native ecosystems there are many more fungi in the soil than bacteria; the numbers are usually 10 fungi to 1 bacterium.
California oak trees and mycorrhiza
This is a critical point because, if the native ecosystem is broken down, such as when a disturbance occurs, and there is a mass invasion of alien plants, the numbers change. In these situations, where alien plants are now the dominant species, and there are more bacteria than there are fungi. This phenomenon is called an ecological switch. It is as if all the numbers are automatically changed, just as if a light switch is turned on or off.
The change in the ratio of fungi to bacteria demonstrates that the change in the ecosystem occurs from the microscopic level up to the level of the massive oak trees. This is very bad news for the oak tree because, remember, its immune system, its water, and its nutrients, depend upon the dominance and integrity of the fungi.
For example, think of a small section of oak woodland, a lovely hill covered with oaks and pines and their associated plants. Then imagine a soil disturbance, such as a caterpillar tractor climbing this hill, turning this way and that to avoid the trees.
The result is gashes of bare soil, where the associated plants were torn up. When the associated plants were torn up and the bare soil was exposed, the threads or hyphae of the mycorrhizal fungi that are attached to the roots of those plants were also broken. These threads are the body of the fungus. Within this body nutrients and water are held.
Guess what leaks out all over the ground and is now available for any enterprising weed to pick up? Yeah, nutrients and water. What do weeds dearly love? Lots of nutrients and water! Limited soil disturbance does occur naturally such as rodent activity, but this is very minor if the habitat is undisturbed, and has a healthy plant community.
When an area becomes disturbed and has an influx of alien species, usually lots of grasses certain rodent populations explode. How does ecological succession apply to mycorrhizal fungi? As the oak tree grows, different species of fungi live with it. Also, more species live with it as it grows. On an old oak tree, there may be species living in symbiosis with the oak.
California Native Oaks and Mycorrhiza
Also, as the season changes from winter to spring, for example, the dominant species of fungi living on the oak change. More water is tolerated when the oak tree is young because the species of fungi that live in association with the oak tolerate more water.
Remember, though, this relationship between the oak and the fungi is bases on stress. This means the fungi will only live with the oak if the oak is under slight water or nutrient stress. How does the plant community use mycorrhizal fungi? Oak trees need their associated plants to do their best, they do not do well alone, just as people cannot function as well alone, but need their family and friends.
The fungi also inhibit invasion by damaging fungi, and extend the life to root tips. Mycorrhizae release acids that break down substances that the plant cannot use without this help, and fix nitrogen from both the soils and atmosphere so that it is more available to the tree.
Mycorrhizal fungi produce hormones that encourage the production of new root tips, which aids both the tree and the fungi. Benefits to the Mycorrhiza The symbiotic relationship between mycorrhizae and trees benefits the fungi as well. Fungi cannot manufacture their own food due to lack of chlorophyll, a process that converts sunlight to energy used for producing sugars. Therefore, fungi must get this food from chlorophyll-producing plants. They do so by either penetrating the plant roots or forming a sheath around the root tips.
This energy allows the fungi to reproduce and form large networks within the soils. Professor Suzanne Simard of the University of British Columbia identified the "mother tree" concept, which suggests that the largest trees of the forest, or the mother trees, infect the new seedlings with mycorrhizae, providing a highway by which the mother tree can provide the seedling the nutrients it needs to survive. Trees under stress may receive carbon through underground pathways from nearby trees not experiencing stress.
Ectomycorrhizas There are essentially two ways in which mycorrhizae function.