The ecological role of mycorrhizal fungi
We generally know more about the ecology of the organisms (such as plants and animals) visible in the soil in the forest, while the tiny creatures in the soil pay less attention.
The amount of microorganisms and types in the soil is far more than the “higher organisms” we can see on the land with the naked eye. Fungi in soil are an important part of terrestrial ecosystems. Fungi not only play the role of “decomposer”, but also have many other important roles. Mycorrhizal fungi is one example.
Mycorrhizal fungi (mycorrhizal fungi) is the fungus that is ubiquitous in the soil and can grow with the root system of the plant to form a symbiotic relationship. “Symbiosis” with plants means that it will not harm to the health of the host plant, but is also reciprocity and prosperity.
Symbiotic mycorrhizal fungi obtain carbohydrates and other nutrients from plant tissue cells, and mycorrhizal fungi also increase the area of plant roots in contact with soil, increase the plant’s ability to absorb water and nutrients, and thus promote plant growth.
According to the combination of fungi and roots, mycorrhizal fungi can be divided into three categories: ectomycorrhizae, endomycorrhizae and ectendomycorrhiae.
Mycorrhizal fungi are generally known to have the following ecological benefits:
1. Promote plant growth:
The parts of plants that absorb nutrients and water mainly lie in the root hairs of new roots; however, mycorrhizal fungal infections promote root hair production. Therefore, mycorrhizal fungi not only have the effect of promoting nutrient and water absorption, but also have the ability to improve soil structure, increase soil aeration and water retention, and promote plant growth and development. The results of the study confirmed that the mycorrhizal fungi and seedlings symbiotic, have a significant effect on seedling growth above ground or below ground. The growth rate of seedlings inoculated with mycorrhizal fungi is several times higher than that of uninoculated seedlings.
2. Fix nutrients in the soil:
Plant litter contains esters and phenols, not only toxic to plants and fungi, but also inhibits the decomposition of litter. Mycorrhizal fungi can secrete all kinds of enzymes and convert this toxic substance that is not easy to decompose into available nutrients. In addition, mycorrhizal fungi form a large number of hyphae through their network growth in the soil and store nutrients in the mycelium, “fixing” nutrients and moisture in the soil in the ecosystem, and these hyphae die After slow decomposition, it will provide nutrients to the plant again, thereby improving the efficiency of the ecosystem’s use of resources.
3. The fruiting bodies and mycelium of mycorrhizal fungi are food for other organisms and become a member of the soil food web:
The fruiting bodies or hyphae of some mycorrhizal fungi are food for arthropods in the soil, some small mammals and some birds. On the one hand, these fungi as animal food sources play a role in maintaining the diversity of species in the ecosystem. On the other hand, the biomass of mycorrhizal fungi directly enters the soil food web through the animals and thus accelerates the material circulation. A few of the fruiting body species are food ingredients in some traditional human cultures, such as Boletus, Truffle, Russula, etc. The mushroom fungus afforestation project is to encourage farmers to participate in planning and take care of the forest.
4. Regulate the allocation of resources in the ecosystem and maintain species diversity in the ecosystem:
In natural terrestrial ecosystems, most plants have symbiotic mycorrhizal fungi, and some mycorrhizal fungi are not very specific and can symbiosis with different hosts at the same time. Therefore, in an undisturbed forest ecosystem, the hyphae of the infected plant ’s roots growing outward can further infect the roots of other plants, so that some of the system can be separated by the mycelium of different mycorrhizal fungi. Unrelated plants are connected together, and materials and information are exchanged through the mycelial network or mycelium bridge or mycelium connection between plant roots. Ecologists have noticed this combination in the ecosystem, and call these plants combined by mycelium “GUILDS”, just like the Internet between people, Plants also have a way to communicate with each other. It has been proved that the plants in the “dependent plant group” can use mycelium as a channel to transfer nutrients between the plants in two directions, thus affecting the resource allocation in the ecosystem.
Reference：
- 台灣林業研究專訊 Vol.18, No.6, p.15-18, 2011
- 趙之偉. (1999) 菌根真菌在陸地生態系統中的作用. 生物多樣性, 07(3), 240-244.
- Gianinazzi, Silvio & Gollotte, Armelle & Binet, Marie-Noëlle & van Tuinen, Diederik & Redecker, Dirk & Wipf, Daniel. (2010). Agroecology: The key role of arbuscular mycorrhizas in ecosystem services. Mycorrhiza. 20. 519-30. 10.1007/s00572-010-0333-3.