Largely invisible and often overseen, fungi and other microscopic organisms are highly abundant in soils across the world, and play a fundamental in maintaining the biodiversity and nutrient balances in their ecosystem.
Fungi, although visible in the form of fruiting bodies, or toadstools, during certain times, are largely invisible, existing as microbial threads in the soil. It is estimated that there are some 3.8 million species of fungi, only a fraction of which have been formally described and identified. These organisms are incredibly abundant in soils around the world, an are a key component of biological nutrient cycling, as they break down organic matter, releasing key nutrients and compounds from dead bodies. Fungi are found in a variety of areas such as rainforest, woodland, grasslands and even rocky substrates (in the form of lichens) but are most abundant in open areas such as grasslands and Savannah, where they are important in helping poorer soil uptake nutrients.
In the Amazon rainforest for example, fungi are surprisingly abundant and varied. For example, a teaspoon of rainforest soil is estimated to contain around 1800 species of microscopic organisms (according to a study carried out by Dr Camila Duarte of Germany), at least 400 of which are fungi. These fungi are so diverse and they occupy a variety of niches in the forest, such as lichen (a symbiotic relationship between fungi and microscopic plants), some living commensally in the roots of plants and some as plant pathogens and parasites. Each and every one of these plays a significant role on the forest floor, breaking down organic matter and releasing nutrients back into the soil, to be used by plants and animals.
In this sense, the sheer diversity of fungi in the soil means that it is essential to consider this hidden diversity in conservation efforts, particularly in such fragile ecosystems as the Amazon rainforests. Due to their inconspicuous nature fungi are often overlooked in biological surveys, but they are key for nutrient cycling and also act as carbon sinks, absorbing carbon dioxide from dead organisms.
Some species are also edible, and are a source of medicine, indeed fungal compounds are being considered as new antibiotic sources in the light of antibiotic resistance. On the other hand, some fungi are considerable pests to crops, while others are disease-causing pathogens which cause disease in humans and animals. There is much to learn about soil fungal diversity, in order to incorporate these organisms into conservation efforts, and to help maintain biodiversity.