Impact of Climate Change on Plant-Associated Fungi
85
2 Relation Between Climate Change and Diversity of Soil
Fungi
Fungi are main constituents of global ecosystems. They convert the hard digested
organic material into forms that other organisms can use. Fungal hyphae physically
bind soil particles together, causing stable aggregates that increase water infiltration
and soil water holding capacity. Soil fungi can be grouped into three general functional groups based on how they acquire their energy as follows (https://www.nrcs.
usda.gov/wps/portal/nrcs/detailfull/?cid=nrcs142p2_053864):
(i) Decomposers (saprophytic fungi) convert the dead organic material into fungal
biomass, carbon dioxide (CO 2 ), and small molecules, such as organic acids.
These fungi generally consume complex substrates, such as the cellulose and
lignin in wood and are essential in decomposing the carbon ring structures in
some pollutants. They are important for immobilizing, or retaining, nutrients
in the soil. Also many of the secondary metabolites of these fungi are organic
acids, which increase the accumulation of humic-acid rich organic matters that
are resistant to degradation and stay in the soil for hundreds of years.
(ii) Mutualists (mycorrhizal fungi) colonize plant roots, solubilize phosphorus and
deliver phosphorus, nitrogen, micronutrients, and water to the plant. One major
group of mycorrhizae, the ectomycorrhizae grow on the surface layers of the
roots and are commonly associated with trees. The second major group of
mycorrhizae is the endomycorrhizae that grow within the root cells and associated with grasses, row crops, vegetables, and shrubs. Arbuscular mycorrhizal
(AMF) is a type of endomycorrhizal fungi.
(iii) Pathogens are parasites that reduce production and result in death when they
colonize roots of plants such as Verticillium, Pythium, and Rhizoctonia, leading
to major economic losses in agriculture each year [3].
While it is difficult to study the variations in fungal activity and growth within
soil ecosystems as the mycelia are hidden below ground, it is easy to anticipate that
arbuscular ectomycorrhizal, endomycorrhizal fungi and saprotroph fungi with different nutritional needs are affected differently by changing the climate. For example, saprotrophs may be directly affected by the abiotic change, but mycorrhizal
fungi will be affected not only directly but also indirectly by effects on the host
plants. As a result, modifications in the activity and growth period of fungal mycelia
prompted by climate variation may have broad-scale changes on the carbon cycle of
soil ecosystems.
85
2 Relation Between Climate Change and Diversity of Soil
Fungi
Fungi are main constituents of global ecosystems. They convert the hard digested
organic material into forms that other organisms can use. Fungal hyphae physically
bind soil particles together, causing stable aggregates that increase water infiltration
and soil water holding capacity. Soil fungi can be grouped into three general functional groups based on how they acquire their energy as follows (https://www.nrcs.
usda.gov/wps/portal/nrcs/detailfull/?cid=nrcs142p2_053864):
(i) Decomposers (saprophytic fungi) convert the dead organic material into fungal
biomass, carbon dioxide (CO 2 ), and small molecules, such as organic acids.
These fungi generally consume complex substrates, such as the cellulose and
lignin in wood and are essential in decomposing the carbon ring structures in
some pollutants. They are important for immobilizing, or retaining, nutrients
in the soil. Also many of the secondary metabolites of these fungi are organic
acids, which increase the accumulation of humic-acid rich organic matters that
are resistant to degradation and stay in the soil for hundreds of years.
(ii) Mutualists (mycorrhizal fungi) colonize plant roots, solubilize phosphorus and
deliver phosphorus, nitrogen, micronutrients, and water to the plant. One major
group of mycorrhizae, the ectomycorrhizae grow on the surface layers of the
roots and are commonly associated with trees. The second major group of
mycorrhizae is the endomycorrhizae that grow within the root cells and associated with grasses, row crops, vegetables, and shrubs. Arbuscular mycorrhizal
(AMF) is a type of endomycorrhizal fungi.
(iii) Pathogens are parasites that reduce production and result in death when they
colonize roots of plants such as Verticillium, Pythium, and Rhizoctonia, leading
to major economic losses in agriculture each year [3].
While it is difficult to study the variations in fungal activity and growth within
soil ecosystems as the mycelia are hidden below ground, it is easy to anticipate that
arbuscular ectomycorrhizal, endomycorrhizal fungi and saprotroph fungi with different nutritional needs are affected differently by changing the climate. For example, saprotrophs may be directly affected by the abiotic change, but mycorrhizal
fungi will be affected not only directly but also indirectly by effects on the host
plants. As a result, modifications in the activity and growth period of fungal mycelia
prompted by climate variation may have broad-scale changes on the carbon cycle of
soil ecosystems.