T1 T2 T7 T8

Entolomatoid

Rhodocyboid

/psathyrellaceae I /crepidotoid

/bolbitiaceae

/nolanea /inocephalus /entolomatoid /clitopilus /tricholomatoid /cortinarioid

Collybia — Clitocybe group /clavarioids Stephanospora sister clade to Volvariella unknown clade /pluteus /mycenaceae Lachnella — Calathella /agaricus

Laetisaria — Lyphophyllum /coprinellus /psathyrella /coprinopsis /crepidotus /tetrapyrgoid /conocyboid /bolbitioid /inocybe /psychedelia

/lichenomphalia

/hygrocybe I /hygrophoraceae

Tricholomataceae — Cantharellula umbonata Thelephora Pseudotomentella Scytinostroma Geastrum

Phanerochaete M M

Ganoderma

Sistotrema _

Hyphoderma ■

Porpomyces ■

Fomitopsis |

Cotylidia g

Cyclomyces g

Ceratobasidium g g

Multiclavula g g

Cystofilobasidiales g g

Urediniomycetes g

Ceratosebacina g

FIGURE 6.2 Phylogenetic relationships of Basidiomycota detected by PCR amplification, cloning, and sequencing of 95 10-g samples from Michigan agricultural soils (Lynch and Thorn, 2006, and unpublished data). The tree was formed by neighbor-joining analysis in PAUP* 4.0b (Swofford, 2002) of all environmental sequences together with all nonredundant reference sequences from GenBank, so that unknown sequences could be named by being placed in terminal clades together with

(number of clones analyzed) will be required to provide a meaningful estimate of the composition and diversity of the community. Even restricting our analyses to soil Basidiomycota, we have found as many as 9 genetic species (where these are defined as having less than 99% similarity over the 5' 650 bases of nuclear large subunit ribosomal DNA) among 12 clones taken from a single PCR of DNA from a 10-g sample of Michigan agricultural soil (Fig. 6.2; for more methods, see Chap. 4). A total of 241 genetic species were detected in 95 such samples from an 11.2-ha site, and the estimated total species richness for the site is 367, as many as all of the species of macromycetes (larger mushrooms) known from The Netherlands! Some taxa were found across a wide range of agronomic treatments, from corn-soybean-wheat rotation with regular tillage and inputs (T1) to never-tilled native meadow (T8), but the greatest diversity was found in the latter. Basidiomycete diversities in forested ecosystems are predicted to be much higher. So, whether in numbers, biomass, or ecological or biochemical activities, the fungi are important in most soils.

Eukaryotic algae are a polyphyletic group of organisms, derived from several separate lineages: plants (green and red algae and glaucophytes), excavates (euglenoids), cercozoans (chlorachniophytes), and the heterokonts and alveolates (brown algae, xanthophytes, chrysophytes, diatoms, haptophytes, cyryptomonads, apicomlexa, and dinoflagellates). Among these, a number of unicellular, colonial, and filamentous taxa represent an often overlooked component of the soil community. These algae may be locally very important in carbon fixation, soil binding, and nutrient transformations. Interactions and synergisms within the microbial community are probably essential in soil functions, including decomposition, aggregation, and nutrient release from insoluble reserves, all functions in which fungi and algae play a central role.

classification, characteristics, and ecological roles in soil

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