Microorganisms in Terrestrial Ecosystem

mineral oil

contains less than 20% organic carbon

most of Earth's soils

organic soil

posesses at least 20% organic carbon

retains nutrients

hold water (plant use)

maintains soil structure

Surfaces

Water (-- moisture)

Thin water films-- oxygen at high level+easily replenish

Depends on

rainfall

particle size

drainage

temperature

varies depend on

depth

latitude & altitude

Acidity&Allkalinity

usually pH 4-8.5

influenced by

microbial metabolic activity

time of the year

climate

previous cropping hysory

Soil atmosphere

well drained soil-- well aerated

influenced by soil particle size

depth

Decomposers

Mutualists

Pathogens

Litotrophs or chemoautotrophs

endomycorrhizae

fungi that enter the root hairs

ectomycorrhizae

fungi that reman extracellular, forming a sheath of interconnecting filaments around the root

functions

mineralizing nutrients

food source

subsurface zones

shallow subsurfaces

coal, kerogen, oil 7 gas containing region

methanogenic zones

make up one-third of biomass on Earth

stimulate growth

convert ammonium and nitrate to biomass

nitrogen saturation point

point beyond which any nitrogen added to soil won't be incorporated into organic matter and will remain in mobile form

differs than in open ocean

plants rather than microbes account for most primary production

plants or insects released degradative enzymes do not rapidly diffuse away

Bacteria

Aerobic

Anaerobic

Filamentous

epiphytes

microbes live on the surface of plants

endophytes

microbes that colonize internal plant tissues

source of nutrients, creating microbial loop

synthesis & degradation of organic matter

promotion of plant growth

associative nitrogen fixation

Decomposers

Mutualists

Pathogens/parasites

Ectomycorrhizae (ECM)

formed by ascomycete&basidomycete fungi

transfer essential nutrients (phosphorus/nitrigen) to roots

Arbuscular Mycorrhizae (AM)

transfer phosphorus to roots

provides ammonium to host

can increase plant's competiveness