Terrestrial Ecosystems

Soil

Composite of various surfaces, pore sizes, and components

What does soil influence?

\-Nutrient availability

\-Oxygen availability

\-Colonization by organisms

Peds

Mineral particles and organic matter held together by electrical chargers

Weathering

Breaking down rock into smaller peices

Process of soil formation

1. Newly exposed rock undergoes chemical weathering
2. Over time, broken rock will be colonized by microbes (accelerated by metabolic wastes)
3. Habitat is changes so larger, more complex organisms can colonize
4. Organic matter accumulates since primary production is greater than decomposition rates

What happens if decomposition is greater than primary production?

\-Low organic matter

\-Low fertility

\-Occurs in deserts

Rhizosphere

\-Areas on roots

\-Microbial communities

\-Synthesis and decomposition of organic matter

How is community structure influenced by microbes on rhizosphere?

\-Pathogenic members put chemicals into soil to decrease amount of pathogenic microbes

\-Symbiotic members encourage growth

Rhizobium

\-Symbiotic relationship in legume roots

\-Gall formation

\-Nitrogen fixation

Gall formation

Abnormal growth on plants for insects to use as homes for their egg/young

Fungi

\-Mycorrhizae in fungal roots

\-Include ecto and endomycorrhizae

Ectomycorrhizal

\-Form sheath around root

\-Hyphae acts as root hairs

Endomycorrhizae

Invade plant tissue and grow in plant roots

Epiphytes

\-Bacteria and fungi that grow in/on plant surface

\-Gives plant resistance to other pathogens