Prepared by: Nikki Rose D. DapanasBS Environmental Science III

Prof. Magdalyna Dulay

Terrestrial Decompositio

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Chapter 7: Terrestrial DecompositionTypes of Processes in DecompositionLeaching of LitterLitter FragmentationChemical Alteration

Course Outline:

Chapter 7: Terrestrial DecompositionTemporal and Spatial Heterogeneity Decomposition

Temporal PatternSpatial Pattern

Course Outline:

Chapter 7: Terrestrial DecompositionFactors Controlling Decomposition

Physical EnvironmentSubstrate Quality & Quantity

Microbial Community

Course Outline:

Chapter 7: Terrestrial Decomposition

Decomposition at the Ecosystem ScaleAnaerobic Heterotrophic Respiration

Course Outline:

Decomposition breaks down dead organic matter, releasing carbon to the atmosphere and nutrients in forms that can be used for plant and microbial production.

Overiew:

This chapter describes the key controls over decomposition and soil organic matter accumulation by ecosystems.

Overiew:

Conversion of dead OM into CO2 & inorganic nutrients

Decomposition…

Physical & Chemical breakdown of detritus

Decomposition…

LeachingFragmentation

Chemical Alteration

Types Of Processes

Removes soluble materials from decomposing organic material by water transfers.

Leaching…

Physical process by w/c mineral ions & small water-soluble org. cpd. Dissolved in water & move through the soils.

Leaching…

Soil animalsBreaks large pieces of organic matter into smaller ones

provide a food source for soil animals

create fresh surfaces for microbial colonization

Fragmentation…

dead organic matter is primarily a consequence of the activity of bacteria and fungi

occur spontaneously in the soil without microbial mediation

Chemical Alteration…

Fungimain initial decomposers of terrestrial dead plant material

80 to 90% of the total decomposer biomass & respiration

Chemical Alteration…

Bacteriasmall size & large surface to volume ratio of bacteria enable them to absorb soluble substrates rapidly & to grow & divide quickly in substrate-rich zones

lysing & breaking down live & dead bacterial & fungal cells

Chemical Alteration…

Litter & animal residues are gradually decomposed until their original identity is no longer recognizable

Soil Organic Matter…

Temporal patternThe predominant controls over decomposition change with time.

In seasonal environments, microbial respiration often occurs over a longer time period.

Temporal and Spatial…

Spatial PatternMost decomposition occurs near the soil surface, where litter inputs are concentrated

Decomposition rate is spatially heterogeneous at several scales.

Temporal and Spatial…

Physical EnvironmentTemperature MoistureSoil Properties

Soil Disturbance

Factors Controlling Decomposition…

affects decompositionDirectly promoting microbial activity

indirectly by altering soil moisture and the quantity & quality of organic matter inputs to the soil.

Temperature…

Carbon accumulation is greatest in wet soils because decomposition is more restricted by high soil moisture

Moisture…

Sufficient oxygen is available

Decomposers (plant) are most productive under warm moist conditions.

Moisture…

decomposition occurs more rapidly in neutral than in acidic soils due to a variety of interacting factors.

Soil Properties…

increases decomposition by promoting aeration

exposing new surfaces to microbial attack.

Soil Disturbance…

Litter

Substrate Quality and Quantity…

Soil Organic Matter

Substrate Quality and Quantity…

Microbial Community…

HUMUS..

Decomposition at the Ecosystem Scale…

Decomposition in anaerobic environments occurs slowly and produces energy inefficiently.

Anaerobic Heterotrophic Respiration…

God Speed

Thank You For Listening…