Decomposition and Nutrient Cycling

downstream, other arthropods

(filtering and gathering collectors) filter from the water fine particles and fecal material from the shredders

aquatic arthropods

(shredders) fragment organic particles, eating bacteria and fungi on the particles

types of microbial decomposers

1. bacteria 2. fungi

Zones in open-water ecosystem

1. epilimnion (surface water) 2. thermocline 3. hypolimnion (deep water)

water depth and tidal cycle

1. flushes salts and other toxins out of the marshes 2. brings in nutrients from the coastal waters through tidal subsidy 3. replaces oxygen-depleted waters within the surface sediments with oxygenated water

decomposition includes

1. leaching 2. fragmentation 3. changes in physical and chemical structure 4. ingestion 5. excretion of waste

groups classified by body width

1. microfauna/flora 2. mesofauna 3. macrofauna 4. megafauna

How can organisms change spiral distance

1. organisms that shred and fragment material open the spiral and more things flow down stream 2. organisms that physically store dead organic matter tighten the spiral

Examples of microbivores

1. protists (amoebas) 2. springtails 3. nematodes 4. beetle larve (grubs) 5. mites smaller feed on bacteria and fungal hyphae larger forms feed on both microflora and detritus

Speed of downstream movement depends on

1. rate of water flow 2. physical features that "catch" organic material

events along the western margins of continents

1. surface currents flow along the coastline to the equator 2. these surface waters are pushed offshore by the Coriolis effect 3. this leads to the transportation of deeper, nutrient-rich water to the surface

Spiraling and Distance

1. the longer the distance, the more open the spiral 2. the shorter the distance, the tighter the spiral

physical features that "catch" organic material

1. wood detritus 2. debris caught in pools 3. in sediments 4. in patches of vegetation

leaf packs

Areas of active deposition and accumulation of leaf litter

soil microbial loop

Describes this process of - plants supplementing carbon to microbial decomposers in the rhizosphere - enhanced decomposition of soil organic material - predator remobilization of mineral nutrients for plant uptake

surface water in temperate and polar zones

In autumn 1. the amount of solar radiation decreases 2. surfaces water temperature declines 3. as the water temp of the epilimnion approaches that of the hypolimnion the thermocline breaks down and mixing occurs

dissolved organic matter (DOM)

Organic material dissolved in ocean water

microbial decomposers

Secrete enzymes into tissues to break down organic compounds then absorb them

nutrient cycling

The circulation of chemicals necessary for life, from the environment (mostly from soil and water) through organisms and back to the environment.

soil organic matter

a complex mixture of partially and completely decomposed detritus- humus embedded in the soil matrix

nutrient spiraling

a representation of nutrient dynamics in streams when downstream displacement of organisms and materials, are better represented by a spiral than a cycle

Decomposition involves

a succession of microbial decomposers until the organic material is mineralized

Vertical zones of production and deposition

appear in forrest and in oceans most ecosystems have a vertical separation between the zones of production and decomposition

flowing water ecosystem

aquatic fungi colonize particulate matter 1. aquatic arthropods 2. downstream, other arthopods 3. grazers and scrappers 4. algae

Nutrients for Cycling

are usually found in the atmosphere or rocks 1. nutrients enter the soil or water and are taken up by autotrophs 2. nutrients stored in organisms (living tissue 3. when organisms lose parts or die, nutrients are returned to soil or sediments as dead organic matter and enter the detrital food chain

Quantity and quality of organic matter

as a food source for decomposers it directly affects 1. the rate of decomposition 2. the rate of nitrogen mineralization

Mineralization greater than immobilization

as decomposition proceeds, carbon quality declines and net release of nitrogen to the soil or water

Changes in C/N ratio

as plant material is consumed, nitrogen is immobilized to meet the demands of the decomposers (ratio declines)

populations fluctuate

as protist and nematode pop decline, their readily decomposable tissues enter the detrital food chain

Anaerobic bacteria

bacteria that do not require oxygen to survive

mesofauna

between 100um and 2mm includes mites, potworms, and springtails living in soil air spaces

Macro and Megafauna

between 2 and 20 mm (macro) over 20mm (mega) includes terrestrial millipedes, earth worms, and sails

limits to the rate of internal cycling

cycling nutrients within an ecosystem relies on photosynthesis and decomposition 1. primary productivity determines the rate of nutrient uptake 2. decomposition determines the net mineralization rate

Nitrogen Dynamics

depends on the initial concentration in the leaf litter if concentration is high mineralization may exceed mobilization from the beginning and N concentration will not increase about 100%

Ciliates and Zooplankton

excrete nutrients into the water as exudates and fecal pellets when there is lots of food zooplankton consume more than they need and excreting over half or more as fecal pellets

Excess Nitrogen

excreted as ammonia so it can be taken up by plant roots

grazer and scrappers

feed on algae, bacteria, fungi, and organic matter on rocks

Microbivores

feed on bacteria and fungi

Equatorial currents

flow west 1. they are deflected to the right N of the equator and left S of the equator 2. where this occurs, subsurface water is transported vertically 3. cold waters, rich in nutrients, come to surface

humus

forms as decomposition and mineralization takes place and litter degrades

Bacteria Growth

get nutrients by breaking down soil organic matter limited by nutrient availability

carbon compounds

glucose and smile sugars- high quality source of energy cellulose and hemicellulose- moderate quality source lignin- low quality source

Assimilation efficiency in predators

have a lower assimilation efficiency

vascular plants

have high lignin concentrations

phytoplankton

have low lignin concentration so they decompose quickly

nitrogen content

increases as microbial decomposers immobilize nitrogen from outside the litter fungi and bacteria is much higher than that of plant material they are feeding on

rate of decay

is related to 1. the quality of the plant litter as a food source for organisms decomposing it 2. the features of the physical environment that influence decomposer populations

microfauna and microflora

less than 100um includes protists and nematodes living in water in the soil pores

availability of nitrogen

maximum rate of photosynthesis is strongly correlated with nitrogen concentration in leaves availability in the soil or water directly affects rates of ecosystem primary productivity

plant litter

mesh bags make of synthetic material that doesn't readily decompose, with 1-2mm holes holes allow decomposers in an don't let plant material out

Primary production depends on

mineral (inorganic) nutrients taken up by autotrophs

leaching

nitrogen in the litter declines as water soluble compounds are leached out

nitrogen cycling

nitrogen is present but can't be used unless fixed, then it can be brought in usually in the form of ammonia to form proteins. Microorganisms are present in each part of the cycle.

plant tissue senesce

nitrogen is returned to the soil surface as dead organic matter

tea on coastal environments

permanently submerged plant litters decompose more rapidly than those of the surface of the marsh because they are more accessible to detritivores and the stable physical environment is more favorable to microbial decomposers

terrestrial ecosystem

plant bridge is physical separation of zones 1. production in plant canopy 2. decomposition at the soil surface roots access nutrients in soil and vascular stem in the plants transport nutrients to canopy

aquatic ecosystem

plants don't always bridge the separation of zones 1. production in surface waters 2. decomposition in benthic zone

Essential nutrient

plants take up nitrogen from the soil through their roots, it is used to make nitrogen-based compounds.

mineralization

process through which microbial decomposers convert nitrogen and other elements from organic compounds into inorganic forms

net mineralization rate

rate that minerals are supplied to the soil

Carbon to nitrogen ratio

ratio of the weight of organic carbon to the weight of total nitrogen in a soil or organic material decrease ratio doesn't indicate increased nitrogen availability

Retranslocation

recycling of nutrients within a plant

low availability of nitrogen

reduces net primary production and the nitrogen content of plant tissues produced affects input of dead organic matter into the decomposer food chain

dominant plants

rooted in the sediments, linking the zones of production and decomposition

Roots in rhizosphere

roots alter chemistry by secreting carbohydrates into soil, it is a rich source of bacterial growth

salt wedge

salt water moving under(sinking due to density) freshwater into estuary

Particulate Organic Matter (POM)

smaller fragments found within mineral soil horizons

algae

take up nutrients and dissolved organic matter

submerged plants

take up nutrients from both the sediments and the water column

decomposition

the breakdown of the chemical bonds formed when organic molecules and tissues are build

carbon and energy

the carbon compound that is present in plant little is directly related to characteristics of it as an energy source

assimilation efficiency

the percentage of consumed energy that is assimilated

resorption

the process of removing or digesting old bone tissue

rhizosphere

the region of the soil where plant roots function (most of the soil) has intense microbial and fungal activity

immobilization

the uptake and assimilation of mineral nutrients by microbial decomposers

Relationship between microbial decomposers and microbivores

this determines the rate of nutrient cycling in the rhizosphere

F/t decomposition is affected by oxygen concentration of the water

true

T/f bacteria do not decompose ligin

true, only fungi decompose it

Surface Water

winds blowing on the water's surface cause turbulence and mixes the water

T/F heterotrophs are decomposers to some degree

yes! through food digestion organic matter is broken down, altered, and partially released as waste

pycnocline

zone of maximum vertical difference in density