detritus ecosystem

Detrius ecosystems are ecosystems which partially or fully depend o the dead organic matter produced in another ecosystem.Example:-Cave ecosystem.In certai subcomponents of the ecosystem,energy is derived from the detrius in the system obtained through decomposition as is the case with some autotroph based ecosystems.

Decomposition is important for obtaining detrius through fragmentation,leaching but primarily by tyhe activity of organisms that may facilitate both leaching & fragmentation.However,it must be pointed that not all parts get decomposed at the same time or at the same rate,lignin decays more slowly than cellulose as an example.on the basis of the environment in which the detrius is decomposed it is subcategorized into the followinfg divisions:-

1)detrius decomposition in forest ecosystem;

2)detrius decomposition in grasslands;

3)detrius decomposition in chapparral;

4)detrius decomposition in deserts;

5) detrius decomposition in aquatic ecosystems.

The action of microbes result in mineralization & soil humification which provides the essential nutrients taken up by the plants by the osmotic pressure through it's roots.Then it is made available to other organisms.

Ovington in a generalised attempt proposed that:-

1)greater litter fall occurs with increasing distance from the equator;

2)temperate soft wood forests contain about 4 ties the amount of litter fall present in temperate hard wood forests.

 

Vogt et al.,have demonstrated patterns of forest floor accumulation are separated by evergreenness or decidiousness of foliage.Tropical,subtropical & warm temperate forests located at latitudes less than 40( degrees) have similar mean accumulation of forest floor mass under the deciduous or evergreen foliage.

In temperate evergreen forest 38% of net production in this ecosystem passes through detrius food chain.Decomposition in sub-arctic woodland soils is slow due to low soil temperature,low soil ph & paucity of a source of energy for running the ecosystem & hence,less dependence on detrius as a source of energy for running the ecosystem.A reservoir of nutrients remain unavailable in subarctic woodland soils.

 

In prairie ecosystem, 60% - 90% of net primary productivity & 90% of secondary prouctivity occurs in soil since,harbivory & decomposition are 2 important trophic pathways.Microbial community is termed as "invisible prairie",here the standing microbial biomass is estimated second only to primary producers.thus,we find predominance of detrius based energy from prairie ecosystem.

In temperate deciduous forest ecosystem,detrius supply & the subsequent energy associated with it comes from:

1)leaves=83%

2)Root deaths=12%

3)Non-leaf literfall=2%

4)Organic matter via precipitation=2%

5)Fecal material=0.9%

6)Euded by roots=0.1%

7)Animal deaths=Traces

Decompositon of lea litter in coastal mountains chapparrel in south california during intervals between natural fies may be substantial source of plant nutrients for chaparral growth.It has been observed by Schlisinger & Hasey,over a period of time chlorophyll shrub ost 15% - 19% & deciduous shrub lost 20% - 24% of it's ash free dry mass with mean residence time for organic matter in litter of 5.3yr to 7.7yr.This supports the contention that decomposition of litter layer is important to the supply of available nutrients in mature chaparral.

 

In desert ecosystem,The amount of energy entering the desert ecosystem is determined by the micro arthopods population(i.e.,mice-collembola, Psocoptera etc.) which regulates decomposition of buried litter by regulating population size of bacterial grazers, caphalobidae nematodes.An experiment by exclusion of micro arthropods resulted in 53% reduction in decomposition.

In aquatic ecosystem,it is unknown about which microorganisms carry this activity.Decomposition is influenced by environmental factors such as temperature,oxygen,quality of decomposable material etc.Example:-in root spring,at concord,in Massachusetts(USA),more than 3 times as much energy enters the system in the form of dead organic material or detritus than was fixed by photosynthesis & the enrgy is largely external in origin.

In a woodland ecosystem,Petersen et al.,found that standing crop detritus ranged from 87.8g/metre sq. - 970.9g/metre sq.Chespake bay estuarine ecosystem is found to be producing 70% of detritus by itself and the rest being imported from lotic systems feeding the bay.

In ocean ecosystem,photosynthetic planktons are autotrophic producers and are at the base of grazing & detritus food pathways,large reaction of primary production is not consumed directly by herbivores but is subject to to detrial decomposition by bacteria.

In conclusion,it can be said the contribution of detrius chain in energy flow in running any ecosystem is indispensable & is important for energy flow studies of detritus based ecosystem.As we have seen in the aforesaid discussion that 90% of energy flow in many communities may be through detrius feeders & have proved that detritus is of greater importance in the ecosystem than that of the herbivorous/carnivorous/omnivorous grazing chains.

The decomposition of detritus liberates stored nutrients making them available for feeding of autotrophic productivity.Thus,initiating cyclic turnover of these nutrients.Example:-Waring & Schlesinger showed that decomposed detrius provides 69% - 87% of the nutrients needed annually for forest growth.