Question

What physical and biological processes breakdown leaf litter in streams ( steps) whay the characteristics found in this type of stream and the macro-invertebrates that break down the leaf litter?

Answer 1

For streams with a stable and moderately high water temperature, ranging between 18 to 20 degree celcius, the breakdown of leaf litter is quite high. Another factor determining the rate of leaf litter breakdown will be the type of leaf. Leaves with a softer texture, lower tannin content and higher nitrogen content, will be decomposed faster than those leaves which are tough .

* The leaves that fall down into the stream are exposed to the fast water current and carried away.

* There will be physical shredding of the leaves as they will be dashed against rocks , the bed of the stream or any other physical structure that might come on their way.

* The sporulation activity of aquatic hyphomycetes and other aquatic microinvertebrates will change the original leaf chemical composition.

* The action of the microinvertebrates will change the organic content matter , carbon, nitrogen and ergosterol.

* Fungal biomass will increase and the leaf biomass will decrease as its contents are converted by coloniasation of the leaves by the microinvertebrates.

* The high fungal activity associated with rapid leaf breakdown appears to be characteristic of leaf processing in tropical streams.

So, it can be assumed that breakdown of leaf litter will be affected by the temperature of the stream , the type of leaf, the processes of physical shredding of the leaf and the abundance of fungal and other microinvertebrates in the stream water.