WATER S.O.S TASMANIA - The Bio-mass of Trees
The tree is broadly speaking bio-mass zones. These are the stem, the crown, the detritus, humus and the root associates.

Forests are dependent on a constant input and output of nutrients, the tree has shed it’s weight many times over to earth and air and has built much of the soil it stands in where micro-organisms fix the nutrients by interacting with the mosses, lichens, fungi, ferns, the litter on the forest floor, the soil and the breakdown of bed rock.
Fungi play multiple roles in ecosystems everywhere. They are parasites, mutualists and decomposers. Without them, terrestrial life would have a completely different evolutionary trajectory.
The living tree stands in a zone of decomposition much of it transferred, reborn, transported, acts as a filter system, water production or is re-incarnated into mosses, fungi, bacteria, insect life, birds and mammals etc.
The zone of decomposition and nutrient replacement is lost forever and the soil progressively exhausted wherever plantations and mono-culture regrowth replace complex native forests.
These processes essential for maintaining high quality water productivity, are lost forever where ever present forest management practices or land clearing takes place.
Research has shown there can be as much as 550 tonnes per hectare of logs on the forest floor of old Ash or Wet Sclerophyll forests.
SEE : How a Tree Interacts with Rain in an Undisturbed Forest
The total average bio-mass of old Ash or Wet Sclerophyll forests is around 1500-2000 tonnes per hectare, this includes the underground root mass.

SEE : Carbon Sequestration
SEE: Secrets Of Cooperation Between Trees And Fungi Revealed
Ref : Timber Workers for Forests