2.3.5. Balance of soil nutrient reserves and aboveground
nutrient export
Total export quantities of nutrient from stem and bark
biomass were estimated by obtaining the product of total
biomass (Mg ha1) from each compartment by the average of
estimated nutrient concentrations (mg kg1) of that compartment.
In order to conduct a comparable evaluation of the
potential effect of each species on soil nutrient reserves, it was
decided to fix a standard harvestable volume (bark þ stems) of
100 Mg ha1 for all the selected species. The relationship
between estimated exported nutrients (bark þ stem) and the
nutrient reserves in the soil up to 45 cm depth, known as the
Stability Index was estimated [20]. This relationship can be
used as an indicator for ecological stability for the management
of production systems, hence, values of Stability Index <
0.6% will be considered as very stable and values >100% as
extremely unstable [20].