**3. Theoretical Biomass Potential**

Thirty-one research studies include an assessment of the theoretical biomass potential (Table 1). In eighteen of these studies, the theoretical biomass potential is combined with the assessment of either available, technological, economical or environmental biomass potentials. Various studies have used allometric equations to predict the theoretical biomass potential based on in-field measures of height and diameter allowing them to estimate the overall above-ground biomass ratios [54–60]. For the purpose of bioenergy, these studies are rather informative literature on the ratio of above-ground biomass in order to assess the theoretical biomass potential without including any losses or alternative uses of the biomass. One can consider them indications of the upper-bound of biomass in the respective location and forest type. Similarly, an allometric equation is used to determine CWD removal benchmarks in the native forest of eastern Australia with the results being very specific for dead material only [49]. The study delivers good insight into the methods used to estimate the upper-bound of CWD but has no indication of further losses or potential of this biomass when extracted. Ximenes et al. (2006 and 2008) assessed the green weight of biomass using purpose-built trailers with built-in measuring devices [61,62]. The method provides an indication of the ratio of biomass in different forest types including some of the key tree species. The assessment of the theoretical biomass potential is once again restricted to a maximum allocation of the biomass without any indication of losses or harvestable volumes. Several papers calculated biomass quantity using the Cooperative Research Centre (CRC) for Forestry standard methodology [63] for sampling remaining slash [23,64–70]. In each of the papers, the CRC methods give a good indication of the number of residues that are left on-site before and after the removal of forest biomass. The methods have been tested in several case studies across Australia and have been applied in different harvesting systems like whole-tree, cut-to-length and integrated harvesting.


*Energies* **2020**, *13*,

 1147


**Table 1.** *Cont.*
