## 3 Classification of Global Land Development Phases  
### LDPs Based on Forest Stock Changes  
Based on forest stock changes and adopting FT theory, land sustainability status can be classified into three phases: early transition as a degradation phase, late transition as a restoration phase and post-restoration as a sustainability phase. In FT theory, forest variables and attributes, such as forest area, forest stock, forest biomass and forest carbon, are suggested variables. However, quality also needs to be accounted for; for example, forest area represents the quantitative amount of forest, but not the quality of the forest in such an area [47]. Therefore, we adopted forest stock as the classification variable, as it incorporates both quality and quantity. The average of five-year forest stock changes was calculated and aggregated into 20-year intervals, 1950-1970, 1970-1990 and 1990-2010. Forest degradation was defined as an aggregated average value in the time series of below zero (negative), decreasing forest stock. Forest restoration and sustainable management were defined by stock values above zero (positive). The analysis also considered changes through time: trends from negative to positive were regarded as restoration or reaching a sustainability phase and good management, while declining trends were regarded as approaching a degradation phase. This approach is also an attempt to reflect current forest management activities to mitigate climate change through increasing forest stock for carbon sequestration and adaptation based on Reducing Emission from Deforestation and forest Degradation (REDD+) activities in developing countries [48]. In addition, it could represent sustainable forest management schemes in certified forests [49]. After synthesizing the data and evaluating the trends over the three 20-year periods, we divided the countries into eight zones (Figure 4). Figure 3: Conceptual flows for classifying and implementing land development phases (LDPs). Figure 4: Classification of the eight zone for LDPs classification (degradation, restoration and sustainability). FSC, forest stock change. Figure 4 indicates the patterns of each zone and LDPs. The eight zones were calculated using trends in restoration and degradation over the three time periods, i.e., increasing or decreasing forest stock in a given time period. Therefore, there were eight combinations as follows: Zone 1 (decreasing-decreasing-decreasing), Zone 2 (decreasing-increasing-decreasing), Zone 3 (increasing-decreasing-decreasing), Zone 4 (increasing-increasing-decreasing), Zone 5 (decreasing-decreasing-increasing), Zone 6 (increasing-decreasing-increasing), Zone 7 (decreasing-increasing-increasing) and Zone 8 (increasing-increasing-increasing). The classification used the 2010 status as the end point; therefore, decreasing forest stock from 1990-2010 was degradation, and increasing forest stock from 1990-2010 was restoration. In the degradation phase, overall forest stock change (FSC) was below zero, and it implied that countries lost their forest stock due to negative environmental conditions in the forest or management failure. In the restoration phase, some absolute values of the FSCs were below zero, but most were above zero between 1990 and 2010. In addition to classification by the zones, countries were also assigned an overall LDPs status. Countries with FSCs remaining in degradation from 1950-2010 were classified as in a degradation phase. Countries with FSCs indicating restoration from 1990-2010, but having experienced degradation from 1950-1990 or degradation from 1970-1990 were classified as the restoration phase. Countries with forest stock growth from 1970-2010 were classified as the sustainability phase. Therefore, Zones 1 to 3 were regarded as the degradation phase because of the timing of the decreasing forest stock. Zone 5 was regarded as the restoration phase, and Zone 8 was regarded as the sustainability phase.