Tier 2 REDD assessment of carbon stocks in a biodiversity hotspot and UNESCO World Heritage Site candidate: Mt. Apo Natural Park, Philippines

Background/Question/Methods

Less than 7 % of tropical forest remains in the Philippines due to deforestation. The United Nation’s Reduction of Emissions from Deforestation and Degradation Program (REDD) estimates that this forest loss emits between 0.8 to 2.5 Pg C per year. This forest loss leads to a reduction in endemic species that has led to the Philippines being ranked the 4^thBiodiversity Hotspot in the world. Establishment of conservation areas is a possible mechanism to reduce deforestation.  In 2009, the 54,975 ha Mt. Apo Natural Park (MANP) in Mindanao Island, Philippines was recognized as a candidate UNESCO World Heritage site. However, MANP has a resident population, is a haven for communist insurgents, and is divided into 3 land use areas, including a multiple use zone (MUZ) that may still produce emissions, a restoration zone (RZ), and a strict protection zone (SPZ). Consequently, we conducted a REDD Tier 2 study to estimate baseline above-ground carbon stocks and compare the carbon stocks between land uses. We assumed that: SPZ > RZ > MZ’s carbon stocks. We simultaneously collected field and 5-m airborne interferometric radar (IFSAR) data. We measured species importance, height, crown area, and diameter-at-breast height (dbh) with field methods including a terrestrial laser scanner. We compared three different allometric equations for prediction of biomass. The best-fit biomass model was used to calibrate IFSAR slope and texture characteristics to produce a 2013 biomass and carbon map of MANP.

Results/Conclusions

We found that carbon ranged from 2.5 to 1,509 Mg C ha^-1 and that the restoration zone (RZ) with a mean of 1,617 Mg ha^-1 was the most productive site and the multiple-use zone (MUZ) at 94.8 Mg ha^-1 was the least productive.