Intra-Annual Identification of Local Deforestation Hotspots in the Philippines Using Earth Observation Products

Arnan B Araza,Martin Herold,Ramon A Razal,Maya Gabriela Q Villaluz,Johannes Reiche,Eric D Buduan,Lars Hein,Gem B Castillo,Yaqing Gou

doi:10.3390/f12081008

Abstract

Like many other tropical countries, the Philippines has suffered from decades of deforestation and forest degradation during and even after the logging era. Several open access Earth Observation (EO) products are increasingly being used for deforestation analysis in support of national and international initiatives and policymaking on forest conservation and management. Using a combination of annual forest loss and near-real time forest disturbance products, we provide a comprehensive analysis of the deforestation events in three forest frontiers of the Philippines. A space-time pattern mining approach was used to map quarterly deforestation hotspots at 1 km pixel size (100 hectares), where hotspots are classified according to the spatial and temporal variability of the 2000–2020 deforestation in the study area. Our results revealed that 79–81% of the hotspots overlap with primary forests and 27–29% are inside the state-declared protected areas. The intra-annual analysis of deforestation in 2020 revealed an alarming trend, where most deforestation occurred between the 1st and 2nd quarter (92–94% in hotspot forests; 87–89% in non-hotspot forests), highly overlapping within the slash-and-burn farming season. We also found “new” hotspots (2020) formed mostly from landslide scars and partly from selective logging, the latter is believed to be underestimated. Our study paves the way for rapid and regular assessment of the country’s deforestation, useful for the respective environmental institutions who convene several times a year. Moreover, our findings assert the imperative of alternative livelihoods to upland farmers, efficient forest protection activities, and even the mitigation of landslide risks.

Highlights

Forests provide a broad range of ecosystem services including the mitigation of climate warming and its adverse consequences [1] and the regulation of water to sustain croplands and even mitigate potential floods [2]
Hotspots that account for the deforestation from 2000 to 2020 were found to exist in the whole study area for both maps that use the Radar for Detecting Deforestation (RADD) and GLAD alerts
Results from the two hotspot versions were close for hotspot classes with on-and-off deforestation and those hotspots formed in recent years

Summary

Introduction

Forests provide a broad range of ecosystem services including the mitigation of climate warming and its adverse consequences [1] and the regulation of water to sustain croplands and even mitigate potential floods [2]. The tangible benefits from forests are obviously timber and non-timber forest products; unabated timber harvesting has led to forest loss in most tropical regions [3,4]. Deforestation is blamed for directly causing forest fragmentation and abandoned landscapes, indirectly leading to the decline of forests’ ecosystem services including biodiversity [7,8]. Like many other tropical countries, the Philippines has experienced historical and persistent forest loss, where the peak of deforestation happened from 1977 to 1988, driven by

Methods

Results

Discussion

Conclusion