Prescribed Burning in Post-Logging Dry Dipterocarp Buffer Zones: When Fire Is Necessary But Not Sufficient — Evidence from HKK Wildlife Sanctuary and the Pioneer Species Complication

Abstract Buffer zones of protected areas in post-logging dry dipterocarp forest (DDF) present a specific and underexplored management challenge: annual prescribed burning is ecologically justified and practiced, yet field evidence indicates it is not producing adequate forage for large herbivore populations. This paper uses the Biodiversity Entropy Index (BEI) and field data from the HKK Wildlife Sanctuary buffer zone (17,000 ha, Uthai Thani Province) to examine why prescribed burning alone is insufficient in post-logging DDF, and proposes a combined management framework that integrates BEI monitoring with pioneer species control. BEI analysis shows the HKK Buffer Zone at 595 (MANAGED_USE, borderline RESTORATION), with a predicted +18.7% increase under targeted micro-burning (ventilation index 3,859 m²/s, November–December). However, field data from Kuaraksa et al. (2022) and a forage dynamics study (2022) reveal a critical complication: following cessation of logging in 1989 and subsequent fire suppression programs (2002), pioneer species — primarily Cratoxylum spp. and Croton spp. — have colonized at densities over 1,000 stems/ha, suppressing palatable grasses and preventing recovery of the forage structure that DDF prescribed burning is intended to maintain. Annual prescribed burning continues but produces inadequate forage because pioneer shrubs survive low-intensity surface fires and re-establish dominance rapidly. We propose that BEI provides the measurement framework for tracking recovery, but that effective restoration of this edge case requires a two-component intervention: targeted micro-burning combined with active pioneer species control (mechanical or biological). Field validation of this combined approach requires collaboration with Thailand's DNP, but the predictive framework and site-specific BEI monitoring protocol are presented here. Keywords: dry dipterocarp forest, prescribed burning, pioneer species, post-logging recovery, BEI, buffer zone, forage dynamics, Huai Kha Khaeng, Cratoxylum, management framework