Expert Consensus on Buffer Zone Governance: Interface Concepts, Ecosystem Service Priorities, and Territorial Strategies Around Cerro Castillo National Park, Chile

Buffer zones around protected areas (PA) face complex governance challenges as territorial transitions accelerate globally, yet limited consensus exists on their definition, ecosystem service (ES) priorities, and management strategies. This study employed a three-round Delphi methodology with 23 transdisciplinary experts to build consensus on buffer zone governance around Cerro Castillo National Park in Chilean Patagonia, using the IPBES ecosystem services framework to structure the analysis. Round 1 employed open-ended questions to explore expert perspectives, Round 2 evaluated 56 statements and 15 strategic components using structured questionnaires, and Round 3 refined non-consensus items. Experts achieved 76.7% overall consensus across three thematic areas: PA interface conceptualization (79.2% consensus on 24 statements), ES assessment (91.2% consensus on 34 statements), and territorial transition strategies (15 components evaluated). Water-related services achieved unanimous agreement across multiple IPBES categories, revealing their potential as boundary objects bridging conservation and development perspectives. Educational approaches and voluntary compliance emerged as high-feasibility strategic components, while regulatory frameworks showed high importance but implementation uncertainty. The study demonstrates that structured expert consultation can identify collaborative pathways for buffer zone governance, with water services providing concrete entry points for multi-stakeholder cooperation and education-based strategies offering promising implementation pathways for sustainable territorial transitions.