Protected areas play a critical role in conserving biodiversity and ecosystem services, yet their effectiveness in mitigating anthropogenic pressures, particularly in fragile alpine ecosystems like the Three-River-Source region of the Qinghai Plateau—a vital water tower for Asia—requires long-term and rigorous assessment. This study evaluates the effectiveness of the Three-River-Source Nature Reserve by analyzing spatiotemporal changes in the human footprint from 2000 to 2024. Utilizing a globally consistent human footprint dataset refined with high-resolution grazing intensity data for the Qinghai Plateau, we compared human footprint dynamics inside and outside the reserve and across its three functional zones (core, buffer, experimental). To isolate the policy effect, we employed a propensity score matching (PSM) approach to control for confounding geographical and socio-economic factors. Results indicate that while human pressure increased overall, the nature reserve was partially effective. The PSM-based comparison revealed that the increase in human footprint inside the nature reserve was lower than in matched external control areas. This effect was spatially heterogeneous and positively correlated with management intensity: it was most pronounced in the core zone, moderate in the buffer zone, and negligible in the experimental zone. The conservation outcomes showed notable improvement following policy enhancements, particularly after the national park’s formal establishment. The findings confirm the value of strict internal protection and functional zoning but highlight the challenge of intensifying peripheral pressures, underscoring the need for integrated landscape-level management strategies beyond the reserve’s boundaries to ensure long-term ecological integrity.

Assessing the effectiveness of protected areas is crucial for refining conservation policies, yet it remains challenging in remote, biodiversity-rich tropics due to logistical constraints. To address this challenge, we developed a remote sensing-based Pressure–State–Benefit (PSB) framework comprising four dimensions: human activity, ecosystem pattern, ecosystem quality, and ecosystem services. Using the Hainan Tropical Rainforest National Park (HTRNP) as a case study, we evaluated conservation effectiveness at the park scale by comparing ecological changes before (2015–2020) and after (2020–2025) its establishment. We further compared the Core Protection Zone (CPZ) and the General Control Zone (GCZ) to reveal differences in conservation outcomes under distinct management regimes. The establishment of HTRNP effectively curbed cropland and built-up land expansion. During 2020–2025, landscape patterns improved, characterized by enhanced connectivity and reduced fragmentation. Concurrently, fractional vegetation cover increased at an accelerated rate, indicating improved ecosystem quality, while key ecosystem services showed upward trends. Notably, the CPZ maintained superior ecological conditions with steady improvements under strict protection, whereas the GCZ, being more sensitive to human disturbances, exhibited fluctuating outcomes. This study demonstrates the effectiveness of HTRNP in enhancing regional ecosystem conditions and highlights the importance of zoned management. Furthermore, the proposed PSB framework offers a transferable approach for comprehensively assessing conservation effectiveness in other protected areas.