Title or substance? A policy impact evaluation of nature reserves upgrade in China's borderlands

Nature reserves (NRs) serve as a critical instrument for curbing biodiversity loss, facilitating ecosystem restoration, and safeguarding ecological security in border regions. However, does the “upgrading” of reserve status lead to “substantive” ecological improvements, or is it merely a nominal designation? To address this question, this study treats China's phased reserve upgrades since 2007 as a quasi-natural experiment. Drawing on balanced panel data from 89 NRs across nine border provinces over the period 2000–2022, we employ a Propensity Score Matching combined with Difference-in-Differences (PSM-DID) approach to provide the first empirical evaluation of the policy effects of NR upgrading in China's border regions. Our findings reveal that: (1) The upgrading policy significantly enhances habitat quality in China's border regions, confirming its de facto ecological benefits. (2) However, the policy effects are not homogeneous but exhibit substantial structural heterogeneity—the effects are more pronounced in southern regions than in northern ones, in biodiversity conservation priority areas than in non-priority areas, in ecosystem-type NRs than in species/heritage-type NRs, and in NRs administered by the forestry and grassland authorities, reflecting a path-dependent pattern of “focused reinforcement” under sectoral dominance. (3) These findings call for future policies to move beyond the nominal goal of “upgrading for upgrading's sake” and instead optimize the strategic layout of upgrading, incorporate protection-object and administrative-competence criteria into the approval process, and translate upgrading into tangible effectiveness through differentiated management and institutional refinement. By constructing a quasi-experimental evaluation framework with panel data, this study provides rigorous empirical evidence for disentangling the de jure versus de facto effects of NR policies, and offers China-based evidence for the global conservation debate between “expansion” and “upgrading.”