Non-Timber Forest Products, Forest Structure, and Climate Variability: Implications for Household Livelihood Dependence in the Yangambi Biosphere Reserve, Democratic Republic of Congo

Abstract

Non-timber forest products are central to rural livelihoods in tropical forest regions, yet their availability is increasingly threatened by forest structural degradation and long-term climatic variability. This study investigates the interactions among forest structure, historical climatic trends, and household NTFP dependence in eight villages surrounding the Yangambi Biosphere Reserve. Using a convergent parallel mixed-methods design, the research integrates biophysical forest inventories based on 20 × 20 m quadrats in primary and secondary forests, historical climatic records from 1931 to 2010, stratified household surveys (n = 46), Rapid Rural Appraisal tools, focus group discussions including a women-only group, and key informant interviews. Quantitative data were analyzed using descriptive statistics, Pearson correlations, and chi-square tests in SPSS v26, while qualitative data were subjected to thematic analysis in NVivo 12. Results indicate that primary forests display significantly greater structural complexity than secondary forests, including higher species richness (38 vs. 21), basal area (4.2 vs. 1.8 m²/ha), and canopy cover (70% vs. 40%), which support stronger NTFP diversity and seasonal stability. Climatic analysis shows a 1.2 °C rise in mean annual temperature and a 15% decline in rainfall over the study period, trends that are negatively correlated with perceived NTFP availability (r = -0.62, p < .05) and seasonality (r = -0.58, p < .05). Household dependence on NTFPs is significantly higher among communities located within 5 km of primary forest edges (χ² = 6.47, df = 2, p < .05). Women and female-headed households, representing 30.4% of the sample, demonstrate greater reliance on NTFPs and heightened vulnerability linked to gendered labor roles and structural constraints. Adaptation responses are dominated by agricultural expansion (45.7%) and agroforestry adoption (30.4%), whereas non-farm diversification remains limited (15.2%) due to persistent socio-economic and cultural barriers. These findings demonstrate that interacting ecological degradation and climatic stress are reducing NTFP provisioning, intensifying spatially and gender-differentiated vulnerability, and constraining adaptive capacity. The study highlights the urgency of integrated management strategies that combine forest restoration, climate-resilient agroforestry, spatially targeted livelihood support, and gender-sensitive interventions to sustain ecosystem integrity and rural wellbeing in biosphere reserve transition zones.