Quantifying the Effect of Riparian Deforestation on Stream Thermal Regime and Macroinvertebrate Community Structure in Plateau State

Riparian forest removal eliminates shading from stream channels, causing thermal regime shifts that can fundamentally alter aquatic macroinvertebrate communities sensitive to temperature changes. This study quantified the effect of riparian deforestation on stream water temperature and macroinvertebrate community structure in highland streams of Plateau State using a comparative paired-stream approach. Twelve streams were categorised by riparian condition: forested, partially cleared, and fully deforested. Continuous water temperature loggers recorded hourly thermal data over twelve months. Macroinvertebrate communities were sampled seasonally using standardised kick-net methods, and assemblages were analysed using multivariate ordination and thermal preference trait analysis. Results showed significantly higher daily maximum temperatures and greater thermal variability in deforested streams, with maximum temperatures exceeding 28 degrees Celsius in fully deforested reaches during dry season months. Macroinvertebrate community composition shifted significantly with riparian condition, with cold-sensitive Ephemeroptera, Plecoptera, and Trichoptera taxa absent from deforested reaches. Trait-based analysis showed clear community-level shifts toward warm-tolerant and pollution-tolerant taxa with increasing riparian deforestation. Water temperature emerged as a stronger predictor of community composition than chemical parameters, underscoring the primacy of thermal habitat in highland stream ecology. The study provides the first quantitative evidence of riparian deforestation thermal effects on Nigerian highland stream invertebrates and recommends mandatory riparian reserve policies in Plateau State watershed management regulations. Keywords: riparian deforestation, stream temperature, macroinvertebrates, Plateau State, thermal regime.