A new analysis approach for long-term variations of forest loss, fragmentation, and degradation resulting from road-network expansion using Landsat time-series and object-based image analysis

摘要

Despite facilitating transport by low-volume roads for multiple purposes, these roads also open corridors to the remote pristine forests and accelerate forest dynamics with deleterious consequences to the forest functionalities and indigenous inhabitants. We assessed the spatial variations of Hyrcanian forest loss, fragmentation, and degradation resulting from the expansion of rural, logging, and mine roads between 1966 and 2016 in northeast Iran. Various data were employed to generate a precise road network; the density of road segments was weighted on the basis of their carrying capacity during 1966-1986, 1986-2000, and 2000-2016. Three dimensions of forest changes were retrieved using the Landsat time-series and object-based image analysis. The spatial patterns of high rates of forest changes were clustered using spatial autocorrelation indicators. The spatial regression models were carried out to explore relationships between forest change and road expansion. The results showed that rural roads were upgraded but forest and mine roads remarkably expanded in recent decades. The spatial variations of forest-dynamic patterns have been changing from forest loss (1966-2000) to forest fragmentation and degradation (1986-2016). The high density of rural roads was significant on the high rates of forest loss and fragmentation during 1966-2000, and the expansion of forest and mine roads significantly intensified the rates of fragmentation and degradation during 1986-2016. Our findings suggest for mitigating destructive schemes over Hyrcanian forests, developing either protected areas or joining unprotected forests to the reserved areas should be prioritized.