Forest roads regulate native and exotic species diversity and adjacent soil properties in Lawachara National Park, Bangladesh

The biotic and abiotic components of ecosystems are altered by forest roads, which influence the temperature, humidity, wind speed, and light availability and alter the composition and diversity of plant communities. In this study, we aimed to examine and compare the diversity index of native and exotic species and soil chemical properties along the park's main forest routes in Lawachara National Park (LNP), the northeastern hill forest of Bangladesh. Ten transects were built along the main forest routes into the forest interior. Soil and vegetation data were collected along the transects with three sample plots each measuring 20 m × 20 m and placed at three different distances from the road's side (10 m, 50 m, and 90 m). The Shannon–Wiener index, species richness, Pielou's index, and density of all stems (DAS) were used as variables to determine the diversity of exotic and native plant species in each plot. The results revealed that the diversity indices and DAS for exotic species varied showing a negative correlation and declined their values as the distance from the roadside increased. However, the diversity indices and DAS for native species increased and showed a positive correlation with increasing distance from the road edge. Soil pH, organic matter, and index of disturbance severity (IDS) were also shown to be affected by the proximity of forest roads where the pH and IDS values decreased with increasing distance from the road to the interior forest indicating a negative relationship between distance and these variables. But there was a positive correlation between organic matter and distance from the road edge to the interior forest. Forest managers need to be aware of the potential effect of forest roads. Evaluation of the road-affected zone should be taken into account long term in the monitoring of forest ecosystem biodiversity by the forest authorities.