Evaluating the status of forest understory plants on high demand in an “open access” setting for restoration and community engagement

Abstract

Knowledge of how human harvest impacts plants on high demand for non-timber forest products is essential for targeted conservation. Herbs and shrubs are some of the main sources of such products. However, documentation of human impact on forest flora usually focuses trees. We assessed the status of three forest understory shrubs on high demand for various non-timber forest product uses around Mabira Central Forest Reserve, Uganda. Acalypha neptunica is popular for commercial meat roasting and vending. Citropsis articulata and Calamus deerratus are collected for medicine and furniture making respectively. Harvest impact on A. neptunica and C. articulata was assessed using transects with human trails as a reference in 12 of the 66 management compartments of the reserve. C. deerratus, was assessed through a reserve-wide search. A. neptunica and C. articulata increased significantly with distance from human trails (Jonckheere-Terpstra Tests: A. neptunica, p = 0.022; C. articulata, p < 0.0001) suggesting occurence of human harvest impact on density. All species showed significant decrease uphill from the valley bottoms (Jonckheere-Terpstra Tests: C. articulata, p < 0.0001; C. deerratus, p < 0.0001; and A. neptunica, p = 0.004) indicating intrinsic vulnerability due to habitat specificity. Interspecies comparisons of density showed A. neptunica to be much more abundant than C. articulata. C. deerratus was localized to patches along some, but not all valley bottoms. A. neptunica exhibited a high level of post-harvest re-sprouting and appeared favored by moderate forest disturbance. C. articulata also showed frequent re-sprouting. These results complement prevailing understanding that conservation actions are urgently needed for C. articulata and C. deerratus. The results also show that further long-term investigation is required to fully understand the plants’ response to harvesting and this needs to be facilitated by enforcing the existing strict nature reserve status of the core of the forest.