The aftermath of environmental disturbance on the critically endangered coffea kihansiensis in the Southern Udzungwa Mountains, Tanzania

Abstract

The endemic Coffea kihansiensis was monitored in the Kihansi gorge over a three year period following diversion of the Kihansi River underground for hydropower production and its associated catastrophic effect on the gorge biota. We assessed the growth status of the coffee population by measuring, along an altitudinal gradient, the height and diameter of 450 randomly selected coffee stems in 18 sampling plots covering ca 1800 m2. We also collected microclimatic data to compare with that collected prior to river diversion. Coffee infestation by parasites was examined by recording the number of stems with signs of infestation. There was no significant change in size of Coffea kihansiensis during the study period. However, the size for immature plants differed between the two sites; LWF and UCF. Parasite infestation differed between reproductive age classes and was greater at lower elevation (800 - 850 m a.s.l) than above, suggesting possible effects of altitude and microclimate on coffee infestation. Increasing habitat degradation, parasite infestations, and loss of the species' ecological envelope seriously undermine the species' growth potential with severe consequences for its long-term population survival. Continued monitoring of the species is recommended, with the emphasis on understanding basic species biology, population trends, and the potential role of assisted migration in saving the population from collapse. © Alfan A. Rija, Kuruthumu A. Mwamende and Shombe N. Hassan.