The impact on orchid species abundance of gathering their edible tubers by HIV/AIDS orphans : a case of three villages in the Southern Highlands of Tanzania

This paper examines the gathering of wild orchids and its effect on orchid species diversity and abundance in rural communities with high prevalence of HIV/AIDS and high numbers of orphans. The study was conducted in three villages in the Makete District of Tanzania. The study used a triangulation of ethnobotanical, anthropological and sociological methodologies. on the three gathering sites, we found a total of 12 different orchid species (7 edible and 5 non-edible ones) confirmed by an expert botanist, although local gatherers identified many more species. The Shannon-Wiener diversity index significantly differed among the three gathering sites. Analyses of focus group discussions and household surveys revealed that HIV/AIDS orphans and non-orphan children were the main gatherers of wild orchids. HIV/AIDS orphans (n = 55) gathered significantly more frequently (4.1 +/- 1.8 times per week) than non-orphan children (n = 49; 1.9 +/- 1.3 times per week) (P <0.01). There was a statistically significant interaction between village and type of gatherer (P <0.05). Scattered observations of changes in orchid species abundance over time were (lone using gatherers' indigenous knowledge and opinions. Orchid abundance peaked during May 2006. The study showed increasing abundance of non-edible orchid species and decreasing abundance of edible ones. There were highly significant, linear negative relationships between gathering pressure on the one hand and total number of orchid plants, total number of orchid species, number of edible orchid plants and number of edible orchid species on the other. These relationships were not statistically significant for non-edible orchids. We surmise that gathering edible orchid tubers is likely to become unsustainable, because once its tuber is harvested the plant does not recover or survive