Effects of human disturbances on endemic and threatened plant species in Amani Nature Reserve, Tanga region

Abstract

This study was carried out in Amani Nature Reserve (ANR), Tanga Region, Tanzania to assess the effects of human disturbances on endemic and threatened plant species. Both socio-economic and ecological aspects of human disturbance on endemic and threatened plant species were studied. The socio-economic study involved interviewing 101 households selected at random in five out of 18 villages adjacent to ANR. The ecological survey used a systematic sampling design to acquire these data. A total of 278 (10mx50m) sample plots in five transects were laid out in the reserve. Results showed that, a total of 15 endemic and/or threatened species were used by local communities for making domestic items, 10 for house construction and selling, 7 for medicine, 10 as fuel wood and about 84 tonnes of seed were collected from endemic/threatened tree species. About 93% of respondents had no idea that endemic and threatened plant species occurred in their area. There was evidence of poles and timber cutting of threatened and/or endemic tree species in the reserve. Out of 4001 tree stems evaluated, 3474 (87%) trees were alive, 207 (5%) were recently cut, 90 (2%) were old cut and 230 (6%) had died naturally. The average number of timbersized trees cut per ha in the intact and disturbed forest areas was 18.5 and 24.3 respectively. Out of 3959 evaluated poles, 3515 (88.8%) were alive, 282 (7.1%) were recently cut, 113 (2.9 %) were old cut and 56 (1.4%) were naturally dead. The average cut poles per ha was 23.7 in the intact forest and 29.1 in the disturbed forest area. The Shannon-Wiener index of diversity was 3.778 and 4.190 for intact and disturbed forest strata respectively. The Indices of Dominance (ID) were 0.0445 and 0.0273 for intact ii and disturbed forest strata respectively. Making people more aware of the importance of threatened and endemic plant species, suggesting alternative species and providing off-forest alternative livelihood strategies is recommended for alleviating human disturbances on threatened plant species in ANR.