Conservation status revision and communities’ perceptions of 22 Aloe species in Tanzania

Siri A Abihudi,Hugo J De Boer,Anna C Treydte

doi:10.5091/plecevo.2021.1838

Abstract

Background and aims – Many Aloe species are globally threatened due to overharvesting for trade and habitat destruction. CITES regulates their international trade. In Tanzania, 50% of all existing Aloe species had previously been assessed, though some of these assessments were Data Deficient. For those with sufficient data, an update is required as the rate of decline has rapidly increased over the last years. Material and methods – We estimated Area of Occupancy (AOO), Extent of Occurrence (EOO), and number of locations for 22 Tanzanian Aloe species using the Geospatial Conservation Assessment software (GeoCAT). We assessed the reasons leading to their decline based on direct field observations and community perceptions. Key results – We revised the conservation status of 22 Aloe species; two were assessed as Critically Endangered, ten as Endangered, five as Vulnerable, and five as Least Concern. We re-discovered the Critically Endangered Aloe boscawenii, which had not been seen in Tanzania for more than six decades. We propose to downgrade the endemic Aloe dorotheae, Aloe leptosiphon, and Aloe flexilifolia from Critically Endangered to a lower threat level. The community perception on Aloe species availability did not accurately reflect their categorisation based on the IUCN criteria B. We identified agricultural activities and climate change effects as the two main threats to Tanzanian Aloe species.Conclusion – We conclude that overall numbers are declining for 22 Aloe species in Tanzania, mainly due to human activities. We recommend the implementation of laws and policies to protect their natural habitats.

Highlights

The genus Aloe L. contains over 500 species of succulent flowering plants (Veríssimo 2016)
Some Tanzanian Aloe species have never been assessed for the IUCN Red List (Not Evaluated), and some species listed as assessed do not have enough available data to be certain about their status such as A. niensiensis L.E.Newton (Richart 2019d)
We evaluated the conservation status of 22 Aloe species in Tanzania and found that 77% of these species are threatened

Summary

Introduction

The genus Aloe L. contains over 500 species of succulent flowering plants (Veríssimo 2016). Aloe species are known for their medicinal, cosmetic, and ornamental uses (Newton & Vaughan 1996; Grace et al 2009), where Aloe vera (L.) Burm.f. is the most widely known species (Basmatker et al 2011; Mugambi 2015). Aloe species occupy a wide range of habitats, from forests to exposed rock surfaces and cliff faces, across a considerable altitudinal range, from sea level (e.g. A_boscawenii Christian, A. kilifiensis Christian). The Eastern Arc Mountains and Coastal Forests CEPF Plant Assessment Project assessed the threat level for 19 Aloe species in the Eastern Arc Mountains and Coastal Forests, two of Tanzania’s biodiversity hotspots (Eastern Arc Mountains & Coastal Forests CEPF Plant Assessment Project Participants 2009a, 2009b, 2009c, 2009d, 2009e, 2009f, 2009g, 2009h, 2009i, 2009j, 2009k, 2009l, 2009m, 2009n, 2009o, 2009p, 2009q, 2009r, 2009s). Some Tanzanian Aloe species have never been assessed for the IUCN Red List (Not Evaluated), and some species listed as assessed do not have enough available data to be certain about their status such as A. niensiensis L.E.Newton (Richart 2019d)

Methods

Results

Discussion

Conclusion