Plant Ecology and Evolution 154(3): 391-404, doi: 10.5091/plecevo.2021.1838
Conservation status revision and communities’ perceptions of 22 Aloe species in Tanzania
expand article infoSiri A. Abihudi‡, Hugo J. de Boer§, Anna C. Treydte|
‡ Department of Biodiversity Conservation and Ecosystem Management, Nelson Mandela African Institution for Science and Technology (NM-AIST), Arusha, Tanzania§ Natural History Museum, University of Oslo, Oslo, Norway| Department of Physical Geography, Stockholm University, Stockholm, Sweden

Corresponding author: Siri Abihudi ( abihudis@nm-aist.ac.tz )

© Siri A. Abihudi, Hugo J. de Boer, Anna C. Treydte.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation: Abihudi SA, de Boer HJ, Treydte AC (2021) Conservation status revision and communities’ perceptions of 22 Aloe species in Tanzania. Plant Ecology and Evolution 154(3): 391-404. https://doi.org/10.5091/plecevo.2021.1838
Open Access
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.

Keywords
area of occupancy, community surveys, distribution, Eastern Africa, extent of occurrence, interviews, IUCN category, threatened

References

  • Abeli T., Dalrymple S., Godefroid S., et al. 2020. Ex situ collections and their potential for the restoration of extinct plants. Conservation Biology 34(2): 303–313. https://doi.org/10.1111/cobi.13391
  • Abihudi S.A., de Boer H.J., Rogasian L.A. & Treydte A.C. 2019. Ethnobotanical knowledge and threat factors for Aloe species in Tanzania. Ethnobotany Research & Applications 18(43): 1–28. Available from http://ethnobotanyjournal.org/index.php/era/article/view/1643 [accessed 25 May 2021].
  • Abihudi S.A., Venkataramana P.B., de Boer H.J. & Treydte A.C. 2020. Species-specific responses of “Critically Endangered” and “Least Concern” Aloe seed germination to environmental conditions in Tanzania. Global Ecology and Conservation 24: e01241. https://doi.org/10.1016/j.gecco.2020.e01241
  • Agbani P.O., Kafoutchoni K.M., Salako K.V., et al. 2018. Traditional ecological knowledge-based assessment of threatened woody species and their potential substitutes in the Atakora mountain chain, a threatened hotspot of biodiversity in Northwestern Benin, West Africa. Journal of Ethnobiology and Ethnomedicine 14(1): 1–19. https://doi.org/10.1186/s13002-018-0219-6
  • Alberta Native Plant Council (ANPC) 2012. ANPC guidelines for rare vascular plant surveys in Alberta - 2012 Update, (April), 25. Available from http://anpc.ab.ca/wp-content/uploads/2015/01/Guidelines-For-Rare-Plant-Surveys-in-AB-2012-Update.pdf [accessed 25 May 2021].
  • Arena G., Witkowski E.T.F. & Symes C.T. 2015. Growing on rocky ground: microhabitat predictors for site-occupancy of Aloe peglerae, an Endangered endemic species with a restricted range. South African Journal of Botany 100: 174–182. https://doi.org/10.1016/j.sajb.2015.05.022
  • Awang N.A., Ali A.M. & Mat N. 2018. Alternative medicines from edible bitter plants of Besut, Malaysia. Journal of Agrobiotechnology 9(2): 80–91.
  • Bachman S., Moat J., Hill A.W., de la Torre J. & Scott B. 2011. Supporting Red List threat assessments with GeoCAT: geospatial conservation assessment tool. ZooKeys 150: 117–126. https://doi.org/10.3897/zookeys.150.2109
  • Basmatker G., Jais N. & Daud F. 2011. Aloe vera: a valuable multifunctional cosmetic ingredient. International Journal of Medicinal and Aromatic Plants 1(3): 338–341.
  • Biró É., Babai D., Bódis J. & Molnár Z. 2014. Lack of knowledge or loss of knowledge? Traditional ecological knowledge of population dynamics of threatened plant species in East-Central Europe. Journal for Nature Conservation 22(4): 318–325. https://doi.org/10.1016/j.jnc.2014.02.006
  • Bonar S., Fehmi J. & Mercado-Silva N. 2011. An overview of sampling issues in species diversity and abundance surveys. In: Magurran A.E. & McGill B.J. (eds) Biological diversity: frontiers in measurement and assessment: 11–27. Oxford University Press, Oxford & New York.
  • Burgess N.D. & Kilahama F. 2005. Is enough being invested in Tanzania’s Eastern Arc Mountains? The Arc Journal (17): 2–5.
  • Carter S. 1994. Aloaceae. In: Polhill R.M. (ed.) Flora of Tropical East Africa. A.A. Balkema, Rotterdam.
  • Chen C., Li P., Wang R.H., Schaal B.A. & Fu C.X. 2014. The population genetics of cultivation: domestication of a traditional Chinese medicine, Scrophularia ningpoensis Hemsl. (Scrophulariaceae). PLoS ONE 9(8): e105064. https://doi.org/10.1371/journal.pone.0105064
  • CITES 2016. Consideration of proposals for amendment of Appendices I and II - Proposal 4. Seventeenth Meeting of the Conference of the Parties 21(Prop. 4): 1–23.
  • CITES 2019. Appendices I, II, and III. Convention on International Trade in Endangered Species of Fauna and Flora (CITES) 4(3): 85–87.
  • Cochrane J.A., Crawford A.D. & Monks L.T. 2007. The significance of ex situ seed conservation to reintroduction of threatened plants. Australian Journal of Botany 55(3): 356–361. https://doi.org/10.1071/BT06173
  • Eastern Arc Mountains & Coastal Forests CEPF Plant Assessment Project Participants 2009a. Aloe ballyi. The IUCN Red List of Threatened Species 2009: e.T30901A9584477. gkwz
  • Eastern Arc Mountains & Coastal Forests CEPF Plant Assessment Project Participants 2009b. Aloe boscawenii. The IUCN Red List of Threatened Species 2009: e.T158325A5195623. gkw2
  • Eastern Arc Mountains & Coastal Forests CEPF Plant Assessment Project Participants 2009c. Aloe brachystachys. The IUCN Red List of Threatened Species 2009: e.T158261A5192038. gkw3
  • Eastern Arc Mountains & Coastal Forests CEPF Plant Assessment Project Participants 2009d. Aloe brandhamii. The IUCN Red List of Threatened Species 2009: e.T158082A5182211. gkw4
  • Eastern Arc Mountains & Coastal Forests CEPF Plant Assessment Project Participants 2009e. Aloe bussei. The IUCN Red List of Threatened Species 2009: e.T158040A5184534. gkw5
  • Eastern Arc Mountains & Coastal Forests CEPF Plant Assessment Project Participants 2009f. Aloe congdonii. The IUCN Red List of Threatened Species 2009: e.T157975A5178846. gkw6
  • Eastern Arc Mountains & Coastal Forests CEPF Plant Assessment Project Participants 2009g. Aloe deserti. The IUCN Red List of Threatened Species 2009: e.T158128A5185542. gkw7
  • Eastern Arc Mountains & Coastal Forests CEPF Plant Assessment Project Participants 2009h. Aloe dorotheae. The IUCN Red List of Threatened Species 2009: e.T158335A5195945. gkw8
  • Eastern Arc Mountains & Coastal Forests CEPF Plant Assessment Project Participants 2009i. Aloe flexilifolia. The IUCN Red List of Threatened Species 2009: e.T158247A5191712. gkw9
  • Eastern Arc Mountains & Coastal Forests CEPF Plant Assessment Project Participants 2009j. Aloe kilifiensis. The IUCN Red List of Threatened Species 2009: e.T158221A5190802. gkxb
  • Eastern Arc Mountains & Coastal Forests CEPF Plant Assessment Project Participants 2009k. Aloe leachii. The IUCN Red List of Threatened Species 2009: e.T158318A5195072. gkxc
  • Eastern Arc Mountains & Coastal Forests CEPF Plant Assessment Project Participants 2009l. Aloe leedalii. The IUCN Red List of Threatened Species 2009: e.T158000A5181692. gkxd
  • Eastern Arc Mountains & Coastal Forests CEPF Plant Assessment Project Participants 2009m. Aloe leptosiphon. The IUCN Red List of Threatened Species 2009: e.T158284A5192905. gkxf
  • Eastern Arc Mountains & Coastal Forests CEPF Plant Assessment Project Participants 2009n. Aloe massawana. The IUCN Red List of Threatened Species 2009: e.T157970A5178505. gkxg
  • Eastern Arc Mountains & Coastal Forests CEPF Plant Assessment Project Participants 2009o. Aloe pembana. The IUCN Red List of Threatened Species 2009: e.T158037A5183949. gkxh
  • Eastern Arc Mountains & Coastal Forests CEPF Plant Assessment Project Participants 2009p. Aloe rabaiensis. The IUCN Red List of Threatened Species 2009: e.T158271A5192171. gkxj
  • Eastern Arc Mountains & Coastal Forests CEPF Plant Assessment Project Participants 2009q. Aloe richardsiae. The IUCN Red List of Threatened Species 2009: e.T158176A5187821. gkxk
  • Eastern Arc Mountains & Coastal Forests CEPF Plant Assessment Project Participants 2009r. Aloe volkensii. The IUCN Red List of Threatened Species 2009: e.T158213A5190314. gkxm
  • Eastern Arc Mountains & Coastal Forests CEPF Plant Assessment Project Participants 2009s. Aloe volkensii subsp. volkensii. The IUCN Red List of Threatened Species 2009: e.T158387A5197845. gkxn
  • Godoy F.L., Tabor K., Burgess N.D., Mbilinyi B.P., Kashaigili J.J. & Steininger M.K. 2011. Deforestation and CO2 emissions in coastal Tanzania from 1990 to 2007. Environmental Conservation 39(1): 62–71. ttps://doi.org/fwnxst
  • Grace O.M., Simmonds M.S.J., Smith G.F. & Van Wyk A.E. 2009. Documented utility and biocultural value of Aloe L. (Asphodelaceae): a review. Economic Botany 63(2): 167–178. https://doi.org/10.1007/s12231-009-9082-7
  • Grace O.M., Buerki S., Symonds M.R.E., et al. 2015. Evolutionary history and leaf succulence as explanations for medicinal use in aloes and the global popularity of Aloe vera. BMC Evolutionary Biology 15(1): 1–12. f63mb2
  • Hall J., Burgess N.D., Lovett J., Mbilinyi B. & Gereau R.E. 2009. Conservation implications of deforestation across an elevational gradient in the Eastern Arc Mountains, Tanzania. Biological Conservation 142(11): 2510–2521. https://doi.org/10.1016/j.biocon.2009.05.028
  • Howell K.M., Burgess N.D., Butynski T.M., et al. 2006. The biological importance of the Eastern Arc Mountains of Tanzania and Kenya. Biological Conservation 134(2): 209–231. https://doi.org/10.1016/j.biocon.2006.08.015
  • Huebner C.D. 2007. Detection and monitoring of invasive exotic plants: a comparison of four sampling methods. Northeastern Naturalist 14(2): 183–206. bcwhv9
  • IUCN Standards and Petitions Committee 2019. Guidelines for using the IUCN Red List Categories and Criteria. Version 14. Prepared by the Standards and Petitions Committee. Available from http://www.iucnredlist.org/documents/RedListGuidelines.pdf [accessed 25 May 2021].
  • Kideghesho J.R. & Msuya T.S. 2010. Gender and socio-economic factors influencing domestication of indigenous medicinal plants in the West Usambara Mountains, northern Tanzania. International Journal of Biodiversity Science, Ecosystem Services and Management 6(1–2): 3–12. https://doi.org/10.1080/17451590.2010.480946
  • Larson D.W., Matthes U. & Kelly P.E. 2005. Cliff ecology: pattern and process in cliff ecosystems. Cambridge University Press, New York.
  • Liu H.M., Xu Z.F., Xu Y.K. & Wamg J.H. 2002. Practice of conservation plant diversity through traditional beliefs: a case study in the Xishuangbanna, southeast China. Biodiversity and Conservation 11: 705–713. https://doi.org/10.1023/A:1015532230442
  • Maundu P., Kariuki P. & Eyog-Matig O. 2006. Threats to medicinal plant species – An African perspective. In: Miththapala S. (ed.) Global synthesis workshop “Biodiversity loss and species extinctions: managing risk in a changing world”, IUCN World Conservation Forum, 18–20 November 2004, Bangkok, Thailand: 47–63. Ecosystems and Livelihoods Group, Asia; Asian Regional Office; The World Conservation Union (IUCN).
  • McCaffrey N.B., Blick R.A.J., Glenn V.C., Fletcher A.T., Erskine P.D. & van Osta J. 2014. Novel ‘stratified-meander’ technique improves survey effort of the rare Pagoda Rock Daisy growing remotely on rocky cliff edges. Ecological Management and Restoration 15(1): 94–97. https://doi.org/10.1111/emr.12087
  • Mugambi C.M. 2015. Genetic diversity of Aloe species in Kenya and the efficacy of Aloe secundiflora, Aloe lateritia and Aloe turkanesis on Fusarium oxysporum and Pythium ultimum. Master’s thesis, University of Nairobi, Kenya. Available from http://erepository.uonbi.ac.ke/handle/11295/95984 [accessed 26 May 2021].
  • Murray B.R., Thrall P.H., Gill A.M. & Nicotra A.B. 2002. How plant life-history and ecological traits relate to species rarity and commonness at varying spatial scales. Austral Ecology 27(3): 291–310. https://doi.org/10.1046/j.1442-9993.2002.01181.x
  • Myers N., Mittermeier R.A., Mittermeier C.G., da Fonseca G.A.B. & Kent J. 2000. Biodiversity hotspots for conservation priorities. Nature 403(6772): 853–858. https://doi.org/10.1038/35002501
  • Newton L.E. 2004. Aloes in habitat. In: Reynolds T. (ed.) Aloes: the genus Aloe. CRC Press, Boca Raton.
  • Newton D.J. & Vaughan H. 1996. South Africa’s Aloe ferox plant, parts and derivatives industry. Traffic East/Southern Africa, South African National Office, Johannesburg.
  • Pfab M.F. & Witkowski E.T.F. 1999. Fire survival of the Critically Endangered succulent, Euphorbia clivicola R.A. Dyer - Fire-avoider or fire-tolerant? African Journal of Ecology 37(3): 249–257. https://doi.org/10.1046/j.1365-2028.1999.00176.x
  • Richart M. 2019a. Aloe duckeri. The IUCN Red List of Threatened Species 2019: e.T110717100A110717103. gkxq
  • Richart M. 2019b. Aloe myriacantha. Grass Aloe. The IUCN Red List of Threatened Species 2019: e.T110763474A110763500. gkxr
  • Richart M. 2019c. Aloe nuttii. The IUCN Red List of Threatened Species 2019: e.T110765906A110765909. gkxs
  • Richart M. 2019d. Aloe niensiensis. The IUCN Red List of Threatened Species 2019: e.T110765369A110765372. gkxt
  • Sajem A.L., Rout J. & Nath M. 2008. Traditional tribal knowledge and status of some rare and endemic medicinal plants of North Cachar Hills district of Assam, Northeast India. Ethnobotanical Leaflets 12(24): 261–275. Available from http://opensiuc.lib.siu.edu/cgi/viewcontent.cgi?article=1065&context=ebl [accessed 25 May 2021].
  • Solano E. & Feria T.P. 2007. Ecological niche modeling and geographic distribution of the genus Polianthes L. (Agavaceae) in Mexico: using niche modeling to improve assessments of risk status. Biodiversity and Conservation 16(6): 1885–1900. https://doi.org/10.1007/s10531-006-9091-0
  • Syfert M.M., Joppa L., Smith M.J., Coomes D.A., Bachman S.P. & Brummitt N.A. 2014. Using species distribution models to inform IUCN Red List assessments. Biological Conservation 177: 174–184. https://doi.org/10.1016/j.biocon.2014.06.012
  • Tabor K., Kashaigili J.J., Mbilinyi B. & Wright T.M. 2010. Forest cover and change for the Eastern Arc Mountains and Coastal Forests of Tanzania and Kenya circa 2000 to circa 2010. Final report. Journal of Forest and Livelihood 4(1): 1–10.
  • Veríssimo E.P. 2016. Aloe species in colorectal cancer therapy: friend or foe? Master’s thesis, University of Lisbon, Portugal.
  • Wabuyele E. 2006. Studies on Eastern African aloes: aspects of taxonomy, conservation and ethnobotany. PhD thesis, University of Oslo, Norway.
  • Wabuyele E. & Kyalo S. 2008. WG 3 - Succulents and Cycads. Case Study 1 - Sustainable use of East African Aloes: the case of commercial Aloes in Kenya. In: International Expert Workshop on CITES Non-Detrimental Findings: 1–17. Available from http://www.conabio.gob.mx/institucion/cooperacion_internacional/TallerNDF/Links-Documentos/WG-CS/WG3-SucculentsandCycads/WG3-CS1%20Aloes/WG3-CS1.pdf [accessed 26 May 2021].
  • Wabuyele E., Bjorå C.S., Nordal I. & Newton L.E. 2006. Distribution, diversity and conservation of the genus Aloe in Kenya. Journal of East African Natural History 95(2): 213–225. d6rd99
  • Weber A. 2013. Aloe lateritia. The IUCN Red List of Threatened Species 2013: e.T201337A2700528. gkxv
  • Weber A. & Demissew S. 2013a. Aloe parvidens. The IUCN Red List of Threatened Species 2013: e.T201328A2699860. gkxw
  • Weber A. & Demissew S. 2013b. Aloe secundiflora. The IUCN Red List of Threatened Species 2013: e.T201405A2705516. gkxx
  • Winowiecki L., Vågen T.G., Massawe B., et al. 2016. Landscape-scale variability of soil health indicators: effects of cultivation on soil organic carbon in the Usambara Mountains of Tanzania. Nutrient Cycling in Agroecosystems 105(3): 263–274. https://doi.org/10.1007/s10705-015-9750-1
  • Yan H., Feng L., Zhao Y., Feng L., Wu D. & Zhu C. 2020. Prediction of the spatial distribution of Alternanthera philoxeroides in China based on ArcGIS and MaxEnt. Global Ecology and Conservation 21: 1–15. https://doi.org/10.1016/j.gecco.2019.e00856