Bioquality, Stars and
Botanical Hotspots

'Bioquality' is a term which emphasies the global rarity of species in a community. Bioquality is measured using the Genetic Heat Index (GHI), to give a quantitative hotspot score for a community of plants. The bioquality of a plant community can be measured at any scale, from the very local to regional. Bioquality assessments make use of all available data. Typically, botanical records are drawn from herbaria, published checklists, dedicated surveys, formal plots and observations.

GHI is calculated by assigning each species in the project area a 'Star'. A Star is a category of global rarity. There are 4 Star categories. Black Star species are found in no more than 4 degree squares globally, and represent the world's most narrowly distributed plant species. Gold Star and Blue Star species are intermediate; Green Star species have the widest global distributions. Around 10% of the world's flora has a Star rating, including all tropical African taxa.

Bioquality assessments and Star ratings have been used to guide land use planning and conservation strategies all over the world.

Bioquality of Tropical Africa

RBS started with the Ghanaian surveys of the whole forest zone in the 1990s (Hawthorne and Abu Juam, 1995). We subsequently continued in West Africa with RBS' in Liberia, Sierra Leone, Guinea, Senegal and Cameroon.

Bioquality patterns can also be deduced at a broader scale, from general summaries of the flora in herbaria, monographs, floras and checklists. We are working towards a complete coverage of tropical Africa, at least at low (degree square) resolution, pending the opportunities to fill in local detail with RBS.

  • Cicely Marshall is investigating the patterns of Bioquality of Upper Guinea with reference to tropical Africa as a whole, as part of her D.Phil., and is compiling a database of locations and Stars for all vascular plant species. Cicely is investigating the phylogenetics of Upper Guinea species, to gain a better understanding of the evolution and significance of the Upper Guinea bioquality hotspots. A 2015 RBS field trip was made to SW Ghana, to fill in gaps in the bioquality gradient there established in outline by earlier surveys.

William Hawthorne is working with Cicely Marshall to develop the African Star-rating database; we are training teams in Africa to Survey particular regions; recently we have trained teams in Ethiopia, Cameroon and Malawi, and surveys there are either ongoing or recently completed.

  • Hawthorne, W.D. (1996). Holes and the sums of parts in Ghanaian forest: Regeneration, scale and sustainable use. Proceedings of the Royal Society of Edinburgh Section B: Biological Sciences. 104: pp 75-176.

  • Hawthorne, W.D, Abu-Juam, M. (1995). Forest Protection in Ghana (with particular reference to vegetation and plant species). doi:IUCN, Gland, Switzerland and Cambridge, U.K.

Bioquality of the Americas

RBS and bioquality assessment has previously been carried out in Mexico (Quintana Roo and Oaxaca), Honduras (Western coast) and Chile (Maule Region).

  • Gordon, J.E, Hawthorne, W.D, Reyes-Garcia, A, Sandoval, G, Barrance, A.J. (2004). Assessing landscapes: A case study of tree and shrub diversity in the seasonally dry tropical forests of Oaxaca, Mexico and southern Honduras . Biological Conservation 117 (4): pp 429-442. doi:10.1016/j.biocon.2003.08.011.

  • Gordon, J.E, Hawthorne, W.D, Sandoval, G, Barrance, A.J. (2003). Trees and farming in the dry zone of southern Honduras II: The potential for tree diversity conservation. Agroforestry Systems. 59 (2): pp 107-117. doi:10.1023/A:1026360205113.

Gail Stott is currently investigating the bioquality of Belize for her D.Phil., and is studying ways by which bioquality patterns might be predicted from limited data (e.g. tree data alone and distribution models).

The results of a Darwin Initiative RBS survey of Trinidad and Tobago has been published:

  • Yasmin S. Baksh-Comeau, Shobha S. Maharaj, C. Dennis Adams, Stephen A. Harris, Denis L. Filer, William D. Hawthorne (2016). An annotated checklist of the vascular plants of Trinidad and Tobago with analysis of vegetation types and botanical 'hotspots'. Phytotaxa, 250:1