3 research outputs found
Dryland tree data for the Southwest region of Madagascar: alpha-level data can support policy decisions for conserving and restoring ecosystems of arid and semiarid regions
We present an eco-geographical dataset of the 355 tree species (1 56 genera, 55 families) found in the driest coastal portion of the spiny forest-thickets of southwestern Madagascar. This coastal strip harbors one of the richest and most endangered dryland tree floras in the world, both in terms of overall species diversity and of endemism. After describing the biophysical and socio-economic setting of this semiarid coastal region, we discuss this regionâs diverse and rich tree flora in the context of the recent expansion of the protected area network in Madagascar and the growing engagement and commitment to ecological restoration. Our database, DTsMada (short for Desert Trees of Madagascar), is part of a larger âwork-in-progressâ, namely an eco-geographical database on desert and dryland trees of the world. DTsMada draws heavily on the Catalogue of the Vascular Plants of Madagascar (MadCat) project, in which floristic, ecological and endemism parameters are compiled, together with available conservation status assessments based on IUCN Red List criteria. Both are projects within the plant systematics database, TropicosÂź, developed at Missouri Botanical Garden and maintained on the Gardenâs website. To highlight the need for greater study of the interactions between biological, bioclimatic, and anthropogenic determinants of current and potentially changing biogeographical patterns and community dynamics in the tree strata of vegetation in the study area, we consider four contrasting groups of native trees: Adansonia spp. (Malvaceae), Pachypodium spp. (Apocynaceae), Baudouinia spp. (Fabaceae), and all 1 1 species in the 4 genera of Didiereaceae in Madagascar. We discuss DTsMada as a prototype dataset of alpha level information vital for effective conservation, landscape planning, sustainable use and management, and ecological restoration of degraded arid and semiarid ecosystems, in Madagascar and elsewhere. RĂSUMĂNous prĂ©sentons un ensemble de donnĂ©es Ă©co-gĂ©ographiques sur les 355 espĂšces dâarbres (1 56 genres, 55 familles) prĂ©sentes dans les fourrĂ©s et forĂȘts Ă©pineux de la frange cĂŽtiĂšre aride et semiaride du Sud-ouest de Madagascar. Cette rĂ©gion possĂšde un des assemblages dâarbres de climat sec les plus riches (en termes de diversitĂ© spĂ©cifique et dâendĂ©misme), et les plus menacĂ©s au monde. AprĂšs une description du cadre biophysique et de la situation socio-Ă©conomique de cette rĂ©gion, nous prĂ©sentons cette flore rĂ©gionale dans le contexte de la rĂ©cente expansion du rĂ©seau de des aires protĂ©gĂ©es de Madagascar et de lâengagement croissant dans le domaine de la restauration Ă©cologique. Notre base de donnĂ©es DTsMada (raccourci de «d Desert Trees - Madagascar d », en anglais) sâinscrit dans le cadre dâune base de donnĂ©es éco-gĂ©ographique plus large que nous dĂ©veloppons, regroupant les espĂšces dâarbres des rĂ©gions arides et semiarides du monde entier, avec un accent particulier mis sur leur utilisation dans la conservation, gestion et restauration Ă©cologique. Nombre des informations prĂ©sentĂ©es dans DTsMada proviennent du projet MadCat (Catalogue des plantes vasculaires de Madagascar) qui regroupe des donnĂ©es floristiques et Ă©cologiques, et les statuts dâendĂ©misme et de conservation des espĂšces vĂ©gĂ©tales, basĂ©s sur les critĂšres de lâUICN. Ces deux projets font partie de la base de donnĂ©es taxonomique TropicosÂź, du Jardin Botanique du Missouri. Pour souligner le besoin de disposer de plus dâĂ©tudes pour comprendre d : les interactions entre les facteurs biologiques, bioclimatiques et anthropiques qui affectent la biogĂ©ographie et les dynamiques des communautĂ©s dans les strates arborĂ©es de la vĂ©gĂ©tation dans la rĂ©gion Ă©tudiĂ©e, quâil sâagisse de la situation actuelle ou celle dâun futur qui sera Ă©ventuellement modifiĂ©, nous considĂ©rons quatre groupes bien diffĂ©rents dâespĂšces dâarbres indigĂšnesd : Adansonia spp. (Malvaceae), Pachypodium spp. (Apocynaceae), Baudouinia spp. (Fabaceae) et les 1 1 espĂšces dans les 4 genres de la famille des Didiereaceae du Sud-ouest de Madagascar. Nous traitons DTsMada comme prototype dâune base de donnĂ©es de niveau alpha, vitales pour la conservation, la planification, le dĂ©veloppement durable, la gestion et la restauration Ă©cologique des Ă©cosystĂšmes arides et semiarides de Madagascar et dâailleurs
Identification of priority areas for plant conservation in Madagascar using Red List criteria: rare and threatened Pandanaceae indicate sites in need of protection
A major problem in establishing effective protocols for conserving Madagascar's biodiversity is the lack of reliable information for the identification of priority sites in need of protection. Analyses of field data and information from herbarium collections for members of the plant family Pandanaceae (85 spp. of Pandanus; 6 spp. of Martellidendron) showed how risk of extinction assessments can inform conservation planning. Application of IUCN Red List categories and criteria showed that 91% of the species are threatened. Mapping occurrence revealed centres of richness and rarity as well as gaps in Madagascar's existing protected area network. Protection of 10 additional sites would be required to encompass the 19 species currently lacking representation in the reserve network, within which east coast littoral forests are particularly under represented and important. The effect of scale on assessments of risk of extinction was explored by applying different grid cell sizes to estimate area of occupancy. Using a grid cell size within the range suggested by IUCN overestimates threatened status if based solely upon specimen data. For poorly inventoried countries such as Madagascar measures of range size based on such data should be complemented with field observations to determine population size, sensitivity to disturbance, and specific threats to habitat and therefore potential population decline. The analysis of such data can make an important contribution to the conservation planning process by identifying threatened species and revealing the highest priority sites for their conservatio