Developing conservation strategies for endemic tree species when faced with time and data constraints: Boswellia spp. on Socotra (Yemen)

Abstract

Many endemic tree species have important scientific, ecological and economic value but the scarcity of information about their biological and ecological features makes it difficult to develop conservation strategies for them. A four-step approach is presented to address this problem, based on the analysis of data collected in a limited-duration field study: (1) Data collected are used to analyse the ecological niche, population structure and regeneration status of the species in question. (2) Several IUCN Red List (RL) parameters, useful for assessing the species' risk of extinction, are measured, including population counts, number of locations, extent and area of occurrence. (3) The IUCN RL parameters are used together with the other information gathered to set preliminary conservation priorities. (4) The analysis of utilization pattern is used to develop conservation actions specific to the environmental and socio-economic context. To test the applicability of this approach Boswellia spp. of Socotra island were analysed. Ground-rooted species (B. ameero, B. elongata and B. socotrana) were the most abundant and widespread and, according to the spatial analysis, were characterised by a geo-altitudinal zonation. However, the Weibull functions fitted on their stem diameters, and the absence or presence of only a small number of saplings highlighted a poor regeneration status. In the absence of conservation actions, these species will probably be subject to a progressive decline because of uncontrolled grazing. Of the four cliff-rooted species, which grow in sites that are less accessible to livestock, two (B. popoviana and B. dioscorides) were of lower conservation priority and may become the most numerically abundant. Conversely, the other two (B. nana and B. bullata), which may be threatened by stochastic events because of their reduced populations and small number of locations, were considered of very high priority. Different conservation actions were then identified for each species. In particular, for Boswellia species producing gum, the conservation-through-use action was discussed as a potential option

Geographical distance and barriers explain population genetic patterns in an endangered island perennial

“…Since the species shows a considerable degree of genetic diversity, high seed production and high germination rate (Dias et al . 2015), some of the conservation actions that should be implemented or established are: (i) running a seed bank and a plant nursery (Attorre et al . 2011), where plants from the different islands could be produced following specific protocols for L. watsoniana (Dias et al .…”

Volatile Compounds in Oleo-gum Resin of Socotran Species of Burseraceae

“…The oleo-gum resin of endemic species of frankincense and myrrh trees is locally used (Miller, et al, 2004) and could become a relatively important export article for Socotra Island. The oleo-gum resin harvesting could increase the interest of local people in artificial reforestation and plantation (Lvončík, et al, 2013) of the endangered endemic Boswellia (Attorre, et al, 2011) and Commiphora species and thereby improve the protection and rescue of its populations. However, in such case we recommend to Yemeni state structure to introduce strict rules for plantation certification and thoroughly implement their adherence in order to prevent the risk of plunder of residual populations (Scholte, et al, 2011).…”

“…No herbarium specimens were not taken from any of the sample trees, because the island belongs to the UNESCO Biosphere Reserve, from which exportation of any natural product is strictly prohibited. Moreover, the endemic Boswellia and Commiphora species are mostly strongly threatened (Attorre, et al, 2011;Miller, et al, 2004), and their disturbance is undesirable. Therefore, instead photo-documentation was used.…”

Impact of alternative metrics on estimates of extent of occurrence for extinction risk assessment

“…Others have used alpha hull algorithms, which provide an objective method of excluding discontinuities in the species range (e.g., Burgman & Fox ; Attorre et al. ). However, many assessments (e.g., all 10,039 bird species and most of the >5,000 mammal species on the IUCN Red List) have calculated EOO by summing the area of all polygons in the species extant distribution map; these polygons excluded areas within the geographic distribution of a species that were not considered habitat.…”