Browsing by Subject "Eastern Arc Mountains"

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  • Zilihona, I.J.E.; Niemelä, J.; Nummelin, M. (Kluwer Academic Publishers, 2004)
    The effects of river flow diversion on biodiversity were assessed using Coleoptera as an indicator group in three habitats of the Kihansi Gorge (Udzungwa Mountains, Tanzania), before and after commissioning of a hydropower plant. Data collected using sweep netting and pitfall traps showed that the effect of diversion of the river flow was site-specific, affecting particularly the spray habitat. Rarefaction analysis of both sweep netting and pitfall samples indicated that the expected richness of Coleoptera declined significantly in all habitats after commissioning of the power plant. Sweep netting and pitfall samples showed that the highest Shannon-Wiener diversity index value before the diversion of the river flow was in the spray zone, but the index value decreased after diversion. Changes in the other two habitats were less prominent. Analysis of variance using diversity index values from five pitfall samples in each habitat type before and after commissioning indicated that there were no statistically significant differences in the diversity index between the two sampling periods or among the three habitat types. Renkonen's similarity index between habitats showed that pitfall samples had higher similarity (87%) than did samples from sweep netting (69%). It is suggested that for mitigation purposes, artificial spray systems, which have been installed in other wetlands of the Kihansi Gorge, also be installed to cover the whole Lower Wetland in which this study was undertaken. In order to maintain overall biodiversity in the Kihansi Gorge, it is suggested that the ecosystem conservation approach be prioritised.
  • Kantelinen, Annina; Hyvärinen, Marko; Kirika, Paul; Myllys, Leena (2021)
    The genus Micarea was studied for the first time in the Taita Hills, Kenya. Based on new collections and existing data, we reconstructed a phylogeny using ITS, mtSSU and Mcm7 regions, and generated a total of 27 new sequences. Data were analyzed using maximum likelihood and maximum parsimony methods. Based mainly on new collections, we discovered four undescribed well-supported lineages, characterized by molecular and phenotypic features. These lineages are described here as Micarea pumila, M. stellaris, M. taitensis and M. versicolor. Micarea pumila is characterized by a minutely granular thallus, small cream-white or pale brownish apothecia, small ascospores and the production of prasinic acid. Micarea stellaris has a warted-areolate thallus, cream-white apothecia usually darker at the centre, a hymenium of light grey or brownish pigment that dissolves in K, and intense crystalline granules that appear as a belt-like continuum across the lower hymenium when studied in polarized light. Micarea taitensis is characterized by a warted-areolate thallus and cream-white or yellowish apothecia that sometimes produce the Sedifolia-grey pigment. Micarea versicolor is characterized by a warted-areolate, sometimes partly granular thallus and apothecia varying from cream-white to light grey to blackish in colour. This considerable variation in the coloration of its apothecia is caused by an occasional mixture of the Sedifolia-grey pigment in the epihymenium and another purplish brown pigment in the hymenium. Micarea stellaris, M. taitensis and M. versicolor produce methoxymicareic acid. The main distinguishing characters are presented in a species synopsis. Three of the new species are nested in the M. prasina group, and the fourth one (M. taitensis) resolves as a basal taxon to the M. prasina group. The new species inhabit montane cloud forests, which have fragmented dramatically throughout the Eastern Arc Mountains in recent decades.
  • Aben, Job; Bocedi, Greta; Palmer, Stephen C. F.; Pellikka, Petri; Strubbe, Diederik; Hallmann, Caspar; Travis, Justin M. J.; Lens, Luc; Matthysen, Erik (2016)
    As biodiversity hotspots are often characterized by high human population densities, implementation of conservation management practices that focus only on the protection and enlargement of pristine habitats is potentially unrealistic. An alternative approach to curb species extinction risk involves improving connectivity among existing habitat patches. However, evaluation of spatially explicit management strategies is challenging, as predictive models must account for the process of dispersal, which is difficult in terms of both empirical data collection and modelling. Here, we use a novel, individual-based modelling platform that couples demographic and mechanistic dispersal models to evaluate the effectiveness of realistic management scenarios tailored to conserve forest birds in a highly fragmented biodiversity hotspot. Scenario performance is evaluated based on the spatial population dynamics of a well-studied forest bird species. The largest population increase was predicted to occur under scenarios increasing habitat area. However, the effectiveness was sensitive to spatial planning. Compared to adding one large patch to the habitat network, adding several small patches yielded mixed benefits: although overall population sizes increased, specific newly created patches acted as dispersal sinks, which compromised population persistence in some existing patches. Increasing matrix connectivity by the creation of stepping stones is likely to result in enhanced dispersal success and occupancy of smaller patches.Synthesis and applications. We show that the effectiveness of spatial management is strongly driven by patterns of individual dispersal across landscapes. For species conservation planning, we advocate the use of models that incorporate adequate realism in demography and, particularly, in dispersal behaviours.