Experimental transplants reveal strong environmental effects on the growth of non‐vascular epiphytes in Afromontane forests

Transplant studies can provide valuable information on the growth responses of epiphytic bryophytes and lichens to environmental factors. We studied the growth of six epiphyte species at three sites in moist Afromontane forests of Taita Hills, Kenya. With 558 pendant transplants, we documented the growth of four bryophytes and two lichens over 1 yr. The transplants were placed into the lower canopy of one forest site in an upper montane zone, and two forest sites in a lower montane zone. Several pendant moss species grew very well in the cool and humid environment of the upper montane forest, with some transplants more than doubling their biomass during the year. Conversely, all transplanted taxa performed poorly in the lower montane zone, presumably because of the unfavorable combination of ample moisture with excessive warmth and insufficient light which characterizes the lower canopy in dense lower montane forests. The results demonstrate that pendant transplants can be used for monitoring growth of non‐vascular epiphytes in tropical forests. The starting weight of 0.25 g for pendant transplants worked well and can be recommended for future studies.     

Classification of Prosopis juliflora invasion in the Lake Baringo basin and environmental correlations

The spread of Prosopis juliflora in the Baringo basin, Kenya, has led to severe changes in the ecosystem with negative socio‐economic impacts. The drivers that foster the invasiveness of Prosopis are not fully understood. Thus, a method to quantify the degree of infestation will support the determination of environmental preferences and the risk assessment of future Prosopis invasion. We developed a methodology for characterising and classifying degrees of Prosopis infestation in vegetation stands and propose its application in environmental correlation models. The relative cover was identified as the most suited attribute for assessing and monitoring the invasion of Prosopis. The distance of invaded stands from original plantations and environmental attributes related to water availability (ground water table, rainfall and soil water–holding capacity) have potential to predict potential or future invasion risks.     

Multiple Pleistocene refugia and recent diversification for Streptocarpus ionanthus (Gesneriaceae) complex: Insights from multiple molecular sources

Streptocarpus ionanthus (Gesneriaceae) is endemic to Tanzania and Kenya, distributed in Tanga, Morogoro, and Kilifi regions. The species houses nine subspecies characterized by complex morphotypes and poorly understood evolutionary relationships, and thus is an ideal model for investigating evolutionary dynamics over time. Using multiple methods, we sought to test our hypothesis that the infraspecific taxa in Str. ionanthus are slightly variable and evolving populations. We first examined the genetic diversity, population differentiation, and phylogeographic structure among the populations of Str. ionanthus using both chloroplast and nuclear markers. We then estimated the divergence time of Str. ionanthus lineages and modeled past and future distribution. Despite Str. ionanthus exhibiting bottleneck events across its range, the populations maintain relatively high genetic diversity attributed to historical population admixture or local adaptation arising from habitat heterogeneity. The phylogeographic and genetic structure revealed a high connection among the Usambara mountains populations, while molecular dating suggested most diversification of haplotypes began ~1.32–0.18 million years ago and intensified toward the present, a conclusion of recent diversification. Phylogenetic relationship of Str. ionanthus cpDNA haplotypes revealed five main lineages with unique haplotypes that could be suggestive of past isolated refugia during the Pleistocene climate shifts. According to niche modeling, the stability of suitable areas during the Last Glacial Maximum (LGM) offered protective micro-habitats that have preserved the genetic diversity of Str. ionanthus to date. In conclusion, our findings suggest a complex Str. ionanthus with slightly variable lineages or populations attributed to multiple refugia and on the verge of divergence.     

<Emphasis Type="Italic">Barleria compacta</Emphasis>: a new species in <Emphasis Type="Italic">Barleria</Emphasis> sect. <Emphasis Type="Italic">Prionitis</Emphasis> (Acanthaceae) from Somalia

Following a re-examination of the material treated under Barleria brevispina (Fiori) Hedrén in the recent Flora of Somalia account of the Acanthaceae, it is concluded that two distinct species are involved and Barleria compacta Malombe & I. Darbysh. is described here from north-eastern Somalia. Its affinities and conservation status are discussed.