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BackgroundThe invasive weed species Gutenbergia cordifolia has been observed to suppress native plants and to dominate more than half of the entire crater floor (250 km2) in the Ngorongoro Conservation Area (NCA). As this species has been found to be toxic to ruminants it might strongly impact animal populations in this ecologically diverse ecosystem. Hence, a nature-based approach is urgently needed to manage its spread. We tested two Desmodium spp extracts applied to G. cordifolia and assessed the latter’s germination rate, height, fresh weight and leaf total chlorophyll content after 30 days in both laboratory and screen house experiments.ResultsSeedling germination rate was halved by Desmodium uncinatum leaf extract (DuL), particularly under higher concentrations (≥75 %) rather than lower concentrations (≤62.5 %). Likewise, in both laboratory and screen house experiments, germination rate under DuL treatments declined with increasing concentrations. Seedling height, fresh weight and leaf total chlorophyll content (Chl) were also most strongly affected by DuL treatments rather than D. uncinatum root extract, Desmodium intortum leaf extract or D. intortum root extract treatments. Generally, seedlings treated with higher DuL concentrations were half as tall, had one-third the weight and half the leaf Chl content compared to those treated with lower concentrations.ConclusionOur study shows a novel technique that can be applied where G. cordifolia may be driving native flora and fauna to local extinction. Our data further suggest that this innovative approach is both ecologically safe and effective and that D. uncinatum can be sustainably used to manage invasive plants, and thus, to improve rangeland productivity.

The information on the medicinal use, availability, challenges, and future conservation strategies for the medicinal plant Zanthoxylum chalybeum were gathered by using a semi-structured questionnaire, focused group discussions, and field observations in Simanjiro Area, Tanzania. Data were collected from local village members who were familiar with the tree and the key informants. Data were analyzed using Statistical Package for the Social Sciences (SPSS). The extent of use was found to be very high, with more than three-quarters of harvested parts used for treating women’s health system (86.4%). The most used plant parts for medicinal purposes were reported to be the roots and the stem bark (90.3% and 81.6%, respectively), possibly suggesting mortality caused by heavy harvesting. In addition to unsustainable harvesting methods, minimal and unpredictable propagation methods were the key factors affecting the recruitment rate, with perhaps an addition of continued climate and land-use change (93.2%), indicative of low precipitation and high agriculture and settlement expansions. Given these challenges, the future conservation and persistence of Z. chalybeum looks uncertain, which requires such measures as the provision of education and awareness and ensuring proper land-use plans that encompass active recruitment of the species in these areas.

PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism) analysis of cpDNA and PCR-RFLP of rDNA were performed to assess the phylogenetic relationship in seven species of the family Cornaceae. Four pairs of primers, trnD/trnT, trnH/trnK, psaA/trnS and rbcL/ORF106, and one restriction enzyme (HinfI) were used for RFLP-PCR of cpDNA, and two primer pairs ITS5/ITS2 and ITS3/ITS4 with one restriction enzyme (HhaI) were used for ITS1 and ITS2 regions of rDNA, successively. Restriction products produced by trnH/trnK-HinfI and psaA/trnS-HinfI for cpDNA and ITS5/ITS2-HhaI and ITS3/ITS4-HhaI for rDNA, generated very informative bands from all of the seven species studied. A total of 147 scores were recorded and used in PHYLIP (phylogeny inference package) to generate a combined phylogenetic tree. The family was divided into two clades: the Aucuba clade and the cornaceous clade. The cornaceous clade further divided into two subclades: the previously suggested blue-or white-fruited dogwoods (C. walteri and C. macrophylla) and the Cornelian cherries (C. officinalis), and the big-bracted dogwoods (C. kousa and C. florida). The opposite-leaved blue-or white-fruited dogwoods were found to be close sisters to the alternate-leaved blue-or white-fruited dogwoods and all sisters to the Cornelian cherries. C. kousa and C. florida were found to be close sisters under big-bracted dogwoods. Based on the topology portrayed by the phylogenetic tree obtained, it is possible to conclude that big-bracted dogwoods are the most primitive member followed by the intermediates -the cornelian cherries, and the blue-or white-fruited dogwoods are the most advanced members, while the Aucuba clade is the most primitive in the family.