580 Pflanzen (Botanik)
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Positive plant–plant interactions are thought to drive vegetation patterns in harsh environments, such as semi-arid areas. According to the stress-gradient hypothesis (SGH), the role of positive interactions between species (facilitation) is expected to increase with harshness, predicting associated variation in species composition along environmental gradients. However, the relation between stress and facilitation along environmental gradients is debated. Furthermore, differentiating facilitative interactions from other underlying mechanisms, such as microtopographic heterogeneity, is not trivial. We analysed the spatial co-occurrence relationships of vascular plant species that form patchy vegetation in arid lapilli fields (tephra) from recent volcanic eruptions on La Palma, Canary Islands. Assuming a harshness gradient negatively correlated with elevation because the lower elevations are more arid and water availability is considered the most limiting resource, and that an outcome of facilitation is plants co-occurring in the same patch, from the SGH we expected a greater degree of co-occurrence at lower elevation. We tested this at both the species and the individual plant level. We analysed the species composition of 1277 shrubby vegetation patches at 64 different sampling points, ranging from the coast to around 700 m a.s.l. Patch morphology and microtopographic heterogeneity variables were also measured, to account for their potential effects on the species composition of patches. We used generalized linear models and generalized mixed-effects models to analyse species richness, number of individuals in patches and percentage of patches with positive co-occurrences, and a pairwise co-occurrence analysis combined with a graphical network analysis to reveal positive links between 13 of the species. We found that the percentage of patches with positive co-occurrences increased at higher elevations, in contrast to the predictions of the SGH, but in accordance with a refined stress-gradient hypothesis for arid sites, in which characteristics of the interacting species are incorporated.
We present a preliminary discussion about cauliflory, sexual dimorphism and biogeographic patterns in Drypetes Vahl (Putranjivaceae Endl.), focused on Africa. We also present a taxonomic treatment for two new species of cauliflorous trees of this genus from the rainforests of western Central Africa, one endemic to Gabon and known from six gatherings, D. aphanes Quintanar, D.J.Harris & Barberá sp. nov., and the other distributed in Gabon and the Republic of the Congo, D. cauta D.J.Harris, Barberá & Quintanar sp. nov., also known from another six gatherings. They are presented along with D. gabonensis Pierre ex Hutch., known from 25 gatherings made throughout western Central Africa, a species with markedly dimorphic flowers between sexes compared to the rest of the species in the genus. Specimens of these two new species have been confused with D. gabonensis due to some morphological resemblances. This treatment includes the detailed descriptions of these three species, the typification of their names, a comparative table summarizing their main morphological differences, an identification key, an illustration and information about their habitat and distribution. A provisional IUCN Red List assessment shows that D. gabonensis and D. cauta sp. nov. are ‘Vulnerable’ species, and D. aphanes sp. nov. is ‘Endangered’. After the publication of these new species, Drypetes consists of 86 species in continental Africa and the Malagasy Region and 219 species for the whole world.
Merianthera is a genus of flowering plants with up to now seven species occurring in eastern Brazil, in the states of Bahia, Espírito Santo, and Minas Gerais. It belongs to the tribe Pyramieae (Melastomataceae), and can be recognized by its shrubby or treelet habit with caducous leaves, 5-merous flowers with a strongly zygomorphic androecium, the latter with dimorphic stamens bearing complex dorsal connective appendages, as well as an inferior ovary and capsular fruits. We describe here a new species of Merianthera from two collections and a photographic record, all from the same locality, an inselberg in the Municipality of Jacinto, in northeastern Minas Gerais. Its candelabriform habit, with a fistulose stem, and solitary, axillary or cauliflorous flowers are only shared with M. burlemarxii. However, M. calyptrata R.Goldenb., Bochorny & Fraga sp. nov. has at least three characters that are absent in M. burlemarxii and all other species in the genus: the total absence of both a peduncle and bracteoles, the calyptrate calyx and the fruits developing from inferior ovaries and dehiscing through longitudinal slits. The first character appears to be unknown in other species in the family.
We provide a floristic account for the Begoniaceae of Peru. The family is represented in Peru by 76 species, which are all members of the genus Begonia and represent eighteen sections. Twelve new species are described: B. condorensis Jara & Moonlight sp. nov., B. deltoides Moonlight sp. nov., B. huancabambae Moonlight sp. nov., B. imbrexiformis Moonlight sp. nov., B. longinqua Moonlight sp. nov., B. longitepala Moonlight sp. nov., B. nunezii Moonlight sp. nov., B. occultata J.P.Allen & Moonlight sp. nov., B. pedemontana Moonlight sp. nov., B. serratistipula Moonlight sp. nov., B. vargasii Moonlight sp. nov. and B. yuracyacuensis Moonlight sp. nov. We also provide four new records for the country: B. andina Rusby, B. brandbygeana L.B.Sm. & Wassh., B. neoharlingii L.B.Sm. & Wassh. and B. unilateralis Rusby. We provide an identification key to all species. The ecology, distribution, and conservation status of all Peruvian Begonia species are discussed, including provisional IUCN threat assessments. Most species are illustrated by either historical illustrations, contemporary photographic plates, or line drawings. Twenty-six names are newly synonymised including fifteen previously accepted species, and we designate eighty-three lectotypes, four neotypes, and four epitypes.
In search for practical silvicultural management tools to identify alternative tree species for predicted Central European climate conditions, a cross-species survey with five evergreen, semi-evergreen, and deciduous Quercus taxa with contrasting morphological leaf traits was performed. Fast chlorophyll fluorescence induction of PSII and relative leaf chlorophyll contents were performed to assess the overall plant vitality at any point in time during two complete vegetation periods in consecutive years (2012 and 2013). Maximum photochemical efficiency of PSII and the performance index on absorption base showed a very conservative relationship to each other and a similar intra-annual progress in all deciduous species, but with a different speed of increase and decrease during leaf development and senescence and thus a different length of vegetation period. The intra-annual variability of OJIP and chlorophyll content parameters is considered with respect to the practicability of measurements in the field for management purposes.
The European Beech is the dominant climax tree in most regions of Central Europe and valued for its ecological versatility and hardwood timber. Even though a draft genome has been published recently, higher resolution is required for studying aspects of genome architecture and recombination. Here, we present a chromosome-level assembly of the more than 300 year-old reference individual, Bhaga, from the Kellerwald-Edersee National Park (Germany). Its nuclear genome of 541 Mb was resolved into 12 chromosomes varying in length between 28 and 73 Mb. Multiple nuclear insertions of parts of the chloroplast genome were observed, with one region on chromosome 11 spanning more than 2 Mb which fragments up to 54,784 bp long and covering the whole chloroplast genome were inserted randomly. Unlike in Arabidopsis thaliana, ribosomal cistrons are present in Fagus sylvatica only in four major regions, in line with FISH studies. On most assembled chromosomes, telomeric repeats were found at both ends, while centromeric repeats were found to be scattered throughout the genome apart from their main occurrence per chromosome. The genome-wide distribution of SNPs was evaluated using a second individual from Jamy Nature Reserve (Poland). SNPs, repeat elements and duplicated genes were unevenly distributed in the genomes, with one major anomaly on chromosome 4. The genome presented here adds to the available highly resolved plant genomes and we hope it will serve as a valuable basis for future research on genome architecture and for understanding the past and future of European Beech populations in a changing climate.
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(2023)
Campanula cervicaria steht in Hessen kurz vor dem Aussterben und wurde im Rahmen des Kooperationsvertrages zwischen der Botanischen Vereinigung für Naturschutz in Hessen (BVNH) und dem Land Hessen untersucht. Das Ziel der Untersuchung war, herauszufinden wo Campanula cervicaria in Hessen noch vorkommt und wie groß die Populationen sind. In Hessen sind aktuell noch 20 Populationen vorhanden. Fast 90 % der Populationen befinden sich in der Umgebung von Lißberg, Hirzenhain und Gedern im Westlichen Unteren Vogelsberg. Zwei weitere liegen bei Jossa im Spessart und bei Ober-Gleen im Nördlichen Vogelsberg-Vorland. Die größte Population befindet sich an der Kreisstraße 216 bei Hirzenhain am Forsthaus Luisenlust. Campanula cervicaria wächst in Hessen an sonnenexponierten Wegböschungen und Windwurfflächen, meist zusammen mit Hypericum hirsutum und Brachypodium sylvaticum. Um auch zukünftig die Bestände von Campanula cervicaria zu sichern, müsste ein Artenhilfskonzept erarbeitet werden.