Where have all the heathers gone?

Heathers have been cultivated for several centuries, both the hardy heaths (Calluna, Daboecia and Erica) from the northern hemisphere and the more frost-tender species of Erica from southern Africa known as Cape heaths. In the late 19th century, a number of heather gardens were created, especially in Britain, and the popularity of heathers as long-lasting garden plants reached its zenith in western Europe and temperate North America in the late 20th century. At about the same time, deliberate breeding and selecting of Calluna vulgaris (ling) for flowers that lack normal sexual parts and remain bud-like led to a revolution in heather production with tens of millions of these bud-bloomer Calluna propagated each year for an ephemeral trade dominated by throwaway plants. Concomitantly, the diversity of hardy heathers offered by the trade has declined sharply with a small number of artificially raised clones, protected by plant breeders’ rights, now dominating the market. In contrast, the discovery of living lineages of a few Erica species that are extinct in the wild in South Africa has led to successful reintroduction programmes, particularly of Erica verticillata. The Erica Conservation Consortium, inaugurated in 2020, aims to coordinate and prioritise ex situ conservation of endangered Cape heaths.publishedVersio

Fire, frost, and drought constrain the structural diversity of wood within southern African Erica (Ericaceae)

Erica comprises ~860 species of evergreen shrubs and trees ranged from Europe to southern Africa and Madagascar. Wood structure of the around 20 European species is well studied, but despite its relevance to adaptation across the wider geographic range, it has not yet been explored across the much greater diversity, particularly of southern African lineages. In this study, we examine wood structure of 28 Erica species from southern Africa. In the African Erica clade, loss of scalariform perforation plates could be driven by increased aridity and seasonality in the mid-Miocene, and its re-gain can represent an adaptation to freezing in the high elevation species E. nubigena. As vessels in Erica are mostly solitary, imperforate tracheary elements probably form a subsidiary conduit network instead of vessel groups. Increase of ray frequency in habitats with a prominent dry and hot season probably facilitates refilling of vessels after embolism caused by water stress. Wider rays are ancestral for the lineage comprising African Erica and the Mediterranean E. australis. The negative correlation between ray width and expression of summer drought is consistent with Ojeda’s model explaining the diversification of seeders and resprouters among southern African Erica.publishedVersio

Arboretets venner, aktiviteter og opplevelser 2019–2021

Friends of the Arboretum, activities and events 2019–2021. Moe & Pirie report from the Arboretum: seasonal events and highlights from the collections from 2019 to 2021, including an account of the Arboretum’s 50th anniversary. They document challenges presented by invasive species, diseases, and damage caused both by a cold winter in 2020/2021 and by unexpectedly high salt content of water taken from Mørkevatnet after a dry June in 2020. Finally, they detail and illustrate contributions to the gardens by voluntary work and support from the friends association (Arboretets venner), with thanks

An approach to determining anthocyanin synthesis enzyme gene expression in an evolutionary context: an example from Erica plukenetii

Background and Aims: Floral colour in angiosperms can be controlled by variations in the expression of the genes of the anthocyanin pathway. Floral colour shifts influence pollinator specificity. Multiple shifts in floral colour occurred in the diversification of the genus Erica (Ericaceae), from plesiomorphic pink to, for example, red or white flowers. Variation in anthocyanin gene expression and its effects on floral colour in the red-, pink- and white-flowered Erica plukenetii species complex was investigated. Methods: Next generation sequencing, reverse transcriptase PCR and real-time reverse transcriptase quantitative PCR were used to quantify anthocyanin gene expression. Key Results: Non-homologous mutations causing loss of expression of single genes were found, indicating that the cause was likely to be mutations in transcription factor binding sites upstream of the 5′-untranslated region of the genes, and this was confirmed by sequencing. Conclusions: Independent evolution and subsequent loss of expression of anthocyanin genes may have influenced diversification in the E. plukenetii species complex. The approach developed here should find more general application in studies on the role of floral colour shifts in diversification.acceptedVersio

History and evolution of the afroalpine fora: in the footsteps of Olov Hedberg

The monumental work of Olov Hedberg provided deep insights into the spectacular and fragmented tropical alpine flora of the African sky islands. Here we review recent molecular and niche modelling studies and re-examine Hedberg’s hypotheses and conclusions. Colonisation started when mountain uplift established the harsh diurnal climate with nightly frosts, accelerated throughout the last 5 Myr (Plio-Pleistocene), and resulted in a flora rich in local endemics. Recruitment was dominated by long-distance dispersals (LDDs) from seasonally cold, remote areas, mainly in Eurasia. Colonisation was only rarely followed by substantial diversification. Instead, most of the larger genera and even species colonised the afroalpine habitat multiple times independently. Conspicuous parallel evolution occurred among mountains, e.g., of gigantism in Lobelia and Dendrosenecio and dwarf shrubs in Alchemilla. Although the alpine habitat was ~ 8 times larger and the treeline was ~ 1000 m lower than today during the Last Glacial Maximum, genetic data suggest that the flora was shaped by strong intermountain isolation interrupted by rare LDDs rather than ecological connectivity. The new evidence points to a much younger and more dynamic island scenario than envisioned by Hedberg: the afroalpine flora is unsaturated and fragile, it was repeatedly disrupted by the Pleistocene climate oscillations, and it harbours taxonomic and genetic diversity that is unique but severely depauperated by frequent bottlenecks and cycles of colonisation, extinction, and recolonisation. The level of intrapopulation genetic variation is alarmingly low, and many afroalpine species may be vulnerable to extinction because of climate warming and increasing human impact.publishedVersio

Årsmeldinger for Universitetshagene 2019–2021

Annual reports for the Bergen University Gardens 2019–2021. The (annual) report of the Bergen University Gardens covers the years 2019–2021. It includes the gardens’ aims, organisation, personnel, partner organisations, and funding. A summary of research aims and activities includes published work, students, and external research. Teaching is described both at university level and for schools. Developments in the collections include important jubilees for each of the gardens, achievements in conservation, new accessions, and improvements to the infrastructure. Public communication includes numerous events, courses, digital resources, and information in the gardens. A full bibliography of peer reviewed publications and selected popular literature produced in the period is provided

Preventing species extinctions: A global conservation consortium for Erica

Societal Impact Statement Human-caused habitat destruction and transformation is resulting in a cascade of impacts to biological diversity, of which arguably the most fundamental is species extinctions. The Global Conservation Consortia (GCC) are a means to pool efforts and expertise across national boundaries and between disciplines in the attempt to prevent such losses in focal plant groups. GCC Erica coordinates an international response to extinction threats in one such group, the heaths, or heathers, of which hundreds of species are found only in South Africa's spectacularly diverse Cape Floristic Region. Summary Effectively combating the biodiversity crisis requires coordinated conservation efforts. Botanic Gardens Conservation International (BGCI) and numerous partners have established Global Conservation Consortia (GCC) to collaboratively develop and implement comprehensive conservation strategies for priority threatened plant groups. Through these networks, institutions with specialised collections and staff can leverage ongoing work to optimise impact for threatened plant species. The genus Erica poses a challenge similar in scale to that of the largest other GCC group, Rhododendron, but almost 700 of the around 800 known species of Erica are concentrated in a single biodiversity hotspot, the Cape Floristic Region (CFR) of South Africa. Many species are known to be threatened, suffering the immediate impacts of habitat destruction, invasive species, changes in natural fire regimes and climate change. Efforts to counter these threats face general challenges: disproportionate burden of in situ conservation falling on a minority of the community, limited knowledge of species-rich groups, shortfalls in assessing and monitoring threat, lack of resources for in situ and limitations of knowledge for ex situ conservation efforts and in communicating the value of biological diversity to a public who may never encounter it in the wild. GCC Erica brings together the world's Erica experts, conservationists and the botanical community, including botanic gardens, seed banks and organisations in Africa, Madagascar, Europe, the United States, Australia and beyond. We are collaboratively pooling our unique sets of skills and resources to address these challenges in working groups for conservation prioritisation, conservation in situ, horticulture, seed banking, systematic research and outreach.publishedVersio

Botaniske hager går sammen for å stanse utryddelsen av arter: Global Conservation Consortium for Erica (lyng)

Botanic gardens unite to prevent species extinctions: the Global Conservation Consortium for Erica. Michael Pirie et al. describe an international project to prevent extinctions of species of Erica, the heaths or heathers. The ‘Global Conservation Consortium for Erica’ is coordinated at the Bergen University Gardens under the umbrella of Botanic Gardens Conservation International (BGCI). The authors describe the challenges of understanding and protecting species rich plant groups where much of the diversity is concentrated in biodiversity hotspots. Around 700 Erica species are only found in South Africa’s Cape Floristic Region. They explain how GCC Erica will address those challenges, including through both ‘in situ’ and ‘ex situ’ conservation

Re-conceptualising Territorial Cohesion Through the Prism of Spatial Justice : Critical Perspectives on Academic and Policy Discourses

Peer reviewe