4 research outputs found
Ex Situ Propagation of Philippine Rafflesia in the United States: Challenges and Prospects
The large-flowered parasitic genus Rafflesia R.Br. (Rafflesiaceae) has long fascinated naturalists and scientists and is an iconic symbol for plant conservation. Techniques to effectively propagate members of the genus outside of their natural habitat are sparse, and grafting infected Tetrastigma K.Schum.(Vitaceae) host plants has previously been reported as a successful strategy for ex situ conservation of Rafflesia. Here we report our attempts in the United States to propagate host cuttings infected with Rafflesia speciosa Barcelona & Fernando and R. lagascae Blanco collectedfrom the Philippines, as well as uninfected host material. We also describe efforts to germinate R. speciosa seeds in vitro using various plant growth regulators (PGRs). After rooting, infected host cuttings survived for a maximum of 11 months, but did not produce shoots. However, an uninfected cutting of T. cf. magnum grafted onto an established Malaysian species of Tetrastigma in June 2017 has succeeded in the commencement of new growth. Three propagules of a second potential host, T. harmandii Planch., have also been vigorously growing at the United States Botanic Garden since June 2017. However, Rafflesia seeds did not germinate with the application of PGRs, even though the seeds were viable according to tetrazolium (TZ) testing.These ex situ propagation attempts have revealed challenges in propagating these species outside of their native ranges, but our incremental success in rooting infected Tetrastigma, as well as grafting interspecific Tetrastigma species, bodes well for further advances. With Philippine host species, T. harmandii and T. cf. magnum in cultivation, we can begin using these specimens for future experimentation involving grafting of infected material and Rafflesia seed inoculation trials.Furthermore, we describe new avenues of propagation techniques for Rafflesia as practised by Marius Gabin, one of the owners of the Vivian Rafflesia garden, which contains a natural Rafflesia forest habitat at Poring Springs, Sabah, Malaysia. Gabin openly shared his successes in artificially inoculating Rafflesia seeds into a mature Tetrastigma vine. Gabin’s willingness to share his experience highlights the importance of collaborating with practitioners who have developed local knowledge of Rafflesia horticulture and conservation
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The 1430s: a cold period of extraordinary internal climate variability during the early Spörer Minimum with social and economic impacts in north-western and central Europe
Changes in climate affected human societies throughout the last millennium. While European cold periods
in the 17th and 18th century have been assessed in detail, earlier cold periods received much less attention due to sparse information available. New evidence from proxy archives, historical documentary sources and climate model simulations permit us to provide an interdisciplinary, systematic assessment of an exceptionally cold period in the 15th century. Our assessment includes the role of internal, unforced climate variability and external forcing in shaping extreme climatic conditions and the impacts on and responses of the medieval society in north-western and central Europe. Climate reconstructions from a multitude of natural and anthropogenic archives indicate that the 1430s were the coldest decade in north-western and central Europe in the 15th century. This decade is characterised by cold winters and average to warm summers resulting in a strong seasonal cycle in temperature. Results from comprehensive climate models indicate consistently that these conditions occurred by chance due to the partly chaotic internal variability within the climate system. External forcing like volcanic eruptions tends to reduce simulated temperature seasonality and cannot explain the reconstructions. The strong seasonal cycle in temperature reduced food production and led to increasing food prices, a subsistence crisis and a famine in parts of Europe. Societies were not prepared to cope with failing markets and interrupted trade routes. In response to the crisis, authorities implemented numerous measures of supply policy and adaptation such as the installation of grain storage capacities to be prepared for future food production shortfalls