The development and demise of a Medieval forest-meadow system at Linnaeus' birthplace in southern Sweden: implications for conservation and forest history

The rapid industrialisation of agriculture and forestry during the last century has contributed to a transformation of the forested landscape in southern Sweden. Palaeoecological investigation revealed how the Medieval forest-meadow system was created about 900 years ago from a deciduous forest type that had been rather stable for the previous 3000 years. The study site was a forest hollow close to where Linnaeus was born and brought up. The species-rich forest-meadow system suffered from over-grazing during the human-population peak of the nineteenth century, and was abandoned about one hundred years ago. The recent forest succession in southern Sweden has led to reduced floristic biodiversity and created conservation problems related to disappearance of open landscape, even though the remnant vegetation is moving towards the near-natural forest type. Spatially detailed palaeoecology permits documentation of baseline conditions, and places conservation debates in a valuable temporal perspective.     

Close anthropogenic control of Fagus sylvatica establishment and expansion in a Swedish protected landscape – implications for forest history and conservation

Aim The dominant forces behind the expansion of Fagus sylvatica (beech) in northern Europe during the late Holocene have been much debated. Palaeoecological analyses were performed for a biodiversity hotspot reserve in order to study the processes behind the local establishment of Fagus, as well as the historical vegetational development in relation to present‐day biodiversity and conservation. Location Biskopstorp Forest Reserve in south‐west Sweden. Methods Pollen and charcoal were analysed from three small‐hollow sites in the reserve. Two of the investigated wetlands were located adjacent to old‐growth stands of Fagus, and the third was located near a stand of old Quercus. Results The 2500‐year record shows that Fagus was first established around the two Fagus old‐growth sites, c. ad 900 and 1200, respectively, and that this was followed by an expansion around ad 1600. During the establishment phase, and more so in the expansion phase, there were simultaneous increases in types of pollen indicative of human activity. These indicators are also frequent throughout the record from the Quercus site, but here Fagus never became common. Main conclusions The dynamics behind the establishment and expansion of Fagus in the reserve seems to have been influenced to a large degree by human activity, for example selective cutting, human‐induced fires, and agriculture. Fagus became established in the reserve more than 1000 years after it became established regionally, making climate less probable as the dominant force behind the species’ stand‐scale establishment. The spreading of Fagus across southern Scandinavia has previously been shown to be a patchy process in time and space. Our study suggests that this patchiness is evident also at a small spatial scale (a few kilometres). At the Quercus site, relatively high amounts of pollen from the field layer throughout the record indicate open conditions that probably favoured Quercus. The degree of human impact at this site was probably too high to allow the expansion of Fagus. With the long‐term perspective provided by our study it was possible to identify the last 200–300 years as an unrepresentative period with respect to tree species composition and forest dynamics. The large increase of Picea locally and regionally over the last several hundred years, combined with dramatic levels of human impact, have altered the tree composition and forest dynamics to such an extent that active management is necessary in order to maintain biodiversity in the reserve.     

Comparison of the performance of a hollow-fiber microbe reactor with a reactor containing alginate entrapped cells

Summary Alginate entrapped Pseudomonas denitrificans have been compared with cells confined in the outer space of a hollow-fiber membrane unit with respect to continuous denitrification of water. The hollow-fiber unit had a higher productivity as well as a stability similar to that of the alginate unit. A reduction of cell-leakage in the eluate was found in the hollow-fiber unit. The nitrogen gas produced could be removed by circulating the cell containing fluid over a hydrophobic membrane.     

Conditional Markov Chain Design for Accrual Clinical Trials

Randomization in a comparative experiment has, as one aim, the control of bias in the initial selection of experimental units. When the experiment is a clinical trial employing the accrual of patients, two additional aims are the control of admission bias and control of chronologic bias. This can be accomplished by using a method of randomization, such as the “biased coin design” of Efron, which sequentially forces balance. As an extension of Efron's design, this paper develops a class of conditional Markov chain designs. The detailed randomization employed utilizes the sequential imbalances in the treatment allocation as states in a Markov process. Through the use of appropriate transition probabilities, a range of possible designs can be attained. An additional objective of physical randomization is to provide a model for data analysis. Such a randomization theoretic analysis is presented for the current designs. In addition, Monte Carlo sampling results are given to support the proposed normal theory approximation to the exact randomization distribution.     

The influence of former land-use on vegetation and biodiversity in the boreo-nemoral zone of Sweden

Pollen analyses were carried out at two sites with contrasting land-use histories (in-field and out-land) within a single estate. The aim was to distinguish the relative importance of natural processes and cultural influence on the development of vegetation and biodiversity. The estate lies in the boreo-nemoral zone of southern Sweden, and attention is focused on the distribution of coniferous and deciduous trees. The in-fields. which lie close to the estate buildings, are currently dominated by deciduous trees, and have a documented history as fields and hay meadows. The more distant out-lands were primarily used as grazing land in the past, and support coniferous forest at present. The study covers the last 4000 yr, 2000–1000 BC: the out-lands site supported natural, dense forests consisting of Quercus, Betula, Tilia, Alnus and Corylus. 1000 BC–AD 1100: several events are best interpreted as an increased cultural activity in the area. Agriculture was based on animal husbandry and the recorded cereals probably originate from a kind of shifting cultivation. AD 1000–1800: agriculture intensified on the in-fields with cereal cultivation of increased importance, while the out-fields were used for slash-and-burn agriculture and forest grazing. The forests became more open in structure but the composition remained unchanged. An increase in Colluna was a possible consequence of over-exploitation, AD 1800 onwards: the out-field deciduous forests were rapidly replaced by Picea-Pinus coniferous forests during the l800's. The in-fields retained deciduous forest with a continuity of Quercus and other species. There is a close, positive relationship between floristic diversity and cultural influence during the last 4000 yr. A comparison is made with a similar investigation on another estate in the region, revealing small differences between the estates, but striking similarities in the effects of land-use types on the development of vegetation. The significance of former in-fields for nature conservation is discussed, particularly as a potential source for increasing the deciduous component in commercial forestry practice.