Near-natural forests in southern Sweden

Timber production and protection of biodiversity are two main issues in south Swedish forestry. This thesis explores the possibilities of combining the two issues in a nature-based silviculture. Different branches of science, palaeoecology, silviculture and forest vegetation ecology, were combined to give a multidisciplinary approach to the subject. Mimicking the historical forest composition and processes in the silvicultural measures for the benefit of both biodiversity protection and timber production was identified as one possible way of developing a nature-based silviculture. The long period of human influence on the landscape in southern Sweden has effectively removed all the remnants of natural forest that could have been used as references in the mimicking procedure. Consequently, historical references were searched. A method to describe former forest conditions was developed using palaeoecological data and methods. It was found that the historical deciduous dominance was pronounced. Over 2000 years southern Sweden has been transformed from a deciduous to a coniferous landscape. Human activities were shown to be a major driving force in this change. Several detected historical forest types were possible as references for the mimicking approach, but forest types common in the past and rare today were suggested for maximal efficiency in obtaining high biodiversity. Mixed nemoral deciduous forests were pointed out as a historically widespread forest type with very little resemblance in the present landscape. The small fragments left are important for present biodiversity and from many other aspects. Development of a nature-based silvicultural system for the management of mixed nemoral forest stands based on the theory of mimicking was begun. A silvicultural experiment was established in a near-natural, mixed nemoral forest stand in southern Sweden and the early effects of the silvicuitural treatments tested were evaluated with regard to floristic diversity. The early findings indicate that advance growth may be an effective source for regeneration of the forest type. Soil scarification is not recommended when regenerating mixed nemoral deciduous forest stands as the destruction of advance saplings was not compensated by new establishment, and because a tendency towards alteration of the ground flora typical of nemoral forest to a pioneer plant community was traced. Sparse shelterwood cutting is suggested as an appropriate way of combining biodiversity consideration and timber production in mixed nemoral deciduous forest stands. Finally, a framework of an approach to obtain a nature-based silvicultural system was developed, based on the presented results and other informatio

A late Quaternary pollen dataset from eastern continental Asia for vegetation and climate reconstructions: Set up and evaluation

A total of 271 pollen records were selected from a large collection of both raw and digitized pollen spectra from eastern continental Asia (70°−135°E and 18°−55°N). Following pollen percentage recalculations, taxonomic homogenization, and age–depth model revision, the pollen spectra were interpolated at a 500-year resolution and a taxonomically harmonized and temporally standardized fossil pollen dataset established with 226 pollen taxa, covering the last 22 cal ka. Of the 271 pollen records, 85% were published since 1990, with reliable chronologies and high temporal resolutions; of these, 50% have raw data with complete pollen assemblages, ensuring the quality of this dataset. The pollen records available for each 500-year time slice are well distributed over all main vegetation types and climatic zones of the study area, making their pollen spectra suitable for paleovegetation and paleoclimate research. Such a dataset can be used as an example for the development of similar datasets for other regions of the world