Jennifer Sjölund

PhD Research Student

MRes Ecology & Environmental Sustainability, University of Aberdeen (2010)
BSc (Hons) Biological Sciences, London Metropolitan University (2009)

Supervisor: Prof Alistair Jump, University of Stirling

Start Date: 1st October 2010

 

fax: +(44) 1786 467843
email: m.j.sjolund@stir.ac.uk

PhD Thesis Title

Interactions between natural and anthropogenic impacts on the genetic diversity and population structure of European beech forests

Funded by the Natural Environment Research Council (NERC) through the BiodivERsA ERA-Net project

Overview

My research explores the genetic implications of natural processes and human impact on plant populations. With particular focus on beech forests, I examine how levels of genetic diversity, gene flow, and spatial genetic structuring are influenced at the stand-scale by historic management practices, and at the regional scale by human-mediated species translocations, post-glacial colonisation, and population isolation. I am particularly interested in reconciling genetic evidence with paleoecological data and historical records that may provide further insight into population history.

My research has implications for forest management and the conservation of forests under predicted climate change, as a loss in genetic diversity and changes in genetic structure may compromise forest persistence in the future.

Study Species

The European beech tree, Fagus sylvatica, is one of the most important broadleaved tree species in Europe. It is a keystone species and represents a habitat known for its high floral and faunal biodiversity. It is the dominant tree species in most of Europe owing to its shade-tolerance and its ability to grow on several soil types. However, beech is especially sensitive to water logging and drought, and together with habitat loss, poses a risk for the persistence of beech forests under predicted climate change. Beech displayed a relatively slow rate of spread during the Holocene post-glacial colonisation, compared to other temperate tree species. Its resulting 14 million ha range has therefore experienced prolonged human impact throughout its migration, with contemporary forests harbouring high ecological, economic, and cultural value.

 Semi-natural beech forest - Spessart Mountain Range, Germany.  Ancient Beech Coppice - Montage de Lure, France.  Wood pasturage with Pollards - New Forest, United Kingdom.
Examples of different forms of beech forest in our study sites. LEFT: Semi-natural beech forest - Spessart Mountain Range, Germany. MIDDLE: Ancient Beech Coppice - Montage de Lure, France. RIGHT: Wood pasturage with Pollards - New Forest, United Kingdom. [Photographs by M. J. Sjölund]

Research Projects

The benefits and hazards of exploiting vegetative regeneration for forest conservation management in a warming world.

We reviewed the state of knowledge concerning the impacts of traditional forest management practices which exploited vegetative regeneration, such as coppicing and pollarding. The review highlights how these practices and their cessation affects forests at the molecular to the ecosystem level. We considered the potential of using the coppice selection system as a tool to improve forest resilience under climate change.

Coppice management of forests impacts spatial genetic structure but not genetic diversity in European beech (Fagus sylvatica L.).

We determined the effects of forest management on genetic diversity and fine-scale spatial genetic structure through pairwise comparative studies of coppiced vs. natural regenerated forest stands in in Germany, France, and Italy. Coppicing alters the primary regeneration pathway within a stand, and therefore is expected to alter the level and structuring of genetic diversity within populations.

Estimates of genetic diversity were found to be equally high in coppices as those found in natural forests. There was a small, but significant, increase in the extent of spatial genetic structure in coppice stands, indicating that local-scale patterns of gene flow had been altered by generations of forest management.

Cryptic genetic structure persists in Britain’s native Fagus sylvatica L. Kuhn forest despite a prolonged history of human translocations 

Palynological evidence suggests that beech arrived in Britain at 3000 BP, relatively later than other temperate tree species. Because of its late arrival, its native range is often presumed to be limited to the south-east of Britain. Beech has been historically, widely planted outside of its putative native range and presently occurs throughout Great Britain.

We were still able to detect cryptic phylogeographic signals of post-glacial colonisation when using historical and palynological evidence to identify potential stand origins of study sites. However, Bayesian individual assignment methods indicated that gene flow throughout the range has created a regional gradient of genetic variation, which obscures the boundary between the putative native and non-native range.

Gene flow at the leading range edge - the long-term consequences of isolation in European Beech (Fagus sylvatica L. Kuhn)   

We examined the leading edge of beech in Southern Sweden to identify the effects of isolation on the amount and distribution of genetic variation in populations. The range of beech in Sweden was extensively mapped in 1927-30 byLindquist (1931) using aerial reconnaissance techniques. This map was an extremely informative resource identifying stands of pure/beech-dominated forests, mixed stands with beech, and solitary trees. We geo-referenced the map to attain detailed area- and distance-based measurements of isolation for several sites exhibiting various degrees of isolation.

Isolation was found to lead to a reduction in genetic diversity within sites and an increase in the level of genetic differentiation between sites. Results obtained using Bayesian individual assignment methods, examined in the light of palynogical evidence, indicated a combination of isolation and post-glacial colonisation dynamics were responsible in shaping the population genetic structure of Swedish beech forests.

BEFOFU

My PhD forms part of a larger project called Beech Forests for the Future (BEFOFU) which is an interdisciplinary EU project that is run in conjunction with several European partners. BEFOFU aims to synthesise information on the ecological, economic, and policy aspects of beech forest protection, focusing on forests that form part of the Natura 2000 network.

Public Outreach

I am a STEM ambassador which is a recognised network of volunteers that are involved in several activities concerning STEM (Science, Technology, Engineering, and Maths) subjects at schools.

I organised a winter tree ID activity, together with Laura Cunningham from the Scottish Wildlife Trust, at the Glasgow Science Center as part of their Sustainable Science Schools Event. It was held on March 21 - the first ever International Day of Forests established by the United Nations. The event was featured on the UN FAO website as part of a slideshow of International Forest Day activities.

Other Research Interests

I collaborated with my Master’s Supervisor, Dr David Burslem, on his research into the mechanisms that underlie the coexistence of numerous conifer and angiosperm species in the warm temperate rain forests of northern New Zealand. This project explores whether partitioning along niche axes contributes to species coexistence, by identifying trade-offs measured in fitness costs. We examined whether a growth-survival trade-off differentiates angiosperms and conifers along axes of light and soil nutrient availability using the tree flora of Puketi Forest as a case study system. This work was implemented collaboratively with Dr Peter Bellingham of Landcare Research in Lincoln, New Zealand.

Publications

Sjölund, M.J., Jump, A.S., 2015. Coppice management of forests impacts spatial genetic structure but not genetic diversity in European beech (Fagus sylvatica L.). Forest Ecology and Management. 336, 65-71.

Sjölund, M.J. & Jump, A.S. (2013). The benefits and hazards of exploiting vegetative regeneration for forest conservation management in a warming world. Forestry: 10.1093/forestry/cpt030.

© University of Stirling FK9 4LA Scotland UK • Telephone +44 1786 473171 • Scottish Charity No SC011159
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