Population structure and distribution of the declining endangared forest plant Chimaphila umbellata
Independent thesis Advanced level (degree of Master (Two Years)), 40 credits / 60 HE creditsStudent thesis
The occurrence of the rare forest plant Chimaphila umbellata has decreased with approximately 80 % in Uppland and its decline is also reported for other regions in Sweden. Suggested causes of decline include the increasingly shaded conditions in understory habitats and increased competition from Vaccinium myrtillus and graminoid species. The aim of the study was to investigate the effects of various biotic and abiotic conditions on C. umbellata populations with regard to population size, flowering frequency, fruit set and seed production. Conditions analyzed include light inflow, coverage of competitive species, soil nitrogen, continuity of forest cover and soil texture, which were investigated in 38 C. umbellata sites in Uppland and Södermanland, Sweden. Results showed that population size was negatively affected by the coverage of competitive species. Population size was not affected by light availability, but increased shading resulted in a decreased flowering frequency. Fruit set decreased with increasing coverage of competitive species and seed production per capsule decreased with increasing soil nitrogen content. This study shows that the overall changes in present-day forest conditions have negative effects on C. umbellata. Longevity and clonal recruitment may act as buffers of these unfavourable environmental conditions, which might contribute to an extinction debt in the species. There is a need for urgent and targeted management in forest habitats, including moderate disturbance regimes to reduce competition and increase light inflow, to maintain viable populations of Chimaphila umbellata in our forests.
Place, publisher, year, edition, pages
2014. , 30 p.
Biodiversity, conservation, forest management, forest structure, ground vegetation, light availability, plant population dynamics
IdentifiersURN: urn:nbn:se:su:diva-103039OAI: oai:DiVA.org:su-103039DiVA: diva2:714768
Eriksson, Ove, Professor
Ehrlén, Johan, Professor