Annu Kaila

Impact of Re-wetting of Forestry-Drained Peatlands on Water Quality—a Laboratory Approach Assessing the Release of P, N, Fe, and Dissolved Organic Carbon

A laboratory column study with peats from four sites from south-central Finland and two sites from blanket peats in the west of Ireland was established to assess the factors contributing to P, N, Fe, and dissolved organic carbon (DOC) transfer to receiving water courses from restored forestry-drained peatlands. The study indicated that the DOC and Fe release from re-wetted peats are likely governed by the amount of Fe in peat and the degree of Fe reduction upon re-wetting. In contrast to our other hypothesis concerning DOC, high degradability of organic matter was not related to high DOC release. Nitrate release was found to largely cease along with oxygen depletion, but ammonium release was considerable from a site with high nitrification potential before wetting. The release of P from anoxic peat was complicated in the sense that it appeared to be controlled by many factors simultaneously. In the nutrient-poor sites, the P release increased following re-wetting, probably because of their high easily soluble peat P content and low Al and Fe content, resulting in high anoxic P mobilization, but limited re-sorption of the mobilized P. Among the three nutrient-rich sites, there was either no P release upon re-wetting or higher P release than from the nutrient-poor sites. Low risk for P release following re-wetting in nutrient-rich sites was associated with low content in peat of easily soluble P and a high molar Fe/P ratio.

Natural and Restored Wetland Buffers in Reducing Sediment and Nutrient Export from Forested Catchments: Finnish Experiences

One of the water quality management practices in forested catchments is to construct wetland buffers between managed areas and recipient water courses. Wetland buffers can be constructed simply by routing runoff from forested areas to natural peatlands and wetlands, or by rewetting lower sections of drained peatlands by filling in or blocking the drainage ditches. The use of natural and restored wetland buffers for reducing nutrient and sediment export from forested catchments, particularly catchments dominated by forestry-drained peatlands, has been studied actively in Finland during the last 15 years. The studies have shown highly variable retention capacity for wetland buffers with different site characteristics and under different environmental conditions. In favorable conditions, high amounts of sediments and adhered mineral elements may be deposited within peat and surface vegetation of the buffer. Dissolved nutrients can be retained biologically into plant and microbial biomasses and chemically into peat. In contrast, nitrogen can also be lost into the atmosphere in gaseous form. In this literature review, we summarize the results of the experiments established on natural and restored wetland buffers in forested catchments in Finland to clarify the different processes and factors controlling their nutrient and sediment retention capacity. We also discuss the limitations and possible negative consequences of using wetland buffers for managing water quality in forested catchments.

Vegetation relations in the border regions of NE Finland and Russian Karelia: a review of Wainio (1878)

Abstract E. A. Vainio (Wainio) defended his doctoral thesis, “Vegetation relations in the border regions of NE Finland and Russian Karelia” in 1878 at the age of 24. This was the first biological dissertation published in Finnish. In his work Vainio presented relations between plant species in his study area, and identified factors that increased or decreased the dominance of different kinds of vegetation and distributional limits for different species. Vainio expressed the early idea of site-type classification based on vegetation patterns: “Plant species tend to grow in certain clusters which occupy bigger or smaller surfaces, which offer them similar kinds of physical–chemical conditions”. He defined the concept of plant topography, clarified which plant species clusters were present in his study area, what chemical–physical conditions defined them and the reasons for their existence. A. K. Cajander developed these ideas further in his classical forest and mire site-type classifications in the early twentieth century. Although Vainios work was ahead of his time since he not only described plant communities but also tried to explain their existence with a site-ecological approach, his Finnish colleagues did not cite Vainios study during his lifetime, mainly for political reasons. His life demonstrates that a persons influence may be hidden because of personal and/or political causes.