Search results for "Taiga"
showing 10 items of 103 documents
Effects of hard frost and freeze-thaw cycles on decomposer communities and N mineralisation in boreal forest soil
2003
Abstract Decomposition and mineralisation rates generally increase with increasing moisture and temperature. The expected global climate change may enhance precipitation and raise the temperatures at boreal latitudes, but absence of snow together with occasional low temperatures may cause disturbances in soil processes and faunal communities. To test the effects of disturbances such as hard frosts and freeze-thaw cycles on decomposer populations and N mineralisation, we performed two experiments. In the field experiment, carried out in a pine forest, we induced low soil temperatures by preventing snow covering the ground. In the laboratory test we established three “winter” temperature regi…
Size matters in studies of dead wood and wood-inhabiting fungi
2011
Abstract Because biased biodiversity surveys may result in ineffective use of conservation or research resources it is important that measures for biodiversity are accurate. In forest ecosystems wood-inhabiting fungi are an ecologically important species group. We addressed the question whether or not the traditional methodology to survey only coarse woody debris provides accurate estimates of the assemblages of wood-inhabiting fungi or the dead wood itself. In this study, we included all dead wood pieces irrespective of the diameter. Our results showed that the chosen minimum size of studied dead wood pieces has crucial importance for species recordings of wood-inhabiting fungi and for rec…
Impacts of elevated CO2 and temperature on the soil fauna of boreal forests
2005
Abstract Responses of dominant soil decomposer animals in northern coniferous forests, enchytraeids and microarthropods, to elevated CO 2 concentration and temperature were studied by sampling an experiment consisting of closed field chambers with a ground area of 5.9 m 2 . Six species of enchytraieds were found in the study, with Cognettia sphagnetorum comprising 87% of all individuals. The treatments did not significantly affect the numbers of C. sphagnetorum . No treatment induced changes were found in oribatid mites, but numbers of acaridid mites were lowest in the chambers with elevated CO 2 concentration and in those with elevated temperature. The chambers had lower densities of actin…
Individual and Environmental Determinants of Daily Black Grouse Nest Survival Rates at Variable Predator Densities
2010
Nest predation in ground nesting black grouse (Tetrao tetrix) inhabiting managed boreal forests is arguably the single most important cause of nesting failure. Little is known, however, about indirect effects of other factors, such as maternal or environmental properties, and to what extent maternal and habitat qualities interact with varying levels of predator densities. Using an information-theoretical approach, we studied maternal and environmental determinants of daily nest survival rates under variable predator densities of 210 individual black grouse hens in central Finland. Environmental determinants were far more important than maternal ones, and the effects were more apparent at hi…
Emulating natural disturbances in boreal Norway spruce forests: Effects on ground beetles (Coleoptera, Carabidae)
2014
The disturbance regime of boreal forests has been substantially altered by human influence in northern Europe. In this context, emulations of natural disturbance have become increasingly common as management tools to minimize negative effects of forestry on biodiversity. In a large-scale habitat-restoration experiment conducted in Norway spruce stands in southern Finland, we tested the effects of controlled burning, partial harvesting, and increasing the amount of downed wood on ground beetles (carabids). We also evaluated the effects of moisture gradients within harvested sites. We collected beetles seven years after the treatments. The moisture gradient was the strongest determinant of ca…
Conservation of forest biodiversity using temporal conservation contracts
2012
Abstract Temporal conservation contracts are used to protect biodiversity in privately owned lands worldwide. We examine how stand characteristics and habitat requirements of target species affect the contract length in a boreal forest context. We develop an integrated optimization model and apply the model with data on endangered species occurring in spruce forests in Finland. The results suggest that a cost-effective conservation policy for protecting privately owned forest land involves both short- and long-term contracts between landowners and environmental agencies. The higher the conservation objective, the more intensively long-term contracts should be assigned. Managed stands should…
14. Abrupt cooling events at the very end of the last interglacial
2007
Abstract A comparison of a last interglacial annually laminated and varve counted maar lake record from the Eifel/Germany, with a laminated lake sediment record from Northern Germany, shows that high-resolution cores can be correlated across central Europe by dust/loess content, if the resolution of grain-size data is on the order of decades/centuries. Phases of widespread dust dispersal are the same as the cold events in the Greenland ice and North Atlantic sea-surface temperature patterns. The first occurrence of dust in Northern Germany and in the Eifel is during the late Eemian aridity pulse (LEAP, Sirocko et al., 2005) which is called C26 in ocean records (McManus, this volume). This c…
Mixotrophy in Pyroleae (Ericaceae) from Estonian boreal forests does not vary with light or tissue age
2017
SPE IPM UB; International audience; In temperate forests, some green plants, namely pyroloids (Pyroleae, Ericaceae) and some orchids, independently evolved a mode of nutrition mixing photosynthates and carbon gained from their mycorrhizal fungi (mixotrophy). Fungal carbon is more enriched in 13C than photosynthates, allowing estimation of the proportion of carbon acquired heterotrophically from fungi in plant biomass. Based on 13C enrichment, mixotrophic orchids have previously been shown to increase shoot autotrophy level over the growth season and with environmental light availability. But little is known about the plasticity of use of photosynthetic versus fungal carbon in pyroloids. Met…
Effects of stump removal on soil decomposer communities in undisturbed patches of the forest floor
2011
Abstract Soil preparation after clear-cutting leads to fragmentation of forest floor and, consequently, changes the habitat of decomposers. Stump removal for bioenergy is further increasing the disturbance in the soil. We studied responses of decomposers to stump removal in boreal spruce forests during the first 4 years after clear felling in relation to mounding. Samples for each decomposer organism group were taken from undisturbed forest floor patches that are the main habitat for decomposers after forest regeneration and whose amount and size obviously differ between the treatments. Microbial biomasses and community structure, and the abundance of enchytraeids, were not found to be affe…
Dead-wood effects on enchytraeids and nematodes in thinned and unmanaged Norway spruce forests
2009
Abstract The effects of dead wood on enchytraeids and nematodes were studied in thinned and uncut Norway spruce forests in two experiments. Fifteen pairs of small spruce logs (one enclosed in polyethylene sheet and another untreated control) were returned to the forest floor in a complete randomized block design after thinning. Soil under the logs and at distances of 0–6 cm and 6–12 cm from each log was sampled after one growing season, and enchytraeids and nematodes were extracted and forest floor properties measured. Log enclosure increased enchytraeid length irrespective of the distance from the log. Soil moisture or pH were not affected by enclosure, but organic matter content was reduc…