Articles containing the keyword 'paludification'

The relation between the occurrence of forest site types and swamp types was studied using data collected in the national line survey of Finnish forests carried out in 1921‒1924. The majority of peatlands in Finland has been formed by forest land becoming paludificated. When the peat layer is thin, the fertility of the peatland depends on the underlying mineral soil, consequently, good swamp types occur on fertile subsoil and poor types on poor subsoil. When the peat layer becomes thicker, the relationship weakens. The surrounding mineral soils influence the quality of the peatland by the runoff from the catchment area. The direct comparison of forest site and swamp types is not possible, because for one forest site type there are several swamp types that have different levels of humidity. According to the study, a very distinct mutual relation can be seen between occurrence of forest site types and swamp types.

The PDF includes a summary in English.

• Ilvessalo, E-mail: yi@mm.unknown

No agreement has yet been reached about formation of podzols, and their distribution in Finland has not been studied. It is, however, known that most of the forest soils are leached. The compacted ortstein is relatively rare in Southern Finland, but common in the gravely soils in Lapland. This study focuses on whether ortstein formations facilitate paludification. The study is based on observations in drained peatlands in Toivakka and Multia. Ortstein can rarely be found under the actual peatlands. It is often formed in mineral soil threshold areas, where it can be up to one meter thick. The ortstein formation was stronger in poorer soil types. Also, it is compacted into a harder layer in gravely soils than in sandy soil. These formations seem to be caused by humus-rich water flowing from the peatlands.

The soil is not leached, and ortstein is not formed in wet, low-lying peatlands, and has, therefore, no role in their paludification. In drier peatlands, especially in slopes, an A horizon can be found. However, ortstein seems not to have a marked effect on paludification. When ortstein is formed in mineral soil threshold areas, their formation seems to be caused by water flow from the peatland. It may make the threshold area more compact, and thus further facilitate paludification.

The PDF includes a summary in German.

• Lukkala, E-mail: ol@mm.unknown

The investigations that have studied peat layers in peatlands have shown that the peatlands in several countries have layers containing tree stumps of different tree species. The stump layers have been explained by local hydrological changes that have caused paludification, or changes in climate.

Peat layers were studied in drained peatlands in Finland, and ditches were used to study the peat profiles. A peatland in Multia in Central Finland was studied in more detail. Tree stump layer patterns that would support the climate change explanation was not found in the Finnish peatlands. The peat changes usually gradually more oligotrophic towards the surface. The stump layers seemed to be caused by local drier periods. According to the layers of Sphagnum-peat near the bottom of the peatlands and the pollen studies indicate that the peatlands have been formed at different times. In South-West Finland, the peat profiles had more apparent layer patterns than in Central Finland, but these were not considered to be caused by changes in climate.

The PDF includes a summary in German.

• Lukkala, E-mail: ol@mm.unknown

Mechanical site preparation (MSP) is used prior to planting to control competing vegetation and enhance soil conditions, particularly in areas prone to paludification. Tree planting density can be adapted to the management context and objectives, as it influences yield and wood quality. However, the combined effects of MSP and planting density on understory vegetation composition, functional traits, and diversity remain uncertain. We thus conducted a study in the Clay Belt region of northwestern Quebec, Canada. After careful logging, the study area was divided into nine sites, each receiving one of three treatments: plowing, disc trenching, or no preparation. Sites were further divided into two, with black spruce (Picea mariana [Mill.] Britton, Sterns & Poggenb.) seedlings planted at either a low planting density of 1100 seedlings ha^-1 or a high planting density of 2500 seedlings ha^-1. After nine years, we assessed understory composition, diversity, key functional traits, sapling density and growth of planted trees. Careful logging alone led to a higher density of naturally established conifers compared to plowing or disc trenching. The interaction between planting density and MSP significantly influenced understory diversity and composition in plowed plots. Understory composition was affected by the soil C/N ratio, coniferous species, and deciduous species density. The growth of black spruce was notably enhanced with higher planting density in the plow treatment only. Neither planting density nor MSP alone affected tree height and diameter. Our results suggest that combining plowing with high-density planting can enhance stand growth and improve forest productivity. These findings guide future research on paludified forests.

• Fetouab, Institute for Forest Research and Centre for Forest Research, Université du Québec en Abitibi-Témiscamingue, 445 boul. de l’Université, Rouyn-Noranda, QC J9X 5E4, Canada E-mail: amira.fetouab@uqat.ca
• Fenton, Institute for Forest Research and Centre for Forest Research, Université du Québec en Abitibi-Témiscamingue, 445 boul. de l’Université, Rouyn-Noranda, QC J9X 5E4, Canada https://orcid.org/0000-0002-3782-2361 E-mail: nicole.fenton@uqat.ca
• Thiffault, Institute for Forest Research and Centre for Forest Research, Université du Québec en Abitibi-Témiscamingue, 445 boul. de l’Université, Rouyn-Noranda, QC J9X 5E4, Canada; Canadian Wood Fibre Centre, Natural Resources Canada, 1055 du P.E.P.S, P.O. Box 10380, Sainte-Foy Stn, Québec, QC G1V 4C7, Canada https://orcid.org/0000-0003-2017-6890 E-mail: nelson.thiffault@canada.ca
• Barrette, Institute for Forest Research and Centre for Forest Research, Université du Québec en Abitibi-Témiscamingue, 445 boul. de l’Université, Rouyn-Noranda, QC J9X 5E4, Canada; Direction de la recherche forestière, Ministère des Ressources naturelles et des Forêts, 2700 rue Einstein, Québec, QC G1P 3W8, Canada https://orcid.org/0000-0001-5937-382X E-mail: martin.barrette@mffp.gouv.qc.ca

In the boreal forest of eastern Canada, a large proportion of black spruce (Picea mariana [Mill.] Britton, Sterns & Poggenb.) stands are affected by paludification. Edaphic conditions that are created by paludification processes, including an abundance of microsites with high moisture and low nutrient contents, hinder forest regeneration. Disturbance of paludified sites by mechanical soil preparation (MSP) reduces organic layer thickness, while generating a range of substrates for regeneration establishment. Yet, little information is available regarding the effects of these substrates on tree growth. Our objective was to determine the effect of organic, mineral and organo-mineral substrates that are created following MSP of a paludified site on the growth and root development of black spruce seedlings in a semi-controlled environment. We demonstrated that substrate exerted a significant effect on seedling growth and foliar concentrations of N, P and K. Increase in height and diameter were respectively greatest on clay (mineral) and mesic substrates. Substrate effects did not affect total biomass increases or final root biomass. Foliar nutrients (N, P, K) were relatively high in seedlings that were established on mesic substrates and relatively low for those established on clay substrates. To ensure successful seedling establishment, we recommend the application of MSP techniques that expose organic-mesic substrates on sites that are susceptible to paludification.

• Henneb, Institut de recherche sur les forêts (IRF), Université du Québec en Abitibi-Témiscamingue, 445 boul. de l’Université, Rouyn-Noranda, QC J9X 5E4, Canada http://orcid.org/0000-0003-4507-1219 E-mail: mohammed.henneb@uqat.ca
• Valeria, Institut de recherche sur les forêts (IRF), Université du Québec en Abitibi-Témiscamingue, 445 boul. de l’Université, Rouyn-Noranda, QC J9X 5E4, Canada http://orcid.org/0000-0002-9921-7474 E-mail: osvaldo.valeria@uqat.ca
• Thiffault, Institut de recherche sur les forêts (IRF), Université du Québec en Abitibi-Témiscamingue, 445 boul. de l’Université, Rouyn-Noranda, QC J9X 5E4, Canada; Natural Resources Canada, Canadian Wood Fibre Centre, 1055 rue du PEPS, P.O. Box 10380, Stn Sainte Foy, Quebec, QC G1V 4C7, Canada http://orcid.org/0000-0003-2017-6890 E-mail: nelson.thiffault@canada.ca
• Fenton, Institut de recherche sur les forêts (IRF), Université du Québec en Abitibi-Témiscamingue, 445 boul. de l’Université, Rouyn-Noranda, QC J9X 5E4, Canada http://orcid.org/0000-0002-3782-2361 E-mail: nicole.fenton@uqat.ca

• Lafleur, NSERC-UQAT-UQAM Industrial Chair in Sustainable Forest Management, Université du Québec en Abitibi-Témiscamingue, 445 boul. de l’Université, Rouyn-Noranda, QC J9X 5E4, Canada E-mail: benoit.lafleur@uqat.ca
• Fenton, NSERC-UQAT-UQAM Industrial Chair in Sustainable Forest Management, Université du Québec en Abitibi-Témiscamingue, 445 boul. de l’Université, Rouyn-Noranda, QC J9X 5E4, Canada E-mail: njf@nn.ca
• Paré, Natural Resources Canada, Canadian Forest Service, Laurentian Forestry Centre, 1055 du P.E.P.S., P.O. Box 10380, Stn. Sainte-Foy, QC G1V 4C7, Canada E-mail: dp@nn.ca
• Simard, Département de Géographie, Université Laval, Pavillon Abitibi-Price, 2405 rue de la Terrasse, Québec, QC G1V 0A6, Canada E-mail: ms@nn.ca
• Bergeron, NSERC-UQAT-UQAM Industrial Chair in Sustainable Forest Management, Université du Québec en Abitibi-Témiscamingue, 445 boul. de l’Université, Rouyn-Noranda, QC J9X 5E4, Canada E-mail: yb@nn.ca