Current issue: 53(4)
Silver birch (Betula pendula Roth.) is one of the main pioneer tree species occupying large areas of abandoned agricultural lands under natural succession in Estonia. We estimated aboveground biomass (AGB) dynamics during 17 growing seasons, and analysed soil nitrogen (N) and carbon (C) dynamics for 10 year period in a silver birch stand growing on former arable land. Main N fluxes were estimated and nitrogen budget for 10-year-old stand was compiled. The leafless AGB and stem mass of the stand at the age of 17-years were 94 and 76 Mg ha–1 respectively. The current annual increment (CAI) of stemwood fluctuated, peaking at 10 Mg ha–1 yr–1 at the age of 15 years; the mean annual increment (MAI) fluctuated at around 4–5 Mg ha–1. The annual leaf mass of the stand stabilised at around 3 Mg ha–1 yr–1. The stand density decreased from 11600 to 2700 trees ha–1 in the 8- and 17-year-old stand, respectively. The largest fluxes in N budget were net nitrogen mineralization and gaseous N2-N emission. The estimated fluxes of N2O and N2 were 0.12 and 83 kg ha–1 yr–1, respectively; N leaching was negligible. Nitrogen retranslocation from senescing leaves was approximately 45 kg ha–1, N was mainly retranslocated into stembark. The N content in the upper 0–10 cm soil layer increased significantly (145 kg ha–1) from 2004 to 2014; soil C content remained stable. Both the woody biomass dynamics and the N cycling of the stand witness the potential for bioenergetics of such ecosystems.
The size of the field and the ditching on it as well as the condition of the field at the time of the surrender of Porkkala area (from Finland to Russia) play an important role on how far the natural regeneration of the fields has progressed.
Larger open fields have naturally regenerated only on sides where the surrounding forest can spread the seeds or the thicket of saplings has reached, whereas small parcels of fields have normally been fully forested. Most important species have been e.g. silver birch and pubescent birch, grey and common alders and European aspen as well as pine and spruce. The broad leaved species are dominant.
The PDF contains a summary in Finnish.
The timber companies began acquiring forest land in 1890s which raised concerns about decrease of the number of private farms and agricultural land, as had happened in Sweden earlier. This was not considered to be a major problem in Finland, but the sale of homesteads on former state lands for sawmill companies was considered to be against their objective. One reason for the sale of farms was the farmers’ poor conception of the value of the land. In 1915 three decrees that restricted the right of companies that use timber to buy land were approved. The article discusses in detail the arguments that led to the legislation and compares it to the situation in Sweden.
A survey was commissioned to study the of landholdings of the companies, and to compare it with farming in private and company owned farms. The article includes a study about individual farms in the municipalities of Multia, Heinävesi, Sulkava, Ruokolahti and Luumäki, and about land use in the areas.
The PDF includes a summary in German.
Under the soil bank act, which took effect in 1969, 85,000 hectares of agricultural land were withdrawn from agricultural production in order to cut down the heavy surpluses of grain and butter in Finland. The farmers have a possibility to afforest their soil bank land partly on public funds, and if they choose to do so they receive a compensation of 250 Fmk for 15 years, instead of the nine years which is the maximum duration of a soil bank contract.
The study involved interviewing of 136 farmers sampled from the total of 13,368. The farmers were planning to afforest a total of 18,600 ha by the end of 1972. The main species were birch (Betula sp.) 40%, Norway spruce (Picea abies (L.) H. Karst.) and Scots pine (Pinus sylvestris L.) both 30%. The main reasons (mentioned by 65% of the farmers) for afforestating the soil bank land were the unfavourable conditions for agriculture. On the other hand, 43% of those who had decided not to afforest felt that their land is too good to be planted with trees. One fifth of those not afforesting said that they themselves would not benefit from the afforestation and therefore were not interested in investing in forestry. The attitudes of the farmers seem to have also influenced their decision on afforestation. Those who had taken a positive decision on afforestation appeared to take more positive attitude in regard to forestry than other farmers.
The soil bank act does not seem to solve permanently Finland’s problem of the surpluses of agricultural products since the soil bank farmers planned to revert two thirds of the soil bank land under cultivation on the expiration of the soil bank act.
The PDF includes a summary in English.