Current issue: 57(1)
Under compilation: 57(2)
Berry yield of rowan tree (Sorbus aucuparia L.) was studied by picking and weighing the berries in a tree, counting the number of clusters by the eye, estimating the number of clusters by samples of 0.5 m2, and by counting the dropped berries. In the last tree methods average weight of berries in a cluster was assessed by weighing a sample of clusters. The size of the tree and the abundance of the berries influenced the choice of method. The first two methods suited for small trees, the third for a tall tree with berries in abundance, and the fourth for those cases where birds had eaten a large portion of the berries.
The berry yields of 88 rowan trees were studied in Central Finland in 1983, a year of exceptionally high berry yield. The yield of berries averaged 23 kg per tree, the number of clusters 1,249 per tree and the number of berries 42,500 per tree.
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A survey was carried out among forest foremen and forest technicians to record their observations on the value of various swamp and forest types as producers of berries and on the effect of drainage of peatlands upon the berry yields. Comparative agreement existed on the best blueberry (Vaccinium myrtillus L.) forest types and on the best lingonberry (Vaccinium vitis-idaea L.) forest types of rather dry upland sites. Fuscum pine swamps or fuscum bogs were considered best for the most part as regards the yield of cloudberry (Rubus chamaemorus L.). The replies showed rather great dispersion.
Agreement existed as well on the relation between drainage of peatlands and the yields of our economically most important swamp berries, cloudberry and cranberry. 90% of those responding were of the opinion that drainage reduces the cloudberry yield in the long term and a full 97% indicated that cranberry crop diminishes as well.
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A study on the lingonberry (Vaccinium vitis-idaea L.) was made in 1976. The berry yield was studied by picking along 17 lines, each 1,000 m long. The picking and use of lingonberry were studied by an inquiry addressed to the families engaged in such an occupation. The marketing of the lingonberry was investigated by interviewing purchasers, and by means of reports based on purchasing certificates of the purchacers. The total yield of lingonberry in Pihtipudas was 1.2 million kg or 18 kg per hectare of productive forest. Only 7% of the total yield of the berry was picked. 47% of the lingonberries picked were used by the families themselves, 48% were sold and 5% were used for other purposes. The families who sold lingonberries earned, on an average, 350 Fmk.
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The coverage of bilberry (Vaccinium myrtillus L.) was modelled as a function of site and stand characteristics using the permanent sample plots of the National Forest Inventory (NFI) (Model 1). The sample sites consisted of mineral soil forests as well as fells and peatland sites. Annual variation in the bilberry yield (Model 2) was analysed based on measurements over 2001–2014 in the permanent sample plots (so-called MASI plots) in various areas of Finland. We derived annual bilberry yield indices from the year effects of Model 2 and investigated whether these indices could be used to estimate annual variation in bilberry crops in Finland. The highest bilberry coverage was found in mesic heath forests and fell forests. On peatlands the coverage was, on average, lower than on mineral soil sites; the peatland sites with most bilberry coverage were meso-oligotrophic and oligotrophic spruce mires and oligotrophic pine mires. Our bilberry yield indices showed similar variation to those derived from the mean annual berry yields reported and calculated earlier using the MASI plots; the correlation between the indices was 0.795. This approach to calculating annual berry yield indices is a promising way for estimating total annual bilberry yields over a given period of time. Models 1 and 2 can be used in conjunction with the Miina et al.’s (2009) bilberry yield model when bilberry coverage, average annual yield and annual variation in the yield are to be predicted in forest planning.