Union Catalogue of Agricultural Libraries in the Netherlands
The WUR Library Catalogue contains bibliographic data on books and periodicals held by the libraries of Wageningen University and Research Centre and some 15 associated libraries. Holding data are added to each record.
Subjects covered include Agrotechnology, Food and Food Production, Plant and Animal Sciences, Soil Science, Geo-information, Landscape and Spatial Planning, Water and Climate, Ecosystem Studies, Economics and Society.
The joint collections of the participating libraries cover a substantial part of the internationally available scientific literature in these disciplines.
As far as Dutch scientific literature in these fields is concerned, coverage can be considered near 100%, including much of the so-called "grey literature".
All titles are entered in their original language. Keywords are added to facilitate subject searching.
The database is updated every day and now contains over 830.000 records.
Thinning trees by form and defects (tree-class thinnings) and practical or free thinning (according to the surrounding trees) were unsuitable for comparing thinning methods by the subjectivity of the involved tree classification methods.A thinning criterion based on 'top height' and 'stem number' proved objective. By assuming different ratios between crown diameter and height at a certain developmental stage of the trees, reduction in stem number could be obtained, related to the mean 'top height', which was height, measured and averaged on the 100 highest trees, uniformly distributed over 1 ha. Assuming different ratios gave different stem number reductions. Thus the results of different objective thinning grades could be compared.Initial stem number was determined by the ratio crown diameter: height and by the relation between spacing and amount of thinning. In spacing experiments the influence of spacing on stem form and the tree defects already yielded conclusions about stem number (not too low; higher on worse soil), mixed plantations and the way of planting (planting in rows was recommended). Conclusions on amount of thinning were not yet possible. The method was simple in practice, even for other tree species.
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