Urban Hjorth

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The relationships between the spatial locations and attributes of trees and the abundance of individual ground vegetation species, were studied on a large database from the 1985-86 National Forest Inventory of Finland. The influence potential, derived from ecological field theory, was used as an index to quantify the effect of a tree species, and the(More)
Local-scale and large-scale factors can affect the presence of a species of understory vegetation in the forest. Local-scale factors may be the influence of surrounding trees, while climate and latitude are typically considered large-scale factors. A model for the presence of a species needs to take into account both scales. A conditional logistic model is(More)
The estimation of optimal preventive maintenance (PM) times is considered. When failure and PM cause the only costs of interest, and the steady state cost-rate is to be minimized, very small samples of times to failure can often be effectively used. In particular, with only 10 failures the mean extra cost, due to statistical uncertainty, is in many(More)
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