Steen Magnussen

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A central problem in the analysis of genetic field trials is the dichotomy of “genetic” and “environmental” effects because one cannot be defined without the other. Results from 768,000 simulated family trials in complete randomized block designs demonstrated a serious upward bias in estimates of family variance components from multi-unit plot designs when(More)
In advanced generation seed orchards, tradeoffs exist between genetic gain obtained by selecting the best related individuals for seed orchard populations, and potential losses due to subsequent inbreeding between these individuals. Although inbreeding depression for growth rate is strong in most forest tree species at the individual tree level, the effect(More)
Forest inventory data often provide the required base data to enable the largearea mapping of biomass over a range of scales. However, spatially explicit estimates ofabove-ground biomass (AGB) over large areas may be limited by the spatial extent of theforest inventory relative to the area of interest (i.e., inventories not spatially exhaustive), orby the(More)
Canopy height data collected with an airborne laser scanner (ALS) flown across unmanaged parts of Canada’s boreal forest in the summer of 2010 were used—as stand-alone data—to derive a least-squares polynomial (LSPOL) between presumed post-fire recovered canopy heights and duration (in years) since fire (YSF). Flight lines of the >25,000-km ALS survey(More)
A new species richness estimator applicable to probability sampling with fixed-area (a) plots in a finite-area (A) population is presented and tested in simulated sampling from three stem-mapped forest compartments, and from six large collections of forest inventory data. The estimator of richness is the average number of species per plot times the sum—over(More)
National estimates of deforestation rates may be based on a survey. Precise estimation requires an efficient design. When deforestation rates are low (<1%) large sample sizes are required with traditional sampling designs to meet a precision target. This study explores the efficiency of adaptive cluster sampling (ACS) for this estimation problem. The(More)
In applications of the k-nearest neighbour technique (kNN) with real-valued attributes of interest (Y) the predictions are biased for units with ancillary values of X with poor or no representation in a sample of n units. In this article a modelassisted calibration is proposed that reduces unit-level extrapolation bias. The bias is estimated as the(More)
This paper focuses on the use of models for increasing the precision of estimators in large-area forest surveys. It is motivated by the increasing availability of remotely sensed data, which facilitates the development of models predicting the variables of interest in forest surveys. We present, review and compare three different estimation frameworks where(More)
Selection indices that maximize the correlation between an individual organism's index score and its breeding value frequently require a priori known “economic” weights before the optimum phenotypic weights can be estimated. The long generation intervals and economic uncertainty that surround forest tree breeding can make the choice of weights arbitrary. In(More)