To predict the long-term effects of climate changeglobal warming and changes in precipitationon t... more To predict the long-term effects of climate changeglobal warming and changes in precipitationon the diameter (radial) growth of jack pine (Pinus banksiana Lamb.) and black spruce (Picea mariana [Mill.] B.S.P.) trees in boreal Ontario, we modified an existing diameter growth model to include climate variables. Diameter chronologies of 927 jack pine and 1173 black spruce trees, growing in the area from 47°N to 50°N and 80°W to 92°W, were used to develop diameter growth models in a nonlinear mixed-effects approach. Our results showed that the variables longterm average of mean growing season temperature, precipitation during wettest quarter, and total precipitation during growing season were significant (alpha = 0.05) in explaining variation in diameter growth of the sample trees. Model results indicated that higher temperatures during the growing season would increase the diameter growth of jack pine trees, but decrease that of black spruce trees. More precipitation during the wettest quarter would favor the diameter growth of both species. On the other hand, a wetter growing season, which may decrease radiation inputs, increase nutrient leaching, and reduce the decomposition rate, would reduce the diameter growth of both species. Moreover, our results indicated that future (2041-2070) diameter growth rate may differ from current growth rates for both species, with conditions being more favorable for jack pine than black spruce trees. Expected future changes in the growth rate of boreal trees need to be considered in forest management decisions. We recommend that knowledge of climate-growth relationships, as represented by models, be combined with learning from adaptive management to reduce the risks and uncertainties associated with forest management decisions.
Individual-tree distance independent diameter growth models were developed for black spruce and j... more Individual-tree distance independent diameter growth models were developed for black spruce and jack pine plantations. Data used in this study came via stem analysis on 1170 black spruce (Picea mariana [Mill.] B.S.P.) and 800 jack pine (Pinus banksiana Lamb.) trees sampled from 75 stands of 25 even-aged monospecific plantations for each species in the Canadian boreal forest region of northern Ontario. Of the 75 stands, 50 were randomly selected for each species and all trees from these stands were used for model development. Trees from the remaining stands were used for model evaluation.
& Introduction The wavelet-based functional approach was evaluated for modelling tree taper of ja... more & Introduction The wavelet-based functional approach was evaluated for modelling tree taper of jack pine (Pinus banksiana Lamb.) trees grown in the Canadian boreal forest region. & Objectives Wavelet-based functional fixed and mixedeffects models were developed to predict tree taper, and these models were evaluated for their predictive accuracy using calibration and evaluation data sets. & Results and discussion Diameters predicted using both fixed and mixed-effects taper models were unbiased for calibration data set as the 95% credible limits included 0 at all locations along the boles. The diameters predicted by these models for validation data set, however, were unbiased only at four out of 11 locations as the 95% credible limits of mean bias using fixed effects model did not include 0 at other locations. & Conclusion The study concludes that the wavelet-based taper models are able to describe the taper of the trees used in fitting the model but are unable to capture the mean taper function of the trees not used in fitting the model.
To predict the long-term effects of climate changeglobal warming and changes in precipitationon t... more To predict the long-term effects of climate changeglobal warming and changes in precipitationon the diameter (radial) growth of jack pine (Pinus banksiana Lamb.) and black spruce (Picea mariana [Mill.] B.S.P.) trees in boreal Ontario, we modified an existing diameter growth model to include climate variables. Diameter chronologies of 927 jack pine and 1173 black spruce trees, growing in the area from 47°N to 50°N and 80°W to 92°W, were used to develop diameter growth models in a nonlinear mixed-effects approach. Our results showed that the variables longterm average of mean growing season temperature, precipitation during wettest quarter, and total precipitation during growing season were significant (alpha = 0.05) in explaining variation in diameter growth of the sample trees. Model results indicated that higher temperatures during the growing season would increase the diameter growth of jack pine trees, but decrease that of black spruce trees. More precipitation during the wettest quarter would favor the diameter growth of both species. On the other hand, a wetter growing season, which may decrease radiation inputs, increase nutrient leaching, and reduce the decomposition rate, would reduce the diameter growth of both species. Moreover, our results indicated that future (2041-2070) diameter growth rate may differ from current growth rates for both species, with conditions being more favorable for jack pine than black spruce trees. Expected future changes in the growth rate of boreal trees need to be considered in forest management decisions. We recommend that knowledge of climate-growth relationships, as represented by models, be combined with learning from adaptive management to reduce the risks and uncertainties associated with forest management decisions.
Individual-tree distance independent diameter growth models were developed for black spruce and j... more Individual-tree distance independent diameter growth models were developed for black spruce and jack pine plantations. Data used in this study came via stem analysis on 1170 black spruce (Picea mariana [Mill.] B.S.P.) and 800 jack pine (Pinus banksiana Lamb.) trees sampled from 75 stands of 25 even-aged monospecific plantations for each species in the Canadian boreal forest region of northern Ontario. Of the 75 stands, 50 were randomly selected for each species and all trees from these stands were used for model development. Trees from the remaining stands were used for model evaluation.
& Introduction The wavelet-based functional approach was evaluated for modelling tree taper of ja... more & Introduction The wavelet-based functional approach was evaluated for modelling tree taper of jack pine (Pinus banksiana Lamb.) trees grown in the Canadian boreal forest region. & Objectives Wavelet-based functional fixed and mixedeffects models were developed to predict tree taper, and these models were evaluated for their predictive accuracy using calibration and evaluation data sets. & Results and discussion Diameters predicted using both fixed and mixed-effects taper models were unbiased for calibration data set as the 95% credible limits included 0 at all locations along the boles. The diameters predicted by these models for validation data set, however, were unbiased only at four out of 11 locations as the 95% credible limits of mean bias using fixed effects model did not include 0 at other locations. & Conclusion The study concludes that the wavelet-based taper models are able to describe the taper of the trees used in fitting the model but are unable to capture the mean taper function of the trees not used in fitting the model.
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