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The Effect of Nitrogen Fertilization, Rock Type, and Habitat Type on Individual Tree Mortality Item Info

An individual tree mortality model for nitrogen fertilized Douglas-fir (Pseudotsuga menziesii var. glauca [Beissn.] Franco) stands was developed using data from permanent research plots located throughout the inland Northwest. The proposed linear logistic model included the following independent variables: a dummy variable for the two habitat types, a set of dummy variables for the five rock types, a set of dummy variables for the three N fertilizer treatments, diameter at breast height, crown ratio, and crown competition factor. The results show that N fertilization, rock type, and habitat type significantly affect individual tree mortality. The probabilities of tree mortality on fertilized plots were greater than those on control plots and increased with increasing N fertilizer application rates. Trees growing on granitic and metasedimentary rocks had lower foliar potassium concentration and exhibited greater probabilities of mortality than did those growing on other rocks. The probabilities of mortality for trees growing on sedimentary rocks were very low. Moist sites had lower soil fertility and produced higher mortality rates than dry sites. Furthermore, the N fertilization response ratio, defined as the annual mortality probability of a fertilized tree over the annual mortality probability of a unfertilized tree with identical tree and stand characteristics, was estimated based on the mortality model. The response ratios were nearly constant (about 1.4) across a range of tree diameters for all rock types with the 224 kg N treatment. The response ratios were also nearly constant (about 2.1) across a range of tree diameters for all rock types with the 448 kg N treatment. Finally, the mortality prediction model passed a validation test on independent data not used in model development.

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Title:
The Effect of Nitrogen Fertilization, Rock Type, and Habitat Type on Individual Tree Mortality
Creator:
Shen, G.; Hatch, C.R.; Moore, J.A.
Date Created (ISO Standard):
2000-07-28
Description:
An individual tree mortality model for nitrogen fertilized Douglas-fir (Pseudotsuga menziesii var. glauca [Beissn.] Franco) stands was developed using data from permanent research plots located throughout the inland Northwest. The proposed linear logistic model included the following independent variables: a dummy variable for the two habitat types, a set of dummy variables for the five rock types, a set of dummy variables for the three N fertilizer treatments, diameter at breast height, crown ratio, and crown competition factor. The results show that N fertilization, rock type, and habitat type significantly affect individual tree mortality. The probabilities of tree mortality on fertilized plots were greater than those on control plots and increased with increasing N fertilizer application rates. Trees growing on granitic and metasedimentary rocks had lower foliar potassium concentration and exhibited greater probabilities of mortality than did those growing on other rocks. The probabilities of mortality for trees growing on sedimentary rocks were very low. Moist sites had lower soil fertility and produced higher mortality rates than dry sites. Furthermore, the N fertilization response ratio, defined as the annual mortality probability of a fertilized tree over the annual mortality probability of a unfertilized tree with identical tree and stand characteristics, was estimated based on the mortality model. The response ratios were nearly constant (about 1.4) across a range of tree diameters for all rock types with the 224 kg N treatment. The response ratios were also nearly constant (about 2.1) across a range of tree diameters for all rock types with the 448 kg N treatment. Finally, the mortality prediction model passed a validation test on independent data not used in model development.
Subjects:
research (document genres) data modeling fertilizer statistics
Location:
North and Central Idaho; Eastern Washington; Western Montana; Northeastern Oregon
Publisher:
Forest Science
Source:
Shen, G., J.A. Moore, and C.R. Hatch. 2001. The effect of nitrogen fertilization and rock type on individual tree mortality. For. Sci .47:203-213.
Source Identifier:
The_Effect_of_Nitrogen_Fertilization_Rock_and_Habitat_Type_on_Individual_Tree_Mortality_FS_047_002_2000
Type:
text
Format:
application/pdf

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"The Effect of Nitrogen Fertilization, Rock Type, and Habitat Type on Individual Tree Mortality", Idaho Forestry Research Collection, University of Idaho Library Digital Collections, https://www.lib.uidaho.edu/digital/forestryresearch/items/forestryresearch923.html
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