Thinning and Urea Fertilization Effects on Emerging Grand Fir (Abies Grandis) Foliage and Growth of Western Spruce Budworm (Choristoneura Occidentalis) Larvae
Thinning and Urea Fertilization Effects on Emerging Grand Fir (Abies Grandis) Foliage and Growth of Western Spruce Budworm (Choristoneura Occidentalis) Larvae

Author: Thomas J. Savage

Publisher:

Published: 1987

Total Pages: 82

ISBN-13:

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The objective of this study was to determine how the balance of carbon to nitrogen in a grand fir ecosystem affects the chemistry of emerging grand fir foliage and the growth of western spruce budworm larvae. Forest plots in the grand fir zone of eastern Oregon were thinned, thinned and fertilized, fertilized without thinning, or left as a control to determine how increased nitrogen availability alters the efficacy of carbon-based chemical defenses at different light levels. Thinning did not significantly alter any of the foliar chemical fractions measured while fertilization increased the concentration of foliar nitrogen and free amino acids. Thinning increased tree vigor (g wood produced per m2 foliage), but fertilization only increased vigor in the thinned plots. Fertilization increased the weights of western spruce budworm pupae; thinning had no effect. Male and female pupal weights correlated with foliar free amino acid concentration and the ratios of foliar free amino acids to foliar nitrogen, available carbohydrates, and lignin, but stepwise regression analysis showed that foliar free amino acid concentration alone explained most of the variation in pupal weights. The correlation of foliar free amino acid concentration with male and female pupal weights, and the lack of correlation of any indices of carbohydrate availability suggest that changes in available nitrogen rather than changes in the carbon/nitrogen balance were associated with changes in larval growth. This can be attributed to either a lack of defensive capability in the emerging foliage or a failure to measure or manipulate the variables responsible for controlling foliar defense. However, larval growth is only one aspect of plant susceptibility to insects; changing the carbon/nitrogen balance in the grand fir ecosystem may ultimately affect the susceptibility of grand fir to western spruce budworm by changing the balance between plant growth and levels of plant herbivory.

Pre-commercial Thinning in Black Spruce
Pre-commercial Thinning in Black Spruce

Author: Ontario. Northwest Science & Technology

Publisher: Thunder Bay, Ont. : Northwest Science & Technology

Published: 1997

Total Pages: 16

ISBN-13:

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Begins with a literature review on the habitat, reproduction and establishment, and stand development of black spruce. This is followed by a review of thinning as a silvicultural system, and thinning of black spruce in particular. Concludes with a report of a case study of the growth response of black spruce to various levels of thinning. The study area had been burned by wildfire and is located in the Tyrol Lake Demonstration Forest near Lake Nipigon, Ontario.

The Ecology and Silviculture of Mixed-Species Forests
The Ecology and Silviculture of Mixed-Species Forests

Author: M.J. Kelty

Publisher: Springer Science & Business Media

Published: 2013-03-09

Total Pages: 292

ISBN-13: 9401580529

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Much of the world's forested land is dominated by mixed-species stands. Understanding the complex structure and dynamics of these mixtures is a necessary step in the process of formulating appropriate silvicultural systems for their management. David M. Smith, Professor Emeritus of Silviculture at Yale University, has devoted much of his career to the study of the structure, development, and silvicultural treatment of these kinds of stands. This volume is presented by Professor Smith's collegues to honor the contributions he has made to the field. It contains both reviews of past work and results of current studies of mixed stands: topics range from analysis of forest dynamics in unmanaged stands to studies of silvicultural systems applied to mixtures, with examples drawn from boreal, temperate, and tropical regions. Much of the work stresses the importance of understanding the characteristic growth patterns of individual species within mixed stands, and how species interactions shape developmental patterns.