Yield Responses of Black Spruce to Forest Vegetation Management Treatments: Initial Responses and Rotational Projections

Peter F Newton

doi:10.1155/2012/150157

Abstract

The objectives of this study were to (1) quantitatively summarize the early yield responses of black spruce (Picea mariana(Mill.) B.S.P.) to forest vegetation management (FVM) treatments through a meta-analytical review of the scientific literature, and (2) given (1), estimate the rotational consequences of these responses through model simulation. Based on a fixed-effects meta-analytic approach using 44 treated-control yield pairs derived from 12 experiments situated throughout the Great Lakes—St. Lawrence and Canadian Boreal Forest Regions, the resultant mean effect size (response ratio) and associated 95% confidence interval for basal diameter, total height, stem volume, and survival responses, were respectively: 54.7% (95% confidence limits (lower/upper): 34.8/77.6), 27.3% (15.7/40.0), 198.7% (70.3/423.5), and 2.9% (−5.5/11.8). The results also indicated that early and repeated treatments will yield the largest gains in terms of mean tree size and survival. Rotational simulations indicated that FVM treatments resulted in gains in stand-level operability (e.g., reductions of 9 and 5 yr for plantations established on poor-medium and good-excellent site qualities, resp.). The challenge of maintaining coniferous forest cover on recently disturbed sites, attaining statutory-defined free-to-grow status, and ensuring long-term productivity, suggest that FVM will continue to be an essential silvicultural treatment option when managing black spruce plantations.

Highlights

The underlying objective of intensive forest management (IFM) is to increase the intrinsic productivity of the forest land base via the application of an integrated silvicultural regime involving the application of various temporal-spatialspecific treatment matrices encompassing intensive site preparation, plantation establishment including the use of genetically improved stock, eliminating competing vegetation via mechanical, chemical, or biological control mechanisms, continuous and active protection from insects and pathogens, and density management
Numerous case studies of individual experiments have clearly demonstrated the benefits of IFM treatments, collective summaries documenting the response of boreal species are limited
Linear correlation analysis revealed the following significant (P ≤ 0.05) associations: (1) mean effect size for diameter (product-moment correlation coefficient (r) = 0.74) and volume (r = 0.48) increased with increasing TN, and (2) mean effect size for height (r = −0.53) and survival (r = −0.38) decreased with increasing TI. These results suggest that early and repeated forest vegetation management (FVM) treatments will yield the largest gains in terms of mean tree size and survival

Summary

Introduction

The underlying objective of intensive forest management (IFM) is to increase the intrinsic productivity of the forest land base via the application of an integrated silvicultural regime involving the application of various temporal-spatialspecific treatment matrices encompassing intensive site preparation (e.g., mechanical scarification), plantation establishment including the use of genetically improved stock, eliminating competing vegetation via mechanical, chemical, or biological control mechanisms, continuous and active protection from insects and pathogens, and density management (e.g., maximizing product quality and quantity via initial spacing, precommercial thinning, and/or commercial thinning). As part of a larger quantitative synthesis regarding yield responses of boreal conifers to IFM treatments (e.g., tree improvement [2], forest fertilization [3], density management [4]), the objectives of this study were to (1) quantitatively summarize the early yield responses of black spruce (Picea mariana (Mill.) BSP) to forest vegetation management (FVM) treatments through a meta-analytical review of the scientific literature, and (2) given (1), project rotational outcomes of these responses employing a modified variant of the comprehensive growth, yield, and wood quality simulator, CROPLANNER [5, 6]. Without FVM, forest managers may have difficulty in realizing their stand-level timber management objectives given the negative effect of herbaceous and woody competitors on the growth and survival rates of various crop species. The focus of this study was to document the yield consequences of reducing or eliminating interspecific competitors on black spruce, irrespective of the actual control mechanism employed

Objectives

Methods

Results

Discussion

Conclusion