Use of Replacement Vegetation for Control of Competing Vegetation in Spruce Plantations in the BWBS Roderick Negrave B.C. Ministry of Forests Prince George Forest Region Richard Kabzems B.C. Ministry of Forests Prince George Forest Region Introduction Site Descriptions and Methods The most consistent control of competing vegetation Two sites were established during the 1992 growing in northeastern B.C. has been achieved through use season. The Muskwa site is located on a terrace of of the herbicide glyphosate. As an alternative to the the Muskwa River five km south of Fort Nelson. This use of this herbicide, an experiment using seeded site is in the BWBSmw2/05 (white spruce-currant- agronomic forage species to displace competing horsetail) site series and has silty loam–sandy loam vegetation in Picea glauca (white spruce) plantations alluvial soils. Common plant species in 1992 included in northeastern British Columbia was initiated in Populus balsamifera ssp. balsamifera (balsam poplar), 1992. The objectives of this study are as follows: Rosa acicularis (prickly rose), and Calamagrostis 1)␣ to determine the effectiveness of vegetation control canadensis (bluejoint). The Johnson Creek site is using replacement with agronomic species; and 2) to located 14 km southwest of Hudson’s Hope. This assess survival and initial growth of white spruce site is in the BWBSmw1/01 (white spruce/aspen- seedlings on sites that have been mechanically site stepmoss) site series and has loamy soils developed prepared and seeded with agronomic species. on morainal deposits. Common plant species in 1992 127 Integrated Forest Vegetation Management: Options and Applications were Rubus idaeus (red raspberry), Rubus parviflorus Results and Discussion (thimbleberry), Calamagrostis canadensis (bluejoint), Mertensia paniculata (tall bluebells), and Epilobium In 1993, cover and heights of the agronomic species were angustifolium (fireweed). Both of these locations were generally higher at the Muskwa site (Table 1.) The better mechanically site prepared. The Muskwa site was sheared establishment and initial growth of most agronomic species and piled in January 1992. The Johnson Creek site was at the Muskwa site is likely due to: 1) better moisture and sheared and piled in March 1991, then treated with a nutrient availability; and 2) better seedbed. Madge rotary plough in August 1991. The two sites were planted with white spruce stock in 1992, Muskwa in June The intense churning and mixing of the Madge rotary and Johnson Creek in July. plough creates many air spaces, making the seedbed more prone to desiccation. The growth potential and winter A randomized block design was used at each site, with survival of the legumes at Muskwa may have been reduced species seeded as the main plot factor. Species seeded were by an extreme frost in August 1992, the establishment year. Festuca rubra cv. ‘Boreal’ (red fescue), Festuca saximontana cv. ‘Nakiska’ (sheep fescue), Lotus corniculatus cv. ‘Leo’ At both sites, a significant treatment effect existed for both (birds-foot trefoil), Medicago sativa cv. ‘Rangelander’ heights and covers of a number of species that regenerate (alfalfa), Trifolium hybridum cv. ‘Dawn’ (alsike clover), and from seed and rhizomes, including bluejoint and fireweed. Trifolium repens cv. ‘Grasslands Huia’ (white clover). Within However, most of these were herbaceous rather than woody each 0.02 ha plot, ten randomly selected seedlings were species. Exceptions were red raspberry at Muskwa and used as centres for subplots (1 m diameter). Seedling thimbleberry at Johnson Creek. The most impressive damage, mortality, height, current height increment, basal exclusion of native vegetation was in the alfalfa, alsike clover, diameter, and crown radius were recorded. Vegetation and birds-foot trefoil treatments at Muskwa and the alsike species, absolute cover, and height were recorded. Analysis treatment at Johnson Creek. of variance was used to test for differences between At the Muskwa site, the lush growth of alsike clover, birds- treatments (alpha of 0.01). Results presented here are from foot trefoil, and alfalfa caused extensive vegetation press data collected in August 1993. damage to the white spruce seedlings. At Johnson Creek, only the alsike clover caused noticeable vegetation press damage. Table 1. Mean cover and height of agronomic species Muskwa Johnson Creek Cover (%) Height (cm) Cover (%) Height (cm) Alsike clover 26.9b 62.0ab 35.2a 56.8a Alfalfa 47.0a 63.7ab 2.5b 45.0ab Birds-foot trefoil 8.7c 53.9ab 11.6b 41.8ab Red fescue 11.0bc 49.9cd 3.6b 41.7ab White clover 9.7c 34.4cd 5.3b 28.6b Sheep fescue 4.0c 26.9d 1.7b 23.7bc Control 0.0c 0.0e 0.0b 0.0c Identical letters in the same column indicate no significant difference (alpha = 0.01) as determined by Scheffe’s test. 128 Integrated Forest Vegetation Management: Options and Applications Conclusions These initial results suggest that, on highly productive sites, vigorous growth of alfalfa, birds-foot trefoil, and alsike clover may damage seedlings and possibly reduce survival compared to the fescues and white clover. On average upland sites, the growth of alsike clover may also result in seedling damage from vegetation press. However, spruce seedlings may recover from the damage and experience less vegetative competition once they are above the canopy created by the agronomics. After two seasons of growth, agronomic species indicated an ability to reduce the cover and height of some species of native vegetation. 129 COAST Rx: A Conceptual Model of a Decision Support System for Regenerating Oregon’s Coast Range L.J. Shainsky S.A. Knowe Oregon State University Oregon State University Department of Forest Science Department of Forest Science Management activities during early stages of A series of menus is designed to prompt clients for succession are critical to the long-term trajectories site-specific information, management objectives and of Pacific Northwest forests. Competitive effects from constraints, and desired future conditions. Site Set- vegetation, animal damage, and climatic events pose up allows the client to input climate, plant association, the most frequent limitations to productivity of and soil information, as well as perceived hazards, regenerating trees. While much is known about these constraints, and objectives. These settings form the factors and processes, information on them have never foundation for the simulation as well as specifiying been integrated or synthesized into an accessible and the desired future condition. Harvest Set-up useful form. Coast Rx is a decision support system customizes the initial harvesting scenario. Post designed to: 1) integrate and compile information Harvest Set-up customizes the initial choice of post- on the physical and biological factors and processes harvest management activities. Vegetation Scenario important to the regeneration process; 2) use this Evaluation then proceeds by simulating growth of information to model regeneration; and 3) prescribe trees and other plants in the system, as modified by management options for improving regeneration site features and initial management events. Output success. Coast Rx focuses on modeling the first five from this module is passed to a young stand model years of forest development, and interfaces with young for further stand projections. The output from this stand models for projecting tree growth and yield later model—predicted future conditions—is compared to in forest development. desired future conditions. If criteria specified by the client are met, then the initial set of management The principal state variables modeled include activities is verified as acceptable. If criteria are not diameter and height of tree species, and cover and met, a new set of management activities are selected, height of shrubs, herbs, and forbs. Supporting state the vegetation scenario is simulated again and variables also modelled include aerial resources and evaluated as before. This process continues until a conditions such as radiation and humidity and soil set of management activities is formulated that result resources. Competition between trees and their in a match of predicted future conditions with desired associate vegetation is the predominant process future conditions. simulated. Hazards such as the potential for animal, wind, frost, and drought damage are incorporated into predictions of regeneration success. 131 Forest Herbicide Use and Small Mammals Thomas P. Sullivan University of British Columbia Department of Forest Sciences Three relatively long-term studies on the influence 1988–1989 (post-treatment years), and in 1991–1992 of forest herbicide use on small mammals have been (fourth and fifth post-treatment years). Shrub layers conducted in British Columbia: 1) the small mammal were significantly reduced on all study areas after community in a coastal western hemlock forest in treatment. Herbaceous vegetation layers recovered to south coastal B.C.; 2) small mammal community and control levels of biomass by two to three years post- vegetation changes; and 3) snowshoe hare populations treatment. Small mammal (deer mice and red-backed and vegetation changes in Sub-Boreal Spruce (SBS) voles, Clethrionomys gapperi) populations in herb forest near Prince George. stages followed the recovery of vegetation. However, there were no consistent differences in small mammal In terms of the response to habitat change in the south populations between control and treatment shrub coast study, there