Silviculture systems

Silviculture research trials have been established in a variety of different ecosystems throughout the province.

These trials have generated a wealth of data and information on the impacts of the various silvicultural systems on harvesting costs, growth and survival of planted and naturally regenerated seedlings, advanced regeneration, and residual trees, as well as wildlife values, biodiversity and coarse woody debris, levels of vegetative competition, and forest health agents.

Effects of Early Aspen Competition on Lodgepole Pine and Hybrid White Spruce Performance over 35 Years in Central British Columbia - TR153

Forest managers seeking to establish and manage mixedwood stands require information on competitive interactions between tree species, especially over relatively long periods of stand development. We analyzed 35 years of tree and stand development in an even-aged forest in central British Columbia to elucidate long-term  competitive interactions between trembling aspen (Populus tremuloides Michx.) and two conifer species: lodgepole pine (Pinus contorta Dougl. Ex Loud. var. latifolia Engelm.) and hybrid white spruce (Picea glauca (Moench) Voss × Picea engelmannii Parry). At high densities, aspen exerted a strong competitive effect on conifer trees and reduced their height and diameter growth for decades. Lodgepole pine height and diameter growth responded more sensitively to aspen competition than did spruce. Stand modelling suggested that the effects of early aspen competition will persist over the entire rotation of the stand. The effects of aspen competition on conifer growth remain unclear at relatively low aspen densities; therefore, we recommend this be studied further to identify potential density thresholds below which aspen may have low or acceptable effects on conifer yields.

Ecological and Genetic Differentiation between Hybrid Spruce Populations in the Nass Skeena Transition Region in Northwest British Columbia - TR152

he Nass Skeena Transition region (NST) in northwestern British Columbia is an area of extreme geographic and environmental variability. Within this area, the natural ranges of Sitka spruce (Ss) and interior spruce (Sx) merge to form extensive natural hybrid swarms. These complex hybrid populations, together with the extreme geographic and environmental variability of the area, result in populations with high levels of genetic diversity within and among local populations. Selection pressures on young trees, including leader weevil (Pissodes strobi Peck) attack and frost damage, combined with abundant variation in early growth potential, have a strong influence on the health and adaptability of spruce trees in this area. Two series of field trials were analyzed: the older EP702 IUFRO provenance trials, and EP1072, which is composed of nine test sites with 200 populations sampled throughout the NST. Recent molecular investigations of this material were also reviewed. 

Hydraulic Response in Mature Interior Douglas-fir Retained in Clearcuts in Central British Columbia - TR134

Live, mature, interior Douglas-fir (Pseudotsuga menziesii var. glauca [Beissn.] Franco) leave-trees dispersed throughout cutblocks after harvesting show inconsistent survival in the Sub-Boreal Spruce biogeoclimatic zone of central British Columbia. Government policy is to maintain appropriate levels of leave trees on cutblocks to meet provincial biodiversity objectives. Douglas-fir is retained because its populations are naturally fragmented at the northern edge of its natural distribution. In historical disturbance regimes, dominant and veteran Douglas-fir trees that survive fire persist to ages of 300–500 years, while younger cohorts of spruce, lodgepole pine, subalpine fir, and Douglas-fir often establish beneath them, which makes Douglas-fir ecologically an appropriate candidate as a leave-tree. Water relations for large and/or old Douglas-fir trees retained after harvesting were measured by sampling typical mature Douglas-fir leave-trees in a clearcut (CC) and an adjacent unharvested (UN) unit at two sites that differed in age since harvest: one was harvested in 1998, the other in 2003. Xylem water potential and micro-environmental data for soil and evaporative demand suggest that differences in water relations between treatments and sites may be contributing factors in leave-tree mortality. 

Application of Uniform Shelterwood Silvicultural Systems in the Sub-Boreal Spruce Biogeoclimatic Zone in Central British Columbia - TR131

The uniform shelterwood systems trial in the Dry Warm Sub-Boreal Spruce biogeoclimatic subzone of central British Columbia was initiated in 1990 to establish and grow natural Douglas-fir (Pseudotsuga menziesii var. glauca) regeneration on frost-prone sites. In the 1980s, variable performance of Douglas-fir plantations after clearcutting led to reforestation with lodgepole pine (Pinus contorta var. latifolia) as a primary species. Widescale conversion of prime Douglas-fir growing sites was both a long-term economic and biological concern for land managers. 

Silviculture Treatments for Ecosystem Management in the Sayward (STEMS) Establishment and Progress Report for STEMS 3, Gray Lake - TR114

This technical report describes the establishment and 6-year results of the third replication of STEMS in 2008 near Gray Lake. Ongoing studies at STEMS 3 include the following: tree growth and stand development of residual trees and planted and natural regeneration; windthrow, mortality, and coarse woody debris recruitment; harvesting production and effects of residual tree damage and soil disturbance (in partnership with FPInnovations). The results of this experiment will be used to improve forest management and policies because results can be directly interpreted operationally due to the large-scale, replicated experimental design. The information will be especially relevant for forests with multiple-use objectives.

Ten-year Survival and Growth of Planted Conifers in a Group Selection Silvicultural System - TR107

The Mount Tom adaptive management trial was initiated in 1999 to assess whether group selection silvicultural systems, conducted at an operational scale, could maintain attributes of mountain caribou (Rangifer tarandus caribou) winter habitat in high-elevation Engelmann spruce–subalpine fir (ESSF) forests of east-central British Columbia (Waterhouse 2011). This study is a continuation of previous findings from a more tightly controlled silvicultural system research study in the Quesnel Highland (qh) (Newsome et al. 2016a). A key component of maintaining caribou habitat is regeneration of conifers after harvest. Seedling survival and growth in ESSF forests is thought to be limited by duration of snowpack, length of growing season, cold air, and low soil temperatures. 

Examining the potential of western larch, Siberian larch, and ponderosa pine as regeneration species in Cariboo Region ecosystems: 22-year results from EP904.02 - TR96

Experimental Project 904.02 (EP904.02) was established in 1987 to examine the performance of western larch (Larix occidentalis), Siberian larch (Larix sibirica), and ponderosa pine (Pinus ponderosa) at ICHwk2, SBSmw, ESSFwk1, and SBPSxc sites in the Cariboo Region. Survival and growth of these non-native species over a 22-year period were compared with that of lodgepole pine (Pinus contorta var. latifolia), Douglas-fir (Pseudotsuga menziesii), and hybrid spruce (Picea engelmannii × glauca), which are common forest components in this region. Subsequent to the installation of this experiment, climate change-related forest health issues became an important management concern, and the extension of species beyond their natural range was considered as a mitigation strategy. Western larch was a good candidate for assisted migration, and interim guidelines are now in place that allow this species to be planted in many Cariboo Region ecosystems. As a result of these recent changes, our 22-year western larch results are especially relevant to current forest management.

Arboreal Lichen Response to a Group Selection Silvicultural System, Mount Tom Adaptive Management Trial, Central British Columbia - EN113

Southern Mountain caribou (Rangifer tarandus caribou) have been assessed as endangered by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) so strategies and actions for protection and recovery are required under the federal Species at Risk Act. In the Cariboo Region, the Cariboo Chilcotin Land Use Plan (CCLUP) identified areas of caribou habitat for "no-harvest" and "modified harvest". The adaptive management trial at Mount Tom, near Wells, British Columbia was designed to learn how to efficiently implement the group selection silvicultural system at an operational scale and to systematically measure the changes to habitat. Between 2001 and 2010, five blocks (comprising a total of 1040-ha) were harvested using a variety of harvesting equipment, opening designs, and trail layouts. The first entry of the group selection silvicultural system removed one third of the trees (and arboreal lichen) in irregular shaped openings (0.1 - 1.0 ha) throughout each block. Arboreal lichen was measured pre-harvest and at 2.5 and 5.5 years post-harvest in three harvest blocks and two no-harvest controls. Lichen abundance initially decreased at 2.5 years in the partial cuts relative to controls but the difference was no longer significant at 5.5 years.

Natural regeneration in partial cuts and mature forests after mountain pine beetle infestation in the west Chilcotin: Itcha-Ilgachuz Research Project - TR88

The Itcha-Ilgachuz Research Project was initiated in 1995 in the west Chilcotin region of central British Columbia to test variants of group selection and irregular group shelterwood silvicultural systems for managing lodgepole pine (Pinus contorta var. latifolia) forests for timber and northern caribou (Rangifer tarandus caribou Gmelin, northern ecotype) winter habitat. The density, distribution, and growth of naturally regenerated lodgepole pine was monitored in the small harvested openings and the forested matrix of the silvicultural systems treatments, in forested control units, and in adjacent clearcuts over the course of the mountain pine beetle epidemic (2003-2008) and 5 years after.

Natural regeneration in the very dry, cold Sub-Boreal Pine-Spruce (SBPSxc) biogeoclimatic subzone was sufficient to restock small harvested openings and produce a stocked stand in the understorey of a mature stand that was severely impacted by mountain pine beetle. In this subzone, advance regeneration will play an important role in future stand development, more so than ingress resulting from disturbance. In the higher elevation very dry, very cold Montane Spruce (MSxv) subzone, natural regeneration was not abundant enough to stock harvested openings or mountain pine beetle impacted stands. Post-disturbance ingress will be the predominant component of the understorey in this subzone. Our results suggest that recovery after the beetle outbreak will be a slower process in the MSxv than in the SBPSxc due to reliance on new recruits. Better seedling growth and condition in the MSxv, however, may help mitigate the slower recovery rate. The forest canopy, even with considerable mortality, had a significant impact on seedling growth and condition compared to clearcut conditions. The last assessment, completed 5 years after the outbreak, showed that seedlings in all locations, but particularly in the harvested openings, had improved growth and vigour, which suggests that they are responding to the increased site resources. This study shows that pathways of stand recovery after the mountain pine beetle epidemic in the west Chilcotin will differ depending on biogeoclimatic and pre-epidemic stand conditions.

A 20-year Analysis of Incremental Silviculture in Mixed Western Hemlock−Sitka Spruce Stands in the Coastal Western Hemlock Biogeoclimatic Zone- EN114 Zone

Mixed second-growth stands of western hemlock (Tsuga heterophylla) (Hw) and Sitka spruce (Picea sitchensis) (Ss) comprise nearly half of the timber harvesting land base on Haida Gwaii, and are representative of other second-growth mesic sites within the Coastal Western Hemlock (CWH) biogeoclimatic zone in British Columbia. Intensive silviculture was strongly supported by government sponsored forestry programs in the 1980s and 1990s. To monitor the effectiveness of these programs, an experiment (EP1097) consisting of a series of juvenile spacing and fertilizer treatments was established on Graham Island, B.C. in 1991. While major policy change has led to a sharp decline in intensive silviculture in British Columbia and an end to juvenile spacing on Haida Gwaii since the late 1990s, spaced stands are currently prioritized for harvest on Moresby Island. Given the degree to which mid-term Hw/SS stands in the CWH are to be relied upon for harvesting, results from this long-term 1991 study can be used to guide local management practices. This report documents the growth and yield of intensive silviculture treatments in naturally regenerated mixed Hw/Ss stands after 19 years, and the future economic benefits of those treatments.

Growth, Survival, and Microclimate of Conifers Planted within Forest Gaps: Results for the First Five Growing Seasons - TR77

This report describes the establishment of three 0.5-ha gaps and the measurement of two until the end of the 2010 growing season. Three study sites were established on eastern Vancouver Island to explore the effect of stand edge on the growth of four species of conifers with different shade tolerance rankings. One light study gap was planted at the Snowden Demonstration Forest (GS10) in 2004, another near Elk Bay (HU10) in 2006, and a third at Gray Lake (PP10) in 2009. All study sites are within 40 km of Campbell River. Funding restrictions prevented light estimates from being made at the Gray Lake site; therefore, only growth measurements have been possible at that site. At GS10 and HU10, the light environment of each seedling was characterized using hemispherical photographs. In addition, instruments were installed to measure transmittance of above-canopy light (T), temperature, rainfall, soil moisture, and vapour pressure deficit across both gaps. Data for at least five growing seasons (April 1 - October 31) are presented for both sites. Maximum T at GS10 and HU10 was approximately 0.8 and 0.7, respectively, and minimum levels in the understorey declined to less than 0.05 at both sites on the south side of the gaps. Growth on the sites was affected by both soil moisture and vapour pressure deficit. An additive model was used to incorporate the moisture variables with T estimates to model the effect of light on growth, although replication was considered insufficient for statistical comparisons between the two sites. Growth tended to increase to a maximum at T values of approximately 0.3 and 0.8 for western hemlock (Tsuga heterophylla [Raf.] Sarg.) and western redcedar (Thuja plicata Donn.), respectively, and did not reach a maximum at approximately 0.8 above-canopy light for Douglas-fir (Pseudotsuga menziesii [Mirbel] Franco) and western white pine (Pinus monticola Dougl.). Light modelling with TASS III revealed both differences and similarities between the modelled values and estimates derived from hemispherical photos.

Treefall in the Mount Tom Group Selection Silvicultural Systems Trial in Central British Columbia - EN109

Mountain caribou (Rangifer tarandus caribou) are both provincially and federally listed as Threatened. British Columbia has 98% of the entire global population of this ecotype (approximately 1900 animals) (Hatter 2006). These caribou require older forests in the Engelmann Spruce–Subalpine Fir biogeoclimatic zone (ESSF) because arboreal lichens (winter forage) are often abundant in the tree canopies. Clearcut harvesting not only removes arboreal lichens, but also a condition of low lichen abundance could persist for more than a century in the regenerated forest (Stevenson et al. 2001). On the other hand, the group selection silvicultural system provides continuous lichen-bearing habitat through space and time (Waterhouse et al. 2007).

User-friendly web tool to support silviculture for sitka spruce on the south coast - EN95

Pissodes strobi, the terminal weevil that preferentially attacks leaders of Sitka spruce between 2 and 15 m tall, has become a major deterrent to selecting this species for reforestation. Successful weevil attacks kill the leader and a lateral shoot takes over, forming a crook in the stem. Repeated and severe attacks prevent seedlings from reaching free-growing status, and render trees unmerchantable due to bole defects. However, trees may recover from less severe attacks and attain good form upon maturity. Weevil hazard is therefore better indicated by the severity of the effects on form than by the number of attacks. Decades of research and tree improvement have culminated in available terminal weevil resistant Sitka spruce seed for reforestation. Foresters can expect fewer than half the attack levels of local wild stands from bulk seedlots from the superior provenances Haney and Big Qualicum, and over 80% reduction from class A orchard seed (King and Alfaro 2009). The objective of this study was to develop a user-friendly, accurate web tool that foresters could use to support reforestation prescriptions for sites on Vancouver Island where Sitka spruce is an appropriate species.

The Pothole Creek Study Area: Dry Uneven-aged Douglas-fir Stand Development - EN85

Dry uneven-aged interior Douglas-fir (Pseudotsuga menziesii var. glauca [Beissn.] Franco) is a highly variable forest type in the southern interior of British Columbia. Interior Douglasfir stand disturbance history can be complex, resulting in a broad range of stand structures and development pathways. With the mountain pine beetle devastating interior lodgepole pine forests, the importance of understanding the management and potential of other local forest types, such as dry Douglas-fir, is increasing. The Stand Modelling Group of the British Columbia Ministry of Forests and Range Research Branch started work in a partially cut, multi-cohort dry Douglas-fir stand at Pothole Creek in 1996. The purpose was to study the biology of interior Douglas-fir tree and stand growth, to better understand uneven-aged stand development, and to develop growth and yield models (http://www.for. gov.bc.ca/hre/pothole/). This Extension Note presents stand history, regeneration, and growth and yield information gleaned from 10 years of measurements at the Pothole Creek Study Area. The site is typical of the interior Douglas-fir problem forest type, for which more growth and yield information is needed (Snetsinger 2005).

Tools to Help Forest Managers with Regeneration Decisions about Beetle-killed Stands in the Montane Spruce Zone of the Merritt Timber Supply Area - EN83

Forest managers will have to make decisions regarding regeneration strategies for mountain pine beetle– attacked stands because not all attacked stands will be salvaged. We developed tools to help forest managers make these decisions in the Montane Spruce zone in the Merritt Timber Supply Area. Our tools predict the abundance and spatial distribution of advance regeneration in attacked stands. For ease of use, these models are available as an Excel computer program.

Silvicultural Systems on a Deep Snowpack, Mule Deer Winter Range in the Central Interior of British Columbia: 10-year Update - EN89

In the Horsefly variant of the moist, cool Interior Cedar-Hemlock (ICHmk3) biogeoclimatic subzone, within the central interior of British Columbia, Douglas-fir (Pseudotsuga menziesii) tends to occur in even-aged stands. Douglas-fir forests are important from both the forest industry and wildlife habitat management perspectives. In this ecosystem, Douglas-fir can be clearcut and regenerated through planting mixes of lodgepole pine (Pinus contorta), interior spruce (Picea glauca x engelmannii), and Douglas-fir, but this practice seriously compromises habitat value as mule deer winter range. Deer require mature and older Douglas-fir stands as winter range to reduce the snowpack and provide forage (Waterhouse et al. 1994), especially foliage from larger trees (Dawson et al. 1990). This project was initiated in 1996 to test silvicultural systems options for the management of mule deer winter range in the transition to deep snowpack zones. This represents about one-quarter of the identified winter range within the Cariboo-Chilcotin land use planning area (Dawson et al. 2006).

The Opax Mountain Silvicultural Systems Project: Preliminary Results for Managing Complex, Dry Interior Douglas-fir Forests - EN72

The Opax Mountain Silvicultural Systems project explores management options for some of the issues facing managers of complex forests in the dry Interior Douglas-fir (IDF) biogeoclimatic zone. The project includes two study areas: one in the IDFxh2 variant and one in the IDFdk2. Each area has six operational-scale harvest treatments: uncut control; 20% removal of merchantable volume using individual tree selection (ITS); 50% ITS; 50% ITS with uncut reserves; 20% removal using a mixture of patch cuts of 0.1, 0.4, and 1.6 ha; and 50% removal with patch cuts of a similar nature as the 20% removal.

The project includes studies of:
- fire history and other natural disturbance agents;
- regeneration in openings and under partial canopy;
- edge effects on microclimate, snowmelt, and soils;
- effects of canopy density, gap sizes, site preparation, and edges on planted seedlings, natural regeneration, and vegetation (including cover layers, individual species, and groups such as forage plants, weeds, soil seedbanks, and ectomycorrhizal hosts); and
- harvest treatment effects and habitat relationships of wildlife groups, including terrestrial invertebrates, arboreal beetles, small mammals, songbirds, woodpeckers, and ungulates.

Microclimate Studies in Silvicultural Systems on the Chilcotin Plateau of British Columbia The Itcha–Ilgachuz Project (1997–2003) - EN22

Group selection and irregular group shelterwood silvicultural systems are being tested as options to conserve woodland caribou (Rangifer tarandus caribou) habitat. If successful, the systems will be applied within the very dry, cold SubBoreal Pine–Spruce (SBPSxc) and very dry, very cold Montane Spruce (MSxv) biogeoclimatic subzones, located on the high-elevation Chilcotin Plateau of west-central British Columbia. In these harsh growing environments, partial cutting strongly influences the microclimate in terms of air and soil temperature, frost events, and snow-free dates.

The Effect of the Silviculture Survey Parameters on the Free-Growing Decision Probabilities and Projected Volume at Rotation - LMH50

This handbook discusses the silviculture survey system used by the B.C. Ministry of Forests to assess stands for free-growing status. The silviculture survey system is reviewed, and the decision curve as a statistical tool to assess risk is explained. Decision curves are used to explore the effects of changes to survey parameters, as determined by a simulation study of homogeneous stem maps.

Projected volumes for homogeneous lodgepole pine stands (based on TASS, a growth and yield model) are also presented and discussed. The simulation study did not investigate the effects of disease, infestation, or brush competition on volume: all trees were assumed to be healthy and unimpeded by vegetation.

Natural Regeneration 10 Years after Partial Cutting in a Dry-belt Interior Douglas-fir Stand - EN68

We often assume that partially cut stands will regenerate naturally, but patterns and amounts of natural ingress are hard to predict. Dry-belt Douglas-fir stands of British Columbia’s southern interior have been partially cut for decades, but there is still very little reliable information on regeneration rates and the effects of different amounts of residual stocking. A greater understanding of the regeneration response to partial cutting will help silviculturalists anticipate what contribution natural ingress might make to future stocking, and assist with the ongoing development of stocking guidelines for partially cut stands.

Comparing Clearcutting and Alternatives in a High-elevation Forest: Early Results from Sicamous Creek - EN63

The Sicamous Creek Silvicultural Systems project examines clearcutting and silvicultural alternatives to clearcutting in high elevation Engelmann spruce - subalpine fir (ESSF) forests, motivated by concerns about the effects of forestry practices on regeneration, hydrology, and biological diversity.

This note summarizes the results of studies that have looked at harvest treatment effects and the effects of different opening sizes on 50 different resource values and ecosystem components.

Edge Effects in High-elevation Forests at Sicamous Creek - EN62

Edge effects are increasingly important in British Columbia forests, as cut blocks become smaller and harvesting options with retention patches are more commonly used. This note summarizes edge effects for 21 ecosystem variables, including microclimate, soil chemistry, snow depth, windthrow, regeneration, vegetation, and animals, at the Sicamous Creek Silvicultural Systems project in a high elevation ESSF forest.

Ultraviolet-B Radiation Impacts on Tree Seedlings in British Columbia - LMH49

This report provides some background information on the thinning ozone layer and how UV-B affects plants, summarize the logistics of UV-B exposure studies, and shows results for each tree species studied. It also provides an initial ranking of UV-B sensitivity, compares these results to those of other studies, and makes recommendations for future directions.

Silviculture Prescription Data Collection Field Handbook: Interpretive Guide for Data Collection, Site Stratification, and Sensitivity Evaluation for Silviculture Prescriptions - LMH47

This guide is a technical support document intended to help forestry practitioners collect the information they need to prepare a silviculture treatment regime and silviculture prescription in accordance with Forest Practices Code legislation. It deals primarily with the collection and stratification of site-specific field data. It has been designed to promote consistent collection of field data on Field Forms FS 39A and FS 39B. This guide is not meant to be a substitute for education, training, or experience in the field.

The use of this guide is not a statutory requirement and much of the data described in it is not directly required by legislation. An individual practicing due diligence, however, will collect appropriate information to develop site-specific prescriptions and the accompanying forms have proven quite popular for this data collection.

Skid Road Recontouring in Southeastern British Columbia: 7-year Tree Growth Results - TR01

The Forest Practices Code of British Columbia Act (1995) created a legal requirement for soil conservation and, in particular, called for skid road rehabilitation to restore site productivity and slope hydrology. A research trial, initiated in the Nelson Forest Region in 1995, tested the efficacy of rehabilitation practices by quantifying tree growth on rehabilitated skid roads. This technical report presents the 7-year tree growth results of the study.

Sites were planted with lodgepole pine (Pinus contorta), or Engelmann spruce (Picea engelmannii), or both. At eight locations in the Rocky and
Purcell mountains in south-eastern British Columbia, total height, annual height increment, and basal diameter were measured on 1713 trees, which ranged in age from 6 to 10 years.

Undisturbed trees and those on berm locations grew significantly (p<0.05) more than those on inner track and midroad locations at the current
block age for total height, 3-year increment, diameter, and volume for lodgepole pine. At a comparison block age of 7 years, 3-year increment was significantly greater for both undisturbed and berm-grown pine and spruce; additionally berm and undisturbed total height was greater for spruce. The growth of inner track pine trees was significantly reduced for all variables at the current block age. Reduced tree growth was most pronounced at sites with calcareous soils.

Continued poorer growth observed on the skid roads in this study supports the FPC requirement for more intensive rehabilitation methods to
restore site productivity. Until it is demonstrated that the construction and rehabilitation of skid roads is sufficient to support acceptable tree growth, net downs to Annual Allowable Cut calculations may be necessary to address reduced tree growth on temporary access structures.

The Silviculture of Hybrid Poplar Plantations - EN47

As demand for wood products and fibre increases, forest managers face the challenge of growing more wood on less land. Shorter rotations and diversification of products may help mitigate this pressure. Hybrid poplars grow quickly. The rotation age ranges from 10 to 26 years in British Columbia depending on a number of factors, including climate, site, and management regime. The more intensive the management, the shorter the rotation. Hybrid poplar is used primarily for pulp, but can also be used for lumber and plywood. Markets for the latter products are developing and need to be encouraged. Non-wood uses include ornamental plantings, soil stabilization, and conservation. In British Columbia, hybrid poplar plantations are being grown in the interior, and on the south coast, mid-coast, and Vancouver Island.

Pinchi Lake Operational Herbicide Monitoring: 10-year Conifer and Vegetation Responses in the SBSdw3 - EN46

In forestry, vegetation management treatments are widely used to enhance establishment of young stands and achieve free growing requirements. In 1988, an operational herbicide monitoring trial was established in a 4-year-old white spruce (Picea glauca) and Douglas-fir (Pseudotsuga menziesii) plantation in the SBSdw3 biogeoclimatic zone to examine the effectiveness of glyphosate herbicide on a vegetation community. The study consists of two 1 ha treatment plots, one of which was treated with glyphosate once using a backpack sprayer at a rate of 1.8 kg a.i./ha. Ten years after treatment, glyphosate had increased basal diameter and crown radius, reduced height-to-diameter ratio, and improved vigour of white spruce. Fourteen years after planting, the glyphosate treated plot had significantly greater number of free growing spruce per ha. The treatment also increased conifer and herb percent cover, and reduced broadleaf and shrub percent cover. However, the treatment did not affect the plant species richness. Yield projections for conifers and broadleaves based on MGM suggest that treatment applied to control broadleaves and shrubs has the potential to increase conifer yield and reduce conifer rotation age.

Opportunities for Improvements to Reforestation Success - EN43

Various issues pertaining to artificial reforestation using coniferous planting stock are presented in the question/ answer format. The discussed topics include: planting into organic soil substrates, microsite selection, planting depth, and closing the planting hole. These topics are viewed in the context of different site-related or climate-associated factors that may limit the successful establishment and growth of planted seedlings. A brief discussion of the literature on basic requirements for seedling growth and survival is also presented.

A Comparison of Mulch Mat and Herbicide Treatments for Reducing Grass Competition in the IDFww - EN27

In the warm wet Interior Douglas-fir biogeoclimatic subzone (IDFww), mechanical and herbicide site preparation and brushing treatments have been used to establish planted conifers. These silviculture treatments have been prescribed to control grass and shrub competition which rapidly develops after harvesting. Many of these sites, especially those with a southern aspect, have experienced poor survival of planted Douglas-fir. Poor plantation establishment has been attributed to poor stock quality and severe grass and shrub competition for soil moisture. Innovative brushing methods are needed for the establishment of Douglas-fir on these dry sites. Herbicide and mulch mat treatments have been used with some success.

Glyphosate herbicide has been widely applied in forestry as an effective vegetation control treatment. Hexazinone herbicide has also been used. Both herbicides have been shown to effectively control grass if applied while the grass is actively growing (Boyd et al. 1985; Fahlmann and Herring 1985). However, conifers are also very sensitive to herbicide application during the active growing period. Consequently, growing-season treatments must be applied either before conifer seedlings are planted (pre-plant application), before conifer growth begins, or the planted seedlings must be protected during application.

Differences in Early Conifer Performance in Young Seral Vegetation of the CWHdm Subzone - EN06

Non-crop vegetation on regenerating forest lands is often viewed as being uniformly detrimental to the establishment and growth of commercial tree species. This assumption is ingrained in our traditional concepts of land stewardship and efficient commodity production. The "free-growing" designation for a regenerated stand defines the extent of basic silviculture for which forest licensees are responsible in British Columbia, and the free-growing definition requires that crop trees be taller than all surrounding vegetation, regardless of species. Such a policy may represent an inappropriate extension of agricultural paradigms to silviculture, for evidence is mounting that (1) not all effects of vegetation are negative, and (2) different plant species are not equivalent in their effects.

An experiment was undertaken in the UBC Malcolm Knapp Research Forest near Maple Ridge, B.C., in order to measure the competitive effects of the dominant, non-crop, plant species found in early, post-logging, successional vegetation. This work quantifies some of the impacts of different plants described by Haeussler et al. (1990) in their review of the earlier literature. The study was conducted on two cutblocks in the dry maritime subzone of the Coastal Western Hemlock biogeoclimatic zone (CWHdm); results may or may not be more widely applicable.

Nitrogen Limits on the Early Growth of Shade-tolerant Regeneration on a Coastal Montane Site - EN05

Growth of shade-tolerant tree species regenerating on coastal montane forests is often delayed or inconsistent following stand removal (Herring and Etheridge 1976). This may have a long-term impact on the productivity of these sites, upon which the region's future timber supply increasingly relies. Restricted availability of nutrients, particularly nitrogen, may limit growth of shade-tolerant regeneration in high-elevation coastal forests in which low concentrations of foliar nitrogen have been reported (Gessel and Klock 1982; Radwan et al. 1989).

In an earlier study on a coastal montane reforestation site, we reported on 1-year-old planted amabilis fir stock that was chlorotic and had reduced photosynthetic rates compared to its natural counterparts released 4 years earlier (Koppenaal et al. 1995). Those findings prompted this study, in which we compared foliar concentrations of nitrogen (N) and phosphorus (P) in relation to the post-harvest growth of planted and advance regeneration of amabilis fir and western hemlock. The impact of stand removal on seedling microclimate is known to affect photosynthetic rates (Koppenaal et al. 1995) as well as decomposition rates and nutrient availability (Edmonds et al. 1989). In an effort to determine the influence of post-harvest light environment on nutrient status and productivity, we further compared foliar N and P concentrations and growth between clearcut and stand edge microsites.

Vegetation Management Options for Establishment of Hybrid Poplar Plantations and their Effect on Nutrient Cycling - EN25

This extension note provides a brief overview of a study examining the effects of vegetation control on poplar growth and site nutrient cycling. Although some results are presented, this project is still in its infancy and no conclusions are drawn.

The Date Creek Silvicultural Systems Study in the Interior Cedar–Hemlock Forests of Northwestern British Columbia - LMH38

The Date Creek silvicultural systems study was initiated in 1990 Over the past seven years, there has been an extraordinary amount of work done to establish and implement the project. The overall research design resulted from a synthesis of ideas and suggestions provided by the principle researchers as well as Pierre Beaudry, Ian Cameron, Tracy Harmati, Paul Knowles, Will MacKenzie, Christian Messier, Dan Myrah, Jim Pojar, Sandra Thomson, and Rick Trowbridge. Vera Sit and Wendy Bergerud provided statistical advice throughout the development of the project. We are grateful to Norm Bilodeau, Paul Hanna, Tracy Harmati, and others from the Kispiox Forest District who administered the harvesting activities at Date Creek. Chris Clement completed the ecosystem map for the Date Creek research area with the assistance of Ministry of Forests Research staff. Anne Macadam and Bruce Colquhoun provided detailed soil descriptions for representative sites within the study area. John Parminter documented the fire history of the study area.

A Preliminary Guide to the Response of Major Species of Competing Vegetation to Silvicultural Treatments - LMH9

Good vegetation management requires a basic understanding of the ecological characteristics of individual competitors and how they respond to silvicultural treatments. This report documents what is currently known about the response of major species of competing vegetation in British Columbia to various silvicultural treatments now in use. The information has been gathered from a variety of published and unpublished sources, and through conversations with researchers and practitioners in vegetation management in related fields.