Defining tree taper: A challenge for growth and yield modelling in Ontario

The province of Ontario holds approximately 70.2 million hectares of forests: about 17% of Canada’s and 2% of the world’s forests. Approximately 21 million hectares are managed as commercial forests, with an annual harvest in the early part of the decade approaching 200 000 ha. Yield tables developed by Walter Plonski in the 1950s provide the basis for most wood supply calculations and growth projections in Ontario. However, due to changes in legislation, policy, and the planning process, they no longer fully meet the needs of resource managers. Furthermore, Plonski`s tables are not appropriate for the range of silvicultural options now practised in Ontario. In October 1999, the Canadian Ecology Centre- Forestry Research Partnership (CEC-FRP) was formed and initiated a series of projects that collectively aimed at characterizing, quantifying and ultimately increasing the economically available wood supply. Comprehensive, defensible, and reliable forecasts of forest growth and yield were identified as key knowledge gaps. The CEC-FRP, with support from the broader science community and forest industry, initiated several new research activities to address these needs, the results of which are outlined briefly in this paper. We describe new stand level models (e.g., benchmark yield curves, FVS Ontario, stand density management diagrams) that were developed using data collected from permanent sample plots and permanent growth plots established and remeasured during the past 5 decades. Similarly, we discuss new height–diameter equations developed for 8 major commercial tree species that specifically account for stand density. As well, we introduce a CEC-FRP-supported project aimed at developing new taper equations for plantation grown jack pine and black spruce trees established at varying densities. Furthermore, we provide an overview of various projects undertaken to explore measures of site productivity. Available growth intercept and site index equations are being evaluated and new equations are being developed for major commercial tree species as needed. We illustrate how these efforts are advancing Ontario’s growth and yield program and supporting the CEC-FRP in achieving its objective of increasing the supply of fibre by 10% in 10 years while maintaining forest sustainability. Key words: permanent sample plots (PSPs), permanent growth plots (PGPs), normal yield tables, sustainable forest management, NEBIE plot network, forest inventory, Forest Vegetation Simulator

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A Novel Approach to Modelling Stand-Level Growth of an Even-Aged Forest Using a Volume Productivity Index with Application to New Zealand-Grown Coast Redwood

Forests ◽

10.3390/f12091155 ◽

2021 ◽

Vol 12 (9) ◽

pp. 1155 ◽

Cited By ~ 1

Author(s):

Mark O. Kimberley ◽

Michael S. Watt

Keyword(s):

New Zealand ◽

Growth Model ◽

Growth Models ◽

Stand Density ◽

Site Index ◽

Growth And Yield ◽

Productivity Index ◽

Site Quality ◽

Spatial And Temporal Variation ◽

Coast Redwood

Empirical growth models are widely used to predict the growth and yield of plantation tree species, and the precise estimation of site quality is an important component of these models. The most commonly used proxy for site quality in growth models is Site Index (SI), which describes the mean height of dominant trees at a specified base age. Although SI is widely used, considerable research shows significant site-dependent variation in height for a given volume, with this latter variable more closely reflecting actual site productivity. Using a national dataset, this study develops and describes a stand-level growth and yield model for even-aged New Zealand-grown coast redwood (Sequoia sempervirens). We used a novel modelling approach that quantifies site quality using SI and a volume-based index termed the 300 Index, defined as the volume mean annual increment at age 30 years for a reference regime of 300 stems ha−1. The growth model includes a number of interrelated components. Mean top height is modelled from age and SI using a polymorphic Korf function. A modified anamorphic Korf function is used to describe tree quadratic mean diameter (Dq) as a function of age, stand density, SI and a diameter site index. As the Dq model includes stand density in its formulation, it can predict tree growth for different stand densities and thinning regimes. The mortality model is based on a simple attritional equation improved through incorporation of the Reineke stand density index to account for competition-induced mortality. Using these components, the model precisely estimates stand-level volume. The developed model will be of considerable value to growers for yield projection and regime evaluation. By more robustly describing the site effect, the growth model provides researchers with an improved framework for quantifying and understanding the causes of spatial and temporal variation in plantation productivity.

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Light dynamics and free-to-grow standards in aspen-dominated mixedwood forests

The Forestry Chronicle ◽

10.5558/tfc78137-1 ◽

2002 ◽

Vol 78 (1) ◽

pp. 137-145 ◽

Cited By ~ 52

Author(s):

Victor J Lieffers ◽

Bradley D Pinno ◽

Kenneth J Stadt

Keyword(s):

Leaf Area Index ◽

Key Words ◽

Leaf Area ◽

Light Transmission ◽

Stand Density ◽

Canopy Gaps ◽

Light Competition ◽

Area Index ◽

Mixedwood Forests ◽

Key Words Competition

This study examines light competition between aspen and spruce during the sequence of aspen development. Leaf area index and light transmission were measured or estimated for aspen stands from 2 to 125 years old. Light transmission was lowest at 15-25 years, and in some stands, transmission was less than 5% of above-canopy light. Hypothetical aspen stands with various stem configurations and heights were developed, and positions were identified that would meet or fail Alberta free-to-grow (FTG) standards. Light transmission was estimated at each position with the MIXLIGHT forest light simulator. Positions in canopy gaps or at the northern sides of canopy gaps had higher light. In general, however, there was little difference in available light between positions that met or failed FTG criteria. Stand density and size of aspen trees appears to be a better index to predict light transmission and spruce success in juvenile aspen stands than current FTG criteria. Key words: competition, free to grow, hardwood, spruce, light

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Stand growth responses after fertilization for thinned lodgepole pine, Douglas-fir, and spruce in forests of interior British Columbia, Canada

Canadian Journal of Forest Research ◽

10.1139/cjfr-2019-0188 ◽

2019 ◽

Vol 49 (11) ◽

pp. 1471-1482

Author(s):

Woongsoon Jang ◽

Bianca N.I. Eskelson ◽

Louise de Montigny ◽

Catherine A. Bealle Statland ◽

Derek F. Sattler ◽

...

Keyword(s):

British Columbia ◽

Picea Glauca ◽

Lodgepole Pine ◽

Basal Area ◽

Stand Density ◽

Site Index ◽

Douglas Fir ◽

Picea Sitchensis ◽

Growth And Yield ◽

Growth Responses

This study was conducted to quantify growth responses of three major commercial conifer species (lodgepole pine (Pinus contorta Douglas ex Loudon var. latifolia Engelm. ex S. Watson), interior Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. glauca (Beissn.) Franco), and spruce (white spruce (Picea glauca (Moench) Voss) and hybrid spruce (Picea engelmannii Parry ex. Engelm. × Picea glauca (Moench) Voss × Picea sitchensis (Bong.) Carrière))) to various fertilizer blends in interior British Columbia, Canada. Over 25 years, growth-response data were repeatedly collected across 46 installations. The fertilizer blends were classified into three groups: nitrogen only; nitrogen and sulfur combined; and nitrogen, sulfur, and boron combined. The growth responses for stand volume, basal area, and top height were calculated through absolute and relative growth rate ratios relative to a controlled group. Fertilizer blend, inverse years since fertilization, site index, stand density at fertilization, and their interactions with the fertilizer blend were used as explanatory variables. The magnitude and significance of volume and basal area growth responses to fertilization differed by species, fertilizer-blend groups, and stand-condition variables (i.e., site index and stand density). In contrast, the response in top height growth did not differ among fertilization blends, with the exception of the nitrogen and sulfur fertilizer subgroup for lodgepole pine. The models developed in this study will be incorporated into the current growth and yield fertilization module (i.e., Table Interpolation Program for Stand Yields (TIPSY)), thereby supporting guidance of fertilization applications in interior forests in British Columbia.

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Row-spacing and seed-rate effects on winter wheat in Ontario

Canadian Journal of Plant Science ◽

10.4141/cjps93-005 ◽

1993 ◽

Vol 73 (1) ◽

pp. 31-35 ◽

Cited By ~ 15

Author(s):

A. H. Teich ◽

T. Welacky ◽

A. Hamill ◽

A. Smid

Keyword(s):

Winter Wheat ◽

Grain Yield ◽

Key Words ◽

Unit Area ◽

Growth And Yield ◽

Row Spacing ◽

Seed Rate ◽

Weed Growth ◽

Rate Effects ◽

Lamb’S Quarters

This study was carried out to determine if winter wheat in southwestern Ontario should be grown in rows narrower than the conventional 18 cm and if the current recommended seed rate of 3.2 million seeds ha−1 (msh) is adequate. We compared the effect of 10- and 20-cm row spacings and 1.6, 3.2, and 6.4 msh seed rates on grain yield, weed growth and yield of underseeded clover. Row spacing at a constant seed rate did not affect yield. With increasing seed rate there was an increase in yield, mainly through more heads per unit area, which more than compensated for a decrease in seeds per head. Narrow rows reduced the number of lamb’s-quarters and the overall weed count. The optimum seed rate for grain yield was 6.4 msh for ratios of seed cost:crop value less than 1.34. Key words: Narrow rows, weeds, yield, economic optimum

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Incorporating intertree competition into an ecosystem model

Canadian Journal of Forest Research ◽

10.1139/x95-046 ◽

1995 ◽

Vol 25 (3) ◽

pp. 413-424 ◽

Cited By ~ 32

Author(s):

R.L. Korol ◽

S.W. Running ◽

K.S. Milner

Keyword(s):

Process Model ◽

Basal Area ◽

Stand Density ◽

Tree Height ◽

Ecosystem Model ◽

Growth And Yield ◽

Maintenance Respiration ◽

Tree Diameter ◽

Diameter Increment ◽

Individual Trees

Current research suggests that projected climate change may influence the growth of individual trees. Therefore, growth and yield models that can respond to potential changes in climate must be developed, TREE-BGC, a variant of the ecosystem process model FOREST-BGC, calculates the cycling of carbon, water, and nitrogen in and through forested ecosystems. TREE-BGC allocates stand-level estimates of photosynthesis to "each tree using a competition algorithm that incorporates tree height, relative radiation-use efficiency, and absorbed photosynthetically active radiation, TREE-BGC simulated the growth of trees grown in a dense and an open stand of interior Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) near Kamloops, B.C. The competition algorithm dynamically allocated stand estimates of photosynthesis to individual trees, and the trees were grown using an allometric relationship between biomass increment and height and diameter increment. Asymptotic height growth and the changes in the height–diameter relationship with competition were also incorporated in the model algorithms. Sapwood and phloem volume were used to calculate maintenance respiration. Predicted reductions in diameter growth with stand density were similar to those observed in the study stands. Although the carbon balance of individual trees was not tested, simulated tree diameter increments and height increments were correlated with the actual measurements of tree diameter increment (r2 = 0.89) and tree height increment (r2 = 0.78) for the 5-year period (n = 352). Although the model did not work well with trees that had diameters <5 cm, the model would be appropriate for a user who required an accuracy of ± 0.03 m3•ha−1 for volume, ± 0.02 m2•ha−1 for basal area, or ± 0.4 m for tree height over a 5-year period.

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Effect of sowing time and cultivars on the growth and yield of chickpea under rainfed condition

Bangladesh Journal of Agricultural Research ◽

10.3329/bjar.v34i2.5807 ◽

1970 ◽

Vol 34 (2) ◽

pp. 335-342 ◽

Cited By ~ 2

Author(s):

AHM Fazlul Kabir ◽

MN Bari ◽

Md Abdul Karim ◽

Qazi Abdul Khaliq ◽

Jalal Uddin Ahmed

Keyword(s):

Key Words ◽

Growth Yield ◽

Growth And Yield ◽

Sowing Time ◽

Rainfed Condition ◽

Chickpea Cultivars

Key Words: Chickpea; cultivars; sowing time; growth; yield. DOI: 10.3329/bjar.v34i2.5807Bangladesh J. Agril. Res. 34(2): 335-342, June 2009

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Rapid Assessment of Risk Using Stand Density Indices

Western Journal of Applied Forestry ◽

10.1093/wjaf/14.3.149 ◽

1999 ◽

Vol 14 (3) ◽

pp. 149-152

Author(s):

Mark J. Ducey ◽

Bruce C. Larson

Keyword(s):

Relative Density ◽

Sampling Error ◽

Rapid Assessment ◽

Stand Density ◽

Subjective Assessment ◽

Growth And Yield ◽

Exact Methods ◽

Yield Model ◽

Actual Measurement ◽

Density Index

Abstract When management decisions are based on a stand density measure, there is always a risk that sampling error will result in an incorrect management choice. Estimating confidence limits and associated probabilities for many popular stand density measures is computationally difficult, and can require information that is difficult to obtain in practice. Here, we present an alternative method for rapid assessment of risk that is applicable to Reineke's stand density index, Wilson's relative spacing, Drew and Fiewelling's relative density index, and Curtis's relative density. The method requires an independent estimate of stand density, for example, from a growth and yield model or from a subjective assessment before actual measurement. The results, while inexact, are both easier to obtain and more conservative than those obtained by exact methods. West. J. Appl. For. 14(3):149-152.

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Predicting Crown Radius in Eastern White Pine (Pinusstrobus L.) Stands in New Hampshire

Northern Journal of Applied Forestry ◽

10.1093/njaf/24.1.61 ◽

2007 ◽

Vol 24 (1) ◽

pp. 61-64 ◽

Cited By ~ 1

Author(s):

Gregory J. Jordan ◽

Mark J. Ducey

Keyword(s):

New Hampshire ◽

Basal Area ◽

Stand Density ◽

Growth And Yield ◽

White Pine ◽

Eastern White Pine ◽

Forest Inventories ◽

Crown Length ◽

Quadratic Mean Diameter ◽

Using Data

Abstract Using data from 449 trees on 69 growth-and-yield plots located in southern and central New Hampshire, we developed models of crown radius for stand-grown eastern white pine (Pinus strobus L.) in New Hampshire. In addition to dbh, we tested single-tree measurements sometimes collected in forest inventories (such as live crown length and live crown ratio [LCR]), as well as simple variables to compensate for stand density and competitive position of the tree. A model using dbh, stand basal area (BA), and LCR provided the best predictions, but a model using dbh, stand BA, and the ratio of dbh to stand quadratic mean diameter proved nearly as accurate. We compare these equations to previously published equations for white pine.

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Tolerance of annual forage legumes to herbicides in Alberta

Canadian Journal of Plant Science ◽

10.4141/p02-108 ◽

2003 ◽

Vol 83 (3) ◽

pp. 649-652 ◽

Cited By ~ 3

Author(s):

J. Fraser ◽

J. R. Moyer ◽

A. K. Topinka ◽

D. McCartney

Keyword(s):

Key Words ◽

Weed Control ◽

Dry Matter ◽

Stand Density ◽

Dry Matter Yield ◽

Forage Legumes ◽

Berseem Clover

The effects of ethalfluralin, trifluralin, and imazethapyr herbicides were assessed on stand density, visual injury and dry matter yield of annual forage legumes under irrigation. Results indicate that recommended rates o f either ethalfluralin or imazethapyr have potential for weed control in alfalfa, berseem clover, balansa clover, fenugreek, pea, and vetches. Key words:

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