Yields of Southwestern Pinyon-Juniper Woodlands

Abstract Site quality and growth-growing stock relations were developed for southwestern woodlands of pinyon (Pinus edulis) and one-seed juniper (Juniperus monosperma) or Utah juniper (J. osteosperma). Anamorphic height-age site index curves for pinyon were developed from a regional sample of 60 woodlands. Site index was unaffected by variation in stocking and was correlated with woodland yield when used in conjunction with density. Pinyon and juniper PAI, when taken separately, were highly correlated with stand density and pinyon site index. Pinyon was twice as productive as juniper at similar stand densities. Pinyon and juniper yields in woodlands of average density and site index were estimated at 0.29 and 0.15 m3ha-1y-1. At high densities pinyon and juniper yields increased to 0.61 and 0.31 m3ha-1y-1 Pinyon and juniper yields appeared independent of the density of the other species in an individual woodland. Maximum yield of dense mixed species woodlands on average sites was 0.78 m3ha-1y-1, and occurred when pinyon constituted 65% of woodland density. West. J. Appl. For. 3(3):70-74, July 1988.

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Effects of Stand Density on Top Height Estimation for Ponderosa Pine

Western Journal of Applied Forestry ◽

10.1093/wjaf/27.1.18 ◽

2012 ◽

Vol 27 (1) ◽

pp. 18-24 ◽

Cited By ~ 9

Author(s):

Martin Ritchie ◽

Jianwei Zhang ◽

Todd Hamilton

Keyword(s):

Ponderosa Pine ◽

Stand Density ◽

Tree Height ◽

Site Index ◽

Fixed Number ◽

Site Quality ◽

Height Estimation ◽

Growing Stock ◽

Dominant Height ◽

Definition Of

Abstract Site index, estimated as a function of dominant-tree height and age, is often used as an expression of site quality. This expression is assumed to be effectively independent of stand density. Observation of dominant height at two different ponderosa pine levels-of-growing-stock studies revealed that top height stability with respect to stand density depends on the definition of the dominant height. Dominant height estimates calculated from a fixed number of trees per acre (ranging from 10 to 60 of the tallest trees per acre) were less affected by density than those calculated from a proportion (with the cutoff ranging from 95th to the 70th percentile) of the largest trees in the stand.

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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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Complementarity in mixed-species stands of Abies alba and Picea abies varies with climate, site quality and stand density

Forest Ecology and Management ◽

10.1016/j.foreco.2013.04.038 ◽

2013 ◽

Vol 304 ◽

pp. 233-242 ◽

Cited By ~ 89

Author(s):

David I. Forrester ◽

Ulrich Kohnle ◽

Axel T. Albrecht ◽

Jürgen Bauhus

Keyword(s):

Picea Abies ◽

Abies Alba ◽

Stand Density ◽

Site Quality ◽

Mixed Species

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Population density influences assessment and application of site index

Canadian Journal of Forest Research ◽

10.1139/x00-079 ◽

2000 ◽

Vol 30 (9) ◽

pp. 1472-1475 ◽

Cited By ~ 30

Author(s):

David W MacFarlane ◽

Edwin J Green ◽

Harold E Burkhart

Keyword(s):

Loblolly Pine ◽

Geographic Location ◽

Stand Density ◽

Tree Height ◽

Significant Negative Correlation ◽

Site Index ◽

Height Growth ◽

Planting Density ◽

Site Quality ◽

Pinus Taeda L

The height growth of dominant trees in plantations is often assumed to be independent of initial planting density. This assumption allows for the use of dominant tree height as an index of site quality. We found that this assumption was false for the seven tallest trees in 184 even-aged loblolly pine (Pinus taeda L.) stands, planted at nine initial planting densities, at four different geographic locations. A strong, highly significant negative correlation was found between dominant height and initial planting density for stands 14 and 16 years of age. This leads to large differences in predicted site index for stands with different initial planting densities planted at the same geographic location. Use of these site indices to predict yield produced large differences in predicted yield (m3/ha) at age 25. These results provide strong evidence for density-dependent height growth, even for dominant trees in the stand, and suggest that site index, used as a measurement of site quality, is confounded with stand density.

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Reevaluating the self-thinning boundary line for ponderosa pine (Pinus ponderosa) forests

Canadian Journal of Forest Research ◽

10.1139/cjfr-2013-0133 ◽

2013 ◽

Vol 43 (10) ◽

pp. 963-971 ◽

Cited By ~ 24

Author(s):

Jianwei Zhang ◽

William W. Oliver ◽

Robert F. Powers

Keyword(s):

Pinus Ponderosa ◽

Ponderosa Pine ◽

Stochastic Frontier ◽

Site Occupancy ◽

Stand Density ◽

Site Index ◽

The Self ◽

Site Quality ◽

Boundary Line ◽

The Face

The self-thinning rule has been used extensively to predict population dynamics under intraspecific and interspecific competition. In forestry, it is an important silvicultural concept for maintaining stand health in the face of climate change and biotic stress, but uncertainty exists because traditional self-thinning limits were set subjectively without regard to site quality. We addressed this by analyzing ponderosa pine (Pinus ponderosa Lawson & C. Lawson) data from 109 research plots measured repeatedly and 59 inventory plots measured once across California. Self-thinning boundaries were fitted to the data with quantile regression and stochastic frontier function (SFF) techniques with and without site index (SI) as a covariate. The models from both methods fitted the data well with either research plots or all plots. Slopes for size-density trajectories were –0.45 with the 0.99 quantile and –0.47 for SFF. Maximum stand density indices (SDI) were 1250 trees per hectare (TPH) with the 0.99 quantile and 1050–1060 TPH with SFF. Mortality occurred when site occupancy from SFF reached 0.75, suggesting a zone of imminent mortality. Curvilinear trends in maximum SDI across SI for both methods indicate that self-thinning varies with site quality. Any management regimes that increase site quality and productivity will increase the self-thinning boundary.

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Leaf area - sapwood area relations of lodgepole pine as influenced by stand density and site index

Canadian Journal of Forest Research ◽

10.1139/x88-036 ◽

1988 ◽

Vol 18 (2) ◽

pp. 247-250 ◽

Cited By ~ 56

Author(s):

James N. Long ◽

Frederick W. Smith

Keyword(s):

Leaf Area ◽

Forest Ecology ◽

Lodgepole Pine ◽

Stand Density ◽

Site Index ◽

Site Quality ◽

Cross Sectional ◽

Sapwood Area ◽

Pine Trees ◽

Stand Conditions

Leaf area to sapwood area ratios for a given species are believed to vary with factors such as site quality, stand density, early stand growth rates, and crown class. Based on data from 55 mature lodgepole pine trees (Pinuscontorta var. latifolia Dougl.) from 10 plots in southeastern Wyoming, we conclude that putative density and site effects on leaf area - sapwood area relations are actually a consequence of the increase in the leaf area to sapwood area ratio with increasing sapwood area. When leaf area is estimated with a nonlinear model that includes tree size and distance to the live crown, the apparent effects of stand density and site index disappear. We consider a constant ratio of leaf area and sapwood cross-sectional area to be inappropriate for the estimation of leaf area aross the range of stand conditions included in most studies of forest ecology.

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Comparing site quality indices and productivity in ponderosa pine stands of western Montana

Canadian Journal of Forest Research ◽

10.1139/x88-052 ◽

1988 ◽

Vol 18 (3) ◽

pp. 346-352 ◽

Cited By ~ 41

Author(s):

Scott D. McLeod ◽

Steven W. Running

Keyword(s):

Leaf Area Index ◽

Leaf Area ◽

Ponderosa Pine ◽

Volume Growth ◽

Stand Density ◽

Site Index ◽

Site Quality ◽

Area Index ◽

Water Index ◽

Available Water

Four indices of site quality were compared with volume growth of pure, ideal ponderosa pine (Pinusponderosa Laws.) stands in western Montana. Indices based on quantifying the biophysical factors or physiological processes that control productivity (available water index and a relative index of seasonal photosynthesis from computer simulations) worked as well as those based on tree or stand measurements (site index and leaf area index). The following correlations of mean annual stem volume increment were found: with leaf area index, R2 = 0.93; with available water index, R2 = 0.95; with site index, R2 = 0.98; with gross photosynthesis R2 = 0.96. The available water and photosynthesis indices were also highly correlated to site index (R2 > 0.95). However, the tree-dependent site quality indices varied by stand density. Leaf area index and volume growth increased with stand density while site index decreased. Simulations indicated that depletion of soil water effectively halted transpiration and photosynthesis by midsummer and illustrated that even with adequate water, cold spring and fall temperatures ultimately defined the length of the growing season and hence site quality. We conclude that an ecosystem process model can provide an index to site quality independent of tree or stand measurements.

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Relative stocking index: a proposed index of site quality

Canadian Journal of Forest Research ◽

10.1139/x94-173 ◽

1994 ◽

Vol 24 (7) ◽

pp. 1330-1336 ◽

Cited By ~ 5

Author(s):

William E. Berguson ◽

David F. Grigal ◽

Peter C. Bates

Keyword(s):

Surface Soil ◽

Stand Density ◽

Site Index ◽

Site Quality ◽

Site Factors ◽

Forest Inventory And Analysis ◽

Alternative Index ◽

Lake States ◽

Annual Water ◽

Using Data

Site index is difficult to implement and interpret in multispecies, multiple-aged stands, and its relationship to site factors is obscure. Using data from the USDA forest inventory and analysis (FIA) for the Lake States, we developed log-log relationships between mean tree size and stand density for five cover types. Fits were good, with r2 from 0.96 to 0.98 and slopes from −0.948 to −0.995. We define an alternative index of site quality, the relative stocking index (RSI), as the ratio of a stand's measured density to that predicted using the log–log relationship for its cover type (the norm). We divided the range of RSI into three classes for each type (<0.9 of norm, >0.91 but <1.1 of norm, and >1.1 of norm). Based on analyses of the 1977 and 1990 FIA data from Minnesota, class assignments for individual stands remained constant over that 13-year period. Relationships between site factors and either RSI classes or analogous classes based on site index were examined in a subset of 169 stands. Temperature, precipitation, silt content of surface soil, and calculated annual water deficit all differed significantly among RSI classes, but not among site-index classes. The RSI is easy to apply, robust (resistant to change), and related to site factors. It merits additional examination as an index of site quality, especially in heterogenous stands.

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A Direct Measure of Stand Density Based on Stand Growth

Forest Science ◽

10.1093/forsci/fxaa038 ◽

2020 ◽

Author(s):

Thomas J Dean ◽

Anthony W D’Amato ◽

Brian J Palik ◽

Mike A Battaglia ◽

Constance A Harrington

Keyword(s):

Ponderosa Pine ◽

Site Occupancy ◽

Stand Density ◽

Site Quality ◽

Direct Measure ◽

Canopy Architecture ◽

Height Increment ◽

Individual Tree ◽

Growing Stock ◽

Volume Increment

Abstract Standardizing gross volume increment on periodic height increment of the dominant trees is a means of minimizing the effects of site quality and age in growth–growing-stock relations; however, volume increment per height increment contains more information than just a normalization method for fitting growth models. This study builds on previous work suggesting that the cumulative sum of the ratios between individual-tree volume increment and height increment may be a direct measure of stand density. We used data from several levels of growing-stock studies for Douglas-fir, ponderosa pine, and red pine to explore this hypothesis. Regression analysis indicated that the sum of the ratios is proportional to(Dqx⋅N), the underlying equation form of Reineke’s stand density index. Stem growth is a function of canopy dynamics, and additional analyses showed that volume added per unit of height growth was also related to canopy architecture, increasing with decreasing live-crown ratio and increasing foliage density. The linkages between growth, canopy architecture, intermediary canopy dynamics, and (Dqx⋅N) support the hypothesis that the sum of the tree ratios between volume increment and height increment is a direct measure of site occupancy due to its association between growth and corresponding resource use. Study Implications Stand density indices are fundamental to managing the development of forest stands to achieve habitat and production goals, and advanced statistical techniques are providing silviculturists with more precise tools to manage density. However, the increased precision is only available with data from self-thinning stands, rare in managed forests. Furthermore, silviculturists must assume that constant fractions of relative stand density are parallel to fitted self-thinning trajectories. The results of this study show that the slope of the stand density gradient can be determined without data from self-thinning stands and the gradient in stand density runs parallel to the trajectory of self-thinning stands.

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