scholarly journals A Direct Measure of Stand Density Based on Stand Growth

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.

Toward developing a direct relation between gross volume increment and stand density

2013 ◽  
Vol 43 (9) ◽  
pp. 852-860 ◽  
Author(s):  
Thomas J. Dean ◽  
Scott D. Roberts ◽  
Robert S. Seymour
Keyword(s):  
Loblolly Pine ◽  
Stand Density ◽  
Height Increment ◽  
Individual Tree ◽  
Red Alder ◽  
Quadratic Mean ◽  
Stem Size ◽  
Mean Diameter ◽  
Volume Increment ◽  
Quadratic Mean Diameter

A general form for expressing gross volume increment in terms of stand density is derived and tested with data from spacing trials in red alder (Alnus rubra Bong.), eastern white pine (Pinus strobus L.), longleaf pine (Pinus palustris Mill.), and loblolly pine (Pinus taeda L.). The equation relates the stand sum of individual-tree volume increment per metre height increment to a power function of quadratic mean diameter times tree density. The proposed equation fit the data best when the model included an intercept. Within each species, the fits were unbiased with respect to the independent variables, plantation age, and site height, and with the exception of the youngest ages for red alder and loblolly pine, they were unbiased with respect to the plot sums of individual-tree volume increment divided by individual height increment. Exponents estimated for quadratic mean diameter for each species ranged from 1.58 to 1.80. The resulting equations indicate a linear relationship between the stand sum of individual-tree volume increment per metre height increment and stand density. Scattergrams of gross-volume increment per hectare per year and stand density can be recovered by multiplying the predicted values of the regressions by Lorey’s height. The regressions support the hypothesis that each metre of height growth produces consistent changes in stem size, regardless of initial tree size, age, or site quality, and implies that the change in stem size is a predictable power function of stem diameter for an individual tree or quadratic mean diameter for a stand.

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

2013 ◽  
Vol 43 (10) ◽  
pp. 963-971 ◽  
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.

scholarly journals Effects of Stand Density on Top Height Estimation for Ponderosa Pine

2012 ◽  
Vol 27 (1) ◽  
pp. 18-24 ◽  
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.

Yields of Southwestern Pinyon-Juniper Woodlands

1988 ◽  
Vol 3 (3) ◽  
pp. 70-74 ◽  
Author(s):  
Frederick W. Smith ◽  
Thomas Schuler
Keyword(s):  
Maximum Yield ◽  
Stand Density ◽  
Site Index ◽  
Average Density ◽  
Pinus Edulis ◽  
Site Quality ◽  
Mixed Species ◽  
Growing Stock ◽  
Highly Correlated ◽  
Utah Juniper

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.

scholarly journals Lowering Stand Density Enhances Resiliency of Ponderosa Pine Forests to Disturbances and Climate Change

2019 ◽  
Vol 65 (4) ◽  
pp. 496-507 ◽  
Author(s):  
Jianwei Zhang ◽  
Kaelyn A Finley ◽  
Nels G Johnson ◽  
Martin W Ritchie
Keyword(s):  
Climate Change ◽  
Tree Growth ◽  
Ponderosa Pine ◽  
Tree Mortality ◽  
Ring Width ◽  
Basal Area ◽  
Stand Density ◽  
Site Quality ◽  
Climate Trends ◽  
Ponderosa Pine Forests

AbstractStand density affects not only structure and growth, but also the health of forests and, subsequently, the functions of forest ecosystems. Here, we integrated dendrochronology and repeated inventories for ponderosa pine research plots to determine whether long-term growth and mortality responded to climate trends and how varying stand density influenced the responses. The plots were established prior to 1975 on existing stands throughout northern California. Although annual temperature increased consistently for the last 65 years, ring-width indices produced by eliminating age and thinning effects failed to detect radial trend regardless of site quality. However, interannual variation for the indices was substantial, reflecting a strong influence of climate on tree growth. Plot-level basal area increments were significantly affected by tree mortality. Stand density index explained most variation of mortality. Lowering stand density enhanced remaining tree growth, reduced mortality, and increased stand resiliency to disturbances and climate change. Besides higher climate moisture indices or lower vapor pressure deficits, any treatments that improve tree vigor and reduce stress will have a similar effect to reducing stand density. Although neither biotic disturbances nor abiotic conditions can be controlled, forest managers can manage stand density appropriately to enhance resilience to climate change and disturbances.

scholarly journals Precommercial Thinning in a Ponderosa Pine Stand Affected by Armillaria Root Disease in Central Oregon: 30 Years of Growth and Mortality

1999 ◽  
Vol 14 (3) ◽  
pp. 144-148 ◽  
Author(s):  
Gregory M. Filip ◽  
Stephen A. Fitzgerald ◽  
Lisa M. Ganio
Keyword(s):  
Ponderosa Pine ◽  
Tree Mortality ◽  
Basal Area ◽  
Stand Density ◽  
Root Disease ◽  
Diameter Growth ◽  
Individual Tree ◽  
Precommercial Thinning ◽  
Tree Diameter ◽  
Armillaria Root Disease

Abstract A 30-yr-old stand of ponderosa pine was precommercially thinned in 1966 to determine the effects of thinning on tree growth and mortality caused by Armillaria root disease in central Oregon. After 30 yr, crop tree mortality was significantly (P = 0.02) less in thinned plots than in unthinned plots. Tree diameter growth was not significantly (P = 0.17) increased by thinning. Crop-tree basal area/ac growth was significantly (P = 0.03) greater in thinned plots. Apparently, from a root disease perspective, precommercial thinning of pure ponderosa stands significantly decreases the incidence of crop-tree mortality after 30 yr and significantly increases basal area/ac growth but not individual tree diameter growth. Recommendations for thinning based on stand density index (SDI) are given. West. J. Appl. For. 14(3):144-148.

Estimating site productivity in irregular stand structures by indexing the basal area or volume increment of the dominant species

2014 ◽  
Vol 44 (1) ◽  
pp. 92-100 ◽  
Author(s):  
John-Pascal Berrill ◽  
Kevin L. O’Hara
Keyword(s):  
Basal Area ◽  
Stand Density ◽  
Site Productivity ◽  
Mixed Stands ◽  
Individual Tree ◽  
Coast Redwood ◽  
Stand Growth ◽  
Permanent Sample Plots ◽  
Partial Harvesting ◽  
Volume Increment

Estimating site productivity in irregular structures is complicated by variations in stand density, structure, composition in mixed stands, and suppression experienced by subordinate trees. Our objective was to develop an alternate to site index (SI) and demonstrate its application in models of individual-tree and stand growth. We analyzed coast redwood (Sequoia sempervirens (Lamb. ex D. Don) Endl.) tree and stand growth in a grid of 234 permanent sample plots covering a 110 ha study area in north coastal California. Partial harvesting created a mosaic of densities and openings throughout the 60-year-old redwood-dominated forest. Redwood SI was a poor predictor of volume increment (VI) per hectare among redwood in each plot over two decades after harvest. A new index of redwood basal area increment (BAI) productivity, calculated using inventory data for all stems in even-aged stands and the oldest cohort of multiaged stands, was a stronger predictor of VI. Diameter increment of individual redwood trees correlated strongly with stand density and the new BAI index. Forest managers should expect widely divergent responses following partial harvesting in crowded even-aged stands, with the greatest response coming from dominant redwoods with long crowns retained in areas with low residual stand density and high BAI index.

scholarly journals Assessment of Ponderosa Pine Vigor Using Four-Band Aerial Imagery in South Central Oregon: Crown Objects to Landscapes

Forests ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 612
Author(s):  
Charlie Schrader-Patton ◽  
Nancy Grulke ◽  
Craig Bienz
Keyword(s):  
Ponderosa Pine ◽  
Forest Health ◽  
Stand Density ◽  
Aerial Imagery ◽  
Individual Tree ◽  
South Central ◽  
Western Us ◽  
Moderate Drought ◽  
Wildfire Suppression ◽  
Gis Software

Ponderosa pine is an integral part of the forested landscape in the western US; it is the dominant tree species on landscapes that provide critical ecosystem services. Moderate drought tolerance allows it to occupy the transition zone between forests, open woodlands, and grasslands. Increases in stand density resulting from wildfire suppression, combined with lengthening, intensifying, and more frequent droughts have resulted in reduced tree vigor and stand health in dry ponderosa pine throughout its range. To address a management need for efficient landscape-level surveys of forest health, we used Random Forests to develop an object-oriented classification of individual tree crowns (ITCs) into vigor classes using existing, agency-acquired four-band aerial imagery. Classes of tree vigor were based on quantitative physiological and morphological attributes established in a previous study. We applied our model across a landscape dominated by ponderosa pine with a variety of forest treatments to assess their impacts on tree vigor and stand health. We found that stands that were both thinned and burned had the lowest proportion of low-vigor ITCs, and that stands treated before the 2014–2016 drought had lower proportions of low-vigor ITCs than stands treated more recently (2016). Upland stands had significantly higher proportions of low-vigor trees than lowland stands. Maps identifying the low-vigor ITCs would assist managers in identifying priority stands for treatment and marking trees for harvest or retention. These maps can be created using already available imagery and GIS software.

Stand density index in uneven-aged ponderosa pine stands

2003 ◽  
Vol 33 (1) ◽  
pp. 96-100 ◽  
Author(s):  
C W Woodall ◽  
C E Fiedler ◽  
K S Milner
Keyword(s):  
Relative Density ◽  
Ponderosa Pine ◽  
Site Occupancy ◽  
Stand Density ◽  
Summation Method ◽  
Diameter Class ◽  
Density Index ◽  
Pine Stands ◽  
Stand Density Index ◽  
Diameter Distributions

Stand density index (SDI) was developed to quantify relative stand density in even-aged stands. Application of SDI in uneven-aged stands has been described mathematically but not justified biologically. Diameter-class trends in SDI and sapwood area across 14 uneven-aged ponderosa pine (Pinus ponderosa Dougl. ex P. & C. Laws.) stands in eastern Montana were examined to elucidate the biological underpinnings of the SDI summation method. Results indicate that the SDI summation method is biased in its apportionment of relative stand density across diameter classes in uneven-aged ponderosa pine stands. SDI apportions greater relative density to small trees than to larger ones. Therefore, SDI may overpredict site occupancy for reverse J-shaped diameter distributions with more small trees than large ones, and it may underpredict occupancy with nonreverse J-shaped diameter distributions. Application of the SDI summation method in uneven-aged ponderosa pine stands may be biologically justified only if site occupancy – diameter-class trends are taken into account when interpreting SDI values. Replacing the self-thinning scaling factor of the SDI summation method with more biologically relevant scaling relationships may create improved relative density measures for uneven-aged stands.

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