Eucalyptus globulus Coppices in Portugal: Influence of Site and Percentage of Residues Collected for Energy

Studies that quantify forest bioenergy potentials hardly address the questions of site quality, proportion and type of residues removed from the stands, and environmental impacts of those removals. However, those factors are important for energy-potential results and forest sustainability. This study compares, in terms of residual biomass availability for energy production and of sustainability, different locations, site indices, and forest management strategies in Eucalyptus globulus stands for pulp and paper in northern and central Portugal. A growth and production simulator was used to calculate the availability of residues and the area needed to supply a biomass-fired power plant under a variety of scenarios. Regions with more rainfall generate more residues, but site index and quantity and type of residues harvested are the most important factors. Under the different scenarios analyzed, the amount of residues potentially harvested range from 0.7 to 4.3 Mg ha−1 a−1, the upper bound corresponding to a scenario where stumps are valorized. The maximization of residue removal maximizes the bioenergy produced but has to be considered prudently. Studies indicate that stump removal has limited effect on Eucalyptus globulus stand productivity, diversity, and system sustainability, but impacts of residue removals increase with a decrease in site index.

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A Model to Account for Potential Correlations Between Growth of Loblolly Pine and Changing Ambient Carbon Dioxide Concentrations

Southern Journal of Applied Forestry ◽

10.1093/sjaf/27.4.279 ◽

2003 ◽

Vol 27 (4) ◽

pp. 279-284 ◽

Cited By ~ 2

Author(s):

James A. Westfall ◽

Ralph L. Amateis

Keyword(s):

Carbon Dioxide ◽

Loblolly Pine ◽

Atmospheric Carbon Dioxide ◽

Management Strategies ◽

Co2 Concentration ◽

Site Index ◽

Growth And Yield ◽

Site Quality ◽

Carbon Dioxide Concentrations ◽

Carbon Dioxide Co2

Abstract Continuously increasing concentrations of atmospheric carbon dioxide (CO2) may be leading to enhanced growth rates for loblolly pine. In order to plan effectively silvicultural regimes and harvesting schedules, managers of loblolly pine plantations may wish to account for these potential changes when making growth and yield projections. Data from 94 unthinned plots across the Southeast were used to develop an equation that utilizes change in ambient CO2 concentration and initial site quality to predict change in site index (ΔSI). For a given change in CO2 concentration, a greater increase in site index is afforded to lower quality sites. The ΔSI equation was incorporated into a loblolly pine growth model. Simulations with and without site index adjustments were performed and plot volume estimates were compared to observed values. Mean percent residual dropped from 9.7% with no adjustment to -0.5% when ΔSI was employed. Forest managers can use this model to evaluate how possible CO2-induced growth increases may affect long-term timber yields and management strategies. South. J. Appl. For. 27(4):279–284.

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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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Ponderosa Pine Habitat Types as an Indicator of Site Quality in the Dixie National Forest, Utah

Western Journal of Applied Forestry ◽

10.1093/wjaf/4.2.52 ◽

1989 ◽

Vol 4 (2) ◽

pp. 52-54 ◽

Cited By ~ 2

Author(s):

David L. Verbyla ◽

Richard F. Fisher

Keyword(s):

Pinus Ponderosa ◽

Ponderosa Pine ◽

Tree Species ◽

Habitat Type ◽

Site Index ◽

Site Quality ◽

National Forest ◽

Habitat Types ◽

Quercus Gambelii ◽

Generally True

Abstract Forest habitat types have been purported to be useful indicators of site quality. This is generally true for habitat types with different dominant tree species. However, few have studied the site indicator value of habitat types with the same dominant tree species. We measured site index (base age 25) from 172 randomly selected plots within the ponderosa pine (Pinus ponderosa) zone of the Dixie National Forest, Utah. The range of site index within any one habitat type was broad. Poor sites occurred on all five habitat types. However, the best sites occurred only on the Pinus ponderosa/Symphoricarpos oreophilus and Pinus ponderosa/Quercus gambelii habitat types. Therefore, habitat type may be useful in predicting the best sites, but only if other site information is used in addition to habitat type. West. J. Appl. For. 4(2):52-54, April 1989.

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Yields of Southwestern Pinyon-Juniper Woodlands

Western Journal of Applied Forestry ◽

10.1093/wjaf/3.3.70 ◽

1988 ◽

Vol 3 (3) ◽

pp. 70-74 ◽

Cited By ~ 1

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.

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Suitability of two methods of evaluating site quality for sugar maple in central Ontario

The Forestry Chronicle ◽

10.5558/tfc82733-5 ◽

2006 ◽

Vol 82 (5) ◽

pp. 733-744 ◽

Cited By ~ 2

Author(s):

Nicholas J Buda ◽

Jian R Wang

Keyword(s):

Sugar Maple ◽

Quality Evaluation ◽

Growth Models ◽

Site Index ◽

Height Growth ◽

Site Quality ◽

Dominant Height ◽

Index Site ◽

Species Mixture ◽

Stand Conditions

Stem analyses data collected in central Ontario stands were used to develop site index (height and age) and site form (height and diameter) models and curves for sugar maple. The suitability of both methods for evaluating sugar maple site productivity was examined. Two different equation forms were evaluated for both site index and site form models. A common modification of Richard's (1959) equation was most suitable for predicting dominant height at index age (site index) and reference diameter (site form). Potential effects of species mixture on sugar maple site index were examined. We found no significant effects on sugar maple height growth and site index in mixed stand conditions common in the region when compared to pure stands. The potential of site form as an alternative to site index was investigated through correlation analyses with site index and other site variables known to influence sugar maple height growth. Site form was not related to site index, nor any site variables related to sugar maple height growth. It is therefore inadequate for evaluating sugar maple site quality. We recommend height growth models and site index curves developed in this study be used to replace those from other regions currently used in central Ontario. Key words: site index, site form, sugar maple, site quality evaluation, mixedwood, uneven-aged

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AN EVALUATION OF SEVERAL METHODS OF ESTIMATING SITE INDEX OF IMMATURE STANDS

The Forestry Chronicle ◽

10.5558/tfc28063-3 ◽

1952 ◽

Vol 28 (3) ◽

pp. 63-74 ◽

Cited By ~ 4

Author(s):

John W. Ker

Keyword(s):

Basal Area ◽

Site Index ◽

Site Quality ◽

Average Height ◽

Office Procedure ◽

Minimum Sample ◽

A Site ◽

The University ◽

Site Classes

The use of dominant heights for the estimation of site index is compared with the use of the average of dominant and codominant heights. Data collected on the University Research Forest are presented to illustrate the variability in tree heights and diameters within the two upper crown classes in well-stocked stands of immature Douglas fir.HeightIt is shown that the use of dominant heights reduces considerably the number of measurements required for a site index determination of given accuracy. Minimum sample sizes are given for three limits of accuracy for use in different site qualities. A general field and office procedure is outlined for the determination of minimum sample size in stands other than those described.DiameterThe use of diameter in site determination is discussed. Site indices based on the height of the tree of mean diameter, the height of the tree of mean basal area, and mean height are compared.ConclusionsQuick estimates of site quality can best be obtained by the measurement of total height of sample dominant trees, selected at random. For this purpose, tables are presented which list the average height of dominant trees by age and site classes for use in stands of Douglas fir, and western hemlock, respectively.

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Influences of Forest Type, Stand Age, and Weather on Deer Weights and Antler Size in the Southern Appalachians

Southern Journal of Applied Forestry ◽

10.1093/sjaf/21.1.11 ◽

1997 ◽

Vol 21 (1) ◽

pp. 11-18 ◽

Cited By ~ 4

Author(s):

William M. Ford ◽

A. Sydney Johnson ◽

Philip E. Hale ◽

James M. Wentworth

Keyword(s):

Age Structure ◽

Forest Type ◽

Site Index ◽

Forest Stand ◽

Site Quality ◽

Stand Age ◽

Southern Appalachians ◽

Study Region ◽

Pinus Spp ◽

Percent Area

Abstract We analyzed correlations of forest type, age structure, and site index data with weights and antler characteristics of yearling white-tailed deer (Odocoileus virginianus) bucks from specific localities in the Chattahoochee, Cherokee, Nantahala, and Pisgah national forests in Georgia, Tennessee, and North Carolina. Areas in the northern part of the study region produced larger deer with larger antlers than those in the southern portion of the region. These northern areas differed from those to the south in having more diverse ownership and land use and in origins of deer stock. Weights and antler characteristics were significantly correlated (P < 0.05) with percent area in the cove hardwood type, but otherwise were poorly correlated with forest stand type and site index. Percent area in young (0-8 yr old) cove hardwood and in mid-successional (9-20 and 21-40) cove hardwood, pine (Pinus spp.), and upland oak (Quercus spp.) were significantly correlated (P < 0.05) with deer variables, particularly in years following a poor mast crop. Much of the quantifiable habitat influences on deer in the Southern Appalachians probably is masked by low deer densities and the small site quality differences among areas examined. Because much of the forest consists of mature mast-producing oaks and abundant forage is produced in both mature and younger aged stands, deer numbers seem to be below any threshold of quantifiable effects due to forest stand age structure. South. J. Appl. For. 21(1):11-18.

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Growth Intercept Methods for Predicting Site Index in White Pine Plantations in the Glaciated Areas of Ohio

Northern Journal of Applied Forestry ◽

10.1093/njaf/23.3.176 ◽

2006 ◽

Vol 23 (3) ◽

pp. 176-183 ◽

Cited By ~ 1

Author(s):

James H. Brown

Keyword(s):

Site Index ◽

Growth Increment ◽

Annual Growth ◽

Site Quality ◽

Soil Horizon ◽

Regression Equations ◽

White Pine ◽

Annual Increment ◽

Growth Intercept ◽

Annual Growth Increment

Abstract Growth intercept (GI) techniques were evaluated for estimating site quality in white pine stands planted on old-field sites in the Wisconsin-aged glaciated areas of northern and western Ohio. Correlations between growth of trees below the breast high (bh) annual growth increment andheight growth from bh and above were not statistically significant. Site index estimates were made using age at bh and height from the bh annual growth increment to the growing tip. Three-year and 5-year growth beginning 3 years above the bh annual increment and 10-year growth beginning oneinternode above bh were significantly more correlated with height than were intercepts beginning at bh. In multiple regression equations developed for predicting site index, 3-, 5- and 10-year intercepts, along with age at bh, accounted for 76, 77, and 80%, respectively, of the variationin tree heights and 35-year site indices varied from 60 to 83 ft. Combining clay content of the B2 soil horizon with GI and age increased the variation accounted for by 3-, 5-, and 10-year GI equations to 79, 78, and 81%, respectively, and the improvement in site index estimatesover those using GIs alone was not more than ±2 ft within any given GI measurement.

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STUDIES IN FOREST PATHOLOGY: XII. DECAY OF WESTERN HEMLOCK IN THE UPPER COLUMBIA REGION, BRITISH COLUMBIA

Canadian Journal of Botany ◽

10.1139/b54-014 ◽

1954 ◽

Vol 32 (1) ◽

pp. 145-171 ◽

Cited By ~ 4

Author(s):

R. E. Foster ◽

H. M. Craig ◽

G. W. Wallis

Keyword(s):

Site Index ◽

Tsuga Heterophylla ◽

Western Hemlock ◽

Site Quality ◽

Advanced Stage ◽

Multiple Correlation ◽

Relative Percentage ◽

Total Incidence ◽

Average Defect ◽

Mature Stands

An investigation of western hemlock (Tsuga heterophylla (Raf.) Sarg.) in the Upper Columbia region has shown that decay losses are excessive, amounting to 52 and 74% in terms of cubic and board foot computations respectively. The logs of 833 hemlock on 36 sample plots located in mature timber were analyzed in detail. Twenty-six decay-producing fungi have been isolated. Sixty-two per cent of the total decay was attributed to Echinodontium tinctorium Ell. & Ever. and 25% to Fomes pini (Thore) Lloyd. Considerable variation in the fungi responsible for decay was encountered intraregionally. Stand defect losses varied from 38 to 71%. Some of this variation could be predicted on the basis of the site index determinations of hemlock. Relative to the total incidence and importance of decay, Echinodontium tinctorium decreased and Fomes pini increased in significance with increasing site quality. Sporophores, scars, dead tops, large rotten branches, swollen knots, frost cracks, forked trees, and trunk infections of mistletoe were classed as indicators of significance in relation to hidden defect. Living trees, classed as Suspect or Residual depending on the presence or absence of one or more reliable indicators of defect, were found to differ appreciably in average defect. Within each of the preceding classes decay increased progressively with increasing diameter and decreasing site quality. Immature hemlock was found to be susceptible to appreciable decay and mature stands reached an advanced stage of deterioration at 250 years. Multiple correlation analyses between percentage of decay, site, age, and the relative percentage of Residual trees weighted by volume permitted an estimate of total stand defect within ± 7%.

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SITE QUALITY ESTIMATIONS BASED ON THE GENERALIZED ALGEBRAIC DIFFERENCE APPROACH: A CASE STUDY IN ÇANKIRI FORESTS

Revista Árvore ◽

10.1590/1806-90882018000300011 ◽

2018 ◽

Vol 42 (3) ◽

Author(s):

Ugur Akbas ◽

Muammer SENYURT

Keyword(s):

Site Index ◽

Site Quality ◽

Model Parameters ◽

Successful Model ◽

Index Model ◽

Prediction Technique ◽

Algebraic Difference ◽

Pine Stands ◽

Site Index Model ◽

Generalized Algebraic Difference Approach

ABSTRACT In this study, it is aimed that the dynamic site index models were developed for Crimean Pine stands in Sarikaya-Cankiri forests located in middle northern Turkey. The data for this study are 153 sample trees obtained from the Crimean Pine stands. In modeling relationships between height and age of dominant or co-dominant trees, some dynamic site index equations such as Chapman-Richards (M1, M2, M3), Lundqvist (M4 and M6), Hossfeld (M5), Weibull (M7) and Schumacher (M8) based on the Generalized Algebraic Difference Approach (GADA) were used. The estimations for these eight-dynamic site index model parameters with well as various statistical values were obtained using the nonlinear regression technique. Among these equations, the Chapman-Richards’s equation, M3, was determined to be the most successful model, with accounted for 89.03 % of the total variance in height-age relationships with MSE: 1.7633, RMSE: 1.3279, SSE: 1165.6, Bias: -0.0380. After determination of the best predictive model, ARMA (1, 1) autoregressive prediction technique was used to account autocorrelation problems for time-series height measurements. When ARMA autoregressive prediction technique was applied to the Chapman-Richards function for solving autocorrelation problem, these success statistics were improved as SSE: 868.7, MSE: 1.3183, RMSE: 1.1482, Bias: -0.06369, R2: 0.918. Also, Durbin-Watson statistics displayed that autocorrelation problem was solved by the use of ARMA autoregressive prediction technique; DW test value=1.99, DW<P=0.5622, DW>P=0.4378. The dynamic site index model that was developed has provided results compatible with the growth characteristics expected in the modeling of height-age relations, such as polymorphism, multiple asymptote, and base-age invariance.

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