Producing softwood of different quality: does this provide risk compensation?

This study analysed whether the production of high-quality assortments, saw timber and pulpwood in Norway spruce (Picea abies) and Scots pine (Pinus sylvestris) stands leads to effects of risk compensation. Mixtures of conventionally treated pruned and non-pruned stands, as well as mixtures of stands which had been optimized concerning the occurrence of assortments and financial criteria were considered. The price simulation was done by bootstrapping to avoid the assumption of a certain distribution of timber prices, and to preserve the correlations of the timber prices from different assortments. The financial valuation was carried out with annuities within a Monte Carlo simulation with 10,000 repetitions. To quantify the effect of natural hazards, the calculations were repeated with and without this factor. Minimum risk portfolios were determined and optimization performed using both a utility function as well as the value-at-risk approach. The mixtures with minimum risk were dominated by pine stands, as they are less affected by natural hazards and prices for pine timber have a lower volatility, although pine timber prices are generally lower compared to that of spruce timber. These pine dominated portfolios showed risk reductions up to 92% compared to the riskiest single stand, but the annuities were reduced even more. In contrast to this, the portfolios optimized with the utility function and the value-at-risk approach consisted of spruce stands. These spruce portfolios showed an efficient risk reduction of up to 60%. Additionally, higher annuities and larger diversification effects occurred in the portfolios containing the optimized stands. Integrating the risk of natural hazards, the annuities decreased, as did the correlation of the annuities of the different stands, while risk increased. Altogether these effects led to higher relative risk reductions when forming optimal portfolios. These results indicate that producing different assortments of spruce and pine leads to risk compensation, especially when considering portfolios consisting of optimized stands.     

Schnittholzqualität und Furniereignung von Douglasien aus linksrheinischen Anbaugebieten

Summary Douglas fir sample trees from 9 various stands were cut in sawmills. Every board of the converted timber was graded; all defects in timber were analysed, especially all black and sound knots on the surface of the boards were measured. The percentage of good boards prooved to be comparatively low. From fertile sites the sawn timber quality seems to be inferior compared with wood from poorer and dryer sites. Douglas firs grown single between broadleaved stands showed the lowest timber quality. Throughout the quantity and thickness of black knots were responsible for poor quality. Experiments with production of veneer yielded useful carved veneers when sliced of quartered and clear logs. Branchless logs from 80 years old Douglas firs could be worked up to carved veneers, but are too young for peeled veneers. For full veneer logs diameters of 70 cm and structure of small annual rings is essential. For saw timber as well as for veneerwood production short rotation below 120 years is not suitable. Moreover pruning is necessary.      

Mixed forests and a flexible harvest policy: a problem for conventional risk analysis?

The famous “Faustmann” equation, which allows for identifying the most profitable tree species on a given unstocked piece of land, assumes constant timber prices. In reality, timber prices may fluctuate dramatically. Several authors have proven for monocultures that waiting for an acceptable timber price (reservation price) before harvesting (flexible harvest policy) increases the net present value of forest management. The first part of this paper investigates how efficient a flexible harvest strategy may be applied in mixed forests and whether the optimal species mixture is changed under such harvest policy. Mixtures of the conifer Norway spruce [Picea abies (L.) Karst] and the broadleaf European beech (Fagus sylvatica L.) were investigated. In order to evaluate mixed forests, the risks and the correlation of risks between tree species as well as the attitude towards risk of the decision-maker (risk-aversion is assumed) were considered according to the classical theory of optimal portfolio selection. In the second part we took up a recent critique on modern financial theory by Mandelbrot. Whether or not the assumption of normally distributed financial flows, which are supposed to occur under risk, would be appropriate to evaluate the risk of forest management was investigated. Market and hazard risks as well as their correlation were integrated in the evaluation of mixed forests by means of Monte-Carlo simulations (MCS). The risk of the timber price fluctuation was combined with the natural hazard risk, caused mainly by insects, snow and wind. Applying the μ-σ-rule, the mean net present value (NPV) from 1,000 simulations and their standard deviation were used for the optimisation. Given a low-return, risk-free interest rate to assess potential species mixtures of the Norway spruce and European beech, optimal proportions of European beech increased according to the theory of optimum portfolio selection with growing risk aversion from 0 (ignorance of risk) to 60% (great risk-aversion). In relation to a fixed harvest policy, the net present value of both, Norway spruce and European beech, could be increased significantly. Since the hazard risks of European beech were substantially lower compared with the Norway spruce (relation of susceptibility 1:4) beech benefited more from the flexible harvest policy. A comparison of simulated frequency distributions of the NPV with the expected density functions under the assumption of a normal distribution revealed significant differences. Only in the case of European beech was the general shape of the simulated frequency distribution similar to a normal distribution (bell-shaped curve). However, the density of NPV close to the mean was much greater than expected under the assumption of a normal distribution. Consequently, the frequency of a negative NPV for a European beech forest was greatly overestimated when applying the normal distribution. Though the shape of the simulated frequency distribution was rather different from a normal distribution for Norway spruce the simulated part of negative NPV was quite well approximated by the normal distribution. Therefore the simulated and expected frequencies of negative NPV were similar in case of Norway spruce; only a slight underestimation was seen in the assumption of a normal distribution. It can be concluded that actually simulated frequencies of negative NPV seem to be better measures for risk than computed probabilities of negative NPV, which assume normal distribution. As the risk for European beech was greatly overestimated by the conventional assumption of a normal distribution, the optimal proportions of European beech were surely rather underestimated according to the theory of portfolio. MCS on optimum mixtures derived by the classical portfolio theory seems necessary to test the robustness of such mixtures.

Effects of root trenching of overstorey Norway spruce (Piceaabies) on growth and biomass of underplanted beech (Fagussylvatica) and Douglas fir (Pseudotsugamenziesii) saplings

In Central Europe, the conversion of pure Norway spruce stands (Picea abies [L.] Karst.) into mixed stands with beech (Fagus silvatica L.) and other species like e.g. Douglas fir (Pseudotsuga menziesii [Mirb.] Franco) is accomplished mainly by underplanting of seedlings beneath the canopy of overstorey spruce trees after partial cutting treatments what means exposure to shade and below-ground root competition by the overstorey to the seedlings. Particularly about the second factor, our knowledge is limited. Therefore, we carried out a below-ground competition exclusion experiment by root trenching and investigated the effects on soil resources, growth, and biomass partitioning of underplanted beech and Douglas fir saplings under target diameter and strip cutting treatments. The exclusion of overstorey root competition by trenching increased the soil water potential in the second year that had a fairly dry growing season and led to significantly higher foliar concentrations of most nutrients, particularly in Douglas fir, indicating an amended nutrient supply. Both improvements were accompanied by an increase in length and diameter increment of the underplanted saplings, appearing in both species only after having surpassed a species-specific threshold light value (Douglas fir 16% of above canopy radiation, beech 22%). We also found significant interactions between trenching and light for specific fine root length and further biomass and morphological parameters. Judged by the much steeper increase in height and diameter growth with increasing light after release from below-ground competition, Douglas fir saplings appeared to be more sensitive to root competition than beech saplings what conforms to older findings for beech. According to our results, a strip cutting seems to be more appropriate than a target diameter cutting treatment to replace a pure spruce stand by a mixed stand with beech and Douglas fir.     

Product diversification in South Africa’s commercial timber plantations: a way to mitigate investment risk

We used the portfolio method to examine how a forest company can lower investment risk by producing a mix of timber products. We derived optimum combinations of pine (Pinus patula) saw timber production and eucalypt (Eucalyptus grandis) pulpwood production at landscape level. Our results indicate that producing a product mix rather than a single product improves aggregated financial returns and lowers investment risk over multiple rotation periods. The optimum mixture depended on past timber price correlations for pulpwood and sawn timber in South Africa between 1980 and 2011. This ideal mixture is comprised of areal ratios of about 45% saw timber and 55% pulpwood. Our example shows how economic risk of a forest investment can be reduced by creating a portfolio of a number of products. The risk that an investor has to accept for each monetary unit that is expected in return can be reduced by over 40% when comparing the risk–return combinations of a pure pine saw-timber stand with that of a portfolio of forest products. The risk associated with the production can be reduced by 20% when growing a portfolio of products rather than eucalypt pulpwood only.     

Larval performances and life cycle completion of the Siberian moth, <Emphasis Type="Italic">Dendrolimus sibiricus</Emphasis> (Lepidoptera: Lasiocampidae), on potential host plants in Europe: a laboratory study on potted trees

The Siberian moth, Dendrolimus sibiricus, Tschtv. is the most harmful defoliator of coniferous forests in North Asia. The pest has already spread over the Urals and continues moving westwards. Recently, it has been recommended for quarantine in member countries by European and Mediterranean Plant Protection Organization (EPPO). The performances of the pest on coniferous species planted in Europe were assessed on a range of potted trees corresponding to the spectrum of economically important conifers in the EU: European larch Larix decidua, Norway spruce Picea abies, Scots pine Pinus sylvestris, European black pine Pinus nigra, and the North American species: Douglas fir Pseudotsuga menziesii and grand fir Abies grandis. Larvae showed a potential to survive and complete the development on all these host tree species. Favorable hosts were grand fir, European larch, and Douglas fir that allowed higher survival, better larval development, and as a result, yielded heavier pupae and adult moths with higher longevity. Black pine was a poor host but, however, could still support larval and pupal development. Norway spruce and Scots pine had an intermediate behavior. If accidentally introduced to Europe, the Siberian moth may become especially damaging in forest stands predominated by European larch and by the North American firs. Norway spruce and especially the two-needle pines will be less prone to intensive defoliation by this species. The fact that the pest may damage the range of economically important coniferous species should be taken into account in the pest risk assessment for Europe and also for North America where the Siberian moth occurrence is considered likely.     

Comparison of nearest neighbour approaches for small area estimation of tree species-specific forest inventory attributes in central Europe using airborne laser scanner data

The three nonparametric k nearest neighbour (kNN) approaches, most similar neighbour inference (MSN), random forests (RF) and random forests based on conditional inference trees (CF) were compared for spatial predictions of standing timber volume with respect to tree species compositions and for predictions of stem number distributions over diameter classes. Various metrics derived from airborne laser scanning (ALS) data and the characteristics of tree species composition obtained from coarse stand level ground surveys were applied as auxiliary variables. Due to the results of iterative variable selections, only the ALS data proved to be a relevant predictor variable set. The three applied NN approaches were tested in terms of bias and root mean squared difference (RMSD) at the plot level and standard errors at the stand level. Spatial correlations were considered in the statistical models. While CF and MSN performed almost similarly well, large biases were observed for RF. The obtained results suggest that biases in the RF predictions were caused by inherent problems of the RF approach. Maps for Norway spruce and European beech timber volume were exemplarily created. The RMSD values of CF at the plot level for total volume and the species-specific volumes for European beech, Norway spruce, European silver fir and Douglas fir were 32.8, 80.5, 99.0, 137.0 and 261.1%. These RMSD values were smaller than the standard deviation, although Douglas fir volume did not belong to the actual response variables. All three non-parametric approaches were also capable of predicting diameter distributions. The standard errors of the nearest neighbour predictions on the stand level were generally smaller than the standard error of the sample plot inventory. In addition, the employed model-based approach allowed kNN predictions of means and standard errors for stands without sample plots.     

丝栗栲林生长与生产力的研究

在福建省邵武市洪墩采育场，调查丝栗栲林标地１０块，做平均木、树干解析木９株，杉木人工林标地２块，研究丝栗栲的生长与生产力，结果表明：丝栗栲林的胸径、树高及单株材积总生长量，均随年龄的增加而增加；胸径２０ａ前生长最快；树高１６ａ前生长最快；材积３６ａ时尚未有下降的趋势。胸径、树高平均生长量，随年龄增加而增加，当生长量达高峰后，则随年龄的增加而下降；胸径生长高峰，好立地１２ａ，中、劣立地１５ａ；树高生长高峰，好立地１０ａ，中立地８ａ，劣立地１２ａ；材积平均生长量，随年龄增加而增加，好、劣立地３６ａ时仍未下降，中立地３４ａ时生长量最大。胸径、树高连年生长量随年龄增加而下降；材积连年生长量，随年龄增加而增加，当生长量达高峰后，则随年龄增加而下降，生长高峰出现的年龄，好立地２８ａ，中立地２２ａ，劣立地２６ａ。在相似的立地条件下，丝栗栲林的蓄积量比杉木人工林低，但乔木层总生物量比杉木林高。     

Mortality and growth of dwarf mistletoe‐infected red and white fir and the efficacy of thinning for reducing associated losses

In managed forests dominated by true fir (Abies) species, stands are often restocked using understory trees retained during timber harvest, making the effects of dwarf mistletoe (Arceuthobium spp.) infestation on small true fir a concern. This study examined the response of small red (A. magnifica) and white (A. concolor) fir and their dwarf mistletoes (A. abietinum f.sp. magnificae and A. abietinum f.sp. concoloris, respectively) to precommercial thinning treatments in fir‐dominated stands in the Sierra Nevada Mountains of California. Tree diameters and dwarf mistletoe ratings were monitored from 1981 to 2001, and mortality was observed from 1981 to 2006. Red and white fir survival and radial growth decreased significantly with greater mistletoe ratings and increased with larger diameters and live crown ratios. Thinning significantly increased survival and growth of white, but not red fir. Over the course of the study, mistletoe ratings for both fir species did not change significantly in unthinned stands, but increased in thinned stands. However, while statistically significant, increases in mistletoe ratings in thinned stands were gradual and mistletoe ratings did not statistically differ between treatments 20 years post‐thinning. Additionally, thinning did not significantly influence mistletoe spread to uninfected trees, indicating that precommercial thinning in lightly infested red and white fir stands will not likely result in substantial increases in dwarf mistletoe abundance over typical harvesting intervals. Overall, while severe dwarf mistletoe infection ratings reduced tree survival and growth, because ratings remained low, actual losses resulting from mistletoes during this study were minor and will not likely result in substantial economic losses over normal harvesting intervals. This finding indicates that precommercial thinning treatments designed specifically to compensate for mistletoe‐associated losses may not be necessary when managing red and white fir for timber production.     

Regeneration and structure of mixed conifer forests under single-tree harvest management in the western Bhutan Himalayas

We examined the regeneration and structure of mixed conifer forests under single-tree harvest management in western Bhutan. Sixteen 900 m² (30 m × 30 m) plots were sampled at four Forest Management Units (FMUs; Chamgang, Gidakom, Paro-Zonglela, and Haa-East) representing the forest type, including half the plots in single-tree harvest stands and half in unlogged stands. In addition, we solicited information on traditional forest management practices from informants using survey questionnaires and collected tree species data from felling records from respective local forest offices. Rural timber demand is concentrated on the removal of straight and well-formed bluepine trees for beams, planks, and scaffolding. Single-tree harvest, however, has not significantly altered stand structures from unlogged stands. Similarly, tree regeneration is not different when comparing single-tree harvest and unlogged stands, except at Chamgang FMU, where seedling densities were generally higher in harvested stands than in unlogged stands. These results indicate that single-tree harvest is not detrimental to regeneration and utilization of mixed conifer forests in western Bhutan.     

Growth reduction in harvest-age,coniferous forests with residual trees in the western central Cascade Range of Oregon

To evaluate the relationship of overstory residual trees to the growth of unmanaged young-to-mature understory Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) and western hemlock (Tsuga heterophylla (Raf.) Sarg.), the basal area and volume of 14 paired plots with and without residual trees were examined in the Willamette National Forest, Oregon. Residual trees were large survivors of the fires that initiated the understory between 55 and 121 yr ago. Understory stands were naturally regenerated and not managed in any way. High residual tree and understory densities were negatively associated with understory volume. The relation of density of residual trees to total understory and Douglas-fir basal areas and volumes was best described by a negative logarithmic function. The rate of decrease in total understory and Douglas-fir basal areas and volumes per individual residual tree became smaller with increasing residual-tree density. Predicted total understory volume reduction was 23% with five residual trees/ha and 47% with 50 residual trees/ha, averaging 4.6% and 0.9% per residual tree, respectively. After including the estimated volume growth of residual trees since initiation of the understory, stand volume was still 19% lower with five residual trees/ha and 41% lower with 50 residual trees/ha than in stands with no residual trees, averaging a reduction of 38% and 0.8% per residual tree, respectively. In mixed stands of Douglas fir and western hemlock, predicted Douglas-fir basal area and volume declined more rapidly than did total understory basal area and volume when residual-tree densities exceeded about 15 trees/ha. This difference was probably due to the relative shade-intolerance of Douglas fir. Predicted Douglas-fir volume reduction was 13% with five residual trees/ha and 75% with 50 residual trees/ha, averaging 2.6% and 1.5% per residual tree, respectively. The southern aspects had more than 150% the total understory basal area and volume and more than 200% the Douglas-fir volume and basal area of the northern aspects. Lower density and basal area of understory trees, particularly of dominant and codominant Douglas fir, were associated with increasing residual-tree densities. Given the same diameter at breast height (DBH), heights of Douglas fir were not related to residual trees. Regardless of understory age, understory volume was greatest in stands with the lowest understory densities. These results suggest that timber production in unthinned green-tree retention units may be reduced and may depend on the density of leave-trees. Thinning of understory trees is recommended to reduce growth loss from intraspecific competition.     

The pine pathogen Diplodia sapinea is associated with the death of large Douglas fir trees

Climate change poses severe pressures to European conifer forests. Using non-native tree species, such as Douglas fir (Pseudotsuga menziesii), is one proposed strategy to circumvent adverse effects for forest management. However, novel forest health risks can impair the cultivation of non-native trees. In 2022, we observed large Douglas fir trees (approximately 40–50 years old, diameter at breast height (dbh) 21–41 cm) that had recently died in spring or summer 2022 in three forest stands in Eastern Austria. Intensive resin flow, blue-staining of the sapwood and the absence of bark- and wood-boring insects indicated a fungal infection. Isolations from blue-stained sapwood of the dead trees consistently yielded cultures of the opportunistic pathogen Diplodia sapinea. In a greenhouse wound inoculation experiment, seven D. sapinea isolates obtained from Douglas fir caused phloem necrosis, blue-staining of sapwood and mortality and thus displayed pathogenicity towards seedlings of both Ps. menziesii and its common host, Scots pine (Pinus sylvestris). Diplodia sapinea produced significantly longer areas of blue-stain as well as higher and faster mortality in Ps. menziesii compared to P. sylvestris. We conclude that D. sapinea substantially contributed to the death of seven of the 13 examined large Douglas fir trees. While this fungus has been described as a pathogen of young Douglas fir trees before, this is the first report that it can potentially kill large individuals of this conifer species under drought conditions. Thus, our results indicate that D. sapinea could represent a severe threat to the cultivation of Ps. menziesii in European forestry.     

国际木材价格波动对我国家具生产企业的影响

家具生产企业是我国制造业的重要组成部分。随着我国家具进出口贸易的不断发展,国际木材价格波动对我国家具生产企业的发展造成了严峻挑战。基于国际木材价格波动现状,分析国外木材原料的价格波动特征对国内木材原料市场异常价格波动带来的影响,以规避潜在的市场风险,促进国内家具企业的发展,在此基础上,有针对性地提出对策建议。     

Ecological consequences of Douglas fir (Pseudotsuga menziesii) cultivation in Europe

Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) was first introduced to Europe from North America more than 150 years ago, was then planted on a large scale and is now the economically most important exotic tree species in European forests. This literature review summarizes the current knowledge on the effects of Douglas fir on soil chemistry, plants, arthropods and fungi. Douglas fir shapes its abiotic environment similarly to native tree species such as Norway spruce, silver fir or European beech. In general, many organisms have been shown to be able to live together with Douglas fir and in some cases even benefit from its presence. Although the number of species of the ground vegetation and that of arthropod communities is similar to those of native conifer species, fungal diversity is reduced by Douglas fir. Special microclimatic conditions in the crown of Douglas fir can lead to reduced arthropod densities during winter with possible negative consequences for birds. The ecological impacts of Douglas fir are in general not as severe as those of other exotic tree species, e.g., Pinus spp. in South Africa and Ailanthus altissima, Prunus serotina and Robinia pseudoacacia in Europe. Nonetheless, Douglas fir can negatively impact single groups of organisms or species and is now regenerating itself naturally in Europe. Although Douglas fir has not been the subject of large-scale outbreaks of pests in Europe so far, the further introduction of exotic organisms associated with Douglas fir in its native range could be more problematic than the introduction of Douglas fir itself.     

Dendroclimatological regions of Douglas fir (<Emphasis Type="Italic">Pseudotsuga menziesii</Emphasis> Franco) in western Poland

Abstract Six Douglas fir (Pseudotsuga menziesii Franco) stands were selected in both the Sudety Mountains and the Great Poland Lowland. These two regions are distinctly different with regard to thermal and pluvial conditions. In each stand, two increment cores per tree were extracted from 20 approximately 100-year-old trees and the tree-ring widths measured. It is clear from the different growth reactions of the study trees to the climatic conditions that the Sudety Mountains and the Great Poland Lowland are two dendrochronologically separate regions. The tree-ring width chronologies form homogeneous groups for each region. The tree ring–climate models for Douglas fir in both regions indicate similarities and differences. The similarities among chronologies are attributed to winter temperature. The differences are attributed to rainfall (which changes with longitude and altitude of sites) during the vegetation season.     

Natural durability of Douglas fir (Pseudotsuga menziesii [Mirb.] Franco) heartwood grown in southern Germany

Abstract

The natural durability of timber is an important property in order to assess its performance in service. For numerous species grown in primary forests, this property has already been determined. As plantation-grown timber becomes more and more important, detailed information on its properties is needed, because increasing amounts of this material are coming to the market. The majority of planted Douglas fir (Pseudotsuga menziesii [Mirb.] Franco) in Germany is around 40 years old. In the present study, representative material of totally ten trees from two different sites in the south of Germany was investigated with regard to natural durability. In laboratory tests based on European standard DIN EN 350-1, inner and outer heartwood zones were exposed to basidiomycetes. Density measurements were additionally used for further characterisation of this material. Results showed a lower durability of the plantation-grown Douglas fir wood as compared with wood from natural sites. Significant differences for both durability and density were found between inner and outer heartwood, even though no correlation between the parameters was recognised. Data illustrate that for a better understanding of durability variations, chemical, topochemical and electron microscopic studies are needed.     

Feeding responses of the western dry-wood termite <Emphasis Type="Italic">Incisitermes minor</Emphasis> (Hagen) (Isoptera: Kalotermitidae) against ten commercial timbers

Five Japanese timbers, four timbers from the USA, and one Malaysian timber were evaluated for their resistance to the invasive dry-wood termite Incisitermes minor (Hagen) using laboratory choice and no-choice feeding tests with holed specimens. The highest survival rates of I. minor in both the heartwood and sapwood no-choice feeding tests were more than 70% after 3 months. When offered sapwood and heartwood choice feeding tests and the combined choice feeding tests, the highest survival rates of I. minor were more than 75% after 3 months. With regards to the percentage of wood mass losses in the no-choice and choice feeding tests, karamatsu (Larix leptolepsis), buna (Fagus crenata), and Douglas fir (Pseudotsuga menziesii) were classified as “resistant” species among the ten sapwood specimens. In the heartwood no-choice and choice feeding tests, the resistant species were buna, karamatsu, Douglas fir, sugi (Cryptomeria japonica), akamatsu (Pinus densiflora), and western red cedar (Thuja plicata). The ranking of the resistance of the ten commercial timbers against I. minor was buna > karamatsu > sugi > western red cedar > Douglas fir > rubber > western hemlock > hinoki > spruce.     

Shear tests of timber joints composed of sugi composite glulam beams using newly developed steel connectors

A research project supported by the Japan Wood Working Machinery Association has been conducted since 1999 to examine the feasibility of sugi (Cryptomeria japonica D. Don) composite glulam beams reinforced with Douglas fir (Pseudotsuga menziesii Franco) lamination. This study, part of the project, was concerned with the strength properties of timber joints composed of composite glulams using newly developed structural steel connectors. Two types of beam were prepared: 10 plies (inner 6 plies sugi, outer 4 plies Douglas fir) and 8 plies (inner 4 plies sugi, outer 4 plies Douglas fir). Two types of structural steel connector, Haratec and Standard, were used for joining the beam with a post or a girder. The relation between load and deformation of the joints was represented as a typical nonlinear curve. Initial stiffness and maximum load of the joint composed of the composite glulam were in the range between those of sugi and Douglas fir. Strength properties of the joints varied with three variables: type of connector, depth of the glulams, and the type of joint. Thus, the allowable loads for the connectors should be determined for each combination of these variables.     

Financial performance of mixed-age naturally regenerated loblolly-hardwood stands in the south central United States

To estimate the financial performance of a natural mixed species and mixed-age management in the loblolly-pine forest type, we examined 991 FIA plots in the south central states. The plots were of the loblolly pine forest type, mixed-age, and had been regenerated naturally. We gauged the financial performance of each plot from the equivalent annual income (EAI) produced by growth and harvest, between two successive inventories. The real price EAI (REAI) measured the financial performance based on the real price change, net of inflation, between surveys. The constant price EAI (CEAI) measured stand productivity at prices at the time of the first survey. Thus, the REAI is a measure of real economic performance, including timber growth and price changes. In contrast, the CEAI is a quantity index of timber growth, the growth of each product being weighted by its price. During the period 1977–1994, the main determinant of the REAI was the price change. Due to an overall favorable price trend, the mean REAI ($158 ha⁻¹ year⁻¹) was much greater than the mean CEAI ($24 ha⁻¹ year⁻¹). Due to increasing prices, the best performing plots had very high stocking levels. Thus, the best financial strategy was to hold the stock, making the opportunity cost of conservation negative. Instead, CEAI tended to be lower on stands with high basal area, and higher in stands with many trees, a low share of hardwoods, and many trees near sawtimber size.