Maximum Mean Annual Increment Research Articles

Effects of thinning on growth performance of teak (Tectona grandis) plantations in Tain II Forest Reserve, Ghana

Although recent interest in commercial teak plantation establishment has soared, knowledge of intensive silvicultural management of residual stands is limited in most parts of West Africa. This study evaluated the effects of thinning regimes on the growth responses and pruning requirements of teak plantations, two years after thinning, in the transition zone of Ghana. The thinning trial was conducted on a 4-year-old stand with initial stocking of 1 111 trees ha−1 in the Tain II Forest Reserve, Ghana. The treatments were four thinning regimes: 50%, 30%, 0% thinning intensities and 50% decrowning, arranged in a completely randomised design with four replicates. Two years after thinning, the treatments were significantly different in diameter at breast height (DBH) (p < 0.00029), total height (p = 0.017) and stem density (p < 0.0002). The 50% thinning intensity had the highest mean tree DBH, volume, height and basal area of 15.57 cm, 0.13 m3, 11.94 m and 0.02 m2 respectively. The lowest was found in the control (no thinning) except height which was least in decrowned plots. Maximum mean annual increment of DBH, total height and volume were respectively 2.00 cm, 1.34 m and 9.9 m3 ha−1 for the heavily thinned stand. The number of epicormic shoots per tree increased with the thinning intensity/regime, hence increasing the pruning requirement. It is concluded that 50% thinning intensity promotes positive growth of residual stand but increases the pruning requirements and possibly the pruning costs. Long-term evaluation of this trial is essential to validate the recommendations from this study.

Developing and Comparing Individual Tree Growth Models of Major Coniferous Species in South Korea Based on Stem Analysis Data

Tree growth in Korean red pine (Pinus densiflora, hereafter Pd), Korean white pine (Pinus koraiensis, hereafter Pk), and Japanese larch (Larix kaempferi, hereafter Lk) was modeled using Logistic, Korf, Gompertz, Chapman-Richards, and Weibull equations and stem analysis data from sample trees: 38 trees for Pd, 46 trees for Pk, and 45 trees for Lk. The models were fitted to the total increment of tree size variables, diameter at breast height (DBH), height, basal area, and stem volume, as a function of age. After selecting the best-fit growth function, the current annual increment (CAI) and mean annual increment (MAI) were compared for each variable by species. The optimal growth functions were Chapman-Richards for DBH and stem volume, Korf for height, and Gompertz for basal area. The parameter estimates in the final models were all significant (p &lt; 0.01) with best-fit statistics and unbiased residual plots. When plotted with observed values, the growth patterns of each variable were represented properly. The predicted growth curves over age were concave with respect to the Y-axis in DBH and height but lightly convex in basal area, and explicitly convex in stem volume, whereas an asymptote of sigmoid curve in stem volume was not apparent until 100 years. Age with the maximum MAI among variables was arranged similarly to CAI; the age with maximum MAI was earliest for DBH and latest for volume. The maximum growth was achieved earliest in Lk, followed by Pk and Pd. The developed models were able to predict tree size variables and serve as a reference to understand growth characteristics by species.

An analysis of conifer experiments in Britain to identify productive alternatives to Sitka spruce

Abstract As the climate changes there is a need to reduce the reliance on Sitka spruce (Picea sitchensis (Bong) Carr.) in upland British forestry and increase species diversity to lower the risk of damage or loss of production due to biotic or abiotic events. An analysis of relevant species trials was carried out to assess the productivity of potential alternative conifer species on upland site types in Britain. Data from 87 forest experiments planted between 1929 and 1995 were analysed to compare long-term performance of 52 species with that of Sitka spruce under the same conditions and site type. Sites were broadly categorized using soil and climatic factors, which were used as primary factors in models predicting General Yield Class (GYC, the maximum mean annual increment in m3 ha−1 year−1) of the potential alternative species and of Sitka spruce. No species had significantly higher GYC estimates than Sitka spruce, but grand fir (Abies grandis (Douglas ex D. Don) Lindl.), noble fir (Abies procera (Rehder)), western hemlock (Tsuga heterophylla (Raf.) Sarg.), Lutz’s spruce (Picea x lutzii (Little)), maritime pine (Pinus pinaster (Aiton)), Lawson cypress (Chamaecyparis lawsoniana (A. Murray bis) Parl.), Scots pine (Pinus sylvestris (L.)), Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) and western red cedar (Thuja plicata (Donn ex D.Don)) all had GYC estimates which were not significantly lower than that of Sitka spruce under certain soil and climate conditions. A further 26 species, particularly Abies species, had GYC within 3 m3 ha−1 year−1 of Sitka spruce but were present on too few sites for inclusion in statistical models. The results of the analysis provide objective evidence for the planting of a wider range of species where Sitka spruce may currently be first choice. In the absence of any major pest or disease affecting Sitka spruce, it is still a good choice for many upland sites, however, a wider range of options with equivalent productivity exist, allowing forest managers to diversify and reduce the risk of damage or loss of production due to biotic or abiotic events.

Analysis of optimum age and maximum increment of forest stands for developing community forests

The community forests are one of the main suppliers of wood needs in the future. They require careful attention to the wood type to be planted, preferably choosing plants that have a short cycle. The demand for wood for the community is increasing, while the supply of timber from state forests to the wood processing industry is decreasing. This research aimed to analyze the optimum age and maximum increment of community forest stands and which species were more profitable. This research was done in a community forest with tropical environmental type. This research was quantitative, calculating the maximum volume cycle and Mean Annual Increment (MAI) values in community forest stands. The results show that the maximum volume increment was found in jabon (Anthocepalus sp) stands, namely at the age of 8 years, with a total of 600 trees/ha, an average diameter of 30 cm, an average height of 13 m, a total volume of 330.64 m3/ha, and a mean annual increment (MAI) of 41.33 m3/ha/year. Jabon stands at the age of 8 years were suitable for harvest because they reached the maximum volume increment in the soil types of Hapludults Dystrudepts, Haplustepts Haplustalfs, and Endoaquepts Udifluvents

Modelling potential yield capacity in conifers using Swedish long-term experiments

Information on forest site productivity is a key component to assess the carbon sequestration potential of boreal forests. While site index (SI) is commonly used to indicate forest site productivity, expressions of SI in the form of yield capacity (potential maximum mean annual volume increment) is desirable since volume yield is central to the economic and ecological analyses of a given species and site. This paper assessed the functional relationship between SI and yield capacity on the basis of yield plot data from long-term experiments measured over several decades for Norway spruce (Picea abies), Scots pine (Pinus sylvestris), Lodgepole pine (Pinus contorta) and Larch (Larix decidua and Larix sibirica) in Sweden. Component models of total basal area and volume yield were also developed. SI was determined by existing height development functions using top height and age, whereas functions for stand-level (m2 ha−1) basal area development were constructed based on age, SI and initial stand density using difference equations and nonlinear mixed-effects models. The relation between volume yield (m3 ha−1) and top height was adjusted with total basal area production through nonlinear mixed-effects models. Species-specific parametric regression models were used to construct functional relationships between SI and yield capacity. The root mean square errors of the species-specific models ranged from 2 to 6% and 10–18% of the average values for the basal area and volume equations, respectively. For the yield capacity functions, the explained variations (R2) were within 80–96%. We compared our yield capacity functions to earlier functions of the species and significant differences were observed in both lower and higher SI classes, especially, for Scots pine and Norway spruce. The new functions give better prediction of yield capacity in current growing conditions; hence, they could later be used for comparing tree species’ production under similar site and management regimes in Sweden.

Dendrochronological study of Cedrus deodar Grown at Kumrat valley Dir Upper KPK, Pakistan: Evaluation of Tree Age and Increment Based on Increment Core

The present research was conducted for tree-rings study in a mixed stand of Himalayan Species Credur deodar in Kumrat valley Dir Upper KPK, Pakistan. Tree-rings analysis was related to the counting of tree ring. Random sampling method was used, and 70 sample trees were selected, tree heights and diameters were measured, and increment cores were collected from each sample-tree diameter at the height at breast point to be analyzed and studied in the laboratory. The objectives of the study were to determine the exact age of tree and to evaluate total and mean annual increment in the basal area and tree volume based on the increment cores. Regression models revealed the impacts of tree age on the basal area and tree-volume increment. Results showed the minimum basal-area increment was 0.0028 m2 at the age of 10 years, the maximum basal-area increment was 2.658 m2 at the age of 60 years, with mean was 0.95±0.677 m2 at the age of 36 years and R2 was 0.9593. The maximum tree-volume increment was 1.42 m3 at the age of 60 years, the minimum tree-volume increment was 0.010 m3 at the age of 10 years, with mean was 1.35±0.96 m3 at the age of 36 years and R2 was 0.9167. The minimum mean annual-basal area increment was 0.0027 m2, the maximum mean annual-basal area increment was 0.048 m2, and the average increment was 0.022±0.010 m2. The maximum mean-annual increment in tree volume was 0.068 m3 at the age of 60 years, the minimum mean-annual increment was 0.0039 m3 at the age of 10 years, with mean was 0.032±0.014 m3 at the age of 36 years and R2 was 0.8903. Results showed a strong positive relationship of tree age with area and volume increment.&#x0D; Keywords: Basal area, increment, tree age, volume

The evolution in time of the concept of fast growing tree species: is it possible to use a definition applicable to all environmental conditions?

Although the expression “fast-growing species” (FGS) referred to tree species has been since long time used, a clear definition has not been adopted for decades. Starting from the Italian historical background, we searched for the definitions of FGS formulated over time at a national and international level. The mean annual increment (MAI) of 10 m 3 ha -1 , identified by the FAO, has been the most commonly considered threshold until recently. Subsequently, experimental activities and research efforts have consistently enhanced the productivity of FGS, and other definitions have been proposed accordingly. Hence, FGS should provide annual wood yields of 15-25 m 3 ha -1 with rotations of less than 25-30 years. In Europe, the maximum MAI can reach about 20-25 m 3 ha -1 , while in fast-growing tropical plantations the MAI frequently exceeds 30-35 m 3 ha -1 . However, we deem that the threshold of 10 m 3 ha -1 year -1 is still reliable for Mediterranean conditions. Since the fast-growing is a relative concept, strongly affected by species’ traits, environmental conditions and cultural practices, a future increase in the productivity levels of wood plantations can be expected.

Repeatability of growth characteristics and wood properties for solid wood production from Eucalyptus camaldulensis half-sib families growing in Thailand

Abstract To promote solid wood production, the diameter at breast height, height, stress-wave velocity, surface-released strain, basic density and compressive strength parallel to the grain were measured for 10 half-sib families of 12-year-old Eucalyptus camaldulensis Dehnh. trees growing in Thailand. Based on the results, growth rates, correlations among measured properties, radial and among-family variations of wood properties, and their repeatability were evaluated. Diameter at breast height, height, and wood volume were exponentially increased at initial stage, and then gradually increased toward to 12 years after planting. The maximum current annual increment and mean annual increment in wood volume showed at age of 8 and 11years old, suggesting that rotation period for optimum productivity may be ranged from 8 to 11 years old. Wood with stable properties was found greater than 6 cm from the pith. These results indicate that 12-year-old E. camaldulensis trees had already reached the maturation stage. No significant correlations were found between growth characteristics and wood properties. Significant variances in the height, stress-wave velocity, and basic density were found among the 10 families. The F-values and repeatability of the wood properties in the outer wood were higher than those in the inner wood. These results indicate that the properties of the outer wood are closely related to genetic factors. Thus, to obtain superior E. camaldulensis trees for solid wood production, the family selection should be conducted using the outer wood of aged trees.

Assessing site form as an indicator of site quality in even-aged Pinus radiata D. Don stands in north-western Spain

Key messageSite form and site index have shown similar precision for estimating site quality in even-agedPinus radiataD. Don stands in north-western Spain. Additionally, SF presents the advantage that it does not require stand age information and can therefore be used in a wider set of situations in the forestry practice.ContextEstimation of site quality is essential for characterizing, monitoring and predicting forest resources. Site index (i.e. the dominant height of the stand at a reference age) is ordinarily used to estimate site quality; however, this index is only useful for even-aged stands of known age. By contrast, SF is age-independent as it uses the dominant height of the stand at a reference dominant diameter.AimsThe aim of this study was to compare the performance of SF and SI for site quality estimation in even-aged P. radiata stands.MethodsDynamic equations derived with the Generalized Algebraic Difference Approach (GADA) from the Hossfeld IV base model were fitted to predict site quality with both SI and SF. SF predictions were compared with SI regarding variability within the same plot and consistency in site quality predictions, using the observed maximum mean annual volume increment (MAI) as a direct measure of site quality.ResultsBoth approaches showed good performance in model fitting and provided similar goodness-of-fit statistics and variability in the predictions. However, SI performed slightly stronger when related to MAI.ConclusionSF performed adequately in estimating site quality for even-aged P. radiata stands, with results comparable to those obtained using traditional SI.

Production of hybrid aspen on agricultural land during one rotation in southern Sweden

High potential productivity together with short rotation periods have made hybrid aspen an interesting option for wood production on former arable land in Nordic countries. In this study, some of the oldest active experimental plots with hybrid aspen in Sweden were remeasured at 23–30 years of age. A main aim was to assess age and productivity at the time of maximum mean annual volume increment. In addition, the influence of commercial thinning on stand development and differences in genetic gain among clones were investigated. Data from five experiments in southern Sweden were used, including three genetic trials, one demonstration stand with a clone mixture and one stand regenerated from root suckers. The three genetic trials were treated as single plot experiments, subject to a standard thinning program. In the remaining experiments, different thinning strategies were tested in a balanced block design. Volume growth had culminated or was close to maximum at age 25–30 years. Mean annual stem volume increment at culmination was 20–22 m3 ha−1 a−1. Dominant height reached 30–35 m at 28–30 years of age. Mean diameter at breast height was 27–29 cm after 29–30 years in the genetic trials. Clonal ranking based on diameter at age 7–9 years was positively correlated with the ranking at the final measurement in the genetic trials, 20 years later. This indicates that clones can be selected for superior growth based on results from young trials. More intense thinning programs increased the mean diameter compared to light thinning. The study indicates that one or two early and relatively heavy thinnings can promote the development of crop trees, without jeopardizing total volume production during a rotation of 25–30 years.

Nutrient Management and Carbon Sequestration Potential of Rubber-based Intercropping system in Western Ghat Region of Karnataka

The present field experiment entitled ‘Nutrient management and carbon sequestration potential of the rubber-based intercropping system in Western Ghat region of Karnataka’ was conducted at farmers’ field of Harishi village of Soraba taluka of Shivmogga District, Karnataka, India during 2017 to 2019. The experiment was laid out in split-plot design with three replications. Two practices applied on rubber was the application of Farm Yard Manure (FYM) as an organic practice and NPK as inorganic practice and nine treatments consisting of different organic manures biofertilizers and NPK as inorganic fertilizer was applied on Bird’s Eye Chilli (BEC) grown as an intercrop. The results showed that application of NPK on rubber resulted in a maximum mean annual increment in basal diameter (0.56 cm) and crown diameter (0.28 m) in one-year-old rubber and height (0.77 m), basal diameter (0.62 m) crown diameter (0.21 m) in two-year-old rubber. Among nine treatment of BEC, application of NPK resulted in higher growth parameters of rubber at both age levels. Interactions were non-significant on all growth parameters. Age and different manures also influenced the carbon sequestration potential of the system. Hence the application of NPK may be recommended for cultivation of rubber.

Community forest management: Comparison of simulated production and financial returns from agarwood, tengkawang and rubber trees in West Kutai, Indonesia

Lahjie AM, Isminarti, Simarangkir BDAS, Kristiningrum, R, Ruslim Y. 2018. Community forest management: Comparison of simulated production and financial returns from agarwood, tengkawang and rubber trees in West Kutai, Indonesia. Biodiversitas 19: 126-133. Research was conducted in planted forests of agarwood (Aquilaria spp.) and tengkawang (Shorea macrophylla) and in plantations of natural rubber (Hevea brasiliensis) in West Kutai District, East Kalimantan Province, Indonesia. The research aimed (i) to find out the productivity of agarwood and tengkawang trees in mixed plantings (ii) to measure their rate of development in order to estimate the maximum Mean Annual Increment (MAI) for agarwood and tengkawang and (iii) to carry out a comparison with natural rubber production of the investment feasibility of planted forests of these trees using a financial analysis of Pay Back Period, Net Present Value (NPV), Net Benefit/ Cost (B/C) Ratio and Internal rate of Return (IRR). The research was based on measurements carried out in plots, 0.25 ha in extent, selected by systematic random sampling from three model plantations. Plantation Model I was a combination of agarwood and tengkawang in one piece of land in which the agarwood trees were planted at a spacing of of 5m x 2.5m and the tengkawang tree were also planted at a spacing of 5m x 2.5m. This means that there were a total of 200 agarwood saplings and 200 tengkawang saplings in the plot. Model II was the combination of agarwood and tengkawang in one piece of land, in which 167 agarwood saplings were planted and 166 tengkawang saplings were planted in a different planting arrangement (at the planting distance of 5m x 3 m). Model III was rubber trees in an area of 0.25 ha with 119 saplings. The data for natural rubber were collected in series from the farmers. The measurement variables for agarwood and tenkawang included the diameter and height of trees using series measurement until they reached 30 years and then the results were simulated. The research findings showed that in Model I, agarwood was found to have higher maximum MAI while in Model II, tengkawang was found to have higher maximum MAI. This was the result of a silvicultural technique in which thinning, maintenance and intermediate harvest were carefully controlled. These two models were feasible for business because the values of their IRR were 14% and 13.3% respectively, while in Model III, rubber cultivation was not feasible for business because the value of its IRR was only 4.7%.

Scenario analysis of planting density and pre-commercial thinning: will the mixed forest have a chance?

In the establishment phase, several management alternatives could be applied that affect the species composition of the future stand. In this study, tree seedling data from experiments with planted Norway spruce (Picea abies L. Karst) and naturally regenerated species, mainly Silver birch (Betula pendula Roth), were used for six simulated pre-commercial thinning (PCT) scenarios. The scenarios included both monocultures and mixed stand alternatives with various initial spacing of the planted Norway spruce (0, 1600 or 2800 seedlings) and selection of main stems based on relative heights. Further stand development and individual tree growth were simulated until final harvest. Potentially, based on findings of the seedling measurements, the stands could be mixed with five to six species, but the browsing pressure from ungulates reduced this possibility since the height growth for all species except Norway spruce was highly affected by browsing. The simulated mixtures had a small variation between the PCT scenarios for the maximum mean annual increment (about 10 %). Although the growth was similar for Norway spruce, the proportion of birch in the final stands differed from 3 to 21 % between treatments and none of the high-density planting treatments generated a mixed Norway spruce–birch forest at the time of final felling.

Growth of intact plants and coppice in short rotation eucalypt plantations

The growth of intact plants and coppice of juvenile plants of eight eucalypt clones (3 × 3 m spacing) was evaluated in the savanna region, Brazil (17°36′09″S and 46°42′02″W), aiming for biomass production for energy in short rotations. The treatments included intact plants and juvenile plant coppice (cut at 13 months of age). Coppice was managed either with thinning to two sprouts/stump at 9 months after harvesting or without sprout thinning. The diameter of the intact plants was greater than that of coppice for clones 58, GG100, 26 and 8B, and no differences were noted between treatments for the other clones. Yield did not differ between the thinned and unthinned sprouts for most clones. At younger ages, the coppice yield was greater than that of the intact plants for most clones. Later, there was a decline in the coppice yield, and intact plants surpassed coppice. Then, the maximum coppice mean annual increment was achieved at younger ages than for the intact plants, which resulted in coppice rotation age shortening. The greatest differences between the coppice and intact plants yield was between 38 and 40 months, when the coppice yield was 59, 56, 127, 149 and 75 % greater than that of the intact plants, for the clones 58, GG100, 1000, 36 and 910, respectively. Clone GG100 revealed the highest yield estimation among the intact and coppice plants. The results indicate that by coppicing juvenile eucalypt clone plants, in dense stands, it is possible to produce biomass for energy, without sprout thinning, if rotation age is shortened.

Growth and thinning effects during a rotation period of hybrid aspen in southern Sweden

Hybrid aspen is an interesting tree species for wood production in northern Europe. In this study we examined growth dynamics over the whole rotation period. Height and diameter development, as well as annual growth of stem volume and stem biomass, were repeatedly recorded in 14 planted and 2 root sucker stands, aged up to 26 years, in southern Sweden. A main aim was to study the productivity level for hybrid aspen forestry with an expected rotation period of about 25 years. The study verified earlier prognoses, showing a mean annual increment (MAI) of 19.5 m3 of stem wood ha−1 yr−1 after 25 years. This corresponds to a dry weight of stem biomass of 7.2 tons dry matter (DM) ha−1 yr−1. Maximum MAI was still not reached after 25 years, although the growth curve was flattening out. If branch biomass is included, MAI is estimated to about 9 tons DM ha−1 yr−1 and further improvements in growth is expected by using the best genotypically selected clones available. Results from three different thinning regimens showed that thinning intensity provided significantly larger diameter growth, while no significant yield effects were seen among the thinning regimens.

Optimal regeneration method – Planting vs. natural regeneration of Scots pine in northern Sweden

In this study the profitability of regenerating Scots pine (L.) was examined for two methods; planting and natural regeneration with seed trees. The methods were modelled on stand level and optimised numerically using nonlinear optimisation. The analysis includes 7 site indexes, 16 to 28 expressed as dominant height in meters at an age of 100 years; and 8 localities in northern Sweden distributed on two latitudes, 60°N and 64°N and four altitudes, 100 to 400 m.a.s.l. Furthermore, two scenarios of genetically improved planting material were examined. The results show that the optimal choice of regeneration method depends on the location, site index and discount rate. Considering the same genetic regeneration material, natural regeneration was the optimal method for most of the evaluated sites. Planting was optimal only for stands of high site index and low rate of seedling mortality, which is associated with localities on low altitudes. The break even site index, where the two methods yielded the same net present value, was 27 on average (25 to 28). The choice between the two regeneration methods was found to be more economically important when the discount rate was low and for low site indexes. The option of using genetically improved plant material shift the preference towards planting. Thus, the two levels of genetic gain of +4% and +10% to maximum mean annual increment resulted in an average break even site index of 25 and 21 respectively.Pinus sylvestris

Growth and yield of nine pine species in Angola

A species introduction experiment including several tropical pines and eucalypts was established in 1966/1967 in the Tchianga research station in Angolan Highlands. Despite 27 years of political conflict (1975–2002) and lack of management, the research experiment has remained relatively well conserved. We measured the best conserved plots that were 41 years old in 2007 to obtain information on the growth of different pine species. We calculated stand characteristics including basal area, dominant height, mean diameter, and stand volume for Pinus patula Schiede ex Schiltdl. Et Cham., Pinus pseudostrobus Lindl., Pinus kesiya Royle ex Gordon, Pinus devoniana Lindl., Pinus chiapensis (Martinez) Andresen, Pinus elliottii Engelm., Pinus greggii Engelm. Ex Parl., Pinus montezumae Lamb. and Pinus oocarpa Schiede ex Schltdl. The growing stock volume at 41 years was the highest in P. pseudostrobus, 1,325 m3·ha−1, followed by P. kesiya with 1,200 m3·ha−1. The widely planted P. patula had a growing stock volume of 892 m3·ha−1. P. oocarpa and P. pseudostrobus had the highest stand basal area, over 80 m2·ha−1. Using increment core analyses we studied the temporal development of stand characteristics. Analysis of the mean annual increment (MAI) showed that rotation lengths of 20–30 years would maximize wood production. With these rotation lengths, the MAI of P. pseudostrobus would be 35 m3·ha−1. Other productive species were P. kesiya, P. oocarpa and P. chiapensis. P. patula had a maximum MAI of 20 m3·ha−1. P. greggii had the lowest mean annual volume production, only about 13 m3·ha−1.

Productivity of Norway spruce compared to Scots pine in the interior of northern Sweden

Productivity of Norway spruce (Picea abies L. Karst.) and Scots pine (Pinus sylvestris L.) was studied in 12 paired plots in the interior of northern Sweden. Stands were established between 1928 and 1959; yield plots were established between 1974 and 1983 during pre-commercial thinning of the stands. Gross stem-wood production was significantly higher for Scots pine than for Norway spruce, stem-wood production by Norway spruce being 29.4% that of Scots pine. The site index for Norway spruce was lower than for Scots pine at all sites except one; the average difference in site index was 4.8 m. The simulated maximum mean annual increment (MAI) during the rotation was 19% higher than the MAI estimated with the site index for Scots pine, whereas simulated MAI and MAI estimated from the site index was about the same for Norway spruce. The simulations also indicated that MAI peaked about 50 years later for Norway spruce than for Scots pine. More small trees were included in the diameter distribution of Norway spruce than of Scots pine resulting in a lower stem-wood volume for Norway spruce when stands with the same dominant height were compared. This study shows that the difference in growth and rotation length between Scots pine and Norway spruce has implications when choosing which species to grow in the interior of northern Sweden.maxmaxmaxmax

On Relative Maxima of Diameter Growth, Basal Area Growth, Volume Growth, and Mean Annual Increment for Individual Trees

Abstract A mathematical demonstration for the fact that maximum individual tree diameter growth occurs at an earlier age than maximum individual tree basal area growth is reviewed. This demonstration assumes that the growth functions are continuous, are twice differentiable with respect to age, and increase monotonically to one maximum, thereafter to decline monotonically. The relationship of the age of maximum individual tree volume growth to the age of basal area growth is also discussed. Mathematical demonstrations are given for the fact that the culmination of mean annual increment occurs earlier for diameter than for basal area, and results on age of maximum growth and mean annual increment are also given for arbitrary power functions in diameter.

Comparison of the Growth of SixEucalyptusSpecies in Angola

Eucalyptusspecies have been planted in Angola since the early twentieth century. The species introduction experiment of Tchianga, in the Angolan Highlands, was established in 1966/1967. The experiment included several tropical pines and eucalypts. The plots were 43 years old when measured in 2009. Species includedEucalyptus salignaSm.,E. camaldulensisDehnh.,E. macarthuriiH. Deane &amp; Maiden,E. resiniferaSm.,E. siderophloiaBenth., andE. grandisHill ex. Maiden.E. salignahad the highest stand volume at 43 years (1427 m3 ha−1), followed byE. grandis(1006 m3 ha−1).E. macarthuriiandE. camaldulensishad the lowest stand volume (423 and 511 m3 ha−1, resp.). Using X-ray analyses of increment cores, it was possible to study the temporal development of the stand characteristics. An analysis of the mean annual increment showed that the optimal rotation length for most of the studied eucalypts is around 22 years with the exception ofE. resinifera, for which 12–15 years is the best.E. salignahad the highest maximum mean annual increment (MMAI) of 37 m3 ha−1attained at 22 years of age.E. grandisreached its MMAI of 25 m3 ha−1at 28 years. The results suggest thatE. salignais the most recommendedEucalyptusspecies for new plantations in Angola.