Timber Volume Research Articles

MultiProduct Optimization of Cedrelinga cateniformis (Ducke) Ducke in Different Plantation Systems in the Peruvian Amazon

This study addressed multi-product optimization in Cedrelinga cateniformis plantations in the Peruvian Amazon, aiming to maximize volumetric yields of logs and sawn lumber. Data from seven plantations of different ages and types, established on degraded land, were analyzed by using ten stem profile models to predict taper and optimize wood use. In addition, the structure of each plantation was evaluated using diameter distributions and height–diameter ratios; log and sawn timber production was optimized using SigmaE 2.0 software. The Garay model proved most effective, providing high predictive accuracy (adjusted R2 values up to 0.963) and biological realism. Marked differences in volumetric yield were observed between plantations: older and more widely spaced plantations produced higher timber volumes. Logs of optimal length (1.83–3.05 m) and larger dimension wood (e.g., 25.40 × 5.08 cm) were identified as key contributors to maximizing volumetric yields. The highest yields were observed in mature plantations, in which the total log volume reached 508.1 m3ha−1 and the sawn lumber volume 333.6 m3ha−1. The findings demonstrate the power of data-driven decision-making in the timber industry. By combining precise modeling and optimization techniques, we developed a framework that enables sawmill operators to maximize log and lumber yields. The insights gained from this research can be used to improve operational efficiency and reduce waste, ultimately leading to increased profitability. These practices promote support for smallholders and the forestry industry while contributing to the long-term development of the Peruvian Amazon.

Crecimiento del “shihuahuaco” Dipteryx ferrea (Ducke) Ducke en plantaciones bajo diferentes espaciamientos y tipos de suelo en Ucayali, Amazonía peruana

The results of experimental trials with Dipteryx ferrea (Ducke) Ducke, a forest species commonly known as "shihuahuaco", established under four different forest and agroforestry systems at the Alexander von Humboldt Experimental Center, Ucayali, at an altitude of 225 meters above sea level, are presented. These systems were differentiated by spatial arrangement, initial spacing, soil type, and were 11 years old. Measurements of total height, diameter at breast height (DBH), basal area, and timber volume of the plantations were obtained. The results demonstrate the growth potential, survival, and productivity of D. ferrea in both pure and mixed open-field plantations. System 1, on Plinthic acrisol soil, flat physiography, and 5 × 5 m spacing, showed the highest average DBH, total height, and dominant height, with values of 20.23 cm, 13.9 m, and 16.8 m, respectively. These results are statistically superior (p < 0.05) to those of other analyzed plantations and indicate promising performance. In terms of productivity, system 3, on Plinthic gleysol soil, flat physiography, and 2 × 2 m spacing, exhibited the highest values of basal area and roundwood volume, with 38.40 m2 /ha and 243.3 m3 /ha, respectively, statistically superior to the other systems, but also heavily influenced by the high plantation density. These findings suggest encouraging prospects for establishing D. ferrea plantations in forestry settings.

Quantitative Genetic Aspects of Accuracy of Tree Biomass Measurement Using LiDAR

The growing focus on the role of forests in carbon sequestration highlights the importance of accurately and efficiently measuring biophysical traits, such as diameter at breast height (DBH) and tree height. Understanding genetic contributions to trait variation is crucial for enhancing carbon storage through the genetic improvement of forest trees. Light detection and ranging (LiDAR) has been used to estimate DBH and tree height; however, few studies have explored the heritability of these traits or assessed the accuracy of biomass increment selection based on them. Therefore, this study aimed to leverage LiDAR to measure DBH and tree height, estimate tree heritability, and evaluate the accuracy of timber volume selection based on these traits, using 60-year-old larch as the study material. Unmanned aerial vehicle laser scanning (ULS) and backpack laser scanning (BLS) were compared against hand-measured values. The accuracy of DBH estimations using BLS resulted in a root mean square error (RMSE) of 2.7 cm and a coefficient of determination of 0.67. Conversely, the accuracy achieved with ULS was 4.0 cm in RMSE and a 0.24 coefficient of determination. The heritability of DBH was higher with BLS than with ULS and even exceeded that of hand measurements. Comparisons of timber volume selection accuracy based on the measured traits demonstrated comparable performance between BLS and ULS. These findings underscore the potential of using LiDAR remote sensing to quantitatively measure forest tree biomass and facilitate their genetic improvement of carbon-sequestration ability based on these measurements.

Increasing timber and declining live plant diversity and volumes in global trade from 2000 to 2020

Plants are a vast, lucrative portion of global wildlife trade and the most speciose clade listed under the Convention on International Trade in Endangered Species of Wild Fauna and Flora-CITES. Here we used the CITES Trade Database and >420,000 records between 2000 and 2020 and assessed the diversity and volume of wild-sourced CITES-listed plants across space and time. Between 2000–2020, over 8.4 million cubic metres of timber, 197 million individual live plants, and 4.6 million kilograms of plant products were traded under CITES, comprising 53, 765, and 74 species, respectively. Most species are traded between key exporter and importer nations, especially China, USA, and Europe. Total diversity of timber species and volumes increased over time, whereas live diversity declined, and product diversity and mass fluctuated uncertainly. Most species were not evaluated by the International Union for the Conservation of Nature (IUCN) Red List when first traded, with high volumes of timber and products concentrated among threatened taxa. The high prevalence of poorly understood species necessitates enhanced rigour in ensuring sustainable CITES trade.

Characteristics of the process of tree mortality occurring in the Polish Sudetes Mts

Abstract The forests of the Sudetes Mts are among the ecosystems most threatened by climate change in Poland. Abiotic factors cause the threat, such as an increase in the average annual temperature and a clear change in the distribution of atmospheric precipitation intensity during the year. The aim of the study is to characterise the process of tree mortality, especially spruce, the main forest-forming species of the region, in the Sudetes. The analyses carried out covered 12 forest districts belonging to the Regional Directorate of State Forests in Wrocław. Calculations made with the stand growth model showed that the total volume of merchantable timber in the forest districts is about 58 million m3, of which 68% consists of spruce. Two indices characterising the process of tree dieback, that is, tree dieback index (the volume of deadwood of a specific tree species harvested in the period 2011–2022) and tree dieback intensity coefficient (the quotient of the volume of deadwood harvested after the occurrence of the main cause of tree dieback and the volume of deadwood harvested before the occurrence of this cause there) were applied. The threat process intensified in 2015, when drought during the vegetation season caused massive thinning of trees and breakdown of tree stands, especially spruce stands and, to a lesser extent, pine and larch stands, and the least of all, birch, alder and beech stands. Therefore, it was assumed in the study that it is the ratio of the volume of deadwood obtained in the periods 2015–2018 and 2019–2022 to the volume of deadwood obtained in the period 2011–2014. There is an urgent need to change the concept of forest management in Poland. In the field of silviculture, it should include in particular: a) planning the species composition of tree stands, adapted to the changing of their growth conditions; b) a critical approach to the methods of forest management, including harvesting system and c) a critical verification of the methods used to determine the action level of cutting management, especially harvesting systems, and the order of selection of tree stands for the implementation of these treatments.

Biomass as an energy source and carbon stock

Abstract The present study demonstrates the importance of biomass as a renewable energy source; the forest ecosystems with high-energy potential have a high carbon storage capacity and the key factor being the amount of biomass stored. The study area was Romania, located in Europe, where the author selected 90 forest ecosystems spread along an altitudinal gradient from the lower Danube floodplain (15 m asl.) to the Carpathian Mountains (2100 m asl.). In each ecosystem type, five circular areas of 500 m2 were selected, where the following parameters were measured and estimated: tree species composition, average age, total timber volume (m3/ha) and annual productivity (m3/ha/year), and wood density (g/cm3). The calorific capacity of the wood was determined by calorimetric methods using the Bomb Calorimeter (Model-IKA C2000), the carbon content was measured with a CE InstrumentsEA-1110 CHNS-O dispositive, and the carbon stock was calculated using CO2FIX31EXE based on woody biomass carbon stocks. From the point of view of standing crop biomass, the most valuable are pure forests, 130-year-old (355 t/ha); mixed beech forests where beech dominates, 110-year-old (300.8 t/ha); and the planted forest, the 35-year-old poplar plantation was the most productive (199.5 t/ha). The highest productivity was in the 10-year-old planted poplar forest (7.14 t/ha/year), followed by the 110-year-old sessile oak forest (2.35 t/ha/year), and 110-year-old mixed beech forests, where 50% beech in composition. In natural forests, in terms of energy, the most efficient are pure beech forests and those mixed with fir and spruce, and for the planted forest, it is the poplar forest. A direct correlation is between the capacity to produce and store energy of the forest ecosystems and the capacity to fix and store the carbon through photosynthesis, and the biomass is a key factor that proves this.

Improving airborne laser scanning-based species-specific forest volume estimation using sentinel-2 time series

ABSTRACT Species-specific timber volume estimates are required to support forest planning and conservation. We evaluated whether additional predictors from a Sentinel-2 time series can improve airborne laser scanning (ALS)-based estimation of species-specific timber volumes. Furthermore, we determined the satellite image dates that provided the greatest improvement in accuracy. The Sentinel-2 time series was constructed to cover 1 March–30 November time-period, with a focus on late spring and early summer. The estimation was done using the k Most Similar Neighbor method and predictors extracted from the ALS data and Sentinel-2 images. Our best model included both ALS and Sentinel-2 time-series predictors, and the relative root mean square error (RMSE) values for pine, spruce and deciduous timber volumes were 40.8%, 57.0% and 51.3%, respectively (mean 49.7%). All deciduous trees were treated as one species. When bands from an individual image were used instead of the time series, the best result was obtained with an image from September where the respective relative RMSE values were 42.2% (deciduous), 58.4% (pine) and 60.6% (spruce) with a mean value of 53.7%. A fusion of a Sentinel-2 time-series and ALS data can improve species-specific estimation results compared to the use of individual Sentinel-2 images or ALS only.

DOES RESIN TAPPING AFFECT THE TAPERING AND ACCUMULATION OF MERCHANTABLE TIMBER VOLUME IN PINE TREES?

Form factors and taper functions are used for the quantitative and qualitative description of tree stem shape. In southeastern Mexico, there are plantations of Pinus caribaea var. hondurensis (Sénécl.) W.H. Barrett & Golfari, Pinus elliottii var. elliottii Engelm., and hybrids between these species to simultaneously produce resin and wood. Farmers need to know whether the practice of resin tapping to death has a negative impact on tree shape and volume of the wood produced. To answer these questions, this study compared the shape, taper, and volume of resin-tapped and untapped trees from three P. caribaea origins. A total of 198 trees (99 resin-tapped and 99 untapped) were measured in all diameter categories of the plantation. Total volume models, along with a compatible taper system and variable merchantable timber volume, were fitted using linear and nonlinear regression analyses. To compensate for the lack of initial tree size data prior to tapping, indicator variables (dummies) and an additive structure were used to parameterize volume and taper models. Untapped trees accumulated greater volume than tapped trees. In contrast, the form factor (ff) of resin-tapped trees (ff = 0.51) was greater than that of untapped trees (ff = 0.45). The form factor increased due to tapping between 4 and 7 % depending on the origin, although the hybrid P. caribaea × P. elliottii presented the most desirable stem geometry in tapped and untapped trees. Based on the Demaerschalk model, the variability is estimated at 99 and 97 % of the merchantable and taper volumes, respectively.

A promising hardware and software complex for determining the volume of crushed wood

Modern software and hardware complexes for determining the volume and accounting of round timber are well known and are successfully used at timber enterprises of the Russian Federation. At the same time, a number of enterprises in the forestry industry working with technological chips (pulp and paper mills, plants for the production of wood slabs), as well as biofuel plants, have an urgent need to promptly determine the volume and accounting of crushed wood in stocks on the stock exchange of raw materials supplied by road, rail, and water transport. The article considers the possibility of using the developments of the leading Russian developer and manufacturer of electronic solutions for vehicles of the ITELMA Group of Companies for these purposes.

Tradeoffs between Stand Volume and Understory Vegetation Diversity in Quercus wutaishanica Forests under Climate Change

Natural forests play a crucial role in providing various ecosystem services, including timber production and biodiversity conservation. However, climate change and anthropogenic factors pose a severe threat to competing forest ecosystem services functions. Therefore, to optimize and sustainably utilize competing forest services, tradeoffs are often necessary. This study was conducted in Northwest China to explore tradeoffs aimed at improving the quality of Quercus wutaishanica Mayr natural forests under climate change conditions, focusing on stand volume, timber production, and understory vegetation diversity conservation. Data from 77 field surveys were used to construct a coupled model for stand growth, stand structure, and site conditions. Changes in understory vegetation species number (UVSN) with crown cover were quantified. These models and relationships can be used as tools to estimate tradeoffs. As stand density increased, single-tree volume decreased, whereas timber volume increased. UVSN increased and then decreased with increasing crown cover and was able to maintain a relative maximum at 0.5–0.65. Under the current climatic conditions, the optimum stand densities corresponding to 30, 40, 50, and 60 years were 1390, 1153, 1042, and 871 trees/ha, respectively, to maintain a high UVSN and adequate stand volume. When mean annual temperature rose, stand densities could be reduced to maintain high-quality timber. Although only two major services were considered, the tradeoffs presented in this study can inform future research to improve the quality of natural forests.

Economic evaluation of reopening a dormant tree improvement programme: a case study with Scots pine in Scotland

Abstract The deployment of improved forest reproductive material (FRM) selected to yield greater timber volume and quality than unimproved material could help to maintain productive, sustainable, and resilient forests and increase resistance to abiotic and biotic threats under extreme climate change events. In Scotland, Scots pine (Pinus sylvestris L.) is a productive species that aligns with these objectives. However, confidence in Scots pine has been low in recent years due to damage caused by the needle blight Dothistroma septosporum. Recent provenance/progeny trials using native Scots pine material from the Caledonian pine woods indicate a favourable genetic correlation between growth and resistance to D. septosporum, suggesting that simultaneous improvements are possible. The Scots pine breeding programme in Scotland was closed in 2002. Here, we present an economic case for reopening the breeding programme to further improve Scots pine FRM. Specifically, we evaluate the costs and potential benefits of supporting a new programme. We conduct an analysis using three improvement scenarios using a Faustmann formula (amended with thinnings) to maximize the land expectation value. Our results indicate that further improvement of Scots pine FRM would be cost-effective, outperforming the current Scots pine timber production and financial outcomes. The analysis shows that the Central scenario’s land expectation value rises by £883 ha−1 compared to the baseline of £79 ha−1, assuming a 3.5% interest rate. We employed both annuity calculations and a break-even analysis to show improved FRM could maintain a breeding programme investment of £3.5 million per year over a 30-year period with a break-even cost threshold increase of ~52% for purchasing improved planting materials from £0.33 to £0.50 per seedling. In conclusion, the study provides economic evidence of the commercial benefits for reopening the Scots pine breeding programme to increase timber production and financial returns.

Planning cost-effective operational forest inventories.

We address a Bayesian two-stage decision problem in operational forestry where the inner stage considers scheduling the harvesting to fulfill demand targets and the outer stage considers selecting the accuracy of pre-harvest inventories that are used to estimate the timber volumes of the forest tracts. The higher accuracy of the inventory enables better scheduling decisions but also implies higher costs. We focus on the outer stage, which we formulate as a maximization of the posterior value of the inventory decision under a budget constraint. The posterior value depends on the solution to the inner stage problem and its computation is analytically intractable, featuring an NP-hard binary optimization problem within a high-dimensional integral. In particular, the binary optimization problem is a special case of a generalized quadratic assignment problem. We present a practical method that solves the outer stage problem with an approximation which combines Monte Carlo sampling with a greedy, randomized method for the binary optimization problem. We derive inventory decisions for a dataset of 100 Swedish forest tracts across a range of inventory budgets and estimate the value of the information to be obtained.

Territorial planning support tool for sustainable forest management in the Amazon

In forest management, it is crucial to ensure process efficiency to maintain economic viability, especially in native forests where timber volume varies due to the uneven distribution of commercially valuable species. This variability poses a challenge for harvest planning, as the inherent heterogeneity of these forests often results in inconsistent productivity. This study employs the SOTER-PA system, an algorithm-based tool utilizing a minimalist tabu search, to achieve a more homogeneous territorial planning structure for better utilization of natural resources and increased economic returns from forestry activities. The study area is the Tapajós National Forest in the state of Pará, with a forest inventory database covering 2,218.7 hectares and 28,369 trees across 93 species. After applying exclusion criteria and data processing, 8,644 trees were deemed suitable for harvest. The tests suggested a new organization of Work Units, enabling a more balanced income distribution among them, and delineating the areas to be exploited in each cutting cycle. The results show that SOTER-PA not only improves the equitable distribution of natural resources but also enhances economic productivity. This improvement is attributed to the more homogeneous and optimized distribution of high-value species like red cedar and purpleheart. Furthermore, when comparing the SOTER-PA generated parcels with conventional management, the parcels created by SOTER-PA were more homogeneous, with better productivity quality and lower standard deviation, indicating greater uniformity. Thus, the use of SOTER-PA proves to be an efficient alternative for optimizing sustainable forest management planning, offering a more effective method for sustainable territorial planning in native forests, providing both economic and environmental benefits.

Study of the Spatial Distribution of the Bark Beetle in the Ejido Tixtlancingo

The spatial distribution of Dendroctonus frontalis Zimmermann, 1868, and Dendroctonus mexicanus Hopkins, 1905, was determined from 2020 to 2021 in the Tixtlancingo ejido. The information came from two surveys because, despite the abundant forested areas in this geographical area of the state of Guerrero, Mexico, economic resources for pest biomonitoring are limited. However, it was possible to identify the presence of 76 outbreaks affecting 1117.697 hectares and 95,078 trees, totaling 14,223.8 m3 of standing timber volume. In 2020, 28 outbreaks were reported, with the eastern spatial distribution showing the most damage from bark beetles, particularly in outbreaks 7 and 14 of the surveyed area. The most affected conifers were Pinus maximinoi H. E. Moore (44.71%), Pinus oocarpa Schiede ex Schltdl. (39.93%), and Pinus pseudostrobus Lindl. (15.36%). The affected timber volume was observed in diameter categories of 30 cm for the three pine species, with infestation of 90,549 trees (13,497.6 m3 t.t.v. (total tree volume)) across 1057.64 hectares. In 2021, 48 outbreaks were recorded, with the northeastern and southern parts of the surveyed area showing the most damage from the bark beetle. The trees most affected by the bark beetle were P. oocarpa (59.17%), P. maximinoi (33.94%), and P. pseudostrobus (6.89%). It was observed that the affected volume occurred in trees with diameter categories of 50 cm for the three pine species, affecting 4529 trees (726.214 m3 t.t.v.) distributed over 60.06 hectares. The contribution of this work lies in establishing a baseline for monitoring damage caused by this beetle, which affects forest resources and diminishes the possibility of maintaining carbon capture areas in the medium and long term, thus impacting the Sustainable Development Goals (SDGs) of the 2030 agenda, specifically Goals 11, 13, and 15.

Birch distribution and changes in stand structure in Sweden’s young forests

ABSTRACT Silver birch (Betula pendula Roth) and downy birch (Betula pubescens Ehrh.) are the two most common broadleaf species in Sweden, together making up approximately 12% of the standing timber volume. The two birch species are usually not distinguished in practice, although they tend to differ in terms of volume production, timber quality, and site preferences. To map the proportion of the two birch species in Sweden’s young forests, we used survey data from 123 stands 6–7 years after clearfelling, and data from Sweden’s meteorological and hydrological institute. We also examined Sweden’s young forests in terms of area, volume, and stem density between 1983 and 2021, using national forest inventory data. Proportions of the two birch species varied significantly across Sweden, and the average temperature sum over the first five years after clearfelling explained 72% of the variation. There was no significant change in area of forest classified as young forest in Sweden, over the last four decades, although there was a significant increase in volume and stem density in Sweden’s young forests, with birch making up most of the increase in stem numbers.

Growth dynamics of an Amazonian forest: Effects of reduced impact logging and recurring atypical climate events during a 20-year study

Although forest management with reduced impact logging (RIL) practices is regarded as a way to generate income from tropical forests without losing their overall conservation values, the behavior of forests following logging is a topic that has been little studied in the southwestern Brazilian Amazon (SWA), where the predominant forest type is open with low density of commercial timber species. This study examined the growth dynamics of a logged forest in the SWA through monitoring of permanent sample plots (PSP) over twenty years post logging. Following logging, the forest fully recovered its original tree density (439. ha−1) and aboveground biomass (AGB) stocks (188.4 Mg. ha−1) but did not recover extracted timber volume in the commercial size class (DBH > 50 cm, 28 m3. ha−1 before logging and 22.6 m3. ha−1 in 2022). Tree growth, recruitment and mortality rates presented a high fluctuation during the monitoring period, increasing immediately after logging (0.43 cm. yr.−1, 4.1 % and 4.7 % respectively), declining five years after, (0.25 cm. yr.−1, 0.7 % and 1.5 % respectively) and presenting a new peak sixteen years after logging (0.35 cm. yr.−1, 3.9 % and 7.4 % respectively) which persisted to the end of the study period. Consequently, forest turnover was very high, with stand half-life and doubling life of 29.6 and 27.2 years, respectively. The results show that in terms of forest dynamics and production, the behavior of logged forests was also affected by atypical climate events, such as recurring droughts across Amazonia. Consequently, in the forest type studied, and under the prescribed logging cycle of 25 years, RIL alone was not sufficient to guarantee the sustainability of long-term production of the main timber species harvested. Following the current growth trend (0.46 m3. ha−1. yr.−1 for trees above 10 cm DBH and 0.22 m3. ha−1. yr.−1 for trees above 50 cm DBH) the time to recover the total commercial volume and commercial volume for trees above 10 cm DBH and above 50 cm DBH would be 34 and 45 years respectively. Our findings suggest the need for adoption of silvicultural treatments to increase forest productivity in areas under RIL in SWA.

Integrating personal laser scanning with uncrewed aerial vehicle-based photogrammetry or laser scanning for accurate stem volume estimation in temperate coniferous forests

ABSTRACT An extensive number of trees are surveyed for logging purposes, necessitating efficient and precise logging survey methods. Integrating over- and under-canopy remote sensing, such as personal laser scanning (PLS) with uncrewed aerial vehicle-based laser scanning (ULS) or digital aerial photogrammetry (DAP), is a promising method. In this study, we aimed to estimate stem volume in a 16.89-ha coniferous forest using these techniques at the individual, plot, and stand levels. The root mean square error (RMSE) and relative RMSE (rRMSE) when compared to conventional field surveys of PLS-based volume estimations were 0.14 m3 (21.6%) before and 0.08 m3 (12.3%) after bias correction. When integrating PLS with ULS and DAP, the RMSE and rRMSE values were 0.16 m3 (26.7%) and 0.16 m3 (27.0%), respectively. The F-score for the individual tree detection analysis by ULS and DAP were 0.94 and 0.96, respectively. The RMSE of the estimated volume in the plots was 0.08 m3 for both ULS and DAP. The estimated volumes of timber produced in the stand using the utilization rate overestimated the actual volume by 30.6%, 13.0%, and 17.0%, for PLS, ULS, and DAP, respectively. While the individual stem volume estimation accuracy of ULS and DAP was lower than that of the field survey, at the plot level the results were comparable, with ULS and DAP showing results significantly closer to the actual results than those of PLS at the stand level. This study highlights the potential for integrating PLS with uncrewed aerial vehicle methods for estimating stem and log volumes at the plot and stand levels.

Effects of Illumination Conditions on Individual Tree Height Extraction Using UAV LiDAR: Pilot Study of a Planted Coniferous Stand

Tree height is one of the key dendrometric parameters for indirectly estimating the timber volume or aboveground biomass of a forest. Field measurement is time-consuming and labor-intensive, while unmanned aerial vehicle (UAV)-borne LiDAR is a more efficient tool for acquiring tree heights of large-area forests. Although individual tree heights extracted from point cloud data are of high accuracy, they are still affected by some weather and environment factors. In this study, taking a planted M. glyptostroboides (Metasequoia glyptostroboides Hu & W.C. Cheng) stand as the study object, we preliminarily assessed the effects of various illumination conditions (solar altitude angle and cloud cover) on tree height extraction using UAV LiDAR. The eight point clouds of the target stand were scanned at four time points (sunrise, noon, sunset, and night) in two consecutive days (sunny and overcast), respectively. The point clouds were first classified into ground points and aboveground vegetation points, which accordingly produced digital elevation model (DEM) and digital surface model (DSM). Then, the canopy height model (CHM) was obtained by subtracting DEM from DSM. Subsequently, individual trees were segmented based on the seed points identified by local maxima filtering. Finally, the individual tree heights of sample trees were separately extracted and assessed against the in situ measured values. As results, the R2 and RMSEs of tree heights obtained in the overcast daytime were commonly better than those in the sunny daytime; the R2 and RMSEs at night were superior among all time points, while those at noon were poorest. These indicated that the accuracy of individual tree height extraction had an inverse correlation with the intensity of illumination. To obtain more accurate tree heights for forestry applications, it is best to acquire point cloud data using UAV LiDAR at night, or at least not at noon when the illumination is generally strongest.

Optimal Rotation Age in Fast Growing Plantations: A Dynamical Optimization Problem.

Forest plantations are economically and environmentally relevant, as they play a key role in timber production and carbon capture. It is expected that the future climate change scenario affects forest growth and modify the rotation age for timber production. However, mathematical models on the effect of climate change on the rotation age for timber production remain still limited. We aim to determine the optimal rotation age that maximizes the net economic benefit of timber volume in a negative scenario from the climatic point of view. For this purpose, a bioeconomic optimal control problem was formulated from a system of Ordinary Differential Equations (ODEs) governed by the state variables live biomass volume, intrinsic growth rate, and area affected by fire. Then, four control variables were associated to the system, representing forest management activities, which are felling, thinning, reforestation, and fire prevention. The existence of optimal control solutions was demonstrated, and the solutions of the optimal control problem were also characterized using Pontryagin's Maximum Principle. The solutions of the model were approximated numerically by the Forward-Backward Sweep method. To validate the model, two scenarios were considered: a realistic scenario that represents current forestry activities for the exotic species Pinus radiata D. Don, and a pessimistic scenario, which considers environmental conditions conducive to a higher occurrence of forest fires. The optimal solution that maximizes the net benefit of timber volume consists of a strategy that considers all four control variables simultaneously. For felling and thinning, regardless of the scenario considered, the optimal strategy is to spend on both activities depending on the amount of biomass in the field. Similarly, for reforestation, the optimal strategy is to spend as the forest is harvested. In the case of fire prevention, in the realistic scenario, the optimal strategy consists of reducing the expenses in fire prevention because the incidence of fires is lower, whereas in the pessimistic scenario, the opposite is true. It is concluded that the optimal rotation age that maximizes the net economic benefit of timber volume in P. radiata plantations is 24 and 19 years for the realistic and pessimistic scenarios, respectively. This corroborates that the presence of fires influences the determination of the optimal rotation age, and as a consequence, the net economic benefit.

Stand-level sampling designs for bark stripping caused by red deer (Cervus elaphus L.): simulation studies based on nine fully censused stands

AbstractPrecise assessment of bark stripping damage is of high economic importance, since bark stripping makes wood unusable for saw timber and it is important for compensation payments for game damage. Bark stripping is clustered and decreases with increasing tree diameter, so that common forest inventories, optimized for assessing timber production variables such as standing timber volume, do not provide adequately precise estimates of bark stripping damage. In this study we analysed different sampling designs (random sampling, systematic sampling), tree selection methods (fixed radius plot, angle count sampling) and number of plots and plot sizes (plot radius: 2–20 m; basal area factor: 1–6m2/ha) for bark stripping assessment. The analysis is based on simulation studies in 9 fully censused stands (9026 trees). Simulations were done for actually assessed damage and randomly distributed damage and each scenario was repeated 100 times with different random points or different random grid locations. Systematic sampling was considerably more precise than random sampling in both scenarios. Sampling intensities to attain a standard error of 10% ranged between 12 and 18% dependent on the plot size. For a given sampling intensity, precision increased with decreasing plot size or increasing basal area factor. This implies, however, a large number of plots to be measured, which is expensive, when travel costs are high. Differences between tree selection by fixed radius plots or angle count sampling were minor. For bark stripping damage, we recommend sampling with fixed radius plots with a radius of 4–6 m and the measurement of approximately 230 or 150 plots, respectively.