Research

15 pages, 3213 KiB

Open AccessArticle

Estimation of the Productivity Potential of Mountain Sites (Mixed Beech-Coniferous Stands) in the Romanian Carpathians

by Avram Cicșa, Gheorghe-Marian Tudoran, Maria Boroeanu, Alexandru-Claudiu Dobre and Gheorghe Spârchez

Forests 2021, 12(5), 549; https://doi.org/10.3390/f12050549 - 28 Apr 2021

Cited by 3 | Viewed by 1736

Abstract

Research Highlights: This study highlighted the possibility of estimating the productivity of mountain sites (mixed beech-coniferous stands) based on tree and stand dendrometric characteristics. Background and Objectives: The mountainous region of Romania offers suitable conditions for the formation and development of mixed beech-coniferous [...] Read more.

Research Highlights: This study highlighted the possibility of estimating the productivity of mountain sites (mixed beech-coniferous stands) based on tree and stand dendrometric characteristics. Background and Objectives: The mountainous region of Romania offers suitable conditions for the formation and development of mixed beech-coniferous stands with complex, multi-aged structures. Based on the dendrometric characteristics of the trees, established indicators were used to estimate the productivity of the sites, with other quantitative indicators being proposed to better capture the particularities of mixed multi-aged stands. Materials and Methods: To evaluate the productive potential of the sites, a combined in situ mapping method was applied. Laboratory analyses of soils, and information provided indirectly by indicator plant and tree overstories, led to the characterization of soil types and the identification of forest sites for study. The productivity of the sites was estimated using quantitative indicators established based on the dendrometric characteristics of the trees and stands. Results: Indicators based on stand production and growth are relevant for multi-aged stands of mixed beech-coniferous formation. The ratio between tree volume and the basal area is the result of basal area and height increments, both of which are variable and depend on the quality of the site. Thus, a form height stand can be used as an indicator to characterize the productivity of the site in mixed multi-aged stands. Conclusions: Knowing the ecological specificity of sites in the formation of mixed beech-coniferous forests is a first condition necessary to achieving stable stands that are able to continuously fulfill multiple functions. The favorability of forest sites for a certain assortment of species is a fundamental character of the sites, which is essential for the management of these forest formations. Full article

(This article belongs to the Special Issue Forest and Sustainable Development (9th International Symposium on Forest and Sustainable Development))

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21 pages, 5030 KiB

Open AccessArticle

Estimation of Surface Canopy Water in Pacific Northwest Forests by Fusing Radar, Lidar, and Meteorological Data

by Scott Heffernan and Bogdan M Strimbu

Forests 2021, 12(3), 339; https://doi.org/10.3390/f12030339 - 14 Mar 2021

Cited by 2 | Viewed by 1707

Abstract

Surface Canopy Water (SCW) is the intercepted rain water that resides within the tree canopy and plays a significant role in the hydrological cycle. Challenges arise in measuring SCW in remote areas using traditional ground-based techniques. Remote sensing in the radio [...] Read more.

Surface Canopy Water (SCW) is the intercepted rain water that resides within the tree canopy and plays a significant role in the hydrological cycle. Challenges arise in measuring SCW in remote areas using traditional ground-based techniques. Remote sensing in the radio spectrum has the potential to overcome the challenges where traditional modelling approaches face difficulties. In this study, we aim at estimating the SCW by fusing information extracted from the radar imagery acquired with the Sentinel-1 constellation, aerial laser scanning, and meteorological data. To describe the change of radar backscatter with moisture, we focused on six forest stands in the H.J. Andrews experimental forest in central Oregon, as well as four clear cut areas and one golf course, over the summers of 2015–2017. We found significant relationships when we executed the analysis on radar images in which individual tree crowns were delineated from lidar, as opposed to SCW estimated from individual pixel backscatter. Significant differences occur in the mean backscatter between radar images taken during rain vs. dry periods (no rain for >1 h), but these effects only last for roughly 30 min after the end of a rain event. We developed a predictive model for SCW using the radar images acquired at dawn, and proved the capability of space-based radar systems to provide information for estimation of the canopy moisture under conditions of fresh rainfall during the dry season. Full article

(This article belongs to the Special Issue Forest and Sustainable Development (9th International Symposium on Forest and Sustainable Development))

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20 pages, 19601 KiB

Open AccessArticle

The Effect of LiDAR Sampling Density on DTM Accuracy for Areas with Heavy Forest Cover

by Mihnea Cățeanu and Arcadie Ciubotaru

Forests 2021, 12(3), 265; https://doi.org/10.3390/f12030265 - 25 Feb 2021

Cited by 12 | Viewed by 2218

Abstract

Laser scanning via LiDAR is a powerful technique for collecting data necessary for Digital Terrain Model (DTM) generation, even in densely forested areas. LiDAR observations located at the ground level can be separated from the initial point cloud and used as input for [...] Read more.

Laser scanning via LiDAR is a powerful technique for collecting data necessary for Digital Terrain Model (DTM) generation, even in densely forested areas. LiDAR observations located at the ground level can be separated from the initial point cloud and used as input for the generation of a Digital Terrain Model (DTM) via interpolation. This paper proposes a quantitative analysis of the accuracy of DTMs (and derived slope maps) obtained from LiDAR data and is focused on conditions common to most forestry activities (rough, steep terrain with forest cover). Three interpolation algorithms were tested: Inverse Distance Weighted (IDW), Natural Neighbour (NN) and Thin-Plate Spline (TPS). Research was mainly focused on the issue of point data density. To analyze its impact on the quality of ground surface modelling, the density of the filtered data set was artificially lowered (from 0.89 to 0.09 points/m²) by randomly removing point observations in 10% increments. This provides a comprehensive method of evaluating the impact of LiDAR ground point density on DTM accuracy. While the reduction of point density leads to a less accurate DTM in all cases (as expected), the exact pattern varies by algorithm. The accuracy of the LiDAR-derived DTMs is relatively good even when LiDAR sampling density is reduced to 0.40–0.50 points/m² (50–60 % of the initial point density), as long as a suitable interpolation algorithm is used (as IDW proved to be less resilient to density reductions below approximately 0.60 points/m²). In the case of slope estimation, the pattern is relatively similar, except the difference in accuracy between IDW and the other two algorithms is even more pronounced than in the case of DTM accuracy. Based on this research, we conclude that LiDAR is an adequate method for collecting morphological data necessary for modelling the ground surface, even when the sampling density is significantly reduced. Full article

(This article belongs to the Special Issue Forest and Sustainable Development (9th International Symposium on Forest and Sustainable Development))

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13 pages, 2782 KiB

Open AccessArticle

Tree Shape Variability in a Mixed Oak Forest Using Terrestrial Laser Technology: Implications for Mating System Analysis

by Vlăduț Remus Tomșa, Alexandru Lucian Curtu and Mihai Daniel Niță

Forests 2021, 12(2), 253; https://doi.org/10.3390/f12020253 - 22 Feb 2021

Cited by 3 | Viewed by 2452

Abstract

The accuracy of the description regarding tree architecture is crucial for data processing. LiDAR technology is an efficient solution for capturing the characteristics of individual trees. The aim of the present study was to analyze tree shape variability in a mixed oak forest [...] Read more.

The accuracy of the description regarding tree architecture is crucial for data processing. LiDAR technology is an efficient solution for capturing the characteristics of individual trees. The aim of the present study was to analyze tree shape variability in a mixed oak forest consisting of four European white oak species: Quercus petraea, Q. frainetto, Q. pubescens, and Q. robur. Moreover, we tested for association between tree shape and individual heterozygosity and whether oak trees identified as pollen donors in a previous genetic study have a larger size in terms of crown and trunk characteristics than non-donors. The woody structure of a tree was defined by the quantitative structure model (QSM) providing information about topology (branching structure), geometry, and volume. For extracting the 3D point clouds a high-speed 3D scanner (FARO FocusS 70) was used. The crown variables were strongly correlated to each other, the branch volume being influenced by branch length, maximum branch order, and the number of branches but not influenced by diameter at breast height (DBH), trunk length, trunk volume, or tree height. There was no relationship between the individual heterozygosity based on nuclear microsatellite genetic markers and crown and trunk characteristics, respectively. Branch volume, total area, DBH, trunk volume, and the total volume of tree were significantly larger in pollen donors compared to non-donor Q. petraea trees. Thus, the mean branch volume was more than three times higher. Pollen donors had nearly two and half times larger total area in comparison to non-donor individuals. Our results suggest that a thorough characterization of tree phenotype using terrestrial laser scanning may contribute to a better understanding of mating system patterns in oak forests. Full article

(This article belongs to the Special Issue Forest and Sustainable Development (9th International Symposium on Forest and Sustainable Development))

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17 pages, 4136 KiB

Open AccessArticle

Development of Mathematical Models for the Estimation of Dendrometric Variables Based on Unmanned Aerial Vehicle Optical Data: A Romanian Case Study

by Gheorghe Marian Tudoran, Alexandru Claudiu Dobre, Avram Cicșa and Ionuț Silviu Pascu

Forests 2021, 12(2), 200; https://doi.org/10.3390/f12020200 - 09 Feb 2021

Cited by 2 | Viewed by 2098

Abstract

Research highlights: In this study, the possibility of developing predictive models for both individual trees and forest stands, based on information derived from digital surface models (DSMs), was evaluated. Background and objectives: Unmanned aerial systems (UASs) make it possible to obtain digital images [...] Read more.

Research highlights: In this study, the possibility of developing predictive models for both individual trees and forest stands, based on information derived from digital surface models (DSMs), was evaluated. Background and objectives: Unmanned aerial systems (UASs) make it possible to obtain digital images with increased spectral and spatial resolution at a lower cost. Based on the variables extracted by means of the digital representation of surfaces, we aimed at generating mathematical models that would allow the prediction of the main biometric features of both individual trees and forest stands. Materials and methods: Forest stands are characterized by various structures. As such, measurements may address upper-level trees, but most often are oriented towards those belonging to the mean tree category, randomly selected from those identifiable from digital models. In the case of grouped trees, it is the best practice to measure the projected area of the entire canopy. Tree and stand volumes can be determined using models based on features measured in UAS-derived digital models. For the current study, 170-year-old mixed sessile oak stands were examined. Results: Mathematical models were developed based on variables (i.e., crown diameter and tree height) extracted from digital models. In this way, we obtained results characterized by root mean square error (RMSE) values of 18.37% for crown diameter, 10.95% for tree height, and 8.70% for volume. The simplified process allowed for the estimates of the stand volume using crown diameter or diameter at breast height, producing results with RMSE values of 9%. Conclusions: The accuracy of the evaluation of the main biometric features depends on the structural complexity of the studied plots, and on the quality of the DSM. In turn, this leads to the necessity to parametrize the used models in such a manner that can explain the variation induced by the stand structure. Full article

(This article belongs to the Special Issue Forest and Sustainable Development (9th International Symposium on Forest and Sustainable Development))

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17 pages, 6176 KiB

Open AccessArticle

Estimating Biomass and Carbon Storage by Georgia Forest Types and Species Groups Using the FIA Data Diameters, Basal Areas, Site Indices, and Total Heights

by Chris J. Cieszewski, Michał Zasada, Roger C. Lowe and Shanbin Liu

Forests 2021, 12(2), 141; https://doi.org/10.3390/f12020141 - 26 Jan 2021

Cited by 4 | Viewed by 2408

Abstract

We present here an example of research into methodology of an estimation of carbon and biomass pools in forests using the USDA Forest Service, Forest Inventory and Analysis (FIA), data of the 1989 and 1998 surveys for Georgia forests, as relevant for comparison [...] Read more.

We present here an example of research into methodology of an estimation of carbon and biomass pools in forests using the USDA Forest Service, Forest Inventory and Analysis (FIA), data of the 1989 and 1998 surveys for Georgia forests, as relevant for comparison with other extremely highly-cited estimates of similar, but different, methodologies. Based on the derived estimates, we produce an example map of the biomass density and pools at a sub-county level resolution, which is based on spatially explicit simulations of the potential cover-type polygons implied by the FIA data with approximate plot locations. Our results include estimates of the biomass pools in the belowground biomass in roots, aboveground woody biomass in trees, and the biomass of foliage. We estimated the biomass densities and pools at a tree level using diameters and heights and previously published models, then propagated these results to the plot level using tree expansion factors, and then transformed these estimates to plot-dependent polygons using plot expansion factors. The plot-dependent polygons were spatially simulated using a simplified assumption of homogeneity of conditions surrounding each plot to the extent of the area defined by this plot’s expansion factors. The derived map provides a visual representation of the distribution of forest biomass densities and pools in the state of Georgia with distinctive patterns observed in various areas of urban development, federally owned forests, primary commercial forestland, and other land use areas. Coniferous forests with the highest total biomass density are located mostly in three regions: northern Georgia (Appalachian Highlands), the southern part of Piedmont, and the eastern part of Coastal Plain. Deciduous and mixed forests with the highest biomass density are concentrated mostly in the northern part of the state—especially in the Blue Ridge physiographic province, and in the western part of the East Gulf Coastal Plain. Counties with the highest biomass density were located primarily in the northern part of the state, while counties with the lowest density tended to be located in the Coastal Georgia area. Full article

(This article belongs to the Special Issue Forest and Sustainable Development (9th International Symposium on Forest and Sustainable Development))

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18 pages, 1210 KiB

Open AccessArticle

Analysis of State Forest Institutions in the Republic of Moldova, Using a Causative Model

by Nicolae Talpă, Aureliu Florin Hălălișan and Bogdan Popa

Forests 2021, 12(1), 105; https://doi.org/10.3390/f12010105 - 19 Jan 2021

Cited by 4 | Viewed by 2714

Abstract

With state institutions playing a determinant role and the state owning 86% of the forestland, the forest sector in the Republic of Moldova still strives to adapt to post-communist socio-economic realities. This paper evaluates the performance of forest state institutions in achieving ambitious [...] Read more.

With state institutions playing a determinant role and the state owning 86% of the forestland, the forest sector in the Republic of Moldova still strives to adapt to post-communist socio-economic realities. This paper evaluates the performance of forest state institutions in achieving ambitious policy goals oriented toward sustainable management and enhancing forest protection functions. The performance of the Moldsilva Agency; State Forest Enterprises; and Ministry of Agriculture, Regional Development and Environment were evaluated, using the criteria of the 3L Model. The research combined participatory observations, face-to-face semi-structured interviews and secondary empirical evidence. The results indicate a paternalistic regulatory approach, with state authority institutions giving marginal importance to non-state forests, and low-efficiency state forest management institutions having financial difficulties that threaten the fulfillment of sustainability goals. The Moldsilva Agency has a central role in intra-/inter-sectorial coordination and cooperation. The authorities should seriously consider a more precise formulation of policy goals, with solid budgetary support along with institutional measures aiming at more efficient forest management structures and higher concern for non-state forests and society’s demands. Full article

(This article belongs to the Special Issue Forest and Sustainable Development (9th International Symposium on Forest and Sustainable Development))

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14 pages, 77915 KiB

Open AccessArticle

Economic Valuation of Carbon Storage and Sequestration in Retezat National Park, Romania

by Robert-George Pache, Ioan Vasile Abrudan and Mihai-Daniel Niță

Forests 2021, 12(1), 43; https://doi.org/10.3390/f12010043 - 30 Dec 2020

Cited by 23 | Viewed by 5612

Abstract

Carbon storage and sequestration is one of the most important services provided by forest ecosystems, the most powerful tools for climate change mitigation and adaptation. Its value is not always captured and appreciated at a fair level, with people taking for granted these [...] Read more.

Carbon storage and sequestration is one of the most important services provided by forest ecosystems, the most powerful tools for climate change mitigation and adaptation. Its value is not always captured and appreciated at a fair level, with people taking for granted these benefits provided by the ecosystems. Our first objective was to evaluate the amount of carbon storage and sequestration within a specific area—Retezat National Park (RNP), Romania, in a specific timeframe, using mainly the data from forest management plans. The second objective was to estimate the economic value of the carbon sequestered by the ecosystems within the national park. Based on the carbon market price, we calculated the monetary value of the sequestered carbon. The third objective was to cross-validate the model using mobile terrestrial LiDAR scanner 3D mapping technology in several field plots. Our results reveal comparable stocks of carbon with the ones modelled based on the forest management plans, enabling us to use these plans as an accurate source of information. The present study underlines that the financial effort for the management of the ecosystems which provide these services can be sustained by implementing financial mechanisms aiming to direct ecosystem services values into the management of these ecosystems. Full article

(This article belongs to the Special Issue Forest and Sustainable Development (9th International Symposium on Forest and Sustainable Development))

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14 pages, 2499 KiB

Open AccessArticle

Low Population Differentiation but High Phenotypic Plasticity of European Beech in Germany

by Markus Müller, Tanja Kempen, Reiner Finkeldey and Oliver Gailing

Forests 2020, 11(12), 1354; https://doi.org/10.3390/f11121354 - 18 Dec 2020

Cited by 11 | Viewed by 2458

Abstract

Drought is increasingly impairing the vitality of European beech (Fagus sylvatica L.) in several regions of its distribution range. In times of climate change, adaptive traits such as plant phenology and frost tolerance are also becoming more important. Adaptive patterns of European [...] Read more.

Drought is increasingly impairing the vitality of European beech (Fagus sylvatica L.) in several regions of its distribution range. In times of climate change, adaptive traits such as plant phenology and frost tolerance are also becoming more important. Adaptive patterns of European beech seem to be complex, as contrasting results regarding the relative effect of phenotypic plasticity and genetic variation in trait variation have been reported. Here, we used a large translocation experiment comprising more than 15,500 seedlings in three regions of Germany to investigate local adaptation and phenotypic plasticity in beech. We found low population differentiation regarding plant survival, and plant height increment, but high phenotypic plasticity for these traits. Survival showed a positive correlation with temperature variables and a less pronounced and negative correlation with precipitation-related variables. This suggests a predominant effect of temperature and growing degree days on the survival of beech seedlings under moderate drought stress. The high phenotypic plasticity may help beech to cope with changing environmental conditions, albeit increasing drought stress may make adaptive changes necessary in the long term. Full article

(This article belongs to the Special Issue Forest and Sustainable Development (9th International Symposium on Forest and Sustainable Development))

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13 pages, 2501 KiB

Open AccessArticle

Impact of Algorithm Selection on Modeling Ozone Pollution: A Perspective on Box and Tiao (1975)

by Mihaela Paun, Nevine Gunaime and Bogdan M. Strimbu

Forests 2020, 11(12), 1311; https://doi.org/10.3390/f11121311 - 09 Dec 2020

Cited by 3 | Viewed by 1812

Abstract

Estimation using a suboptimal method can lead to imprecise models, with cascading effects in complex models, such as climate change or pollution. The goal of this study is to compare the solutions supplied by different algorithms used to model ozone pollution. Using Box [...] Read more.

Estimation using a suboptimal method can lead to imprecise models, with cascading effects in complex models, such as climate change or pollution. The goal of this study is to compare the solutions supplied by different algorithms used to model ozone pollution. Using Box and Tiao (1975) study, we have predicted ozone concentration in Los Angeles with an ARIMA and an autoregressive process. We have solved the ARIMA process with three algorithms (i.e., maximum likelihood, like Box and Tiao, conditional least square and unconditional least square) and the autoregressive process with four algorithms (i.e., Yule–Walker, iterative Yule–Walker, maximum likelihood, and unconditional least square). Our study shows that Box and Tiao chose the appropriate algorithm according to the AIC but not according to the mean square error. Furthermore, Yule–Walker, which is the default algorithm in many software, has the least reliable results, suggesting that the method of solving complex models could alter the findings. Finally, the model selection depends on the technical details and on the applicability of the model, as the ARIMA model is suitable from the AIC perspective but an autoregressive model could be preferred from the mean square error viewpoint. Our study shows that time series analysis should consider not only the model shape but also the model estimation, to ensure valid results. Full article

(This article belongs to the Special Issue Forest and Sustainable Development (9th International Symposium on Forest and Sustainable Development))

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17 pages, 2030 KiB

Open AccessArticle

Improving Environmental and Energy Efficiency in Wood Transportation for a Carbon-Neutral Forest Industry

by Teijo Palander, Hanna Haavikko, Emma Kortelainen, Kalle Kärhä and Stelian Alexandru Borz

Forests 2020, 11(11), 1194; https://doi.org/10.3390/f11111194 - 12 Nov 2020

Cited by 27 | Viewed by 3315

Abstract

Wood transportation is an important source of greenhouse gas emissions, which should be considered when the carbon neutrality of the forest industry is of concern. The EU is dedicated to improving technology for a carbon-neutral development. This study investigates carbon neutrality by improving [...] Read more.

Wood transportation is an important source of greenhouse gas emissions, which should be considered when the carbon neutrality of the forest industry is of concern. The EU is dedicated to improving technology for a carbon-neutral development. This study investigates carbon neutrality by improving road freight transportation fleets consisting of various vehicle size combinations. The environmental emission and energy efficiency of a transportation fleet were analyzed in selected wood procurement regions of Stora Enso corporation (Finland). Based on the enterprise resource planning (ERP) data (2018–2020), the environmental emission efficiency increased by 11% via 76 t-vehicles compared 64 t vehicles. The maximum reduction in fuel consumption was 26% for 92 t vehicles, though this was achieved when operations were fully adjusted to the maximum weight limit. The wood-based energy efficiency measure (wood energy/transport energy) was a useful development indicator. It showed that the adapted fleets of transportation companies support a positive development for a carbon-neutral forestry. In respect to the current legal fleet (64, 68 and 76 t), the use of 76 t vehicles increased energy efficiency most effectively, by 50%, compared to 64 t vehicles in the best region. Currently, transportation service providers and their clients are using ERP information to tailor their energy efficiency metric and to implement them locally in the transportation monitoring systems. A three-year sensitivity analysis demonstrates that the technological development of management tools to improve transportation efficiency is essential for larger and heavier vehicle utilization. In the future, the whole wood supply chain from forest to factory will also be optimized with respect to energy efficiency criterion to ensure a low-carbon forest industry. Full article

(This article belongs to the Special Issue Forest and Sustainable Development (9th International Symposium on Forest and Sustainable Development))

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