Forests

23 pages, 4158 KiB

Open AccessArticle

Assessing Habitat Suitability of Parasitic Plant Cistanche deserticola in Northwest China under Future Climate Scenarios

by Jing Liu, Yang Yang, Haiyan Wei, Quanzhong Zhang, Xuhui Zhang, Xiaoyan Zhang and Wei Gu

Forests 2019, 10(9), 823; https://doi.org/10.3390/f10090823 - 19 Sep 2019

Cited by 20 | Viewed by 3920

Abstract

Cistanche deserticola Ma, a perennial parasitic herb of family Orobanchaceae, is mainly parasitic on the roots of the Haloxylon ammodendron Bunge. In view of this special parasitic relationship, we applied random forest (RF) model to forecast potential geographic distribution, and developed a comprehensive [...] Read more.

Cistanche deserticola Ma, a perennial parasitic herb of family Orobanchaceae, is mainly parasitic on the roots of the Haloxylon ammodendron Bunge. In view of this special parasitic relationship, we applied random forest (RF) model to forecast potential geographic distribution, and developed a comprehensive habitat suitability model by integrating bioclimatic and soil factors to assess the suitable distribution of C. deserticola and H. ammodendron across China in 2050s and 2070s under RCP2.6, RCP4.5, and RCP8.5, respectively. We modeled the core potential geographic distribution of C. deserticola by overlaying the distribution of these two species, and analyzed the spatial distribution pattern and migration trend of C. deserticola by using the standard deviational ellipse. In addition, we evaluated the accuracy of RF model through three evaluation indexes, and analyzed the dominant climate factors. The results showed that the core potential distribution areas of C. deserticola are distributed in the Xinjiang Uygur Autonomous Region, the junction of Shaanxi–Gansu–Ningxia provinces, and the Inner Mongolia Autonomous Region. The spatial dispersion would intensify with the increasing of emission scenarios, and the geographical habitat is moving towards higher latitude. Among the three evaluation indexes, the area under the ROC curve (AUC) and True Skill Statistic (TSS) have better assessment results. The main bioclimatic factors affecting the distribution are min temperature of coldest month (Bio6), annual precipitation (Bio12), precipitation of wettest month (Bio13), precipitation of wettest quarter (Bio16), and precipitation of warmest quarter (Bio18), among which the importance of precipitation factors is greater than temperature factors. More importantly, the results of this study could provide some guidance for the improvement of desert forest system, the protection of endangered species and the further improvement of the ecological environment. Full article

(This article belongs to the Special Issue Impact of Land Use Change on Forest Biodiversity)

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10 pages, 1135 KiB

Open AccessArticle

Uncertainty Simulation of Wood Chipping Operation for Bioenergy Based on Queuing Theory

by Mika Yoshida and Katsuhiko Takata

Forests 2019, 10(9), 822; https://doi.org/10.3390/f10090822 - 19 Sep 2019

Cited by 3 | Viewed by 3224

Abstract

Managing uncertainty is the way to secure stability of the supply chain. Uncertainty within chipping operation and chip transportation causes production loss. In the wood chip supply chain for bioenergy, operational uncertainty mainly appears in the moisture content of the material, chipping productivity, [...] Read more.

Managing uncertainty is the way to secure stability of the supply chain. Uncertainty within chipping operation and chip transportation causes production loss. In the wood chip supply chain for bioenergy, operational uncertainty mainly appears in the moisture content of the material, chipping productivity, and the interval of truck arrival. This study theoretically quantified the loss in wood chip production by applying queuing theory and stochastic modelling. As well as the loss in production, the inefficiency was identified as the idling time of chipper and the queuing time of trucks. The aim of this study is to quantify the influence of three uncertainties on wood chip production. This study simulated the daily chip production using a mobile chipper by applying queuing theory and stochastic modelling of three uncertainties. The result was compared with the result of deterministic simulation which did not consider uncertainty. Uncertainty reduced the production by 14% to 27% compared to the production of deterministic simulation. There were trucks scheduled but not used. The cases using small trucks show the largest daily production amount, but their lead time was the longest. The large truck was sensitive to the moisture content of material because of the balance between payload and volumetric capacity. This simulation method can present a possible loss in production amount and enables to evaluate some ways for the loss compensation quantitatively such as outsourcing or storing buffer. For further development, the data about the interval of truck arrival should be collected from fields and analyzed. We must include the other uncertainties causing technical and operator delays. Full article

(This article belongs to the Special Issue Supply Chain Optimization for Biomass and Biofuels)

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13 pages, 32911 KiB

Open AccessArticle

Spatial Genetic Patterns and Distribution Dynamics of the Rare Oak Quercus chungii: Implications for Biodiversity Conservation in Southeast China

by Xiao-Long Jiang, Gangbiao Xu and Min Deng

Forests 2019, 10(9), 821; https://doi.org/10.3390/f10090821 - 19 Sep 2019

Cited by 14 | Viewed by 3395

Abstract

A rapidly changing climate and frequent human activity influences the distribution and community structure of forests. Increasing our knowledge about the genetic diversity and distribution patterns of trees is helpful for forest conservation and management. In this study, nSSRs (nuclear simple sequence repeats) [...] Read more.

A rapidly changing climate and frequent human activity influences the distribution and community structure of forests. Increasing our knowledge about the genetic diversity and distribution patterns of trees is helpful for forest conservation and management. In this study, nSSRs (nuclear simple sequence repeats) were integrated with a species distribution model (SDM) to investigate the spatial genetic patterns and distribution dynamics of Quercus chungii F.P.Metcalf, a rare oak in the subtropics of southeast China. A total of 188 individuals from 11 populations distributed across the natural range of Q. chungii were genotyped using nine nSSRs. The STRUCTURE analysis indicated that genetic admixture was present in all populations, but the population genetic variation and genetic differentiation were related to their geographical distributions. The SDM result indicated that Q. chungii retreated to the Nanling Mountains and adjacent areas during the Last Glacial Maximum (LGM) period, which corresponds to higher genetic diversity for populations in this region. Landscape genetic analysis showed that the Nanling Mountains served as a corridor for organism dispersal at the glacial and interglacial periods within the Quaternary. Based on these results, we propose that establishing nature reserves to protect the ecological corridor across the Nanling Mountains is necessary for the conservation of regional species genetic diversity, as well as the ecosystem of evergreen broadleaved forests in southern China. The study combines species distribution models and genetic diversity to provide new insight into biodiversity conservation and forest management under future climate change. Full article

(This article belongs to the Section Forest Ecology and Management)

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15 pages, 3190 KiB

Open AccessArticle

Hedonic Analysis of Forest Pest Invasion: the Case of Emerald Ash Borer

by Xiaoshu Li, Thomas P. Holmes, Kevin J. Boyle, Ellen V. Crocker and C. Dana Nelson

Forests 2019, 10(9), 820; https://doi.org/10.3390/f10090820 - 19 Sep 2019

Cited by 9 | Viewed by 3829

Abstract

The emerald ash borer (EAB) was first detected in North America in 2002, and since its introduction, this invasive pest has killed millions of ash trees. While EAB kills native North American ash trees in all settings, its impacts have been especially large [...] Read more.

The emerald ash borer (EAB) was first detected in North America in 2002, and since its introduction, this invasive pest has killed millions of ash trees. While EAB kills native North American ash trees in all settings, its impacts have been especially large in urban areas where ash has been a dominant street tree, especially in residential areas. While some management costs, such as insecticide treatment, tree removal, or tree replacement, are relatively straightforward to compute, the impact that EAB has had on residential property values is less clear. To better understand the economic cost of EAB in urban settings, we conducted a hedonic property value analysis to evaluate the impact of ash tree damages due to EAB infestation on housing sales prices. This study was conducted in the city of Milwaukee, Wisconsin, which had high stocking levels of ash trees prior to EAB’s arrival. The objectives of the study are to investigate: (1) how EAB-infested ash trees affect property values; (2) whether the benefits from healthy ash trees to property value change after arrival of EAB; and (3) whether healthy ash trees located within infested neighborhoods provide the same benefits as the healthy ash trees located outside of infested neighborhoods. In general, our results show that the EAB outbreak has had a negative impact on home values for properties located in close proximity to the ash tree component of the urban forest. This result holds true for neighborhoods where EAB does not yet pose an imminent threat, and is amplified for neighborhoods where EAB has been detected. Our results highlight the early stages of a dynamic economic process that impacts urban residential property owners subject to the risk of EAB or other tree pests and diseases. In general, we find that forward-looking behavior of residential property owners is capitalized into property values during the process of forest pest infestation. Full article

(This article belongs to the Special Issue Understanding Forest Health under Increasing Climate and Trade Challenges: Social System Considerations)

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26 pages, 6732 KiB

Open AccessArticle

Prediction of Aboveground Biomass from Low-Density LiDAR Data: Validation over P. radiata Data from a Region North of Spain

by Leyre-Torre Tojal, Aitor Bastarrika, Brian Barrett, Javier Maria Sanchez Espeso, Jose Manuel Lopez-Guede and Manuel Graña

Forests 2019, 10(9), 819; https://doi.org/10.3390/f10090819 - 19 Sep 2019

Cited by 13 | Viewed by 3793

Abstract

Estimation of forestry aboveground biomass (AGB) by means of aerial Light Detection and Ranging (LiDAR) data uses high-density point sampling data obtained in dedicated flights, which are often too costly for available research budgets. In this paper we exploit already existing public low-density [...] Read more.

Estimation of forestry aboveground biomass (AGB) by means of aerial Light Detection and Ranging (LiDAR) data uses high-density point sampling data obtained in dedicated flights, which are often too costly for available research budgets. In this paper we exploit already existing public low-density LiDAR data obtained for other purposes, such as cartography. The challenge is to show that such low-density data allows accurate biomass estimation. We demonstrate the approach on data available from plantations of Pinus radiata in the Arratia-Nervión region, located in Biscay province located in the North of Spain. We use public data gathered from the low-density (0.5 pulse/m²) LiDAR flight conducted by the Basque Government in 2012 for cartographic production. We propose a linear regression model based on explanatory variables obtained from the LiDAR point cloud data. We calibrate the model using field data from the Fourth National Forest Inventory (NFI4), including the selection of the optimal model variables. The results revealed that the best model depends on two variables extracted from LiDAR data: One directly related with tree height and a second parameter with the canopy density. The model explained 80% of its variability with a standard error of 0.25 ton/ha in logarithmic units. We validate the predictions against the biomass measurements provided by the government institutions, obtaining a difference of 8%. The proposed approach would allow the exploitation of the periodic available low-density LiDAR data, collected with territorial and cartographic purposes, for a more frequent and less expensive control of the forestry biomass. Full article

(This article belongs to the Special Issue Using LiDAR and Optical Imagery to Map Forest Vegetation for Assessing Wildlife Habitat)

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17 pages, 9506 KiB

Open AccessArticle

Mapping Tree Species Composition Using OHS-1 Hyperspectral Data and Deep Learning Algorithms in Changbai Mountains, Northeast China

by Yanbiao Xi, Chunying Ren, Zongming Wang, Shiqing Wei, Jialing Bai, Bai Zhang, Hengxing Xiang and Lin Chen

Forests 2019, 10(9), 818; https://doi.org/10.3390/f10090818 - 19 Sep 2019

Cited by 27 | Viewed by 4504

Abstract

The accurate characterization of tree species distribution in forest areas can help significantly reduce uncertainties in the estimation of ecosystem parameters and forest resources. Deep learning algorithms have become a hot topic in recent years, but they have so far not been applied [...] Read more.

The accurate characterization of tree species distribution in forest areas can help significantly reduce uncertainties in the estimation of ecosystem parameters and forest resources. Deep learning algorithms have become a hot topic in recent years, but they have so far not been applied to tree species classification. In this study, one-dimensional convolutional neural network (Conv1D), a popular deep learning algorithm, was proposed to automatically identify tree species using OHS-1 hyperspectral images. Additionally, the random forest (RF) classifier was applied to compare to the algorithm of deep learning. Based on our experiments, we drew three main conclusions: First, the OHS-1 hyperspectral images used in this study have high spatial resolution (10 m), which reduces the influence of mixed pixel effect and greatly improves the classification accuracy. Second, limited by the amount of sample data, Conv1D-based classifier does not need too many layers to achieve high classification accuracy. In addition, the size of the convolution kernel has a great influence on the classification accuracy. Finally, the accuracy of Conv1D (85.04%) is higher than that of RF model (80.61%). Especially for broadleaf species with similar spectral characteristics, such as Manchurian walnut and aspen, the accuracy of Conv1D-based classifier is significantly higher than RF classifier (87.15% and 71.77%, respectively). Thus, the Conv1D-based deep learning framework combined with hyperspectral imagery can efficiently improve the accuracy of tree species classification and has great application prospects in the future. Full article

(This article belongs to the Section Forest Inventory, Modeling and Remote Sensing)

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17 pages, 11421 KiB

Open AccessArticle

Regional and Local Moisture Gradients Drive the Resistance to and Recovery from Drought of Picea crassifolia Kom. in the Qilian Mountains, Northwest China

by Lingnan Zhang, Hui Li, Yilin Ran, Keyi Wang, Xiaomin Zeng and Xiaohong Liu

Forests 2019, 10(9), 817; https://doi.org/10.3390/f10090817 - 19 Sep 2019

Cited by 9 | Viewed by 2555

Abstract

Increasing evidence suggests that extreme droughts cause more frequent tree growth reduction. To understand the consequences of these droughts better, this study used tree-ring cores from nine sites to investigate how moisture and altitudinal gradients affect the radial growth of Picea crassifolia Kom., [...] Read more.

Increasing evidence suggests that extreme droughts cause more frequent tree growth reduction. To understand the consequences of these droughts better, this study used tree-ring cores from nine sites to investigate how moisture and altitudinal gradients affect the radial growth of Picea crassifolia Kom., a common species in the Qilian Mountains in northwest China. The total annual precipitation and mean annual temperature in the eastern region were higher than those in the western region of the Qilian Mountains. The trees in the eastern region showed stronger resistance to drought than those in the west, as they had a smaller difference in radial growth between drought disturbance and pre-drought disturbance. At the same time, the trees in the east showed weaker ability to recover from drought, as they had a subtle difference in radial growth between post-drought disturbance and drought disturbance. Furthermore, the trees in the east also showed weaker relative resilience to drought, as they had a small difference in radial growth between post-drought and drought disturbance weighted by growth in pre-drought disturbance. For trees below 3000 m a.s.l., trees with high resistance capacity usually had low recovery capacity and low relative resilience capacity. Trees at higher altitudes also showed stronger resistance to drought and weaker ability to recover from drought after a drought event than those at lower altitudes in the middle of the Qilian Mountains. Trees at lower altitudes in the middle of the Qilian Mountains had more difficulties recovering from more severe and longer drought events. In the context of global warming, trees in the western region and at lower altitudes should be given special attention and protection in forest management to enhance their resistance to extreme droughts. Full article

(This article belongs to the Section Forest Ecophysiology and Biology)

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15 pages, 2656 KiB

Open AccessArticle

Relationship between Pine Wilt Disease Outbreaks and Climatic Variables in the Three Gorges Reservoir Region

by Ruihe Gao, Zhuang Wang, Haixiang Wang, Yanping Hao and Juan Shi

Forests 2019, 10(9), 816; https://doi.org/10.3390/f10090816 - 19 Sep 2019

Cited by 24 | Viewed by 3282

Abstract

Outbreaks of pine wilt disease (PWD, caused by the pinewood nematode Bursaphelenchus xylophilus), have caused mass mortality of the genus Pinus in Eurasia. Climate change may greatly influence the distribution and population dynamics of longhorn beetles of the genus Monochamus (the main [...] Read more.

Outbreaks of pine wilt disease (PWD, caused by the pinewood nematode Bursaphelenchus xylophilus), have caused mass mortality of the genus Pinus in Eurasia. Climate change may greatly influence the distribution and population dynamics of longhorn beetles of the genus Monochamus (the main vector of B. xylophilus), the survival and development of B. xylophilus, and the resistance of pines. The aim of this study was to investigate the effect of climatic variables associated with extensive PWD outbreaks in Masson pine (Pinus massoniana Lamb.) forest across the eastern part of the Three Gorges Reservoir region. Since its discovery in 2006, the most serious PWD outbreak occurred from 2014 to 2018; the most striking characteristic of this outbreak is the consistent increase in Masson pine mortality and extent of the affected areas. Moreover, 28 out of 46 PWD biological relevant climatic variables were selected and used for redundancy analysis. The ordination biplots reflect the complicated quantitative relationship between the PWD epidemic variables and the biologically relevant climatic variables of temperature, precipitation, relative humidity, and wind speed. The results will be useful for understanding the role climatic variables play in PWD outbreaks, for predicting the spread and pattern of PWD outbreaks, and for the advance preparation of management strategies with the purpose of preventing future PWD outbreaks. Full article

(This article belongs to the Special Issue Forest Health: Fungal and Insect Ecology)

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12 pages, 2749 KiB

Open AccessArticle

UAV-Based High-Throughput Approach for Fast Growing Cunninghamia lanceolata (Lamb.) Cultivar Screening by Machine Learning

by Xiaodan Zou, Anjie Liang, Bizhi Wu, Jun Su, Renhua Zheng and Jian Li

Forests 2019, 10(9), 815; https://doi.org/10.3390/f10090815 - 19 Sep 2019

Cited by 8 | Viewed by 3057

Abstract

Obtaining accurate measurements of tree height and diameter at breast height (DBH) in forests to evaluate the growth rate of cultivars is still a significant challenge, even when using light detection and ranging (LiDAR) and three-dimensional (3-D) modeling. As an alternative, we provide [...] Read more.

Obtaining accurate measurements of tree height and diameter at breast height (DBH) in forests to evaluate the growth rate of cultivars is still a significant challenge, even when using light detection and ranging (LiDAR) and three-dimensional (3-D) modeling. As an alternative, we provide a novel high-throughput strategy for predicting the biomass of forests in the field by vegetation indices. This study proposes an integrated pipeline methodology to measure the biomass of different tree cultivars in plantation forests with high crown density, which combines unmanned aerial vehicles (UAVs), hyperspectral image sensors, and data processing algorithms using machine learning. Using a planation of Cunninghamia lanceolate, which is commonly known as Chinese fir, in Fujian, China, images were collected while using a hyperspectral camera. Vegetation indices and modeling were processed in Python using decision trees, random forests, support vector machine, and eXtreme Gradient Boosting (XGBoost) third-party libraries. The tree height and DBH of 2880 samples were manually measured and clustered into three groups—“Fast”, “median”, and “normal” growth groups—and 19 vegetation indices from 12,000 pixels were abstracted as the input of features for the modeling. After modeling and cross-validation, the classifier that was generated by random forests had the best prediction accuracy when compared to other algorithms (75%). This framework can be applied to other tree species to make management and business decisions. Full article

(This article belongs to the Section Forest Inventory, Modeling and Remote Sensing)

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26 pages, 4494 KiB

Open AccessArticle

Temporal Evolution of Carbon Stocks, Fluxes and Carbon Balance in Pedunculate Oak Chronosequence under Close-To-Nature Forest Management

by Maša Zorana Ostrogović Sever, Giorgio Alberti, Gemini Delle Vedove and Hrvoje Marjanović

Forests 2019, 10(9), 814; https://doi.org/10.3390/f10090814 - 18 Sep 2019

Cited by 10 | Viewed by 4289

Abstract

Under current environmental changes, forest management is challenged to foster contrasting benefits from forests, such as continuous wood supply while preserving biomass production, biodiversity conservation, and contribution to climate change mitigation through atmospheric carbon sequestration. Although being found as globally important, estimates of [...] Read more.

Under current environmental changes, forest management is challenged to foster contrasting benefits from forests, such as continuous wood supply while preserving biomass production, biodiversity conservation, and contribution to climate change mitigation through atmospheric carbon sequestration. Although being found as globally important, estimates of long-term forest C balance are still highly uncertain. In this context, the chronosequence experiments (space-for-time substitution) might fill this gap in even-aged forests, as they represent an approach that enables the assessment of forest net C balance in the long term. In this research, we explored the dynamics of C stocks and fluxes in different forest pools throughout the rotation period (140 years) of a Pedunculate oak (Quercus robur L.) forest in Croatia. For this purpose, we selected a chronosequence that was made up of seven forest stands with different age (5, 13, 38, 53, 68, 108, and 138 years). To address the issues of uncertainty in C balance estimates, we compared net ecosystem carbon balance (NECB) estimated while using two different approaches, which we name pool-change (from C stocks) approach and component-flux (from C fluxes) approach. Overall, the pool-change approach showed higher NECB estimate, with the greatest difference being observed in younger stands (<50 years). Component-flux approach showed significantly higher uncertainty. Throughout the rotation period, managed pedunculate oak stands become a C sink early in their development phase, between the age of 13 and 35 years according to pool-change and component-flux approach, respectively. During the 140 years, oak forest provided 187.2 Mg C ha⁻¹ (604 m³ ha⁻¹) through thinnings and 147.9 Mg C ha⁻¹ (477 m³ ha⁻¹) in the final cut, while preserving, on average, 88.9 Mg C ha⁻¹ in mineral soil down to 40 cm, 18.2 Mg C ha⁻¹ in dead wood, and 6.0 Mg C ha⁻¹ in the forest floor. Soil C stocks in our chronosequence did not show any age-related trend, indicating that current management practice has no negative effect on soil C stocks. Finally, under current close-to-nature forest management, Pedunculate oak forest showed to be sustainable in providing both economic and ecological ecosystem services. Full article

(This article belongs to the Collection Forests Carbon Fluxes and Sequestration)

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13 pages, 1442 KiB

Open AccessArticle

Non-Timber Forest Products Collection Affects Education of Children in Forest Proximate Communities in Northeastern Pakistan

by Muhammad Zubair, Akash Jamil, Martin Lukac and Syed Amir Manzoor

Forests 2019, 10(9), 813; https://doi.org/10.3390/f10090813 - 18 Sep 2019

Cited by 6 | Viewed by 4427

Abstract

Non-timber forest products (NTFPs) are crucial in driving the economy of communities living inside or around forests. The scarcity of business and employment opportunities often push the forest proximate communities to tap a range of NTFPs for earning their livelihoods. In many forest-based [...] Read more.

Non-timber forest products (NTFPs) are crucial in driving the economy of communities living inside or around forests. The scarcity of business and employment opportunities often push the forest proximate communities to tap a range of NTFPs for earning their livelihoods. In many forest-based communities around the world, children are actively involved in NTFPs collection, which is likely to affect the socioeconomic paradigms of these children. We aim to investigate how the NTFP collection venture affects the education of the children involved in the forest proximate communities of Azad Jammu and Kashmir (AJK), Pakistan. A stratified sampling followed by a series of focus group discussions and one-to-one interviews were carried out to collect information on collection behaviour, patterns, income generation, and other socioeconomic variables. We used a binary logistic regression model to explain children’s state of attending schools using a range of socioeconomic variables. The empirical evidence showed that 42% of the NTFP-collecting children were not going to school, and nearly two-thirds were working in unfavourable working environments. The regression model showed that the role and behaviour of contractors, along with factors like household conditions, were important factors in employing children for long working hours. The study has implications for reforming policies regarding the nexus of income generation and education in the forest-based communities. Full article

(This article belongs to the Special Issue Non-Timber Forest Products and Bioeconomy: Management, Value Chains, Challenges and Opportunities)

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13 pages, 2287 KiB

Open AccessArticle

Fire Scars Negatively Affect Hydraulic Conductivity in White Oak (Quercus alba)

by Justin R. Dee, Michael C. Stambaugh, Kevin T. Smith and Daniel C. Dey

Forests 2019, 10(9), 812; https://doi.org/10.3390/f10090812 - 18 Sep 2019

Cited by 1 | Viewed by 2844

Abstract

Fire management is increasingly used to manage forest stand structure and dynamics. Relatively intense fires can injure the tree stem and induce fire scar formation, affecting subsequent tree growth and wood quality. Here, we consider the physiological effects of fire scarring in white [...] Read more.

Fire management is increasingly used to manage forest stand structure and dynamics. Relatively intense fires can injure the tree stem and induce fire scar formation, affecting subsequent tree growth and wood quality. Here, we consider the physiological effects of fire scarring in white oak. Potential hydraulic conductivity, estimated from the mean vessel area and vessel number, was determined for growth rings formed before, during, and after the year of injury. We measured vessel anatomy using the ROXAS image analysis tool on the cross-sections of 14 white oaks of various ages with fire scars originating in different years through the late 19th and early 20th century. We found that the mean vessel area and potential hydraulic conductivity were significantly reduced for the year of and the year immediately following fire injury. After this two-year period, mean vessel area returned to levels present in wood formed prior to the injury. Age when scarred, radius from the pith when scarred, scar height above ground, and percentage of circumference scarred did not explain the degree to which potential hydraulic conductivity was lost in the fire scar year compared to the year prior. Overall, the magnitude of reduction in potential hydraulic conductivity was small but significant. An earlier study on the same cross-sections verified no reductions in radial growth after fire injury. Thus, it is likely that the conductance of older rings is adequate to sustain conductance. Nonetheless, we recommend further investigation, in particular, the ability to predict how tree size, age, position along a slope, and other variables may influence the degree of wounding and possible losses of potential hydraulic conductivity after the fire. Information like this for white oak and other common tree species may help elucidate the physiological impacts fire injuries have on trees existing in forest stands with periodic fire. Full article

(This article belongs to the Section Forest Ecology and Management)

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20 pages, 6766 KiB

Open AccessArticle

Use of MODIS NDVI Products to Map Tree Mortality Levels in Forests Affected by Mountain Pine Beetle Outbreaks

by Joseph P. Spruce, Jeffrey A. Hicke, William W. Hargrove, Nancy E. Grulke and Arjan J. H. Meddens

Forests 2019, 10(9), 811; https://doi.org/10.3390/f10090811 - 17 Sep 2019

Cited by 27 | Viewed by 4810

Abstract

Extensive bark beetle outbreaks have recently occurred in western North American forests, resulting in overstory tree mortality across millions of hectares. Annual aerial surveys are currently used to operationally monitor bark beetle induced tree mortality, though this method is subjective and can exclude [...] Read more.

Extensive bark beetle outbreaks have recently occurred in western North American forests, resulting in overstory tree mortality across millions of hectares. Annual aerial surveys are currently used to operationally monitor bark beetle induced tree mortality, though this method is subjective and can exclude some forest areas. Daily Moderate Resolution Imaging Spectroradiometer (MODIS) satellite data offer a potential alternative means to develop regional tree mortality maps. Accurate methods using such data could aid natural resource managers in surveys of forests with frequent overstory mortality, helping to prioritize forest treatment and restoration activities. This paper discusses a study to test the potential of using MODIS data to detect tree mortality. We developed and tested an approach to use 250-m resolution MODIS Normalized Difference Vegetation Index (NDVI) data products collected during a mountain pine beetle (MPB) outbreak and related tree mortality event in the northern Rocky Mountains of Colorado, USA. The 94 km² study area is predominantly lodgepole pine forest with most of the MPB-caused mortality occurring between 2003 and 2008. We used a 2.4-m forest conditions map from 2008 aerial multispectral imagery to calculate percentage of mortality within 240-m pixels for use as reference data. Using either daily or 16-day products, MODIS NDVI change products were calculated for 2008 versus either 2000 or 2003 baselines. MODIS change products were used as predictors in linear regression analysis to assess correlation between MODIS data and the aerial percent forest mortality map. Depending on the MODIS product, linear regression analyses yielded r² values ranging from 0.362 to 0.544 without outliers removed and from 0.406 to 0.570 with extreme outliers removed. Daily MODIS NDVI products from 2003 and 2008 were used with exponential regression to improve the r² to 0.593. The project showed some MODIS NDVI data potential for mapping percent tree mortality in forests subjected to regional bark beetle outbreaks and severe drought. Full article

(This article belongs to the Special Issue Dieback on Drought-Prone Forest Ecosystems)

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33 pages, 5421 KiB

Open AccessArticle

The Effect of Tree Crown Allometry on Community Dynamics in Mixed-Species Stands versus Monocultures. A Review and Perspectives for Modeling and Silvicultural Regulation

by Hans Pretzsch

Forests 2019, 10(9), 810; https://doi.org/10.3390/f10090810 - 17 Sep 2019

Cited by 57 | Viewed by 5529

Abstract

Many recent studies have shown that the structure, density, and productivity of mixed-species stands can differ from the weighted mean of monospecific stands of the respective species. The tree and stand properties emerging by inter-specific neighborhood should be considered in models for understanding [...] Read more.

Many recent studies have shown that the structure, density, and productivity of mixed-species stands can differ from the weighted mean of monospecific stands of the respective species. The tree and stand properties emerging by inter-specific neighborhood should be considered in models for understanding and practical management. A promising approach for this is a more realistic representation of the individual tree allometry in models and management concepts, as tree allometry determines many structural and functional aspects at the tree and stand level. Therefore, this paper is focused on the crown allometry in mixed and mono-specific stands. Firstly, we review species-specific differences in the crown allometry in monospecific stands. Secondly, we show how species-specific differences and complementarities in crown allometry can emerge in mixed-species stands. Thirdly, the consequences of allometric complementarity for the canopy packing density will be analyzed. Fourthly, we trace the crown allometry from the tree level to the stand density and show the relevance for the self-thinning in mixed versus monospecific stands. Fifth, the consequence of the findings for modeling and regulating tree and stand growth will be discussed. The review deals mainly with widespread even-aged, mono-layered stands, but the main results apply for more heterogeneous stands analogously. Full article

(This article belongs to the Special Issue Modelling Mixing Effects in Forest Stands)

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28 pages, 7009 KiB

Open AccessArticle

Spatial Pattern of Climate Change Effects on Lithuanian Forestry

by Gintautas Mozgeris, Vilis Brukas, Nerijus Pivoriūnas, Gintautas Činga, Ekaterina Makrickienė, Steigvilė Byčenkienė, Vitas Marozas, Marius Mikalajūnas, Vadimas Dudoitis, Vidmantas Ulevičius and Algirdas Augustaitis

Forests 2019, 10(9), 809; https://doi.org/10.3390/f10090809 - 17 Sep 2019

Cited by 12 | Viewed by 4814

Abstract

Research Highlights: Validating modelling approach which combines global framework conditions in the form of climate and policy scenarios with the use of forest decision support system to assess climate change impacts on the sustainability of forest management. Background and Objectives: Forests and forestry [...] Read more.

Research Highlights: Validating modelling approach which combines global framework conditions in the form of climate and policy scenarios with the use of forest decision support system to assess climate change impacts on the sustainability of forest management. Background and Objectives: Forests and forestry have been confirmed to be sensitive to climate. On the other hand, human efforts to mitigate climate change influence forests and forest management. To facilitate the evaluation of future sustainability of forest management, decision support systems are applied. Our aims are to: (1) Adopt and validate decision support tool to incorporate climate change and its mitigation impacts on forest growth, global timber demands and prices for simulating future trends of forest ecosystem services in Lithuania, (2) determine the magnitude and spatial patterns of climate change effects on Lithuanian forests and forest management in the future, supposing that current forestry practices are continued. Materials and Methods: Upgraded version of Lithuanian forestry simulator Kupolis was used to model the development of all forests in the country until 2120 under management conditions of three climate change scenarios. Selected stand-level forest and forest management characteristics were aggregated to the level of regional branches of the State Forest Enterprise and analyzed for the spatial and temporal patterns of climate change effects. Results: Increased forest growth under a warmer future climate resulted in larger tree dimensions, volumes of growing stock, naturally dying trees, harvested assortments, and also higher profits from forestry activities. Negative impacts were detected for the share of broadleaved tree species in the standing volume and the tree species diversity. Climate change effects resulted in spatially clustered patterns—increasing stand productivity, and amounts of harvested timber were concentrated in the regions with dominating coniferous species, while the same areas were exposed to negative dynamics of biodiversity-related forest attributes. Current forest characteristics explained 70% or more of the variance of climate change effects on key forest and forest management attributes. Conclusions: Using forest decision support systems, climate change scenarios and considering the balance of delivered ecosystem services is suggested as a methodological framework for validating forest management alternatives aiming for more adaptiveness in Lithuanian forestry. Full article

(This article belongs to the Special Issue Decision Support to Address Multiple Ecosystem Services in Forest Management Planning)

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16 pages, 2367 KiB

Open AccessArticle

Differential Responses and Controls of Soil CO₂ and N₂O Fluxes to Experimental Warming and Nitrogen Fertilization in a Subalpine Coniferous Spruce (Picea asperata Mast.) Plantation Forest

by Dandan Li, Qing Liu, Huajun Yin, Yiqi Luo and Dafeng Hui

Forests 2019, 10(9), 808; https://doi.org/10.3390/f10090808 - 17 Sep 2019

Cited by 13 | Viewed by 4465

Abstract

Emissions of greenhouse gases (GHG) such as CO₂ and N₂O from soils are affected by many factors such as climate change, soil carbon content, and soil nutrient conditions. However, the response patterns and controls of soil CO₂ and N [...] Read more.

Emissions of greenhouse gases (GHG) such as CO₂ and N₂O from soils are affected by many factors such as climate change, soil carbon content, and soil nutrient conditions. However, the response patterns and controls of soil CO₂ and N₂O fluxes to global warming and nitrogen (N) fertilization are still not clear in subalpine forests. To address this issue, we conducted an eight-year field experiment with warming and N fertilization treatments in a subalpine coniferous spruce (Picea asperata Mast.) plantation forest in China. Soil CO₂ and N₂O fluxes were measured using a static chamber method, and soils were sampled to analyze soil carbon and N contents, soil microbial substrate utilization (MSU) patterns, and microbial functional diversity. Results showed that the mean annual CO₂ and N₂O fluxes were 36.04 ± 3.77 mg C m⁻² h⁻¹ and 0.51 ± 0.11 µg N m⁻² h⁻¹, respectively. Soil CO₂ flux was only affected by warming while soil N₂O flux was significantly enhanced by N fertilization and its interaction with warming. Warming enhanced dissolve organic carbon (DOC) and MSU, reduced soil organic carbon (SOC) and microbial biomass carbon (MBC), and constrained the microbial metabolic activity and microbial functional diversity, resulting in a decrease in soil CO₂ emission. The analysis of structural equation model indicated that MSU had dominant direct negative effect on soil CO₂ flux but had direct positive effect on soil N₂O flux. DOC and MBC had indirect positive effects on soil CO₂ flux while soil NH₄⁺-N had direct negative effect on soil CO₂ and N₂O fluxes. This study revealed different response patterns and controlling factors of soil CO₂ and N₂O fluxes in the subalpine plantation forest, and highlighted the importance of soil microbial contributions to GHG fluxes under climate warming and N deposition. Full article

(This article belongs to the Special Issue Disturbance Effects on Soil Carbon and Greenhouse Gas Emissions in Forest Ecosystems)

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24 pages, 1946 KiB

Open AccessArticle

The Persistence of Container Nursery Treatments on the Field Performance and Root System Morphology of Longleaf Pine Seedlings

by Shi-Jean S. Sung, R. Kasten Dumroese, Jeremiah R. Pinto and Mary Anne S. Sayer

Forests 2019, 10(9), 807; https://doi.org/10.3390/f10090807 - 17 Sep 2019

Cited by 11 | Viewed by 3138

Abstract

In recent decades, container stock has become the preferred plant material to regenerate longleaf pine (Pinus palustris Mill.) forests in the southeastern United States. We evaluated the effects of container nursery treatments on early and long-term field performance in central Louisiana. Seedlings [...] Read more.

In recent decades, container stock has become the preferred plant material to regenerate longleaf pine (Pinus palustris Mill.) forests in the southeastern United States. We evaluated the effects of container nursery treatments on early and long-term field performance in central Louisiana. Seedlings were grown in four cavity volumes (60–336 mL) with or without copper oxychloride root pruning (Cu or no-Cu) and fertilized at three nitrogen (N) rates. Across treatments, 91% of the seedlings emerged from the grass stage by the second field season, and 88% of the seedlings survived eight years after outplanting (Year 8). Seedlings grown in the largest cavities had greater total heights and stem diameters than those cultured in the 60- and 95-mL cavities through Year 8. Seedlings receiving the least amount of N in the nursery were consistently smaller in stature through Year 8 than seedlings receiving more N. Field growth was unaffected by copper root pruning through Year 8. Foliar mineral nutrient concentrations and seedling nutrient contents of Year 2 seedlings did not respond to nursery treatments. Independent of nursery treatments, seedlings excavated in Year 2 had at least 60% of their first-order lateral roots (FOLRs) originating from the top 4.0 cm of the taproots. The Cu-root-pruned seedlings had twofold the percentage of FOLRs egressed from the top 8.0 cm of the root plug when compared with the no-Cu seedlings. Moreover, the Cu root pruning treatment decreased the percentage of root plug biomass allocated to FOLRs, total within root plug FOLR lengths, and FOLR deformity index. The effects of increasing cavity volume or N rate on the root plug FOLR variables were opposite those of the Cu root pruning treatment. Our results suggest that a tradeoff may exist between seedling stature and a more natural FOLR morphology in outplanted container longleaf pine seedlings. Full article

(This article belongs to the Special Issue Longleaf Pine)

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13 pages, 2009 KiB

Open AccessArticle

Forest Gap Size Alters the Functional Diversity of Soil Nematode Communities in Alpine Forest Ecosystems

by Ya Shen, Wanqin Yang, Jian Zhang, Zhenfeng Xu, Li Zhang, Yang Liu, Han Li, Chengming You and Bo Tan

Forests 2019, 10(9), 806; https://doi.org/10.3390/f10090806 - 16 Sep 2019

Cited by 6 | Viewed by 3104

Abstract

Changes in the microenvironment driven by forest gaps have profound effects on soil nutrient cycling and litter decomposition processes in alpine forest ecosystems. However, it is unclear whether a similar forest gap effect occurs in the soil decomposer community. A field experiment was [...] Read more.

Changes in the microenvironment driven by forest gaps have profound effects on soil nutrient cycling and litter decomposition processes in alpine forest ecosystems. However, it is unclear whether a similar forest gap effect occurs in the soil decomposer community. A field experiment was conducted in an alpine forest to investigate the composition and structure of the soil nematode community among four treatments, including under a closed canopy and in small (<10 m in diameter), medium (10–15 m in diameter), and large (15–20 m in diameter) gaps. A total of 92,787 individuals and 27 species (genera level) of soil nematode were extracted by elutriation and sugar centrifugation, respectively. Filenchus was the most abundant dominant taxa and represented 24.27–37.51% of the soil nematodes in the four treatments. Compared to the closed canopy, the forest gaps did not affect the composition, abundance, or species diversity of the soil nematode community but significantly affected the functional diversity of the soil nematode community. The maturity indices (MI, ∑MI, and MI2‒5) of the soil nematode community in the closed canopy were significantly lower than those in the forest gaps. Moreover, the proportion of plant parasitic index and maturity index (PPI/MI) values of the closed canopy and small gaps were significantly higher than those of the medium and large gaps. Our results suggest that the forest gap size substantially alters the functional diversity of soil nematodes in the debris food web, and changes in soil nematode community structure due to gap formation may have profound effects on soil biogeochemical processes in alpine forests. Full article

(This article belongs to the Special Issue Role of Gap Factors in Forest Tree Regeneration and Plant Communities)

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15 pages, 3436 KiB

Open AccessArticle

Machinability Study of Australia’s Dominate Plantation Timber Resources

by Nathan J. Kotlarewski, Mohammad Derikvand, Michael Lee and Ian Whiteroad

Forests 2019, 10(9), 805; https://doi.org/10.3390/f10090805 - 16 Sep 2019

Cited by 5 | Viewed by 3625

Abstract

This study tested the machinability of three major timber species grown in Tasmania, Australia, under different resource management schemes: plantation fiber-managed hardwood (Eucalyptus globulus Labill. and Eucalyptus nitens Maiden) and plantation sawlog-managed softwood (Pinus radiata D. Don). P. radiata was used [...] Read more.

This study tested the machinability of three major timber species grown in Tasmania, Australia, under different resource management schemes: plantation fiber-managed hardwood (Eucalyptus globulus Labill. and Eucalyptus nitens Maiden) and plantation sawlog-managed softwood (Pinus radiata D. Don). P. radiata was used as a control to identify significant differences in machining fibre-managed plantation timber against sawlog-managed plantation timber with numerically controlled computer technology and manually fed timber production techniques. The potential to fabricate architectural interior products such as moldings with plantation fiber-managed hardwood timber that is high in natural features was the focus of this study. Correlations between wood species, variation in moisture content, and density of individual machinability characteristics were analyzed to determine factors impacting the overall quality of plantation wood machinability. Correlations between species and within species groups from the resulting machinability tests are highlighted and discussed. The results indicate that the machinability of sawlog-managed softwood P. radiata is superior in some circumstances to fiber-managed hardwood E. globulus and E. nitens specimens, according to the American Society for Testing and Materials D1666-11. Full article

(This article belongs to the Special Issue Wood Properties and Processing)

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18 pages, 3441 KiB

Open AccessArticle

Drought Enhances the Role of Competition in Mediating the Relationship between Tree Growth and Climate in Semi-Arid Areas of Northwest China

by Kanglong Lu, Ning Chen, Cankun Zhang, Xiaoxue Dong and Changming Zhao

Forests 2019, 10(9), 804; https://doi.org/10.3390/f10090804 - 14 Sep 2019

Cited by 16 | Viewed by 3125

Abstract

Climate variability can exert a powerful impact on biotic competition, but past studies have focused largely on short-lived species, with a lack of attention to long-lived species such as trees. Therefore, there is a need to evaluate how competition regulates the climate-growth relationship [...] Read more.

Climate variability can exert a powerful impact on biotic competition, but past studies have focused largely on short-lived species, with a lack of attention to long-lived species such as trees. Therefore, there is a need to evaluate how competition regulates the climate-growth relationship in mature trees. We sampled the dominant tree species, Picea wilsonii Mast., on Xinglong Mountain, China, and studied the above issues by analyzing the relationship between tree radial growth, precipitation, and competition. In relatively wet years (precipitation > average), there was no significant difference in climate sensitivity between different competition classes. However, trees suffering from highly competitive stress were more sensitive to climate variability in all years, and particularly in the subset of years that was relatively drought (precipitation < average). These results suggest that competition enhances its ability to regulate tree growth response to climate variability in adverse weather conditions. Competition for resources between trees was asymmetrical, and an increase in height could give trees a disproportionate benefit. Thus, at trunk-level, both basal area incremental growth and intrinsic water-use efficiency of trees subjected to low competitive stress were significantly higher than trees that are subjected to highly competitive stress. Although the intrinsic water-use efficiency of trees under highly competitive stress increased more rapidly as the drought level increases, this did not change the fact that the radial growth of them declined more. Our research is valuable for the development of individual-tree growth models and advances our understanding for forest management under global climate change. Full article

(This article belongs to the Section Forest Ecology and Management)

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16 pages, 1590 KiB

Open AccessArticle

Modeling Experiments for Evaluating the Effects of Trees, Increasing Temperature, and Soil Texture on Carbon Stocks in Agroforestry Systems in Kerala, India

by Ann E. Russell and B. Mohan Kumar

Forests 2019, 10(9), 803; https://doi.org/10.3390/f10090803 - 14 Sep 2019

Cited by 10 | Viewed by 3578

Abstract

Research Highlights: Agroforestry systems in the humid tropics have the potential for high rates of production and large accumulations of carbon in plant biomass and soils and, thus, may play an important role in the global C cycle. Multiple factors can influence C [...] Read more.

Research Highlights: Agroforestry systems in the humid tropics have the potential for high rates of production and large accumulations of carbon in plant biomass and soils and, thus, may play an important role in the global C cycle. Multiple factors can influence C sequestration, making it difficult to discern the effect of a single factor. We used a modeling approach to evaluate the relative effects of individual factors on C stocks in three agricultural systems in Kerala, India. Background and Objectives: Factors such as plant growth form, management, climate warming, and soil texture can drive differences in C storage among cropping systems, but the relationships among these factors and their effects are complex. Our objective was to use CENTURY, a process-based model of plant–soil nutrient cycling, in an experimental mode to evaluate the effects of individual factors on C stocks in soil and biomass in monocultures (annuals or trees) and agroforestry systems. Materials and Methods: We parameterized the model for this region, then conducted simulations to investigate the effects on C stocks of four experimental scenarios: (1) change in growth form; (2) change in tree species; (3) increase in temperature above 20-year means; and (4) differences in soil texture. We compared the models with measured changes in soil C after eight years. Results: Simulated soil C stocks were influenced by all factors: growth form; lignin in tree tissues; increasing temperature; and soil texture. However, increasing temperature and soil sand content had relatively small effects on biomass C. Conclusions: Inclusion of trees with traits that promoted C sequestration such as lignin content, along with the use of best management practices, resulted in the greatest C storage among the simulated agricultural systems. Greater use and better management of trees with high C-storage potential can thus provide a low-cost means for mitigation of climate warming. Full article

(This article belongs to the Special Issue Agroforestry Systems: The Role of Trees in Ecosystem Services—A Special Issue in Collaboration with the 4th World Congress on Agroforestry)

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18 pages, 2807 KiB

Open AccessArticle

Modeling Migratory Flight in the Spruce Budworm: Temperature Constraints

by Jacques Régnière, Johanne Delisle, Brian R. Sturtevant, Matthew Garcia and Rémi Saint-Amant

Forests 2019, 10(9), 802; https://doi.org/10.3390/f10090802 - 13 Sep 2019

Cited by 12 | Viewed by 3037

Abstract

We describe an individual-based model of spruce budworm moth migration founded on the premise that flight liftoff, altitude, and duration are constrained by the relationships between wing size, body weight, wingbeat frequency, and air temperature. We parameterized this model with observations from moths [...] Read more.

We describe an individual-based model of spruce budworm moth migration founded on the premise that flight liftoff, altitude, and duration are constrained by the relationships between wing size, body weight, wingbeat frequency, and air temperature. We parameterized this model with observations from moths captured in traps or observed migrating under field conditions. We further documented the effects of prior defoliation on the size and weight (including fecundity) of migrating moths. Our simulations under idealized nocturnal conditions with a stable atmospheric boundary layer suggest that the ability of gravid female moths to migrate is conditional on the progression of egg-laying. The model also predicts that the altitude at which moths migrate varies with the temperature profile in the boundary layer and with time during the evening and night. Model results have implications for the degree to which long-distance dispersal by spruce budworm might influence population dynamics in locations distant from outbreak sources, including how atmospheric phenomena such as wind convergence might influence these processes. To simulate actual migration flights en masse, the proposed model will need to be linked to regional maps of insect populations, a phenology model, and weather model outputs of both large- and small-scale atmospheric conditions. Full article

(This article belongs to the Special Issue Protection Strategy against Spruce Budworm)

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16 pages, 3833 KiB

Open AccessArticle

Stakeholders’ Perceptions of Geographical Criteria for Loblolly Pine Management for Bioenergy Production in Virginia

by Meghann Smith, Gia Nguyen, Taylor Wieczerak, Bernabas Wolde, Pankaj Lal and John Munsell

Forests 2019, 10(9), 801; https://doi.org/10.3390/f10090801 - 12 Sep 2019

Cited by 5 | Viewed by 3453

Abstract

This study analyzed the perceptions of four stakeholder groups (forest landowners, private forest consultants, forest management researchers or educators, and federal or state agency foresters), regarding their management practices and preferred geographic growing conditions of loblolly pine in Virginia by combining AHP (analytical [...] Read more.

This study analyzed the perceptions of four stakeholder groups (forest landowners, private forest consultants, forest management researchers or educators, and federal or state agency foresters), regarding their management practices and preferred geographic growing conditions of loblolly pine in Virginia by combining AHP (analytical hierarchy process) and regression modeling. By ranking the importance of different geographical conditions for managing loblolly pine, we aimed to identify ways to support loblolly growth as a potential feedstock for biofuel generation. We achieved this through collecting survey responses from 43 stakeholders during the 2019 Virginia Forestry Summit. The results showed that the landowner, researcher/educator, and federal/state agency stakeholder groups all indicated that proximity to a mill was the most important criteria, whereas the consultant stakeholder group indicated that proximity to a road was the most important criteria. All the stakeholder groups indicated that distance from protected land was the least important criteria, followed by proximity to a water body and flat land. The regression model revealed that acres of land managed and loblolly rotation age were correlated to the weight given to the distance to a mill criterion, where increased acreage and increased rotation age were associated with an increased prioritization of proximity to a mill. Distance from protected land, the lowest-ranking criteria, was shown to have an association with the level of experience with loblolly, where more experience was associated with a lower prioritization of proximity from protected land. A contingency analysis of the self-identified level of experience with loblolly in each stakeholder group revealed that federal/state agency foresters had the most experience, followed by consultants, landowners, and researchers/educators. The research supports the importance of understanding the variation of perceptions between and within stakeholder groups in order to develop the necessary infrastructural and policy support for the sustainable development of bioenergy. Full article

(This article belongs to the Special Issue Ecological Insights into the Sustainable Development of Bioenergy from Forests)

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17 pages, 1233 KiB

Open AccessReview

Catering Information Needs from Global to Local Scales—Potential and Challenges with National Forest Inventories

by Annika Kangas, Minna Räty, Kari T. Korhonen, Jari Vauhkonen and Tuula Packalen

Forests 2019, 10(9), 800; https://doi.org/10.3390/f10090800 - 12 Sep 2019

Cited by 12 | Viewed by 3774

Abstract

Forest information is needed at global, national and local scales. This review aimed at providing insights of potential of national forest inventories (NFIs) as well as challenges they have to cater to those needs. Within NFIs, the authors address the methodological challenges introduced [...] Read more.

Forest information is needed at global, national and local scales. This review aimed at providing insights of potential of national forest inventories (NFIs) as well as challenges they have to cater to those needs. Within NFIs, the authors address the methodological challenges introduced by the multitude of scales the forest data are needed, and the challenges in acknowledging the errors due to the measurements and models in addition to sampling errors. Between NFIs, the challenges related to the different harmonization tasks were reviewed. While a design-based approach is often considered more attractive than a model-based approach as it is guaranteed to provide unbiased results, the model-based approach is needed for downscaling the information to smaller scales and acknowledging the measurement and model errors. However, while a model-based inference is possible in small areas, the unknown random effects introduce biased estimators. The NFIs need to cater for the national information requirements and maintain the existing time series, while at the same time providing comparable information across the countries. In upscaling the NFI information to continental and global information needs, representative samples across the area are of utmost importance. Without representative data, the model-based approaches enable provision of forest information with unknown and indeterminable biases. Both design-based and model-based approaches need to be applied to cater to all information needs. This must be accomplished in a comprehensive way In particular, a need to have standardized quality requirements has been identified, acknowledging the possibility for bias and its implications, for all data used in policy making. Full article

(This article belongs to the Special Issue Forest Resources Assessments: Mensuration, Inventory and Planning)

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19 pages, 10001 KiB

Open AccessArticle

Bark Features for Identifying Resonance Spruce Standing Timber

by Florin Dinulică, Cristian-Teofil Albu, Maria Magdalena Vasilescu and Mariana Domnica Stanciu

Forests 2019, 10(9), 799; https://doi.org/10.3390/f10090799 - 12 Sep 2019

Cited by 14 | Viewed by 3415

Abstract

Measuring the acoustic properties of wood is not feasible for most luthiers, so identifying simple, valid criteria for diagnosis remains an exciting challenge when selecting materials for manufacturing musical instruments. This article aims to verify whether the bark qualities as a marker of [...] Read more.

Measuring the acoustic properties of wood is not feasible for most luthiers, so identifying simple, valid criteria for diagnosis remains an exciting challenge when selecting materials for manufacturing musical instruments. This article aims to verify whether the bark qualities as a marker of resonance wood are indeed useful. The morphometric and colour traits (in CIELab space) of the bark scales were compared with the structural (width and regularity of the growth rings and of the latewood) and acoustic features (transverse sound velocity, radiation ratio, impedance, and wood basic density) of the wood from 145 standing and 10 felled spruce trees, which are considered a resource of the resonance wood in the Romanian Carpathians. It has been emphasized that the spruce trees with acoustic and structural features that match the requirements for the manufacture of violins have a bark phenotype distinguishable by colour (higher redness, lower yellowness and brightness)—as well as by scale shape (higher slenderness and width). The south-facing side of the trunk and the external side of the scale are best for identifying resonance trees by their bark. Additionally, the mature bark phenotypes denote topoclinal variations and do not depend on tree age. Moreover, the differences among bark phenotypes are noticeable to the naked eye. Full article

(This article belongs to the Special Issue Genetic and Phenotypic Variation in Tree Crops Biodiversity)

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14 pages, 1895 KiB

Open AccessArticle

Drivers of the Distribution of Ecological Species Groups in Temperate Deciduous Managed Forests in the Western Carpathian Mountains

by Marian Gabor, Pavel Beracko, Vladimir Faltan, Igor Matecny, Lukas Karlik, František Petrovič, Dusan Vallo and Ivo Machar

Forests 2019, 10(9), 798; https://doi.org/10.3390/f10090798 - 12 Sep 2019

Cited by 4 | Viewed by 2638

Abstract

Managed broadleaf deciduous forests are an important type of forest vegetation in Central Europe, also in the Western Carpathians. These forests are both economically and environmentally valuable. However, little is known about ecological species groups and the inter-specific associations of dominant species in [...] Read more.

Managed broadleaf deciduous forests are an important type of forest vegetation in Central Europe, also in the Western Carpathians. These forests are both economically and environmentally valuable. However, little is known about ecological species groups and the inter-specific associations of dominant species in temperate deciduous managed forests in Central Europe. Since the forest stands are in a managed landscape, they are not consistent with the traditionally recognized and used vegetation associations in the Western Carpathians. For these reasons our research contributes to understanding the consequences of broadleaf deciduous forest management. The aim of this research was the determination of ecological species groups and an investigation into the main environmental drivers, in order to explain the distribution of ecological species groups. The numerical TWINSPAN classification was selected to distribute 146 relevés to the five ecological species groups. Of these, 77 relevés were divided into two groups with Fagus sylvatica dominant, while 63 relevés were Quercus petraea dominant. Carpinus betulus, Tilia cordata and Fraxinus excelsior were dominant in 19 relevés. Constrained Analysis of Principal Components was used to explain the vegetation–environment relationship on three transects in the Male Karpaty Mountains. Altitude, pH, Ca, C, K and Mg were selected as the significant environmental drivers responsible for a large part of the species group variability (31.8%). The main requirement for sustainable forest management is knowledge of the vegetation–environment relationship and this research was focused on gaining such understanding. This knowledge can be used as a decision support tool for sustainable management in managed deciduous forests. Full article

(This article belongs to the Section Forest Ecology and Management)

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16 pages, 3260 KiB

Open AccessArticle

The Composition and Diversity of Soil Bacterial and Fungal Communities Along an Urban-To-Rural Gradient in South China

by Xuelian Tan, Lei Kan, Zhiyao Su, Xiaodong Liu and Lu Zhang

Forests 2019, 10(9), 797; https://doi.org/10.3390/f10090797 - 12 Sep 2019

Cited by 27 | Viewed by 3972

Abstract

Soil microbes are of great significance to driving the biogeochemical cycles and are affected by multiple factors, including urbanization. However, the response of soil microbes to urbanization remains unclear. Therefore, we designed an urban-to-rural gradient experiment to investigate the response of soil microbial [...] Read more.

Soil microbes are of great significance to driving the biogeochemical cycles and are affected by multiple factors, including urbanization. However, the response of soil microbes to urbanization remains unclear. Therefore, we designed an urban-to-rural gradient experiment to investigate the response of soil microbial composition and diversity to urbanization. Here, we used a high-throughput sequencing method to analyze the biotic and abiotic effects on soil microbial composition and diversity along the urban-to-rural gradient. Our results showed that soil bacterial diversity was the highest in urban areas, followed by suburban areas, and was the lowest in exurbs; however, fungal diversity did not vary significantly among the three areas. Plant traits, i.e., tree richness, shrub richness, the number of tree stems, diameter at breast height of trees, and soil properties, i.e., pH, soil organic carbon, soil exchangeable calcium and magnesium, and soil water content, were only significantly influenced bacterial diversity, but not fungal diversity. The effect of trees and shrubs was higher than that of herbs on microbial composition. Soil organic carbon, pH, soil available nitrogen, soil exchangeable calcium, and magnesium were the major soil factors influencing the soil bacterial and fungal composition. Soil properties had a greater influence on bacterial than on fungal composition at genus level, while plant traits contributed more to fungal than to bacterial composition at genus level. Our study suggests that the urban-to-rural gradient affect the composition and diversity of bacterial community as well as the fungal composition, but not the fungal diversity. Full article

(This article belongs to the Section Forest Ecophysiology and Biology)

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18 pages, 3710 KiB

Open AccessArticle

Effects of Vegetation Restoration on the Distribution of Nutrients, Glomalin-Related Soil Protein, and Enzyme Activity in Soil Aggregates on the Loess Plateau, China

by Leilei Qiao, Yuanze Li, Yahui Song, Jiaying Zhai, Yang Wu, Wenjing Chen, Guobin Liu and Sha Xue

Forests 2019, 10(9), 796; https://doi.org/10.3390/f10090796 - 12 Sep 2019

Cited by 28 | Viewed by 3983

Abstract

Research Highlights: Soil enzymes have a significant impact on the production of glomalin-related soil protein (GRSP), directly and indirectly affecting the nutrient metabolism balance, but there is little available information on ecological stoichiometry in soil aggregates. Background and Objectives: Vegetation restoration changes community [...] Read more.

Research Highlights: Soil enzymes have a significant impact on the production of glomalin-related soil protein (GRSP), directly and indirectly affecting the nutrient metabolism balance, but there is little available information on ecological stoichiometry in soil aggregates. Background and Objectives: Vegetation restoration changes community structure and species composition in ecosystems, thus changing the physicochemical properties of soil. Soil aggregate is the most basic physical structure of the soil. Therefore, in order to understand dynamic changes in soil aggregate nutrients as vegetation restoration progresses, we set out to investigate the nutrient distribution and utilization in aggregates, and how enzymes respond to the nutrient changes in achieving a nutritional balance along successive stages of vegetation restoration. Materials and Methods: We collected and analyzed soil from plots representing six different stages of a vegetation restoration chronosequence (0, 30, 60, 100, 130, and 160 years) after farmland abandonment on the Loess Plateau, China. We investigated soil nutrient stoichiometry, GRSP, and enzyme stoichiometry in the different successional stages. Results: The results revealed that soil organic carbon, total nitrogen, enzyme activity, and GRSP increased with vegetation recovery age, but not total phosphorus, and not all enzymes reached their maximum in the climax forest community. The easily extractable GRSP/total GRSP ratio was the largest at the shrub community stage, indicating that glomalin degradation was the lowest at this stage. Ecological stoichiometry revealed N-limitation decreased and P-limitation increased with increasing vegetation restoration age. Soil enzymes had a significant impact on the GRSP production, directly and indirectly affecting nutrient metabolism balance. Conclusions: Further study of arbuscular mycorrhizal fungi to identify changes in their category and composition is needed for a better understanding of how soil enzymes affect their release of GRSP, in order to maintain a nutrient balance along successive stages of vegetation restoration. Full article

(This article belongs to the Section Forest Ecology and Management)

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11 pages, 3453 KiB

Open AccessArticle

Aboveground Biomass Response to Release Treatments in a Young Ponderosa Pine Plantation

by Martin Ritchie, Jianwei Zhang and Ethan Hammett

Forests 2019, 10(9), 795; https://doi.org/10.3390/f10090795 - 12 Sep 2019

Cited by 1 | Viewed by 2810

Abstract

Controlling competing vegetation is vital for early plantation establishment and growth. Aboveground biomass (AGB) response to manual grubbing release from shrub competition was compared with no release control in a twelve-year-old ponderosa pine (Pinus ponderosa Lawson & C. Lawson) plantation established after [...] Read more.

Controlling competing vegetation is vital for early plantation establishment and growth. Aboveground biomass (AGB) response to manual grubbing release from shrub competition was compared with no release control in a twelve-year-old ponderosa pine (Pinus ponderosa Lawson & C. Lawson) plantation established after a wildfire in northeastern California. In addition, response to chemical release followed by precommercial thinning in an adjacent plantation was also examined as a growth potential from a more intensively managed regime, where shrub competition was virtually eliminated. We measured AGB in both planted trees and competing woody shrubs to partition the biomass pools in the plantation. The results showed a significant grubbing treatment effect on basal diameter (BD) at 10 cm aboveground (p = 0.02), but not on tree height (p = 0.055). Height and BD were 2.0 m and 7.4 cm in the manual release, respectively, compared to 1.7 m and 5.6 cm in the control. However, chemical release produced much greater rates of tree growth with a height of 3.6 m and BD of 14.7 cm, respectively. Tree AGB was 60% higher with the manual release of shrubs (1.2 Mg ha⁻¹) than with control (0.7 Mg ha⁻¹) (p < 0.05). The planted area without shrub competition yielded a much higher green tree biomass (16.0 Mg ha⁻¹). When woody shrub biomass was included, the total AGB (trees and woody shrubs) appeared slightly higher, but non-significant in the no release control (13.3 Mg ha⁻¹) than in the manual release (11.9 Mg ha⁻¹) (p = 0.66); the chemical release had 17.1 Mg ha⁻¹. Clearly, shrub biomass dominated this young plantation when understory shrubs were not completely controlled. Although the manual release did increase targeted tree growth to some degree, the cost may limit this practice to a smaller scale and the remaining shrub dominance may create long-term reductions in growth and a persistent fuels problem in these fire-prone ecosystems. Full article

(This article belongs to the Special Issue Growth and Allocation of Woody Biomass in Forest Trees Based on Environmental Conditions)

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19 pages, 790 KiB

Open AccessArticle

How to Achieve Effective Participation of Communities in the Monitoring of REDD+ Projects: A Case Study in the Democratic Republic of Congo (DRC)

by Christine B. Schmitt and Joëlle Mukungu

Forests 2019, 10(9), 794; https://doi.org/10.3390/f10090794 - 12 Sep 2019

Cited by 10 | Viewed by 3395

Abstract

Developing countries that implement the Reducing emissions from deforestation and forest degradation (REDD+) mechanism under the United Nations Framework Convention on Climate Change are required to ensure the effective participation of all stakeholders including indigenous peoples and local communities. Community-based monitoring (CBM) of [...] Read more.

Developing countries that implement the Reducing emissions from deforestation and forest degradation (REDD+) mechanism under the United Nations Framework Convention on Climate Change are required to ensure the effective participation of all stakeholders including indigenous peoples and local communities. Community-based monitoring (CBM) of REDD+ projects could contribute to meeting REDD+ monitoring, reporting, and verification requirements and to ensuring effective community participation. The Democratic Republic of Congo (DRC) is the most advanced country in REDD+ implementation in the Congo Basin region, but the role of forest communities in REDD+ monitoring has not been adequately defined. Based on a Delphi survey, this study aimed to explore the factors that are crucial in achieving effective community participation in the monitoring of REDD+ projects. Out of 65 experts with in-depth knowledge of REDD+ and CBM in the DRC and elsewhere, 35 agreed to participate in the study. In three rounds, 19 feedbacks were received from the first round, 17 from the second and 14 from the third. Data were analyzed in a qualitative (MAXQDA) and quantitative (Microsoft Excel) manner. There was consensus among experts that, per definition, effective participation of communities in the monitoring of REDD+ projects must be a process characterized by a free and prior informed consent (FPIC), recognition of traditional knowledge and community rights, and involvement of communities in all steps of the monitoring process. In practice, the latter point poses several challenges as it requires capacity building, careful selection of indicators, adequate local institutional arrangements and a benefit-sharing system. Ideally, local CBM systems should be nested within the national forest monitoring system, but this will require more strategic efforts at the national level in the DRC, including a framework concept for the role of communities and CBM in REDD+ that can be further adapted to particular circumstances on the ground. Full article

(This article belongs to the Section Forest Economics, Policy, and Social Science)

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Forests, Volume 10, Issue 9 (September 2019) – 115 articles

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