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Forests
Volume 9
Issue 5
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Forests, Volume 9, Issue 5 (May 2018) – 58 articles

Cover Story (view full-size image): We used chainsaws to carve artificial hollows directly into the trunks and branches of live Eucalyptus trees, thereby avoiding the long time delays taken for these keystone habitat features to develop via natural processes. The ‘chainsaw hollows’ produced thermally stable microhabitats similar to natural tree hollows, and could potentially provide supplementary hollows that buffer hollow-dependent fauna from weather extremes. View this paper
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23 pages, 2658 KiB  
Review
Seedling Quality: History, Application, and Plant Attributes
by Steven C. Grossnickle and Joanne E. MacDonald
Forests 2018, 9(5), 283; https://doi.org/10.3390/f9050283 - 22 May 2018
Cited by 80 | Viewed by 9319
Abstract
Since the early 20th century, silviculturists have recognized the importance of planting seedlings with desirable attributes, and that these attributes are associated with successful seedling survival and growth after outplanting. Over the ensuing century, concepts on what is meant by a quality seedling [...] Read more.
Since the early 20th century, silviculturists have recognized the importance of planting seedlings with desirable attributes, and that these attributes are associated with successful seedling survival and growth after outplanting. Over the ensuing century, concepts on what is meant by a quality seedling have evolved to the point that these assessments now provide value to both the nursery practitioner growing seedlings and the forester planting seedlings. Various seedling quality assessment procedures that measure numerous morphological and physiological plant attributes have been designed and applied. This paper examines the historical development of the discipline of seedling quality, as well as where it is today. It also examines how seedling quality is employed in forest restoration programs and the attributes that are measured to define quality. The intent is to provide readers with an overall perspective on the field of seedling quality and the people who developed this discipline from an idea into an operational reality. Full article
(This article belongs to the Special Issue Seedling Production and Field Performance of Seedlings)
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15 pages, 2660 KiB  
Article
Invasive Species May Disrupt Protected Area Networks: Insights from the Pine Wood Nematode Spread in Portugal
by Begoña De la Fuente and Pieter S. A. Beck
Forests 2018, 9(5), 282; https://doi.org/10.3390/f9050282 - 22 May 2018
Cited by 18 | Viewed by 6247
Abstract
The expansion of invasive alien species is considered a major threat to forest ecosystems and biodiversity. Their potential impacts range from local changes in species composition to wider-scale effects on forest habitat and landscape functioning, although the latter has been relatively little explored [...] Read more.
The expansion of invasive alien species is considered a major threat to forest ecosystems and biodiversity. Their potential impacts range from local changes in species composition to wider-scale effects on forest habitat and landscape functioning, although the latter has been relatively little explored in the literature. Here, we assessed the impact of an invasive forest pest, the pine wood nematode (PWN), in the Natura 2000 network of protected areas (PAs) in Portugal, the first European country in which PWN was reported. We considered the impacts of the pest’s spread (up to 2016) on individual PAs, in terms of the fraction of their coniferous forest infected, and on the corridors between PAs, which were mapped and prioritized through least-cost path modelling, geographic information system analysis, and the graph-based probability of connectivity metric. We found that PWN by 2016 had spread into 49% of the Portuguese Natura 2000 coniferous forest habitat, while it had invaded 68% of the coniferous forests that form the priority corridors between the PAs. These impacts are likely to be aggravated in the next years, given the pace of PWN expansion and the predicted rates of natural spread to new areas in Portugal and, increasingly likely, in Spain. Our results suggest that the connectivity of PA systems may be significantly disrupted by alien species, and that spatially prioritized control measures can help mitigate the impacts of invasive species on the coherence and functionality of protected area networks such as Natura 2000. Full article
(This article belongs to the Section Forest Ecology and Management)
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17 pages, 4205 KiB  
Article
Interactions between Vegetation, Hydrology, and Litter Inputs on Decomposition and Soil CO2 Efflux of Tropical Forests in the Brazilian Pantanal
by Osvaldo Borges Pinto, George L Vourlitis, Edna Maria De Souza Carneiro, Marizeth De França Dias, Cloe Hentz and Jose De Souza Nogueira
Forests 2018, 9(5), 281; https://doi.org/10.3390/f9050281 - 22 May 2018
Cited by 10 | Viewed by 4182
Abstract
Climate change has the capacity to alter water availability and the litter production of tropical forests, which will alter rates of carbon (C) cycling and storage. We conducted a short-term field experiment in two hydrologically diverse forests in the Brazilian Pantanal to assess [...] Read more.
Climate change has the capacity to alter water availability and the litter production of tropical forests, which will alter rates of carbon (C) cycling and storage. We conducted a short-term field experiment in two hydrologically diverse forests in the Brazilian Pantanal to assess the initial response of litter decomposition and soil respiration (Rsoil) to variations in litter pool size. Total annual Rsoil and decomposition significantly declined with litter removal and increased with litter addition, but the rate of litter decomposition was highest for plots where litter was removed. Rsoil was positively related to soil organic matter content and the rate of litter decomposition, but not soil moisture or temperature, suggesting that the litter treatment effects on decomposition and Rsoil were due to changes in C availability and not litter effects on the soil environment (i.e., temperature and moisture). Rsoil was not significantly different between the forests studied here even though they had large differences in hydrology; however, litter decomposition was significantly higher in seasonally flooded forest, especially when augmented with litter. These results suggest that alterations in litter production from land use and/or climate change will alter short-term rates of decomposition and Rsoil for these and other floodplain forests of the Pantanal and Amazon Basin. Full article
(This article belongs to the Special Issue Impact of Global Change on Soil Carbon Storage and Biogeochemical Cycles in Tropical Forest Ecosystems)
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22 pages, 4541 KiB  
Article
Evaluation of Salvage Logging Productivity and Costs in Windthrown Norway Spruce-Dominated Forests
by Kalle Kärhä, Tuomas Anttonen, Asko Poikela, Teijo Palander, Ari Laurén, Heli Peltola and Yrjö Nuutinen
Forests 2018, 9(5), 280; https://doi.org/10.3390/f9050280 - 22 May 2018
Cited by 36 | Viewed by 4852
Abstract
Different abiotic and biotic disturbances are expected to become more common in the future due to a warming climate. Globally, post-disturbance salvage logging is becoming more predominant to recover economic value from timber in disturbed forests. This study collected comparative time-study data and [...] Read more.
Different abiotic and biotic disturbances are expected to become more common in the future due to a warming climate. Globally, post-disturbance salvage logging is becoming more predominant to recover economic value from timber in disturbed forests. This study collected comparative time-study data and analyzed the productivity of cutting for windfalls in clear cuttings and determined the cutting costs of windfalls. Furthermore, the logging (i.e., cutting and forwarding) costs of wind-damaged trees and those of undamaged standing Norway spruce (Picea abies (L.) Karst.) trees in clear cuts were calculated in Finland. The results revealed that the cutting productivity of windfalls was 19–33% lower than that of undamaged stems. The cutting costs of windthrown stems with a volume of 0.3–1.5 m3 were 35–64% higher and the logging costs of windfalls were 10–30% higher than those of undamaged standing stems. The study provided new understanding regarding the productivity and costs of salvage logging operations under Finnish conditions. Even if the logging of windfalls is expensive and laborious, salvage logging operations are important for forest stands and their health to minimize post-disaster damage outbreaks in coniferous forests, such as the damage caused by bark beetles—mainly Ips typographus L. Full article
(This article belongs to the Section Forest Ecology and Management)
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7 pages, 1036 KiB  
Communication
Tree Vitality Assessment in Urban Landscapes
by David Callow, Peter May and Denise M. Johnstone
Forests 2018, 9(5), 279; https://doi.org/10.3390/f9050279 - 21 May 2018
Cited by 21 | Viewed by 6755
Abstract
The recent prolonged drought in Melbourne, Australia has had a deleterious effect on the urban forest, resulting in the premature decline of many mature trees and a consequent decline in the environmental services that trees are able to provide to urban residents. Measuring [...] Read more.
The recent prolonged drought in Melbourne, Australia has had a deleterious effect on the urban forest, resulting in the premature decline of many mature trees and a consequent decline in the environmental services that trees are able to provide to urban residents. Measuring the severity of tree stress and defoliation due to various climatic factors is essential to the ongoing delivery of environmental services such as shade and carbon sequestration. This study evaluates two methods to assess the vitality of drought stressed Elm trees within an inner-city environment—bark chlorophyll fluorescence measured on large branches and an urban visual vitality index. Study species were Ulmus procera Salisb. (English Elm) and Ulmus × hollandica (Dutch Elm), which are important character and shade tree species for Melbourne. Relationships were identified between leaf water potential and the urban visual vitality index and between leaf water potential and bark chlorophyll fluorescence measured on large branches, indicating that these methods could be used to assess the effect of long-term drought and other stressors on urban trees. Full article
(This article belongs to the Special Issue Growth and Ecosystem Services of Urban Trees)
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18 pages, 5028 KiB  
Article
Short-Term Vegetation Responses Following Windthrow Disturbance on Preserved Forest Lands
by Douglas R. Manning, Margot W. Kaye, Stephanie J. Perles and David A. Mortensen
Forests 2018, 9(5), 278; https://doi.org/10.3390/f9050278 - 21 May 2018
Cited by 1 | Viewed by 4792
Abstract
Invasive exotic plants pose a serious threat to the ecological integrity of forests in the eastern United States. Presence and expansion of these plants are closely associated with human-caused disturbances. Land preservation to exclude human-caused disturbances could protect against invasions, yet natural disturbances [...] Read more.
Invasive exotic plants pose a serious threat to the ecological integrity of forests in the eastern United States. Presence and expansion of these plants are closely associated with human-caused disturbances. Land preservation to exclude human-caused disturbances could protect against invasions, yet natural disturbances persist. We ask if windthrow forest disturbances in preserved National Park lands facilitate exotic species invasions. We hypothesized that exotic plant expansion is positively correlated with forest canopy disturbance from windthrow and proximity of disturbed area to forest edge. Pre and post-disturbance data from National Park Service long-term vegetation monitoring were used to analyze exotic plant richness and abundance in four National Park Service units affected by 2012 severe storms. No significant difference in exotic plant richness or cover occurred between disturbed (n = 18) and undisturbed plots (n = 262) over three years following disturbance. Exotic plant cover prior to disturbance was positively correlated with the amount of nearby linear edge habitat, but there were no significant correlations between edge and change in exotic plant cover following disturbance. Lack of increase in exotic plants after windthrow disturbance suggests that land preservation provides short-term resistance to invasion. Full article
(This article belongs to the Special Issue Ecology and Management of Invasive Species in Forest Ecosystems)
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19 pages, 6927 KiB  
Article
The Application of Two Approaches Using GIS Technology Implementation in Forest Road Network Planning in an Italian Mountain Setting
by Rodolfo Picchio, Giuseppe Pignatti, Enrico Marchi, Francesco Latterini, Mirko Benanchi, Cristiano Foderi, Rachele Venanzi and Stefano Verani
Forests 2018, 9(5), 277; https://doi.org/10.3390/f9050277 - 19 May 2018
Cited by 58 | Viewed by 8125
Abstract
A well-planned forest road network is essential for meeting the goal of sustainable forest management. Forest roads play a key role in commercial purposes, fire prevention, and recreational activities. The aim of this work was to apply precision forestry in the analysis of [...] Read more.
A well-planned forest road network is essential for meeting the goal of sustainable forest management. Forest roads play a key role in commercial purposes, fire prevention, and recreational activities. The aim of this work was to apply precision forestry in the analysis of the forest network of two forest ownerships in Tuscany. A proposal was formulated based on the information obtained regarding future forest road construction. This proposal takes into consideration technical effectiveness and environmental sustainability, with particular attention paid to low-impact logging. Two systems were tested so as to gain a better comprehension of different technical approaches. One system was reported by other researchers and the other was developed by the authors of this paper. The aim was to provide a valid instrument and possible alternative for forest managers involved in decision making. This study highlights the importance of precision forestry, even on a small-scale technical application level in forest road planning, thus helping managers and owners during the decision-making process in forestry operations. Full article
(This article belongs to the Special Issue Forest Operations: Planning, Innovation and Sustainability)
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13 pages, 1109 KiB  
Article
Solid Wood Properties Assessed by Non-Destructive Measurements of Standing European Larch (Larix decidua Mill.): Environmental Effects on Variation within and among Trees and Forest Stands
by Petr Škorpík, Heino Konrad, Thomas Geburek, Michael Schuh, David Vasold, Michael Eberhardt and Silvio Schueler
Forests 2018, 9(5), 276; https://doi.org/10.3390/f9050276 - 18 May 2018
Cited by 10 | Viewed by 3590
Abstract
To avoid unintentional loss of wood quality when selecting for higher productivity in tree breeding programs, non-destructive methods for fast and reliable assessment of wood quality on standing trees are required. In this study, we tested and applied Pilodyn penetration (PP) and measures [...] Read more.
To avoid unintentional loss of wood quality when selecting for higher productivity in tree breeding programs, non-destructive methods for fast and reliable assessment of wood quality on standing trees are required. In this study, we tested and applied Pilodyn penetration (PP) and measures of stress wave velocity (SWV) in trees within a European larch (Larix decidua Mill.) breeding program. Through testing PP in 4267 trees on 21 afforestation sites across a broad climatic spectrum, we analysed the effects of climate, tree age, and site conditions on PP. Moreover, detailed measures within two selected stands allowed us to estimate measurement variation within and among trees in relation to the measurement angle and individual tree characteristics. We found significant variation of PP and SWV among forests stands, single trees, and even within trees, if measured on opposite sides in mountainous terrain. Both measurements exhibited a high degree of genetic determination, i.e., repeatability was 0.32–0.61 for PP and 0.56 for SWV, respectively. The obtained estimates for wood stiffness were comparable to measures on harvested wood samples of European or hybrid larch. Our results demonstrate that the integration of wood quality parameters into larch breeding programs is highly recommended, and reliable tools are available. Results are discussed in relation to environmental and measurement variation and methods to optimize field measurements are suggested. Full article
(This article belongs to the Special Issue Wood Property Responses to Silvicultural Treatments)
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23 pages, 9577 KiB  
Article
Estimation of Forest Aboveground Biomass and Leaf Area Index Based on Digital Aerial Photograph Data in Northeast China
by Dan Li, Xingfa Gu, Yong Pang, Bowei Chen and Luxia Liu
Forests 2018, 9(5), 275; https://doi.org/10.3390/f9050275 - 18 May 2018
Cited by 33 | Viewed by 6257
Abstract
Forest aboveground biomass (AGB) and leaf area index (LAI) are two important parameters for evaluating forest growth and health. It is of great significance to estimate AGB and LAI accurately using remote sensing technology. Considering the temporal resolution and data acquisition costs, digital [...] Read more.
Forest aboveground biomass (AGB) and leaf area index (LAI) are two important parameters for evaluating forest growth and health. It is of great significance to estimate AGB and LAI accurately using remote sensing technology. Considering the temporal resolution and data acquisition costs, digital aerial photographs (DAPs) from a digital camera mounted on an unmanned aerial vehicle or light, small aircraft have been widely used in forest inventory. In this study, the aerial photograph data was acquired on 5 and 9 June, 2017 by a Hasselblad60 digital camera of the CAF-LiCHy system in a Y-5 aircraft in the Mengjiagang forest farm of Northeast China, and the digital orthophoto mosaic (DOM) and photogrammetric point cloud (PPC) were generated from an aerial overlap photograph. Forest red-green-blue (RGB) vegetation indices and textural factors were extracted from the DOM. Forest vertical structure features and canopy cover were extracted from normalized PPC. Regression analysis was carried out considering only DOM data, only PPC data, and a combination of both. A recursive feature elimination (RFE) method using a random forest was used for variable selection. Four different machine-learning (ML) algorithms (random forest, k-nearest neighbor, Cubist and supporting vector machine) were used to build regression models. Experimental results showed that PPC data alone could estimate AGB, and DOM data alone could estimate LAI with relatively high accuracy. The combination of features from DOM and PPC data was the most effective, in all the experiments considered, for the estimation of AGB and LAI. The results showed that the height and coverage variables of PPC, texture mean value, and the visible differential vegetation index (VDVI) of the DOM are significantly related to the estimated AGB (R2 = 0.73, RMSE = 20 t/ha). The results also showed that the canopy cover of PPC and green red ratio index (GRRI) of DOM are the most strongly related to the estimated LAI, and the height and coverage variables of PPC, the texture mean value and visible atmospherically resistant index (VARI), and the VDVI of DOM followed (R2 = 0.79, RMSE = 0.48). Full article
(This article belongs to the Special Issue Remote Sensing of Leaf Area Index (LAI) and Other Vegetation Parameters)
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15 pages, 3040 KiB  
Article
Predicting Growing Stock Volume of Scots Pine Stands Using Sentinel-2 Satellite Imagery and Airborne Image-Derived Point Clouds
by Paweł Hawryło and Piotr Wężyk
Forests 2018, 9(5), 274; https://doi.org/10.3390/f9050274 - 17 May 2018
Cited by 28 | Viewed by 4180
Abstract
Estimation of forest stand parameters using remotely sensed data has considerable significance for sustainable forest management. Wide and free access to the collection of medium-resolution optical multispectral Sentinel-2 satellite images is very important for the practical application of remote sensing technology in forestry. [...] Read more.
Estimation of forest stand parameters using remotely sensed data has considerable significance for sustainable forest management. Wide and free access to the collection of medium-resolution optical multispectral Sentinel-2 satellite images is very important for the practical application of remote sensing technology in forestry. This study assessed the accuracy of Sentinel-2-based growing stock volume predictive models of single canopy layer Scots pine (Pinus sylvestris L.) stands. We also investigated whether the inclusion of Sentinel-2 data improved the accuracy of models based on airborne image-derived point cloud data (IPC). A multiple linear regression (LM) and random forest (RF) methods were tested for generating predictive models. The measurements from 94 circular field plots (400 m2) were used as reference data. In general, the LM method provided more accurate models than the RF method. Models created using only Sentinel-2A images had low prediction accuracy and were characterized by a high root mean square error (RMSE%) of 35.14% and a low coefficient of determination (R2) of 0.24. Fusion of IPC data with Sentinel-2 reflectance values provided the most accurate model: RMSE% = 16.95% and R2 = 0.82. However, comparable accuracy was obtained using the IPC-based model: RMSE% = 17.26% and R2 = 0.81. The results showed that for single canopy layer Scots pine dominated stands the incorporation of Sentinel-2 satellite images into IPC-based growing stock volume predictive models did not significantly improve the model accuracy. From an operational point of view, the additional utilization of Sentinel-2 data is not justified in this context. Full article
(This article belongs to the Section Forest Inventory, Modeling and Remote Sensing)
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8 pages, 1583 KiB  
Article
Biophysical Factors Affecting Forest Cover Changes in Community Forestry: A Country Scale Analysis in Cambodia
by Pichdara Lonn, Nobuya Mizoue, Tetsuji Ota, Tsuyoshi Kajisa and Shigejiro Yoshida
Forests 2018, 9(5), 273; https://doi.org/10.3390/f9050273 - 17 May 2018
Cited by 12 | Viewed by 4261
Abstract
Community forestry (CF) is increasingly used in developing countries to achieve both the socioeconomic outcome of poverty reduction and an ecological outcome. There have been many single case studies in a specific region to identify the factors affecting the success or failure of [...] Read more.
Community forestry (CF) is increasingly used in developing countries to achieve both the socioeconomic outcome of poverty reduction and an ecological outcome. There have been many single case studies in a specific region to identify the factors affecting the success or failure of CF. Other studies have used large-N data collected from multiple countries. However, there is a dearth of large-N studies within a single country. In this study, we used a country scale dataset of 197 CF projects, established between 1994 and 2005 across Cambodia, to identify the biophysical factors that affected forest cover changes from 2005 to 2016. A mixed-effects logistic regression model was used for a total of 71,252 randomly sampled data pixels nested in the 197 CF. Results showed that deforestation in CF was likely to increase with increasing size of CF area at lower elevations and on gentler slopes. Deforestation also increased if CF was located close to villages, markets and CF boundaries, but further away from main roads. These findings on biophysical factors can help the government to decide on priority locations for further conservation interventions or for the establishment of new CF projects. Full article
(This article belongs to the Section Forest Ecology and Management)
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18 pages, 3543 KiB  
Article
Spatio-Temporal Patterns of Urban Forest Basal Area under China’s Rapid Urban Expansion and Greening: Implications for Urban Green Infrastructure Management
by Zhibin Ren, Xingyuan He, Haifeng Zheng and Hongxu Wei
Forests 2018, 9(5), 272; https://doi.org/10.3390/f9050272 - 17 May 2018
Cited by 8 | Viewed by 4409 | Retraction
Abstract
Urban forest (UF) basal area is an important parameter of UF structures, which can influence the functions of the UF ecosystem. However, the spatio-temporal pattern of the basal area in a given UF in regions under rapid urbanization and greening is still not [...] Read more.
Urban forest (UF) basal area is an important parameter of UF structures, which can influence the functions of the UF ecosystem. However, the spatio-temporal pattern of the basal area in a given UF in regions under rapid urbanization and greening is still not well documented. Our study explores the potential of estimating spatio-temporal UF basal area by using Thematic Mapper (TM) imagery. In our study, the predicting model was established to produce spatiotemporal maps of the urban forest basal area index in Changchun, China for the years 1984, 1995, 2005, and 2014. Our results showed that urban forests became more and more fragmented due to rapid urbanization from 1984 to 1995. Along with rapid urban greening after 1995, urban forest patches became larger and larger, creating a more homogeneous landscape. Urban forest and its basal area in the whole study area increased gradually from 1984 to 2014, especially in the outer belts of the city with urban sprawl. UF basal area was 27.3 × 103 m2, 41.3 × 103 m2, 45.8 × 103 m2, and 65.1 × 103 m2 of the entire study area for the year 1984, 1995, 2005, and 2014, respectively. The class distribution of the UF basal area index was skewed toward low values across all four years. In contrast, the frequency of a higher UF basal area index increased gradually from 1984 to 2014. Besides, the UF basal area index showed a decreasing trend along the gradient from suburban areas to urban center areas. Our results demonstrate the capability of TM remote sensing for understanding spatio-temporal changing patterns of UF basal area under China’s rapid urban expansion and greening. Full article
(This article belongs to the Special Issue Growth and Ecosystem Services of Urban Trees)
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21 pages, 15474 KiB  
Article
How Forest Gap and Elevation Shaped Abies faxoniana Rehd. et Wils. Regeneration in a Subalpine Coniferous Forest, Southwestern China
by Li Chen, Guohua Liu and Dan Liu
Forests 2018, 9(5), 271; https://doi.org/10.3390/f9050271 - 16 May 2018
Cited by 5 | Viewed by 3271
Abstract
Focusing on the underlying ecological mechanisms of dominant species regeneration in forest gaps at a landscape scale can provide detailed understanding for gap-based forest management. The individual effects of forest gaps or elevation on the regeneration of Abies faxoniana Rehd. et Wils. are [...] Read more.
Focusing on the underlying ecological mechanisms of dominant species regeneration in forest gaps at a landscape scale can provide detailed understanding for gap-based forest management. The individual effects of forest gaps or elevation on the regeneration of Abies faxoniana Rehd. et Wils. are well known, although elucidating how gap characteristics and elevation concurrently influence regeneration remains an important challenge. In this paper, we present an explorative study using structural equation models (SEMs) to assess the direct and indirect effects of forest gaps and elevation on Abies faxoniana Rehd. et Wils. regeneration. Four of the predicted SEMs showed the following results: (1) Temperature, photosynthetic photon flux density (PPFD), soil total carbon, gap openness, shrub layer cover, herb layer cover, and moss layer thickness in forest gaps were associated with Abies faxoniana regeneration along an elevation gradient in subalpine coniferous forest. (2) Elevation had a generally negative and indirect effect on Abies faxoniana regeneration. Forest gaps positively affected regeneration when compared with non-gap plots and gap size was positively related to small tree regeneration density and the ratio of height to diameter at breast height (HD ratio) of the tallest Abies faxoniana small trees but was negatively related to Abies faxoniana sapling regeneration density. (3) In forest gaps, the Abies faxoniana sapling density and HD ratio of the tallest Abies faxoniana small trees were mainly indirectly influenced by elevation, and Abies faxoniana small tree regeneration density was directly associated with the dominance of the sapling regeneration density. In summary, Abies faxoniana regeneration was negatively and largely affected by elevation (total effect), although forest gaps enhanced Abies faxoniana regeneration by multiple pathways (direct and indirect effects). Full article
(This article belongs to the Section Forest Ecology and Management)
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12 pages, 1547 KiB  
Article
Building Resistance and Resilience: Regeneration Should Not be Left to Chance
by James N. Long, Marcella Windmuller-Campione and R. Justin DeRose
Forests 2018, 9(5), 270; https://doi.org/10.3390/f9050270 - 16 May 2018
Cited by 13 | Viewed by 3912
Abstract
Contemporary forest planning has tasked managers with developing goals associated with resistance and resilience. In practice, silviculturists use forest structure and tree species composition to characterize goals and desired future conditions, write prescriptions, and monitor outcomes associated with resistance and resilience. Although rarely [...] Read more.
Contemporary forest planning has tasked managers with developing goals associated with resistance and resilience. In practice, silviculturists use forest structure and tree species composition to characterize goals and desired future conditions, write prescriptions, and monitor outcomes associated with resistance and resilience. Although rarely discussed in the exploding literature relating to forest resistance and resilience, silvicultural regeneration methods are important and underutilized tools to meet these goals. We propose alternative silvicultural systems for building resistance and resilience to two common large-scale bark beetle disturbance agents in the Intermountain West, United States: mountain pine beetle (Dendroctonus ponderosae Hopkins) and spruce beetle (Dendroctonus rufipennis Kirby). Shelterwood, and shelterwood-with-reserves, silvicultural systems provide the desirable facilitative characteristics of a mature overstory on maintaining advance reproduction and the establishment of new cohorts of desirable tree species. These also allow the timely regeneration of large treatment areas necessary to rapidly promote desired future conditions in the face of inevitable disturbance. When implemented proactively, regeneration treatments allow silviculturists to take advantage of currently existing vegetation for the creation of age class and tree species diversity. In general, these examples illustrate the need for proactive planning for regeneration in response to any disturbance where desired future conditions include particular species. Furthermore, we argue that timely silvicultural interventions that focus on regenerating trees may be a key factor in achieving goals relating to resilience to specific disturbance types. Waiting until after the disturbance has occurred could result in the lost opportunity to establish desired species composition or stand structure—and may well result in a considerable restoration challenge. Full article
(This article belongs to the Special Issue The Forest Renewal Issue: New Problems and Findings in the Establishment of Tree Regeneration)
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16 pages, 3981 KiB  
Article
Detecting and Attributing Drivers of Forest Disturbance in the Colombian Andes Using Landsat Time-Series
by Paulo J. Murillo-Sandoval, Thomas Hilker, Meg A. Krawchuk and Jamon Van Den Hoek
Forests 2018, 9(5), 269; https://doi.org/10.3390/f9050269 - 15 May 2018
Cited by 25 | Viewed by 5850
Abstract
The Colombian Andes foothills have seen an expansion of forest disturbance since the 1950s. While understanding the drivers of disturbance is important for quantifying the implications of land use change on regional biodiversity, methods for attributing disturbance to specific drivers of change at [...] Read more.
The Colombian Andes foothills have seen an expansion of forest disturbance since the 1950s. While understanding the drivers of disturbance is important for quantifying the implications of land use change on regional biodiversity, methods for attributing disturbance to specific drivers of change at a high temporal and spatial resolution are still lacking in the Andes region, in part due to persistent cloud cover. Using 20 years of Landsat images (1996–2015) covering Picachos National Park in the Colombian Andes, we detected sub-annual forest cover disturbances using the Breaks For Additive Season and Trend (BFAST) Monitor algorithm; characterized different types of disturbance using spectral, spatial, and topographic indicators; and attributed causes of forest disturbance such as conversion to pasture, conversion to agriculture, and non-stand replacing disturbance (i.e., thinning) using a Random Forest (RF) classifier. Conversion to pasture has been the main driver of forest disturbance in Picachos, responsible for 11,395 ± 72 ha (17%) of forest cover loss, followed by non-stand replacing disturbance and conversion to agriculture. Disturbance detection had 96% overall agreement with validation data, although we had a high omission error of 21% primarily associated with forest to agriculture conversion. Other change drivers had a much more reliable attribution with forest to pasture conversion or non-stand-replacing disturbance, showing only 1–5% commission and 2–14% omission errors. Our results provide spatially-explicit information on sub-annual disturbances and associated drivers of change that are necessary for evaluating and improving domestic conservation efforts and establishing systematic ecological observations, which is currently absent from Colombia. While effective at revealing forest change dynamics in a geographically remote and socio-politically complex region like Picachos, our approach is highly automated and it can be easily extended to the rest of Andes-Amazon transition belt where low availability of remote sensing data and high cloud cover impede efforts at consistent monitoring of forest cover change dynamics and drivers. Full article
(This article belongs to the Special Issue Mapping Forest Health Using Moderate Resolution Satellites)
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16 pages, 4348 KiB  
Article
Machine Learning Approaches for Estimating Forest Stand Height Using Plot-Based Observations and Airborne LiDAR Data
by Junghee Lee, Jungho Im, Kyungmin Kim and Lindi J. Quackenbush
Forests 2018, 9(5), 268; https://doi.org/10.3390/f9050268 - 14 May 2018
Cited by 39 | Viewed by 6151
Abstract
Effective sustainable forest management for broad areas needs consistent country-wide forest inventory data. A stand-level inventory is appropriate as a minimum unit for local and regional forest management. South Korea currently produces a forest type map that contains only four categorical parameters. Stand [...] Read more.
Effective sustainable forest management for broad areas needs consistent country-wide forest inventory data. A stand-level inventory is appropriate as a minimum unit for local and regional forest management. South Korea currently produces a forest type map that contains only four categorical parameters. Stand height is a crucial forest attribute for understanding forest ecosystems that is currently missing and should be included in future forest type maps. Estimation of forest stand height is challenging in South Korea because stands exist in small and irregular patches on highly rugged terrain. In this study, we proposed stand height estimation models suitable for rugged terrain with highly mixed tree species. An arithmetic mean height was used as a target variable. Plot-level height estimation models were first developed using 20 descriptive statistics from airborne Light Detection and Ranging (LiDAR) data and three machine learning approaches—support vector regression (SVR), modified regression trees (RT) and random forest (RF). Two schemes (i.e., central plot-based (Scheme 1) and stand-based (Scheme 2)) for expanding from the plot level to the stand level were then investigated. The results showed varied performance metrics (i.e., coefficient of determination, root mean square error, and mean bias) by model for forest height estimation at the plot level. There was no statistically significant difference among the three mean plot height models (i.e., SVR, RT and RF) in terms of estimated heights and bias (p-values > 0.05). The stand-level validation based on all tree measurements for three selected stands produced varied results by scheme and machine learning used. It implies that additional reference data should be used for a more thorough stand-level validation to identify statistically robust approaches in the future. Nonetheless, the research findings from this study can be used as a guide for estimating stand heights for forests in rugged terrain and with complex composition of tree species. Full article
(This article belongs to the Section Forest Inventory, Modeling and Remote Sensing)
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30 pages, 10463 KiB  
Article
Climate Change-Induced Shift of Tree Growth Sensitivity at a Central Himalayan Treeline Ecotone
by Niels Schwab, Ryszard J. Kaczka, Karolina Janecka, Jürgen Böhner, Ram P. Chaudhary, Thomas Scholten and Udo Schickhoff
Forests 2018, 9(5), 267; https://doi.org/10.3390/f9050267 - 13 May 2018
Cited by 41 | Viewed by 7126
Abstract
Himalayan treelines are exposed to above average climate change impact, resulting in complex tree growth–climate relationships for Himalayan Silver Fir (Abies spectabilis (D. Don) Spach) at central Himalayan treelines. The majority of recent studies detected current tree growth sensitivity to dry conditions [...] Read more.
Himalayan treelines are exposed to above average climate change impact, resulting in complex tree growth–climate relationships for Himalayan Silver Fir (Abies spectabilis (D. Don) Spach) at central Himalayan treelines. The majority of recent studies detected current tree growth sensitivity to dry conditions during pre-monsoon seasons. The aim of this study was to analyze growth–climate relationships for more than a century for a treeline ecotone in east-central Nepal and to test for Blue Intensity (BI; used as a surrogate of maximum late wood density) as climate proxy. We determined the relationships of Abies spectabilis radial tree growth and BI to climate by correlating both to temperature, precipitation and drought index data. The results showed a significantly unstable dendroclimatic signal over time. Climate warming-induced moisture deficits during pre-monsoon seasons became a major factor limiting radial tree growth during recent decades. Earlier in time, the dendroclimatic signal was weaker, predominantly reflecting a positive relationship of tree growth and summer temperature. Compared to radial tree growth, BI showed a different but strong climate signal. Temporally unstable correlations may be attributed to increasing effects of above-average rates of climate warming. An extended network of Himalayan tree-ring sites is needed to further analyze cause–effect relationships and to solve this attribution problem. Full article
(This article belongs to the Special Issue Tree-Ring Records of Climatic Impacts on Forests)
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21 pages, 2519 KiB  
Article
Recruitment Niches of Enterolobium contortisiliquum (Vell.) Morong: Functional Acclimations to Light
by Vicente Luiz Naves, Serge Rambal, João Paulo R. A. D. Barbosa, Evaristo Mauro de Castro and Moacir Pasqual
Forests 2018, 9(5), 266; https://doi.org/10.3390/f9050266 - 13 May 2018
Cited by 2 | Viewed by 3812
Abstract
Adjustments that a tree species displays in acclimating to light conditions may explain its fate in different forest successional stages. Enterolobium contortisiliquum (Vell.) Morong is a tree found in contrasting light environments and used in reforestation programs because of its rapid growth. This [...] Read more.
Adjustments that a tree species displays in acclimating to light conditions may explain its fate in different forest successional stages. Enterolobium contortisiliquum (Vell.) Morong is a tree found in contrasting light environments and used in reforestation programs because of its rapid growth. This study analyzed the performance of tamboril seedlings grown in three light environments: FS—full sun (100% of photosynthetically active radiation (PAR) and a red/far-red ratio (R/FR) of 1.66), S—shade net (38% of PAR and a R/FR of 1.54) and I—Insulfilm® (Insulfilm, São Paulo, Brazil) shade cloth (24% of PAR and a R/FR of 0.69). Greater net assimilation, higher root/shoot ratio, higher stomatal density, and reduced leaf area are some of the functional traits developed by tamboril to acclimate to full sun. On the other hand, a larger leaf area associated with a greater specific leaf area, higher leaf area ratio, higher leaf number and leafing intensity, as well as higher chlorophyll and carotenoid contents are among the most important traits for tamboril to acclimate to shade. The seedlings growing in FS displayed the best quality index. However, the traits developed in the nursery under each light condition could promote the successful installation and survival of tamboril seedlings under similar conditions in the field. Full article
(This article belongs to the Section Forest Ecophysiology and Biology)
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16 pages, 5594 KiB  
Article
Quantitative Spatiotemporal Oil Body Ultrastructure Helps to Verify the Distinct Lipid Deposition Patterns in Benzoin Endosperm and Embryo Cells
by Zihan Zhang, Ying Luo, Xiaojun Wang and Fangyuan Yu
Forests 2018, 9(5), 265; https://doi.org/10.3390/f9050265 - 12 May 2018
Cited by 13 | Viewed by 3115
Abstract
Seed oil content is an important characteristic for the potential biofuel feedstock benzoin (Styrax tonkinensis). With the aim of further understanding benzoin lipid biosynthesis, the endosperm and embryo cell ultrastructures were acquired through transmission electron microscopy (TEM); the relative oil body [...] Read more.
Seed oil content is an important characteristic for the potential biofuel feedstock benzoin (Styrax tonkinensis). With the aim of further understanding benzoin lipid biosynthesis, the endosperm and embryo cell ultrastructures were acquired through transmission electron microscopy (TEM); the relative oil body area per cell (ROA) and oil body diameter (OBD) were then calculated by analyzing TEM images via computer software. The endosperm ROA peaked at 99 days after flowering (DAF) (79.04%), and the embryo ROA dynamic fitted the “S” curve. Significant linear relations (p < 0.01) were only observed between endosperm ROAs and the contents of whole-kernel crude lipid and fatty acids. The endosperm OBD (1.18–2.43 μm) was larger than that of embryo OBD (0.38–0.77 μm). M-shaped dynamics of acetyl coenzyme carboxylase (ACC) and diglyceride acyltransferase (DGAT) activities resembled the dynamic of endosperm OBD, as two peaks were observed at 78 and 113 DAF; the big oil body (≥1.8 μm) fraction in endosperm increased as kernel ACC and DGAT activities also increased, and vice-versa. Embryo OBD gradually increased, with the big oil body (≥0.5 μm) proportion increasing and the small oil body (<0.5 μm) proportion decreasing in general. Our results collectively suggested the distinct lipid accumulation patterns in the two benzoin kernel tissues, and revealed that the endosperm may determine the whole kernel oil biosynthetic process. Full article
(This article belongs to the Section Forest Ecophysiology and Biology)
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22 pages, 1289 KiB  
Review
Socioeconomic Constraints to Biomass Removal from Forest Lands for Fire Risk Reduction in the Western U.S.
by David L. Nicholls, Jeffrey M. Halbrook, Michelle E. Benedum, Han-Sup Han, Eini C. Lowell, Dennis R. Becker and R. James Barbour
Forests 2018, 9(5), 264; https://doi.org/10.3390/f9050264 - 11 May 2018
Cited by 25 | Viewed by 4950
Abstract
Many socioeconomic constraints exist for biomass removals from federal lands in the western U.S. We examine several issues of importance, including biomass supply chains and harvesting costs, innovative new uses for bioenergy products, and the policy framework in place to provide incentives for [...] Read more.
Many socioeconomic constraints exist for biomass removals from federal lands in the western U.S. We examine several issues of importance, including biomass supply chains and harvesting costs, innovative new uses for bioenergy products, and the policy framework in place to provide incentives for biomass use. Western states vary greatly in the extent and utilization of forest resources, the proportion of land under federal ownership, and community and stakeholder structure and dynamics. Our research—which focused on the socioeconomic factors associated with biomass removal, production, and use—identified several important trends. Long-term stewardship projects could play a role in influencing project economics while being conducive to private investment. State policies are likely to help guide the growth of biomass utilization for energy products. New markets and technologies, such as biofuels, for use in the aviation industry, torrefied wood, mobile pyrolysis, and wood coal cofiring could greatly change the landscape of biomass use. Social needs of residents in wildland urban interfaces will play an important role, especially in an era of megafires. All of these trends—including significant unknowns, like the volatile prices of fossil energy—are likely to affect the economics of biomass removal and use in western forests. Full article
(This article belongs to the Special Issue At the Frontiers of Knowledge in Forest Economics)
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12 pages, 2789 KiB  
Article
High Mortality and Low Net Change in Live Woody Biomass of Karst Evergreen and Deciduous Broad-Leaved Mixed Forest in Southwestern China
by Libin Liu, Jian Ni, Qiaolian Zhong, Gang Hu and Zhonghua Zhang
Forests 2018, 9(5), 263; https://doi.org/10.3390/f9050263 - 11 May 2018
Cited by 19 | Viewed by 3758
Abstract
Repeated observation based on large permanent monitoring plots is a key method for directly understanding forest regeneration dynamics. Karst forests grow slowly in adverse habitats and possess a special regeneration mode. However, no data can support these properties because no repeated observations have [...] Read more.
Repeated observation based on large permanent monitoring plots is a key method for directly understanding forest regeneration dynamics. Karst forests grow slowly in adverse habitats and possess a special regeneration mode. However, no data can support these properties because no repeated observations have been performed. The mortality, recruitment, and net change in live woody biomass (NPPlw) of a karst evergreen and deciduous broad-leaved mixed forest in Central Guizhou Province, Southwestern China, were studied on the basis of a short-term continuous monitoring (3 years) of a 2 ha plot. The species richness of individuals with a diameter at breast height (DBH) ≥ 1 cm decreased from 66 to 58 during the study period. Eight species disappeared, and no new species appeared. The individual number declined from 16,821 to 15,003 because most species indicated more deaths than recruitments. Trees presented the lowest mortality rate, and shrubs presented the highest recruitment rate among the species. Individual death number decreased with the increase in DBH classes. The estimated aboveground NPPlw was 8.41 t ha−1 year−1. The survivors, recruitments, and deaths contributed 10.88, 0.11, and −2.58 t ha−1 year−1, respectively. Trees (8.37 t ha−1 year−1), rather than shrubs (0.04 t ha−1 year−1) and lianas (−0.004 t ha−1 year−1), were the major contributors. The karst forest presented higher mortality and lower NPPlw than nonkarst forests in subtropical China and in the world. Full article
(This article belongs to the Special Issue Disturbance, Succession, and Development of Forests)
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19 pages, 2044 KiB  
Article
Effects of Increased Soil Scarification Intensity on Natural Regeneration of Scots Pine Pinus sylvestris L. and Birch Betula spp. L.
by Mona Saursaunet, Karen Marie Mathisen and Christina Skarpe
Forests 2018, 9(5), 262; https://doi.org/10.3390/f9050262 - 11 May 2018
Cited by 16 | Viewed by 4044
Abstract
Achieving an optimal density of trees is essential for the final yield in commercial forestry. Soil scarification is commonly used in Scandinavia in order to produce successful regenerations of Scots pine (Pinus sylvestris L.), especially in areas with risk of browsing damage [...] Read more.
Achieving an optimal density of trees is essential for the final yield in commercial forestry. Soil scarification is commonly used in Scandinavia in order to produce successful regenerations of Scots pine (Pinus sylvestris L.), especially in areas with risk of browsing damage by moose (Alces alces L.). The research presented in this paper provides knowledge on how increased intensity of soil scarification affects the regeneration of pine and birch (Betula spp. L.). A total of 67 stands were treated with different intensities of soil scarification. Tree seedling density and current annual growth (CAG) were measured one to five years after scarification. Results showed that the density of pine and birch seedlings increased with soil scarification intensity. CAG of pine decreased with scarification intensity. CAG of downy birch decreased with proportion of exposed mineral soil, but increased with proportion of exposed humus. The effect of soil scarification intensity on CAG of both tree species was relatively weak. Results suggest that although increased scarification intensity had a positive effect on seedling establishment, the effect on early growth may be unfavourable. Further research is needed in order to evaluate the long-term effects of soil scarification intensity on growth. Full article
(This article belongs to the Section Forest Ecology and Management)
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24 pages, 3085 KiB  
Article
Additive Biomass Equations Based on Different Dendrometric Variables for Two Dominant Species (Larix gmelini Rupr. and Betula platyphylla Suk.) in Natural Forests in the Eastern Daxing’an Mountains, Northeast China
by Lihu Dong, Lianjun Zhang and Fengri Li
Forests 2018, 9(5), 261; https://doi.org/10.3390/f9050261 - 10 May 2018
Cited by 45 | Viewed by 3970
Abstract
A total of 138 Dahurian larch (Larix gmelinii Rupr.) trees and 108 white birch (Betula platyphylla Suk.) trees were harvested in the eastern Daxing’an Mountains, northeast China. We developed four additive systems of biomass equations as follows: the first additive model [...] Read more.
A total of 138 Dahurian larch (Larix gmelinii Rupr.) trees and 108 white birch (Betula platyphylla Suk.) trees were harvested in the eastern Daxing’an Mountains, northeast China. We developed four additive systems of biomass equations as follows: the first additive model system (MS-1) used the best combination of tree variables as the predictors; the second additive model system (MS-2) included tree diameter at breast height (D) as the sole predictor; the third additive model system (MS-3) included both D and tree height (H) as the predictors; and the fourth additive model system (MS-4) included D, H, and crown attributes (crown width (CW) and crown length (CL)) as the predictors. The model coefficients were simultaneously estimated using seemingly unrelated regression (SUR). The heteroscedasticity in model residuals was addressed by applying a unique weight function to each equation. The results indicated that: (1) the stem biomass accounted for the largest proportion of the total tree biomass, while the foliage biomass had the smallest proportion for the two species; (2) the four additive systems of biomass equations exhibited good model fitting and prediction performance, of which the model Ra2 > 0.81, the mean prediction error (MPE) was close to 0, and the mean absolute error (MAE) was relatively small (<9 kg); (3) MS-1 and MS-4 significantly improved the model fitting and performance; the ranking of the four additive systems followed the order of MS-1 > MS-4 > MS-3 > MS-2. Overall, the four additive systems can be applied to estimate individual tree biomass of both species in the Chinese National Forest Inventory. Full article
(This article belongs to the Section Forest Ecology and Management)
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14 pages, 3896 KiB  
Article
Fog Water Is Important in Maintaining the Water Budgets of Vascular Epiphytes in an Asian Tropical Karst Forests during the Dry Season
by Yi Wu, Liang Song, Wenyao Liu, Wenjie Liu, Su Li, Peili Fu, Youxin Shen, Junen Wu, Pingyuan Wang, Quan Chen and Huazheng Lu
Forests 2018, 9(5), 260; https://doi.org/10.3390/f9050260 - 10 May 2018
Cited by 16 | Viewed by 4740
Abstract
Fog may be an important source of water for forest vascular epiphytes on trees, because they lack direct access to sources of soil water, but little is known about the water use proportions from various sources and potential water uptake pathways in epiphytes. [...] Read more.
Fog may be an important source of water for forest vascular epiphytes on trees, because they lack direct access to sources of soil water, but little is known about the water use proportions from various sources and potential water uptake pathways in epiphytes. Here, we analyzed leaf carbon isotope ratios as a measure of water use efficiency (WUE), proportions of fog, rain, and soil water use, and foliar water uptake (FWU) in species of epiphyte and their host trees in a tropical karst dwarf forest in China during the dry season. We found that the WUE, as represented by leaf δ13C, was generally enriched in the epiphyte species compared to their host trees. Epiphytes used substantial proportions of fog water, whereas water use in the host trees was dominated by soil water. The leaves of epiphytes and host trees absorbed water following immersion in water for 3 h and FWU possibly related to foliar epicuticular structures, such as fungal endophytes. Our results show a divergence of water use strategies between epiphytes and their hosts and highlight the importance of fog water for epiphytes during the dry season and under a climate change scenario with a reduced occurrence of fog events. Full article
(This article belongs to the Section Forest Ecology and Management)
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16 pages, 5876 KiB  
Article
Assessing Climate Change Impact on Forest Habitat Suitability and Diversity in the Korean Peninsula
by Chul-Hee Lim, Somin Yoo, Yuyoung Choi, Seong Woo Jeon, Yowhan Son and Woo-Kyun Lee
Forests 2018, 9(5), 259; https://doi.org/10.3390/f9050259 - 10 May 2018
Cited by 29 | Viewed by 5979
Abstract
Habitat changes in temperate forests are more vulnerable to climate change than tropical or boreal forests. This study assessed forest habitat suitability and diversity to determine the impact of climate change on the Korean Peninsula. We used the MaxEnt (Maximum Entropy) species distribution [...] Read more.
Habitat changes in temperate forests are more vulnerable to climate change than tropical or boreal forests. This study assessed forest habitat suitability and diversity to determine the impact of climate change on the Korean Peninsula. We used the MaxEnt (Maximum Entropy) species distribution model, three key climate indices, and two representative climate change scenarios, using short and long-term data. Two of the three key climate indices related to temperature were more capricious than the precipitation-related index in the future. In the baseline prediction, both statistical and qualitative validation using the actual vegetation map showed excellent results. Regarding forest habitat suitability, northward migration and substantial increase were definitely distinctive in warm temperate evergreen forest. On the other hand, subalpine forest areas decreased significantly due to climate change; the suitable area for Representative Concentration Pathways (RCP) 8.5 2070s decreased by more than half. With regard to forest habitat diversity, regions with high diversity declined due to climate change. In the RCP 8.5 scenario, areas where all three forest types are suitable no longer appeared; however, in the case of RCP 4.5 2050s, suitable areas for two forest types increased, which implies climate change is not only negative in terms of diversity. As this negative prediction of future change is discouraging, active mitigation and adaptation are required to prevent these changes. The sustainability of future ecosystems is still dependent on our efforts. Full article
(This article belongs to the Special Issue Climate Smart Forestry)
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18 pages, 3692 KiB  
Article
Black Plastic Mulch or Herbicide to Accelerate Bur Oak, Black Walnut, and White Pine Growth in Agricultural Riparian Buffers?
by Benoit Truax, Julien Fortier, Daniel Gagnon and France Lambert
Forests 2018, 9(5), 258; https://doi.org/10.3390/f9050258 - 10 May 2018
Cited by 4 | Viewed by 4707
Abstract
This study was conducted in a riparian buffer bordering a 1 km segment of a headwater stream crossing a pasture site located in southern Québec (Canada). Three species were planted (black walnut (Juglans nigra L.), bur oak (Quercus macrocarpa Michx.), and [...] Read more.
This study was conducted in a riparian buffer bordering a 1 km segment of a headwater stream crossing a pasture site located in southern Québec (Canada). Three species were planted (black walnut (Juglans nigra L.), bur oak (Quercus macrocarpa Michx.), and eastern white pine (Pinus strobus L.)) with three vegetation treatments (control, herbicide (one application/year for 3 years), and black plastic mulch)). The main objective was to determine to which extent herbicide and plastic mulch, used with species having different ecological characteristics, affect tree growth and soil nutrient status in riparian buffers. Survival was high (>93%) for all species in all treatments. In the control (no vegetation treatment), growth was similar among species. Black walnut had the strongest growth response to herbicide and plastic mulch, and white pine had the weakest. For all species, growth was similar in the herbicide and the plastic mulch treatments. During the fifth growing season, plastic mulch increased soil nitrate and phosphorus compared to the herbicide treatment. In the plastic mulch treatment, higher soil nitrate supply was observed for species that preferentially uptake ammonium (black walnut and white pine). Soil nutrient supplies were similar between the control and herbicide treatments. Despite the more favorable nutritional conditions it provides, permanent black plastic mulching does not provide higher growth benefits after 5 years than a 3-year herbicide treatment. The high soil nitrate supply observed in mulched black walnut and mulched white pine may indicate a limited capacity for nitrate phytoremediation by these species. Full article
(This article belongs to the Special Issue Hardwood Reforestation and Restoration)
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17 pages, 3730 KiB  
Article
Corsican Pine (Pinus laricio Poiret) Stand Management: Medium and Long Lasting Effects of Thinning on Biomass Growth
by Rodolfo Picchio, Rachele Venanzi, Francesco Latterini, Enrico Marchi, Andrea Laschi and Angela Lo Monaco
Forests 2018, 9(5), 257; https://doi.org/10.3390/f9050257 - 10 May 2018
Cited by 16 | Viewed by 3931
Abstract
With the aim of acquiring better comprehension of the ecological and productive aspects of the management of pine forests, we monitored logging damage and evaluated the effects of thinning on stand growth 20 years after the treatment in a Pinus laricio Poiret stand [...] Read more.
With the aim of acquiring better comprehension of the ecological and productive aspects of the management of pine forests, we monitored logging damage and evaluated the effects of thinning on stand growth 20 years after the treatment in a Pinus laricio Poiret stand in central Italy. The objectives of the present study were to estimate the injury levels to the remaining trees after thinning; to assess logging damage in the long-term by monitoring residual trees at the end of thinning; to evaluate the effect of damage on the radial growth of trees; to assess the stand dynamics in relation to injury levels and the treatment applied in a twenty-year range; to understand a possible treatment return time; and to evaluate the existence of the “thinning shock”. The results were that 20 years after treatment, the stand dynamics showed a complete recovery; logging damage did not affect the radial growth of P. laricio over time; a second treatment seem to be sustainable starting from the fifteenth year after the previous treatment; and the thinning shock can be clearly evaluated in the first six to seven years after the treatment. Full article
(This article belongs to the Special Issue Ecological Management of Pine Forests)
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17 pages, 2983 KiB  
Article
Spruce Budworm (Choristoneura fumiferana Clem.) Defoliation Promotes Vertical Fuel Continuity in Ontario’s Boreal Mixedwood Forest
by Graham A. Watt, Richard A. Fleming, Sandy M. Smith and Marie-Josée Fortin
Forests 2018, 9(5), 256; https://doi.org/10.3390/f9050256 - 09 May 2018
Cited by 5 | Viewed by 4548
Abstract
Spruce budworm, Choristoneura fumiferana (Clem.), defoliation has been shown to affect the occurrence of crown fire in Ontario, highlighting the need to better understand the driving factors of this effect on forest structure, including changes in fuel loading, type and position. Here, we [...] Read more.
Spruce budworm, Choristoneura fumiferana (Clem.), defoliation has been shown to affect the occurrence of crown fire in Ontario, highlighting the need to better understand the driving factors of this effect on forest structure, including changes in fuel loading, type and position. Here, we investigate five boreal mixedwood sites within four zones that experienced different durations of continuous defoliation by spruce budworm in northeastern Ontario. Duration of defoliation had significant effects on vertical stand components, namely, host overstory to host understory crown overlap, host overstory and host understory crown to downed woody debris overlap, and downed woody debris height and quantity. Vertical stand components tended to increase with the duration of continuous defoliation, with the highest vertical fuel continuity occurring after 16 years of continuous defoliation. Such increases in the vertical spatial continuity of fuels may be a key reason for the greater percentage of area burned in those forests which have recently sustained a spruce budworm outbreak. Full article
(This article belongs to the Special Issue Wildland Fire, Forest Dynamics, and Their Interactions)
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13 pages, 1876 KiB  
Article
Perceptions on the Importance of Forest Sector Innovations: Biofuels, Biomaterials, or Niche Products?
by T. Stern, L. Ranacher, C. Mair, S. Berghäll, K. Lähtinen, M. Forsblom and A. Toppinen
Forests 2018, 9(5), 255; https://doi.org/10.3390/f9050255 - 08 May 2018
Cited by 25 | Viewed by 8131
Abstract
New innovations are called for to renew the European forest sector into bioeconomy. However, little research exists on how the industry innovativeness is publicly perceived. Using data collected with an online questionnaire in four European countries, we investigate perceptions related to forest sector [...] Read more.
New innovations are called for to renew the European forest sector into bioeconomy. However, little research exists on how the industry innovativeness is publicly perceived. Using data collected with an online questionnaire in four European countries, we investigate perceptions related to forest sector innovations on 13 current and new bioeconomy-related products and services. Altogether, 218 valid responses were received in 2015, and the data were analysed using descriptive statistics, performance-importance analysis, and Gartner’s innovation hype cycle. Based on our results, the respondents were in the strongest agreement that the forest sector has since the year 2000 has produced innovations related to wood building systems, construction materials, and wood composites. In the next 15 years, they foresaw a decline in innovations related to biofuels and paper products. The European forest sector also has future potential in wood construction, which is likely related to international policy targets related to carbon mitigation and capture. The observed variation in perceptions among the respondents on forest sector innovativeness calls for strengthening industry R&D, as well as by improving societal awareness of ongoing innovation projects by developing better communication. Full article
(This article belongs to the Special Issue Our Future Forests and Their Products—How to Get out of the Woods—Selected Papers from the IUFRO 125th Anniversary Congress)
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13 pages, 707 KiB  
Article
Forest Biomass Policy in Minnesota: Supply Chain Perspectives on Barriers to Bioenergy Development
by Laura Eaton Carleton and Dennis Becker
Forests 2018, 9(5), 254; https://doi.org/10.3390/f9050254 - 08 May 2018
Cited by 7 | Viewed by 3504
Abstract
Forest biomass used for heating, electricity, and biofuel production is a source of energy that could reduce the dependence on energy imports while reinvesting domestically. Using the appropriate scale and technology, the US state of Minnesota is poised for increased forest bioenergy production [...] Read more.
Forest biomass used for heating, electricity, and biofuel production is a source of energy that could reduce the dependence on energy imports while reinvesting domestically. Using the appropriate scale and technology, the US state of Minnesota is poised for increased forest bioenergy production due to the large existing forest products industry. Forest bioenergy investments have been slow to materialize despite state and federal incentives, and this research aims to determine what barriers there are to bioenergy development from the perspective of supply-chain actors by applying theories of natural resource governance. Findings from interviews include the need to create an equitable playing field in terms of energy subsidies and integrate forest bioenergy production with bio-based markets, including traditional forest product markets. Additionally, interviews indicate poor coordination and shared responsibility among state agencies, industry associations, and nonprofit organizations, resulting in a fragmented policy system. Principles to guide enabling forest bioenergy development are identified and discussed in the context of the study findings. Full article
(This article belongs to the Special Issue Forest Bioenergy and Bioproducts)
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