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Forests
Volume 9
Issue 8
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Forests, Volume 9, Issue 8 (August 2018) – 63 articles

Cover Story (view full-size image): Cover Image: Canopy traits are integral the study of trees and forest ecosystem function, but can be notoriously difficult to assess, often due to challenges inherent in reaching the treetops of established stands. Ecohydrology students at the University of Michigan Biological Station take advantage of a ‘zero-emissions’ battery operated canopy lift to assess physiological and morphological traits of leaves and branches in a 100 year old temperate deciduous forest. Trait observations like these are compiled across multiple ecosystems in the article “Plant Hydraulic Trait Covariation: A Global Meta-Analysis to Reduce Degrees of Freedom in Trait-Based Hydrologic Models.” The cross-trait relationships observed in this work can be used to simplify hydraulically based models of transpiration and root water uptake. While newly developed statistical models relating different trait combinations, or hydraulic [...] Read more.
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14 pages, 4399 KiB  
Article
Preferences for Urban Building Materials: Does Building Culture Background Matter? †
by Olav Høibø, Eric Hansen, Erlend Nybakk and Marius Nygaard
Forests 2018, 9(8), 504; https://doi.org/10.3390/f9080504 - 17 Aug 2018
Cited by 20 | Viewed by 6183
Abstract
A fast-growing global population, increasing urbanization, and an increasing flow of people with different building cultural backgrounds bring material use in the housing sector into focus. The aim of this study is to identify material preferences in the building environment in cities and [...] Read more.
A fast-growing global population, increasing urbanization, and an increasing flow of people with different building cultural backgrounds bring material use in the housing sector into focus. The aim of this study is to identify material preferences in the building environment in cities and to determine if the building cultural background impacts those preferences. The data in this study consisted of responses from two groups of dwellers in Norway, including immigrants from countries where wood is an uncommon building material and native Norwegians from a building culture where wood is common. We found that the most preferred materials were often the same as the most common materials currently used in city buildings. Only small differences were found between the two groups of dwellers that were studied. Most differences were related to concerns about material choice in general and where individuals wanted to live. Respondents who preferred city living preferred commonly used city materials, such as concrete and steel. For cladding materials, stone/bricks were the most preferred. However, stained or painted wood was one of the most preferred, even though it is not commonly used in city buildings. Full article
(This article belongs to the Special Issue Wood Properties and Processing)
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25 pages, 4955 KiB  
Article
Environmental, Structural, and Disturbance Influences over Forest Floor Components in Interior Douglas-Fir Forests of the Intermountain West, USA
by Andrew D. Giunta and John D. Shaw
Forests 2018, 9(8), 503; https://doi.org/10.3390/f9080503 - 17 Aug 2018
Viewed by 3866
Abstract
Downed woody material (DWM) is a key component in forest ecosystems with age, structure, and disturbance described as primary factors that influence DWM dynamics. In particular, much emphasis is placed on large coarse woody debris (CWD). Fine woody debris (FWD) (less than 7.62 [...] Read more.
Downed woody material (DWM) is a key component in forest ecosystems with age, structure, and disturbance described as primary factors that influence DWM dynamics. In particular, much emphasis is placed on large coarse woody debris (CWD). Fine woody debris (FWD) (less than 7.62 cm diameter), duff, and litter also contribute to carbon stocks, provide habitat, add to nutrient cycling, and are often the most available fuels for fire, yet are regularly overlooked in studies describing the forest floor. Throughout the middle montane zone within the Intermountain West region USA, interior Douglas-fir (Pseudotsuga menziesii var. glauca Mirb. Franco) is a predominant forest type, yet little is known about the forest floor complex in these forests. We used a chronosequence approach to compare DWM patterns over the course of stand development among stands with different disturbance histories. Using classification and regression trees, we also evaluated an assemblage of environmental, structural, and disturbance variables to determine factors of most importance for estimating loading for DWM, duff, and litter. We found CWD resembled a U-shaped pattern of buildup while FWD components remained stable over the course of stand development regardless of disturbance history. Our results indicate that large DWM components are most closely associated with the amount of standing dead material in a stand, primarily the density and basal area of snags. Fine woody material was more aligned with live stand components, while duff and litter were more influenced by disturbance. Full article
(This article belongs to the Special Issue Disturbance, Succession, and Development of Forests)
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11 pages, 713 KiB  
Article
Invasive-Plant-Removal Frequency—Its Impact on Species Spread and Implications for Further Integration of Forest-Management Practices
by Bernabas Wolde and Pankaj Lal
Forests 2018, 9(8), 502; https://doi.org/10.3390/f9080502 - 17 Aug 2018
Cited by 3 | Viewed by 3896
Abstract
For a given invasive plant species and control method, effective invasive plant eradication requires regular monitoring and management. While most previous studies characterize invasive plant species, develop appropriate control methods, or prioritize species for management using aggressiveness and other considerations, few study why [...] Read more.
For a given invasive plant species and control method, effective invasive plant eradication requires regular monitoring and management. While most previous studies characterize invasive plant species, develop appropriate control methods, or prioritize species for management using aggressiveness and other considerations, few study why some forestland owners are less likely than others to regularly remove invasive plant species. Such information is useful in prioritizing and targeting forestland owners who are at greater risk for invasion, with the stands threatening adjacent forestlands. Towards this end, we surveyed 1800 forestland owners in Virginia and Texas. We use data on forestland owners’ socioeconomics and forestland features—such as acreage, forestland ownership objectives, and forest management activities—to determine how these factors affect the regularity of invasive-plant removal. For these purposes, we used the Cochran–Armitage trend test, the Cochran–Mantel–Haenszal regression, odds ratio estimates, and partition-analysis techniques. Our results suggest that female forestland owners, owners with smaller forestlands, and forestland owners without written forest-management plans are less likely than others to regularly remove invasive plant species. Forest-management activities, such as building/maintaining roads in the forestland, partially harvesting stands, and wildlife- and fisheries-improvement projects, also significantly predict a more regular invasive-plant-removal tendency. However, since these activities are potential pathways for the spread of invasive plant species, we controlled for the other significant covariates and measured the relationship between frequent practice of the given forest-management activities and having a tendency to regularly remove invasive plant species. The results suggest that forestland owners that regularly practiced the said forest-management activities have higher odds for tending to remove invasive plant species regularly, suggesting that, despite their demonstrated effort at removing invasive plant species from their forest, their management activities may be inadvertently contributing to the spread of invasive plant species. These results highlight the importance of integrating invasive-plant-removal plans with forest-management plans as well as forestland owners’ educational and outreach needs. Full article
(This article belongs to the Special Issue Forest Bioenergy and Bioproducts)
13 pages, 3651 KiB  
Article
Determining Noise and Vibration Exposure in Conifer Cross-Cutting Operations by Using Li-Ion Batteries and Electric Chainsaws
by Francesco Neri, Andrea Laschi, Cristiano Foderi, Fabio Fabiano, Lucia Bertuzzi and Enrico Marchi
Forests 2018, 9(8), 501; https://doi.org/10.3390/f9080501 - 17 Aug 2018
Cited by 31 | Viewed by 5068
Abstract
In many activities, chainsaw users are exposed to the risk of injuries and several other hazard factors that may cause health problems. In fact, environmental and working conditions when using chainsaws result in workers’ exposure to hazards such as noise, vibration, exhaust gases, [...] Read more.
In many activities, chainsaw users are exposed to the risk of injuries and several other hazard factors that may cause health problems. In fact, environmental and working conditions when using chainsaws result in workers’ exposure to hazards such as noise, vibration, exhaust gases, and wood dust. Repeated or continuous exposure to these unfavourable conditions can lead to occupational diseases that become apparent after a certain period of time has elapsed. Since the use of electric tools is increasing in forestry, the present research aims to evaluate the noise and vibration exposure caused by four models of electric chainsaws (Stihl MSA160T, Stihl MSA200C Li-Ion battery powered and Stihl MSE180C, Stihl MSE220C wired) during cross-cutting. Values measured on the Stihl MSA160T chainsaw (Li-Ion battery) showed similar vibration levels on both right and left handles (0.9–1.0 m s−2, respectively) and so did the other battery-powered chainsaw, the Stihl MSA200C (2.2–2.3 m s−2 for right and left handles, respectively). Results showed a range of noise included between 81 and 90 dB(A) for the analysed chainsaws. In conclusion, the vibrations and noise were lower for the battery chainsaws than the wired ones, but, in general, all the values were lower than those measured in previous studies of endothermic chainsaws. Full article
(This article belongs to the Special Issue Forest Operations: Planning, Innovation and Sustainability)
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11 pages, 3016 KiB  
Article
Taylor’s Power Law for Leaf Bilateral Symmetry
by Ping Wang, David A. Ratkowsky, Xiao Xiao, Xiaojing Yu, Jialu Su, Lifang Zhang and Peijian Shi
Forests 2018, 9(8), 500; https://doi.org/10.3390/f9080500 - 16 Aug 2018
Cited by 20 | Viewed by 3531
Abstract
Leaf shape and symmetry is of interest because of the importance of leaves in photosynthesis. Recently, a novel method was proposed to measure the extent of bilateral symmetry in leaves in which a leaf was divided into left and right sides by a [...] Read more.
Leaf shape and symmetry is of interest because of the importance of leaves in photosynthesis. Recently, a novel method was proposed to measure the extent of bilateral symmetry in leaves in which a leaf was divided into left and right sides by a straight line through the leaf apex and base, and a number of equidistant strips were drawn perpendicular to the straight line to generate an equivalent number of differences in area between the left and right parts. These areal differences are the basis for a measure of leaf bilateral symmetry, which was then examined to see how well it follows Taylor’s power law (TPL) using three classes of plants, namely, 10 geographical populations of Parrotia subaequalis (H.T. Chang) R.M. Hao et H.T. Wei, 10 species of Bambusoideae, and 10 species of Rosaceae. The measure of bilateral symmetry followed TPL for a single species or for a class of closely related species. The estimate of the exponent of TPL for bamboo plants was significantly larger than for the dicotyledonous trees, but its goodness of fit was the best among the three classes of plants. The heterogeneity of light falling on branches and leaves due to above-ground architectural patterns is an important contributor to leaf asymmetry. Full article
(This article belongs to the Section Forest Ecophysiology and Biology)
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24 pages, 5148 KiB  
Article
Ecological Factors Affecting White Pine, Red Oak, Bitternut Hickory and Black Walnut Underplanting Success in a Northern Temperate Post-Agricultural Forest
by Benoit Truax, Daniel Gagnon, Julien Fortier, France Lambert and Marc-Antoine Pétrin
Forests 2018, 9(8), 499; https://doi.org/10.3390/f9080499 - 16 Aug 2018
Cited by 12 | Viewed by 6306
Abstract
This study took place in southern Québec (Canada) where young stands of white ash and grey birch have been underplanted with white pine, red oak, bitternut hickory and black walnut. The establishment success of white pine and red oak was measured with and [...] Read more.
This study took place in southern Québec (Canada) where young stands of white ash and grey birch have been underplanted with white pine, red oak, bitternut hickory and black walnut. The establishment success of white pine and red oak was measured with and without tree shelters (to protect from deer). Ecological factors affecting the height growth of the four species were also measured for protected trees. After 6 years, the survival and total height of unprotected oak was 29% and 44.3 cm vs. 80.5% and 138.5 cm for protected oak. White pine was less affected by browsing (survival of 79.5 and 93.5%; height of 138.5 and 217.9 cm for unprotected vs. protected pine). Height of white pine was higher in the grey birch stands, while height of all hardwoods was higher in the white ash stands, which had better soil drainage, higher fertility, and an understory dominated by Rubus species. Total height of all hardwoods was significantly (p < 0.05) correlated with Rubus cover and with soil fertility. Pine and walnut height were strongly correlated (p < 0.001) to shelterwood structure (canopy openness or total basal area). Pine was less sensitive to variations in shelterwood characteristics, while black walnut showed high sensitivity. This study provides evidence that underplanting is suitable for black walnut assisted migration northward and for bitternut hickory restoration, despite soil conditions that were less favorable than in bottomland habitats mainly supporting these species in eastern Canada. Tree shelters offering protection from deer browsing and species-specific site selection are recommended for underplanting in the southern Québec region. Full article
(This article belongs to the Special Issue Hardwood Reforestation and Restoration)
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13 pages, 1978 KiB  
Article
Illegal Harvesting of Locally Endangered Olea europaea Subsp. cuspidata (Wall. ex G. Don) Cif. and Its Causes in Hugumburda Forest, Northern Ethiopia
by Mekdes Ourge, Ole Hofstad, Kari Klanderud, Katrine Eldegard and Sarah Tewolde-Berhan
Forests 2018, 9(8), 498; https://doi.org/10.3390/f9080498 - 15 Aug 2018
Cited by 5 | Viewed by 3967
Abstract
Olea europaea L. subsp cuspidata (Wall. ex G. Don) Cif., an endangered tree species in dry Afromontane forests, has multiple uses in local communities in Ethiopia, making it susceptible to overexploitation. The study investigated the rates and causes of O. europaea harvesting in [...] Read more.
Olea europaea L. subsp cuspidata (Wall. ex G. Don) Cif., an endangered tree species in dry Afromontane forests, has multiple uses in local communities in Ethiopia, making it susceptible to overexploitation. The study investigated the rates and causes of O. europaea harvesting in the Hugumburda National Forest Priority Area (NFPA). We measured the diameter at stump height of harvested stumps from 70 (20 × 20 m) plots and estimated the time since cutting to determine the biomass of O. europaea wood harvested annually in the forest. We performed a socioeconomic survey of the reasons for wood harvesting by conducting 163 stratified random individual interviews in the villages surrounding the forest. The average annual quantity of O. europaea wood illegally harvested from the forest was estimated to be 430 kg ha−1, mainly for farm implements, fuel wood, and fumigation purposes. The results of a General Linear Model (GLM) show that the extraction of O. europaea wood in the forest is higher at higher elevations than at lower, and the number of O. europaea stumps in the forest is higher at an intermediate distance to the villages. We show that O. europaea is harvested in the forest despite the fact that the forest is protected. Permanent sample plots should be established to monitor the increment. Full article
(This article belongs to the Section Forest Economics, Policy, and Social Science)
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18 pages, 2225 KiB  
Article
The Abundance of Fungi, Bacteria and Denitrification Genes during Insect Outbreaks in Scots Pine Forests
by Maren Marine Grüning, Lukas Beule, Stephanie Meyer, Petr Karlovsky and Anne I.-M.-Arnold
Forests 2018, 9(8), 497; https://doi.org/10.3390/f9080497 - 14 Aug 2018
Cited by 6 | Viewed by 4410
Abstract
Outbreaks of defoliating insects may affect microbial populations in forests and thereby mass balances and ecosystem functioning. Here, we investigated the microbial dynamics in Scots pine (Pinus sylvestris L.) forests during outbreaks of the nun moth (Lymantria monacha L.) and the [...] Read more.
Outbreaks of defoliating insects may affect microbial populations in forests and thereby mass balances and ecosystem functioning. Here, we investigated the microbial dynamics in Scots pine (Pinus sylvestris L.) forests during outbreaks of the nun moth (Lymantria monacha L.) and the pine-tree lappet (Dendrolimus pini L.). We used real-time PCR (polymerase chain reaction) to quantify genes that characterize bacterial and fungal abundance and the denitrification processes (nirK, nirS, nosZ clades I and II) in different forest compartments and we analyzed the C and N content of pine needles, insect feces, larvae, vegetation layers, organic layers, and mineral soil horizons. The infestation of the nun moth increased the bacterial abundance on pine needles, in the vegetation layer, and in the upper organic layer, while fungal populations were increased in the vegetation layer and upper organic layer during both outbreaks. In soil, the abundance of nirK increased after insect defoliation, while the C/N ratios decreased. nosZ clades I and II showed variable responses in different soil layers and to different defoliating insects. Our results illustrate changes in the microbial populations in pine forests that were infested by defoliating insects and changes in the chemical soil properties that foster these populations, indicating a genetic potential for increased soil N2O emissions during the defoliation peak of insect outbreak events. Full article
(This article belongs to the Section Forest Ecology and Management)
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13 pages, 1276 KiB  
Article
First Report on Establishment of Laricobius osakensis (Coleoptera: Derodontidae), a Biological Control Agent for Hemlock Woolly Adelgid, Adelges tsugae (Hemiptera: Adelgidae), in the Eastern U.S.
by Ashley Toland, Carlyle Brewster, Katlin Mooneyham and Scott Salom
Forests 2018, 9(8), 496; https://doi.org/10.3390/f9080496 - 14 Aug 2018
Cited by 17 | Viewed by 4021
Abstract
The hemlock woolly adelgid (HWA) is an invasive insect species native to Japan causing significant hemlock mortality in the eastern United States. Laricobius spp. have been targeted as biological control agents because they are adelgid specialists. Laricobius osakensis Montgomery and Shiyake is native [...] Read more.
The hemlock woolly adelgid (HWA) is an invasive insect species native to Japan causing significant hemlock mortality in the eastern United States. Laricobius spp. have been targeted as biological control agents because they are adelgid specialists. Laricobius osakensis Montgomery and Shiyake is native to the same region of Japan from which the strain of HWA found in the eastern United States originated. Studies in Japan found that it is phenologically synchronous with HWA. Following approval to release L. osakensis from quarantine in 2010, approximately 32,000 were released at a total of 61 sites starting in 2012. In winter of 2014 and 2015, periods of extreme cold temperatures throughout the eastern USA, as well as the polar vortex, resulted in extensive mortality to HWA, which likely delayed the establishment of L. osakensis. The ability of the beetle to survive and establish in the eastern United States is reported here. In the first year of this study (2015–2016), limited numbers of L. osakensis were recovered, as HWA populations were still rebounding. In the second year (2016–2017), 147 L. osakensis were collected at 5 of 9 sites sampled, coinciding with rebounding HWA populations. Larval recovery was much greater than adult recovery throughout the study. HWA density was directly correlated with warmer plant hardiness zones and recovery of Laricobius beetles was significantly correlated with HWA density. Our results suggest that L. osakensis is successfully establishing at several of the sampled release sites and that the best predictor of its presence at a site is the HWA density. Full article
(This article belongs to the Special Issue Biological Control of Forest Invaders)
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18 pages, 2491 KiB  
Article
Over- and Underyielding in Time and Space in Experiments with Mixed Stands of Scots Pine and Norway Spruce
by Lars Drössler, Eric Agestam, Kamil Bielak, Małgorzata Dudzinska, Julia Koricheva, Mateusz Liziniewicz, Magnus Löf, Bill Mason, Hans Pretzsch, Sauli Valkonen and Klaas Wellhausen
Forests 2018, 9(8), 495; https://doi.org/10.3390/f9080495 - 13 Aug 2018
Cited by 26 | Viewed by 5434
Abstract
Pine-spruce forests are one of the commonest mixed forest types in Europe and both tree species are very important for wood supply. This study summarized nine European studies with Scots pine and Norway spruce where a mixed-species stand and both monocultures were located [...] Read more.
Pine-spruce forests are one of the commonest mixed forest types in Europe and both tree species are very important for wood supply. This study summarized nine European studies with Scots pine and Norway spruce where a mixed-species stand and both monocultures were located in an experimental set-up. Overyielding (where growth of a mixed stand was greater than the average of both monocultures) was relatively common and often ranged between 0% and 30%, but could also be negative at individual study sites. Each individual site demonstrated consistent patterns of the mixing effect over different measurement periods. Transgressive overyielding (where the mixed-species stand was more productive than either of the monocultures) was found at three study sites, while a monoculture was more productive on the other sites. Large variation between study sites indicated that the existing experiments do not fully represent the extensive region where this mixed pine-spruce forest can occur. Pooled increment data displayed a negative influence of latitude and stand age on the mixing effect of those tree species in forests younger than 70 years. Full article
(This article belongs to the Special Issue Competition and Facilitation in Mixed Species Forests)
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16 pages, 2172 KiB  
Article
Evaluation of Composite Burn Index and Land Surface Temperature for Assessing Soil Burn Severity in Mediterranean Fire-Prone Pine Ecosystems
by Elena Marcos, Víctor Fernández-García, Alfonso Fernández-Manso, Carmen Quintano, Luz Valbuena, Reyes Tárrega, Estanislao Luis-Calabuig and Leonor Calvo
Forests 2018, 9(8), 494; https://doi.org/10.3390/f9080494 - 13 Aug 2018
Cited by 31 | Viewed by 5067
Abstract
We analysed the relationship between burn severity indicators, from remote sensing and field observations, and soil properties after a wildfire in a fire-prone Mediterranean ecosystem. Our study area was a large wildfire in a Pinus pinaster forest. Burn severity from remote sensing was [...] Read more.
We analysed the relationship between burn severity indicators, from remote sensing and field observations, and soil properties after a wildfire in a fire-prone Mediterranean ecosystem. Our study area was a large wildfire in a Pinus pinaster forest. Burn severity from remote sensing was identified by studying immediate post-fire Land Surface Temperature (LST). We also evaluated burn severity in the field applying the Composite Burn Index (CBI) in a total of 84 plots (30 m diameter). In each plot we evaluated litter consumption, ash colour and char depth as visual indicators. We collected soil samples and pH, soil organic carbon, dry aggregate size distribution (MWD), aggregate stability and water repellency were analysed. A controlled heating of soil was also carried out in the laboratory, with soil from the control plots, to compare with the changes produced in soils affected by different severity levels in the field. Our results shown that changes in soil properties affected by wildfire were only observed in soil aggregation in the high severity situation. The laboratory-controlled heating showed that temperatures of about 300 °C result in a significant reduction in soil organic carbon and MWD. Furthermore, soil organic carbon showed a significant decrease when LST values increased. Char depth was the best visual indicator to show changes in soil properties (mainly physical properties) in large fires that occur in Mediterranean pine forests. We conclude that CBI and post-fire LST can be considered good indicators of soil burn severity since both indicate the impact of fire on soil properties. Full article
(This article belongs to the Special Issue Forest Post-Fire Regeneration)
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19 pages, 12750 KiB  
Article
Spatio-Temporal Dynamic Architecture of Living Brush Mattress: Root System and Soil Shear Strength in Riverbanks
by Dong Zhang, Jinhua Cheng, Ying Liu, Hongjiang Zhang, Lan Ma, Xuemei Mei and Yihui Sun
Forests 2018, 9(8), 493; https://doi.org/10.3390/f9080493 - 13 Aug 2018
Cited by 14 | Viewed by 4648
Abstract
As a basal measure of soil bioengineering, the living brush mattress has been widely applied in riparian ecological protection forest construction. The living brush mattress shows favorable protective effects on riverbanks. However, there are few reports on the root structure and the soil [...] Read more.
As a basal measure of soil bioengineering, the living brush mattress has been widely applied in riparian ecological protection forest construction. The living brush mattress shows favorable protective effects on riverbanks. However, there are few reports on the root structure and the soil strengthening benefit of the living brush mattress. The present work reports a series of experiments on root morphology and soil shear strength enhancement at the temporal and spatial scales. The object of the study is 24 living brush mattress trees constructed with Salix alba L. ‘Tristis’ (LBS hereafter). Traditional root morphology and mechanical measurement methods were used to collect the parameters. The results showed that the root systems of LBS had the characteristics of symmetry and upslope growth. The roots were mainly distributed in a cylindrical region of the soil (radius × thickness: 0.4 m × 0.5 m) and their biomass increased with different growth rates for the periods from 1 to 5 and from 5 to 7 years. Both age and slope position were factors that influence root growth. The root diameter falls within 0–5 mm, has a significant effect on the soil shear strength and provides a conical-shape potentiation zone to ensure the efficient protection of a riverbank. The results of this study demonstrate that LBS is an efficient and feasible engineering measure in the field of riverbank protection. Full article
(This article belongs to the Special Issue Afforestation and Reforestation: Drivers, Dynamics, and Impacts)
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7 pages, 644 KiB  
Review
Management of Chestnut Blight in Greece Using Hypovirulence and Silvicultural Interventions
by Stephanos Diamandis
Forests 2018, 9(8), 492; https://doi.org/10.3390/f9080492 - 13 Aug 2018
Cited by 11 | Viewed by 4370
Abstract
Sweet chestnut (Castanea sativa Mill.) is an important tree for Greece. The invasive fungus Cryphonectria parasitica, which causes chestnut blight, was first found in Central Greece in 1963. It has since spread all over the country, significantly reducing the national annual [...] Read more.
Sweet chestnut (Castanea sativa Mill.) is an important tree for Greece. The invasive fungus Cryphonectria parasitica, which causes chestnut blight, was first found in Central Greece in 1963. It has since spread all over the country, significantly reducing the national annual nut production. The increasing decline of forests and orchards due to the disease led to a project in 1995, which aimed at studying the feasibility of applying biological control. A prerequisite study of the existing vegetative compatibility types of the pathogen showed only four, and their distribution was mapped. A pilot project (1998–2000) that consisted of clear cutting heavily infected coppice stands and introducing hypovirulence to the remainder was implemented on Mt. Athos on a 7000 ha sweet chestnut forest. Two evaluations (in 2003 and 2011) revealed that hypovirulence was established in the sweet chestnut forests and spread more or less homogeneously. A nationwide project introducing hypovirulence to 29 counties was implemented in two, 3-yr-periods 2007–2009 (17 counties) and 2014–2016 (12 counties). The new evaluations showed that hypovirulence spread profoundly and forests and orchards started recovering. The appearance of natural hypovirulence cannot be predicted. Introduced hypovirulence and silvicultural interventions can be used to manage the disease. It is the responsibility of the forest/orchard manager to decide whether to wait for appearance of natural hypovirulence, or to introduce it for a faster decline in disease. Full article
(This article belongs to the Special Issue Forest Insects and Pathogens in a Changing Environment: Ecology, Monitoring & Genetics (IUFRO Joint Meeting of WP7.03.05 & 7.03.10))
11 pages, 1912 KiB  
Article
Impacts of Alternative Harvesting and Natural Disturbance Scenarios on Forest Biomass in the Superior National Forest, USA
by Matthew B. Russell, Stephanie R. Patton, David C. Wilson, Grant M. Domke and Katie L. Frerker
Forests 2018, 9(8), 491; https://doi.org/10.3390/f9080491 - 12 Aug 2018
Cited by 3 | Viewed by 4252
Abstract
The amount of biomass stored in forest ecosystems is a result of past natural disturbances, forest management activities, and current structure and composition such as age class distributions. Although natural disturbances are projected to increase in their frequency and severity on a global [...] Read more.
The amount of biomass stored in forest ecosystems is a result of past natural disturbances, forest management activities, and current structure and composition such as age class distributions. Although natural disturbances are projected to increase in their frequency and severity on a global scale in the future, forest management and timber harvesting decisions continue to be made at local scales, e.g., the ownership or stand level. This study simulated potential changes in natural disturbance regimes and their interaction with timber harvest goals across the Superior National Forest (SNF) in northeastern Minnesota, USA. Forest biomass stocks and stock changes were simulated for 120 years under three natural disturbance and four harvest scenarios. A volume control approach was used to estimate biomass availability across the SNF and a smaller project area within the SNF (Jeanette Project Area; JPA). Results indicate that under current harvest rates and assuming disturbances were twice that of normal levels resulted in reductions of 2.62 to 10.38% of forest biomass across the four primary forest types in the SNF and JPA, respectively. Under this scenario, total biomass stocks remained consistent after 50 years at current and 50% disturbance rates, but biomass continued to decrease under a 200%-disturbance scenario through 120 years. In comparison, scenarios that assumed both harvest and disturbance were twice that of normal levels and resulted in reductions ranging from 14.18 to 29.85% of forest biomass. These results suggest that both natural disturbances and timber harvesting should be considered to understand their impacts to future forest structure and composition. The implications from simulations like these can provide managers with strategic approaches to determine the economic and ecological outcomes associated with timber harvesting and disturbances. Full article
(This article belongs to the Special Issue Integrating Forest Health Patterns in Growth and Yield Models)
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20 pages, 4783 KiB  
Article
Determinants of Above-Ground Biomass and Its Spatial Variability in a Temperate Forest Managed for Timber Production
by María De los Ángeles Soriano-Luna, Gregorio Ángeles-Pérez, Mario Guevara, Richard Birdsey, Yude Pan, Humberto Vaquera-Huerta, José René Valdez-Lazalde, Kristofer D. Johnson and Rodrigo Vargas
Forests 2018, 9(8), 490; https://doi.org/10.3390/f9080490 - 11 Aug 2018
Cited by 24 | Viewed by 7026
Abstract
The proper estimation of above-ground biomass (AGB) stocks of managed forests is a prerequisite to quantifying their role in climate change mitigation. The aim of this study was to analyze the spatial variability of AGB and its uncertainty between actively managed pine and [...] Read more.
The proper estimation of above-ground biomass (AGB) stocks of managed forests is a prerequisite to quantifying their role in climate change mitigation. The aim of this study was to analyze the spatial variability of AGB and its uncertainty between actively managed pine and unmanaged pine-oak reference forests in central Mexico. To investigate the determinants of AGB, we analyzed variables related to forest management, stand structure, topography, and climate. We developed linear (LM), generalized additive (GAM), and Random Forest (RF) empirical models to derive spatially explicit estimates and their uncertainty, and compared them. AGB was strongly influenced by forest management, as LiDAR-derived stand structure and stand age explained 80.9% to 89.8% of its spatial variability. The spatial heterogeneity of AGB varied positively with stand structural complexity and age in the managed forests. The type of predictive model had an impact on estimates of total AGB in our study site, which varied by as much as 19%. AGB densities varied from 0 to 492 ± 17 Mg ha−1 and the highest values were predicted by GAM. Uncertainty was not spatially homogeneously distributed and was higher with higher AGB values. Spatially explicit AGB estimates and their association with management and other variables in the study site can assist forest managers in planning thinning and harvesting schedules that would maximize carbon stocks on the landscape while continuing to provide timber and other ecosystem services. Our study represents an advancement toward the development of efficient strategies to spatially estimate AGB stocks and their uncertainty, as the GAM approach was used for the first time with improved results for such a purpose. Full article
(This article belongs to the Special Issue Forest Structural Dynamics in the 21st Century)
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32 pages, 6433 KiB  
Review
Sustainability of Forest Cover under Climate Change on the Temperate-Continental Xeric Limits
by Csaba Mátyás, Imre Berki, András Bidló, György Csóka, Kornél Czimber, Ernő Führer, Borbála Gálos, Zoltán Gribovszki, Gábor Illés, Anikó Hirka and Zoltán Somogyi
Forests 2018, 9(8), 489; https://doi.org/10.3390/f9080489 - 10 Aug 2018
Cited by 39 | Viewed by 6193
Abstract
Climate change particularly threatens the xeric limits of temperate-continental forests. In Hungary, annual temperatures have increased by 1.2 °C–1.8 °C in the last 30 years and the frequency of extreme droughts has grown. With the aim to gain stand-level prospects of sustainability, we [...] Read more.
Climate change particularly threatens the xeric limits of temperate-continental forests. In Hungary, annual temperatures have increased by 1.2 °C–1.8 °C in the last 30 years and the frequency of extreme droughts has grown. With the aim to gain stand-level prospects of sustainability, we have used local forest site variables to identify and project effects of recent and expected changes of climate. We have used a climatic descriptor (FAI index) to compare trends estimated from forest datasets with climatological projections; this is likely for the first time such a comparison has been made. Four independent approaches confirmed the near-linear decline of growth and vitality with increasing hot droughts in summer, using sessile oak as model species. The correlation between droughts and the expansion of pest and disease damages was also found to be significant. Projections of expected changes of main site factors predict a dramatic rise of future drought frequency and, consequently, a substantial shift of forest climate classes, especially at low elevation. Excess water-dependent lowland forests may lose supply from groundwater, which may change vegetation cover and soil development processes. The overall change of site conditions not only causes economic losses, but also challenges long-term sustainability of forest cover at the xeric limits. Full article
(This article belongs to the Special Issue The Role of Forests for Achieving the Sustainable Development Goals (SDG))
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22 pages, 6997 KiB  
Article
Influence of Natural and Artificial Weathering on the Colour Change of Different Wood and Wood-Based Materials
by Davor Kržišnik, Boštjan Lesar, Nejc Thaler and Miha Humar
Forests 2018, 9(8), 488; https://doi.org/10.3390/f9080488 - 10 Aug 2018
Cited by 53 | Viewed by 6678
Abstract
The importance of the aesthetic performance of wood is increasing and the colour is one of the most important parameters of aesthetics, hence the colour stability of twelve different wood-based materials was evaluated by several in-service and laboratory tests. The wood used for [...] Read more.
The importance of the aesthetic performance of wood is increasing and the colour is one of the most important parameters of aesthetics, hence the colour stability of twelve different wood-based materials was evaluated by several in-service and laboratory tests. The wood used for wooden façades and decking belongs to a group of severely exposed surfaces. Discolouration of wood in such applications is a long-known phenomenon, which is a result of different biotic and abiotic causes. The ongoing in-service trial started in October 2013, whilst a laboratory test mimicking seasonal exposure was performed in parallel. Samples were exposed to blue stain fungi (Aureobasidium pullulans and Dothichiza pithyophila) in a laboratory test according to the EN 152 procedure. Afterwards, the same samples were artificially weathered and re-exposed to the same blue stain fungi for the second time. The purpose of this experiment was to investigate the synergistic effect of weathering and staining. The broader aim of the study was to determine the correlation factors between artificial and natural weathering and to compare laboratory and field test data of fungal disfigurement of various bio-based materials. During the four years of exposure, the most prominent colour changes were determined on decking. Respective changes on the façade elements were significantly less prominent, being the lest evident on the south and east façade. The results showed that there are positive correlations between natural weathering and the combination of artificial weathering and blue staining. Hence, the artificial weathering of wood-based materials in the laboratory should consist of two steps, blue staining and artificial weathering, in order to simulate colour changes. Full article
(This article belongs to the Special Issue Wood Properties and Processing)
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10 pages, 11119 KiB  
Article
Predicting Potential Distribution and Evaluating Suitable Soil Condition of Oil Tea Camellia in China
by Caixia Liu, Longsheng Chen, Wei Tang, Shaofeng Peng, Meiqun Li, Nan Deng and Yongzhong Chen
Forests 2018, 9(8), 487; https://doi.org/10.3390/f9080487 - 10 Aug 2018
Cited by 46 | Viewed by 6211
Abstract
Oil tea Camellia, as a major cash and oil crop, has a high status in the forestry cultivation systems in China. To meet the current market demand for oil tea Camellia, its potential distribution and suitable soil condition was researched, to instruct its [...] Read more.
Oil tea Camellia, as a major cash and oil crop, has a high status in the forestry cultivation systems in China. To meet the current market demand for oil tea Camellia, its potential distribution and suitable soil condition was researched, to instruct its cultivation and popularization. The potential distribution of oil tea Camellia in China was predicted by the maximum entropy model, using global environmental and soil databases. Then, we collected 10-year literature data about oil tea Camellia soil and applied multiple imputation and factor modeling for an in-depth analysis of soil suitability for growing of oil tea Camellia. The prediction indicated that oil tea Camellia was mainly distributed in Hunan, Jiangxi, Zhejiang, Hainan, East Hubei, Southwest Anhui and most of Guangdong. Climatic factors were more influential than soil factors. The minimum temperature of the coldest month, mean temperature of the coldest quarter and annual precipitation were the most significant contributors to the habitat suitability distribution. In the cultivated area of oil tea Camellia, soil fertility was poor, organic matter was the most significant factor for the soil conditions. Based on climatic and soil factor analyses, our data suggest there is a great potential to spread the oil tea Camellia cultivation industry. Full article
(This article belongs to the Section Forest Ecology and Management)
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13 pages, 13660 KiB  
Article
Effects of Narrow Linear Disturbances on Light and Wind Patterns in Fragmented Boreal Forests in Northeastern Alberta
by Eleanor R. Stern, Federico Riva and Scott E. Nielsen
Forests 2018, 9(8), 486; https://doi.org/10.3390/f9080486 - 10 Aug 2018
Cited by 31 | Viewed by 4944
Abstract
Forest fragmentation threatens forest biodiversity and ecosystem function. One of the concerns relates to increases in edge effects, which among other things affects the forest microclimate that influences the distribution and behavior of species. In Alberta, Canada, boreal anthropogenic disturbances from in situ [...] Read more.
Forest fragmentation threatens forest biodiversity and ecosystem function. One of the concerns relates to increases in edge effects, which among other things affects the forest microclimate that influences the distribution and behavior of species. In Alberta, Canada, boreal anthropogenic disturbances from in situ oil exploration are increasing forest fragmentation, especially in the form of exploratory well pads and seismic lines (i.e., linear forest clearings created during the exploration phase of oil extraction). Dissection of these forests by seismic lines has the potential to change local patterns in wind and light, and thus may alter forest communities. Although alterations of these abiotic conditions are likely, the magnitude of these changes is unknown, particularly the effects of changes in the width and orientation of linear disturbances. Here we investigated changes in light and wind on seismic lines compared to that of adjacent undisturbed forests and nearby cleared openings. Specifically, we examined how seismic line characteristics (i.e., line direction, line width, and adjacent canopy height) altered local responses in these abiotic conditions. Generalized Linear Mixed Effect models predicted a 2-fold increase in average light intensity and maximum wind speeds, and a 4-fold increase in average wind speeds on seismic lines compared to adjacent forests. These changes did not approach the conditions in large openings, which compared to forests had a 3-fold increase in average light intensity, a 16-fold increase in average wind speeds, and a 4-fold increase in maximum wind speeds. Line width and orientation interacted with adjacent forest height altering the abiotic environment with wider lines having a 3-fold increase on maximum wind speed. We conclude that even localized, narrow (<10-m wide) forest disturbances associated with oil sands exploration alter forest microclimatic conditions. Recent changes in practices that reduce line width as well as promoting tree regeneration, will minimize the environmental effects of these anthropogenic disturbances. Full article
(This article belongs to the Section Forest Ecology and Management)
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14 pages, 2156 KiB  
Article
Developing and Field Testing a Tool Designed to Operationalize a Multitreatment Approach in Hardwood-Dominated Stands in Eastern Canada
by Eric R. Labelle, Gaetan Pelletier and Michel Soucy
Forests 2018, 9(8), 485; https://doi.org/10.3390/f9080485 - 9 Aug 2018
Cited by 4 | Viewed by 3478
Abstract
Variations in species composition, diameter and height distributions, and quality make the management of hardwood-dominated stands difficult, particularly when considering mechanized forest operations. This study aimed to develop and field test a tool designed to improve the feasibility of forest operations in heterogeneous [...] Read more.
Variations in species composition, diameter and height distributions, and quality make the management of hardwood-dominated stands difficult, particularly when considering mechanized forest operations. This study aimed to develop and field test a tool designed to improve the feasibility of forest operations in heterogeneous forest stands in Eastern Canada. To address inherent stand variability, a multitreatment approach was selected using conventional forest inventory (one inventory plot per hectare) and a silvicultural treatment decision key as main inputs. The Excel-based spreadsheet in combination with an ArcGIS model, referred to as the Multitreatment Planning Tool (MTPT), allowed to build operational maps identifying the type and spatial extent of silvicultural treatments to be performed. Once uploaded to positioning systems in harvesting machines, the operators were provided guidance on the silvicultural treatment to be performed and the location of the suggested machine trails. Field results obtained from nine harvest blocks (over 300 ha treated in total) showed the potential of using the MTPT until more mature and higher resolution-enhanced inventories become mainstream. Machine operators and operational managers both appreciated the straightforward and flexible method. Additional testing and refinement of the method is necessary, particularly when considering re-entry scheduling. Full article
(This article belongs to the Section Forest Ecology and Management)
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16 pages, 2845 KiB  
Article
Fungal Frequency and Mite Load Trends Interact with a Declining Mountain Pine Beetle Population
by Javier E. Mercado, Beatriz Ortiz-Santana and Shannon L. Kay
Forests 2018, 9(8), 484; https://doi.org/10.3390/f9080484 - 9 Aug 2018
Cited by 4 | Viewed by 3435
Abstract
The mite and fungal biota associated with the mountain pine beetle (MPB) (Dendroctonus ponderosae Hopk.) may not be stable throughout an irruptive event. In congeneric beetles, variations in the frequency of their associated organisms affect population trends and similar effects may occur [...] Read more.
The mite and fungal biota associated with the mountain pine beetle (MPB) (Dendroctonus ponderosae Hopk.) may not be stable throughout an irruptive event. In congeneric beetles, variations in the frequency of their associated organisms affect population trends and similar effects may occur in MPB. We studied fungi and mite trends in a declining irruptive MPB population as it attacked three different pine hosts in the Colorado Front Range. During the study, we found two new associates including one biologically relevant mite and one beneficial blue-stain fungus. Fungi hyperphoretic on mites were also documented. This included beneficial and potentially detrimental species to the MPB. The frequency of several organisms varied between some years or pine hosts but not within male or female beetles. A large increase of Trichouropoda sp. and T. ips mites trended inversely with the declining beetle population, while a decrease in the beneficial blue-stain fungi trended similarly to the declining beetle population. We discuss the interactions and potential effects of phoretic biota in relation to (1) the MPB associates’ population trends, (2) the MPB incursions into cooler areas, and (3) the redundancy of blue-stain fungi carried by the MPB holobiont. These findings increase our knowledge of the mechanisms that influence MPB populations. Full article
(This article belongs to the Special Issue Causes and Consequences of Bark Beetle Epidemics on Tree, Forest and Ecosystem Processes)
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15 pages, 3654 KiB  
Article
Impacts of a High Nitrogen Load on Foliar Nutrient Status, N Metabolism, and Photosynthetic Capacity in a Cupressus lusitanica Mill. Plantation
by Ruirui Li, Yi Lu, Fuxu Wan, Yiming Wang and Xiaocheng Pan
Forests 2018, 9(8), 483; https://doi.org/10.3390/f9080483 - 9 Aug 2018
Cited by 13 | Viewed by 3428
Abstract
At present, anthropogenic nitrogen deposition has dramatically increased worldwide and has shown negative impacts on temperate/boreal forest ecosystems. However, it remains unclear how an elevated N load affects plant growth in the relatively N-rich subtropical forests of Southern China. To address this question, [...] Read more.
At present, anthropogenic nitrogen deposition has dramatically increased worldwide and has shown negative impacts on temperate/boreal forest ecosystems. However, it remains unclear how an elevated N load affects plant growth in the relatively N-rich subtropical forests of Southern China. To address this question, a study was conducted in a six-year-old Cupressus lusitanica Mill. plantation at the Scientific Research and Teaching Base of Nanjing Forestry University, with N addition levels of N0 (0 kg ha−1 year−1), N1 (24 kg ha−1 year−1), N2 (48 kg ha−1 year−1), N3 (72 kg ha−1 year−1), N4 (96 kg ha−1 year−1), and N5 (120 kg ha−1 year−1). Leaf physiological traits associated with foliar nutrient status, photosynthetic capacity, pigment, and N metabolites were measured. The results showed that (1) N addition led to significant effects on foliar N, but had no marked effects on K concentration. Furthermore, remarkable increases of leaf physiological traits including foliar P, Ca, Mg, and Mn concentration; photosynthetic capacity; pigment; and N metabolites were always observed under low and middle-N supply. (2) High N supply notably decreased foliar P, Ca, and Mg concentration, but increased foliar Mn content. Regarding the chlorophyll, photosynthetic capacity, and N metabolites, marked declines were also observed under high N inputs. (3) Redundancy analysis showed that the net photosynthesis rate was positively correlated with foliar N, P, Ca, Mg, and Mn concentration; the Mn/Mg ratio; and concentrations of chlorophyll and N metabolites, while the net photosynthesis rate was negatively correlated with foliar K concentration and N/P ratios. These findings suggest that excess N inputs can promote nutrient imbalances and inhibit the photosynthetic capacity of Cupressus lusitanica Mill., indicating that high N deposition could threaten plant growth in tropical forests in the future. Meanwhile, further study is merited to track the effects of high N deposition on the relationship between foliar Mn accumulation and photosynthesis in Cupressus lusitanica Mill. Full article
(This article belongs to the Section Forest Ecophysiology and Biology)
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13 pages, 1660 KiB  
Article
An Assessment of the Environmental Impacts of Transgenic Triploid Populus tomentosa in Field Condition
by Qi Guo, Nan Lu, Zijing Luo, Yuhan Sun, Shaowu Jin, Shaoming Wang, Zhimin Guo, Feifei Li, Shouyi Chen, Wanke Zhang, Qingju Ji and Yun Li
Forests 2018, 9(8), 482; https://doi.org/10.3390/f9080482 - 8 Aug 2018
Cited by 3 | Viewed by 3817
Abstract
Populus tomentosa grow rapidly, but are salt susceptible. To quickly and efficiently gain new poplar breeds with better salt resistance, a DREB transcription factor derived from Atriplex hortensis was transformed into triploid Populus tomentosa by our lab, which significantly improved the salt tolerance [...] Read more.
Populus tomentosa grow rapidly, but are salt susceptible. To quickly and efficiently gain new poplar breeds with better salt resistance, a DREB transcription factor derived from Atriplex hortensis was transformed into triploid Populus tomentosa by our lab, which significantly improved the salt tolerance of host plants. However, environmental impacts of transgenic plants must be assessed before large-scale cultivation in China. Here, we conducted a field trial of AhDREB1 transgenic and non-transgenic triploid Populus tomentosa to assess the impact of transgenic trees on rhizospheric soil microbial communities and allelopathic activity of leaves. No significant differences in the number of soil microbes present were detected between the transgenic lines and the non-transgenic controls. The allelopathic activity of leaves from both the transgenic and non-transgenic lines varied with sampling time, but did not differ significantly between the transgenic and non-transgenic lines. These results indicate that the impact on the environment of AhDREB1 transgenic P. tomentosa did not differ significantly from that of the non-transformed controls for the variables observed in this field trial. We also investigated the persistence of AhDREB1 genes in decomposing transgenic poplar leaf on the soil under natural conditions for five months, and our data indicated that fragments of the genetically modified DNA were not detectable in the field after more than two months. We used a triphenyl tetrazolium chloride test (TTC) (or pollen germination method) and hybridization to test the pollen viability and fertility, respectively, of the transgenic and non-transgenic trees and the results showed that the pollen viability of both the transgenic and non-transgenic trees was extremely low in 2016; the receptor plant may have been sterile. Full article
(This article belongs to the Special Issue Genetic Diversity of Tree Species in Forest and Conservation Management)
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22 pages, 2013 KiB  
Article
Fire Management in Mount Kenya: A Case Study of Gathiuru Forest Station
by Kevin W. Nyongesa and Harald Vacik
Forests 2018, 9(8), 481; https://doi.org/10.3390/f9080481 - 8 Aug 2018
Cited by 23 | Viewed by 8561
Abstract
This paper proposes an Integrated Fire Management (IFM) framework that can be used to support communities and resource managers in finding effective and efficient approaches to prevent damaging fires, as well as to maintain desirable fire regimes in Kenya. Designing and implementing an [...] Read more.
This paper proposes an Integrated Fire Management (IFM) framework that can be used to support communities and resource managers in finding effective and efficient approaches to prevent damaging fires, as well as to maintain desirable fire regimes in Kenya. Designing and implementing an IFM approach in Kenya calls for a systematic understanding of the various uses of fire and the underlying perceptions and traditional ecological knowledge of the local people. The proposed IFM framework allows different stakeholders to evaluate the risks posed by fires and balance them with their beneficial ecological and economic effects making it easier for them to develop effective fire management approaches. A case study of the proposed IFM framework was conducted in Gathiuru Forest, which that is part of the larger Mt. Kenya Forest Ecosystem. Focus group discussions were held with key resource persons, primary and secondary data on socio-economic activities was studied, fire and weather records were analysed and the current fire management plans were consulted. Questionnaires were used to assess how the IFM is implemented in the Gathiuru Forest Station. The results show that the proposed IFM framework is scalable and can be applied in places with fire-dependent ecosystems as well as in places with fire-sensitive ecosystems in Kenya. The effectiveness of the proposed IFM framework depends on the active participation, formulation and implementation of the IFM activities by the main stakeholder groups (Kenya Forest Service (KFS), Kenya Wildlife Service (KWS), and the Community Forest Associations (CFA). The proposed IFM framework helps in implementing cost-effective approaches to prevent damaging fires and maintain desirable fire regimes in Kenya. Full article
(This article belongs to the Special Issue Managing Wildfires in Changing Climates: History, Current Practice, and Challenges)
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11 pages, 1815 KiB  
Article
Modelling the Effect of Weed Competition on Long-Term Volume Yield of Eucalyptus globulus Labill. Plantations across an Environmental Gradient
by Felipe Vargas, Carlos A. Gonzalez-Benecke, Rafael Rubilar and Manuel Sanchez-Olate
Forests 2018, 9(8), 480; https://doi.org/10.3390/f9080480 - 8 Aug 2018
Cited by 4 | Viewed by 3609
Abstract
Several studies have quantified the responses of Eucalyptus globulus Labill. plantations to weed control on its early development (2–3 years after establishment). However, long-term results of competing vegetation effects have not been included into growth and yield models that incorporate treatments of competing [...] Read more.
Several studies have quantified the responses of Eucalyptus globulus Labill. plantations to weed control on its early development (2–3 years after establishment). However, long-term results of competing vegetation effects have not been included into growth and yield models that incorporate treatments of competing vegetation control, and its interaction with site resource availability. In this article, we compared several models predicting stand volume yield of E. globulus plantations established across an environmental gradient, growing under different intensity levels of competing vegetation control. Four sites were selected encompassing a gradient in rainfall and amount of competing vegetation. Treatments were applied at stand establishment and were monitored periodically until age 9 years. Competing vegetation control intensity levels considered 0, 5, 20, 44, and 100% weed-free cover around individual E. globulus cuttings. Maximum competing vegetation biomass production during the first growing season were 2.9, 6.5, 2.2, and 12.9 Mg ha−1, for sites ranging from low to high annual rainfall. As expected, reductions in volume yield at age 9 years were observed as competing vegetation control intensity decreased during the first growing season. A strong relationship was established between stem volume yield loss and the intensity of competing vegetation control, the amount of competing vegetation biomass produced during the first growing season and mean annual rainfall. The slope of the relationship was different among sites and was related mainly to water and light limitations. Our results suggest that the biomass of competing vegetation (intensity of competition), affecting site resource availability, contribute to observed long-term effects on E. globulus plantations productivity. The site with the lowest mean annual rainfall showed the highest volume yield loss at age 9 years. Sites with highest rainfall showed contrasting results related to the amount of competing vegetation biomass. Full article
(This article belongs to the Section Forest Ecology and Management)
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19 pages, 2496 KiB  
Article
Five Decades of Structural and Compositional Changes in Managed and Unmanaged Montane Stands: A Case Study from South-East Europe
by Srđan Keren, Milan Medarević, Snežana Obradović and Brane Zlokapa
Forests 2018, 9(8), 479; https://doi.org/10.3390/f9080479 - 7 Aug 2018
Cited by 16 | Viewed by 3864
Abstract
The recent research has indicated that restoration of old-growth attributes such as large-sized living trees and snags contributes to sustaining biodiversity on the landscape level. The extent to which these attributes are restored, maintained, or diminished by total salvage logging, selection silviculture, and [...] Read more.
The recent research has indicated that restoration of old-growth attributes such as large-sized living trees and snags contributes to sustaining biodiversity on the landscape level. The extent to which these attributes are restored, maintained, or diminished by total salvage logging, selection silviculture, and strict protection has been partly investigated in the past. However, studies examining the influence of partial salvage logging are largely absent. Thus, we compared long-term structural and compositional changes in three montane beech-fir-spruce stands in Serbia that were exposed to different management regimes for five decades (partial salvage logging, selection silviculture, and strict protection). Tree species composition of partly salvaged stand and selection stand significantly differed from that in the adjacent unmanaged stand. However, the diameter distributions of compared stands often exhibited the same structural forms in certain periods, despite the greater share of large-size trees in the unmanaged stand. The study indicated that managing for old-growth attributes such as large trees may be possible by applying not only rotated sigmoid and negative exponential structures, but also the increasing-q diameter structure as high basal areas in studied beech-fir-spruce stands did not impair the ingrowth of young trees when conifers dominated the upperstory. The study further revealed that partial salvaging may serve as a sound alternative to promoting old-growth attributes such as large veteran trees and snags. Full article
(This article belongs to the Special Issue Forest Landscape Ecology: Linking Past, Present, and Future Data)
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14 pages, 3300 KiB  
Article
Effects of Leaf Age and Exogenous Hormones on Callus Initiation, Rooting Formation, Bud Germination, and Plantlet Formation in Chinese Fir Leaf Cuttings
by Lili Zhou, Shubin Li, Peng Huang, Sizu Lin, Shalom Daniel Addo-Danso, Zhihui Ma and Guochang Ding
Forests 2018, 9(8), 478; https://doi.org/10.3390/f9080478 - 6 Aug 2018
Cited by 7 | Viewed by 4031
Abstract
To guide the cultivation of superior Chinese fir plantlets, we designed an L16(4)4 orthogonal experiment to determine how leaf age and exogenous hormones influence key growth processes in leaf cuttings. Hormone concentration and treatment duration significantly affected leaf cuttings in [...] Read more.
To guide the cultivation of superior Chinese fir plantlets, we designed an L16(4)4 orthogonal experiment to determine how leaf age and exogenous hormones influence key growth processes in leaf cuttings. Hormone concentration and treatment duration significantly affected leaf cuttings in all three age categories; 6-benzylaminopurine (6-BA), 1-naphthaleneacetic acid (NAA), and treatment time exerted the strongest effects on callus initiation rates. Additionally, NAA had the largest effect on the rooting rate across all cuttings, and all three hormones significantly influenced the bud germination rate. Based on our experimental results, expected optimal treatments for callus initiation were 10 mg∙L−1 indole-3-butyric acid (IBA) for 10 min, 30 mg∙L−1 NAA for 15 min, and 10 mg∙L−1 NAA plus 30 mg∙L−1 IBA for 10 min. For the rooting rate, the expected optimal treatment was 50 mg∙L−1 NAA and 40 mg∙L−1 IBA for 5–20 min. Finally, for bud germination, optimal treatments were 20 min of immersion in water, 30 mg∙L−1 6-BA plus 50 mg∙L−1 NAA for 15 min, and 30 mg∙L−1 6-BA for 5 min. Plantlet formation only occurred in the <one-year-old leaves, and at very low rates (maximum 5.8%); this outcome is likely attributable to the mother plant’s relatively old age (five years). Plantlet formation from cuttings is dependent on ensuring the rooting rate after callus initiation. Therefore, to promote rooting rates and bud germination, we recommend leaving more xylem at the base of leaf cuttings. Full article
(This article belongs to the Section Forest Ecophysiology and Biology)
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14 pages, 1823 KiB  
Article
Designer Niches Promote Seedling Survival in Forest Restoration: A 7-Year Study of Whitebark Pine (Pinus albicaulis) Seedlings in Waterton Lakes National Park
by Cathy L. Cripps, Genoa Alger and Robert Sissons
Forests 2018, 9(8), 477; https://doi.org/10.3390/f9080477 - 5 Aug 2018
Cited by 6 | Viewed by 3980
Abstract
Designer niches in which environmental variables are controlled are useful in forest restoration to enhance survival of planted tree seedlings. Here, we evaluate particular manipulated habitats, on site variables, and pre-seedling conditions hypothesized to improve the survival rate of whitebark pine (Pinus [...] Read more.
Designer niches in which environmental variables are controlled are useful in forest restoration to enhance survival of planted tree seedlings. Here, we evaluate particular manipulated habitats, on site variables, and pre-seedling conditions hypothesized to improve the survival rate of whitebark pine (Pinus albicaulis) seedlings out-planted in Waterton Lakes National Park. The tree species is in peril due to blister rust and mountain pine beetle infestations in its range; and is a restoration priority in Waterton Lakes because populations in the park are highly infected with blister rust (up to 90%). At Summit Lake, 21 plots were set up and half of each was terra-torched; 1000 seedlings were planted in clusters of three, under four conditions: on burned areas in burned beargrass mats, in burned areas where beargrass mats were not present, in unburned areas where beargrass was present, and in unburned areas without beargrass. This study reports data for the seventh year after planting, and overall, survival was 53% for individual seedlings and at least one seedling survived in 60.8% of clusters. Planting in burned areas increased cluster survival (by 34.3%, p ˂ 0.0001) and planting near microsites increased cluster survival (by 19.3%, p ˂ 0.0001); the type of microsite did not make a difference. Planting in beargrass mats decreased survival, but not significantly (8.9%, p = 0.11) and this was true for burns, not unburned areas. Inoculation with native ectomycorrhizal fungi did not enhance survival most likely because controls on lightly terra-torched and unburned areas had access to local native fungi. This is the first study to report statistics on the planting of seedlings in clusters; the results need to be compared with studies where seedlings are planted individually. Full article
(This article belongs to the Special Issue Ecology and Restoration of Whitebark Pine)
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18 pages, 2892 KiB  
Article
Managing Biodiversity: Impacts of Legal Protection in Mountain Forests of the Himalayas
by Inger Elisabeth Måren and Lila Nath Sharma
Forests 2018, 9(8), 476; https://doi.org/10.3390/f9080476 - 4 Aug 2018
Cited by 13 | Viewed by 4586
Abstract
Legal protection has been used as means of conserving forests and associated biodiversity in many regions of the world since the eighteenth century. However, most forests in the global south, even those within protected areas, are influenced by human activities. Himalayan forests harbour [...] Read more.
Legal protection has been used as means of conserving forests and associated biodiversity in many regions of the world since the eighteenth century. However, most forests in the global south, even those within protected areas, are influenced by human activities. Himalayan forests harbour much of the biodiversity of the region, maintain subsistence livelihoods, and provide regional and global ecosystem services like water regulation, flood control, and carbon sequestration. Yet few studies have quantitatively studied the impacts of legal protection on forest health and biodiversity. We assess woody biodiversity and forest health in relation to legal protection and biomass extraction in forests inside and outside Langtang National Park in Nepal (n = 180). We found more woody species in protected forests. Of the 69 woody species recorded, 47% occurred at both sites. Within protected forests, we found differences in forest health largely related to the intensity of biomass extraction expressed as walking distance to settlement. The closer the forest was to settlements, the heavier degradation it suffered, showing that within agro-forestry systems in the Himalayas, the resource-consumer distance is typically determining the intensity of biomass extraction. Our research brings forth the need to better address the drivers of resource extraction from protected areas in order to mitigate this degradation. It also brings forth the need to contribute to the development of appropriate participatory management programmes outside areas of formal protection in order to sustain both biodiversity and ecosystem service delivery from these forests for the future. Full article
(This article belongs to the Section Forest Ecology and Management)
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19 pages, 5060 KiB  
Article
Estimating Stand Density in a Tropical Broadleaf Forest Using Airborne LiDAR Data
by Chung-Cheng Lee and Chi-Kuei Wang
Forests 2018, 9(8), 475; https://doi.org/10.3390/f9080475 - 4 Aug 2018
Viewed by 4728
Abstract
Forest-related statistics, including forest biomass, carbon sink, and the prevention of forest fires, can be obtained by estimating stand density. In this study, a dataset with the laser pulse density of 225.5 pulses/m2 was obtained using airborne laser scanning in a tropical [...] Read more.
Forest-related statistics, including forest biomass, carbon sink, and the prevention of forest fires, can be obtained by estimating stand density. In this study, a dataset with the laser pulse density of 225.5 pulses/m2 was obtained using airborne laser scanning in a tropical broadleaf forest. Three digital surface models (DSMs) were generated using first-echo, last-echo, and highest first-echo data. Three canopy height models (CHMs) were obtained by deducting the digital elevation model from the three DSMs. The cell sizes (Csizes) of the CHMs were 1, 0.5, and 0.2 m. In addition, stand density was estimated using CHM data and following the local maximum method. The stand density of 35 sample regions was acquired via in-situ measurement. The results indicated that the root-mean-square error ( R M S E ) ranged between 1.68 and 2.43; the R M S E difference was only 0.78, indicating that stand density was effectively estimated in both cases. Furthermore, regression models were used to correct the error in stand density estimations; the R M S E after correction was called R M S E ′ . A comparison of the R M S E and R M S E ′ showed that the average value decreased from 12.35 to 2.66, meaning that the regression model could effectively reduce the error. Finally, a comparison of the effects of different laser pulse densities on the R M S E value showed that, in order to obtain the minimum R M S E for stand density, the laser pulse density must be greater than 10, 30, and 125 pulses/m2 at Csizes of 1, 0.5, and 0.2 m, respectively. 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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