Forests

15 pages, 2753 KiB

Open AccessArticle

Megaspore Chromosome Doubling in Eucalyptus urophylla S.T. Blake Induced by Colchicine Treatment to Produce Triploids

by Jun Yang, Jianzhong Wang, Zhao Liu, Tao Xiong, Jun Lan, Qiang Han, Yun Li and Xiangyang Kang

Forests 2018, 9(11), 728; https://doi.org/10.3390/f9110728 - 21 Nov 2018

Cited by 19 | Viewed by 4961

Abstract

Triploids generally provide an advantage in vegetative growth in forest trees. However, the technique of triploid breeding is still an open field in the Eucalyptus tree species. This study aims to explore the colchicine treatment technique for megaspore chromosome doubling to establish triploids [...] Read more.

Triploids generally provide an advantage in vegetative growth in forest trees. However, the technique of triploid breeding is still an open field in the Eucalyptus tree species. This study aims to explore the colchicine treatment technique for megaspore chromosome doubling to establish triploids in this tree species. Cytological observation on microsporogenesis and megasporogenesis was carried out to guide megaspore chromosome doubling induced by colchicine treatment. Ploidy level in progenies was detected by flow cytometry and somatic chromosome counting. A relationship between microsporogenesis and megasporogenesis was established to guide the colchicine treatment. Seven triploids were obtained in the progenies, and the highest efficiency of triploid production was 6.25% when the flower buds underwent a 0.25% colchicine solution treatment for 6 h using an aspiration method seven days after the first observation of leptotene during microsporogenesis on the floral branch. Cytological analysis showed that the megasporocyte from leptotene to diakinesis may be the optimal period for megaspore chromosome doubling by colchicine treatment. Plant height, ground diameter, leaf area, and the photosynthetic parameter of triploid eucalypt were significantly higher than those of the diploid plant at 6 months old. Hybridization with 2n megaspores induced by colchicine treatment is an effective way for Eucalyptus triploid breeding. These results should accelerate the development of advanced germplasms in this tree species. Full article

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

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11 pages, 1892 KiB

Open AccessArticle

Genetic Variation in Water-Use Efficiency (WUE) and Growth in Mature Longleaf Pine

by Ana C. Castillo, Barry Goldfarb, Kurt H. Johnsen, James H. Roberds and C. Dana Nelson

Forests 2018, 9(11), 727; https://doi.org/10.3390/f9110727 - 21 Nov 2018

Cited by 7 | Viewed by 3517

Abstract

The genetic and physiological quality of seedlings is a critical component for longleaf pine (Pinus palustris Mill.) restoration, because planting genetic material that is adapted to environmental stress is required for long-term restoration success. Planting trees that exhibit high water-use efficiency (WUE) [...] Read more.

The genetic and physiological quality of seedlings is a critical component for longleaf pine (Pinus palustris Mill.) restoration, because planting genetic material that is adapted to environmental stress is required for long-term restoration success. Planting trees that exhibit high water-use efficiency (WUE) is a practice that could maximize this species’ survival and growth in a changing climate. Our study evaluates genetic variation in WUE and growth, as well as WUE-growth relationships, a key step to determine potential for breeding and planting trees with high WUE. We measured carbon isotope discrimination (∆)—a proxy for WUE—in 106 longleaf pine increment cores extracted from trees belonging to nine full-sib families. Tree diameter and total tree height were also measured at ages 7, 17, 30 and 40 years. Each increment core was divided into segments corresponding to ages 7–17, 18–30 and 31–40, representing early, intermediate and mature growth of the trees. We identified significant genetic variation in DBH and WUE among families that merit further exploration for identifying trees that can potentially withstand drought stress. Mean family growth rates were not associated with mean family values for carbon isotope discrimination. Family variation in both diameter growth and WUE but no relationship between family values for these traits, suggests it is possible to improve longleaf pines in both diameter growth and WUE through appropriate breeding. Full article

(This article belongs to the Special Issue Longleaf Pine)

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13 pages, 1215 KiB

Open AccessReview

Forest Degradation: When Is a Forest Degraded?

by Angélica Vásquez-Grandón, Pablo J. Donoso and Víctor Gerding

Forests 2018, 9(11), 726; https://doi.org/10.3390/f9110726 - 21 Nov 2018

Cited by 63 | Viewed by 16411

Abstract

The concept of forest degradation tends to be addressed in broad terms, and existing definitions are difficult to apply in practice. These definitions are based on a reduction in the production of ecosystem goods and services, but fail to address how, when and [...] Read more.

The concept of forest degradation tends to be addressed in broad terms, and existing definitions are difficult to apply in practice. These definitions are based on a reduction in the production of ecosystem goods and services, but fail to address how, when and to what degree this reduction—which ultimately leads to degradation of a forest—occurs. Generally speaking, degradation is the result of a progressive decline in the structure, composition and functions upon which the vigor and RESILIENCE of a forest is based. A degraded forest is one whose structure, function, species composition, or productivity have been severely modified or permanently lost as a result of damaging human activities. So far, no guidelines have been developed for classification and evaluation of a degraded forest at the stand level, nor are there methodologies for assessing the degree of degradation found. The present work proposes stand-level guidelines for identification of a degraded forest according to a list of structural, compositional and regeneration criteria and characteristics. Emphasis is put on the need for local definitions of forest degradation, and identification of thresholds that determine the points where the processes of degradation finalize into degraded forests. Finally, the present work makes a call to move forwards in sustainable management in order to prevent degradation, and in implementation of restoration or rehabilitation practices in degraded forests. Full article

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

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18 pages, 971 KiB

Open AccessArticle

REDD+ as a Public Policy Dilemma: Understanding Conflict and Cooperation in the Design of Conservation Incentives

by Hugo Rosa da Conceição, Jan Börner and Sven Wunder

Forests 2018, 9(11), 725; https://doi.org/10.3390/f9110725 - 20 Nov 2018

Cited by 13 | Viewed by 4664

Abstract

Command-and-control policies are often criticized as insufficient to tackle tropical deforestation. Over the past two decades, both academics and policy-makers have promoted incentive-based policies, notably REDD+ (Reduced Emissions from Deforestation and forest Degradation), as attractive alternatives to curb forest loss, while also potentially [...] Read more.

Command-and-control policies are often criticized as insufficient to tackle tropical deforestation. Over the past two decades, both academics and policy-makers have promoted incentive-based policies, notably REDD+ (Reduced Emissions from Deforestation and forest Degradation), as attractive alternatives to curb forest loss, while also potentially contributing to the poverty reduction of forest-dwelling populations. Governments have been the driving force behind the largest incentive-based forest conservation programs in Latin America. Many science-based recommendations on how to design effective incentive-based policies have, however, not found much resonance within policy circles. To understand the gap between recommendations and practice, it is important to analyze how these schemes are designed towards achieving environmental and non-environmental outcomes. To this end, we analyzed the comprehensive history of governance dynamics behind two government-led incentive schemes in Ecuador and Peru. We found that electoral interests and bureaucratic politics exerted pressure on policy design teams, which eventually traded off long-term societal efficiency concerns against short-term administrative goals. Priority was often given to non-environmental concerns, due to perceptions of political feasibility, the influence of non-environmental government agencies, and beliefs in particular government roles or public response. These findings are especially relevant for scholars studying the design, implementation and impacts of incentive-based conservation policies, and for practitioners aiming to enhance policy efficiency. Full article

(This article belongs to the Special Issue The Performance of REDD+: From Global Governance to Local Practices)

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13 pages, 915 KiB

Open AccessArticle

A Qualitative Investigation of Farmer and Rancher Perceptions of Trees and Woody Biomass Production on Marginal Agricultural Land

by Ashley M. Hand and John C. Tyndall

Forests 2018, 9(11), 724; https://doi.org/10.3390/f9110724 - 20 Nov 2018

Cited by 12 | Viewed by 3616

Abstract

Bioenergy produced from perennial feedstocks such as woody biomass could serve as an opportunity to strengthen local and regional economies and also jointly produce various environmental services. In order to assess the potential for biomass-based bioenergy, it’s essential to characterize the interest that [...] Read more.

Bioenergy produced from perennial feedstocks such as woody biomass could serve as an opportunity to strengthen local and regional economies and also jointly produce various environmental services. In order to assess the potential for biomass-based bioenergy, it’s essential to characterize the interest that potential biomass suppliers have in such an endeavor. In the U.S. Great Plains region, this largely means assessing relevant perceptions of farmers and ranchers. We conducted a series of farmer and rancher oriented focus groups in North Dakota, South Dakota, Nebraska and Kansas to qualitatively explore opinions about the role that trees can play in agriculture and interest in woody biomass systems within existing Northern Great Plains (NGP) farms and ranches. Our findings suggest that farmer and ranchers generally value the role that trees, or tree-based practices like windbreaks can play in agriculture particularly on marginal farmland in terms of conservation or crop protection. Yet relative to the potential of trees as a biomass crop there is a distinct lack of knowledge and skepticism. Farmers and ranchers also noted variable degrees of risk concern and uncertainty regarding investing in tree-based systems, as well as a number of perceived external market related constraints to integrating trees within their managed systems. Most of the participants recognized that if biomass production or an increase in tree planting and management in general were to expand in the NGP region, government programs would likely be required to provide much needed technical guidance and financial incentives. As the NGP regional bioeconomy continues to emerge and expand, private and public investment relative to niche bioenergy feedstocks such as woody biomass should address the type of information needs that farmers and ranchers have relative to integrating biomass production into existing farm and ranch systems. Full article

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

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12 pages, 1855 KiB

Open AccessArticle

Exposure of Protected and Unprotected Forest to Plant Invasions in the Eastern United States

by Kurt Riitters, Kevin M. Potter, Basil V. Iannone III, Christopher Oswalt, Qinfeng Guo and Songlin Fei

Forests 2018, 9(11), 723; https://doi.org/10.3390/f9110723 - 20 Nov 2018

Cited by 16 | Viewed by 4867

Abstract

Research Highlights: We demonstrate a macroscale framework combining an invasibility model with forest inventory data, and evaluate regional forest exposure to harmful invasive plants under different types of forest protection. Background and Objectives: Protected areas are a fundamental component of natural [...] Read more.

Research Highlights: We demonstrate a macroscale framework combining an invasibility model with forest inventory data, and evaluate regional forest exposure to harmful invasive plants under different types of forest protection. Background and Objectives: Protected areas are a fundamental component of natural resource conservation. The exposure of protected forests to invasive plants can impede achievement of conservation goals, and the effectiveness of protection for limiting forest invasions is uncertain. We conducted a macroscale assessment of the exposure of protected and unprotected forests to harmful invasive plants in the eastern United States. Materials and Methods: Invasibility (the probability that a forest site has been invaded) was estimated for 82,506 inventory plots from site and landscape attributes. The invaded forest area was estimated by using the inventory sample design to scale up plot invasibility estimates to all forest area. We compared the invasibility and the invaded forest area of seven categories of protection with that of de facto protected (publicly owned) forest and unprotected forest in 13 ecological provinces. Results: We estimate approximately 51% of the total forest area has been exposed to harmful invasive plants, including 30% of the protected forest, 38% of the de facto protected forest, and 56% of the unprotected forest. Based on cumulative invasibility, the relative exposure of protection categories depended on the assumed invasibility threshold. Based on the invaded forest area, the five least-exposed protection categories were wilderness area (13% invaded), national park (18%), sustainable use (26%), nature reserve (31%), and de facto protected Federal land (36%). Of the total uninvaded forest area, only 15% was protected and 14% had de facto protection. Conclusions: Any protection is better than none, and public ownership alone is as effective as some types of formal protection. Since most of the remaining uninvaded forest area is unprotected, landscape-level management strategies will provide the most opportunities to conserve it. Full article

(This article belongs to the Special Issue Impacts of Nonnative Species on the Health of Natural and Planted Forests)

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26 pages, 4851 KiB

Open AccessArticle

Refining Species Traits in a Dynamic Vegetation Model to Project the Impacts of Climate Change on Tropical Trees in Central Africa

by Marie Dury, Lenni Mertens, Adeline Fayolle, Hans Verbeeck, Alain Hambuckers and Louis François

Forests 2018, 9(11), 722; https://doi.org/10.3390/f9110722 - 20 Nov 2018

Cited by 12 | Viewed by 4105

Abstract

African tropical ecosystems and the services they provide to human society suffer from an increasing combined pressure of land use and climate change. How individual tropical tree species respond to climate change remains relatively unknown. In this study, we refined the species characterization [...] Read more.

African tropical ecosystems and the services they provide to human society suffer from an increasing combined pressure of land use and climate change. How individual tropical tree species respond to climate change remains relatively unknown. In this study, we refined the species characterization in the CARAIB (CARbon Assimilation In the Biosphere) dynamic vegetation model by replacing plant functional type morpho-physiological traits by species-specific traits. We focus on 12 tropical tree species selected for their importance in both the plant community and human society. We used CARAIB to simulate the current species net primary productivity (NPP), biomass and potential distribution and their changes in the future. Our results indicate that the use of species-specific traits does not necessarily result in an increase of predicted current NPPs. The model projections for the end of the century highlight the large uncertainties in the future of African tropical species. Projected changes in species distribution vary greatly with the general circulation model (GCM) and, to a lesser extent, with the concentration pathway. The question about long-term plant response to increasing CO₂ concentrations also leads to contrasting results. In absence of fertilization effect, species are exposed to climate change and might lose 25% of their current distribution under RCP8.5 (12.5% under RCP4.5), considering all the species and climatic scenarios. The vegetation model projects a mean biomass loss of −21.2% under RCP4.5 and −34.5% under RCP8.5. Potential range expansions, unpredictable due to migration limitations, are too limited for offsetting range contraction. By contrast, if the long-term species response to increasing [CO₂] is positive, the range reduction is limited to 5%. However, despite a mean biomass increase of 12.2%, a positive CO₂ feedback might not prevent tree dieback. Our analysis confirms that species will respond differently to new climatic and atmospheric conditions, which may induce new competition dynamics in the ecosystem and affect ecosystem services. Full article

(This article belongs to the Special Issue Modeling Tropical Forest Dynamics through Their Functional Traits in a Climate Change Century)

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1 pages, 608 KiB

Open AccessRetraction

Retraction: Ren, Z.B., et al. Spatio-Temporal Patterns of Urban Forest Basal Area under China’s Rapid Urban Expansion and Greening: Implications for Urban Green Infrastructure Management. Forest 2018, 9, 272–290

by Zhibin Ren and Hongxu Wei

Forests 2018, 9(11), 721; https://doi.org/10.3390/f9110721 - 20 Nov 2018

Cited by 1 | Viewed by 2664

Abstract

The Forests Editorial Office has been made aware that Table 2, Figure 2, Figure 7, and Figure 8 listed in the paper [...] Full article

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

17 pages, 2630 KiB

Open AccessArticle

Effect of Thinning on the Spatial Structure of a Larix gmelinii Rupr. Secondary Forest in the Greater Khingan Mountains

by Tian Zhang, Xibin Dong, Huiwen Guan, Yuan Meng, Jiafu Ruan and Zhiyong Wang

Forests 2018, 9(11), 720; https://doi.org/10.3390/f9110720 - 19 Nov 2018

Cited by 14 | Viewed by 3042

Abstract

Thinning is an important way to adjust and optimize the spatial structure of forests. The study of its impacts support a better understanding of the succession process of secondary forests after interference. To study the changes in forest spatial structure under different thinning [...] Read more.

Thinning is an important way to adjust and optimize the spatial structure of forests. The study of its impacts support a better understanding of the succession process of secondary forests after interference. To study the changes in forest spatial structure under different thinning intensities and stand densities, we considered five thinning intensities including unthinned (0%), low (3.4%, 6.2%, 12.5%), medium (16.8%, 20.9%, 25.5%), high (34.4%, 40.0%, 47.9%), and extra-high (50.6%, 59.9%, 67.3%) intensity. In addition, three different stand densities for each degree of thinning intensity. The results showed that the most horizontal distribution patterns after thinning were uniform distribution and near-uniform random distribution. Most of the trees were not mixed while several were mixed to an above medium degree. The effect on dominance of thinning was not significant and the overall plots were in the middle level. The tree density was in the sparse status. Competitive pressure on the reference tree was reduced. Thinning intensity and stand density affected stand spatial structure to different degrees. There were no obvious pattern under different thinning intensities and it was optimal at approximately 1600 trees/ha. As thinning intensity increased, the impact tended to decrease first and then increase under certain stand density. The improvement was greatest when thinning intensity was low. By analyzing the stand’s spatial structure after thinning, the unreasonableness of the stand’s spatial structure can be found, which provides the basis for optimizing management measures. We used the AHP-entropy to weigh the importance of each spatial structure parameter and we proposed a comprehensive distance evaluation index based on the optimal value obtained in order to perform a comprehensive evaluation of a forest’s spatial structure. Full article

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

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20 pages, 721 KiB

Open AccessArticle

Piecemeal Integration: Explaining and Understanding 60 Years of European Union Forest Policy-Making

by Helga Pülzl, Doris Wydra and Karl Hogl

Forests 2018, 9(11), 719; https://doi.org/10.3390/f9110719 - 19 Nov 2018

Cited by 14 | Viewed by 4463

Abstract

This article looks at forest policy as empirical case study of European integration. By applying different theoretical lenses of European integration approaches (neo-functionalism, liberal intergovernmentalism, three institutionalist approaches and constructivism), it seeks to explain and understand the integration of forest policy in the [...] Read more.

This article looks at forest policy as empirical case study of European integration. By applying different theoretical lenses of European integration approaches (neo-functionalism, liberal intergovernmentalism, three institutionalist approaches and constructivism), it seeks to explain and understand the integration of forest policy in the European Union during the policy’s emergence (1958 to 1960s), expansion (1970 to late 1990s) and stabilization period (late 1990s to now). The findings clearly show that, to a certain extent, all European integration theories have their merits for the analysis. However, none of the employed integration theories alone can explain all the relevant aspects of the broader developments in EU forest policy. No individual theory can help explain why forest policy developed only incrementally and why it has been weakly institutionalized. This article, therefore, argues to combine them so as to establish a clearer picture of the driving factors and constraints. As each of the grand theories has its weak spots, it is further argued that scholars of European studies should work across a broader theoretical spectrum as only this would allow light to be shed on blind spots in empirical investigation over longer time periods. Full article

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

24 pages, 2682 KiB

Open AccessArticle

Succession of Mite Assemblages (Acari, Mesostigmata) during Decomposition of Tree Leaves in Forest Stands Growing on Reclaimed Post-Mining Spoil Heap and Adjacent Forest Habitats

by Cezary K. Urbanowski, Paweł Horodecki, Jacek Kamczyc, Maciej Skorupski and Andrzej M. Jagodziński

Forests 2018, 9(11), 718; https://doi.org/10.3390/f9110718 - 19 Nov 2018

Cited by 18 | Viewed by 3887

Abstract

Mites significantly contribute, prevalently by vertical movement, to mixing of the organic layer with the mineral soil, thus they may be important in renewing soils. Our aim was to analyze the changes in abundance and species richness of mesostigmatid assemblages on decomposing leaves [...] Read more.

Mites significantly contribute, prevalently by vertical movement, to mixing of the organic layer with the mineral soil, thus they may be important in renewing soils. Our aim was to analyze the changes in abundance and species richness of mesostigmatid assemblages on decomposing leaves of Alnus glutinosa (L.) Gaertn., Betula pendula Roth, Pinus sylvestris L. and Quercus robur L. in pine and birch stands growing on a reclaimed spoil heap and adjacent forests. In December 2013, 1024 litterbags (mesh size = 1 mm) containing leaf litter of broadleaved and coniferous trees (mean initial dry weight per sample = 5.789 g) were laid out in the same number and kind in each of the two sites. Mites were extracted from litterbags which were collected every 3–6 months for 3 years. In total, 6466 mites were identified in 59 taxa. Total abundance was higher on forest habitats (5174 specimens) compared to the spoil (1292), and in birch compared to pine stands, both in forest (3345, 1829, respectively) and spoil habitats (981, 311). Throughout the experiment, mites were most abundant on oak litter samples (2063 specimens), while the remaining litter types had similar abundances (1455–1482). At the beginning of the experiment (3–6 months) mite abundance was very low, but was higher on forest habitats. The highest abundance was found after 9 months—144 specimens in pine stands on the spoil heap and 685 in birch stands on forest habitats. During the study, 49 taxa were found on forest and 29 on heap habitats. In birch stands, 37 and 22 taxa were found, whereas in pine 30 and 21, on forest and heap, respectively. The most frequent species on the heap were Amblyseius tubae Karg, Asca bicornis Canestrini et Fanzago, and Asca aphidioides Linneaeus, whereas in forest habitat—Zercon peltatus C.L. Koch, Veigaia nemorensis C.L. Koch, and Trachytes aegrota C.L. Koch. Habitat conditions, tree species and litter type significantly determined the mesostigmatid species composition, richness and abundance. By selection of dominant tree species during afforestation, it is possible to significantly affect the soil fauna composition, and thus indirectly the rate of decomposition. Full article

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

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16 pages, 2640 KiB

Open AccessArticle

Effects of Site Preparation Methods on the Establishment and Natural-Regeneration Traits of Scots Pines (Pinus sylvestris L.) in Northeastern Poland

by Marta Aleksandrowicz-Trzcińska, Stanisław Drozdowski, Marcin Studnicki and Henryk Żybura

Forests 2018, 9(11), 717; https://doi.org/10.3390/f9110717 - 19 Nov 2018

Cited by 12 | Viewed by 3016

Abstract

While some tree species can regenerate naturally without mechanical site preparation (MSP), Scots pine has been shown to benefit from this process. We compared three methods: using a double-mouldboard forest plough (FP), an active single-disc plough (AP), and a forest mill (FM), as [...] Read more.

While some tree species can regenerate naturally without mechanical site preparation (MSP), Scots pine has been shown to benefit from this process. We compared three methods: using a double-mouldboard forest plough (FP), an active single-disc plough (AP), and a forest mill (FM), as well as a no-MSP control, in terms of growth, survival and density of occurrence of pines during the first 4 years of natural regeneration. Moisture conditions were expressed via calculated de Martonne aridity indices, while the microhabitats generated via different MSP methods were further characterised by the total contents of N and C, and the C/N ratio, P₂O₅, and base cations, as well as bulk density and actual moisture. The trials showed inferior regeneration without MSP in terms of the density and cover of young pines. Any of the studied treatments influenced survival, though the best growth was achieved by seedlings using the FP and AP methods, while the best density and evenness results were obtained using AP. The factors most influencing regeneration features were high precipitation during the first growing season after sowing and reduced competition with other vegetation in the cleared area. This impact seems far more important than the capacity of different MSPs to produce differentiation in soil microhabitats in terms of nutrient status or bulk density. Full article

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

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13 pages, 2557 KiB

Open AccessArticle

Converting Larch Plantations to Larch-Walnut Mixed Stands: Effects of Spatial Distribution Pattern of Larch Plantations on the Rodent-Mediated Seed Dispersal of Juglans mandshurica

by Jing Wang, Qiaoling Yan, Ting Zhang, Deliang Lu, Jin Xie, Yirong Sun, Jinxin Zhang and Jiaojun Zhu

Forests 2018, 9(11), 716; https://doi.org/10.3390/f9110716 - 18 Nov 2018

Cited by 4 | Viewed by 3144

Abstract

Larch (Larix spp.) is planted after a clear-cut of secondary forests (SFs) to meet the timber demand of Northeast China. However, the declination of soil fertility and the acidification of surface runoff in larch plantations (LPs) resulting from mono-species composition have threatened [...] Read more.

Larch (Larix spp.) is planted after a clear-cut of secondary forests (SFs) to meet the timber demand of Northeast China. However, the declination of soil fertility and the acidification of surface runoff in larch plantations (LPs) resulting from mono-species composition have threatened the sustainable development of LPs. Converting pure LPs into larch-walnut mixed forests can solve those problems, in which it is crucial to promote the seed regeneration of Juglans mandshurica in LPs. The success of walnut seed regeneration is dependent on rodent removing seed away from mother trees and the dispersal processes rely on the stand structure. The spatial distribution pattern between LPs and SFs is a type of stand structure that might affect seed dispersal. There are two typical spatial patterns in Northeast China due to different topographical conditions, that is, contour type (C-T, LPs and SFs located at the same slope position and aspect) and downslope type (D-T, LPs located at the down slope of the adjacent SF in the same aspect). The objectives of our study were to verify the effects of the spatial distribution pattern of LPs on rodent-mediated seed dispersal and to determine the optimal spatial distribution type for seed dispersal. The field trial was conducted by releasing tagged J. mandshurica seeds at three stages of seed rain during two continuous growing seasons in two types of spatial distribution patterns for LPs. We found that contour type had a substantial advantage in the rodent-mediated seed dispersal, that is, the dispersal rate and the proportion of scatter-hoarded seeds in LPs of C-T stands were much higher than in D-T stands, respectively. These differences may be caused by the variation in the topographic factor for these two types of spatial distribution pattern of LPs. In the C-T stands, it was a translational motion for rodents to remove walnuts from SFs to LPs, which would be an energy efficient and favorable method of seed dispersal. Fluctuation of seed abundance had an effect on rodent behaviors and seed fates, that is, there was a faster dispersal rate and lower proportion of seeds in situ in the non-masting year of 2015 than in the masting year of 2016 and proportion of scatter-hoarded seeds reached the highest during the early stage and lowest at the middle stage of seed rain. Thus, the contour type of LPs with a favorable terrain advantage is potentially conducive to dispersing walnut seeds by rodents during early stage of seed rain and converting larch plantations into larch-walnut mixed forests. Full article

(This article belongs to the Special Issue Natural Plant Regeneration Ecology in Forest Ecosystems)

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35 pages, 6389 KiB

Open AccessArticle

Landscape Topoedaphic Features Create Refugia from Drought and Insect Disturbance in a Lodgepole and Whitebark Pine Forest

by Jennifer Cartwright

Forests 2018, 9(11), 715; https://doi.org/10.3390/f9110715 - 18 Nov 2018

Cited by 13 | Viewed by 5046

Abstract

Droughts and insect outbreaks are primary disturbance processes linking climate change to tree mortality in western North America. Refugia from these disturbances—locations where impacts are less severe relative to the surrounding landscape—may be priorities for conservation, restoration, and monitoring. In this study, hypotheses [...] Read more.

Droughts and insect outbreaks are primary disturbance processes linking climate change to tree mortality in western North America. Refugia from these disturbances—locations where impacts are less severe relative to the surrounding landscape—may be priorities for conservation, restoration, and monitoring. In this study, hypotheses concerning physical and biological processes supporting refugia were investigated by modelling the landscape controls on disturbance refugia that were identified using remotely sensed vegetation indicators. Refugia were identified at 30-m resolution using anomalies of Landsat-derived Normalized Difference Moisture Index in lodgepole and whitebark pine forests in southern Oregon, USA, in 2001 (a single-year drought with no insect outbreak) and 2009 (during a multi-year drought and severe outbreak of mountain pine beetle). Landscape controls on refugia (topographic, soil, and forest characteristics) were modeled using boosted regression trees. Landscape characteristics better explained and predicted refugia locations in 2009, when forest impacts were greater, than in 2001. Refugia in lodgepole and whitebark pine forests were generally associated with topographically shaded slopes, convergent environments such as valleys, areas of relatively low soil bulk density, and in thinner forest stands. In whitebark pine forest, refugia were associated with riparian areas along headwater streams. Spatial patterns in evapotranspiration, snowmelt dynamics, soil water storage, and drought-tolerance and insect-resistance abilities may help create refugia from drought and mountain pine beetle. Identification of the landscape characteristics supporting refugia can help forest managers target conservation resources in an era of climate-change exacerbation of droughts and insect outbreaks. Full article

(This article belongs to the Special Issue Ecology and Restoration of Whitebark Pine)

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15 pages, 5105 KiB

Open AccessArticle

A General Leaf Area Geometric Formula Exists for Plants—Evidence from the Simplified Gielis Equation

by Peijian Shi, David A. Ratkowsky, Yang Li, Lifang Zhang, Shuyan Lin and Johan Gielis

Forests 2018, 9(11), 714; https://doi.org/10.3390/f9110714 - 17 Nov 2018

Cited by 65 | Viewed by 11700

Abstract

Plant leaves exhibit diverse shapes that enable them to utilize a light resource maximally. If there were a general parametric model that could be used to calculate leaf area for different leaf shapes, it would help to elucidate the adaptive evolutional link among [...] Read more.

Plant leaves exhibit diverse shapes that enable them to utilize a light resource maximally. If there were a general parametric model that could be used to calculate leaf area for different leaf shapes, it would help to elucidate the adaptive evolutional link among plants with the same or similar leaf shapes. We propose a simplified version of the original Gielis equation (SGE), which was developed to describe a variety of object shapes ranging from a droplet to an arbitrary polygon. We used this equation to fit the leaf profiles of 53 species (among which, 48 bamboo plants, 5 woody plants, and 10 geographical populations of a woody plant), totaling 3310 leaves. A third parameter (namely, the floating ratio c in leaf length) was introduced to account for the case when the theoretical leaf length deviates from the observed leaf length. For most datasets, the estimates of c were greater than zero but less than 10%, indicating that the leaf length predicted by the SGE was usually smaller than the actual length. However, the predicted leaf areas approximated their actual values after considering the floating ratios in leaf length. For most datasets, the mean percent errors of leaf areas were lower than 6%, except for a pooled dataset with 42 bamboo species. For the elliptical, lanceolate, linear, obovate, and ovate shapes, although the SGE did not fit the leaf edge perfectly, after adjusting the parameter c, there were small deviations of the predicted leaf areas from the actual values. This illustrates that leaves with different shapes might have similar functional features for photosynthesis, since the leaf areas can be described by the same equation. The anisotropy expressed as a difference in leaf shape for some plants might be an adaptive response to enable them to adapt to different habitats. Full article

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

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21 pages, 19762 KiB

Open AccessArticle

Species Mixing Effects on Forest Productivity: A Case Study at Stand-, Species- and Tree-Level in the Netherlands

by Huicui Lu, Godefridus M. J. Mohren, Miren Del Río, Mart-Jan Schelhaas, Meike Bouwman and Frank J. Sterck

Forests 2018, 9(11), 713; https://doi.org/10.3390/f9110713 - 17 Nov 2018

Cited by 11 | Viewed by 5941

Abstract

Many monoculture forests have been converted to mixed-species forests in Europe over the last decades. The main reasons for this conversion were probably to increase productivity, including timber production, and enhance other ecosystem services, such as conservation of biodiversity and other nature values. [...] Read more.

Many monoculture forests have been converted to mixed-species forests in Europe over the last decades. The main reasons for this conversion were probably to increase productivity, including timber production, and enhance other ecosystem services, such as conservation of biodiversity and other nature values. This study was done by synthesizing results from studies carried out in Dutch mixed forests compared with monoculture stands and evaluating them in the perspective of the current theory. Then we explored possible mechanisms of higher productivity in mixed stands, in relation to the combination of species, stand age and soil fertility, and discussed possible consequences of forest management. The study covered five two-species mixtures and their corresponding monoculture stands from using long-term permanent forest plots over multiple decades as well as two inventories (around 2003 and 2013) across the entire Netherlands. These forest plot data were used together with empirical models at total stand level, species level and tree level. Overyielding in Douglas-fir–beech and pine–oak mixtures was maintained over time, probably owing to the intensive thinning and was achieved on the poorer soils. However, this overyielding was not always driven by fast-growing light-demanding species. On individual tree level, intra-specific competition was not necessarily stronger than inter-specific competition and this competitive reduction was less seen at lower soil fertility and dependent on species mixtures. Moreover, size-asymmetric competition for light was more associated with tree basal area growth than size-symmetric competition for soil resources. Overall, this study suggests a substantial potential of species mixing for increasing productivity and implies developing forest management strategies to convert monospecific forests to mixed-species forests that consider the complementarity in resource acquisition of tree species. Full article

(This article belongs to the Special Issue Competition and Facilitation in Mixed Species Forests)

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9 pages, 2734 KiB

Open AccessArticle

The Effects of Using Wood Chips and Slash in Reducing Sheet Erosion on Forest Road Slopes

by Yilmaz Turk

Forests 2018, 9(11), 712; https://doi.org/10.3390/f9110712 - 16 Nov 2018

Cited by 5 | Viewed by 3881

Abstract

This study compared the use of wood chips and slash to reduce the loss of sediment on newly constructed forest road slopes and investigated the annual amount of sediment loss on bare forest road slopes. A runoff block (sample field) was established for [...] Read more.

This study compared the use of wood chips and slash to reduce the loss of sediment on newly constructed forest road slopes and investigated the annual amount of sediment loss on bare forest road slopes. A runoff block (sample field) was established for each of the four designated test sites (two cutslopes and two fillslopes). Each block had three runoff plots. One of the runoff plots was left empty for the control (CNT), while wood chips (C) and slash (S), respectively, were deposited in the other two. A total of 108 water samples were taken from the test sites and the amount of their suspended sediment calculated in the laboratory. As a result of this study, it was determined that the amount of soil loss in the control plots was about 1.26 times higher than in the slash plots and 2.21 times higher than in the wood chips plots. According to the results of variance analysis on the amounts of sediment, a statistically significant difference was found between the suspended sediment quantities transported on the road slopes (p < 0.05). However, no statistically significant difference between the suspended sediment quantities transported in the plots and the other variables of aspect, gradient or road slope was revealed by the t-test (p > 0.05). Full article

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

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14 pages, 1722 KiB

Open AccessArticle

Allelopathic Effects of Aqueous Leaf Extracts from Four Shrub Species on Seed Germination and Initial Growth of Amygdalus pedunculata Pall.

by Xiuqing Wang, Jinxin Wang, Ruiqi Zhang, You Huang, Shulin Feng, Xu Ma, Yuyu Zhang, Ashim Sikdar and Rana Roy

Forests 2018, 9(11), 711; https://doi.org/10.3390/f9110711 - 16 Nov 2018

Cited by 21 | Viewed by 3973

Abstract

This study aimed to screen out the shrub species which can promote the seed germination and seedling growth of Amygdalus pedunculata Pall. and offer insight for ecological environment governance of the coal mines subsidence area in Mu Us Sandy Land, Yulin City of [...] Read more.

This study aimed to screen out the shrub species which can promote the seed germination and seedling growth of Amygdalus pedunculata Pall. and offer insight for ecological environment governance of the coal mines subsidence area in Mu Us Sandy Land, Yulin City of Shaanxi Province. The indoor bioassay method was used to study the aqueous leaf extracts from Amorpha fruticosa Linn., Hedysarum mongolicum Turez., Sabina vulgaris Ant., and Hippophae rhamnoides Linn. under different concentration gradients to examine seed germination, initial growth, and physiological and biochemical of two Amygdalus pedunculata varieties (YY-1 from Yuyang County (YY) and SM-6 from Shenmu County (SM), Shaanxi Province, China). The results showed that with aqueous leaf extracts concentrations at lower concentrations of 0.025 (T1) and 0.05 g·mL⁻¹ (T2) from A. fruticosa, H. mongolicum, and S. vulgaris significantly promoted seed germination and seedling growth of two A. pedunculata varieties. Moreover, H. rhamnoides aqueous leaf extracts had the strongest inhibitory effect on seed germination and seedling growth of A. pedunculata, and death occurred at concentrations of 0.15 (T4) and 0.20 g·mL⁻¹ (T5). The enzyme activity and chlorophyll content of the A. pedunculata leaves decreased with an increase in the aqueous leaf extracts concentration of the four shrubs; the change trend of malondialdehyde content was the opposite. Root activity of the A. pedunculata increased and then decreased. The H. mongolicum and S. vulgaris are the most suitable mixed tree species for YY-1, while H. mongolicum and A. fruticosa are the most suitable mixed tree species for SM-6 at a relatively low density with more security. The results provide a theoretical basis and technical support for the establishment of an artificial mixed forest of A. pedunculata in the coal mine subsidence area of Mu Us Sandy Land. Full article

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

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15 pages, 2681 KiB

Open AccessArticle

Characterization of Phosphorus in Subtropical Coastal Sand Dune Forest Soils

by Chiao-Wen Lin, Guanglong Tian, Chung-Wen Pai and Chih-Yu Chiu

Forests 2018, 9(11), 710; https://doi.org/10.3390/f9110710 - 15 Nov 2018

Cited by 4 | Viewed by 2750

Abstract

Continuous research into the availability of phosphorus (P) in forest soil is critical for the sustainable management of forest ecosystems. In this study, we used sequential chemical extraction and ³¹P-nuclear magnetic resonance spectroscopy (³¹P-NMR) to evaluate the form and distribution [...] Read more.

Continuous research into the availability of phosphorus (P) in forest soil is critical for the sustainable management of forest ecosystems. In this study, we used sequential chemical extraction and ³¹P-nuclear magnetic resonance spectroscopy (³¹P-NMR) to evaluate the form and distribution of inorganic P (P_i) and organic P (P_o) in Casuarina forest soils of a subtropical coastal sand dune in Houlong, Taiwan. The soil samples were collected from humic (+2–0 cm) and mineral layers (mineral-I: 0–10, mineral-II: 10–20 cm) at two topographic locations (upland and lowland) with different elevations. Sequential chemical extraction revealed that the NaOH-P_o fraction, as moderately recalcitrant P, was the dominant form in humic and mineral-I layers in both upland and lowland soils, whereas the cHCl-P_i fraction was the dominant form in the mineral-II layer. The resistant P content, including NaOH-P_i, HCl-P_i, cHCl-P_i, and cHCl-P_o fractions, was higher in the upland than in the lowland. However, the labile P content, NaHCO₃-P_o, showed the opposite pattern. The content of resistant P_i (NaOH-P_i, HCl-P_i, and cHCl-P_i) increased significantly with depth, but that of labile P_i (resin-P_i and NaHCO₃-P_i) and recalcitrant P_o (NaHCO₃-P_o, NaOH-P_o, and cHCl-P_o) decreased significantly with depth at both locations. ³¹P-NMR spectroscopy revealed inorganic orthophosphate and monoesters-P as the major forms in this area. The proportions of P_i and P_o evaluated by sequential chemical extraction and ³¹P-NMR spectroscopy were basically consistent. The results indicate that the soils were in weathered conditions. Furthermore, the P distribution and forms in this coastal sand dune landscape significantly differed between the upland and lowland because of the variation in elevation and eolian aggradation effects. Full article

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

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17 pages, 8970 KiB

Open AccessArticle

Application of Terrestrial Laser Scanner to Evaluate the Influence of Root Collar Geometry on Stump Height after Mechanized Forest Operations

by Eric R. Labelle, Joachim B. Heppelmann and Herbert Borchert

Forests 2018, 9(11), 709; https://doi.org/10.3390/f9110709 - 15 Nov 2018

Cited by 3 | Viewed by 3153

Abstract

The height of tree stumps following mechanized forest operations can be influenced by machine-, tree-, terrain-, and operator-related characteristics. High stumps may pose different economic and technical disadvantages. Aside from a reduction in product recovery (often associated with sawlog potential), leaving high stumps [...] Read more.

The height of tree stumps following mechanized forest operations can be influenced by machine-, tree-, terrain-, and operator-related characteristics. High stumps may pose different economic and technical disadvantages. Aside from a reduction in product recovery (often associated with sawlog potential), leaving high stumps can complicate future entries if smaller equipment with low ground clearance is used, particularly in the case where new machine operating trails are required. The objective of this exploratory study was to examine if correlations existed between the height of tree stumps following mechanized harvesting and the shape of the above-ground root collar, stump diameter, and distance to the machine operating trail. In total, 202 sample stumps of Norway spruce (Picea abies (L.) Karst.) and the surrounding terrain were scanned with a terrestrial laser scanner. The collected data was processed into a 3D-model and then analyzed. Stump height was compared with different characteristics such as stump diameter at the cut surface, distance to the machine operating trail, number of visible root flares per stump, and the root collar. The number of root flares per stump had a positive influence on stump diameter and height, showing a general trend of increasing diameter and height with the increasing number of root flares. Root angles also had an influence on the stump diameter. The diameter of a stump and the shape of the root collar at the cut surface together had a significant effect on stump height and the model reported explained half of the variation of stump heights. Taken together, these findings suggest that other factors than the ones studied can also contribute in influencing stump height during mechanized harvesting operations. Further investigations, including pre- and post-harvest scans of trees selected for removal, are warranted. Full article

(This article belongs to the Special Issue 3D Remote Sensing Applications in Forest Ecology: Composition, Structure and Function)

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19 pages, 4555 KiB

Open AccessArticle

Assessing the Minimum Number of Time Since Last Fire Sample-Points Required to Estimate the Fire Cycle: Influences of Fire Rotation Length and Study Area Scale

by Xinyuan Wei and Chris P. S. Larsen

Forests 2018, 9(11), 708; https://doi.org/10.3390/f9110708 - 14 Nov 2018

Cited by 11 | Viewed by 3241

Abstract

Boreal forest fire history is typically reconstructed using tree-ring based time since last fire (TSLF) frequency distributions from across the landscape. We employed stochastic landscape fire simulations to assess how large a study area and how many TSLF sample-points are required to estimate [...] Read more.

Boreal forest fire history is typically reconstructed using tree-ring based time since last fire (TSLF) frequency distributions from across the landscape. We employed stochastic landscape fire simulations to assess how large a study area and how many TSLF sample-points are required to estimate the fire cycle (FC) within a given accuracy, and if those requirements change with length of the simulated fire rotation (FR_S). FR_S is calculated from simulated fire-year maps used to create the TSLF map, and is the “true” measure of fire history that FC estimates should equal. Fire-year maps were created by (i) using a spatially homogenous landscape, (ii) imposing large variations in annual area burned, and (iii) having no age-related change in the hazard of burning. We found that study areas should be ≥3× the size of largest total annual area burned, with smaller-scale areas having a bias that cannot be fixed by employing more samples. For a study area scale of 3×, a FC estimate with an error <10% was obtained with 187 TSLF samples at 0.81 samples per 100 km². FC estimates were not biased in study area scales that were ≥3×, but smaller-scale areas with a short FR_S had an overestimated FC and smaller-scale areas with a long FR_S had an underestimated FC. Site specific variations in environmental- and age-related variations in the hazard of burning may require more sample-points; site specific simulations should thus be conducted to determine sample numbers before conducting a TSLF field study. Full article

(This article belongs to the Special Issue Fire Effects and Management in Forests)

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23 pages, 3417 KiB

Open AccessArticle

Assessing the Long-Term Ecosystem Productivity Benefits and Potential Impacts of Forests Re-Established on a Mine Tailings Site

by Juha M. Metsaranta, Suzanne Beauchemin, Sean Langley, Bryan Tisch and Phyllis Dale

Forests 2018, 9(11), 707; https://doi.org/10.3390/f9110707 - 14 Nov 2018

Cited by 7 | Viewed by 4015

Abstract

Restoring sites disturbed by industrial activity to a forested condition can ensure the continued provision of economic and ecosystem services from these areas. Impounded mine tailings are particularly challenging sites, and positive benefits of establishing trees must be balanced against risks associated with [...] Read more.

Restoring sites disturbed by industrial activity to a forested condition can ensure the continued provision of economic and ecosystem services from these areas. Impounded mine tailings are particularly challenging sites, and positive benefits of establishing trees must be balanced against risks associated with metal contamination, ongoing tailings stability, and the possibility of acid mine drainage. We used a hybrid biometric modelling approach based on dendrochronological reconstruction to retrospectively (1980–2015) quantify productivity and carbon dynamics of pine plantations growing on impounded mine tailings at the Vale waste management facility near Sudbury, Canada. Historical reclamation practices had remediated conditions sufficiently to allow conifer plantation establishment in the late 1970s. The revegetated sites were highly productive, when compared to reference conditions based on site index, wood volume growth, and ecosystem production, congruent with other studies showing that forests on revegetated post mining sites can be highly productive. However, metal concentrations in the forest floor were high, and further research is warranted to evaluate ecosystem impacts. Due to the requirement for energy-intensive inputs, we estimated that it took 12 years or more to recover the emissions associated with the revegetation process through C accumulated in biomass and soil at the revegetated sites. Full article

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

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22 pages, 6342 KiB

Open AccessArticle

Assessing Spatial Equity and Accessibility of Public Green Spaces in Aleppo City, Syria

by Hussein Almohamad, Anna Lisa Knaack and Badriah Mohammed Habib

Forests 2018, 9(11), 706; https://doi.org/10.3390/f9110706 - 14 Nov 2018

Cited by 33 | Viewed by 7420

Abstract

This paper examines the accessibility of urban green spaces within the Syrian city of Aleppo before the civil war using an environmental justice approach by indicating the current state of the parameters proximity and quantity in relation to the socioeconomic status of the [...] Read more.

This paper examines the accessibility of urban green spaces within the Syrian city of Aleppo before the civil war using an environmental justice approach by indicating the current state of the parameters proximity and quantity in relation to the socioeconomic status of the inhabitants. Therefore, we conducted the average nearest neighbour analysis, facilities over and under coverage analysis, network analysis and a one-way analysis of variance (ANOVA) test followed by a post-hoc Tukey honestly significant difference (HSD) test. The findings clearly indicate that the spatial pattern of the distribution of public parks facilities was significantly clustered (p-value < 0.0001), with a z-score of −16.4. Several neighbourhoods within the western and central parts of the city were identified to have a higher density of facilities, while the majority of the neighbourhoods located in the marginal parts in eastern Aleppo (low income) lack access to urban green spaces. The hierarchy-wise analysis reveals a strong deficit of urban green spaces at lower hierarchies, for example pocket parks and neighbourhood parks, while access to quarter parks and district parks is high. The urban green spaces at higher hierarchies are located in high and middle socioeconomic status areas. Regarding social segregation in park distribution and their accessibility, the data showed that high income neighbourhoods enjoy a significantly higher percentage of park facilities. The approach presented in this paper offers a generic method for the future development of public green spaces for balanced and sustainable planning. Full article

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

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17 pages, 2783 KiB

Open AccessArticle

Assessment and Monitoring Protocols to Guarantee the Maintenance of Biodiversity in Certified Forests: A Case Study for FSC (Forest Stewardship Council) Forests in Southwestern Spain

by Antonio J. Sánchez-Almendro, Pablo J. Hidalgo, Rosario Galán, José M. Carrasco and Javier López-Tirado

Forests 2018, 9(11), 705; https://doi.org/10.3390/f9110705 - 14 Nov 2018

Cited by 8 | Viewed by 3024

Abstract

(1) Biodiversity, sustainable development and nature conservation are fundamental issues nowadays. All companies, administrations, governments and international organisations take these issues into consideration. Sustainable forest management always requires a compromise between profitability and conservation and in this fragile equilibrium, forest certification plays a [...] Read more.

(1) Biodiversity, sustainable development and nature conservation are fundamental issues nowadays. All companies, administrations, governments and international organisations take these issues into consideration. Sustainable forest management always requires a compromise between profitability and conservation and in this fragile equilibrium, forest certification plays a key scheme. This sustainable management is of great importance in the European Union (EU), with the Forest Stewardship Council playing a fundamental role in forest certification. This certification forms the basis of the ecosystem conservation and improvement strategy in Ence, Energía y Celulosa, the leading company dedicated to the production of eucalyptus in Spain; (2) A three-phase protocol (identification of High Conservation Values, assessment of conservation areas and monitoring program), has been developed, providing clear, objective criteria, particularly concerning FSC (Forest Stewardship Council) Principle 9, the primary goal being the development and application of these objective criteria in the Ence conservation areas in the province of Huelva (Spain). One of the main criteria for habitat classification was correspondence with the habitats listed in Annex I of the Habitats Directive. The compatibility between forest exploitation management and conservation proposed by the Natura 2000 network encouraged us to use this methodology for the identification, classification and assessment of High Conservation Values considered in FSC forest certification: Principle 9; (3) The study encompasses 183 forest management units covering 52,022 ha, with a total of 11,847.45 ha being identified as High Conservation Value Areas. Through the identification and assessment of the conservation areas, the described methodology played a crucial role in demonstrating the positive impact of Ence’s certified forest management on the conservation of biological diversity; (4) This study demonstrates that an objective and reliable identification, assessment and monitoring methodology, with a proven high degree of accuracy in the location and characterisation of interesting and representative habitats in the region, can be implemented. Due to its objectivity, this strategy can be easily applied to other European sustainable forest management sites and possibly to other countries outside the EU. Full article

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

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16 pages, 3444 KiB

Open AccessArticle

Long-Term Abandonment of Forest Management Has a Strong Impact on Tree Morphology and Wood Volume Allocation Pattern of European Beech (Fagus sylvatica L.)

by Louis Georgi, Matthias Kunz, Andreas Fichtner, Werner Härdtle, Karl Friedrich Reich, Knut Sturm, Torsten Welle and Goddert von Oheimb

Forests 2018, 9(11), 704; https://doi.org/10.3390/f9110704 - 13 Nov 2018

Cited by 11 | Viewed by 6100

Abstract

The three-dimensional (3D) morphology of individual trees is critical for light interception, growth, stability and interactions with the local environment. Forest management intensity is a key driver of tree morphology, but how the long-term abandonment of silvicultural measures impacts trunk and crown morphological [...] Read more.

The three-dimensional (3D) morphology of individual trees is critical for light interception, growth, stability and interactions with the local environment. Forest management intensity is a key driver of tree morphology, but how the long-term abandonment of silvicultural measures impacts trunk and crown morphological traits is not fully understood. Here, we take advantage of a long management intensity gradient combined with a high-resolution terrestrial laser scanning (TLS) approach to explore how management history affects the 3D structure of mature beech (Fagus sylvatica L.) trees. The management gradient ranged from long-term (>50 years) and short-term (>20 years) unmanaged to extensively and intensively managed beech stands. We determined 28 morphological traits and quantified the vertical distribution of wood volume along the trunk. We evaluated the differences in tree morphological traits between study stands using Tukey’s HSD test. Our results show that 93% of the investigated morphological traits differed significantly between the study stands. Significant differences, however, emerged most strongly in the stand where forest management had ceased >50 years ago. Furthermore, we found that the vertical distribution of trunk wood volume was highly responsive between stands with different management intensity, leading to a 67% higher taper top height and 30% lower taper of beech trees growing in long-term unmanaged stands compared to those in short-term unmanaged or managed stands. These results have important implications for management intensity decisions. It is suggested that the economic value of individual beech trees from long-term unmanaged forests can be expected to be very high. This might also translate to beech forests that are extensively managed, but we found that a few decades of implementation of such a silvicultural system is not sufficient to cause significant differences when compared to intensively managed stands. Furthermore, TLS-based high-resolution analyses of trunk and crown traits play a crucial role in the ability to better understand or predict tree growth responses to the current drivers of global change. Full article

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

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16 pages, 6943 KiB

Open AccessArticle

Bending Stiffness, Load-Bearing Capacity and Flexural Rigidity of Slender Hybrid Wood-Based Beams

by Barbara Šubic, Gorazd Fajdiga and Jože Lopatič

Forests 2018, 9(11), 703; https://doi.org/10.3390/f9110703 - 13 Nov 2018

Cited by 13 | Viewed by 4529

Abstract

Modern architecture suggests the use of opened spaces with large transparent envelope surfaces. Therefore, windows of long widths and large heights are needed. In order to withstand the wind loads, such wooden windows can be reinforced with stiffer materials, such as aluminium (Al), [...] Read more.

Modern architecture suggests the use of opened spaces with large transparent envelope surfaces. Therefore, windows of long widths and large heights are needed. In order to withstand the wind loads, such wooden windows can be reinforced with stiffer materials, such as aluminium (Al), glass-fibre reinforced polymer (GFRP), and carbon-fibre reinforced polymer (CFRP). The bending stiffness, load-bearing capacity, and flexural rigidity of hybrid beams, reinforced with aluminium, were compared through experimental analysis, using a four-point bending tests method, with those of reference wooden beams. The largest increases in bending stiffness (29%–39%), load-bearing capacity (33%–45%), and flexural rigidity (43%–50%) were observed in the case of the hybrid beams, with the highest percentage of reinforcements (12.9%—six reinforcements in their tensile and six reinforcements in their compressive zone). The results of the experiments confirmed the high potential of using hybrid beams to produce large wooden windows, for different wind zones, worldwide. Full article

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

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16 pages, 4506 KiB

Open AccessArticle

LiDAR-Based Regional Inventory of Tall Trees—Wellington, New Zealand

by Jan Zörner, John R. Dymond, James D. Shepherd, Susan K. Wiser and Ben Jolly

Forests 2018, 9(11), 702; https://doi.org/10.3390/f9110702 - 13 Nov 2018

Cited by 23 | Viewed by 6769

Abstract

Indigenous forests cover 23.9% of New Zealand’s land area and provide highly valued ecosystem services, including climate regulation, habitat for native biota, regulation of soil erosion and recreation. Despite their importance, information on the number of tall trees and the tree height distribution [...] Read more.

Indigenous forests cover 23.9% of New Zealand’s land area and provide highly valued ecosystem services, including climate regulation, habitat for native biota, regulation of soil erosion and recreation. Despite their importance, information on the number of tall trees and the tree height distribution across different forest classes is scarce. We present the first region-wide spatial inventory of tall trees (>30 m) based on airborne LiDAR (Light Detection and Ranging) measurements in New Zealand—covering the Greater Wellington region. This region has 159,000 ha of indigenous forest, primarily on steep mountainous land. We implement a high-performance tree mapping algorithm that uses local maxima in a canopy height model (CHM) as initial tree locations and accurately identifies the tree top positions by combining a raster-based tree crown delineation approach with information from the digital surface and terrain models. Our algorithm includes a check and correction for over-estimated heights of trees on very steep terrain such as on cliff edges. The number of tall trees (>30 m) occurring in indigenous forest in the Wellington Region is estimated to be 286,041 (±1%) and the number of giant trees (>40 m tall) is estimated to be 7340 (±1%). Stereo-analysis of aerial photographs was used to determine the accuracy of the automated tree mapping. The giant trees are mainly in the beech-broadleaved-podocarp and broadleaved-podocarp forests, with density being 0.04 and 0.12 (trees per hectare) respectively. The inventory of tall trees in the Wellington Region established here improves the characterization of indigenous forests for management and provides a useful baseline for long-term monitoring of forest conditions. Our tree top detection scheme provides a simple and fast method to accurately map overstory trees in flat as well as mountainous areas and can be directly applied to improve existing and build new tree inventories in regions where LiDAR data is available. Full article

(This article belongs to the Special Issue Remote Sensing Technology Applications in Forestry and REDD+)

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13 pages, 997 KiB

Open AccessArticle

Evaluating the Contribution of Trees outside Forests and Small Open Areas to the Italian Landscape Diversification during the Last Decades

by Lorenzo Sallustio, Marco Di Cristofaro, Maaz Maqsood Hashmi, Matteo Vizzarri, Tommaso Sitzia, Bruno Lasserre and Marco Marchetti

Forests 2018, 9(11), 701; https://doi.org/10.3390/f9110701 - 12 Nov 2018

Cited by 8 | Viewed by 3131

Abstract

Land use by humans strongly alters the landscape mosaic, either by reducing or increasing its heterogeneity. One of the most recent and widespread land use changes in Europe has been the spontaneous reforestation of marginal agricultural lands. These primarily affected small landscape patches, [...] Read more.

Land use by humans strongly alters the landscape mosaic, either by reducing or increasing its heterogeneity. One of the most recent and widespread land use changes in Europe has been the spontaneous reforestation of marginal agricultural lands. These primarily affected small landscape patches, such as trees outside forests (TOF) and small open areas (SOA), often represent the most diversifying features of landscape’ structures. Nevertheless, only small-scale studies can be found in the literature and thus it remains a relatively unexplored issue. Integrating inventory and cartographic approaches, this work assesses changes in abundance, coverage, and average size of small patches in Italy between 1990 and 2013. Main results showed an overall increase in number and coverage of small patches during the reference period. The average patch size remains unaltered for TOF but decreases significantly for SOA, due to trees encroachment and canopy cover increasing in forests. Our findings confirm the important changes in Mediterranean land mosaics and contribute to a better understanding of current conditions and recent trends regarding TOF and SOA. The integrated approach has proven to be helpful for the large-scale assessment of small patches dynamics, representing a viable monitoring tool to encourage the inclusion of small patches in landscape policy and planning. Full article

(This article belongs to the Special Issue Emergent Trends in Managed Landscapes: Land Change, Forest Transformation, and Resource Management in the 21st Century)

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15 pages, 2866 KiB

Open AccessArticle

Embryo Development, Seed Germination, and the Kind of Dormancy of Ginkgo biloba L.

by Jing Feng, Yongbao Shen, Fenghou Shi and Chengzhong Li

Forests 2018, 9(11), 700; https://doi.org/10.3390/f9110700 - 11 Nov 2018

Cited by 12 | Viewed by 10810

Abstract

The embryos of Ginkgo biloba L. are generally reported to undergo after-ripening and be underdeveloped at the time of dispersal, which suggests that the seeds have morphological dormancy (MD) or morphological physiological dormancy (MPD). The aim of this work is to determine whether [...] Read more.

The embryos of Ginkgo biloba L. are generally reported to undergo after-ripening and be underdeveloped at the time of dispersal, which suggests that the seeds have morphological dormancy (MD) or morphological physiological dormancy (MPD). The aim of this work is to determine whether embryos of a G. biloba population are well-developed at the time of seed dispersal, and whether the seeds are dormant or not. From 8 September, which was the 140th day after flowering (140 DAF), seeds were collected separately from trees (T) and the ground (G) every 10 days until 7 December (230 DAF), resulting in a total of 10 samples. The changes in vertical diameter, transverse diameter, fresh weight, water content, and embryo length during seed development were measured. Simultaneously, the effects of different temperatures (15, 25, 30, and 35 °C) on seed germination, dormancy, and germination characteristics of G. biloba seeds were studied. Results showed that the embryos of G. biloba seeds were well developed and had no morphological dormancy. On 18 September (150 DAF), embryos were visible with a length of 2.5 mm. On 7 December (230 DAF), at the time of seed dispersal, their length was 17.1 mm. The germination percentage of the isolated embryos and seeds increased as the delay in seed collection increased, but there was no significant difference between T and G (p > 0.05). On 7 December (230 DAF), the germination of the isolated embryos reached 98%, indicating that the embryos were nondormant. Without pretreatment, seed germination was 82.57% within four weeks at 25 °C. Furthermore, the germination test at different temperatures showed the highest germination percentage at 30 °C (84.82%). Obviously, the G. biloba seeds were nondormant. The mean germination time (MGT) of the seeds at 30 and 35 °C was significantly lower than that of the seeds at 15 and 25 °C, and the speed of germination (SG) was significantly higher than that of the seeds at 15 and 25 °C. Although there was no significant difference in the seed-germination percentage between 30 and 35 °C, a portion of the seeds (9.5%) rotted at 35 °C. Therefore, 30 °C was the most favorable germination temperature for G. biloba seeds. This is the first study that reports G. biloba seeds with no dormancy. Full article

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

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18 pages, 4233 KiB

Open AccessArticle

Cloning and Expression of the Chitinase Encoded by ChiKJ406136 from Streptomyces Sampsonii (Millard & Burr) Waksman KJ40 and Its Antifungal Effect

by Shujiang Li, Boyang Zhang, Hanmingyue Zhu and Tianhui Zhu

Forests 2018, 9(11), 699; https://doi.org/10.3390/f9110699 - 11 Nov 2018

Cited by 16 | Viewed by 4870

Abstract

The present study demonstrated that the chitinase gene ChiKJ406136 of Streptomyces sampsonii (Millard & Burr) Waksman KJ40 could be cloned using a PCR protocol and expressed in Escherichia coli (Migula) Castellani & Chalmers BL21 (DE3), and the recombinant protein had antifungal effect [...] Read more.

The present study demonstrated that the chitinase gene ChiKJ406136 of Streptomyces sampsonii (Millard & Burr) Waksman KJ40 could be cloned using a PCR protocol and expressed in Escherichia coli (Migula) Castellani & Chalmers BL21 (DE3), and the recombinant protein had antifungal effect on four forest pathogens (Cylindrocladium scoparium Morgan, Cryphonectria parasitica (Murrill) Barr, Neofusicoccum parvum Crous, and Fusarium oxysporum Schl.) and also had the biological control effects on Eucalyptus robusta Smith leaf blight, Castanea mollissima BL. blight, Juglans regia L. blight and J. regia root rot. The results showed that ChiKJ406136 was efficiently expressed and a 48 kilodalton (kDa) recombinant protein was obtained. No significant change in protein production was observed in the presence of different concentrations of IPTG (isopropyl-b-D-thio-galactoside). The purified protein yield was greatest in the 150 mmol/L imidazole elution fraction, and the chitinase activities of the crude protein and purified protein solutions were 0.045 and 0.033 U/mL, respectively. The antifungal effects indicated that mycelial cells of the four fungi were disrupted, and the control effects of the chitinase on four forest diseases showed significant differences among the undiluted 10- and 20-fold dilutions and the control. The undiluted solution exhibited best effect. The results of this study provide a foundation for the use of S. sampsonii as a biocontrol agent and provides a new source for the chitinase gene, providing a theoretical basis for its application. Full article

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

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Forests, Volume 9, Issue 11 (November 2018) – 68 articles

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