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Volume 12
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Forests, Volume 12, Issue 4 (April 2021) – 132 articles

Cover Story (view full-size image): The Laurentian Great Lakes Basin of eastern North America is the largest surface freshwater ecosystem in the world, containing 20% of global freshwater supply and 95% of the United States’ surface freshwater. The Great Lakes Restoration Initiative (GLRI) was enacted to protect and restore Great Lakes ecosystems. With GLRI funding, USDA Forest Service researchers and their partners developed the world’s largest regional phytotechnologies network, consisting of sixteen agroforestry phytoremediation buffer systems (i.e., phyto buffers) in the Lake Superior and Lake Michigan watersheds. These phyto buffers enhance the potential for phytoremediation best management practices that are geographically robust, being regionally designed, yet globally relevant. View this paper
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14 pages, 3164 KiB  
Article
Raffaelea quercina sp. nov. Associated with Cork Oak (Quercus suber L.) Decline in Portugal
by Maria L. Inácio, José Marcelino, Arlindo Lima, Edmundo Sousa and Filomena Nóbrega
Forests 2021, 12(4), 513; https://doi.org/10.3390/f12040513 - 20 Apr 2021
Cited by 4 | Viewed by 3424
Abstract
Research Highlights: Raffaelea quercina sp. nov. is an ophiostomatoid fungus isolated from the ambrosia beetle Platypus cylindrus. The species occurs in symptomatic Portuguese cork oak trees, (Quercus suber L.), exhibiting vegetative decline. Background and Objectives: Quercus suber L. is a species [...] Read more.
Research Highlights: Raffaelea quercina sp. nov. is an ophiostomatoid fungus isolated from the ambrosia beetle Platypus cylindrus. The species occurs in symptomatic Portuguese cork oak trees, (Quercus suber L.), exhibiting vegetative decline. Background and Objectives: Quercus suber L. is a species restricted to the Mediterranean basin, of special economic importance as it constitutes the crucial raw material for the cork production industry, in particular for Portugal, the world’s leading producer. Over the last three decades a progressive and alarming decline of cork oak trees has been observed across its distribution area, including Portugal. The ambrosia beetle Platypus cylindrus, commonly known as the oak pinhole borer, establishes symbiotic relationships with fungi from which it depends for survival and for oak colonization. Some of these fungi are ophiostomatoid species of the Raffaelea genus, known as ambrosia fungi associated with ambrosia beetles. Some Raffaelea species exhibit phytopathogenic activity causing wilting and/or death of trees. The objective of the present study is to identify the association between P. cylindrus and Raffaelea species in Portuguese cork oak stands showing symptoms of disease and decline. Materials and Methods: A total of 300 adult insects were collected as they emerged from cork oak logs, sampled from symptomatic trees. Axenic isolates of Raffaelea species were obtained from the beetles and their galleries in the trunks and identified based on morphological features and molecular analysis of the SSU and LSU rDNA regions. Results: Two Raffaelea species were identified, i.e., R. montetyi and a novel Raffaelea species closely related to R. canadensis. The novel species is morphologically and genetically characterized in this study, and erected as Raffaelea quercina M.L. Inácio, E. Sousa & F. Nóbrega, sp. nov. Raffaelea quercina constitutes a new phytopathogenic fungal species associated with P. cylindrus and cork oak trees exhibiting symptoms of vegetative decline. Conclusions: Raffaelea species appear to have a significant role in cork oak decline. Future research on the association between P. cylindrus and Raffaelea species, encompassing the trans-European and North African wide-range of cork oak stands, would further clarify the relationships between ambrosia beetles, associated fungi and cork oak decline, contributing to a better understanding of the phenomena and for strategies aiming to halt the continuous decline of the unique cork oak stands enclosed in the Mediterranean basin. Full article
(This article belongs to the Special Issue Insects as Vectors of Forest Diseases)
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21 pages, 3827 KiB  
Article
Radial Variation of Wood Anatomical Properties Determines the Demarcation of Juvenile-Mature Wood in Schima superba
by Yunpeng Wang, Rui Zhang and Zhichun Zhou
Forests 2021, 12(4), 512; https://doi.org/10.3390/f12040512 - 20 Apr 2021
Cited by 13 | Viewed by 3293
Abstract
Schima superba is a precious broadleaf tree species that produces excellent timber. Analyzing the radial variation of wood anatomical properties within stems and determining the boundary between the juvenile and mature wood can provide a theoretical basis for the breeding and cultivation of [...] Read more.
Schima superba is a precious broadleaf tree species that produces excellent timber. Analyzing the radial variation of wood anatomical properties within stems and determining the boundary between the juvenile and mature wood can provide a theoretical basis for the breeding and cultivation of S. superba. Herein, 30 54-year-old trees were used to analyze the radial variation of wood anatomical properties qualitatively. The correlation among wood properties was analyzed. On this basis, four types of model were used to predict the wood properties quantitatively, and the optimal segmentation model was used to determine the boundary between juvenile and mature wood. The results showed that the variation of the early stage (before the 20th year) was larger than that of the later stage (after the 20th year); moreover, the variation of the vessel features (9.56%) was greater than that of the fiber features (7.42%), the vessel lumen diameter (11.94%) and the fiber length (8.00%) had the most variation. There were three radial variation patterns in the wood properties. In the early stage, there was a significant positive correlation between the ring width and wood air-dry density (0.78) and wood basic density (0.89), and a significant negative correlation between the ring width and the fiber characters (−0.79~−0.93) and vessel characters (−0.64~−0.90). The growth models of Logistic and Richards were more suitable (R2 = 84.2%~95.2%) for the radial variation of wood anatomical properties than the nonlinear least square model (R2 = 67.7%~90.9%). The transition wood between juvenile and mature wood of S. superba was from the 11th to the 16th year based on aggregative indicators from the pith to bark at breast height. Finally, when taken together, the wood anatomical properties of S. superba had regular radial variation. Breeding programs need to consider both growth and wood anatomical properties in the early stage, but they can be neglected in the mature stage. The formation of mature wood of S. superba occurred after the 16th year. Full article
(This article belongs to the Section Wood Science and Forest Products)
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16 pages, 6260 KiB  
Article
Resistance, Recovery and Resilience of Two Co-Occurring Palaeotropical Pinus Species Differing in the Sizes of Their Distribution Areas
by Le T. Ho, Jana Hoppe and Frank M. Thomas
Forests 2021, 12(4), 511; https://doi.org/10.3390/f12040511 - 20 Apr 2021
Cited by 2 | Viewed by 3033
Abstract
Using a dendrochronological approach, we determined the resistance, recovery and resilience of the radial stem increment towards episodes of growth decline, and the accompanying variation of 13C discrimination against atmospheric CO2 (Δ13C) in tree rings of two palaeotropical pine [...] Read more.
Using a dendrochronological approach, we determined the resistance, recovery and resilience of the radial stem increment towards episodes of growth decline, and the accompanying variation of 13C discrimination against atmospheric CO2 (Δ13C) in tree rings of two palaeotropical pine species. These species co-occur in the mountain ranges of south–central Vietnam (1500–1600 m a.s.l.), but differ largely in their areas of distribution (Pinus kesiya from northeast India to the Philippines; P. dalatensis only in south and central Vietnam and in some isolated populations in Laos). For P. dalatensis, a robust growth chronology covering the past 290 years could be set up for the first time in the study region. For P. kesiya, the 140-year chronology constructed was the longest that could be established to date in that region for this species. In the first 40 years of the trees’ lives, the stem diameter increment was significantly larger in P. kesiya, but levelled off and even decreased after 100 years, whereas P. dalatensis exhibited a continuous growth up to an age of almost 300 years. Tree-ring growth of P. kesiya was negatively related to temperature in the wet months and season of the current year and in October (humid transition period) of the preceding year and to precipitation in August (monsoon season), but positively to precipitation in December (dry season) of the current year. The P. dalatensis chronologies exhibited no significant correlation with temperature or precipitation. Negative correlations between BAI and Δ13C indicate a lack of growth impairment by drought in both species. Regression analyses revealed a lower resilience of P. dalatensis upon episodes of growth decline compared to P. kesiya, but, contrary to our hypothesis, mean values of the three sensitivity parameters did not differ significantly between these species. Nevertheless, the vigorous growth of P. kesiya, which does not fall behind that of P. dalatensis even at the margin of its distribution area under below-optimum edaphic conditions, is indicative of a relatively high plasticity of this species towards environmental factors compared to P. dalatensis, which, in tendency, is less resilient upon environmental stress even in the “core” region of its occurrence. Full article
(This article belongs to the Special Issue Modelling and Managing the Dynamics of Pine Forests)
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20 pages, 6704 KiB  
Article
Soil Physicochemical Properties and Fertility Evolution of Permanent Gully during Ecological Restoration in Granite Hilly Region of South China
by Juan Huang, Daihua Jiang, Yusong Deng, Shuwen Ding, Chongfa Cai and Zhigang Huang
Forests 2021, 12(4), 510; https://doi.org/10.3390/f12040510 - 20 Apr 2021
Cited by 12 | Viewed by 2794
Abstract
Permanent gullies are a serious type of soil erosion. A special type of permanent gully, called “Benggang” severly affects agricultural production in hilly areas. To reveal the influence of Benggang erosion on granitic soil restoration and fertility, we selected three stages (active, semi-stable [...] Read more.
Permanent gullies are a serious type of soil erosion. A special type of permanent gully, called “Benggang” severly affects agricultural production in hilly areas. To reveal the influence of Benggang erosion on granitic soil restoration and fertility, we selected three stages (active, semi-stable and stable) of Benggang recovery in the subtropical granite hilly region, and corresponding soil samples were collected to analyze the spatial variation in the soil physical and chemical qualities in the early stage of recovery. The soil physical properties and nutrients were significantly different in the runoff direction of each Benggang gully. There were significant differences in soil chemical properties and no obvious differences in physical properties among the different Benggang recovery stages. The results of principal component analysis showed that the level of soil fertility in the different Benggang recovery stages, ranked from high to low, was as follows: stable, semi-stable and active. Benggang vegetation restoration was an important factor for soil fertility restoration. Benggang ecological restoration can significantly improve the physicochemical properties and fertility of the soil. However, the soil fertility in gully erosion areas in this study still needs to be improved. Full article
(This article belongs to the Section Forest Ecology and Management)
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12 pages, 3081 KiB  
Review
Response of Temperate Forest Ecosystems under Decreased Nitrogen Deposition: Research Challenges and Opportunities
by Frank S. Gilliam
Forests 2021, 12(4), 509; https://doi.org/10.3390/f12040509 - 19 Apr 2021
Cited by 9 | Viewed by 2743
Abstract
Although past increases in emissions and atmospheric deposition of reactive nitrogen (Nr) provided the impetus for extensive research investigating the effects of excess N in terrestrial and aquatic ecosystems, the Clean Air Act and associated rules have led to decreases in [...] Read more.
Although past increases in emissions and atmospheric deposition of reactive nitrogen (Nr) provided the impetus for extensive research investigating the effects of excess N in terrestrial and aquatic ecosystems, the Clean Air Act and associated rules have led to decreases in emissions and deposition of oxidized N, especially in the eastern U.S., but also in other regions of the world. Thus, research in the near future must address the mechanisms and processes of recovery for impacted forests as they experience chronically less N in atmospheric depositions. Recently, a hysteretic model was proposed to predict this recovery. By definition, hysteresis is any phenomenon in which the state of a property depends on its history and lags behind changes in the effect causing it. Long-term whole-watershed additions of N at the Fernow Experimental Forest allow for tests of the ascending limb of the hysteretic model and provide an opportunity to assess the projected changes following cessation of these additions. A review of 10 studies published in the peer-reviewed literature indicate there was a lag time of 3–6 years before responses to N treatments became apparent. Consistent with the model, I predict significant lag times for recovery of this temperate hardwood ecosystem following decreases in N deposition. Full article
(This article belongs to the Special Issue Responses of Forest Ecosystems to Nitrogen Deposition)
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16 pages, 3944 KiB  
Article
Endogenous Transmission Mechanism and Spatial Effect of Forest Ecological Security in China
by Xiuting Cai, Bin Zhang and Jiehua Lyu
Forests 2021, 12(4), 508; https://doi.org/10.3390/f12040508 - 19 Apr 2021
Cited by 19 | Viewed by 2609
Abstract
Forest ecological security is an important component of ecological security and national security, and it is a requirement for the sustainable development of the forestry economy. In this study, based on the pressure–state–response (PSR) model, an evaluation index system of forest ecological security [...] Read more.
Forest ecological security is an important component of ecological security and national security, and it is a requirement for the sustainable development of the forestry economy. In this study, based on the pressure–state–response (PSR) model, an evaluation index system of forest ecological security was constructed regarding three aspects: the pressure on the forest ecosystem caused by human activities, the state of the forest ecosystem, and the response measures taken by humans to protect the forest ecosystem. The forest ecological security and its pressure, state, and response in 31 provinces (municipalities and autonomous regions) in China from 2004 to 2018 were evaluated. Furthermore, with the help of a mediating effect model, the Moran index, and a spatial econometric model, the interaction relationship, spatial correlation effect, and spatial spillover effect of the pressure–state–response of forest ecological security were analyzed. The results showed the following: First, during the study period, the forest ecological security of most provinces was at sensitive and critical safety levels, and the forest ecological security level in Northeast and Southwest China was generally higher than that in Northwest and East China. Second, regarding the pressure, state, and response of forest ecological security, the pressure was generally low but with an increasing trend, the state was relatively good with continuous improvement, and the response was clearly insufficient and showed a fluctuating downward trend. Third, there were six different transmission mechanisms between pressure, state, and response of forest ecological security, among which there were significant transmission barriers between pressure and response. Given these findings, we propose suggestions to promote the improvement of forest ecological security in China. Full article
(This article belongs to the Section Forest Economics, Policy, and Social Science)
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19 pages, 6332 KiB  
Article
Genome-Wide Characterization of Dirigent Proteins in Populus: Gene Expression Variation and Expression Pattern in Response to Marssonina brunnea and Phytohormones
by Lingling Li, Weibo Sun, Peijun Zhou, Hui Wei, Pu Wang, Hongyan Li, Shamsur Rehman, Dawei Li and Qiang Zhuge
Forests 2021, 12(4), 507; https://doi.org/10.3390/f12040507 - 19 Apr 2021
Cited by 15 | Viewed by 3470
Abstract
Marssonina brunnea causes a major disease that limits poplar growth. Lignin and lignan play essential roles in protecting plants from various biological stresses. Dirigent (DIR) proteins are thought to control the stereoselective coupling of coniferyl alcohol in the formation of lignan and lignin. [...] Read more.
Marssonina brunnea causes a major disease that limits poplar growth. Lignin and lignan play essential roles in protecting plants from various biological stresses. Dirigent (DIR) proteins are thought to control the stereoselective coupling of coniferyl alcohol in the formation of lignan and lignin. DIR family members have been well studied in several plant species, but no previous detailed genome-wide analysis has been carried out in forest trees, such as poplar. We identified 40 PtDIR genes in Populus trichocarpa and classified them into three subgroups (DIR-a, DIR-b/d, and DIR-e) based on phylogenetic analyses. These genes are distributed on 11 poplar chromosomes, and 80% of PtDIRs (32/40) are intronless. The cis-element analysis inferred that PtDIRs possess many types of biological and abiotic stress-response cis-elements. We also analyzed intra- and inter-specific collinearity, which provided deep insights into the evolutionary characteristics of the poplar DIR genes. Analyses of the protein tertiary structure and critical amino acid residues showed that PtDIR7–10 and PtDIR13–16, which belong to the DIR-a subfamily, might be involved in the regio- and stereo-selectivity of bimolecular phenoxy radical coupling in poplars. Quantitative reverse transcription polymerase chain reaction (RT-qPCR) analysis revealed different expression patterns for the PtDIR genes of P. trichocarpa and the PeDIR genes of ‘Nanlin 895’ in various tissues. Additionally, we analyzed responses of PeDIRs to M. brunnea and different phytohormone treatments (abscisic acid, salicylic acid, methyl jasmonate, and ethylene) in ‘Nanlin 895’. The results showed that at least 18 genes responded strongly to M. brunnea, and these PeDIRs also showed significant responses to phytohormones. These results suggest that DIR genes are involved in the poplar defense response against M. brunnea, and this study will provide fundamental insights for future research on poplar DIR genes. Full article
(This article belongs to the Section Genetics and Molecular Biology)
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14 pages, 8021 KiB  
Article
Cambial Activity and Phenology in Three Understory Species along an Altitude Gradient in Mexico
by Mayte S. Jiménez-Noriega, Lauro López-Mata and Teresa Terrazas
Forests 2021, 12(4), 506; https://doi.org/10.3390/f12040506 - 17 Apr 2021
Cited by 4 | Viewed by 2373
Abstract
The aims of this study were to evaluate the cambial activity and phenology of three species with different life forms (Alchemilla procumbens, Acaena elongata and Ribes ciliatum) along an altitudinal gradient and to establish which environmental variables (light, soil humidity [...] Read more.
The aims of this study were to evaluate the cambial activity and phenology of three species with different life forms (Alchemilla procumbens, Acaena elongata and Ribes ciliatum) along an altitudinal gradient and to establish which environmental variables (light, soil humidity and temperature) had the greatest influence on cambial activity and phenological stages. Over two years, data on phenology, growth and cambium were gathered every four weeks in three to six sites per species in Sierra Nevada, Mexico. The results showed that Ribes is the only species that terminates cambial activity with leaves senescence and is influenced by the minimum soil temperature. The light environment influenced the vegetative stages in Alchemilla (cryptophyte), while in Acaena (hemicryptophyte), the mean soil temperature explained the findings related to leaf area during the dry season and growth along the gradient. In the three species, the reproductive phase dominated for a longer period at higher elevations, especially in Alchemilla. Only Ribes, the phanerophyte, showed a similar cambial activity to other trees and shrubs. Although cambium reactivates during the dry season, no xylogenesis occurs. The three species varied during the time in which vascular cambium was active, and this was dependent on the altitude. Specifically, the variation was more rhythmic in Ribes and switched on and off in Alchemilla. It is likely that, depending on the life form, vascular cambium may be more or less susceptible to one or more climate factors. Full article
(This article belongs to the Section Forest Ecophysiology and Biology)
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19 pages, 2818 KiB  
Article
Niche Selection by Soil Bacterial Community of Disturbed Subalpine Forests in Western Sichuan
by Zheliang Sheng, Wanze Zhu, Huaiying Yao, Shumiao Shu, Xia Li, Shenglan Ma, Yaying Li and Jinbo Xiong
Forests 2021, 12(4), 505; https://doi.org/10.3390/f12040505 - 17 Apr 2021
Cited by 5 | Viewed by 2350
Abstract
Soil bacterial microbial communities are important in the ecosystem function and succession of forests. Using high-throughput 16S rRNA gene sequencing and relative importance for linear regression, we explored how the structures of soil bacterial community were influenced by the environmental factors and restoration [...] Read more.
Soil bacterial microbial communities are important in the ecosystem function and succession of forests. Using high-throughput 16S rRNA gene sequencing and relative importance for linear regression, we explored how the structures of soil bacterial community were influenced by the environmental factors and restoration succession of secondary forests in the Miyaluo Mountains of western Sichuan, China. Using a space-for-time approach, field measurements and sampling were conducted in four stands at different stages of natural restoration. Results of distance-based multivariate analysis showed that soil pH, organic carbon, available phosphorus, and C/N ratio were the predominant environmental factors that collectively explained a 46.9% variation in the bacterial community structures. The community compositions were jointly controlled by the direct and indirect effects of the rehabilitation stages. The changes in soil environmental factors coincided with restoration succession could lead to the shifts in the relative abundance of different soil bacterial taxa. We screened 13 successional discriminant taxa that could quantitatively indicate the secondary succession subalpine stage. Collectively, our findings show that soil bacteria in different taxa are governed by different local soil variables and rehabilitation ages, which can lead to shifts in the relative abundance of different taxa in successional stages, ultimately changing the entire soil bacterial community with the succession of secondary forest. Full article
(This article belongs to the Section Forest Ecology and Management)
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10 pages, 728 KiB  
Article
Using Direct and Indirect Methods to Assess Changes in Riparian Habitats
by Aleksandra Halarewicz, Daniel Pruchniewicz and Dorota Kawałko
Forests 2021, 12(4), 504; https://doi.org/10.3390/f12040504 - 17 Apr 2021
Cited by 3 | Viewed by 2268
Abstract
Hydrological regime disturbances in riparian ecosystems affect the interactions between soil properties and vegetation. The proper assessment of changes occurring in river valley forests is a basis for planning in sustainable forest management. The existing habitat conditions in plant communities can be assessed [...] Read more.
Hydrological regime disturbances in riparian ecosystems affect the interactions between soil properties and vegetation. The proper assessment of changes occurring in river valley forests is a basis for planning in sustainable forest management. The existing habitat conditions in plant communities can be assessed by both direct and indirect measurements. The aim of the study was to compare the results obtained with direct and indirect methods of data collection. We also evaluated the validity of the studied variables. Our study was based on data from plots established in 90-year-old forests in the Odra river valley (SW Poland). Habitat features, such as soil moisture (F), nitrogen (N), and soil reaction (R), were expressed directly using field measurements and indirectly using Ellenberg’s indicator values, calculated based on the presence/absence of species in a plot (aEIVs) as well as on species cover (wEIVs). Only in the case of nitrogen did the use of both methods of estimating habitat features give the same results for selected riverside forests. In ordination and regressive analyses, use of direct or indirect methods strongly influences the results of calculations. Analyses conducted on the basis of selected parameters indicate a significant decrease in soil moisture and a change in soil reaction in the riparian forest located on the edge of the floodplain, which indicates that the habitat transformation has already begun. We concluded that the use of Ellenberg’s indicator values (EIVs) for monitoring riparian habitats has numerous disadvantages, and therefore data based on direct measurement should be preferred. Full article
(This article belongs to the Special Issue Effects of Forest Management and Climate Change on Forest Vegetation)
14 pages, 1640 KiB  
Article
Competition Restricts the Growth, Development, and Propagation of Carpinus tientaiensis: A Rare and Endangered Species in China
by Liangjin Yao, Yuanke Xu, Bo Jiang, Chuping Wu, Weigao Yuan, Jinru Zhu, Tingting Li and Zhigao Wang
Forests 2021, 12(4), 503; https://doi.org/10.3390/f12040503 - 17 Apr 2021
Cited by 7 | Viewed by 2226
Abstract
The protection and propagation of rare and endangered species are key to the preservation of their population development; however, due to the scarcity of individuals, the potential effects and status of rare and endangered species in the whole forest ecosystem are still poorly [...] Read more.
The protection and propagation of rare and endangered species are key to the preservation of their population development; however, due to the scarcity of individuals, the potential effects and status of rare and endangered species in the whole forest ecosystem are still poorly understood. Using data from a 60 × 140 m forest dynamic monitoring sample of the Carpinus tientaiensis (Betulaceae) species in Zhejiang of Southeast China. We assessed the population distribution and diameter at breast height (DBH) structure of the Carpinus tientaiensis species, which was a rare and endangered species, as well as intra- and interspecific correlation with other species. The results show that saplings (1 cm ≤ DBH < 5 cm) and juveniles (5 cm ≤ DBH < 10 cm) were more aggregated than larger individuals (DBH ≥ 20 cm) of Carpinus tientaiensis. The DBH size structure of all the trees shows an obvious inverted “J” distribution. With an increase in the DBH size category, the number of individuals gradually decreases. Due to the diffusion limitation, the spatial distribution patterns of all the tree individuals and roof geese in the sample land are increased at a small spatial scale, and as the spatial scale increases, the degree of aggregation decreases gradually. The relationship between different diameter stages of the population of Carpinus tientaiensis showed a consistent general trend. The spatial distribution of individuals with a large diameter on a small scale was significantly positively correlated (p < 0.001). With an increase in the scale, there was no significant correlation (p > 0.05) between individuals with a large diameter and individuals with a small diameter. There was no significant correlation (p > 0.05) between the population of Carpinus tientaiensis and other species in the sample, and the strong unidirectional competition of other species in the sample can be seen by the competition index. We found that interspecific competition restricts the growth and expansion of Carpinus tientaiensis, and it has adopted different ecological strategies to coexist with a population of common tree species occupying a similar living space. Full article
(This article belongs to the Special Issue Patterns of Tree Species Diversity and Forest Structure)
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10 pages, 2048 KiB  
Communication
North-Westward Expansion of the Invasive Range of Emerald Ash Borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) towards the EU: From Moscow to Saint Petersburg
by Dmitry L. Musolin, Andrey V. Selikhovkin, Elena Y. Peregudova, Boris G. Popovichev, Michail Y. Mandelshtam, Yuri N. Baranchikov and Rimvys Vasaitis
Forests 2021, 12(4), 502; https://doi.org/10.3390/f12040502 - 16 Apr 2021
Cited by 16 | Viewed by 2855
Abstract
Agrilus planipennis is a devastating invasive pest of ash trees in European Russia, Ukraine, and North America. To monitor the north-western limit of its European invasive range, in June 2018 we established 10 study plots along the federal highway M10 (Russia) that runs [...] Read more.
Agrilus planipennis is a devastating invasive pest of ash trees in European Russia, Ukraine, and North America. To monitor the north-western limit of its European invasive range, in June 2018 we established 10 study plots along the federal highway M10 (Russia) that runs between Moscow and Saint Petersburg through Tver’ City (approx. 180 km from Moscow), and lined with ash trees. On each plot, 2–4 Fraxinus pennsylvanica trees with heights ranging 6.1–17.0 m and diameters ranging 7.0–18.0 cm were girdled, i.e., 50 cm of their bark were removed. The study plots were visited and girdled trees were examined in September and November, 2018, and in October, 2019. Observations revealed that the current continuous north-western limit of A. planipennis range in European Russia coincides with the north-western border of Tver’ City and this range limit has not distinctly shifted north-westward during 2015–2019. In spite of the rich food supply (due to abundant F. pennsylvanica and F. excelsior plantings) in Tver’ City and along roads going to and from, the population density of A. planipennis in the area is currently low. Recent (September 2020) sudden detection of a spatially isolated A. planipennis outbreak approx. 520 km far north-westward from Tver’ (in Saint Petersburg) suggested that A. planipennis most likely had arrived at Saint Petersburg not by gradual stepwise (flying tree-to-tree) expansion of its continuous invasive range in Tver’ City, but as a result of its accidental introduction by means of, e.g., “insect-hitchhiked” vehicles, transported plants for planting, and/or other commodities. The proximity of the reported A.planipennis outbreak to the borders of the EU (approx. 130 km to Estonia and Finland) requires urgent measures for its containment and control, and constant monitoring. Full article
(This article belongs to the Section Forest Ecology and Management)
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11 pages, 736 KiB  
Article
Influence of Abiotic and Biotic Factors on Soil Microbial Biomass in Robinia pseudoacacia Plantations in the Loess Hilly Region
by Wenyan Xue, Yunming Chen, Congguo Dong and Yuning Qiao
Forests 2021, 12(4), 501; https://doi.org/10.3390/f12040501 - 16 Apr 2021
Viewed by 2078
Abstract
The ecological productivity of the Robinia pseudoacacia L. (RP) widely cultivated on the Loess hilly region has been widely questioned with its aging. Soil microbial biomass (SMB) plays a key role in soil nutrient dynamics and productivity of the ecosystems. Understanding the main [...] Read more.
The ecological productivity of the Robinia pseudoacacia L. (RP) widely cultivated on the Loess hilly region has been widely questioned with its aging. Soil microbial biomass (SMB) plays a key role in soil nutrient dynamics and productivity of the ecosystems. Understanding the main ecological drivers of SMB is supposed to be of importance for ecosystem functioning of RP in the Loess hilly region. In this study, we identified the most influential factors affecting SMB at 2 layers (0–10 cm and 10–30 cm) using forward selection in terms of plant characteristics (forest age, tree height, diameter at breast height, tree canopy, crown base height, herb height, herb number, herb coverage, herb ground diameter and herb diversity), soil physiochemical characteristics (soil bulk density, pH, water content, soil organ carbon, soil total and available nutrient content) and topographical properties (elevation, aspect and slope). We also analyzed individual and interactive effects (plant–soil, plant–topography, soil–topography, plant–soil–topography) using general linear model (GLM) analysis. Among all plant variables, tree canopy and understory richness had the greatest impact on SMB. The soil variables with the greatest impact on SMB were bulk density and available phosphorus. Elevation was the most important topographic factor affecting SMB. When we considered the interactive effects among plant, soil physicochemical and topographical variables on SMB, a significant interaction effect occurred at a depth of 10–30 cm soil layer. We concluded that individual effects of abiotic and biotic factors significantly affect SMB at 0–10 cm, while the interaction of these factors mainly played roles at 10–30 cm. These results provide a basis for maintaining soil health and productivity using efficient SMB by providing suitable abiotic and biotic habitats. Full article
(This article belongs to the Section Forest Ecology and Management)
13 pages, 1805 KiB  
Article
Influence of Slope Direction on the Soil Seed Bank and Seedling Regeneration of Castanopsis hystrix Seed Rain
by Zong Zhao, Yong Liu, Hongyan Jia, Wensheng Sun, Angang Ming, Shengjiang Pang, Ning An, Jihui Zhang, Chuang Tang and Shitao Dong
Forests 2021, 12(4), 500; https://doi.org/10.3390/f12040500 - 16 Apr 2021
Cited by 7 | Viewed by 2481
Abstract
Objective: To investigate the impact of different slope directions on the quantity and quality of the soil seed bank and seedling germination process of Castanopsis hystrix plantations. Method: Fixed sample plots in forest stands of Castanopsis hystrix were established on different slope directions [...] Read more.
Objective: To investigate the impact of different slope directions on the quantity and quality of the soil seed bank and seedling germination process of Castanopsis hystrix plantations. Method: Fixed sample plots in forest stands of Castanopsis hystrix were established on different slope directions (sunny slope, semi-sunny slope, semi-shady slope, and shady slope). The characteristics of the forest stand were investigated, and per-wood scaling was carried out. The temporal dynamics of the seed rain and seed bank were quantified using seed rain collectors and by collecting soil samples from different depths. The quantity and quality of the seeds were determined, and the vigor of mature seeds was measured throughout the study. Results: (1) The diffusion of Castanopsis hystrix seed rain started in mid-September, reached its peak from late October to early November, and ended in mid-December. (2) The dissemination process, occurrence time, and composition of the seed rain varied between the different slope directions. The seed rain intensity on the semi-sunny slope was the highest (572.75 ± 9.50 grains∙m−2), followed by the sunny slope (515.60 ± 10.28 grains∙m−2), the semi-shady slope (382.13 ± 12.11 grains∙m−2), and finally the shady slope (208.00 ± 11.35 grains∙m−2). The seed rain on the sunny slope diffused earliest and lasted the longest, while the seed rain on the shady slope diffused latest and lasted the shortest time. Seed vigor and the proportion of mature seeds within the seed rain were greatest on the semi-sunny slope, followed by the sunny slope, semi-shady slope, and the shady slope. (3) From the end of the seed rain to August of the following year, the amount of total reserves of the soil seed banks was highest on the semi-sunny slope, followed by the sunny slope then the semi-shady slope, and it was the lowest on the shady slope. The amount of mature, immature, gnawed seeds and seed vigor of the soil seed bank in various slope directions showed a decreasing trend with time. The seeds of the seed bank in all slope directions were mainly distributed in the litter layer, followed by the 0–2 cm humus layer, and only a few seeds were present in the 2–5 cm soil layer. (4) The seedling density of Castanopsis hystrix differed significantly on the different slope directions. The semi-sunny slope had the most seedlings, followed by the sunny slope, semi-shady slope, and the shady slope. Conclusions: The environmental conditions of the semi-sunny slope were found to be most suitable for the seed germination and seedling growth of Castanopsis hystrix, and more conducive to the regeneration and restoration of its population. Full article
(This article belongs to the Section Forest Ecology and Management)
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15 pages, 8518 KiB  
Article
Mapping and Monitoring the Canopy Cover and Greenness of Southern Yellow Pines (Loblolly, Shortleaf, and Virginia Pines) in Central-Eastern Tennessee Using Multi-Temporal Landsat Satellite Data
by Clement Akumu, Raphael Smith and Solomon Haile
Forests 2021, 12(4), 499; https://doi.org/10.3390/f12040499 - 16 Apr 2021
Cited by 1 | Viewed by 2251
Abstract
Southern yellow pines such as loblolly, Virginia and shortleaf pines constitute forest products and contribute significantly to the economy of the United States (U.S.). However, little is understood about the temporal change in canopy cover and greenness of southern yellow pines, especially in [...] Read more.
Southern yellow pines such as loblolly, Virginia and shortleaf pines constitute forest products and contribute significantly to the economy of the United States (U.S.). However, little is understood about the temporal change in canopy cover and greenness of southern yellow pines, especially in Tennessee where they are used for timber and pulpwood. This study aims to map and monitor the canopy cover and greenness of southern yellow pines i.e., loblolly (Pinus taeda), shortleaf (Pinus echinata), and Virginia (Pinus Virginiana) pines in the years 1988, 1999 and 2016 in central-eastern Tennessee. Landsat time-series satellite data acquired in December 1988, November 1999 and February 2016 were used to map and monitor the canopy cover and greenness of loblolly, shortleaf and Virginia pines. The classification and mapping of the canopy cover of southern yellow pines were performed using a machine-learning random forest classification algorithm. Normalized Difference Vegetation Index (NDVI) was used to monitor the temporal variation in canopy greenness. In total, the canopy cover of southern yellow pines decreased by about 35% between December 1988 and February 2016. This information could be used by foresters and forest managers to support forest inventory and management. Full article
(This article belongs to the Special Issue Applications of Satellite Data for Forest Monitoring and Management)
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15 pages, 2976 KiB  
Article
The Impact of Drought Stress on the Height Growth of Young Norway Spruce Full-Sib and Half-Sib Clonal Trials in Sweden and Finland
by Haleh Hayatgheibi, Matti Haapanen, Jenny Lundströmer, Mats Berlin, Katri Kärkkäinen and Andreas Helmersson
Forests 2021, 12(4), 498; https://doi.org/10.3390/f12040498 - 16 Apr 2021
Cited by 12 | Viewed by 3380
Abstract
The summer drought of 2018 was one of the most climatically severe events in Europe that led to record-breaking temperatures and wildfires in many parts of Europe. The main objective of this study was to assess the impact of the 2018 drought on [...] Read more.
The summer drought of 2018 was one of the most climatically severe events in Europe that led to record-breaking temperatures and wildfires in many parts of Europe. The main objective of this study was to assess the impact of the 2018 drought on the phenotypic and genetic response of Norway spruce height growth using the Standardized Precipitation-Evapotranspiration Index (SPEI). To achieve this, the total cumulative height growth of about 6000 clones from 2016 to 2019 in four full-sib trials in Sweden, aged 6–7 years, and from 2017 to 2019 in two half-sib trials in Finland, aged 8–9 years, were measured. The results indicate that the 2018 drought caused reductions in the increment of trees. Although heritability estimates were similar to other reports for Norway spruce, the additive genetic variance was highly inflated in one of the visibly drought-damaged trials in Southern Sweden. Similarly, the genotype by environment (G × E) interaction was highly significant in the drought-damaged Southern Swedish trials. Both additive genetic and phenotypic correlations obtained between height increments in 2019 and final heights were the weakest in all studied trials, implying that the drought legacies might have influenced the recovery of trees in 2019. We may conclude that the severe drought can be an underlying factor for a strong G × E interaction and changes in the ranking of genotypes. Therefore, a selection of drought-resistant genotypes with a good growth capacity tested in variables sites should be considered as an important criterion for future breeding of Norway spruce. Full article
(This article belongs to the Section Genetics and Molecular Biology)
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23 pages, 13886 KiB  
Article
Comparing Strengths and Weaknesses of Three Approaches in Estimating Social Demands for Local Forest Ecosystem Services in South Korea
by Jang-Hwan Jo, Moongi Choi, Chang-Bae Lee, Kyeong-hak Lee and Oh Seok Kim
Forests 2021, 12(4), 497; https://doi.org/10.3390/f12040497 - 16 Apr 2021
Cited by 4 | Viewed by 2672
Abstract
This study is aimed to compare the strengths and weaknesses of three approaches—analytic hierarchy process analysis, sentiment analysis, and floating population analysis—in estimating the social demands for local forest ecosystem services (ES) in South Korea: Gariwangsan and Yeoninsan. The results were as follows: [...] Read more.
This study is aimed to compare the strengths and weaknesses of three approaches—analytic hierarchy process analysis, sentiment analysis, and floating population analysis—in estimating the social demands for local forest ecosystem services (ES) in South Korea: Gariwangsan and Yeoninsan. The results were as follows: First, the survey respondents of Gariwangsan and Yeoninsan believed that the cultural ES category was the most fundamental one that should be maintained, whereas they thought the supporting ES category needed the least maintenance. Second, both forests had a high frequency of sentiment words related to the cultural ES category, followed by the regulating ES category, such as air and water quality improvement. Third, the spatiotemporal distribution of the floating populations in both forests was concentrated in their valleys and mountainous areas, indicating the finer-scale demands for the cultural and regulating ES category. Fourth, the research shows the areas that are high in demand and those that are not; this result helps forest management. In conclusion, none of the three methodologies was superior to the other two, as they each captured distinct ES demands. To investigate ES demands in a multifaceted way, we suggest applying the three approaches in tandem. Full article
(This article belongs to the Section Forest Economics, Policy, and Social Science)
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18 pages, 4041 KiB  
Article
Soil Respiration in Alder Swamp (Alnus glutinosa) in Southern Taiga of European Russia Depending on Microrelief
by Tamara V. Glukhova, Danil V. Ilyasov, Stanislav E. Vompersky, Alla V. Golovchenko, Natalia A. Manucharova and Alexey L. Stepanov
Forests 2021, 12(4), 496; https://doi.org/10.3390/f12040496 - 16 Apr 2021
Cited by 12 | Viewed by 2699
Abstract
Swamp forests have been insufficiently studied yet in comparison with thoroughly examined carbon pools and greenhouse gas fluxes of peat bogs. This is primarily since the GHGs in swamp forests have huge spatial (due to the developed microrelief) and temporal variations (due to [...] Read more.
Swamp forests have been insufficiently studied yet in comparison with thoroughly examined carbon pools and greenhouse gas fluxes of peat bogs. This is primarily since the GHGs in swamp forests have huge spatial (due to the developed microrelief) and temporal variations (due to strong fluctuations in the groundwater level (GWL)). This significantly complicates their study, producing ambiguous results, especially in short-term field research. From June to October 2013–2016, we measured soil respiration (Rsoil) in an alder swamp using the static chamber method at five microsites: depression (DEP), flat surface (FL), elevations (EL), tussocks (TUS), and near-stem tussocks (STUS). We carried out a computer simulation of the total Rsoil for the season based on Rsoil measurements, monitoring of GWL, and soil temperature. In 2013–2016, the average Rsoil values (mgC m−2 h−1 ± σ) on DEP, FL, EL, TUS and STUS comprised 54 ± 50, 94 ± 72, 146 ± 89, 193 ± 96, and 326 ± 183, respectively, whereas the total Rsoil values for the season (tC ha−1 season−1 ± σ) comprised 2.0 ± 0.5, 3.5 ± 0.5, 5.3 ± 1.6, 5.4 ± 2.7, and 12.6 ± 3.2. According to the results of observations, GWL was at the level of several cm below the soil surface for most of the season. In 2014 and 2015, there were extra dry periods that led to a drop in GWL to a mark of 30–40 cm below the soil surface. Despite their short duration (2–3 weeks), these dry periods can lead to an increase in the total Rsoil for the season from 9 to 45% in the TUS–EL–STUS–FL–DEP sequence. Full article
(This article belongs to the Special Issue Forest Soil Carbon and Climate Changes)
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11 pages, 1915 KiB  
Article
Gypsy Moth Management with LdMNPV Baculovirus in Cork Oak Forest
by Luca Ruiu, Roberto Mannu, Maurizio Olivieri and Andrea Lentini
Forests 2021, 12(4), 495; https://doi.org/10.3390/f12040495 - 16 Apr 2021
Cited by 8 | Viewed by 2767
Abstract
(1) Research Highlights: Applications of a species-specific baculovirus is a promising method to control the gypsy moth and regulate its population dynamics in forest ecosystems. (2) Background and Objectives: Cork oak protection against the Lepidopteran defoliator Lymantria dispar requires an appropriate forest ecosystem [...] Read more.
(1) Research Highlights: Applications of a species-specific baculovirus is a promising method to control the gypsy moth and regulate its population dynamics in forest ecosystems. (2) Background and Objectives: Cork oak protection against the Lepidopteran defoliator Lymantria dispar requires an appropriate forest ecosystem management program, involving the application of eco-sustainable microbial products during population outbreaks. The species-specific multicapsid nucleopolyhedrovirus (LdMNPV), agent of natural epizootics in gypsy moth populations, represents an option that was investigated in a multi-year field study, involving viral applications either from the ground or by aerial treatment. (3) Materials and Methods: Efficacy trials against L. dispar populations were conducted in 2018 and 2019 in Sardinia, according to a randomized block design. Each year, two trials were conducted, applying a baculovirus commercial formulation with an atomizer from the ground and assessing the effects of different doses and application timing, respectively. An aerial application trial distributing LdMNPV at ultra-low volumes (2 L/ha) was also conducted in 2019 to assess the virus efficacy at a larger field scale. (4) Results: In both years, a significant increase in larval mortality was detected in plots treated with higher viral occlusion body (OB) doses and with an earlier application targeting younger larvae, in comparison with untreated controls. Due to an observed retrogradation phase of the target pest in 2019, no significant differences in larval density between areas treated from a helicopter and control were detected, but in the few weeks following application, a meaningful vitality decrease in larval samples from treated plots was observed. (5) Conclusions: Based on the results of this study, the use of LdMNPV in forest protection programs against gypsy moth can be worth consideration in multi-year integrated program strategies to modulate population dynamics. Full article
(This article belongs to the Special Issue Forest Pathology and Entomology)
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22 pages, 3460 KiB  
Article
Wood Anatomical Traits Reveal Different Structure of Peat Bog and Lowland Populations of Pinus sylvestris L. in the Carpathian Region
by Balázs Palla, Márta Ladányi, Klára Cseke, Krisztina Buczkó and Mária Höhn
Forests 2021, 12(4), 494; https://doi.org/10.3390/f12040494 - 16 Apr 2021
Cited by 5 | Viewed by 2659
Abstract
Ecologically extreme habitats at a species’ distribution edges bear significance for biota under adverse climatic conditions and climate change. Range-edge populations adjust their functional traits to the special local ecological conditions, leading to increased intraspecific variability in their morpho-anatomical structure and, consequently, favor [...] Read more.
Ecologically extreme habitats at a species’ distribution edges bear significance for biota under adverse climatic conditions and climate change. Range-edge populations adjust their functional traits to the special local ecological conditions, leading to increased intraspecific variability in their morpho-anatomical structure and, consequently, favor population survival in the absence of competitors. On the basis of wood anatomical traits, such as tracheid lumen area (CA), cell wall thickness (CWTrad), cell diameter-to-radial cell wall thickness ratio (CD/CWT), and the number of tracheids in the radial tracheid files (TNo), we investigated the xylem adjustment of Pinus sylvestris L. populations from six ecologically extreme habitats from the Eastern Carpathians and the Pannonian Basin. Results indicated significant differences among all studied sites in case of all wood anatomical traits as signs of the local adaptation of trees. Peat bog populations adapted their wood anatomical traits to the generally hydric, cool and anaerobic conditions of the peat bogs, exhibiting smaller CA and proportionally thick CWTrad to ensure the hydraulic safety of the stem, whereas, on the lowland site, trees were characterized by a more effective water-conducting system, developing larger CA with relatively thin CWTrad with lower carbon-per-conduit-costs at the expense of higher vulnerability to cavitation. Radial tree ring growth and TNo also differed markedly among sites, following the temperature and groundwater constraints of the habitats. Wood anatomical variability among tree rings and the corresponding short-term climate response of populations differed from the adaptive responses of the trees to the ecological characteristics of the habitat. In addition to the different phylogeographic origin evidenced in former studies, phenotypic differentiation by the habitat type of the studied populations linked to the variance in morpho-anatomical traits have contributed to the survival of the peripheral Scots pine populations at the species’ range margins. Full article
(This article belongs to the Special Issue Genetic Resources and Adaptive Management of Conifers in a Changing World)
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18 pages, 2111 KiB  
Article
Adoption of Agroforestry in Northwest Viet Nam: What Roles Do Social and Cultural Norms Play?
by Mai Phuong Nguyen, Tim Pagella, Delia C. Catacutan, Tan Quang Nguyen and Fergus Sinclair
Forests 2021, 12(4), 493; https://doi.org/10.3390/f12040493 - 16 Apr 2021
Cited by 9 | Viewed by 4650
Abstract
This article presents research about the influences of social and cultural norms on the adoption of agroforestry in the northwest mountainous region of Viet Nam. The farming systems practiced by various ethnic groups in the northwest mainly occur on sloping land, which extends [...] Read more.
This article presents research about the influences of social and cultural norms on the adoption of agroforestry in the northwest mountainous region of Viet Nam. The farming systems practiced by various ethnic groups in the northwest mainly occur on sloping land, which extends over 70% of the land area in the region. Decades of intensive monoculture of annual crops has resulted in severe soil erosion, contributing to soil degradation and decline in crop yields. Integrating agroforestry practices on sloping land has the potential to halt and reverse soil degradation and improve local livelihoods, but its adoption is conditioned by the diverse social and cultural norms of different ethnic groups. This research applies knowledge-based system methods in order to understand local opportunities, preferences, and constraints influencing the adoption of agroforestry practices, using a purposive, gender-balanced sample of sixty farmers from six villages across three provinces in the northwest region comprising people from Kinh, Thai and H’mong ethnic groups. Our results show that although farmers from all groups are aware of the economic and ecological benefits of trees for soil conservation in general, they have different perceptions about the benefits of particular agroforestry practices. Behavioural norms controlling agroforestry adoption vary amongst ethnic groups, and farmers’ individual social and cultural preferences influence their aspirations and adoption decisions. We conclude that developing appropriate agricultural interventions in a culturally rich environment such as northwest Viet Nam requires understanding of the context-specific needs and interests of socially and culturally disaggregated populations. Policies supporting agroforestry are more likely to contribute to more sustainable livelihoods and ecological benefits where they are tailored to the requirements of different ethnic groups. Full article
(This article belongs to the Special Issue Systematic Approach to Agroforestry Policies and Practices in Asia)
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12 pages, 3264 KiB  
Review
Use of Ground Penetrating Radar in the Evaluation of Wood Structures: A Review
by Brunela Pollastrelli Rodrigues, Christopher Adam Senalik, Xi Wu and James Wacker
Forests 2021, 12(4), 492; https://doi.org/10.3390/f12040492 - 16 Apr 2021
Cited by 17 | Viewed by 4438
Abstract
This paper is a review of published studies involving the use of ground penetrating radar (GPR) on wood structures. It also contains background information to help the reader understand how GPR functions. The use of GPR on wood structures began to grow in [...] Read more.
This paper is a review of published studies involving the use of ground penetrating radar (GPR) on wood structures. It also contains background information to help the reader understand how GPR functions. The use of GPR on wood structures began to grow in popularity at the turn of the millennium. GPR has many characteristics that make it attractive as an inspection tool for wood: it is faster than many acoustic and stress wave techniques; it does not require the use of a couplant; while it can also detect the presence of moisture. Moisture detection is of prime concern, and several researchers have labored to measure internal moisture using GPR. While there have been several laboratory studies involving the use of GPR on wood, its use as an inspection tool on large wood structures has been limited. This review identified knowledge gaps that need to be addressed to improve the efficacy of GPR as a reliable inspection tool of wood structure. Chief among these gaps, is the ability to distinguish the type of internal feature from the GPR output and the ability to identify internal decay. Full article
(This article belongs to the Special Issue Nondestructive Evaluation of Forest Biomaterials: A Global Perspective)
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15 pages, 1436 KiB  
Article
Salicylic Acid-Induced Morpho-Physiological and Biochemical Changes Triggered Water Deficit Tolerance in Syzygium cumini L. Saplings
by Zikria Zafar, Fahad Rasheed, Rana Muhammad Atif, Muhammad Maqsood and Oliver Gailing
Forests 2021, 12(4), 491; https://doi.org/10.3390/f12040491 - 16 Apr 2021
Cited by 13 | Viewed by 3216
Abstract
Fruit tree culture is at the brink of disaster in arid to semi-arid regions due to low water availability. A pot experiment was carried out to analyze whether foliar application of salicylic acid (SA) can improve water stress tolerance in Syzygiumcumini. [...] Read more.
Fruit tree culture is at the brink of disaster in arid to semi-arid regions due to low water availability. A pot experiment was carried out to analyze whether foliar application of salicylic acid (SA) can improve water stress tolerance in Syzygiumcumini. Saplings were subjected to control (CK, 90% of field capacity, FC), medium stress (MS, 60% of FC) and high stress (HS, 30% of FC) along with foliar application of 0.5 and 1.0 mM of SA. Results showed that soil water deficit significantly decreased leaf, stem and total dry weight, leaf gas exchange attributes and chlorophyll a, b. However, root dry weight and root/shoot ratio increased under MS and HS, respectively. Contrarily, foliar application of SA significantly improved chlorophyll a, b, leaf gas exchange attributes, and dry weight production under soil water deficit. Concentration of oxidants like hydrogen peroxide and superoxide radicals, along with malondialdehyde and electrolyte leakage increased under soil water deficit; however, decreased in plants sprayed with SA due to the increase in the concentration of antioxidant enzymes like superoxide dismutase, peroxidase, catalase and ascorbate peroxidase. Results suggest that the foliar application of SA can help improve water stress tolerance in Syzygiumcumini saplings; however, validation of the results under field conditions is necessary. Full article
(This article belongs to the Section Forest Ecophysiology and Biology)
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15 pages, 3026 KiB  
Article
Effects of Vegetation Type on Soil Shear Strength in Fengyang Mountain Nature Reserve, China
by Xin Liu, Xuefei Cheng, Nan Wang, Miaojing Meng, Zhaohui Jia, Jinping Wang, Shilin Ma, Yingzhou Tang, Chong Li, Lu Zhai, Bo Zhang and Jinchi Zhang
Forests 2021, 12(4), 490; https://doi.org/10.3390/f12040490 - 16 Apr 2021
Cited by 14 | Viewed by 2884
Abstract
Shear strength is an important mechanical property of soil, as its mechanical function plays critical roles in reducing land degradation and preventing soil erosion. However, shear strength may be affected by vegetation type through changes in the soil and root patterns. To understand [...] Read more.
Shear strength is an important mechanical property of soil, as its mechanical function plays critical roles in reducing land degradation and preventing soil erosion. However, shear strength may be affected by vegetation type through changes in the soil and root patterns. To understand the influences of different types of vegetation on shear strength, the soil shear indices of three typical vegetation types (broad-leaved forest, coniferous broad-leaved mixed forest, and grassland) were studied and evaluated at the Fengyang Mountain Nature Reserve, China. We employed a direct shear apparatus to measure the soil shear resistance index. We quantified the soil porosity, moisture content, and composition of particle size to determine the properties of the soil, and a root scanner was used to quantify the root index. The results revealed that there were significant differences in shear resistance indices at the stand level. Between the three vegetation types, the internal friction angle of the broad-leaved forest was the largest and the cohesion was the smallest. The soil moisture content and porosity of the coniferous broad-leaved mixed forest were higher than those of the broad-leaved forest, and the root volume density (RVD/cm3) of the broad-leaved forest was higher than that of the coniferous and broad-leaved mixed forest and grassland. Structural equation modeling results show that the soil particle size and root characteristics indirectly impacted the soil water content by affecting porosity, which finally affected shear strength. In general, there were significant differences in soil properties and plant root indices between the different stands, which had an impact on soil shear strength. Full article
(This article belongs to the Section Forest Ecology and Management)
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16 pages, 2392 KiB  
Article
Molecular Signatures of Reticulate Evolution within the Complex of European Pine Taxa
by Bartosz Łabiszak and Witold Wachowiak
Forests 2021, 12(4), 489; https://doi.org/10.3390/f12040489 - 15 Apr 2021
Cited by 4 | Viewed by 2782
Abstract
Speciation mechanisms, including the role of interspecific gene flow and introgression in the emergence of new species, are the major focus of evolutionary studies. Inference of taxonomic relationship between closely related species may be challenged by past hybridization events, but at the same [...] Read more.
Speciation mechanisms, including the role of interspecific gene flow and introgression in the emergence of new species, are the major focus of evolutionary studies. Inference of taxonomic relationship between closely related species may be challenged by past hybridization events, but at the same time, it may provide new knowledge about mechanisms responsible for the maintenance of species integrity despite interspecific gene flow. Here, using nucleotide sequence variation and utilizing a coalescent modeling framework, we tested the role of hybridization and introgression in the evolutionary history of closely related pine taxa from the Pinus mugo complex and P. sylvestris. We compared the patterns of polymorphism and divergence between taxa and found a great overlap of neutral variation within the P. mugo complex. Our phylogeny reconstruction indicated multiple instances of reticulation events in the past, suggesting an important role of interspecific gene flow in the species divergence. The best-fitting model revealed P. mugo and P. uncinata as sister species with basal P. uliginosa and asymmetric migration between all investigated species after their divergence. The magnitude of interspecies gene flow differed greatly, and it was consistently stronger from representatives of P. mugo complex to P. sylvestris than in the opposite direction. The results indicate the prominent role of reticulation evolution in those forest trees and provide a genetic framework to study species integrity maintained by selection and local adaptation. Full article
(This article belongs to the Section Genetics and Molecular Biology)
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4 pages, 657 KiB  
Editorial
Protected Areas in Forest Conservation: Challenges and Opportunities
by Panayiotis G. Dimitrakopoulos and Nikoleta Jones
Forests 2021, 12(4), 488; https://doi.org/10.3390/f12040488 - 15 Apr 2021
Cited by 1 | Viewed by 3604
Abstract
Forest ecosystems are important habitats for a vast number of species worldwide [...] Full article
(This article belongs to the Special Issue Protected Areas in Forest Conservation: Challenges and Opportunities)
13 pages, 1926 KiB  
Article
Enhancing the Resilience of a Mediterranean Forest to Extreme Drought Events and Climate Change: Pinus—Tetraclinis Forests in Europe
by Juan Miguel Moya-Pérez, María Francisca Carreño and Miguel Ángel Esteve-Selma
Forests 2021, 12(4), 487; https://doi.org/10.3390/f12040487 - 15 Apr 2021
Cited by 1 | Viewed by 2411
Abstract
The southeast Iberian Peninsula is the only place in the European Community where Tetraclinis articulata (Vahl) Masters populations are native. In this area, the optimal ecological niche for this species is occupied by Pinus halepensis (Miller). The increasing intensity of extreme drought events [...] Read more.
The southeast Iberian Peninsula is the only place in the European Community where Tetraclinis articulata (Vahl) Masters populations are native. In this area, the optimal ecological niche for this species is occupied by Pinus halepensis (Miller). The increasing intensity of extreme drought events induced by climate change causes severe declines in pine forests, while providing expansion opportunities for established Tetraclinis populations. Within the framework of the LIFE-TETRACLINIS project, a study has been designed to simulate the pine forest decline effects on the population dynamics of this protected species. This work investigates the effects of decreasing competition on T. articulata specimens with limited reproductive activity. To induce the reproductive activity of these specimens through increasing the availability of light, the surrounding pines were removed within a 15 m radius. Increased light availability was modelled using “Light Detection And Ranging” (LiDAR) data, and changes in the main reproductive parameters were registered throughout the study period. A significant increase in the reproductive population was achieved, as well as the cones produced per specimen and the recruitment. Findings obtained are promising for the habitat management in continental Europe and enhancing this forest system’s resilience to extreme drought events and climate change. Full article
(This article belongs to the Special Issue Restoring Forest Landscapes: Impact on Soil Properties and Functions)
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22 pages, 5016 KiB  
Article
Useful Life of Prescribed Fires in a Southern Mediterranean Basin: An Application to Pinus pinaster Stands in the Sierra Morena Range
by Juan Ramón Molina, Macarena Ortega and Francisco Rodríguez y Silva
Forests 2021, 12(4), 486; https://doi.org/10.3390/f12040486 - 15 Apr 2021
Cited by 5 | Viewed by 2917
Abstract
Prescribed fire is a globally relevant fuel treatment for surface fuel management and wildfire hazard reduction. However, Mediterranean ecosystems are adapted to low and moderate fires; hence, the useful life of prescribed fires is limited. Useful life is defined as the effective rotation [...] Read more.
Prescribed fire is a globally relevant fuel treatment for surface fuel management and wildfire hazard reduction. However, Mediterranean ecosystems are adapted to low and moderate fires; hence, the useful life of prescribed fires is limited. Useful life is defined as the effective rotation length of prescribed fires to mitigate fire spread based on critical surface intensity for crown combustion. In this sense, the useful life of a prescribed fire focuses on surface fuel dynamics and its potential fire behavior. In Pinus pinaster stands, the useful life can be established between 0 and 4 years. Canopy base height, time elapsed from the burning, postfire precipitation, and fine fuel moisture content during the burning were identified as the most important variables in postburn fuel dynamics. Other stand characteristics and postfire precipitation can improve the fine fuel and live fuel dynamics models. Our findings support prescribed fires as an effective fuel treatment in the medium term for forest fire prevention, according to stand characteristics and burning implementation conditions. In this sense, forest managers can use the proposed decision tree to identify the useful life of each prescribed fire based on fine fuel moisture content during burning implementation. Full article
(This article belongs to the Special Issue Effects of Repeated Prescribed Fires on the Structure, Composition and Regeneration of Forests)
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23 pages, 8062 KiB  
Article
Composition and Specialization of the Lichen Functional Traits in a Primeval Forest—Does Ecosystem Organization Level Matter?
by Anna Łubek, Martin Kukwa, Bogdan Jaroszewicz and Patryk Czortek
Forests 2021, 12(4), 485; https://doi.org/10.3390/f12040485 - 15 Apr 2021
Cited by 2 | Viewed by 3091
Abstract
Current trends emphasize the importance of the examination of the functional composition of lichens, which may provide information on the species realized niche diversity and community assembly processes, thus enabling one to understand the specific adaptations of lichens and their interaction with the [...] Read more.
Current trends emphasize the importance of the examination of the functional composition of lichens, which may provide information on the species realized niche diversity and community assembly processes, thus enabling one to understand the specific adaptations of lichens and their interaction with the environment. We analyzed the distribution and specialization of diverse morphological, anatomical and chemical (lichen secondary metabolites) traits in lichen communities in a close-to-natural forest of lowland Europe. We considered these traits in relation to three levels of forest ecosystem organization: forest communities, phorophyte species and substrates, in order to recognize the specialization of functional traits to different levels of the forest complexity. Traits related to the sexual reproduction of mycobionts (i.e., ascomata types: lecanoroid apothecia, lecideoid apothecia, arthonioid apothecia, lirellate apothecia, stalked apothecia and perithecia) and asexual reproduction of mycobionts (pycnidia, hyphophores and sporodochia) demonstrated the highest specialization to type of substrate, tree species and forest community. Thallus type (foliose, fruticose, crustose and leprose thalli), ascospore dark pigmentation and asexual reproduction by lichenized diaspores (soredia and isidia) revealed the lowest specialization to tree species and substrate, as well as to forest community. Results indicate that lichen functional trait assemblage distribution should not only be considered at the level of differences in the internal structure of the analyzed forest communities (e.g., higher number of diverse substrates or tree species) but also studied in relation to specific habitat conditions (insolation, moisture, temperature, eutrophication) that are characteristic of a particular forest community. Our work contributes to the understanding of the role of the forest structure in shaping lichen functional trait composition, as well as enhancing our knowledge on community assembly rules of lichen species. Full article
(This article belongs to the Section Forest Ecology and Management)
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Article
Achieving Robust and Socially Acceptable Environmental Policy Recommendations: Lessons from Combining the Choice Experiment Method and Institutional Analysis Focused on Cultural Ecosystem Services
by Jiří Louda, Ondřej Vojáček and Lenka Slavíková
Forests 2021, 12(4), 484; https://doi.org/10.3390/f12040484 - 14 Apr 2021
Cited by 7 | Viewed by 2786
Abstract
The reflection of ecosystem services in environmental policy has recently become a key aspect in solving environmental problems occurring as a consequence of their overburdening. However, decision makers often pay attention predominantly to results of quantitative (monetary valuation) methods. This article explores a [...] Read more.
The reflection of ecosystem services in environmental policy has recently become a key aspect in solving environmental problems occurring as a consequence of their overburdening. However, decision makers often pay attention predominantly to results of quantitative (monetary valuation) methods. This article explores a new way of combining quantitative and qualitative methods that has proven to be a useful practice for achieving better environmental governance. We combine the (quantitative) choice experiment method and (qualitative) institutional analysis as full and equal complements. In our approach, the goal of qualitative institutional analysis is not to verify the adequacy of willingness-to-pay results but rather to better address cultural and social perspectives of society representatives. Such an approach increases the robustness of policy recommendations and their acceptance in comparison with isolated applications of both methods. To verify this general premise, both methods were applied in the territory of the Eastern Ore Mountains in the Czech Republic to capture preferences and attitudes of local stakeholders as well as tourists towards small-scale ecosystems. The results confirm that preference calculations regarding aesthetic values of ecosystems need to be complemented with facts about institutional settings and barriers in order to better address locally relevant recommendations for decision makers, such as the introduction of new economic instruments (e.g., local taxes or entrance fees). The findings of this study can also be considered for governance of larger local, common-pool resources such as (public) forests or protected areas. Full article
(This article belongs to the Special Issue The Economics of Forest Ecosystem Services and Biodiversity)
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