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Forests, Volume 9, Issue 2 (February 2018)

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Cover Story (view full-size image) Norway Spruce and European Larch = Hosts of Pine Pitch Canker in Europe?Fusarium circinatum [...] Read more.
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Open AccessArticle Disturbance Alters the Relative Importance of Topographic and Biogeochemical Controls on Microbial Activity in Temperate Montane Forests
Forests 2018, 9(2), 97; https://doi.org/10.3390/f9020097
Received: 7 December 2017 / Revised: 3 February 2018 / Accepted: 12 February 2018 / Published: 24 February 2018
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Abstract
Fire and pathogen-induced tree mortality are the two dominant forms of disturbance in Western U.S. montane forests. We investigated the consequences of both disturbance types on the controls of microbial activity in soils from 56 plots across a topographic gradient one year after
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Fire and pathogen-induced tree mortality are the two dominant forms of disturbance in Western U.S. montane forests. We investigated the consequences of both disturbance types on the controls of microbial activity in soils from 56 plots across a topographic gradient one year after the 2012 High Park wildfire in Colorado. Topsoil biogeochemistry, soil CO2 efflux, potential exoenzyme activities, and microbial biomass were quantified in plots that experienced fire disturbance, beetle disturbance, or both fire and beetle disturbance, and in plots where there was no recent evidence of disturbance. Soil CO2 efflux, N-, and P-degrading exoenzyme activities in undisturbed plots were positively correlated with soil moisture, estimated from a topographic wetness index; coefficient of determinations ranged from 0.5 to 0.65. Conversely, the same estimates of microbial activities from fire-disturbed and beetle-disturbed soils showed little correspondence to topographically inferred wetness, but demonstrated mostly negative relationships with soil pH (fire only) and mostly positive relationships with DOC/TDN (dissolved organic carbon/total dissolved nitrogen) ratios for both disturbance types. The coefficient of determination for regressions of microbial activity with soil pH and DOC/TDN reached 0.8 and 0.63 in fire- and beetle-disturbed forests, respectively. Drivers of soil microbial activity change as a function of disturbance type, suggesting simple mathematical models are insufficient in capturing the impact of disturbance in forests. Full article
(This article belongs to the Special Issue How Topography Impacts Forests under Global Change?)
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Open AccessArticle Application of GIS to Empirical Windthrow Risk Model in Mountain Forested Landscapes
Forests 2018, 9(2), 96; https://doi.org/10.3390/f9020096
Received: 12 December 2017 / Revised: 16 February 2018 / Accepted: 16 February 2018 / Published: 22 February 2018
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Abstract
Norway spruce dominates mountain forests in Europe. Natural variations in the mountainous coniferous forests are strongly influenced by all the main components of forest and landscape dynamics: species diversity, the structure of forest stands, nutrient cycling, carbon storage, and other ecosystem services. This
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Norway spruce dominates mountain forests in Europe. Natural variations in the mountainous coniferous forests are strongly influenced by all the main components of forest and landscape dynamics: species diversity, the structure of forest stands, nutrient cycling, carbon storage, and other ecosystem services. This paper deals with an empirical windthrow risk model based on the integration of logistic regression into GIS to assess forest vulnerability to wind-disturbance in the mountain spruce forests of Šumava National Park (Czech Republic). It is an area where forest management has been the focus of international discussions by conservationists, forest managers, and stakeholders. The authors developed the empirical windthrow risk model, which involves designing an optimized data structure containing dependent and independent variables entering logistic regression. The results from the model, visualized in the form of map outputs, outline the probability of risk to forest stands from wind in the examined territory of the national park. Such an application of the empirical windthrow risk model could be used as a decision support tool for the mountain spruce forests in a study area. Future development of these models could be useful for other protected European mountain forests dominated by Norway spruce. Full article
(This article belongs to the Special Issue Forest Landscape Ecology: Linking Past, Present, and Future Data)
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Open AccessFeature PaperArticle Enhancing the Estimation of Stem-Size Distributions for Unimodal and Bimodal Stands in a Boreal Mixedwood Forest with Airborne Laser Scanning Data
Forests 2018, 9(2), 95; https://doi.org/10.3390/f9020095
Received: 31 January 2018 / Revised: 16 February 2018 / Accepted: 17 February 2018 / Published: 18 February 2018
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Abstract
Stem size distribution (SSD), which describes tree frequencies in diameter classes within an area, has a variety of direct and indirect applications that are critical for forest management. In this study, we evaluated which structural characteristics derived from Airborne Laser Scanning (ALS) data
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Stem size distribution (SSD), which describes tree frequencies in diameter classes within an area, has a variety of direct and indirect applications that are critical for forest management. In this study, we evaluated which structural characteristics derived from Airborne Laser Scanning (ALS) data were best able to differentiate between unimodal and bimodal stands in a managed boreal mixedwood forest in Alberta, Canada. We then used wall-to-wall ALS data to predict (for 20 m-by-20 m grid cells) the parameters of a Weibull SSD in unimodal cells, and a Finite Mixture Model (FMM) in bimodal cells. The resulting SSDs were evaluated for their fit to ground plot-measured SSDs using an Error Index (EI). We found that the variance of ALS return heights was the best metric for differentiating between unimodal and bimodal stands, with a classification accuracy of 77%. Parameters of both the Weibull and FMM distributions were accurately predicted (r2 ~ 0.5, Root Mean Square Error (RMSE) ~ 30%), and that differentiating for modality prior to estimating SSD improved the accuracy of estimates (EI of 49.13 with differentiation versus 51.31 without differentiation). Unique to our presented approach is the stratification by SSD modality prior to the modelling of distributions. To achieve this, we apply a threshold to an ALS metric that allows SSD modality to be distinguished for each cell at the landscape level, and this a priori information is then used to ensure that the appropriate distribution is modelled. Our approach is parsimonious and efficient, enabling improved accuracy in SSD estimation across diverse landscapes when ALS data is the sole data source. Full article
(This article belongs to the Section Forest Inventory, Quantitative Methods and Remote Sensing)
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Open AccessArticle Resistance of a Local Ecotype of Castanea sativa to Dryocosmus kuriphilus (Hymenoptera: Cynipidae) in Southern Italy
Forests 2018, 9(2), 94; https://doi.org/10.3390/f9020094
Received: 16 January 2018 / Revised: 8 February 2018 / Accepted: 11 February 2018 / Published: 16 February 2018
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Abstract
The cynipid Dryocosmus kuriphilus is the most impactful invasive pest of Castanea sativa copse woods and orchards currently reported from many European countries. A low impact solution for the containment of this pest could be the use of resistant trees. We examined the
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The cynipid Dryocosmus kuriphilus is the most impactful invasive pest of Castanea sativa copse woods and orchards currently reported from many European countries. A low impact solution for the containment of this pest could be the use of resistant trees. We examined the resistance of the red salernitan ecotype (RSE) of C. sativa to D. kuriphilus and carried out a morphological characterization of this ecotype’s plants and fruits. From November 2015 to May 2017 we observed and recorded the percentage of infested buds, healthy leaves and shoots on about 50 chestnut trees, together with the number, size, and position of galls, and the number of eggs laid by the gall wasps into the buds and the number of larvae inside the galls. We showed a progressive mortality of cynipid larvae up to the starting point of galls development when almost total larval mortality was recorded. This suggests that RSE trees have a moderate resistance to D. kuriphilus; however, resistance acts at different levels, resulting in fewer eggs being deposited, a low number of larvae reaching the complete development, and a low number of galls on the branches. Moreover, the galls on resistant trees are smaller than the susceptible ones, so the larvae are more exposed to parasitization. Full article
(This article belongs to the Special Issue Ecology and Management of Invasive Species in Forest Ecosystems)
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Open AccessFeature PaperArticle Charcoal Increases Microbial Activity in Eastern Sierra Nevada Forest Soils
Forests 2018, 9(2), 93; https://doi.org/10.3390/f9020093
Received: 10 January 2018 / Revised: 7 February 2018 / Accepted: 14 February 2018 / Published: 16 February 2018
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Abstract
Fire is an important component of forests in the western United States. Not only are forests subjected to wildfires, but fire is also an important management tool to reduce fuels loads. Charcoal, a product of fire, can have major impacts on carbon (C)
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Fire is an important component of forests in the western United States. Not only are forests subjected to wildfires, but fire is also an important management tool to reduce fuels loads. Charcoal, a product of fire, can have major impacts on carbon (C) and nitrogen (N) cycling in forest soils, but it is unclear how these effects vary by dominant vegetation. In this study, soils collected from Jeffrey pine (JP) or lodgepole pine (LP) dominated areas and amended with charcoal derived from JP or LP were incubated to assess the importance of charcoal on microbial respiration and potential nitrification. In addition, polyphenol sorption was measured in unamended and charcoal-amended soils. In general, microbial respiration was highest at the 1% and 2.5% charcoal additions, but charcoal amendment had limited effects on potential nitrification rates throughout the incubation. Microbial respiration rates decreased but potential nitrification rates increased over time across most treatments. Increased microbial respiration may have been caused by priming of native organic matter rather than the decomposition of charcoal itself. Charcoal had a larger stimulatory effect on microbial respiration in LP soils than JP soils. Charcoal type had little effect on microbial processes, but polyphenol sorption was higher on LP-derived than JP-derived charcoal at higher amendment levels despite surface area being similar for both charcoal types. The results from our study suggest that the presence of charcoal can increase microbial activity in soils, but the exact mechanisms are still unclear. Full article
(This article belongs to the Special Issue Carbon, Nitrogen and Phosphorus Cycling in Forest Soils)
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Open AccessArticle Drought Impact on Phenology and Green Biomass Production of Alpine Mountain Forest—Case Study of South Tyrol 2001–2012 Inspected with MODIS Time Series
Forests 2018, 9(2), 91; https://doi.org/10.3390/f9020091
Received: 12 January 2018 / Revised: 10 February 2018 / Accepted: 14 February 2018 / Published: 16 February 2018
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Abstract
Ecological balance and biodiversity of the alpine forest is endangered by global and local climatic extremes. It spurs a need for comprehensive forest monitoring, including in depth analyses of drought impact on the alpine woodland ecosystems. Addressing an arising knowledge gap, we identified
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Ecological balance and biodiversity of the alpine forest is endangered by global and local climatic extremes. It spurs a need for comprehensive forest monitoring, including in depth analyses of drought impact on the alpine woodland ecosystems. Addressing an arising knowledge gap, we identified and analyzed 2002–2012 aridity related responses within the alpine mountain forest of South Tyrol. The study exploited a S-mode PCA (Principal Component Analysis) based synergy between meteorological conditions rendered by the scPDSI (self-calibrated Palmer Drought Severity Index) and forest status approximated through MODIS (Moderate Resolution Imaging Spectroradiometer) derived NDVI (Normalized Difference Vegetation Index) and NDII7 (Normalized Difference Infrared Index based on MODIS band 7) time series. Besides characterizing predominant forest temporal response to drought, we identified corresponding spatial footprints of drought impact, as well as examined aridity-related changes in forest phenology and biomass production. The latter was further evaluated in relation to forest type, elevation, aspect and slope. Recognized meteorological conditions highlighted: prolonged 2003–2007 mild to extreme drought, and overall regional drying tendencies. Arising remotely sensed forest responses accounted on localized decline in foliage water content and/or photosynthetic activity, but also indicated regions where forest condition improved despite the meteorological stress. Perceived variability in the forest response to drought conditions was governed by geographic location, species structure, elevation and exposition, and featured complexity of the alpine forest ecosystem. Among the inspected biophysical factors elevation had the strongest influence on forest phenology and green biomass production under meteorological stress conditions. Stands growing above 1400 m a.s.l. demonstrated initial increase in annual biomass growth at the beginning of the dry spell in 2003. Conversely, woodlands at lower altitudes comprising considerable share of hardwood species were more prone to biomass decline in 2003, but experienced an overall upturn in biomass production during the following years of the dry spell. Aspect showed moderate effect on drought-related phenology and green biomass production responses. Diverse forest ecosystem responses identified in this study were in line with known local and regional analyses, but also shed some new light on drought induced alternation of forest status. Full article
(This article belongs to the Special Issue Remotely Sensing of Drought-Induced Forest Change and Recovery)
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Open AccessArticle Use of Nuclear Microsatellite Loci for Evaluating Genetic Diversity of Selected Populations of Picea abies (L.) Karsten in the Czech Republic
Forests 2018, 9(2), 92; https://doi.org/10.3390/f9020092
Received: 8 December 2017 / Revised: 13 February 2018 / Accepted: 13 February 2018 / Published: 15 February 2018
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Abstract
DNA polymorphism at nine nuclear microsatellites of nine selected naturally-regenerated Norway spruce populations growing mainly within gene conservation units in different parts of the Czech Republic was studied. To verify the genetic quality of the selected gene conservation unit, we analyzed nine Norway
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DNA polymorphism at nine nuclear microsatellites of nine selected naturally-regenerated Norway spruce populations growing mainly within gene conservation units in different parts of the Czech Republic was studied. To verify the genetic quality of the selected gene conservation unit, we analyzed nine Norway spruce subpopulations from gene conservation unit GZ 102–Orlické hory. Genetic parameters can be used in state administrative decision making on including stands into gene conservation units. The level of genetic diversity within 17 investigated Czech Norway spruce units was relatively high. Mean values for the number of different alleles ranged from 12.2 (population SM 08) to 16.2 (subpopulation SM T4). The values of observed heterozygosity (Ho) ranged from 0.65 to 0.80 and expected heterozygosity (He) from 0.74 to 0.81. Pairwise population FST values ranging from 0.006 to 0.027 indicated low genetic differentiation between units, and values of Nei’s genetic distance among Norway spruce units ranged from 0.046 to 0.168, thus structuring of the investigated Norway spruce units was confirmed. Closer genetic similarity was seen in subpopulations from the gene conservation unit in Orlické hory than in the studied populations from other genetic conservation units. Additionally, the populations SM 01 and SM 05, both of Hurst ecotypes, were the closest to one another and the populations of mountain and alpine ecotypes were assembled into another group. Full article
(This article belongs to the Special Issue Genetics and Genomics of Forest Trees)
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Open AccessArticle Reducing Firewood Movement by the Public: Use of Survey Data to Assess and Improve Efficacy of a Regulatory and Educational Program, 2006–2015
Forests 2018, 9(2), 90; https://doi.org/10.3390/f9020090
Received: 20 December 2017 / Revised: 9 February 2018 / Accepted: 11 February 2018 / Published: 14 February 2018
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Abstract
This paper describes a program of policy management and research from 2006 through 2015. It focuses on regulator efforts to understand and address challenges presented by dispersal of forest diseases and invasive pests in firewood by the camping public. Five surveys conducted at
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This paper describes a program of policy management and research from 2006 through 2015. It focuses on regulator efforts to understand and address challenges presented by dispersal of forest diseases and invasive pests in firewood by the camping public. Five surveys conducted at two-year intervals informed these efforts. The first survey in 2006 benchmarked campers’ awareness of forest threats by invasive species, their evaluations of firewood supplied at and near Wisconsin state parks, and their compliance with firewood movement rules which had been implemented that year. The 2008 survey tested for improvements in awareness and compliance and investigated campers’ motivations. The motivation research showed that calculated, normative, and social motivations are all important to rule compliance in the camping context. Surveys in 2010, 2012, and 2014 confirmed these results and guided education and outreach efforts, adjustments to firewood movement rules for Wisconsin state parks and forests, and improvements to firewood supplies at state campgrounds. The survey sequence as a whole revealed that: (1) compliance improves dramatically in early program years and then levels off, suggesting that it may be unrealistic and cost ineffective to strive for 100% compliance in similar regulatory contexts; (2) persistence in messaging is important in building awareness and motivation; and (3) regulation and persuasion based on motivational principles can extend beyond specific situations where informing and regulating take place, suggesting that public properties can be useful venues for encouraging other types of environmentally responsible behavior. Full article
(This article belongs to the Special Issue Understanding and Managing Emerald Ash Borer Impacts on Ash Forests)
Open AccessArticle Modeling Ecosystem Services for Park Trees: Sensitivity of i-Tree Eco Simulations to Light Exposure and Tree Species Classification
Forests 2018, 9(2), 89; https://doi.org/10.3390/f9020089
Received: 18 January 2018 / Revised: 8 February 2018 / Accepted: 10 February 2018 / Published: 13 February 2018
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Abstract
Ecosystem modeling can help decision making regarding planting of urban trees for climate change mitigation and air pollution reduction. Algorithms and models that link the properties of plant functional types, species groups, or single species to their impact on specific ecosystem services have
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Ecosystem modeling can help decision making regarding planting of urban trees for climate change mitigation and air pollution reduction. Algorithms and models that link the properties of plant functional types, species groups, or single species to their impact on specific ecosystem services have been developed. However, these models require a considerable effort for initialization that is inherently related to uncertainties originating from the high diversity of plant species in urban areas. We therefore suggest a new automated method to be used with the i-Tree Eco model to derive light competition for individual trees and investigate the importance of this property. Since competition depends also on the species, which is difficult to determine from increasingly used remote sensing methodologies, we also investigate the impact of uncertain tree species classification on the ecosystem services by comparing a species-specific inventory determined by field observation with a genus-specific categorization and a model initialization for the dominant deciduous and evergreen species only. Our results show how the simulation of competition affects the determination of carbon sequestration, leaf area, and related ecosystem services and that the proposed method provides a tool for improving estimations. Misclassifications of tree species can lead to large deviations in estimates of ecosystem impacts, particularly concerning biogenic volatile compound emissions. In our test case, monoterpene emissions almost doubled and isoprene emissions decreased to less than 10% when species were estimated to belong only to either two groups instead of being determined by species or genus. It is discussed that this uncertainty of emission estimates propagates further uncertainty in the estimation of potential ozone formation. Overall, we show the importance of using an individual light competition approach and explicitly parameterizing all ecosystem functions at the species-specific level. Full article
(This article belongs to the Special Issue Growth and Ecosystem Services of Urban Trees)
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Open AccessArticle Genome-Wide Analysis of Gene and microRNA Expression in Diploid and Autotetraploid Paulownia fortunei (Seem) Hemsl. under Drought Stress by Transcriptome, microRNA, and Degradome Sequencing
Forests 2018, 9(2), 88; https://doi.org/10.3390/f9020088
Received: 14 January 2018 / Revised: 7 February 2018 / Accepted: 9 February 2018 / Published: 13 February 2018
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Abstract
Drought is a common and recurring climatic condition in many parts of the world, and it can have disastrous impacts on plant growth and development. Many genes involved in the drought response of plants have been identified. Transcriptome, microRNA (miRNA), and degradome analyses
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Drought is a common and recurring climatic condition in many parts of the world, and it can have disastrous impacts on plant growth and development. Many genes involved in the drought response of plants have been identified. Transcriptome, microRNA (miRNA), and degradome analyses are rapid ways of identifying drought-responsive genes. The reference genome sequence of Paulownia fortunei (Seem) Hemsl. is now available, which makes it easier to explore gene expression, transcriptional regulation, and post-transcriptional in this species. In this study, four transcriptome, small RNA, and degradome libraries were sequenced by Illumina sequencing, respectively. A total of 258 genes and 11 miRNAs were identified for drought-responsive genes and miRNAs in P. fortunei. Degradome sequencing detected 28 miRNA target genes that were cleaved by members of nine conserved miRNA families and 12 novel miRNAs. The results here will contribute toward enriching our understanding of the response of Paulownia fortunei trees to drought stress and may provide new direction for further experimental studies related the development of molecular markers, the genetic map construction, and other genomic research projects in Paulownia. Full article
(This article belongs to the Special Issue Genetics and Genomics of Forest Trees)
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Open AccessArticle Transcriptome Analysis of the Biosynthesis of Anthocyanins in Begonia semperflorens under Low-Temperature and High-Light Conditions
Forests 2018, 9(2), 87; https://doi.org/10.3390/f9020087
Received: 14 November 2017 / Revised: 29 January 2018 / Accepted: 7 February 2018 / Published: 13 February 2018
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Abstract
Anthocyanins are considered a stress indicator due to their involvement in the response to many stresses including high light (HL) and low temperature (LT). With the development of transcriptomics, it is necessary to find the different and common points in the mechanisms of
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Anthocyanins are considered a stress indicator due to their involvement in the response to many stresses including high light (HL) and low temperature (LT). With the development of transcriptomics, it is necessary to find the different and common points in the mechanisms of LT-induced and HL-induced anthocyanin biosynthesis. In the present study, we determined the transcriptomes of Begonia semperflorens leaves under three different conditions (normal growing conditions (CK), HL, and LT). To validate the differentially expressed genes (DEGs), we selected four core genes involved in anthocyanin biosynthesis to perform real-time reverse transcription-quantitative PCR (RT-qPCR), and then determined anthocyanin content. In total, 94,880 unigenes with a mean length of 635 bp were assembled. The N50 values of the transcripts and unigenes were 2286 bp and 1064 bp, respectively. The functional annotations of the unigenes were analysed against five protein databases. DEGs related to anthocyanin biosynthesis, transportation, and regulation were identified. We also analysed the enrichment pathway, and the differences in mechanisms of anthocyanin induced under low-temperature and high-light conditions are discussed in this paper. This study is the first to examine broad-scale gene expression in Begonia semperflorens. By identifying DEGs regulated by both LT and HL conditions, we found that anthocyanin accumulation was employed as a common strategy by Begonia seedlings in resisting LT and HL stress. By identifying DEGs regulated differently by LT and HL conditions, we found that Begonia seedlings also had some different strategies for resisting LT and HL stresses: anthocyanins were biosynthesized under HL condition, while lignin, proanthocyanidins, and anthocyanins were biosynthesized under LT condition. Full article
(This article belongs to the Section Forest Ecophysiology and Biology)
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Open AccessArticle Relationships between Wood Formation and Cambium Phenology on the Tibetan Plateau during 1960–2014
Forests 2018, 9(2), 86; https://doi.org/10.3390/f9020086
Received: 29 January 2018 / Revised: 8 February 2018 / Accepted: 9 February 2018 / Published: 13 February 2018
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Abstract
The variability of tree stem phenology plays a critical role in determining the productivity of forest ecosystems. Therefore, we aim to identify the relationships between the timings of cambium phenology, and forest growth in terms of tree-ring width over a long-term scale. A
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The variability of tree stem phenology plays a critical role in determining the productivity of forest ecosystems. Therefore, we aim to identify the relationships between the timings of cambium phenology, and forest growth in terms of tree-ring width over a long-term scale. A meta-analysis was performed that combined the timings of xylem formation, which were calculated by a tree-ring formation model of the VS (Vaganov-Shashkin)-oscilloscope during the period 1960–2014, and a tree-ring width series at 20 composite sites on the Tibetan Plateau. Both the start and length of the growing season significantly affected the formation of wood at 70% of the 20 composite sites within the study region. A wider tree ring probably resulted from an earlier start and a longer duration of the growing season. The influence of ending dates on tree-ring width was less evident, and more site-dependent. Weak relationships were identified between the start and end of the growing season at 85% of the composite sites. Compared to the monitoring results, which could only detect the relationships between cambium phenology and xylem cell production from a limited number of trees and years, our long-term relationships deepened such connections, and therefore should be used to improve mechanism models for the accurate evaluating and predicting of wood production and carbon sequestration in forest ecosystems under current and future climate change. Full article
(This article belongs to the Section Forest Ecology and Management)
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Open AccessArticle Estimation and Extrapolation of Tree Parameters Using Spectral Correlation between UAV and Pléiades Data
Forests 2018, 9(2), 85; https://doi.org/10.3390/f9020085
Received: 20 December 2017 / Revised: 27 January 2018 / Accepted: 8 February 2018 / Published: 11 February 2018
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Abstract
The latest technological advances in space-borne imagery have significantly enhanced the acquisition of high-quality data. With the availability of very high-resolution satellites, such as Pléiades, it is now possible to estimate tree parameters at the individual level with high fidelity. Despite innovative advantages
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The latest technological advances in space-borne imagery have significantly enhanced the acquisition of high-quality data. With the availability of very high-resolution satellites, such as Pléiades, it is now possible to estimate tree parameters at the individual level with high fidelity. Despite innovative advantages on high-precision satellites, data acquisition is not yet available to the public at a reasonable cost. Unmanned aerial vehicles (UAVs) have the practical advantage of data acquisition at a higher spatial resolution than that of satellites. This study is divided into two main parts: (1) we describe the estimation of basic tree attributes, such as tree height, crown diameter, diameter at breast height (DBH), and stem volume derived from UAV data based on structure from motion (SfM) algorithms; and (2) we consider the extrapolation of the UAV data to a larger area, using correlation between satellite and UAV observations as an economically viable approach. Results have shown that UAVs can be used to predict tree characteristics with high accuracy (i.e., crown projection, stem volume, cross-sectional area (CSA), and height). We observed a significant relation between extracted data from UAV and ground data with R2 = 0.71 for stem volume, R2 = 0.87 for height, and R2 = 0.60 for CSA. In addition, our results showed a high linear relation between spectral data from the UAV and the satellite (R2 = 0.94). Overall, the accuracy of the results between UAV and Pléiades was reasonable and showed that the used methods are feasible for extrapolation of extracted data from UAV to larger areas. Full article
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Open AccessReview Tissue Culture of Corymbia and Eucalyptus
Forests 2018, 9(2), 84; https://doi.org/10.3390/f9020084
Received: 15 December 2017 / Revised: 7 February 2018 / Accepted: 7 February 2018 / Published: 9 February 2018
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Abstract
Eucalypts are among the world’s most widely planted trees, but the productivity of eucalypt plantations is limited by their often-low amenability to true-to-type propagation from cuttings. An alternative approach to cutting propagation is tissue culture, which can be used to micropropagate valuable genotypes
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Eucalypts are among the world’s most widely planted trees, but the productivity of eucalypt plantations is limited by their often-low amenability to true-to-type propagation from cuttings. An alternative approach to cutting propagation is tissue culture, which can be used to micropropagate valuable genotypes rapidly while simultaneously preserving germplasm in vitro. This review describes the use of tissue culture methods such as shoot culture, organogenesis, and somatic embryogenesis for micropropagating eucalypts. This review also discusses the use of cool storage, encapsulation, and cryopreservation methods for preserving eucalypt germplasm and delaying tissue maturation under minimal-growth conditions. Full article
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Open AccessArticle Mixing Effects in Norway Spruce—European Beech Stands Are Modulated by Site Quality, Stand Age and Moisture Availability
Forests 2018, 9(2), 83; https://doi.org/10.3390/f9020083
Received: 11 January 2018 / Revised: 2 February 2018 / Accepted: 7 February 2018 / Published: 9 February 2018
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Abstract
Although mixing tree species is considered an efficient risk-reduction strategy in the face of climate change, the conditions where mixtures are more productive than monocultures are under ongoing debate. Generalizations have been difficult because of the variety of methods used and due to
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Although mixing tree species is considered an efficient risk-reduction strategy in the face of climate change, the conditions where mixtures are more productive than monocultures are under ongoing debate. Generalizations have been difficult because of the variety of methods used and due to contradictory findings regarding the effects of the species investigated, mixing proportions, and many site and stand conditions. Using data from 960 plots of the Swiss National Forest Inventory data, we assessed whether Picea abies (L.) Karst–Fagus sylvatica L. mixed stands are more productive than pure stands, and whether the mixing effect depends on site- or stand-characteristics. The species proportions were estimated using species proportion by area, which depends on the maximum stand basal area of an unmanaged stand (BAmax). Four different alternatives were used to estimate BAmax and to investigate the effect of these differing alternatives on the estimated mixture effect. On average, the mixture had a negative effect on the growth of Picea abies. However, this effect decreased as moisture availability increased. Fagus sylvatica grew better in mixtures and this effect increased with site quality. A significant interaction between species proportions and quadratic mean diameter, a proxy for stand age, was found for both species: the older the stand, the better the growth of Fagus sylvatica and the lower the growth of Picea abies. Overyielding was predicted for 80% of the investigated sites. The alternative to estimate BAmax weakly modulated the estimated mixture effect, but it did not affect the way mixing effects changed with site characteristics. Full article
(This article belongs to the Section Forest Ecology and Management)
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