Forests, Volume 12, Issue 6 (June 2021) – 164 articles

The quantification of post-disturbance root reinforcement (RR) recovery dynamics is of paramount importance for the optimisation of forest ecosystem services and natural hazards risk management in mountain regions. In this work we analyse the long-term root reinforcement dynamic of spruce forests combining data of the Swiss National Forest Inventory with data on root distribution and root mechanical properties. The results show that root reinforcement recovery depends primarily on stand altitude and slope inclination. The maximum root reinforcement recovery rate is reached at circa 100 years. RR increases continuously with different rates for stand ages over 200 years. These results shows that RR in spruce stands varies considerably depending on the local conditions and that its recovery after disturbances requires decades. The new method applied in this study allowed for the first time to quantify the long term dynamics of RR in spruce stands supporting new quantitative approaches for the analysis of shallow landslides disposition in different disturbance regimes of forests. Full article

Due to traditional forest management, the primary goal of which is the production of raw wood material, commercial forest stands are characterized by low biodiversity. At the same time, commercial forests make up the majority of forests in the Central European region, which means a significant impact on the biodiversity of the entire large region. Saproxylic species of organisms are a frequently used criterion of biodiversity in forests. Based upon the analysis of 155 scientific works, this paper defines the fundamental attributes of the active management supporting biodiversity as well as the preservation of the production function. Using these attributes, a model management proposal was created for three tree species, which takes into account the results of research carried out in the territory of the University Forest Enterprise of the Czech University of Life Sciences Prague, since 2019. The optimum constant volume of deadwood in commercial stands was set at 40–60 m³/ha, 20% of which should be standing deadwood. The time framework is scheduled for an average rotation period of the model tree species, while the location of deadwood and frequency of enrichment must comply with the rate of decomposition, the requirement for the bulkiest dimensions of deadwood possible, and the planned time of tending and regeneration operations in accordance with the models used in the Czech Republic. The goal of active management is to maintain the continuity of suitable habitats for sensitive and endangered species. The estimates of the value of retained wood for decomposition can be as high as 45–70 EUR/ha/year for spruce and beech, and about 30 EUR /ha/year for oak. Full article

Shrub encroachment of grassland and woodland ecosystems can alter wildfire behaviour and threaten ecological values. Australian fire managers are using mechanical mastication to reduce the fire risk in encroached ecosystems but are yet to evaluate its effectiveness or ecological impact. We asked: (1) How does fuel load and structure change following mastication?; (2) Is mastication likely to affect wildfire rates of spread and flame heights?; and (3) What is the impact of mastication on flora species richness and diversity? At thirteen paired sites (masticated versus control; n = 26), located in Victoria, Australia, we measured fuel properties (structure, load and hazard) and floristic diversity (richness and Shannon’s H) in 400 mP² plots. To quantify the effects of mastication, data were analysed using parametric and non-parametric paired sample techniques. Masticated sites were grouped into two categories, 0–2 and 3–4 years post treatment. Fire behaviour was predicted using the Dry Eucalypt Forest Fire Model. Mastication with follow-up herbicide reduced the density of taller shrubs, greater than 50 cm in height, for at least 4 years. The most recently masticated sites (0–2 years) had an almost 3-fold increase in dead fine fuel loads and an 11-fold increase in dead coarse fuel loads on the forest floor compared with the controls. Higher dead coarse fuel loads were still evident after 3–4 years. Changes to fuel properties produced a reduction in predicted flame heights from 22 m to 5–6 m under severe fire weather conditions, but no change in the predicted fire rate of spread. Reductions in flame height would be beneficial for wildfire suppression and could reduce the damage to property from wildfires. Mastication did not have a meaningful effect on native species diversity, but promoted the abundance of some exotic species. Full article

Members of the genus Fusarium and related genera are important components of many ecosystems worldwide and are responsible for many plant diseases. However, the structure of beech litter-inhabiting Fusarium communities and their potential role in reducing the natural regeneration of European beech are not well understood. To address this issue, we examined Fusarium communities in the litter of uneven-aged, old-growth beech-dominated forests in the Carpathians (Poland) and in the Alps (Austria), and in a managed beech stand (Poland). The fungi inhabiting beech litter were investigated using beechnuts and pine seedlings as bait. The pathogenicity of the most common species was investigated by inoculating beech germinants. Fusarium spp. were identified based on morphology and DNA sequence comparisons of RPB2 and TEF1-α genes, combined with phylogenetic analyses. Twelve fungal species were identified from 402 isolates, including nine known and three currently undescribed species. The isolates resided in three species complexes within the genus Fusarium. These were the F. oxysporum (one taxon), F. sambucinum (three taxa), and F. tricinctum (six taxa) species complexes. In addition, one isolate was assigned to the genus Neocosmospora, and one isolate could be placed within the genus Fusicolla. The most frequently isolated fungi from beechnuts and beech germinants were F. avenaceum (Fr.) Sacc., F. sporotrichioides Sherb. and Fusarium sp. B. The structure and abundance of species within Fusarium communities varied by beech forest type. The species richness of Fusarium spp. was greatest in old-growth beech-dominated stands, while abundances of Fusarium spp. were higher in managed beech-dominated stands. Pathogenicity tests showed that all four Fusarium species isolated from beechnuts and beech germinants could cause germinants to rot beech, suggesting that these fungi may play a negative role in the natural beech regeneration. Full article

Sawmilling operations represent one of the most important phases of the wood supply chain, because they connect the conversion flow of raw materials into finite products. In order to maintain a high volume of processed wood, sawmills usually adopt different processing strategies in terms of equipment and methods, which can increase the value or volume of the lumber produced from logs. In this study, the performance of small-scale sawmilling operations was monitored, whilst also evaluating the exposure of workers to harmful factors. An assessment of time consumption, productivity, and main ergonomics was conducted during the use of a manually driven bandsaw. In addition, the exposure to noise was investigated to complement the knowledge in this regard. The results indicated a rather high time utilization in productive tasks, which may come at the expense of exposure to noise and to poor working postures. The modelling approach resulted in statistically significant time consumption models for different phases (blade adjustment, effective sawing, returning, unloading lumber, and loading and fixing lumber). The exposure to noise was close to 92 dB (A) (8 h) and, therefore, the level of emitted noise is likely to depend on the condition of the used blades, species sawn and on the dimensional characteristics of the logs. In terms of ergonomic risks, the poorest postures were those related to tasks such as moving the logs, loading the logs, fixing the logs, rotating and removing the logs, as well as unloading the lumber. Full article

When adopted, wildlife protection policies in Canadian forests typically cover large areas and affect multiple economic agents working in these landscapes. Such measures are likely to increase the costs of timber for forestry companies operating in the area, which may hinder their acceptance of the policies unless harvesting remains profitable. We propose a bi-level wildlife protection problem that accounts for the profit-maximizing behavior of forestry companies operating in an area subject to protection. We consider the regulator with a wildlife protection mandate and forestry companies licensed to harvest public forest lands. We depict the relationship between the regulator and forestry companies as a leader-follower Stackelberg game. The leader sets the protected area target for each license area and the followers adjust their strategies to maximize payoffs while meeting the protection target set by the leader. The leader’s objective is to maximize the area-wide protection of spatially contiguous habitat while accounting for the followers’ profit-maximizing behavior. We apply the approach to investigate habitat protection policies for woodland caribou in the Churchill range, Ontario, Canada. We compare the game-theoretic solutions with solutions that do not consider the forest companies’ objectives and also with solutions equalizing the revenue losses among the companies. Full article

Responsible forest management requires accounting for adverse environmental effects, such as increased nutrient export to water courses. We constructed a spatially-distributed nutrient balance model NutSpaFHy that extends the hydrological model SpaFHy by introducing a grid-based nutrient balance sub-model and a conceptual solute transport routine to approximate total nitrogen (N) and phosphorus (P) export to streams. NutSpaFHy uses openly-available Multi-Source National Forest Inventory data, soil maps, topographic databases, location of water bodies, and meteorological variables as input, and computes nutrient processes in monthly time-steps. NutSpaFHy contains two calibrated parameters both for N and P, which were optimized against measured N and P concentrations in runoff from twelve forested catchments distributed across Finland. NutSpaFHy was independently tested against six catchments. The model produced realistic nutrient exports. For one catchment, we simulated 25 scenarios, where clear-cuts were located differently with respect to distance to water body, location on mineral or peat soil, and on sites with different fertility. Results indicate that NutSpaFHy can be used to identify current and future nutrient export hot spots, allowing comparison of logging scenarios with variable harvesting area, location and harvest techniques, and to identify acceptable scenarios that preserve the wood supply whilst maintaining acceptable level of nutrient export. Full article

Forest biomass is a sustainable source of renewable energy and a valuable alternative to finite fossil fuels. However, its overharvesting may lead to soil nutrient depletion and threaten future stand productivity, as well as affect the habitat for biodiversity. This paper provides quantitative data on biomass removal, fine woody debris [d ≤ 7 cm], and coarse woody debris [d > 7 cm] left on the forest floor in whole tree harvesting systems. Using tree allometric equations and inventory field methods for woody debris estimation, we assessed biomass removal on nine fuelwood harvesting sites in Central France, as well as fine and coarse woody debris left on the sites. The aboveground biomass estimates showed a high variability between the studied sites, it varied between 118 and 519 Mg ha⁻¹. However, less variability was found among sites managed as coppice-with-standards 174 ± 56 Mg ha⁻¹. Exported biomass was 107 ± 42 Mg ha⁻¹ on average, including 35 ± 9% of fine wood. The amounts of both fine and coarse woody debris left on sites were generally less than 10% of the total harvested biomass in 2/3 of the studied sites. These amounts are lower than the minimum retention levels recommended by the sustainable forest biomass harvesting guidelines. Therefore, more technical effort and additional management measures should be taken to ensure more woody debris, especially in poor forest soils and thus, to guarantee a sustainable biomass harvesting. Full article

Urban forests offer multiple functions: they can balance negative effects from the environment and provide the public with a place for leisure and recreation. Hence, urban forests are crucial to urban ecology and have been widely studied. In addition, relevant study results were applied for policymaking in urban development and forest park management. This study evaluated the ecological value of the Sinhua Forest Park and examined whether the socioeconomic background of participants influences their willingness to pay (WTP) for ecological conservation. Questionnaires were distributed to visitors in the Sinhua Forest Park in Tainan, Taiwan, and the payment card format of the contingent valuation method was employed to evaluate the ecological value. The results showed that the visitors had an annual WTP of $22.01 per person. However, when samples with protest responses were excluded, the WTP rose to $24.58. By considering the total number of visitors of a year, the total ecological value was $1,426,964.14/year and reached $1,593,257.31/year after excluding the protest samples. This study also analyzed participants’ within-variable socioeconomic background (e.g., gender and education) and discovered that male participants who are aged 60 years or older, with an education level of senior/vocational high school, and those who visited green spaces two to three times per week presented a high WTP score on average. A Tobit regression model was employed for examination, and the results indicated that participants’ education and frequency of visiting green spaces significantly influenced their WTP for the ecological conservation of the Sinhua Forest Park. Full article

Soil microbial communities play an important role in maintaining the ecosystem during forest secondary succession. However, the underlying mechanisms that drive change in soil microbial community structures during secondary succession remain poorly defined in species-rich subtropical coniferous forests. In this study, Illumina high-throughput sequencing was used to analyze the variations in soil microbial community structures during forest secondary succession in subtropical coniferous forests in China. The role of soil properties and plant diversity in affecting soil bacterial and fungal communities was determined using random forest and structural equation models. Highly variable soil microbial diversity was observed in different stages of secondary succession. Bacterial community diversity rose from early to middle and late successional stages, whereas fungal community diversity increased from early to middle successional stages and then declined in the late stage. The relative abundance of Acidobacteria, Gemmatimonadetes, Eremiobacterota(WPS-2), Rokubacteria, and Mortierellomycota increased during succession, whereas the relative abundance of Ascomycota and Mucoromycota decreased. The community composition and diversity of the soil microbial community were remarkably influenced by plant diversity and soil properties. Notably, tree species richness (TSR) displayed a significant and direct correlation to the composition and diversity of both bacterial and fungal communities. The carbon-to-nitrogen (C:N) ratio had a direct impact on the bacterial community composition and diversity, and pH had a marked impact on the fungal community composition and diversity. Furthermore, succession stage and plant diversity indirectly impacted the composition and diversity of soil bacterial and fungal communities via soil properties. Overall, it can be concluded that soil intrinsic properties and plant diversity might jointly drive the changes in soil microbial community composition and diversity during secondary succession of subtropical coniferous forests. Full article

Dalbergia hupeana Hance (D. hupeana) is a precious hardwood tree of the genus Dalbergia. It is one of the few species widely distributed within subtropical areas and is important for timber production and forest restoration. At present, there is little published genetic information on D. hupeana. Therefore, we performed a genome survey using next generation sequencing (NGS) and developed a set of novel genomic SSR (gSSR) markers from the assembled data, and assessed the transferability of these markers to other Dalbergia species in Asia. The results of the genome survey show the genome size of D. hupeana to be about 664 Mb and highly heterozygous. The assembly of sequencing data produced 2,431,997 contigs, and the initial assembly of the NGS data alone resulted in contig N50 of 393 kb with a total of 720 Mb. A total of 127,742 perfect SSR markers were found in the assembled contigs. A total of 37 highly polymorphic and easily genotyped gSSR markers were developed in D. hupeana, while the majority of gSSR markers could be successfully transferred to nine other Dalbergia species in Asia. The transferability rate of gSSR markers was highest in D. balansae, which is more closely related to D. hupeana. Seven gSSR markers were able to be amplified in all tested species. In addition, a preliminary assessment of the genetic diversity of three tree species in the Dalbergia genus suggested a high level of genetic diversity within populations distributed in the subtropical area in China. However, the determination of the global status of their genetic variation still requires further and more comprehensive assessment. Our findings will enable further studies on the genetic diversity, phylogenetics, germplasm characterization, and taxonomy of various Dalbergia species. Full article

Humid tropical forests are commonly characterized as N-rich but P-deficient. Increased N deposition may drive N saturation and aggravate P limitation in tropical forests. Thus, P addition is proposed to mitigate the negative effects of N deposition by stimulating N cycling. However, little is known regarding the effect of altered N and P supply on the nutrient status of understory plants in tropical forests, which is critical for predicting the consequences of disturbed nutrient cycles. We assessed the responses of N concentration, P concentration, and N:P ratios of seven understory species to N and P addition in an 8-year fertilization experiment in a primary forest in south China. The results showed that N addition had no effect on plant N concentration, P concentration, and N:P ratios for most species. In contrast, P addition significantly increased P concentration, and decreased N:P ratios but had no effect on plant N concentration. The magnitude of P concentration responses to P addition largely depended on the types of organs and species. The increased P was more concentrated in the fine roots and branches than in the leaves. The gymnospermous liana Gnetum montanum Markgr. had particularly lower foliar N: P (~9.8) and was much more responsive to P addition than the other species studied. These results indicate that most plants are saturated in N but have great potential to restore P in primary tropical forests. N deposition does not necessarily aggravate plant P deficiency, and P addition does not increase the retention of deposited N by increasing the N concentration. In the long term, P inputs may alter the community composition in tropical forests owing to species-specific responses. Full article

Understanding the impacts of nitrogen (N) addition on soil respiration (R_S) and its temperature sensitivity (Q₁₀) in tropical forests is very important for the global carbon cycle in a changing environment. Here, we investigated how R_S respond to N addition in a tropical montane rainforest in Southern China. Four levels of N treatments (0, 25, 50, and 100 kg N ha⁻¹ a⁻¹ as control (CK), low N (N25), moderate N (N50), and high N (N100), respectively) were established in September 2010. Based on a static chamber-gas chromatography method, R_S was measured from January 2015 to December 2018. R_S exhibited significant seasonal variability, with low R_S rates appeared in the dry season and high rates appeared in the wet season regardless of treatment. R_S was significantly related to the measured soil temperature and moisture. Our results showed that soil R_S increased after N additions, the mean annual R_S was 7% higher in N25 plots, 8% higher in N50 plots, and 11% higher in N100 plots than that in the CK plots. However, the overall impacts of N additions on R_S were statistically insignificant. For the entire study period, the CK, N25, N50, and N100 treatments yielded Q₁₀ values of 2.27, 3.45, 4.11, and 2.94, respectively. N addition increased the temperature sensitivity (Q₁₀) of R_S. Our results suggest that increasing atmospheric N deposition may have a large impact on the stimulation of soil CO₂ emissions from tropical rainforests in China. Full article

Beech (Fagus orientalis Lipsky) forests in Iran are one of the most important sources of the hardwood species used for lumber, furniture, and interior object design due to its hardness, wear resistance, strength, and excellent bending capabilities. Furthermore, Iran is third most important country for walnut wood production after China and United States. Therefore, in this study, we compared specific mechanical properties between beech wood obtained from Sangdeh (Iran) and Georgia and four different kinds of walnut woods in Iran. Physical and mechanical tests were performed according to ISO 3129 (2012) and ASTM (D143-14) standards. The moisture content of all samples was 12% during mechanical tests. The mean dry density of Sangdeh and Georgian beech obtained was 0.61 and 0.65 g/cm³, respectively, while the mean dry density of Noor, Shahrekord, Mashhad, and Mako walnut woods measured 0.62, 0.59, 0.62, and 0.57 g/cm³, respectively. The results showed significant differences among the properties of the Sangdeh and Georgian species and the four different walnut tree woods. Overall, the obtained strengths of Georgian timber were higher than that of the Iranian beech, which was attributed to the higher density of Georgian timber. Furthermore, due to the higher density of the walnut species in the Noor and Mashhad regions, the measured mechanical strengths of these trees were higher than those of other walnut species. The obtained results provide relevant information to determinate the future applications of each wood source. Full article

To identify general patterns in the effect of climate-driven changes in the outbreak frequency of forest defoliating species, we examined 60 years of records (1950–2010) of outbreaks of five defoliating species. Data on Lymantria dispar, Lymantria monacha, Bupalus piniarius, Panolis flammea, and Operophtera brumata from five Central European countries (Slovakia, Czech Republic, Austria, Hungary, and Germany), where the current climate is comparable with the projections of climate for the Eastern Baltic region by the end of the 21st century, were analyzed. Time series approach was applied to estimate the linkage between outbreaks and climate warming. Mean annual, summer, and winter deviations for the period of 1850 to 1900 were assessed as proxies of warming. To estimate the legacy effect, warming proxies were lagged by one year. Among those tested, warming proxies showed a linkage with outbreaks. Three significant outbreaks occurred in the analyzed period (at the beginning and end of the period). During the middle part of the analyzed period, the frequency and magnitude of outbreaks were low, implicating a higher insect outbreak risk with warming in Central Europe. In the latter part of the analyzed period, more frequent yet smaller outbreaks occurred, which supports the outbreak linkage with one-year lag, summer, and annual temperatures. Full article

Bark beetle (Dendroctonus spp.) outbreaks in the middle latitudes of western North America cause large amounts of tree mortality, outstripping wildfire by an order of magnitude. While temperatures play an important, and direct role in the population dynamics of ectothermic bark beetles, an equally important influence is the nature of the host substrate—the structure and composition of forested communities. For many of the dominant tree species in the western United States, “hazard” indices have been developed for specific bark beetles, which generally include three key variables—host tree size, absolute or relative density of the stand, and percentage of host composition. We provide a conceptual model to apply these three variables across forest ecosystems and bark beetles that shifts the thinking from a species–specific model to a model which focuses on the underlying ecological factors related to bark beetle outbreak susceptibility. We explored the use of our model across multiple scales using the Forest Inventory and Analysis database: Interior West, USA; the states of Colorado and Arizona; and specific national forests within Arizona that are implementing a large-scale restoration effort. We demonstrated that across the Interior West and Colorado, the vast majority of forests have moderate to high susceptibility to bark beetles. Our conceptual model maintains the simplicity of previous “hazard” models but acknowledges the need to consider scale when managing bark beetles. It also shifts the management approach from resistance thinking to the development of “associational resilience”, where the focus is not on any one individual stand or area but the longer-term perspective of forest persistence across the landscape. Full article

Skidding is considered to be one of the most stressful works for the forest environment. This paper presented the results obtained from the analysis of soil deformation and selected physical and mechanical parameters of soils on skid trails in the Gorce National Park. The study analyzed two horse and tractor skid trails that are in continuous use in the park. Measurements of parameters were recorded before (summer) and after (autumn) a total of 81 skidding cycles, using a profilometer and a penetrometer, and soil samples were collected for analysis. The measurements obtained from the horse trails indicated that soil compactness was considerably higher in the lower sections of the trails and on the side more loaded by horse traffic and the transported load, which was related to the trail course in the field. The values of penetration resistance were high in the middle of those trails, reaching 6.8 MPa in the layer up to 10 cm. In the tractor trail the values of soil compactness reached 7.62 MPa in the layer up to 10 cm deep and were similar across the width of the trail and deep into the soil profile, with only slight changes observed in the monitored period. As a result of skidding, there were increases in the maximum depth of ruts reaching up to 4.6% on horse trails and up to 10.8% on tractor trails. Soil erosion per 10 m of trail caused by skidding and other natural factors during the study reached 1.314 and 0.390 m³ for the tractor and horse trail, respectively, wherein volume of skidded wood on the tractor trail was 180.1, and 18.1 m³ on horse trails. This confirms that the volume of eroded soil on the trails is determined by the type of skidder used and volume of skidded wood, so it is important to choose the right kind of skidder based on the conditions in which the skidding work will be carried out. Full article

Most tree species in the temperate climatic zone (including Douglas fir) disperse seeds in autumn. Some of them must be exposed to cold (0–10 °C) and moist conditions (cold stratification) to overcome dormancy and trigger germination. In the Northern Hemisphere, winter warm spells occur more frequently and last longer than in recent decades from eastern Canada to Europe. Our main research objective was to investigate the influence of current (1 or 3 days at day/night temperatures: 15 °C/10 °C) and future predicted (5 days at day/night temperatures: 25 °C/15 °C) winter warm spells on dormancy breaking and germination traits (germination energy—GE; germination capacity—GC; final germination capacity—FGC) of Douglas fir seeds from four old-growth stands in northern Poland. For this purpose, we interrupted cold stratification of seeds at different time points, i.e., after 3 weeks; 6 weeks; 9 or 3 weeks and 6 weeks; 3 and 9 weeks; 6 and 9 weeks; 3 and 6 weeks and 9 weeks. We found that for GE and GC, all main effects (populations—P; days of warm spell—D; stratification duration—W) and interactions were significant (except interaction P×D). FGC was significantly affected by the effects P and D and interactions of D × W and P × D × W. In addition, we found that the predicted warm spells negatively affected the early germination stage (GE and GC) of Douglas fir, but both current and future predicted winter conditions will not negatively affect the late germination stage (FGC). Full article

We investigated the effects of forest management on the carbon (C) dynamics in Romanian forest soils, using two model simulations: CBM-CFS3 and Yasso15. Default parametrization of the models and harmonized litterfall simulated by CBM provided satisfactory results when compared to observed data from National Forest Inventory (NFI). We explored a stratification approach to investigate the improvement of soil C prediction. For stratification on forest types only, the NRMSE (i.e., normalized RMSE of simulated vs. NFI) was approximately 26%, for both models; the NRMSE values reduced to 13% when stratification was done based on climate only. Assuming the continuation of the current forest management practices for a period of 50 years, both models simulated a very small C sink during simulation period (0.05 MgC ha⁻¹ yr⁻¹). Yet, a change towards extensive forest management practices would yield a constant, minor accumulation of soil C, while more intensive practices would yield a constant, minor loss of soil C. For the maximum wood supply scenario (entire volume increment is removed by silvicultural interventions during the simulated period) Yasso15 resulted in larger emissions (−0.3 MgC ha⁻¹ yr⁻¹) than CBM (−0.1 MgC ha⁻¹ yr⁻¹). Under ‘no interventions’ scenario, both models simulated a stable accumulation of C which was, nevertheless, larger in Yasso15 (0.35 MgC ha⁻¹ yr⁻¹) compared to CBM-CSF (0.18 MgC ha⁻¹ yr⁻¹). The simulation of C stock change showed a strong “start-up” effect during the first decade of the simulation, for both models, explained by the difference in litterfall applied to each scenario compared to the spinoff scenario. Stratification at regional scale based on climate and forest types, represented a reasonable spatial stratification, that improved the prediction of soil C stock and stock change. Full article

Chestnut blight, a disease that has spread rampantly among American (Castanea dentata (Marsh.) Borkh.) and European chestnut (C. sativa Mill.) trees, results from infection by the fungal pathogen Cryphonectria parasitica (Murrill) M.E. Barr (C. parasitica). This fungus was introduced in the early 1900s and has almost functionally eliminated chestnut trees from the North American landscape. In 2017, we collected chestnut blight samples from two sites (Site B, (Fulton Co., IN) and Site C (Marshall Co., IN)). At the Fulton County planting, Site B, cankers had formed, healed over, and the trees were healthy. However, at the second site in Marshall County, (Site C), cankers continued to propagate until all of the chestnut trees had died back to the ground. Research evidence worldwide has indicated that these visual clues likely result from the presence of a hypovirus. Upon closer inspection and the subsequent isolation and reproduction of spores, no hypovirus has been identified from either site. Here, we present a curious coincidence where one site has completely succumbed to the disease, while the other has been able to spring back to health. Full article

Functional characteristics reflect plant strategies and adaptability to the changing environment. Determining the dynamics of these characteristics after harvesting would improve the understanding of forest response strategies. Strip clearcutting (SC) of moso bamboo forests, which significantly reduces the cutting cost, has been proposed to replace manual selective harvesting. A comparison of restoration features shows that 8 m is the optimal cutting width. However, the precise response of functional features to the resulting harvest-created gap remains unclear. In this study, three SC plots were selected which was performed in February 2019, with three unharvested plots as a control (C). The study focused on 10 functional traits, including leaf area (LA), specific leaf area (SLA), leaf dry matter content (LDMC), leaf nitrogen content (LNC), leaf phosphorus content (LPC), nitrogen/phosphorus ratio (N:P), wood density (WD), fine root biomass (FRB), specific fine root length (SRL), and root length density (RLD). A one-way ANOVA was used to compare differences in functional traits and soil nutrients between treatments. Strip clearcutting significantly reduced the soil organic carbon (SOC) and total nitrogen (TN) contents (p < 0.05). In terms of functional characteristics, SC significantly decreased LA and increased LNC, LPC, and N:P (p < 0.05). However, SC had no significant effect on fine root traits (p > 0.05). This study highlighted that root trait, soil content of total phosphorus (TP) and total potassium (TK) returned to the level of uncut plots after a year’s recovery. The LPC, LNC, and N:P were negatively correlated with LA, and LDMC and WD were negatively correlated with SLA, while the effect of SC on fine root traits was limited (p > 0.05). Fine root traits (FRB, RLD, and SRL) were positively associated with SOC, TN, and TP, but negatively correlated with TK. The changes in soil nutrient content caused by the removal of biomass were normal. Increased light and the rapid growth of new trees will increase nutrient regressions; therefore, these results further confirm the feasibility of SC. Full article

The Chinese Loess Plateau (CLP) is known for its complex topography of hills and gullies, and lots of human land-use management activities have been put into practice to sustain the soil, water and other natural resources. Afforestation has been widely applied on the CLP and it’s important to understand the effects of topography on these planted trees. However, the coarse spatial resolution of remote sensing data makes it insensitive to local topography, and the traditional in-situ measurements would consume vast amounts of time and resources. In this study, a small headwater catchment of the CLP was selected to study the effects of topography on the planted trees. Low altitude unmanned aerial vehicle based light detection and ranging (UAV-based LiDAR) technology was utilized to obtain high-resolution topography and vegetation structure data. Results showed that the middle transition zone (mid-transition, slope > 45°) was an important boundary of topography in the gully area of the CLP. In the forested catchment, the area of the mid-transition zone had the lowest of tree density, canopy coverage and leaf area index due to steep slope gradient. The tall trees ten to twenty meters high were concentrated in the downhill area, which had the highest canopy coverage and leaf area index. Elevation had significant linear relationships with canopy coverage and leaf area index (p < 0.001), which revealed the impact of topography on the forest indexes of the afforestation catchment. We concluded that the high-resolution LiDAR technology facilitated the research of topography and forest interactions in land surface. Full article

Intensive silviculture is practiced in many parts of the world but is rare in the public forests of western Canada. Here, we make the argument that intensive silviculture could be justified in Alberta but has not been implemented due to philosophies and policy decisions by foresters from government, industry and academia. These include adherence to long rotations, management goals that are aimed at sustained total volume yield rather than economic value, limitations in the types of stands that are allowed to be regenerated and models that do not include intensive silviculture options. In Mixedwood Growth Model projections, we demonstrate the potential of intensive silviculture that includes combinations of selecting good sites and thinning to produce merchantable stands by age 50 compared to the standard rotation age of 80 with basic silviculture. There could be even more gains if forest level constraints in timber flow were removed due to the increased growth of regenerating stands. Finally, we examine the attitude and policy changes that we believe are necessary for adoption of more intensive silviculture systems on parts of Alberta’s forest landbase. Full article

WRKY transcription factors are one of the largest families in plants, playing important roles in regulating plant immunity. Malus sievesii has abundant genetic diversity and can offer various and high-quality gene resources. In this study, 112 putative MsWRKY proteins were identified from a full-length transcriptome of M. sieversii during the Valsa canker disease (caused by Valsa mali). The MsWRKY proteins were phylogenetically divided into three groups (I–III). Motif compositions of the MsWRKY proteins were clustered and fifteen conserved motifs were observed. Expression pattern analysis showed that thirty-four MsWRKY transcripts strongly responded to the V. mali infection, demonstrating that MsWRKY transcripts might play different roles during the response. Functional identifications were subsequently conducted with transient expressions, demonstrating that MsWRKY16, MsWRKY21, MsWRKY70, MsWRKY74 and MsWRKY85 positively regulated the resistant response. Besides, the MsWRKY21, MsWRKY70 and MsWRKY85 were dramatically induced by salicylic acid (SA), methyl-jasmonate acid (MeJA) and 1-aminocyclopropane-1-carboxylate (ACC), indicating that they play important roles in the regulatory resistance of V. mali infection. This work provides a comprehensive understanding of the WRKY family in M. sieversii and will build a foundation for future research of the potential disease resistances MsWRKY transcripts. Full article

The process of etiolation contributes significantly to vegetative propagation and root formation of woody plants. However, the molecular interaction pattern of different factors for etiolated adventitious root development in woody plants remains unclear. In the present study, we explored the changes at different etiolation stages of adventitious root formation in Robinia pseudoacacia. Histological and transcriptomic analyses were performed for the etiolated lower portion of hypocotyls to ascertain the adventitious root responses. We found that the dark-treated hypocotyls formed roots earlier than the control. Exogenous application of NAA (0.3 mg/L) stimulated the expressions of about 310 genes. Among these, 155 were upregulated and 155 were downregulated. Moreover, differentially expressed genes (DEGs) were significantly enriched in multiple pathways, including the biosynthesis of secondary metabolites, metabolic pathway, plant hormone signal transduction, starch and sucrose metabolism, phenylpropanoid biosynthesis, and carbon metabolism. These pathways could play a significant role during adventitious root formation in etiolated hypocotyls. The findings of this study can provide novel insights and a foundation for further studies to elucidate the connection between etiolation and adventitious root formation in woody plants. Full article

In arid and semi-arid regions, a better understanding of the effect of climate change mechanisms on environmental evolution can be used to guide regional ecological conservation and to improve water resource availability. Increased aridity in arid and semi-arid regions considerably affects the physiological functions of plants and the exchange of carbon and water with the environment. We collected Pinus tabuliformis Carr. samples from Ordos, Inner Mongolia, and measured their δ¹⁸O variations. Vapour pressure (VP) was the main factor dominating δ¹⁸O variations from July to August, indicating the regulatory role of plant leaf stomata. Based on the δ¹⁸O series in the Ordos region, we reconstructed VP variations for July–August (VP_JA) for the past 205 years. Spatial analysis showed the reconstruction as spatially highly representative. VP variations in the Ordos region mainly reflected precipitation variations and did not show a significant correlation with temperature. Since the late 1950s, VP has been decreasing, which is related to the weakening of the Asian monsoon. The results of reconstruction decomposed using ensemble empirical mode decomposition showed that El Niño–Southern Oscillation may affect VP in the study area, and the effect of sea surface temperature on the central and eastern Pacific Ocean in the Ordos region may lead to an increase in the drought. Full article

Afforestation is an effective solution for restoring forest ecosystems and mitigating climate change in the tropics. In this study, we analyzed the soil respiration (Rs) at four afforested sites with different tree species exposed to a monsoon climate with frequent typhoon occurrences in southern Taiwan. The aim of this study is to examine (1) the distinct seasonal variation that strongly affects the Rs among four tree species at afforested sites, (2) the patterns of Rs that differ among the four species at the afforested sites, and (3) the influence of typhoons on forest structure and consequently the degree of Rs. The annual mean Rs among the four tree species at the afforested sites in the pretyphoon disturbance year was approximately 7.65 t C ha⁻¹, with the post-typhoon year having an annual mean Rs of approximately 9.13 t C ha⁻¹. Our results clearly show Rs variations in the four tree species at the young afforested sites under the influence of typhoon disturbances. The high seasonal variations in Rs were controlled by soil temperature and soil moisture. The different tree species also led to variations in litterfall production and consequently influenced Rs variation. Forest structures, such as aboveground biomass and consequently the degree of Rs, were disturbed by severe typhoon impacts in 2016, resulting in high aboveground biomass with tree height losses and litterfall accumulation. Furthermore, Rs increased immediately after litterfall input to the soil, and the addition effect of litter and the soil C release occurred throughout the year after typhoon disturbances. Our results contribute to understanding impact of typhoon disturbances on the degree of Rs at tropical afforested sites. Full article

The oak flora of North America north of Mexico is both phylogenetically diverse and species-rich, including 92 species placed in five sections of subgenus Quercus, the oak clade centered on the Americas. Despite phylogenetic and taxonomic progress on the genus over the past 45 years, classification of species at the subsectional level remains unchanged since the early treatments by WL Trelease, AA Camus, and CH Muller. In recent work, we used a RAD-seq based phylogeny including 250 species sampled from throughout the Americas and Eurasia to reconstruct the timing and biogeography of the North American oak radiation. This work demonstrates that the North American oak flora comprises mostly regional species radiations with limited phylogenetic affinities to Mexican clades, and two sister group connections to Eurasia. Using this framework, we describe the regional patterns of oak diversity within North America and formally classify 62 species into nine major North American subsections within sections Lobatae (the red oaks) and Quercus (the white oaks), the two largest sections of subgenus Quercus. We also distill emerging evolutionary and biogeographic patterns based on the impact of phylogenomic data on the systematics of multiple species complexes and instances of hybridization. Full article

(1) Background: Wood decay is a serious issue that results from the presence of wood-destroying fungi and has a great influence on the international wood industry. The utilization of biological control methods offers good prospects for wood preservation. (2) Methods: The plate-screening experiment, the soil block test of the Chinese stand method (GB/T 13942.1), and the characterization of wood blocks were used to achieve biological control of brown rot and white rot. (3) Results: Through isolation, screening, and identification, the antagonistic bacterium Bacillus velezensis Nhw-B72 strain was obtained. In the plate-screening experiment, the inhibition zone diameter of Nhw-B72 for Gloeophyllum trabeum was 1.68 cm and that for Coriolus versicolor was 2.33 cm. After inhibition, the morphology of mycelia was distorted, malformed, and broken. In the soil block test, the average weight loss percentage of wood blocks in the control group was 61.66%. In the treatment group, the average weight loss percentage of the wood blocks with drying was 28.18% and that of the wood blocks without drying was 34.97%. (4) Conclusions: The strain has an obvious antagonistic effect on the wood-destroying fungi and the sterile fermentative liquid can effectively inhibit wood decay. In addition, compared to the drying of wood blocks, the air-drying of blocks after impregnation with the fermentative liquid had a better inhibition effect. Full article