Cold climate viticulture is challenged by climatic variability, including increased frost risk, shorter growing seasons, and unpredictable weather events that impact vine productivity and grape quality. Global warming is altering traditional viticulture zones, prompting the exploration of new regions for grape cultivation, the selection of climate-resilient cultivars, and the implementation of adaptive practices. This review synthesizes recent advances in adaptive viticulture practices and plant growth regulator applications, highlighting novel molecular and physiological insights on cold stress resilience and berry quality. Key strategies include delayed winter pruning to mitigate frost damage, osmoprotectant application to improve freeze tolerance, and canopy management techniques (cluster thinning and defoliation) to enhance berry ripening and wine composition. Their effectiveness depends on vineyard microclimate, soil properties and variety-specific physiological response. Cover cropping is examined for its role in vine vigor regulation, improving soil microbial diversity, and water retention, though its effectiveness depends on soil type, participation patterns, and vineyard management practices. Recent transcriptomic and metabolomic studies have provided new regulatory mechanisms in cold stress adaptation, highlighting the regulatory roles of abscisic acid, brassinosteroids, ethylene, and salicylic acid in dormancy induction, oxidative stress response, and osmotic regulation. Reflective mulch technologies are currently examined for their ability to enhance light interception, modulating secondary metabolite accumulation, improving technological maturity (soluble solids, pH, and titratable acidity) and enhancing phenolic compounds content. The effectiveness of these strategies remains highly site-specific, influenced by variety selection and pruning methods particularly due to their differences on sugar accumulation and berry weight. Future research should prioritize long-term vineyard trials to refine these adaptive strategies, integrate genetic and transcriptomic insights into breeding programs to improve cold hardiness, and develop precision viticulture tools tailored to cold climate vineyard management.
Pre-commercial thinning has potential to mitigate the effect of drought stress on growth but likely removes protection from environmental temperature extremes. Processes driving growth after density management are poorly understood but important when applying thinning to stands that will grow under future warmer and drier conditions. Consequently, we evaluated microclimate and resource availability in operational scale pre-commercial thinning trials (treated and control) of young (19-year-old) boreal trembling aspen/white spruce mixedwoods in northern Alberta, Canada. Thinned stands in this study experienced more temperature extremes, both 30 degrees C, than unthinned stands as well as the same quantity of extreme low soil moisture values. However, lower tree density in thinned stands provided more available heat and higher average soil moisture, especially during dry periods in the year. Soil nutrient supply rates were not different between treatments, nor was soil moisture during wet periods, nor was soil temperature in the early and late parts of the growing season. Regeneration of broadleaf trees species in thinned stands was substantial. Overall, pre-commercial thinning caused both positive and negative changes to the tree-growing environment.
Crowns of trees neighboring a strip road are exposed to greater amounts of sunlight, which may result in the so-called edge effect, leading to enhanced tree growth. The aim of this study was to assess the edge effect after twenty years since the clearing of strip roads in terms of diameter at breast height (DBH), tree height, crown base height, and crown length. Based on the results of earlier measurements, temporal changes in tree diameters at strip roads were also evaluated. The analyses were conducted in a pine stand, where strip roads 3.5 m or 2.5 m wide had been cleared at a stand age of 31 years, and after eight years the width of the narrow strip roads had been increased to 3.5 m. Measurements were taken on trees growing immediately adjacent to strip roads (edge trees) and those approximately 4.5 m from the road axis, as well as those in the middle of the distance between neighboring strip roads (as a reference). Trees growing at the edge of strip roads had statistically significantly larger diameters at breast height than trees growing farther from strip roads. The differences in tree height were slight and statistically non-significant, whereas the crowns of trees growing at the edges of strip roads had lower bases and were longer than the crowns of other trees. Analysis of DBH data recorded from measurements over 20 years showed a gradual reduction in the effect of strip roads on the diameters of trees growing at their edges.
Intensive forest management has promoted an increase in deer (Cervidae) population density. Various silvicultural activities, such as pre-commercial thinning, can change the feeding conditions for deer species, therefore impacting browsing pressure on target tree species. In this study, we analyzed how several factors, including the density of the main tree species, admixture, undergrowth, and forest type, affect deer damage intensity in pine stands, considering deer densities and regional aspects in hemiboreal Latvia. GLMM analysis, based on data from 1238 sample plots, showed that the probability of browsing damage decreases with an increase in the density of undergrowth in young (<20 years) pine stands with a dominant height below 3 m. Also, the probability of pines being damaged by deer was significantly (p = 0.001) higher in stands with fresh pre-commercial thinning than in those with no thinning. However, differences in deer density between regions also determined browsing pressure. Results indicated that undergrowth density, pre-commercial thinning, and deer density may be important drivers of damage levels, especially in the winter browsing of young pine stands on wet mineral soils. Therefore, future research should continue to evaluate applied forest management strategies in hemiboreal forests that provide additional natural food base in the form of woody plants and shrubs in winter forage to ensure more deer-adapted practices.
Flow-like events usually occur during heavy rainfall and pose significant threats to ecosystems and human life and property because of their suddenness, high speed, and long distances. To study the solid-fluid transition and subsequent high fluidity and hypermobility mechanism of redeposited loess, we conducted a series of flume tests and rheological tests, and the results showed that loess exhibits different degrees of fluidized movement characteristics under different rainfall intensities, and a rainfall intensity of 90 mm/h was the most likely to trigger loess flowslides. Additional rheological analyses indicated that viscosity (shear rate) bifurcation characterizes the rheological response of loess solid-fluid transition, and the decrease in viscosity caused by shear thinning can explain the drag reduction effect and its high fluidity in the process of solid-fluid transition, which corresponds well with the results of flume tests. We proposed a two-step yielding characteristic and introduced structural dynamics to establish a unified solid-fluid transition model incorporating a hydro-mechanical coupling and rheological property. The model can be used to describe both the solid-like behavior of soil before phase transition using an elastoplastic model and fluid-like behavior after phase transition using a viscoplastic model. The research results provide a new understanding of solid-fluid phase transition characteristics of loess from the perspective of rheology, which can also provide a new idea for studying the fluidization movement of rock avalanches and pyroclastic flows and their geomorphic evolution.
Pathogen-caused stem and root decay are becoming increasingly common in Norway spruce (Picea abies (L.) H. Karst) which is believed to contribute to greater stand instability and susceptibility to wind-inflicted damage. Thus, this study aims to assess the effect of root and stem decay on Norway spruce vulnerability to wind-inflicted mortality in monospecific and mixed stands, to widen our base of knowledge on potentially more resilient spruce forest management approaches in hemiboreal forest zone. In this study we used data from: i) the National Forest inventory (NFI), ii) 34 observation plots established in wind-affected stands, iii) two transects (9200 m long, 36.8 ha inspection area combined), iv) and monospecific spruce plantation thinning experiment (five thinning intensities with two repetitions of each) affected by wind. We found that the total mortality of spruce during the NFI four five-year re-measurement cycles (2003-2007, 2008-2012, 2013-2017, 2018-2022) was 2.28%, during which the main disturbance-causing agents were wind at 0.86 %, pests at 0.41 %, intra/interspecific competition at 0.37 %, and diseases at 0.36 %. NFI data-based multinomial logistic regression model revealed that the probability of wind-inflicted spruce mortality is dictated by soil moisture regime, stand age, stand stocking level, and tree decay presence. Results from the 34 established observation plots show that wood decay is a potential risk factor associated with wind damage occurrence in spruce stands. In a spruce stand, when a group of trees are damaged by wind the proportion of undecayed trees increases. Whereas a single tree is more likely to be attributed to decay caused wind damage.Results point towards deciduous broadleaf admixture having a positive effect on mitigating wind damage among non-decayed spruce trees: however, decayed trees, are more likely to be affected in such stands. The thinning experiment portion of this study suggests that increasingly intensive thinning in monospecific spruce stands will lead to an increasing spread of root and stem decay and thus the risk of wind damage. Therefore, from this perspective, the main goal is to reduce the root and stem decay presence in the stand and thus increase wind stability. We suggest further research to be directed into finding the optimal initial spruce seedlings density with a combination of coniferous and deciduous broadleaf species in order to mitigate root and stem decay presence and wind-inflicted spruce mortality in the forest stands.
Application of biopolymers to improve the mechanical properties of soils has been extensively reported. However, a comprehensive understanding of various engineering applications is necessary to enhance their effectiveness. While numerous experimental studies have investigated the use of biopolymers as injection materials, a detailed understanding of their injection behavior in soil through numerical analyses is lacking. This study aimed to address this gap by employing pore network modeling techniques to analyze the injection characteristics of biopolymer solutions in soil. A pore network was constructed from computed tomography images of Ottawa 20-30 sand. Fluid flow simulations incorporated power-law parameters and governing equations to account for the viscosity characteristics of biopolymers. Agar gum was selected as the biopolymer for analysis, and its injection characteristics were evaluated in terms of concentration and pore-size distribution. Results indicate that the viscosity properties of biopolymer solutions significantly influence the injection characteristics, particularly concerning concentration and injection pressure. Furthermore, notable trends in injection characteristics were observed based on pore size and distribution. Importantly, in contrast to previous studies, meaningful correlations were established between the viscosity of the injected fluid, injection pressure, and injection distance. Thus, this study introduces a novel methodology for integrating pore network construction and fluid flow characteristics into biopolymer injections, with potential applications in optimizing field injections such as permeation grouting.
The phyllosphere is an important but underestimated habitat for a variety of microorganisms, with limited knowledge about leaf endophytes as a crucial component of the phyllosphere microbiome. In this study, we investigated the mechanisms of communities and co-occurrence networks of leaf endophytes in response to forest thinning in a temperate forest. As we expected, contrasting responses of fungal and bacterial endophytes were observed. Specifically, the diversity of leaf endophytic fungi and the complexity of their co-occurrence networks increased significantly with thinning intensity, whereas the complexity of endophytic bacterial co-occurrence networks decreased. In particular, microbiota inhabiting damaged leaves seem to be more intensively interacting, showing an evident fungi-bacteria trade-off under forest thinning. In damaged leaves, besides the direct effects of thinning, thinning-induced changes in neighbor tree diversity indirectly altered the diversity of leaf fungal and bacterial endophytes via modifying leaf functional traits such as leaf dry matter content and specific leaf area. These findings provide new experimental evidence for the trade-offs between leaf endophytic fungi and bacteria under the different magnitudes of deforestation, highlighting their dependence on the presence or absence of leaf damage.
To enhance crop yields, narrowing the gap between actual and achievable yields is crucial. One approach involves identifying yield-limiting factors and their optimal levels. Boundary line analysis (BLA), a statistical method, quantifies yield response to environmental or managerial factors while accounting for variable factors. In 2020, a study surveyed 180 spring sugar beet farms in Iran. The findings revealed a 50.7 % yield gap (11.13 t ha -1 ) between farmers' average sugar yield (10.84 t ha -1 ) and potential yield (21.97 t ha -1 ). BLA implicated low plant density, soil organic content, lack of potassium (K)-containing fertilizers, and non-adherence to crop rotation principles in 81.3 %, 75.5 %, 53.4 %, and 51.1 % of farms, respectively. Optimal levels were estimated at 9.5 plants m -1 , 1.15 % soil organic content, 100 kg ha -1 K fertilization rate, and 5-9.8 as the rotation numerical value. Other limiting factors included time from cultivation to thinning and sowing date. The optimal minimum time between planting and thinning stood at 38 days, with the latest sowing date estimated at 94 Julian days (May 5). Achieving attainable yield necessitates limiting root exposure to 4.9 days, keeping disease damage below 15.3 %, and increasing irrigation frequency to over 10 times. In the short term, increasing plant density to optimal levels, promoting K fertilizer use, and adjusting thinning and sowing dates can significantly boost sugar yield per unit area.
Forest degradation, driven by human and natural factors, diminishes ecological functions and carbon storage. Understanding the complex dynamics of soil carbon pools is crucial for the global carbon cycle, although these dynamics are poorly understood. This study examines how different thinning intensities influence seasonal soil carbon cycling in degraded forests. ANOVA revealed significant differences in soil properties across treatments (p < 0.05). Redundancy analysis and random forest analyses were used to explore relationships among thinning intensities, soil properties, and carbon sequestration. Thinning significantly altered soil attributes, as revealed by field experiments and data analysis. Moderate thinning (20% intensity) significantly enhanced litter retention and soil nutrient levels year-round (p < 0.05). Seasonal variations affected soil carbon dynamics and lower thinning intensities improved carbon sequestration in spring and summer. Conversely, higher thinning intensities led to carbon loss in autumn and winter. Litter carbon, fine root carbon, and correction factor significantly respond to thinning intensities year-round as examined through redundancy analysis and random forest analyses. Findings indicate moderate thinning effectively enhances soil carbon sequestration in degraded forests. Strategically planned thinning could aid climate change mitigation by boosting forest soil carbon storage, influencing forest management and conservation.