Thinning Treatments Research Articles

Multivariate mixed-effects models for stand characteristics of hybrid aspen plantations in southern Finland and southern Sweden

Hybrid aspen, a hybrid between the European aspen and North American trembling aspen (Populus tremula L. × P. tremuloides Michx.), is a promising species because of its fast-growth and its suitability for multi-purpose use. However, models for predicting the age-dependent development of stand characteristics are still missing. The main objectives of this study were therefore to develop the models for predicting stand characteristics of hybrid aspen plantations and to validate the model applicability. The target response variables were stand basal area (BA), basal area-weighted mean diameter (DG) and basal area-weighted mean height (HG). Data were obtained from clonal hybrid aspen trials in southern Finland and southern Sweden. Multivariate mixed-effects modelling was used to estimate the parameters of seemingly unrelated regression for BA, DG, and HG. Model fit provided the following predictor variables: stand age (AGE), the number of trees per hectare (TPH), site index (SI), growing degree-days (GDD5), soil and site type, and thinning treatment. The chosen predictors differed slightly by response variable, but all parameters were highly significant (P < 0.0001), and model goodness-of-fit statistics presented high accuracy: RMSE of 2.59 m2 ha−1 for BA, 1.21 cm for DG, 1.05 m for HG in arithmetic scale. The applied simulations illustrated clear differences in the predicted development of stand characteristics when input variables SI, TPH or GDD5 changed. The developed models were assessed to be easily applicable and useful for predicting the stand and tree characteristics of clonal hybrid aspen plantations, especially for the stands with AGE ≤ 30 years and TPH ≤ 2000 trees ha−1.

Determination of Recent In-Migrants in Yogyakarta using Bayesian Regression Logistics

Aims: This research aims to find out the status determinant of recent in-migrants entering the province of Yogyakarta, Indonesia in 2021 with Bayesian logistic regression combined with a nonlinear principal component analysis in the process of forming a latent variable.&#x0D; Study Design: Quantitative Design.&#x0D; Place and Duration of Study: This research was carried out in the city of Yogyakarta with the data used is 1 year data throughout 2021.&#x0D; Methodology: The data were obtained from the results of national socio-economic surveys (SUSENAS) KOR in March 2021.&#x0D; Results: The research results indicate that particular variables such as age, resident latest education, the status of main activities, the status of residential ownership, housing quality, and asset ownership have significant influences on recent in-migrants entering the Province of Yogyakarta, Indonesia.&#x0D; Conclusion: This research concludes that the Bayesian approach in logistic regression with iteration 1,000,000, 4 thinning interval, and 500.000 burn-in indicates that of seven variables, six variables with significant influences on the status of recent migrants entering the Province of Yogyakarta consist of age (X1), latest education (X3), main activities (X4), house ownership (X5), housing quality (X6), and asset ownership (X7). Of these six variables, the younger resident, the resident with high school or equal as their latest education, the resident currently working as their main activity, the resident renting a house, and the resident with high housing quality score and high asset ownership score are more likely to do recent migration to the Province of Yogyakarta.

Semi-wet methanogen cathode composed of oak white charcoal for developing sustainable microbial fuel cells

The present study aimed to evaluate a semi-wet biocathode composed of oak white charcoal and agarose gel as an alternative to the standard carbon felt biocathodes used in microbial fuel cells (MFCs). The MFC containing the oak white charcoal cathode (Oak-MFC) recorded a higher current value than that of the MFC containing a carbon felt cathode (CF-MFC). The Oak-MFC produced approximately 4.0-fold more electrons in the external circuit and 1.7-fold more methane (CH4) than the CF-MFC. A real-time PCR targeting mcrA showed that the number of methanogens adhering to the oak white charcoal cathode was approximately 15-fold that adhering to the carbon felt cathode. These results suggest that the methanogens attached to the cathode of both MFCs received electrons and CH4 was produced from carbon dioxide (CO2). Furthermore, Oak-MFC performed better than CF-MFC, thereby suggesting that oak white charcoal bound by agarose gel can be used as an alternative methanogen cathode. The propionic acid degradation rate of Oak-MFC was faster than that of CF-MFC suggesting that the cathodic reaction may affect the anodic reaction. The use of oak-derived electrode as a methanogen cathode also could contribute to sustainable forest management and promote regular thinning of oak trees. Further, its use will enable carbon fixation and efficient energy conversion from CO2 to CH4, thus contributing to sustainable energy use.

Source–Sink manipulations have major implications for grapevine berry and wine flavonoids and aromas that go beyond the changes in berry sugar accumulation

Sugar levels in grape berries are necessary for wine production but also, they are the main driver of most ripening processes. Sugar levels are very responsive to canopy and crop load adjustments. The aim of this study is to test the effect of different levels of defoliation and cluster thinning on grape ripening and wine composition. ‘Cabernet sauvignon’ grapevines (Vitis vinifera L.) were subjected to defoliation (keeping 100 %, 66 % and 33 % of the leaves) and fruit thinning treatments (keeping 100 %, 66 % and 33 % of the clusters) combined in a factorial design. The experiment was repeated for 2 consecutive seasons (2017 and 2018) and the plants were left untreated for a third season (2019) to observe the carry-over effects of the treatments. The treatments implied precise adjustments of leaf and cluster numbers. However, the proportion of leaf area to fruit mass tended to compensate each other and interact resulting in smaller differences in leaf area or fruit mass by harvest. Berry mass was strongly reduced by defoliation even in the subsequent season where no defoliation was applied. Berry ripening indicators (soluble solids, acidity and anthocyanin levels) were also more affected by defoliation than fruit thinning. Anthocyanin profile was shifted to a higher proportion of Malvidin-derived anthocyanins for defoliated vines and lower proportion of Malvidin-derived anthocyanins in the case of thinned vines. However, when it came down to wine, the physicochemical parameters as well as the aroma profile were more affected by cluster thinning. There was a clear relationship between sugar levels of the unfermented must and many wine-aroma compounds. Green aromas (2-isobutyl-3-methoxypyrazine, hexanol and cis-3-Hexen-1-ol) were among those presenting a negative correlation to must sugar whereas other compounds like Isobutyric acid, Benzyl alcohol, 1-Octen-3-ol and γ-Nonalactone had a positive correlation. This study reveals a higher level of complexity of source sink relations where leaves and clusters do not only act as a source and a sink of carbon, respectively. Therefore, the results of this study should be considered before making comparisons of leaf area to fruit mass ratios across different vine-growing systems.

A multi‐scale assessment of forest treatment impacts on evapotranspiration and water yield in the Sierra Nevada

AbstractThe future of the Western United States is threatened by both an increase in wildfire frequency and a decrease in water availability. By reducing fuel loads, wildfire mitigation measures (forest treatments) can offer reduced fire severity and increased annual total runoff (water yield) via reduction in evapotranspiration (ET). While the benefits of forest treatments for fire management are well studied, their impact on ET and water yield remains largely unknown, and existing literature shows conflicting results. Here, we aim to resolve this ambiguity by quantifying the impact of forest treatments on ET and water yield, at spatially localized scales. Using daily average flow rates from sub‐basin and basin scale gauges, 100‐m LiDAR data, 800‐m PRISM precipitation data and 30‐m SSEBop ETa data, we analysed the impact of forest treatments on ETa and water yield in the Sagehen Experimental Watershed. Within treated areas of Sagehen, there is a linear relationship between loss of canopy cover and ETa reductions at the 100‐m pixel scale when canopy cover loss exceeds 10%. The impact of treatment was highly localized, and across the entire watershed (30 km2), treated areas with reduced ETa only made up 4 km2, ~10% of the Sagehen area. At sub‐basin and basin scale, the magnitude of year‐to‐year ETa reduction was &lt;15%, and there was no quantifiable increase in water yield. Instead, precipitation alone explained 85% of water yield variability at sub‐basin and basin scale. Future forest management practices in the Sierra Nevada are essential for combating wildfire, but our results from Sagehen reveal that even at the sub‐basin scale (~3 km2), 56% thinning treatment by area did not result in increased water yield.

Effects of thinning intensities on litterfall characteristics and decomposition in the natural secondary lowland forests of Southeastern Taiwan

ABSTRACT Research Highlights: This study presented novel evidence of the optimal level of forest thinning to maintain nutrient cycling and achieve management objectives. Background and Objectives: Litter dynamics play a vital role in balancing forest nutritional dynamics, which may be related to forest productivity. This study aimed to examine the influence of thinning intensity on litter quantity and quality in a secondary forest (a natural tropical secondary forest in southeastern Taiwan). Materials and Methods: Five different thinning treatments were implemented, and forest dynamics were measured. The litterbag method was used to assess the initial status of litter decomposition. Results: The rate of litter accumulation without thinning ranged from 5.14 to 5.63 t ha−1 yr−1. Thinning altered the litter decomposition rate. A 20% thinning intensity resulted in the fastest litter decomposition, with an annual litter loss of 22.4% compared with the control area. However, at >60% thinning intensity, the rate of litter decomposition slowed down, and the annual loss increased to 42.5%. Conclusions: Thinning changes the litter decomposition rate mainly by influencing soil humidity and temperature. A thinning intensity of 20% in secondary forest thins the forest, improves litter status, accelerates litter decomposition, and promotes nutrient cycling.

Invasive blackberry outcompetes the endemic Galapagos tree daisy Scalesia pedunculata.

Island florae are under threat from habitat loss and competition with introduced species worldwide. In the Galapagos Islands, the endemic tree daisy Scalesia pedunculata (Asteraceae) is the dominant tree in the cloud forest of Santa Cruz Island but suffers from competition with the invasive blackberry Rubus niveus. At the site Los Gemelos, a S. pedunculata population was monitored from 2014 to 2021 following mechanical and chemical removal of R. niveus from 17 plots and compared with 17 additional plots where R. niveus remained. The aim of this study was to evaluate the impacts of the R. niveus invasion on S. pedunculata by characterizing the effects of R. niveus removal. Parameters measured in S. pedunculata were diameter at breast height (DBH, from which annual growth rates were determined), total height, survival of individual plants, and recruitment. In the presence of R. niveus, S. pedunculata trees had smaller DBH stems and shorter asymptotic maximum heights, growth rates declined for thin trees, the mortality of larger trees was elevated, and S. pedunculata recruitment was absent. R. niveus removal resulted in DBH-ratios of S. pedunculata more frequently meeting our threshold for fast growth (1.2), trees growing significantly thicker and taller, annual mortality being lower (12.5% vs. 16.2% per year), and recruitment being successful. In the presence of R. niveus, lower survival, growth, and absent recruitment suggested that S. pedunculata could reach quasi-extinction in ~20 years. Swift and decisive management action is needed to prevent the Scalesia forest on Santa Cruz Island from disappearing in less than two decades.

Developing alternatives to adaptive silviculture: Thinning and tree growth resistance to drought in a Pinus species on an elevated gradient in Southern Spain

Forest plantations are more vulnerable to the stress induced by biotic and abiotic factors than are naturally regenerated forests. These effects can be aggravated by a lack of management in large reforestation areas, and thinning could, therefore, help trees to reduce dieback and tree mortality related to drought. We address this question using a dendrochronology and modelling approach to improve the understanding of the growth response of high-density planted pine forests to thinning in drought-prone areas of Southern Spain. An experimental trial was, therefore, carried out with three species (Pinus halepensis, P. nigra, and P. sylvestris) and three thinning treatments (unthinned, moderate, and heavy thinning), after which growth-climate relationships and drought vulnerability indices were assessed. Three separate generalized linear mixed-effects models (GLMM), one for each species and location, were fitted using BAI as the response variable, and post-thinning growth trajectories and drought vulnerability indices were also simulated. Ten-year basal area showed strong growth responses following the thinning treatment (BAI10, 72% for P. halepensis and 50% for P. sylvestris as regards heavy thinning and 51% for P. nigra as regards moderate thinning), with different responses to precipitation and temperature according to species and thinning intensity. The significant effects of thinning on drought vulnerability indices indicated that the thinning treatments had a positive effect, irrespective of the pine species, although this was more evident in the case of P. sylvestris (recovery F = 28.10, p < 0.001, and resilience F = 35.21, p < 0.001 respectively) and P. halepensis (recovery F = 10.97, p < 0.001 and resilience F = 16.91, p < 0.001). The models also showed that climatic effect was greater for P. nigra than for P. sylvestris. The simulation also provides information on the long-term effectiveness of thinning; in P. sylvestris the effect of thinning tended to be attenuated after 20 years, but this was not the case of P. nigra and P. halepensis. High values of modelled resilience were found after thinning, with a time to recovery of between two and four years after drought depending on thinning intensity. Our findings showed the advantages of thinning for growth under different climatic constraints, particularly drought. This work is a new contribution that demonstrates the urgent need for forest managers to take steps in order to help drought-vulnerable Mediterranean pine plantations to adapt to the risks posed by climate change.

Oak savanna vegetation response to layered restoration approaches: Thinning, burning, and grazing

Temperate savannas are unique, biodiverse ecosystems that have undergone extensive habitat conversion globally. In the midwestern United States, 99% of historic oak savanna area has been lost. Most remaining patches of savanna are degraded due to woody encroachment following the removal of both fire and large herbivore disturbances from the landscape. Restoring degraded savanna remnants is challenging because we lack an understanding of how to best apply contemporary restoration tools to mimic historic disturbance dynamics. To that end, we evaluated the outcomes of ongoing oak savanna restorations that have received a gradient of restoration actions: 1) no management, 2) tree thinning, 3) thinning + burning, and 4) thinning + burning + cattle grazing. We assessed several metrics of restoration success including canopy, shrub, herbaceous, and non-native cover, herbaceous diversity, and plant community composition. We found that layering restoration approaches achieved certain, but not all, structural vegetation goals. Compared to no management, thinning and fire successfully increased canopy openness, herbaceous cover, and herbaceous diversity, but had the unwanted effect of increased shrub cover. The addition of low-intensity cattle grazing did not improve structural outcomes. We also found that each restoration treatment left a unique signature on understory plant community composition. Unmanaged and thin-only treatments were characterized by tree saplings and woodland herbs, while burned and grazed treatments were defined by shrubs and savanna-associate species. We conclude that reintroducing multiple disturbances does not guarantee the successful restoration of disturbance-dependent ecosystems such as oak savannas. Restoration outcomes are not dictated by how many management approaches are applied, but rather, the nuances of how they are applied such as burn season and livestock density.

Thinning Levels of Laurel Natural Regeneration to Establish Traditional Agroforestry Systems, Ecuadorian Amazon Upper Basin

(1) Background: The Cordia alliodora (Ruiz &amp; Pav.) Oken (laurel) natural regeneration management is a widespread practice among smallholders in the Amazon upper basin for the establishment of traditional agroforestry systems. This tree management approach is opposite to the development project proposals that contemplate reforestation with nursery seedlings in the Amazon region. The present study evaluated the effects of thinning levels on the diameter and basal area increment of laurel in a traditional agroforestry system; (2) Methods: A randomized complete block design with three replications was used, and the target variables were the growth rate of diameter at breast height (DBH) and the basal area of trees. Twelve square field plots, 400 m² each, were established in a plot network covering a 1.0 km × 0.5 km area. Three thinning levels were applied: light, moderate, and intensive thinning; (3) Results: The traditional agroforestry system investigated was characterized by a marginal growth of laurel trees, with an average yield of 125.26 m3 ha−1 (±15.39) and MAI of 13.92 m3 ha−1 at 9 years of age with a tree density of 418 trees ha−1. The average value of the relation between the number of trees and the basal area removed (NG value) was 1.15, with small variation among plots, so all of them were thinned from below. The intensive thinning treatment, leaving 200 trees ha−1, caused the greatest annual increase in individual tree DBH (2.03 cm) and basal area (61.37 cm2) in both absolute and relative terms and improved tree height/diameter ratio; (4) Conclusions: Management of laurel natural regeneration for the establishment of traditional agroforestry systems could be improved by thinning at early ages, leaving 200 well-spaced laurel trees per ha.

The Impact of Plant Growth Regulators and Floral Cluster Thinning on the Fruit Quality of ‘Shine Muscat’ Grape

Plant growth regulators (PGRs) and floral cluster thinning are commonly used to improve grape yield and quality, but their effects on different fruit quality attributes in the ‘Shine Muscat’ are not well understood. In this study, we investigated the impact of PGRs and floral cluster thinning on various fruit quality parameters such as the cluster weight, berry weight, diameter, shape, sugar and acid content, firmness, and residual feel of peel. Our results indicate that the gibberellic acid 3 (GA3) 25 mg/L + thidiazuron (TDZ) 5 mg/L treatment at full bloom and GA3 25 mg/L treatment at 12 days after full bloom showed the largest cluster weight, berry weight, and diameter, while the forchlorfenuron (CPPU)-treated group, with a more balanced effect on fruit skin and flesh firmness, had the highest proportion of a positive residual feel of the peel. Floral cluster thinning by 4 cm was found to be effective for promoting fruit growth and maintaining an appropriate sugar–acid ratio, while thinning by 5 cm resulted in a higher number of berries but smaller berry size and lower sugar–acid ratio. These findings can be useful for grape growers and researchers in optimizing PGR and floral cluster thinning treatments to improve grape yield and quality.

Improving Sustainable Forest Management of Pinus halepensis Mill. Mid-Aged Stands in a Context of Rural Abandonment, Climate Change, and Wildfires

Pinus halepensis Mill. covers most lowland forests on limestone soils and semiarid to sub-humid climates in the Mediterranean basin. It is considered a key species in climate change due to its pioneer nature, versatility, and flexibility. Moreover, its industrial potential is an additional incentive to promote forest management to increase its quality and productivity while contributing to other environmental and social objectives. However, there is a considerable gap in science-based knowledge on the effects of different silvicultural treatments on Pinus halepensis stands. Thus, this research compares the impact of four different treatments (light thinnings, strong thinnings, transformation to uneven-aged, and diameter-driven uneven-aged) on even-aged mid-rotation stands of Pinus halepensis in terms of growth, vulnerability, and resilience to extreme weather events, regeneration, and shrub cover. The effects of four treatments are evaluated in 12 research plots of 0.49 ha each (three per treatment) and contrasted with the other three non-managed control plots. Light and strong thinning treatments show better growth—at least in the short term—and stock results than those reported in the reference yield tables. Transformation to uneven-aged treatment shows advantages in maintaining periodic growth, regeneration, and stability. In addition, it offers an alternative for steep slope stands, smallholders, and extended narrow-aged estates to speed up the desirable balanced age class distribution. Diameter-driven uneven-aged treatment implies greater vulnerability to extreme weather events during the first years and considerable stock reduction while offering faster and taller tree regeneration. A dual regeneration pattern of Ulex parviflorus Pourr is observed in addition to post-fire regeneration in the case of sudden and well-distributed tree cover reduction around 40% of the canopy due to the transformation into the uneven-aged stand. An observation period longer than a decade of the research plots will confirm these first conclusions.

Wood Physical and Mechanical Properties of Clonal Teak (Tectona grandis) Stands Under Different Thinning and Pruning Intensity Levels Planted in Java, Indonesia

The objective of this study was to reveal the impact of thinning and pruning regimes on the physical and mechanical properties of clonal teak wood planted in Java. In this study, a 15-year-old clonal teak plantation was carried out and the obtained data were evaluated with analysis of variance (ANOVA). The results showed that different thinning intensities had a significant impact on the alteration of heartwood volume development (F = 25.63; p &lt; 0.0001). Meanwhile, the impact of different thinning treatments in several physical properties depends on the pruning treatment levels [moisture content (F = 12.18, p &lt; 0.0001); tangential shrinkage (F = 15.60, p &lt; 0.0001); T/R ratio (F = 7.17, p &lt; 0.0001); and volumetric shrinkage (F = 10.81, p &lt; 0.0001)]. However, different thinning intensities had no significant impact on wood basic density alteration (F = 0.72, p = 0.486), while pruning intensities affect the differences between radial (F = 3.52, p = 0.030) and volumetric shrinkage (F = 3.13, p = 0.044). In mechanical properties, thinning intensity levels did not promote any significant differences [modulus of elasticity (F = 1.41, p = 0.248); modulus of rupture (F = 0.94, p = 0.392); compressive strength parallel to grain (F = 0.21, p = 0.813); and compressive strength perpendicular to the grain (F = 0.41, p = 0.669)]. Meanwhile, different pruning treatments and combination treatments were not significantly altered all mechanical properties. These results indicated that the thinning and pruning regimes can enhance the mechanical properties without having a serious alteration in the physical properties of clonal teak wood.

Wreathed in Worry, Pining for Protection: Latino Forestry Workers and Historical Traumas in Maine

Most of the workers in the van were sleeping because of the early morning hour, but Edilberto Morales-Luis was feeling nervous. Their driver—who was trying to cover the three-hour commute to the forest quickly to compensate for lost time due to rain—was barreling down a dirt road amid gusty winds. “Why don't you drive a little bit slower?” Morales-Luis called out, only to have a co-worker tease him for being afraid. It was September 12, 2002, and the crew of fourteen Guatemalan and Honduran H-2 visa guest workers had been hired to thin trees and clear brush for six months in Aroostook County, a remote part of northern Maine bordering Canada. They were working for Evergreen Forestry Services, an Idaho-based reforestation company subcontracting for the Maine-based Seven Islands Land Company.1 As the driver, Juan Turcios-Matamoros, transferred from the dirt road onto Johns Bridge, a narrow 260-foot wooden bridge with no guardrail perched over the Allagash Wilderness Waterway, the right side of the van missed the bridge planks and caught on an outer row of steel bolts. The tires started shredding. Startled, several passengers implored him to slow down; they were less than five miles from their destination. Instead of braking, Turcios-Matamoros maintained his speed and tried to steer the right wheels back onto the planks but overcorrected. The van took a sickening skid before flipping over and plunging off the bridge into the whirling water beneath. Shocked but aware he needed to act quickly, Morales-Luis swam to the back of the van, kicked out the rear window, and pushed his way out. “I fought to get [the rest of] them out of there. But I couldn't,” he later said. The van filled rapidly with water, and the fourteen other men—who included his own uncle—sank to the river bottom. Edilberto swam to shore to get help, but the accident had happened so far from any trafficked roadway that he had to wait half an hour to flag down a passing vehicle. It then took almost four hours for rescue crews to arrive. The state police and national guard deployed helicopters and floatplanes, and rescuers were able to eventually heave the van—which still held the bodies—out of the water and onto a large flatbed truck. Juan Perez-Febles, an employee of the Maine Department of Labor's Migrant and Immigrant Services Division, joined a caravan of vehicles that escorted the truck to the Maine Medical Examiner's Office. There, he saw the victims' bodies jumbled together with saws, blades, gasoline cans, and lunch pails. “The tangled mess of flesh, vomit coming out of their mouths…. You could see the panic in their faces,” he said. Perez-Febles stayed at the office to interpret for the lone and stressed survivor, Morales-Luis, who identified his co-workers and reconstructed the accident for officials and the media.2

Temporary thinning shock in previously shaded red spruce

Silvicultural thinning can lead to rapid microclimatic changes for residual trees. Despite the benefits of decreased competition, thinning may induce “thinning shock”—temporary negative physiological responses as trees acclimate to new conditions. We examined the impact of thinning on the microclimate and physiology of residual, previously shaded red spruce ( Picea rubens Sarg.) trees relative to non-thinned controls. Both daily maximum temperature and vapor pressure deficit increased post thinning, with larger increases observed on hotter and drier days. In response to these environmental changes, we found clear evidence of physiological declines. At 1.7 weeks post thinning, we found a 0.59 MPa reduction in average midday water potential relative to control trees, which lasted for an additional 1.4 weeks. Thus, the trees in the thinning treatment were at or beyond published estimates of needle turgor loss. Thinning decreased the photosynthetic efficiency of current-year needles by 3.8% after 2 weeks, and it declined by 1.3% per week for the remainder of the growing season. These results suggest that thinning shock occurs in red spruce, a shade-adapted, climate-sensitive species. Thinning shock may contribute to the lagged growth responses commonly observed post thinning, and these effects may be more extreme in novel future climates.

Comparing the influence of thinning treatments with low to high residual basal area on red maple transpiration in a temperate mixed forest

Under climate change, forests are expected to experience drier conditions that may increase tree mortality. Silvicultural treatments, such as thinning, have been proposed to reduce moisture competition and to improve forest resistance to drought events. Most studies have investigated the effectiveness of thinning under semi-arid conditions, while little information is available regarding temperate forest responses, together with the residual basal area (BA) that is required to reap the benefits of these treatments. This research aims to understand how the residual BA influences transpiration in mixed temperate forest stands that are dominated by red maple (Acer rubrum) in southeastern Canada. We monitored the sap flux density (Fd) with thermal dissipation-type sensors for 18 red maples spread across three sites that were each thinned to obtain a gradient of residual BA (20, 12.5, 6 m2/ha). The study was conducted during the first growing season following treatment. Low residual BA plots (6 m2/ha) incurred drier atmospheric conditions as shown by a greater vapor pressure deficit (VPD) compared to high residual BA plots (20 m2/ha), although we observed considerable variability between sites. At the tree scale, Fd increased with residual BA, with the most pronounced differences under dry atmospheric conditions: when daily VPD exceeded 1.1 kPa, mean Fd in high residual BA plots was respectively 20 % and 75 % greater than in medium (12.5 m2/ha) and low residual BA plots. At the stand level, we simulated total transpiration considering the stand as only made of red maples. The transpiration in medium and low residual BA plots amounted to 41 % and 79 % of transpiration simulated in the high residual BA plot. Overall, this work highlighted broad variation in response to residual BA treatments, emphasizing the need to better model forest water budgets, and partitioning overstory and understory evapotranspiration to make more adequate residual BA prescriptions in temperate forests.

Changes of Rainfall Partitioning and Canopy Interception Modeling after Progressive Thinning in Two Shrub Plantations on the Chinese Loess Plateau

Understanding the interaction between the hydrological cycle and vegetation management strategies, such as thinning, is essential to improve watershed management and support ecological services. However, it remains unclear how thinning affects the key components of hydrological cycle of dense shrublands in the semiarid regions. Thus, the purpose of this study was to analyze and evaluate the effect of thinning on rainfall partitioning and interception simulations in dense shrublands. In a 5-year field experiment, we compared rainfall partitioning in two re-vegetated shrublands (Caragana korshinskii and Salix psammophila) in the Chinese Loess Plateau under two thinning intensities (moderate thinning [MT] and heavy thinning [HT] refer to the removal of 25% and 50% of the branches, respectively) or no thinning (NT) (control). We modeled canopy interception losses (I) in the two thinning treatments and control treatment using the revised Gash model. The results showed that under MT and HT, the throughfall (TF) rate increased by about 12% and 20%, respectively, compared to NT. The stemflow (SF) and observed I rates decreased by about 26% and 33%, respectively, under MT, and the corresponding values for HT were about 50% and 52%, respectively. The observed I rate decreased proportional to the percentage of biomass removed from the C. korshinskii and S. psammophila plots. The results also revealed a significant linear correlation between the plant area index (PAI) value and the canopy water balance of the two shrub plantations (R2 > 0.83, P < 0.05). The performance of the revised Gash model (i.e., relative error [RE] < 20%) was satisfactory according to the Nash − Sutcliffe model efficiency (NSE) coefficient (0.34–0.71). Based on the RE values, the performance of the revised Gash model was better when applied to the plots subjected to MT and HT (RE ≤ 3%) than NT (RE = 9.3%) for S. psammophila. Changes in the canopy storage capacity and canopy evaporation rate strongly affected changes in simulated interception loss. The model can facilitate water management in semiarid shrub plantations by accurately simulating the effect of thinning on interception loss.

Sub-resolution contrast in neutral helium microscopy through facet scattering for quantitative imaging of nanoscale topographies on macroscopic surfaces

Nanoscale thin film coatings and surface treatments are ubiquitous across industry, science, and engineering; imbuing specific functional or mechanical properties (such as corrosion resistance, lubricity, catalytic activity and electronic behaviour). Non-destructive nanoscale imaging of thin film coatings across large (ca. centimetre) lateral length scales, crucial to a wide range of modern industry, remains a significant technical challenge. By harnessing the unique nature of the helium atom–surface interaction, neutral helium microscopy images these surfaces without altering the sample under investigation. Since the helium atom scatters exclusively from the outermost electronic corrugation of the sample, the technique is completely surface sensitive. Furthermore, with a cross-section that is orders of magnitude larger than that of electrons, neutrons and photons, the probe particle routinely interacts with features down to the scale of surface defects and small adsorbates (including hydrogen). Here, we highlight the capacity of neutral helium microscopy for sub-resolution contrast using an advanced facet scattering model based on nanoscale features. By replicating the observed scattered helium intensities, we demonstrate that sub-resolution contrast arises from the unique surface scattering of the incident probe. Consequently, it is now possible to extract quantitative information from the helium atom image, including localised ångström-scale variations in topography.

Effects of thinning on soil nutrient availability and fungal community composition in a plantation medium-aged pure forest of Picea koraiensis

Thinning is an important silvicultural practice for improving the productivity and wood production in plantation forest. Different intensities of thinning management can affect tree growth and alter soil nutrient effectiveness, thus affecting soil fungal community structure and diversity. Our objective is to determine the soil factors and their regulatory mechanisms that influence stand growth by thinning, and to provide data to support the establishment of large diameter timber cultivation technology for Picea koraiensis. In this study, we conducted medium- and high-intensity thinning in 43a P. koraiensis plantation middle-aged forests and investigated the growth indexes, soil physicochemical properties, and fungal community diversity in rhizosphere and non-rhizosphere soils of the stands after thinning at different densities (904 plants/ha for control, 644 plants/ha for 30% thinning intensity, and 477 plants/ha for 50% thinning intensity). The results showed that all growth indicators (annual growth of tree height, diameter at breast height, height under live branches and crown width) of the plantation after high-intensity thinning (477 plants/ha) were higher than those of the control (no thinning, significant) and medium-intensity thinning (644 plants/ha). Mycorrhizal infection rate was higher at the beginning of the growing season than at the end of the growing season, and increased slightly with decreasing stand density. Compared to the control, all medium- and high-intensity thinning treatments significantly improved soil nutrient content (P < 0.05), including total carbon, total nitrogen, total phosphorus, total potassium, Available phosphorus and Available potassium. Fungal diversity was higher but lower in abundance than the control in both rhizosphere and non-rhizosphere soils after thinning. The number of OTUs and fungal richness and diversity indices of non-rhizosphere soil fungi were higher than those of rhizosphere soil fungi. In conclusion, this study provides new evidence that reasonable intercalation can increase the radial and vertical growth of P. koraiensis plantation forests and promote the diversity of subsurface soil fungal communities. It is shown that thinning intensity regulates biogeochemical cycles in P. koraiensis plantation ecosystems by affecting soil nutrients and fungal community structure. Therefore, 50% thinning intensity can be used to increase timber production in plantation forests during large diameter timber cultivation of P. koraiensis and improve predictions associated with achieving long-term forest management strategies.

PENGARUH JENIS PUPUK ORGANIK DAN PENJARANGAN BAKAL BUAH TERHADAP PERTUMBUHAN DAN HASIL MELON

Utilization of organic matter as a plant nutrition can be used to increase the growth and yield of melon cultivation. Fruit thinning treatment can be used to improving fruit quality. This study aims to examine the effect of various organic fertilizers and fruit thinning on the growth and yield of melons. The study was conducted in Screen house Universitas Perjuangan Tasikmalaya from March to June 2021. The study used a factorial completely randomized design. First factor is type organic fertilizer consist of solid chicken manure, vegetable waste liquid fertilizer, and cow urine. Second factor is fruit thinning consist of 1 and 2 remaining ovules. Based on the research results, the interaction of vegetable waste with the remaining 1 ovule resulted in the highest number of leaves compared to other interactions. Chicken manure and vegetable waste with 1 and vegetable waste with 2 ovules produced the greenest leaves compared to other interactions. The application of organic fertilizer had no significant effect on plant biomass, root length, fruit diameter, fruit thickness, total dissolved solids, and productivity. Fruit thinning significantly affected to plant biomass, root length, fruit diameter, fruit thickness, fruit weight per plant, and productivity. 1 ovule was the best treatment compared to 2 ovules. Provision of vegetable waste with 1 and 2 ovules affects the growth and yield of melon plants. Fruit thinning by leaving 1 ovule effectively to growth and yield of melons.