Strip Cut Research Articles

Forest stand dynamics of a short‐stature tree species: Ecological knowledge for sustainable forest management

Abstract Worldwide, the implementation of forest management guidelines has tried to mimic natural forest dynamics. The Oliver forest stand dynamics model has been successful in bridging natural forest dynamics associated with the disturbances of various spatial scales and silviculture also related to various spatial scales of management. However, the application of this model (and others) is restricted to tall forests. We claim here that the general research and commercial interest bias towards tall tree species has permeated silviculture and forest management, and that both the stand dynamics of short‐stature tree species and their treatment have remained largely unexplored and unknown. Using one short‐stature tree species, Nothofagus antarctica, as a model system, we show that this species indeed follows a stand dynamic different from other tall Nothofagus‐dominated forests in southern South America. This species forms short, mature, even‐aged stands without large canopy gaps that promote tree regeneration. With this in mind, we propose a conceptual ecology‐based silvicultural guideline focusing on the creation of strip cuts or gaps along with topsoil scarification to ensure regeneration and forest reorganization after disturbances. Policy implications. The acknowledgement that short‐stature tree species follow a stand dynamic different from tall tree species necessarily implies that they must be managed differently. This recognition, along with the implementation of ecology‐based silvicultural recommendations, represents strong arguments to make modifications to forest legislation that, together, must be aimed at conservation and sustainable forest management.

Effect of Fertilization on Soil Fertility and Individual Stand Biomass in Strip Cut Moso Bamboo (Phyllostachys edulis) Forests

Strip cutting has emerged as a new, efficient, and mechanized bamboo forest management model. To shorten the recovery period in strip cutting management, improve bamboo resource quality, prevent soil degradation, and achieve sustainable management, we selected on-year pure Moso bamboo (Phyllostachys edulis) forests for an 8-meter-wide strip cut. Three fertilization methods were applied in a complete two-factor experiment, including spreading, cave, and bamboo stump fertilization, at three fertilization dosages of 600, 900, and 1200 kg/ha (N:P:K = 3.5:1:2). We investigated the effects of different fertilization treatments on the biomass of new bamboo shoots and soil fertility to provide a reference for identifying the optimal fertilization scheme. The results showed that fertilization treatment increased the individual stand biomass of new Moso bamboo shoots, with a decreasing trend in the proportion of branches and leaves and an increasing proportion of culms in biomass allocation. Fertilization treatment significantly increased the total nitrogen, phosphorus, and potassium and available phosphorus contents in the soil. Overall, fertilization at 900 kg/ha using the spreading method showed the best results in promoting individual plant biomass recovery (5% increase in culm proportion and 4.12 kg increase in biomass per plant) and restoring soil fertility (increase the contents of TN, TP, TK, and AP in the entire soil layer) after strip cutting Moso bamboo forests, which addresses these pertinent issues in the strip cut management model.

Wideband Multifunctional Polarization Converter: Application to Low Radar Cross-Section Radiating System

In this article, a wideband linear-to-linear and linear-to-circular reflective polarization converter is discussed. The proposed polarization converter can efficiently convert an incoming wave with a linear polarization into a reflected wave with orthogonal polarization in the frequency ranges: 7.63–12.21 GHz and 19.34–21.2 GHz. Moreover, a circularly polarized reflected wave in the frequency band of 13.85–18.50 GHz is also obtained. The proposed polarization converter constitutes a split-ring and a metallic strip cut in the middle designed on an ultrathin single substrate layer (thickness of 0.079λ o, where λ o corresponds to wavelength at center frequency of lowest operational bandwidth). The study related to angular dependence of the proposed polarization converter is also carried out and a stability upto 15° is achieved at the lower and upper-frequency bands of operation, respectively. A prototype of the proposed polarization with 25 × 25 cells of the converter is fabricated and measured. Measurement results are in consensus with their simulated counterparts. Furthermore, a 12 × 12 array of the proposed polarization converter is used to study the radar cross-section (RCS) reduction ability of a microstrip patch antenna operating in X-band. The average RCS reduction of about 11 dBsm is obtained at normal incidence. The proposed polarization converter can be utilized in X/Ku/K frequency band applications.

Optimizing the slicing pattern of stress-relief crystal analyzers for X-ray Raman scattering

X-ray Raman scattering (XRS) spectroscopy is an emerging inelastic scattering technique used to measure local electronic structure and chemical bonding around low-Z atoms with hard X-rays. This technique is useful in environments where traditional soft X-ray techniques are not applicable. However, the small cross section of XRS requires that the spectrometer must simultaneously achieve large solid angles and good energy resolution. A large XRS spectrometer named `Qian Kun' is currently under construction at the High Energy Photon Source (HEPS) in China, which can hold up to 100 analyzers with an energy resolution in the range 0.4–1.0 eV. Here, the batch production and performance evaluation of the spherically bent crystal analyzers fabricated for this spectrometer are reported. The stress-relief effect of various dicing patterns and their impact on the reflectivity properties of crystal analyzers to achieve good energy resolution when studying the near-edge features of carbon and oxygen K edges were investigated. It was discovered that radially dicing the thin silicon wafers is more effective in relieving stress than conventional strip cuts in the case that the total number of divided blocks is roughly the same.

Effects of Different Harvesting Methods on Aboveground Nutrient Pools of Moso Bamboo (Phyllostachys edulis) Forest in China

Improved knowledge of nutrient removals from harvesting is essential for the sustainable management of Moso bamboo forests. In particular, the growth and development of bamboo forests are considered to meet the increasing demand for biomass energy. In this study, plots with an 8 m width strip cut (SC) after five years of restoration were selected as the research object and the traditional management forest (CK) as the control. The nutrient content and biomass of Moso bamboo at different ages were studied and the nutrient storage was calculated. The results showed that five years after cutting, the soil nutrient content in different soil layers and the aboveground nutrient storage reached the same level as the CK. The nutrient ranking of each organ of Moso bamboo was nitrogen > potassium > phosphorus. The phosphorus content of bamboo culm in CK was significantly higher than that in SC at different ages (p < 0.05). The biomass accumulation of each organ of Moso bamboo was culm > branch > leaf. In addition, the relationship between nutrient storage and DBH and density in SC is a simple power form, and the coefficient of determination of most computational models is above 0.9. Our results demonstrated that strip cutting is more economical than traditional management, but nutrient addition is needed to improve the quality of new bamboo trees at the initial stage of recovery in consideration of long-term productivity maintenance.

Dynamics of stand productivity in Moso bamboo forest after strip cutting.

Strip cutting can effectively reduce the cutting cost of bamboo forests and promote the transformation and upgradation of bamboo forests through mechanization and modernization. Despite the rapid accumulation of Moso bamboo biomass, the dynamics of five years changes in stand characteristics and productivity after cutting remain unclear. This is critical for formulating efficient bamboo forest management measures. In this paper, plots with an 8m width strip cut (SC) and respective reserved belts (RB) were selected as the research object, and the traditional management forest (CK) as control. The dynamic characteristics of stand, biomass distribution pattern, and productivity change in the different treatment plots were studied for 5 years after cutting. The results showed that cutting increased the number of shoots and new bamboo, and decreased the diameter at breast height, height to crown base, and height of new bamboo (p<0.05). Cutting reduces the productivity of both SC and RB, and allocates more biomass to the bamboo leaves to capture light in SC (p<0.05). Over time, the characteristics of new bamboo in SC reached the level of CK, and the density of standing bamboo, and productivity, were higher than those in CK. However, the number and productivity of new bamboo decreased significantly in the RB (p<0.05), which reflected the density restriction effect of bamboo forest. Further analysis showed that the increase in productivity in SC and CK was mainly from Moso bamboo at II and III "du", which positively correlated with the soil contents of total nitrogen, total phosphorus, and available phosphorus. It was suggested that after three On-year restorations, the SC could reach the level of CK, however it is necessary to density manage RB from the second On-year after cutting.

Measuring and Modeling the Effect of Strip Cutting on the Water Table in Boreal Drained Peatland Pine Forests

Strip-cutting management has been proposed as an alternative to clear-cuts in drained boreal peatland pine (Pinus sylvestris L.) forests. We explored the hydrological feasibility of strip cutting, that is, under which conditions the post-harvest water table (WT) in peat remains sufficiently deep (here, a WT of −0.35 m during the late growing season) to enable undisturbed tree growth. We approached the question by (1) measuring the WTs in a harvested strip and an adjacent unharvested stand in peatland forests in southern Finland and (2) by simulating the WTs in different strip cut layouts, unharvested peatland, and clear-cut cases using a process-based hydrological model. The measured WTs were, on average, 0.06–0.12 m closer to the peat surface in the harvested strips than in the unharvested stands. The hydrological feasibility of strip cutting increased along with increasing site productivity and improving climate conditions. Strip cutting resulted in the rise in the WTs of adjacent unharvested stands, which can have undesired consequences. Depending on the stand density and strip cut layout, the share of the well-drained area in the harvested strips was slightly larger or even two times larger compared to a complete clear-cut of the forest. Narrow strips (here, 13 m in width) indicated better drainage in the harvested area than wider (20–30 m in width) strips. Even though strip cutting has limited capacity to maintain efficient drainage in the harvested strip on low hydraulic conductivity peat, the increase in the WT was smaller than after clear-cut.

Reconstructing Soil Recovery from Acid Rain in Beech (Fagus sylvatica) Stands of the Vienna Woods as Indicated by Removal of Stemflow and Dendrochemistry

Our goal was to reconstruct soil recovery from Acid Rain based upon removal of stemflow at beech (Fagus sylvatica) stands of known historic and recent soil status. Fourteen beech stands in the Vienna Woods were selected in 1984 and again in 2012 to study changes in soil and foliar chemistry over time. A part of those stands had been strip cut, and to assess reversibility of soil acidification, we analyzed soils around beech stumps from different years of felling, representing the years when acidic stemflow ceased to affect the soil. Furthermore, it was hypothesized that changes of soil chemistry are reflected in the stemwood of beech. Half-decadal samples of tree cores were analyzed for Ca, Mg, K, Mn, Fe, and Al. Soil analyses indicated recovery in the top soil of the stemflow area but recovery was delayed in the between trees areas and deeper soil horizons. Differences in soil pH between proximal and distal area from beech stumps were still detectable after 30 years indicating that soils may not recover fully from acidification or do so at a rather slow rate. Stemwood contents indicated mobilization of base cations during the early 80s followed by a steady decrease thereafter. Backward reconstructions of soil pH and soil nutrients, building on regressions between recent stemwood and soil chemistry, could not be verified by measured soil data in 1984, but matched with declining cation foliar contents from 1984 to 2012. Dendrochemical reconstructions showed highest values in the 1980s, but measured soil exchangeable cation contents were clearly lower in 1984. Hence, we conclude that our reconstructions mimicked soil solution rather than soil exchanger chemistry.

Study on specimens shapes for tensile test of Malaysia bamboo

In Malaysia, the bamboo is rarely used in structural elements due to the lacks of understanding on the feasibility and potential of bamboo and its behavior when subject to load. The strength should be fully understood as the structure is intended to take higher loads. Till now, the strength data for Malaysia bamboo is unavailable. Thus, testing on bamboo should be done to get the correct data. However, the tensile procedure on specimen preparation suggested by many codes lead to incorrect failure modes where most of the tensile test end-up with failure at the grip rather than at the gauge length or between the grips. Therefore, thorough investigation on the specimen shape is needed to ensure that the correct failure modes is obtained. Bambusa Vittata was prepared and cut into strips with average size of 200 mm long, 15 mm wide and 9 mm thick. The specimens were then trimmed to the required shape. A total of 20 specimens were divided into four groups with different shapes, namely S (strip cut), SS (strip cut-side curve), DC (double curve) and SC (single curve). Tensile strength tests were carried out on these four groups with average dry moisture content between 9 % -16 % after air-dried. Based on the testing, the results show that the appropriate cutting pattern for tensile test was SS, followed by DC, S and SC. The failure pattern of bamboo occurred for SS was exactly at the gauge length area as compared to the other specimens with maximum average stress and strain of 201.9 kN/mm2 and 1.227 % respectively.

Influence of gap position and competition control on the leaf physiology of planted Picea glauca and natural regeneration of Populus tremuloides

Maintaining white spruce (Picea glauca (Moench) Voss) in mixture with trembling aspen (Populus tremuloides Michx.) and other broadleaf competitors following timber harvest in boreal and sub-boreal mixed-wood stands is challenging. Under-planting spruce within harvest gaps is one potential strategy, but it’s unclear which gap environments favor spruce in relation to aspen. Here we test the effect of gap position and woody release treatment on leaf area development and growth physiology of spruce and aspen. Five positions were measured from the southern understory through the gap center to the northern understory in replicated strip cuts. The woody release treatment cut all stems around spruce including aspen in subplots within each experimental gap; other subplots were left un-cut for comparison. We measured leaf area per wet weight, leaf photosynthesis, stomatal conductance, and transpiration in low- and full-light conditions. We also assessed photosynthetic plasticity in relation to light. Overall, aspen maintained higher leaf area per unit wet weight than spruce, but spruce leaf area was more sensitive to changes in gap position. Aspen also maintained higher photosynthesis and transpiration rates than spruce under both light conditions, and woody release treatment. The magnitude of difference in gas exchange rates between the two species, however, depended significantly on woody release treatment and gap position for photosynthesis, and on gap position for transpiration. Photosynthetic plasticity was not significantly different across species, gap position, or woody release treatment. Our results indicate that in order to ensure the competitive advantage of spruce in mixed-wood boreal stands, forest managers should concentrate spruce planting and competition control efforts in the centers of canopy openings.

Assessment of the impact of forest harvesting operations on the physical parameters and microbiological components on a Mediterranean sandy soil in an Italian stone pine stand

Forest harvesting operations may have a significant impact on soil physical properties by reducing its porosity and organic functions. Soil variations, in particular bulk density and total porosity, caused by external perturbations as soil becomes compacted due to machinery passes, can lead to changes in biogeochemical cycles that have consequences on soil ecosystems. This study investigated how the impact of forest operations and the elapsed time from harvest can influence: (1) the physical–chemical characteristics of soil and (2) the nitrogen-fixing and nitrifying microbial communities. The study area is located inside the Regional Park of Migliarino, San Rossore, Massaciuccoli (Pisa, Italy). In the study area, the soil has been classified as recent sands with sandy loam texture and slightly calcareous (USDA Soil Taxonomy classification). Soil samples were collected in patchy cut areas (strip cut) of Pinus pinea stand that was harvested in two steps: half area in 2006 and the rest in 2011. Soil samples were collected also in a control area (not harvested) with similar stand and soil characteristics. Statistical analysis was preceded by a test of normality (Kolmogorov–Smirnov test) and a variance homogeneity test (Levene’s test). Considering the dependence of the variables studied (physical and chemical soil characteristics), a MANOVA test and a post hoc Tukey HSD test were applied to determine statistical difference among the three treatments: harvested 2006, harvested 2011 and not harvested. The results did not indicate significant variations to the parameters of shear and penetration resistance, though soil bulk density and total porosity were significantly altered in the short period since forestry operations occurred. These physical changes induced qualitative (presence/absence and number of species) and quantitative (abundance and spatial evenness of the species) variations in the nitrogen-fixing and nitrifying microbial communities.

Can native plant species be preserved in an anthropogenic forest landscape dominated by aliens? A case study from Mediterranean Chile

Plantations with fast growing exotic tree species can negatively affect native plant species diversity and promote the spread of alien species. Mediterranean Chile experienced major landscape changes with a vast expansion of industrial plantations of Pinus radiata in the past. However, with increasing knowledge of biodiversity effects on ecosystem services Chilean forest owners now aim to integrate the conservation of native biodiversity into forest management, but data on native species diversity and establishment within a plantation landscape is scarce. Here we investigated plant species diversity and composition in four forest management options applied within a landscape dominated by P. radiata plantations in comparison to an unmanaged reference: (i) a clear cut, (ii) a strip cut, (iii) a native canopy of Nothofagus glauca and (iv) a young P. radiata plantation. We wanted to assess if native plant species can be maintained either by natural regeneration or by planting of native tree species (Nothofagus glauca, N. obliqua, Quillaja saponaria) within this landscape. Results show a high diversity of native and forest plant species within the different management options indicating a high potential for native biodiversity restoration within an anthropogenic landscape. In particular, herbaceous species can benefit from management. They are rare in unmanaged natural forests that are characterized by low light conditions and a thick litter layer. Management, however, also promoted a diversity of alien species. The rapid spread of alien grass species after management can deter an initial establishment of native tree species or the survival and growth after planting mainly under dry but less under sufficient moisture conditions. The most unsuccessful option for promoting native plant species was clear cutting in a dry area where alien grasses were abundant. For drought-tolerant tree species such as Quillaja saponaria, though, even a joint establishment with Pinus radiata seems possible.

A strip cut in a composite elastic wedge

Integral equations of new three-dimensional problems concerning a cut in the plane of symmetry of a composite elastic wedge are obtained. The wedge consists of three wedge-shaped layers with a common apex, connected by a sliding clamp: in the middle there is a compressible layer with a cut, to the sides of which two identical incompressible layers are pressed. For the case of a strip cut emerging on the edge of the composite wedge, using the method of paired integral equations, the problem is reduced to Fredholm integral equations of the second kind. An expression is obtained for the stress intensity factor.

Полосовые разрезы в транстропном упругом теле

Полосовые разрезы в транстропном упругом теле

Improvised double-embedding technique of minute biopsies: A mega boon to histopathology laboratory

Optimal orientation of minute mucosal biopsies is essential for a definite diagnosis in gastrointestinal pathology or to visualize neural plexuses in Hirschsprung disease. The problem of minute size of the biopsy and its orientation gets compounded when they are from neonates and mandates exhaustive strip cuts, thus delaying reporting. A modified agar-paraffin technique is aimed to make tissue embedding efficient and user-friendly by inking mapping biopsies (one or more) either fresh or fixed with surgical coloring inks followed by embedding first in agar after orientation and followed thereafter by processing, re-embedding in paraffin wax, sectioning and staining. The tissues in agar paraffin block were found to be well processed, firm, held secure and well preserved. The blocks were easy to cut, with serial sections of thickness 2-3 μ and easy to spread. The colored inks remained permanently on the tissues both in the block as well as on the sections which helped in easy identification of tissues. Agar did not interfere with any stain such as Hematoxylin and Eosin or with histochemical stains, enzyme histochemistry or immunohistochemistry. Inking biopsies and pooling them in a block when obtained from the same patient reduced the number of tissue blocks. The modified agar-paraffin embedding technique is a simple reliable user friendly method that can greatly improve the quality of diagnostic information from minute biopsies by optimal orientation, better quality of sections, faster turnaround time and cost-effectiveness by economizing on the number of paraffin blocks, manpower, chemical reagents and laboratory infrastructure.

A strip cut in a transversely isotropic elastic solid

The three-dimensional problems of a strip cut in a transversely isotropic elastic space, when the isotropy planes are perpendicular to the plane of the cut, are investigated using the asymptotic methods developed by Aleksandrov and his coauthors. Two cases of the location of the strip cut are considered: along the first axis of a Cartesian system of coordinates (Problem A) or along the second axis (Problem B). Assuming that the normal load, applied to the sides of the cut (normal separation friction) can be represented by a Fourier series, one-dimensional integral equations of problems A and B are obtained, the symbols of the kernels of which are independent of the number of the term of the Fourier series. A closed solution of the problem is derived for a special approximation of the kernel symbol. Regular and singular asymptotic methods are also used to solve the integral equations by introducing a dimensionless geometrical parameter, representing the ratio of the period of the applied wavy normal load to the thickness of the cut strip. The normal stress intensity factor on the strip boundary is calculated using the three methods of solving the integral equations indicated.

Strip twisted electrospun nanofiber yarns: Structural effects on tensile properties

Abstract

Problems of cuts in a composite elastic wedge

Problems of strip and elliptical cuts (tensile cracks) in the middle of a three-layer elastic wedge are investigated in a three-dimensional formulation. Free or rigid clamping conditions or the stress-free condition are stipulated on the outer surfaces of the composite wedge. The problems are assumed to be symmetrical about the plane of the cut. The wedge-shaped layer containing the cut is incompressible and hinged along both faces with two other layers. The integral equations of the problems with respect to the opening of the cut are derived. Inverse operators are obtained for the operators occurring in the kernels of these equations. The relation between problems on cuts and the corresponding contact problems for a composite wedge of half the aperture angle is used. The method of paired integral equations is used for the case of a strip cut emerging from the edge of the wedge. The problems are reduced to Fredholm integral equations of the second kind in certain auxiliary functions, in terms of the values of which the normal stress intensity factors are expressed. A regular asymptotic solution is constructed for the case of an elliptic cut.

The effect of final cuts on the density, growth and health condition of pine natural regeneration in the territory of the Tuszyma Forest District

Wpływ cięć rębnych na zagęszczenie, wzrost i stan zdrowotny odnowień naturalnych sosny w warunkach Nadleśnictwa Tuszyma

Structural diversification in artificial forest stands. Results of experiment plots in eastern Andalusia

Results of experiments of diversification of stands of Pinus halepensis Mill. are presented, sixteen years after the plots installation. In the plots strip cuts of differents widths were made in order to begin natural regeneration, and shrub and tree species were introduced by sowing and planting. Differences in survival and growth of the introduced species and the natural regeneration, in relation to canopy gaps dimensions are shown. Sowings below gaps with widths less than one fourth of the stand height turned out to be useless. Gap widths greater than one third of the stand height have permitted acceptable growth of some of the introduced species, a few of them, e.g. Coronilla juncea L, are begining to regenerate. Planted seedlings have presented high percentajes of mortality and very low growth. Viable regeneration of Pinus halepensis has been limited to gaps with diameter greater than stand height. Analogous results obtained in plots on Pinus pinaster stands are also referred.