Moderate Thinning Research Articles

Airborne Laser Scanning Cartography of On-Site Carbon Stocks as a Basis for the Silviculture of Pinus Halepensis Plantations

Forest managers are interested in forest-monitoring strategies using low density Airborne Laser Scanning (ALS). However, little research has used ALS to estimate soil organic carbon (SOC) as a criterion for operational thinning. Our objective was to compare three different thinning intensities in terms of the on-site C stock after 13 years (2004–2017) and to develop models of biomass (Wt, Mg ha−1) and SOC (Mg ha−1) in Pinus halepensis forest, based on low density ALS in southern Spain. ALS was performed for the area and stand metrics were measured within 83 plots. Non-parametric kNN models were developed to estimate Wt and SOC. The overall C stock was significantly higher in plots subjected to heavy or moderate thinning (101.17 Mg ha−1 and 100.94 Mg ha−1, respectively) than in the control plots (91.83 Mg ha−1). The best Wt and SOC models provided R2 values of 0.82 (Wt, MSNPP) and 0.82 (SOC-S10, RAW). The study area will be able to stock 134,850 Mg of C under a non-intervention scenario and 157,958 Mg of C under the heavy thinning scenario. High-resolution cartography of the predicted C stock is useful for silvicultural planning and may be used for proper management to increase C sequestration in dry P. halepensis forests.

Dynamics of nitrogen and active nitrogen components across seasons under varying stand densities in a Larix principis-rupprechtii (Pinaceae) plantation.

Changes in the concentration of soil nitrogen (N) or its components may directly affect ecosystem functioning in forestry. Thinning of forest stands, a widely used forestry management practice, may transform soil nutrients directly by altering the soil environment, or indirectly by changing above- or belowground plant biomass. The study objectives were to determine how tree stem density affects the soil N pool and what mechanisms drive any potential changes. In this study, N and its active components were measured in the soil of a Larix principis-rupprechtii plantation across two full growing seasons, in 12 (25 × 25 m) plots: (low thinning, removal of 15% of the trees, three plot repetitions), moderate thinning (MT) (35% removal) and heavy thinning (HT) (50% removal) and no thinning control. Environmental indices, like the light condition, soil respiration, soil temperatures, and prescription, were measured in the plots also. Results indicated that soil total nitrogen (STN) was affected by tree stem density adjustments in the short-term; STN generally increased with decreasing tree stem density, reaching its highest concentration in the MT treatment before decreasing in HT. This pattern was echoed by the DON/STN ratio dissolved organic nitrogen (DON) under MT. A lower DON/STN was measured across the seasons. Microbial biomass nitrogen (MBN) and the SOC/STN (soil organic carbon (SOC)) ratio and density treatments influenced MBN concentration and inhibited SOC/STN. MT tended to accumulate more STN, produce lower DON/STN and had a generally higher microbial activity, which may be partly ascribed to the higher MBN value, MBN/STN ratio and lower DON/STN. The water conditions (soil moisture), light and soil temperatures could partly be responsible for the N pool dynamic in the different density treatments.

The impact of low body mass index on postoperative outcomes in pancreatectomy patients: a retrospective analysis of Japanese administrative data.

To comparatively examine in-hospital mortality among different underweight body mass index (BMI) categories in pancreatic cancer patients after pancreatectomy in Japan. We conducted a large-scale multi-center retrospective cohort study of adult patients with pancreatic cancer who underwent pancreatectomy between April 1, 2010 and March 31, 2016. Patients were classified according to BMI as follows: normal BMI (18.50-24.99kg/m2), mild thinness (17.00-18.49kg/m2), moderate thinness (16.00-16.99kg/m2), and severe thinness (< 16.00kg/m2). A multivariable logistic regression analysis was performed with in-hospital mortality as the dependent variable and BMI groups as the main independent variable of interest. We analyzed 6173 patients from 332 hospitals. The results showed that the severe thinness group had a longer postoperative hospital stay (34.4 ± 25.6 days) and higher incidence of postoperative pneumonia (5.5%) than the other groups. The generalized estimating equations accounted for patient demographics, surgical procedure, anesthetic technique, activities of daily living score, and Charlson comorbidity index as covariates. Relative to the normal BMI group, the odds ratios for in-hospital mortality were 0.57 (95% confidence interval: 0.26-1.24; P = 0.16) in the mild thinness group, 1.49 (0.64-3.48; P = 0.36) in the moderate thinness group, and 2.54 (1.05-6.08; P = 0.04) in the severe thinness group. Severe thinness was significantly associated with a higher risk of mortality, and extremely low BMI should be considered a risk factor in pancreatectomy patients.

Moderate thinning increases soil organic carbon in Larix principis-rupprechtii (Pinaceae) plantations

Forest thinning management practices such as thinning play a major role in the process of soil organic carbon (SOC) sequestration, however, the mechanism for SOC variations is still unclear. The objectives of this study were to estimate SOC stock and its active chemical components following a short term density adjustment of stand woods. Three treatments, low intensity thinning (removal of 15% of the trees, three 25 ∗ 25 m repeated plots), moderate thinning (30% removal), and heavy intensive thinning (50% removal) were compared to control plots with no thinning three years before sampling of soil carbon composition. A number of carbon components (i.e. SOC; soil total nitrogen, TN; permanganate oxidizable C, POXC; dissolved organic carbon, DOC; microbial biomass carbon, MBC) were measured in five soil layers within the Larix principis-rupprechtii plantation throughout the growing seasons of 2015 and 2016. Results indicated both SOC content and its active component, POXC content, were maximized under the moderate density adjustment (p < 0.01). Density adjustment significantly affected POXC/SOC ratio (p < 0.001), with maximum POXC content per unit SOC content also under moderate density adjustment. However, density adjustment hardly had any impact on DOC or MBC, both of which showed more obvious seasonal dynamics than SOC, TN and POXC. Summer affected SOC storage by altering the POXC, TN and MBC. Our results suggest that effects of density adjustment on POXC drive variation in SOC.

Effect of thinning intensity on tree growth and temporal variation of seed and cone production in a Pinus koraiensis plantation

Thinning of Korean pine (Pinus koraiensis Sieb. et Zucc.) is used to facilitate timber and cone production. The present study in Northeast China investigated the effects of thinning intensity on individual tree growth, temporal variation in cone yield, and seed quality in Korean pine plantation. In 2005, five thinning intensity levels (none, extreme, heavy, moderate and light) were set in 15 permanent plots in a 32-year-old Korean pine plantation at Mengjiagang Forest Farm, Jiamusi City, Heilongjiang Province. We recorded tree growth and seed cone production from 2013 to 2016, i.e., from 8 to 11 years after thinning. Except for height growth, thinning increased tree growth (diameter at breast height and crown size) and improved cone yield. The extreme thinning treatment (to 300 trees per hectare) resulted in the largest tree diameter, tree volume, crown size and 4-year cone production per tree. The highest cone yield per tree in the mast year (2014) was observed when stands were thinned to 500 trees per hectare (heavy thinning). Although the best cone and seed quality and the largest cone and seed mass per tree were recorded in the heavily thinned stand, no significant differences were found between heavy and moderate thinning stands (750 trees per hectare). At the stand level, the moderately thinned stand had the highest basal area, stock volume and seed cone production per stand. Our results suggest that thinning to 750 trees per hectare will improve timber and cone productivity in 40-year-old P. koraiensis stands.

Effects of different thinning intensities on soil carbon storage in Pinus laricio forest of Apennine South Italy

This study investigated, in a Pinus laricio forest of south Italy, how systematic thinning of different intensities (intense thinning, T45; moderate thinning, T25; clear cut, CC; and no thinning, T0) affected soil biological properties, organic matter trend and carbon (C) storage in soil and plants. Soil carbon content and carbon/nitrogen (C/N) ratio were significantly higher in the T45 than in control, T25 and CC. Under T45, the soils had also the highest enzymatic activities, microbial biomass carbon (MBC) and colonies of fungi and bacteria. The humification parameters (humification ratio, HR; the degree of humification, DH; humification index, HI) indicated T45 as the best silvicultural practice-approach method to manage Pinus laricio forest for increasing soil carbon storage. The dendrometric parameters evidenced that T45 caused the greatest increment in wood growth (diameter and height), showing that the positive effect of the intense systematic thinning (T45) on the mechanical stability of plantation was related to the ability of trees to accumulate large amounts of carbon in their wood tissues. These data were confirmed by wood density value that was the highest in pine trees under the T45. This study showed that in Pinus laricio forest under T45 C stock increased in soil and plant, already 4 years after thinning.

Density reduction in loblolly pine (Pinus taeda L.) stands to increase tree C assimilation: an approach with the dual δ13C and δ18O isotope signatures in needles

In the context of increasing droughts related to climate change, our results showed that heavy thinning and/or very low initial planting density can increase CO 2 assimilation rate in needles, and may be used as a short-term management strategy for loblolly pine plantation across sites prone to drought. The dry summer of 2013 provided us an opportunity to understand the CO2 assimilation rate and stomatal conductance after density manipulation treatments using the dual isotope (δ13C and δ18O) signatures in needles of planted loblolly pine (Pinus taeda L.) trees in the southeastern USA. To our knowledge, this is the first study using the dual isotope approach to examine the physiological response of loblolly pine trees, one of the most widely planted tree species in the world, to stand density manipulation treatments (i.e., thinning intensity and planting density). In 2001–2003, trees were planted with five different planting densities, 494, 1111, 1729, 2346, and 2964 trees ha−1 at three sites. In 2009–2011, two thinning treatments (none and moderate thinning) were applied in the 1111 trees ha−1 plots, whereas three treatments (none, light and heavy thinning) were applied in the 1729 trees ha−1 plots. Response variables (specific leaf area (SLA), foliar N, δ13C and δ18O) were measured in February 2014. SLA was lower, while δ18O was higher in the 494 trees ha−1 plots than the 2964 trees ha−1 plots without thinning. In plots planted to 1729 trees ha−1 SLA was lower, while δ13C and δ18O were higher following heavy thinning than in the unthinned control. These responses plus increased crown length, DBH, and height following heavy thinning may reflect an increased tree-level CO2 assimilation rate. Our results showed that heavy thinning and/or very low initial planting density can be used as a short-term management strategy for loblolly pine plantation across sites prone to drought.

The Crop Load Affects Brown Rot Progression in Fruit Orchards: High Fruit Densities Facilitate Fruit Exposure to Spores but Reduce the Infection Rate by Decreasing Fruit Growth and Cuticle Cracking

Brown rot, triggered by Monilinia spp., causes significant economic losses in fruit crop and it is mainly controlled by chemicals with inherent environmental costs. Controlling brown rot spreading by diminishing fruit susceptibility to the disease, via sustainable cultural practices, is a promising approach. In a two years experiment (2014-2015) on a peach (Prunus persica) orchard, we controlled fruit growth rates by varying the fruit load. Fruit thinning practices enhanced the fruit growth and laboratory analyses showed that, in both 2014 and 2015 samples, fast growing fruits were more susceptible to infection when in contact with conidia suspension of Monilinia laxa. In the field, brown rot infection took place in 2014 and not in 2015. In 2014, trees subject to moderate thinning intensities had the highest brown rot incidence. We argue that this is due to the fact that, for null thinning, slow growing fruits are less susceptible to the infection while, for intense thinning, even if faster growing fruits are more susceptible to infection, the lower fruits density reduces per-contact probability of infection. We compared meteorological data of 2014 and 2015 and we argue that brown rot did not spread in 2015 due to an absence of favorable conditions, summarized as the number of rainy days with mean temperature between 22 and 26 °C , in the period of fruit susceptibility.

间伐和改变凋落物输入对华北落叶松人工林土壤呼吸的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 间伐和改变凋落物输入对华北落叶松人工林土壤呼吸的影响 DOI: 10.5846/stxb201703160449 作者: 作者单位: 北京林业大学林学院 北京 100083,北京林业大学林学院 北京 100083,北京林业大学林学院 北京 100083,北京林业大学林学院 北京 100083,北京林业大学林学院 北京 100083,北京林业大学林学院 北京 100083 作者简介: 通讯作者: 中图分类号: 基金项目: 国家重点研发计划（2016YFD0600205） Thinning treatment and litterfall changes influence soil respiration in a Larix principis-rupprechtii plantation Author: Affiliation: Forestry College of Beijing Forestry University,Forestry College of Beijing Forestry University,Forestry College of Beijing Forestry University,Forestry College of Beijing Forestry University,Forestry College of Beijing Forestry University,Forestry College of Beijing Forestry University Fund Project: National Key R&D Plan 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:作为森林生态系统的第二大碳通量，土壤呼吸在全球碳循环和气候变化中发挥着重要作用。通过探究土壤呼吸对间伐和改变凋落物的响应规律以及响应之间的联系，能够为准确评价森林碳循环提供依据。针对不同强度（对照、轻度、中度、重度）间伐后的华北落叶松人工林，2016年5月至10月采用LI-8100土壤碳通量测量系统对其原状、凋落物去除、凋落物加倍的土壤呼吸进行观测。结果表明：土壤呼吸在生长季的8月份达到最高值，呈现出明显的季节动态。不同林分间伐处理下，中度间伐显著促进了土壤呼吸，使平均土壤呼吸速率升高了15.66%，轻度间伐和重度间伐对土壤呼吸的影响不显著；不同凋落物处理下，去除凋落物使平均土壤呼吸速率降低了40.16%，加倍凋落物使平均土壤呼吸速率升高了16.06%。中度间伐使土壤呼吸生长季通量增加了55.06 g C/m2；去除凋落物使土壤呼吸生长季通量减少了153.48 g C/m2，加倍凋落物使土壤呼吸生长季通量增加了79.87 g C/m2。土壤呼吸速率与土壤温度呈显著指数相关，而与土壤湿度无显著相关。不同林分间伐处理下，土壤呼吸的温度敏感性指数（Q10）为2.36-3.46，轻度间伐下Q10值最高；凋落物去除和加倍均降低了土壤呼吸的温度敏感性。土壤温湿度对土壤呼吸存在着显著影响，能够解释土壤呼吸28.7%-62.3%的季节变化。研究结果表明间伐和凋落物处理对华北落叶松人工林土壤CO2释放的影响表现出一定的交互作用，中度间伐和加倍凋落物的交互作用对土壤呼吸的促进作用显著大于单一因子。可见，间伐作业通过改变土壤微环境和凋落物量，对土壤呼吸以及森林生态系统碳循环产生着重要影响。 Abstract:Soil respiration (Rs), the second largest site of carbon flow in the forest ecosystem carbon budget, plays an important role in the global carbon (C) cycle and climate change. Understanding the effects of forest management practices (e.g. thinning) on Rs is crucial for the accurate estimation of forest carbon cycling. Simultaneously, aboveground litter management practices (removal, addition, and so on) can also influence Rs. However, little is known about the response of Rs to thinning and its relationship with the changes in litter production induced by thinning. We aimed to quantify the response of Rs rate to different thinning intensities and to explore the relationships between Rs and soil temperature and moisture as a result of different litter management practices. A thinning manipulation experiment was conducted in a Larix principis-rupprechtii plantation in Shanxi province, China, with the following treatments:heavy thinning, moderate thinning, low thinning and no thinning. In addition, three treatments-litterfall removal, litter addition and normal litterfall-were applied to analyze the relationship between differences in litter input and Rs. Rates of soil respiration were measured twice a month using the LI-8100 Automated Soil CO2 Flux System from May to October 2016, while soil temperature and moisture at a depth of 5 cm were measured using temperature and moisture probes and data loggers. A significant difference was noted in Rs among the different thinning treatments (P < 0.05). Clear monthly variations in Rs were noted in the growing season, and Rs reached its peak value in August. Overall, moderate thinning increased Rs rate during the growing season by 15.7% from that of the no-thinning treatment. During the growing season, the Rs rate was lower by 40.16% with litterfall removal than that of normal litterfall; however, Rs rate was higher by 16.06% with litter addition than that of normal litterfall. Moderate thinning increased accumulative Rs by 55.06 g C/m2 during the growing season. Under litter removal conditions, accumulative Rs decreased by 153.48 g C/m2 during the growing season, while accumulative Rs increased with litter addition by 79.87 g C/m2. During the growing season, Rs exhibited significant exponential relationships with soil temperature, while there were no significant differences in soil moisture among the various treatments. Temperature sensitivity (Q10) values of Rs ranged from 2.36 to 3.46 in the various thinning intensities, with the highest Q10 value in the low thinning stand. The Q10 value were lower with the litter removal and litter addition treatments than those of normal litterfall. The interaction of soil temperature and moisture had a significant effect on Rs. The best fitting model with temperature and moisture explained 28%-62% of the variation in Rs. The results indicated that the interaction between thinning treatments and litter changes has a significant effect on the Rs in L. principis-rupprechtii plantations. The compound effect of moderate thinning and litter addition on Rs is significantly greater than that of any single factor. In conclusion, thinning played a considerable role in altering Rs and carbon cycle in forest ecosystems by influencing the soil micro-environment and litter production rates. 参考文献 相似文献 引证文献

Growth dynamics, climate sensitivity and water use efficiency in pure vs. mixed pine and beech stands in Trentino (Italy)

Abstract Understanding to what extent species mixtures modify the growth of trees and their responses to climate, in comparison with pure stands, is important to support forest adaptation and mitigation strategies. In this sense, information stored in tree rings can be useful to evaluate whether the positive relationship between species diversity and tree productivity holds true under disturbance (e.g., drought). This paper aimed at assessing (i) how radial growth of trees responded to local variation in climate patterns (Standardised Precipitation-Evapotranspiration Index; SPEI), and (ii) whether there was a relationship with intrinsic water use efficiency (WUEi) and tree-ring δ18O in two important tree species, occurring in pure and mixed forest stands. Three sites with similar topographic and pedo-climatic conditions were identified in a single location in the Italian Alps. The first two are characterized by pure stands, respectively dominated by European beech (Fagus sylvatica L.) and Scots pine (Pinus sylvestris L.). The third site refers to a mixed stand of both previous species. In particular, in order to assess the annual changes in WUEi, we analysed δ13C in tree rings. The influence of the stomatal conductance was also investigated through δ18O. Our results indicated that: (i) Basal Area Increments (BAI) consistently increased in all stands except for the pure Scots pine stand, in the 1994–2003 period; (ii) SPEI highlighted a drought period between 1991 and 2007 (62.2% of the average precipitation); and (iii) the WUEi values were generally higher in pure than in mixed stands, especially for European beech. The divergence between BAI and SPEI values in the 1990s and early 2000s could be a consequence of moderate thinning. We conclude that past forest management (namely thinning) can be more influential on tree growth than current climatic oscillations.

Thinness in young schoolchildren in Serbia: another case of the double burden of malnutrition?

Thinness is rarely highlighted or regularly monitored among children in developed countries although it may be rather frequent and pose a significant risk to children's health. We aimed to describe the prevalence of mild, moderate and severe thinness among young Serbian schoolchildren. Cross-sectional study of schoolchildren aged 6-9 years. Children were assessed for weight, height and BMI as part of the WHO European Childhood Obesity Surveillance Initiative in Serbia. Thinness grades were defined as gender- and age-specific cut-offs for BMI according to the International Obesity Task Force criteria. Serbia, September to November 2015. Students (n 4861) in grades 2 and 3 (6-9 years, 2397 girls). Overall prevalence of thinness in Serbian schoolchildren was 9·6 %. Mild thinness was clearly the largest category with a prevalence of 7·6 %, moderate thinness was present in 1·7 % of children and severe thinness was found in 0·3 % of children. OR indicated a significant risk of being thin for girls (1·44 times higher compared with boys) and children attending schools with no health-focused educational programme (1·57 times more likely to be thin than peers enrolled in schools with such programmes). In addition, OR for thinness tended to be 1·23 times higher in children living in an economically disadvantaged region of Serbia (P=0·06). A rather high prevalence of thinness highlights this malnutrition disorder as an emerging health issue that should trigger public health policies to tackle thinness, especially in girls of young age and children living in economically disadvantaged areas.

Thinning increases tree growth by delaying drought-induced growth cessation in a Mediterranean evergreen oak coppice

Abstract The Mediterranean evergreen oak coppices of Southern Europe are increasingly vulnerable to drought because of both the ongoing climate change that increases drought length and intensity, and the lack of forest management that induces a structural aging of the stands. Decreasing stand density through thinning has been widely regarded as a means to improve the resistance of evergreen oak forests to climate change by decreasing the competition for water amongst the remaining stems. Data from a 30-years thinning experiment, that includes a control and four thinning intensity treatments (from 25% to 80% of basal area removed), in a coppiced holm oak (Quercus ilex L.) forest of southern France, was used to quantify the effects of thinning on stem growth. Building on the ‘sink limitation’ paradigm, which proposes that tree growth is controlled by phenology and climatic constraints and decoupled from carbon assimilation, we investigated if the effect of thinning on stem growth was explained by a delayed drought-induced growth cessation. Using a water balance model, we simulated the date of drought-induced growth cessation, previously found to correspond to the day of the year when water potential drops below a threshold of −1.1 MPa, and used it to predict growth in the different treatments of the thinning experiment. Thinning increased long-term growth at the stem level but decreased the wood biomass at the stand level. Decreasing stem density, and hence the leaf area index, was simulated to delay the date of drought-induced growth cessation. A growth model based on the date of growth cessation explained 85% of the effect of thinning on stem growth over the 30-year period of the study, and 95% for the first five years after thinning. The canopy density for which the effect of thinning is the most beneficial was found to maximize the growth duration without lifting completely the water limitation in summer. Moderate thinning had a sustained beneficial effect on the growth of all stem size classes, whereas stronger thinning intensities increased the size asymmetry of competition and their overall effect dropped faster. Our simple predictive model based on the simulation of the water balance as a function of stand density opens the way to providing management guidelines for the optimization of tree density as a function of water limitation in Mediterranean evergreen woodlands.

Damage evolution and ductile fracture prediction during tube spinning of titanium alloy

In order to analyze and control surface crack during tube spinning of titanium alloy, six ductile fracture criteria (DFCs) were incorporated into the finite element software (ABAQUS) to simulate the damage evolution in the tube spinning process under various thinning rates. For improving the prediction accuracy of damage evolution during tube spinning, the valid damage strain was proposed to eliminate or diminish the strain fluctuation caused by the ALE adaptive meshing technique. Through analyzing the influence of the equivalent plastic strain, stress state and the principal stresses on the damage accumulation, the mechanisms of surface cracks were revealed. The results show that only the McClintock model predicted that the crack in tube spinning of Ti–15–3 alloy could be eliminated under moderate thinning rates, while lower or higher thinning rates may induce cracking on the tube surface, which was consistent with the experimental results. For the outer layer, as the thinning rate increased, the increasing equivalent plastic strain and tensile principal stresses contributed to the damage accumulation for all the DFCs studied in present research. For the inner layer under moderate thinning rates, the compressive axial and tangential stresses slowed down the damage accumulation, leading to the occurrence of the safe zone of thinning rate (∼20–30%) without surface crack during tube spinning of Ti–15–3 alloy.

Acoustic evaluation of wood quality with a non-destructive method in standing trees: a first survey in Italy

Abstract: Research and development efforts are currently underway worldwide to examine the potential use of a wide range of non-destructive technologies (NDT) for evaluating wood and wood-based materials, from the assessment of standing trees to in-place structures. For this purpose, acoustic velocity by the Fakopp time of flight (TOF) tool was used to estimate the influence of four thinning treatments performed in Southern Italy. The objective of the study was to determine if the effects of silvicultural practices on wood quality can be identified using acoustic measurement to assess the MOEd of standing trees with non-destructive method in Calabrian pine (Pinus nigra Arnold subsp. calabrica). Four hundred and fifty standing trees from four sites were non-destructively tested using a time-of-flight acoustic wave technique. The thinning trials were conducted on 60-year-old plantations of Calabrian pine in four plots under different treatments: Control (T), light thinning (A), intermediate thinning (B) and heavy thinning (C). Statistical analysis demonstrated significant stress wave time differences between the stands with moderate thinning (A and B) and those with heavy thinning (C). The results showed that tree diameter has significant influence on acoustic wave measurements and a valid relationship exists between diameter at breast height and tree velocity. The results of these studies proved that the stress wave technique can be successfully applied on standing trees.

Effect of forest stand management on species composition, structural diversity, and productivity in the temperate zone of Europe

Forests in Central Europe have been used since centuries and were systematically changed by silvicultural practices since the late 1700s. Focusing on possible biodiversity losses, forest stand management primarily impacts on the biodiversity attributes ‘composition, structure and functioning’ that are interlinked and incorporate different organizational and spatial ecosystem levels. Forest stand management can manipulate tree species diversity, which in turn affects stand structure and finally leads to changes in forest functions and services. We used meta-analyses to review 49 papers with 197 comparisons on compositional and structural diversity between unmanaged and managed forests as well as 53 comparisons of biomass productivity between mixed and monoculture forests throughout the temperate biome of Europe. Besides management impacts, for species and structural comparisons, we took time since abandonment of forest stand management into consideration when dealing with unmanaged forests. For species richness and diversity, we could not detect significant management effects; no significant influences of time since abandonment of management could be identified either. Structural attributes partly revealed considerable responses to forest stand management. Importantly, deadwood quantity, the number of microhabitats, and tree size diversity were reduced by forest stand management, while no effect was found for stand basal area and the number of living trees. Some of these effects become more pronounced with increasing time since abandonment. Forest productivity was significantly enhanced by regular moderate thinning compared with untreated stands and by tree species mixing compared with monospecific stands. Based on these results, we discuss the role of direct and indirect silvicultural effects, interactions between biodiversity components, the problem of defining the unmanaged reference state, and perspectives for forest stand management in practice.

Temporal variability in soil moisture after thinning in semi-arid Picea crassifolia plantations in northwestern China

Soil moisture controls the functioning of semi-arid ecosystems. The response of soil moisture to forest stand thinning determines planting density and sustainability of forest development. However, consequences of stand thinning are poorly known in semi-arid ecosystems of the Qilian Mountains of China. We investigated long-term effects of three thinning intensities in Picea crassifolia plantations on soil hydrological responses and soil moisture dynamics at 10, 20, 40, 60, and 80cm depths, and compared them to those of a natural Picea crassifolia forest.Results revealed that soil hydrological response may be temporarily modified by thinning according to changes in canopy structure, precipitation properties, and antecedent soil moisture conditions. Soil moisture in natural forest rapidly infiltrated into deep soil, which greatly improved the efficiency of precipitation use. Thinning significantly increased the capacity for soil infiltration, and moderate thinning intensity may be conducive to deep soil-water recharge. Soil moisture content changed drastically after thinning, with a significant decrease near-surface (10cm), and a significant increase in sub-surface (60 and 80cm) soil. High planting density was the main cause of severe soil moisture deficits in the long-term, but it could be mitigated by 20–40% thinning (∼3139 trees ha−1). Changes in precipitation patterns that include larger but less frequent rainfall events during the growing season will benefit the growth of vegetation planted at high densities in this semi-arid region.

Effects of Thinning on Soil Organic Carbon Fractions and Soil Properties in Cunninghamia lanceolata Stands in Eastern China

Soil organic carbon (SOC) fractions, along with soil properties, are greatly affected by forest management. In this study, three thinning treatments: control (conventional management mode), moderate thinning intensity and heavy thinning intensity, were applied in Chinese fir (Cunninghamia lanceolata) plantations in eastern China. The dissolved organic carbon (DOC), soil light fraction organic carbon (LFOC) and heavy fraction organic carbon (HFOC), total SOC, DOC/SOC and LFOC/HFOC were not affected by thinning treatments. In the heavy thinning treatment, soil bulk density decreased, and soil water holding capacity and porosity increased in the topsoil layers (0–10 cm and 10–20 cm). Total nitrogen, hydrolysable nitrogen, and zinc concentrations increased in the topsoil layers (0–20 cm) in the heavy thinning treatment compared to the control treatment, while the available potassium concentration reduced. The moderate thinning treatment had little effect on the soil physical and chemical properties. Moreover, the variation of SOC fractions was strongly correlated to soil physical and chemical properties. These results suggest that thinning has little effect on the total SOC and its fractions in one rotation of Chinese fir tree in eastern China. In contrast, however, results also suggest that thinning has a positive effect on soil quality, to a certain extent.

Size Matters a Lot: Drought-Affected Italian Oaks Are Smaller and Show Lower Growth Prior to Tree Death.

Hydraulic theory suggests that tall trees are at greater risk of drought-triggered death caused by hydraulic failure than small trees. In addition the drop in growth, observed in several tree species prior to death, is often interpreted as an early-warning signal of impending death. We test these hypotheses by comparing size, growth, and wood-anatomy patterns of living and now-dead trees in two Italian oak forests showing recent mortality episodes. The mortality probability of trees is modeled as a function of recent growth and tree size. Drift-diffusion-jump (DDJ) metrics are used to detect early-warning signals. We found that the tallest trees of the anisohydric Italian oak better survived drought contrary to what was predicted by the theory. Dead trees were characterized by a lower height and radial-growth trend than living trees in both study sites. The growth reduction of now-dead trees started about 10 years prior to their death and after two severe spring droughts during the early 2000s. This critical transition in growth was detected by DDJ metrics in the most affected site. Dead trees were also more sensitive to drought stress in this site indicating different susceptibility to water shortage between trees. Dead trees did not form earlywood vessels with smaller lumen diameter than surviving trees but tended to form wider latewood vessels with a higher percentage of vessel area. Since living and dead trees showed similar competition we did not expect that moderate thinning and a reduction in tree density would increase the short-term survival probability of trees.

Birth Order, Father's Occupation and Family Size are Strongly Associated with Thinness Among Bengalee Adolescent Girls of Darjeeling District, West Bengal (India)

Introduction: Undernutrition is a major issue in the developing countries such as India. The country has the largest adolescent population in the world and one of the primary focuses of nutritional assessment among them is undernutrition. The present cross-sectional study tries to determine the prevalence of thinness among adolescent girls of Darjeeling district using thinness (BMI-for-age) and to ascertain the effects of different socio-economic and demographic variables on the same.Material and methods: The study was carried out among 387 school-going adolescent girls aged 9-14 years belonging to the Bengalee Hindu caste populations (BHCP). The prevalence of thinness was assessed using recently proposed international BMI-for-age cut-offs of Cole et al.Results: The prevalence of overall thinness was 23.77%. The distribution of mild (Grade I), moderate (Grade II), and severe (Grade III) thinness were 17.31%, 4.39% and 2.07%, respectively. The results of the binary logistic regression analysis showed that birth order, family size and father’s occupation were significantly associated with overall prevalence of thinness (p&lt;0.05).Conclusion: The proper dissemination of awareness related to nutritional requirement, food habit, and appropriate dietary habit would be helpful to reduce the prevalence of thinness.J Nepal Paediatr Soc 2016;36(2):115-120

Modeling the Chronic Loss of Optic Nerve Axons and the Effects on the Retinal Nerve Fiber Layer Structure in Primary Disorder of Myelin.

PurposeWe determined whether the chronic lack of optic nerve myelination and subsequent axon loss is associated with optical coherence tomography (OCT) changes in the retinal nerve fiber layer (RNFL), and whether this models what occurs in multiple sclerosis (MS) and confers its use as a surrogate marker for axon degeneration.MethodsUsing an animal model of Pelizaeus-Merzbacher disease (shp) bilateral longitudinal measurements of the peripapillary RNFL (spectral-domain OCT), electroretinograms (ERG), and visual evoked potentials (VEP) were performed in affected and control animals from 5 months to 2 years and in individual animals at single time points. Light and electron microscopy of the optic nerve and retina and histomorphometric measurements of the RNFL were compared to OCT data.ResultsOf the shp animals, 17% had an average reduction of OCT RNFL thickness on the superior retinal quadrant compared to controls (P < 0.05). Electroretinograms showed normal photopic A- and B-waves but flash VEPs were disorganized in shp animals. Morphologically, the shp retinas and optic nerves revealed significant RNFL thinning (P < 0.001) without retinal ganglion cell (RGC) loss, decrease total and relative retinal axonal area, and loss of optic nerve axons. There was strong positive correlation between OCT and morphometric RNFL thickness measurements (r = 0.878, P = 0.004).ConclusionThe loss of optic nerve axons demonstrated in the shp model resulted in moderate thinning of the RNFL confirmed by OCT and histology. These results indicate that OCT-derived RNFL measurement can be a useful surrogate biomarker of optic nerve axon loss and potentially disease progression in demyelinating diseases.