scholarly journals Development of Downy Birch (Betula pubescens Ehrh.) Coppice Stands during Nine Years

Forests ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 958
Author(s):  
Jyrki Hytönen
Keyword(s):  
Low Cost ◽  
Stand Age ◽  
Age Classes ◽  
Annual Increment ◽  
Class A ◽  
Age Class ◽  
Growing Seasons ◽  
Downy Birch ◽  
The Mean ◽  
Betula Pubescens Ehrh

Growing of dense, naturally regenerated downy birch stands using rotations of 24–26 years has been shown to be profitable. Coppicing would be a low-cost regeneration method, however, knowledge on the development of birch coppices is scarce. The height, stem number, and biomass development of sprouts originating from six clearcut stands in three age classes (A: 10–12 years, B: 15–16 years, C: 22–24 years) located in northern Finland was studied. Equations for estimating the aboveground biomass from height were developed for sprouts. The number of sprouts, and their height and biomass were measured annually during nine growing seasons. In addition, sprout damage was assessed. The number of sprouts per hectare was highest in the youngest age class (A) throughout the study period, even though the decrease in the number of stems due to self-thinning was also fastest (from 591,000 sprouts per ha to 105,000 sprouts per ha). The stand age class did not have an effect on either the mean (2.7 m) or dominant height (5.4 m) of birch sprouts. The total leafless above-ground biomass, the mean annual increment (MAI), and the current annual increment (CAI) were highest in the youngest stand age class (A) and lowest in the oldest age class (C). After 9 years, the biomass in the oldest age class was 15.1 Mg ha−1 and 31.1 Mg ha−1 in the youngest age class. During the first six years, the biomass of the sprouts correlated with the number of stumps. A higher number of stumps produced more sprouts and biomass in the first years. However, due to faster self-thinning in the densest stands and higher mass of average sprout in the oldest stands, the correlation between the number of stumps and biomass decreased with the increase of age so that it was no longer significant in years 7, 8, and 9. In the older stand age classes, the MAI increased with the increase of the age of sprouts. The CAI varied considerably between the study years. The study showed that due to coppice vigor, growth of the birch sprouts can be high.

scholarly journals Slenderness of trees in black locust stands

2018 ◽  
Vol 79 (2) ◽  
pp. 113-117
Author(s):  
Szymon Bijak ◽  
Katarzyna Orzoł
Keyword(s):  
Standard Deviation ◽  
Black Locust ◽  
Robinia Pseudoacacia ◽  
Habitat Type ◽  
Stand Age ◽  
Age Classes ◽  
Breast Height ◽  
Age Class ◽  
Crown Length ◽  
Research Material

Abstract This paper investigates the slenderness of black locust (Robinia pseudoacacia) trees in relation to the biosocial status of the trees, stand age class, crown parameters and habitat type. The research material was collected on 35 research plots in the Sława Śląska, Sulechów and Głogów forest districts in western Poland and comprises 1058 trees. For each tree, we measured height (h) as well as diameter at breast height (d) and determined its biosocial status (Kraft class), crown length (CL) and relative crown length (rCL). The age class and habitat type were assessed at the plot level. Because the obtained values for slenderness (s=h/d) diverged significantly from the normal distribution, we used Kruskal-Wallis and Mann-Whitney tests to investigate the influence of the above-mentioned parameters on the h/d ratio. Black locust slenderness ranged from 0.31 to 1.95 with an average of 0.91 (standard deviation 0.24). It furthermore differed significantly between Kraft classes (the higher the biosocial status, the lower the slenderness) and age classes (the older the trees, the lower their slenderness). We also found a significant effect of the habitat type (in oligotrophic sites trees formed more slender trunks than in mesotrophic sites) and crown parameters on the h/d ratio (decreasing with increasing crown length and relative crown length). The obtained results suggest that the slenderness of black locust does not differ substantially from native broadleaved trees in Poland.

Stand age influence on litter mass of Pinus nigra plantations on dolomite hills in Hungary

2006 ◽  
Vol 84 (3) ◽  
pp. 363-370 ◽  
Author(s):  
Imre Cseresnyés ◽  
Péter Csontos ◽  
Erika Bózsing
Keyword(s):  
Sampling Site ◽  
Pinus Nigra ◽  
Economic Problem ◽  
Slope Aspect ◽  
Stand Age ◽  
Age Classes ◽  
Litter Mass ◽  
Age Class ◽  
Increased Risk ◽  
Pine Stands

In Hungary, plantations of Pinus nigra Arn. (Austrian pine) involve large areas of dolomite rock grasslands and have caused the impoverishment or local extinction of the original flora. In addition to these conservation concerns, an important economic problem is the flammability of these forests. Fire risk depends on the amount of accumulated flammable organic components. Thus, the purpose of our research was to quantify the mass of litter accumulated in Austrian pine stands and to examine the correlation between litter mass, stand age, and slope aspect. Forty-eight sampling sites were selected with stand ages ranging from 21 to 108 years. Stands represented four age classes and three exposure types. At each sampling site, litter mass was determined in the following three fractions: needles, branches, and cones. The litter fractions showed their maximum quantities in age class 61–80 years (needles = 17 560 kg/ha, branches = 2764 kg/ha, and cones = 2960 kg/ha). For the needle litter, a significant increase with age was detected through the age classes of 21–40, 41–60, and 61–80 years, and then a significant decrease occurred in stands above 80 years. In the case of branch litter, the age-dependent increase was again significant to its maximum quantity, but the decrease in old stands proved to be insignificant. With cone litter, age dependence could not be detected. Exposure of the stands had no effect on the quantities of the three litter fractions. The amount of accumulated litter of Austrian pine stands many times exceed the litter quantity of the rock grasslands (the original vegetation prior to afforestation). Furthermore, it is two or three times higher than the amount of litter reported from native zonal forests of Hungary. Therefore, the Austrian pine stands are subjected to an increased risk of fire, especially in age class 61–80 years.

Paternal ages below or above 35 years old are associated with a different risk of schizophrenia in the offspring

2007 ◽  
Vol 22 (1) ◽  
pp. 22-26 ◽  
Author(s):  
M. Wohl ◽  
P. Gorwood
Keyword(s):  
Meta Analysis ◽  
Paternal Age ◽  
Age Classes ◽  
Future Studies ◽  
Age Class ◽  
Increased Risk ◽  
The Mean ◽  
The Difference ◽  
Class Reference ◽  
Different Origins

AbstractBackgroundA link between older age of fatherhood and an increased risk of schizophrenia was detected in 1958. Since then, 10 studies attempted to replicate this result with different methods, on samples with different origins, using different age classes. Defining a cut-off at which the risk is significantly increased in the offspring could have an important impact on public health.MethodsA meta-analysis (Meta Win®) was performed, assessing the mean effect size for each age class, taking into account the difference in age class references, and the study design.ResultsAn increased risk is detected when paternal age is below 20 (compared to 20–24), over 35 (compared to below 35), 39 (compared to less than 30), and 54 years old (compared to less than 25). Interestingly, 35 years appears nevertheless to be the lowest cut-off where the OR is always above 1, whatever the age class reference, and the smallest value where offspring of fathers below or above this age have a significantly different risk of schizophrenia.ConclusionNo threshold can be precisely defined, but convergent elements indicate ages below or above 35 years. Using homogeneous age ranges in future studies could help to clarify a precise threshold.

A Test of the Relationship between Otolith Weight and Age for the Pilchard Sardinops neopilchardus

1991 ◽  
Vol 48 (1) ◽  
pp. 35-38 ◽  
Author(s):  
W. J. Fletcher
Keyword(s):  
Linear Relationship ◽  
Uniform Distribution ◽  
Frequency Distribution ◽  
Direct Relationship ◽  
Original Sample ◽  
Age Classes ◽  
Age Class ◽  
The Mean ◽  
The Relationship ◽  
Additional Sample

A sample of 60 fish revealed a near-linear relationship between otolith weight and the estimated age (determined from scale and otolith annuli) for the pilchard Sardinops neopilchardus, with little overlap of otolith weight values between age classes. In an additional sample of 612 fish where only otolith weight and length were measured, only two clear length modes were found, but five modes using an otolith weight frequency distribution could be distinguished. The means of the five modes were similar to that predicted from the mean weights for each age class in the original sample of 60 fish. These five modes were also present in a subsample of the 612 fish, chosen such that their lengths formed a uniform distribution (i.e. no modes). These results were consistent with a direct relationship between otolith weight and age, but further validation is required before this variable can be used as the sole determinant of age.

Age-class influences on feeding choices of free-ranging wild boars (Sus scrofa)

1989 ◽  
Vol 67 (11) ◽  
pp. 2792-2796 ◽  
Author(s):  
Maryse Dardaillon
Keyword(s):  
Diet Composition ◽  
Dietary Diversity ◽  
Age Classes ◽  
Wild Boars ◽  
Adult Age ◽  
Plant Parts ◽  
Age Class ◽  
The Mean ◽  
Feeding Choices ◽  
Free Ranging

Diet composition and diversity were compared between juvenile, yearling, and adult wild boars living in the Camargue region (southern France). Despite close similarity, feeding choices differed in various respects. First, the mean stomach content included a greater proportion of animal matter in subadults (juveniles and yearlings combined) than in adults. Secondly, yearlings and adults ate larger proportions of rice, and larger quantities by weight of underground plant parts, than juveniles. These differences were attributed to differing nutritional requirements according to age-class. On the other hand, greater diversity of feeding choices was found in juveniles than within the yearling and adult age-classes. It is argued that early experience of a broad dietary diversity is an advantage for coping with fluctuations in food availability such as those encountered in the Camargue.

scholarly journals Utility-Scale PV-Battery versus CSP-Thermal Storage in Morocco: Storage and Cost Effect under Penetration Scenarios

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4675
Author(s):  
Ayat-allah Bouramdane ◽  
Alexis Tantet ◽  
Philippe Drobinski
Keyword(s):  
Storage Capacity ◽  
Low Cost ◽  
Thermal Storage ◽  
Solar Pv ◽  
Storage Duration ◽  
Maximum Cost ◽  
Pv Inverter ◽  
The Mean ◽  
Mean Variance Portfolio ◽  
Utility Scale

In this study, we examine how Battery Storage (BES) and Thermal Storage (TES) combined with solar Photovoltaic (PV) and Concentrated Solar Power (CSP) technologies with an increased storage duration and rental cost together with diversification would influence the Moroccan mix and to what extent the variability (i.e., adequacy risk) can be reduced; this is done using recent (2013) cost data and under various penetration scenarios. To do this, we use MERRA-2 climate reanalysis to simulate hourly demand and capacity factors (CFs) of wind, solar PV and CSP without and with increasing storage capabilities—as defined by the CSP Solar Multiple (SM) and PV Inverter Loading Ratio (ILR). We adjust these time series to observations for the four Moroccan electrical zones over the year 2018. Our objective is to maximize the renewable (RE) penetration and minimize the imbalances between RE production and consumption considering three optimization strategies. We analyze mixes along Pareto fronts using the Mean-Variance Portfolio approach—implemented in the E4CLIM model—in which we add a maximum-cost constraint to take into account the different rental costs of wind, PV and CSP. We propose a method to calculate the rental cost of storage and production technologies taking into account the constraints on storage associated with the increase of SM and ILR in the added PV-BES and CSP-TES modules, keeping the mean solar CFs fixed. We perform some load bands-reduction diagnostics to assess the reliability benefits provided by each RE technology. We find that, at low penetrations, the maximum-cost budget is not reached because a small capacity is needed. The higher the ILR for PV, the larger the share of PV in the mix compared to wind and CSP without storage is removed completely. Between PV-BES and CSP-TES, the latter is preferred as it has larger storage capacity and thus stronger impact in reducing the adequacy risk. As additional BES are installed, more than TES, PV-BES is favored. At high penetrations, optimal mixes are impacted by cost, the more so as CSP (resp., PV) with high SM (resp., ILR) are installed. Wind is preferably installed due to its high mean CF compared to cost, followed by either PV-BES or CSP/CSP-TES. Scenarios without or with medium storage capacity favor CSP/CSP-TES, while high storage duration scenarios are dominated by low-cost PV-BES. However, scenarios ignoring the storage cost and constraints provide more weight to PV-BES whatever the penetration level. We also show that significant reduction of RE variability can only be achieved through geographical diversification. Technological complementarity may only help to reduce the variance when PV and CSP are both installed without or with a small amount of storage. However, the diversification effect is slightly smaller when the SM and ILR are increased and the covariances are reduced as well since mixes become less diversified.

scholarly journals Economic Burden of Colorectal Cancer: A Case of Fars, Iran

2021 ◽  
Vol 28 ◽  
pp. 107327482110099
Author(s):  
Abdosaleh Jafari ◽  
Peyman Mehdi Alamdarloo ◽  
Mehdi Dehghani ◽  
Peivand Bastani ◽  
Ramin Ravangard
Keyword(s):  
Colorectal Cancer ◽  
Economic Burden ◽  
Purchasing Power Parity ◽  
Annual Cost ◽  
Low Cost ◽  
Direct Costs ◽  
Fars Province ◽  
Power Parity ◽  
Medical Sciences ◽  
The Mean

Among cancers, colorectal cancer is the third most common cancer in the world and the fourth leading cause of cancer deaths worldwide. Some studies have shown that the incidence of colorectal cancer is increasing in Iran and in Fars province. The present study aimed to determine the economic burden of colorectal cancer in patients referred to the referral centers affiliated to Iran, Shiraz University of Medical Sciences in 2019 from the patients’ perspective. This is a partial economic evaluation and a cost-of-illness study conducted cross-sectionally in 2019. All the patients with colorectal cancer who had been referred to the referral centers affiliated to Iran, Shiraz University of Medical Sciences, and had medical records were studied through the census method (N = 96). A researcher-made data collection form was used to collect the cost data. The prevalence-based and bottom-up approaches were also used in this study. The human capital approach was applied to calculate indirect costs. The mean annual cost per patient with colorectal cancer in the present study was $10930.98 purchasing power parity (PPP) (equivalent to 5745.29 USD), the main part of which was the medical direct costs (74.86%). Also, among the medical direct costs per patient, the highest were those of surgeries (41.7%). In addition, the mean annual cost per patient with colorectal cancer in the country was $ 116917762 PPP (equivalent to 61451621.84 USD) in 2019. Regarding the considerable economic burden of colorectal cancer and in order to reduce the costs, these suggestions can be made: increasing the number of specialized beds through the cooperation of health donors, establishing free or low-cost accommodation centers for patients and their companions near the medical centers, using the Internet and cyberspace technologies to follow up the treatment of patients, and increasing insurance coverage and government drug subsidies on drug purchase.

scholarly journals Some kinematics of halo coronal mass ejections

2020 ◽  
Vol 29 (1) ◽  
pp. 81-88
Author(s):  
Virendra Kumar Verma ◽  
Nishant Mittal ◽  
Ramesh Chandra
Keyword(s):  
Coronal Mass Ejections ◽  
Solar Flares ◽  
Coronal Holes ◽  
Geomagnetic Disturbances ◽  
Class A ◽  
Heliospheric Physics ◽  
Class B ◽  
The Mean ◽  
Class C

AbstractWe present an investigation of halo coronal mass ejections (HCMEs) kinematics and other facts about the HCMEs. The study of HCMEs is very important because HCMEs are regarded as the main causes of heliospheric and geomagnetic disturbances. In this study, we have investigated 313 HCMEs observed during 1996-2012 by LASCO, coronal holes, and solar flares. We find that HCMEs are of two types: accelerated HCMEs and decelerated HCMEs. The mean space speed of HCMEs is 1283 km/s while the mean speed of decelerated HCMEs and accelerated HCMEs is 1349 km/s and 1174 km/s, respectively. The investigation shows that 1 (0.3%) HCME was associated with class A SXR, 14 (4.7%) HCMEs were associated with class B SXR-flares, 87 (29.4%) HCMEs were associated with class C SXR-flares, 125 (42.2%) HCMEs were associated with class M SXR-flares and 69 (23.3%) HCMEs were associated with class X SXR-flares. The speed of HCMEs increases with the importance of solar SXR-flares. The various results obtained in the present analysis are discussed in the light of the existing scenario of heliospheric physics.

scholarly journals Genotype-Dependent Tipburn Severity During Lettuce Hydroponic Culture Is Associated with Altered Nutrient Leaf Content

Agronomy ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 616
Author(s):  
Virginia Birlanga ◽  
José Ramón Acosta-Motos ◽  
José Manuel Pérez-Pérez
Keyword(s):  
Low Cost ◽  
Nutrient Content ◽  
Leafy Vegetables ◽  
Production Methods ◽  
Growing Seasons ◽  
Lactuca Sativa L ◽  
Hydroponic Cultivation ◽  
Highly Correlated ◽  
Nutrient Solutions ◽  
Nutrient Traits

Cultivated lettuce (Lactuca sativa L.) is one of the most important leafy vegetables in the world, and most of the production is concentrated in the Mediterranean Basin. Hydroponics has been successfully utilized for lettuce cultivation, which could contribute to the diversification of production methods and the reduction of water consumption and excessive fertilization. We devised a low-cost procedure for closed hydroponic cultivation and easy phenotyping of root and shoot attributes of lettuce. We studied 12 lettuce genotypes of the crisphead and oak-leaf subtypes, which differed on their tipburn resistance, for three growing seasons (Fall, Winter, and Spring). We found interesting genotype × environment (G × E) interactions for some of the studied traits during early growth. By analyzing tipburn incidence and leaf nutrient content, we were able to identify a number of nutrient traits that were highly correlated with cultivar- and genotype-dependent tipburn. Our experimental setup will allow evaluating different lettuce genotypes in defined nutrient solutions to select for tipburn-tolerant and highly productive genotypes that are suitable for hydroponics.

scholarly journals The Difficulty of Predicting Eastern Spruce Dwarf Mistletoe in Lowland Black Spruce: Model Benchmarking in Northern Minnesota, USA

Forests ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 843
Author(s):  
Ella R. Gray ◽  
Matthew B. Russell ◽  
Marcella A. Windmuller-Campione
Keyword(s):  
Stand Structure ◽  
Black Spruce ◽  
Forest Health ◽  
Basal Area ◽  
Predictive Performance ◽  
Stand Age ◽  
Management Decisions ◽  
Dwarf Mistletoe ◽  
Growing Seasons ◽  
Model Interpretation

Insects, fungi, and diseases play an important role in forest stand development and subsequently, forest management decisions and treatments. As these disturbance agents commonly occur within and across landscapes, modeling has often been used to inform forest planning and management decisions. However, models are rarely benchmarked, leaving questions about their utility. Here, we assessed the predictive performance of a Bayesian hierarchical model through on–the-ground sampling to explore what features of stand structure or composition may be important factors related to eastern spruce dwarf mistletoe (Arceuthobium pusillum Peck) presence in lowland black spruce (Picea mariana (Mill.) B. S. P.). Twenty-five state-owned stands included in the predictive model were sampled during the 2019 and 2020 growing seasons. Within each stand, data related to the presence of eastern spruce dwarf mistletoe, stand structure, and species composition were collected. The model accurately predicted eastern spruce dwarf mistletoe occurrence for 13 of the 25 stands. The amount of living and dead black spruce basal area differed significantly based on model prediction and observed infestation, but trees per hectare, total living basal area, diameter at breast height, stand age, and species richness were not significantly different. Our results highlight the benefits of model benchmarking to improve model interpretation as well as to inform our understanding of forest health problems across diverse stand conditions.

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