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.

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.

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.

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 Seasonal and needle age-related variations in the biochemical characteristics of Pinus nigra subsp. pallasiana (Lamb.) Holmboe

2018 ◽  
Vol 64 (No. 9) ◽  
pp. 379-386 ◽  
Author(s):  
Deligöz Ayşe ◽  
Bayar Esra ◽  
Genç Musa ◽  
Karatepe Yasin ◽  
Kirdar Erol ◽  
...  
Keyword(s):  
Pinus Nigra ◽  
Carbohydrate Content ◽  
Seasonal Patterns ◽  
Age Classes ◽  
Total Carbohydrate ◽  
Needle Age ◽  
Total Carbohydrate Content ◽  
Age Related ◽  
Pigment Contents ◽  
Carbohydrate Contents

Variations in the photosynthetic pigments and total carbohydrate contents of needles of different age classes (current-year, 1-year-old, 2-year-old and 3-year-old) of Pinus nigra subsp. pallasiana (Lambert) Holmboe trees in a young natural stand were investigated during the growing season. In current-year needles, total carbohydrate content was lower during June and July when the needle growth continued than in older age classes, but it was similar to other age classes in the months of August to October. Seasonal patterns of variations in total carbohydrate content were almost similar in 1-, 2-, and 3-year-old needles. Chlorophyll and carotenoid contents increased from May to June, remained relatively constant or declined slightly during summer and autumn in 1-, 2-, and 3-year-old needles. In October, the pigment content was highest in 1-year-old needles, and lowest in 3-year-old needles. Our study indicated that total carbohydrate and pigment contents were affected by needle age classes and seasons.

Timber production versus old-growth preservation with endogenous prices and forest age-classes

2004 ◽  
Vol 34 (6) ◽  
pp. 1296-1310 ◽  
Author(s):  
Olli Tahvonen
Keyword(s):  
Environmental Values ◽  
Timber Harvesting ◽  
Timber Production ◽  
Forest Age ◽  
Forest Land ◽  
Age Classes ◽  
Old Growth ◽  
Class Distribution ◽  
Age Class ◽  
Long Run

This study combines timber production and environmental values, applying a dynamic forest-level economic model with any number of forest age-classes. The model includes endogenous timber price or nonlinear harvesting costs and various possibilities to specify the dependence of environmental values (related e.g. to species persistence) on the forest age-class structure. The nonlinearities in the net benefits from timber production have the consequence that fluctuations in optimal timber harvesting may totally vanish or at least become smaller than in forest scheduling models without ad hoc even flow constraints. If environmental values are specified to depend on the fraction of forest land preserved as old growth, the optimal long run allocation between timber production and old growth is represented by an equilibrium continuum. Thus the optimal long run allocation depends on the initial age-class distribution. The continuum and the dependence of initial age-class distribution vanish when the rate of discount approaches zero. If the environmental values of age-classes increase smoothly with age, the long run equilibrium may simultaneously include multiple rotation periods. The model determines the optimality of producing timber and environmental values separately at different parts of the forest or at the same piece of forest land. Numerical computation suggests that the optimal solution always converges toward some optimal long run stationary age-class distribution.

scholarly journals FURTHER INVESTIGATIONS ON THE ORIGIN OF TUMORS IN MICE

1915 ◽  
Vol 22 (6) ◽  
pp. 713-731 ◽  
Author(s):  
A. E. C. Lathrop ◽  
Leo Loeb
Keyword(s):  
Tumor Incidence ◽  
Age Classes ◽  
Age Class ◽  
The Difference ◽  
Different Strains

1. In crossing strains known to diner in their tumor rates, the hybrids show in a considerable number of cases a tumor rate corresponding to the parent with a high tumor incidence; in some cases the offspring have the tumor rate of the parent with the low tumor incidence; in certain cases the tumor rate of the offspring is intermediate between those of the parents. That these results are not accidental follows from the fact that we could show in some cases that two sisters crossed with the same strains or with the same male give similar offspring, and in other cases we could show that the same individual crossed successively with two strains that behave similarly produces hybrids with a similar tumor incidence. 2. There exists some evidence for the conclusion that different strains in being crossed with other strains differ in their power to impress their tumor rate upon the crosses. Thus the English strain and the I and II daughters of No. 10 have the tendency to transmit to the offspring a high tumor rate, while Cream, Silver, and some European other than 151 have a tendency to transmit a low tumor rate. While crosses of these daughters of No. 10 with European 151 or with No. 8½ show the high tumor rate of the mothers, the crosses of one of the same females with Cream or Silver show an intermediate tumor rate. 3. We find further evidence for our conclusion previously stated that age class, of the tumors and tumor rate are not dependent on the same factor. The age class enters into the crosses as a factor independent of the tumor rate. Thus we find in the crosses between the first daughter of No. 10 and Cream, and in the crosses between the same female and English Silver a similar tumor rate, but the age classes differ in conformity with the difference in the age classes of the parents. We find, furthermore, that while in some cases a tumor rate and an age class that correspond to each other (high tumor rate, early tumors—low tumor rate, late tumors) are transmitted to the offspring, in other cases tumor rate and age class transmitted to the crosses diverge. 4. It seems that certain strains with very late tumors if mated with strains with earlier tumors have a tendency to transmit to the offspring their own tendency to very late tumors. With a certain strain lateness of the tumors seems to be dominant, while a low tumor rate is not necessarily dominant in the same crosses. This was noticeable in the crosses into which the strain European ± 102 or 103 entered as one of the parents. 5. If both parents have a similar tumor rate the offspring have usually a similar tumor rate. There was, however, one exception to this rule in the case of the German ± Carter mice, in which the offspring showed a much lower tumor rate and higher age class than either of the parent strains.

scholarly journals A PRACTICAL MEASURE OF STOCK DENSITY IN WHITE AND RED PINE STANDS

1943 ◽  
Vol 19 (2) ◽  
pp. 108-118 ◽  
Author(s):  
G. A. Mulloy
Keyword(s):  
Line Graph ◽  
Stand Density ◽  
Average Diameter ◽  
Practical Application ◽  
White Pine ◽  
Age Classes ◽  
Straight Line ◽  
Pine Stands ◽  
Stand Density Index ◽  
Practical Measure

The findings of L. H. Reineke that a number of trees per acre on average diameter plotted on double logarithmic paper provides a straight line graph whose slope remains constant for all sites, age-classes and most species are checked against twenty years' record of sample plot data for red and white pine stands. The use of stand density index based on this principle in thinning technique and in forest management is developed.The practical application of these findings is shown. All that is necessary is to estimate the average diameter of the stand. The spacing for optimum development is then fixed.

scholarly journals Effect of Day or Night and Cumulative Shift Time on the Frequency of Tree Damage during CTL Harvesting in Various Stand Conditions

Forests ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 743 ◽  
Author(s):  
Mariusz Bembenek ◽  
Petros A. Tsioras ◽  
Zbigniew Karaszewski ◽  
Bogna Zawieja ◽  
Ewa Bakinowska ◽  
...  
Keyword(s):  
Forest Management ◽  
Human Factor ◽  
Stand Density ◽  
Age Classes ◽  
Tree Damage ◽  
Thinning Intensity ◽  
Thinning Operations ◽  
Work Shifts ◽  
Pine Stands ◽  
Stand Conditions

Thinning is one of the most important tools of forest management, although thinning operations require the use of machines which ultimately cause damage to the remaining stand. The level of damage largely depends on the human factor, and a tired, less focused operator will create more injuries in the forest. With this in mind, the objectives of this research were to find out whether the probability of tree damage caused by an operator is also affected by: (1) the part of the day (dawn/day/dusk/night), and (2) the cumulative shift time. The research was carried out in pure pine stands of different ages, density and thinning intensities. Sample plots were selected that had an increasing number of trees per hectare and growing thinning intensities were applied. The same Komatsu 931.1 harvester was used for the thinning operations in each stand. In all the age classes combined, 5.41% of the remaining trees were wounded. There was a significant influence of the part of the day on the percentage of damaged trees, which was positively correlated with the cumulative shift time. Stand conditions, such as age class and stand density, as well as thinning characteristics—thinning intensity, number of harvested trees and productivity—have different effects on the distribution of damage intensity and on probability. The results may improve the planning of operators’ work shifts in forests of various ages and densities, allowing harvester productivity to be maintained while at the same time inflicting the lowest possible level of damage.

Methimazole Treatment and Risk of Acute Pancreatitis: A Population-based Cohort Study

2020 ◽  
Vol 105 (12) ◽  
pp. e4527-e4530
Author(s):  
Alessandro Pecere ◽  
Marina Caputo ◽  
Andrea Sarro ◽  
Andrealuna Ucciero ◽  
Angelica Zibetti ◽  
...  
Keyword(s):  
Acute Pancreatitis ◽  
Absolute Risk ◽  
Population Based ◽  
Age Classes ◽  
Population Based Study ◽  
Increased Risk ◽  
Hospital Discharge Records ◽  
Adjusted Rate ◽  
Administrative Health Databases ◽  
Rate Ratios

Abstract Context A warning has been recently issued by the European Medicine Agency (EMA) regarding a potential increased risk of acute pancreatitis (AP) in methimazole (MMI) users. Objective To investigate the association between MMI and the diagnosis of AP in a population-based study. Materials and Methods A retrospective analysis of administrative health databases was conducted (2013–2018). Relevant data were obtained from: (1) inhabitants registry, (2) hospital discharge records (ICD-9-CM 577.0), and (3) drug claims registry (ATC H03BB02). We evaluated AP risk in MMI users in 18 months of treatment, stratifying results by trimester. Poisson regression was used to estimate the age- and sex-adjusted rate ratios (RR), and the relative 95% confidence intervals (CI), comparing rates of AP between MMI users and nonusers. The absolute risk of AP in MMI users was also calculated. Results A total of 23 087 new users of MMI were identified. Among them, 61 hospitalizations occurred during the study period. An increase in AP risk was evident during the first 3 trimesters of therapy (RR 3.40 [95% CI: 2.12–5.48]; RR 2.40 [95% CI: 1.36–4.23]; RR 2.80 [95% CI: 1.66–4.73]), but disappeared thereafter. The AP absolute risk in MMI users during the first 18 months of treatment was less than 0.4% in all sex and age classes. Conclusions Our results support the EMA warning, suggesting an increased risk of AP associated with MMI use. However, such an increase seems limited to the first months of MMI treatment. Moreover, in absolute terms, the probability of AP is low among patients, well below 1%.

Testing the accuracy of using peroxidase activity to indicate stigma receptivity

1987 ◽  
Vol 65 (1) ◽  
pp. 107-111 ◽  
Author(s):  
Candace Galen ◽  
R. C. Plowright
Keyword(s):  
Peroxidase Activity ◽  
Pollen Germination ◽  
Age Classes ◽  
Stigma Receptivity ◽  
Age Class ◽  
Stigma Surface ◽  
Hand Pollination ◽  
Flower Age ◽  
Adhesion Rate ◽  
Pedicularis Canadensis

Stigma peroxidase activity was tested in flowers of Pedicularis canadensis and Clintonia borealis at discrete age-classes during the course of anthesis. For recipient flowers of each age-class pollen adhesion, rate of pollen germination, and total number of grains germinating on stigmas were scored following hand-pollination. In P. canadensis, the onset of detectable peroxidase activity occurred at the transition from the juvenile to pollen-dehiscing age-class. Concurrently, the stickiness of the stigma surface and total number of grains germinating on the stigma increased significantly. Stigma peroxidase was present to some degree throughout anthesis in C. borealis. However, the percentage of the stigma surface in which peroxidase was detectable increased significantly between straight-sided and medium-curled flower age-classes. Again, corresponding increases occurred in the stickiness of the stigma surface and total number of grains germinating. Results suggest that for both species stigma peroxidase activity is a reliable indicator of receptivity.

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