The timing and nature of floristic and structural changes during secondary succession in wet forests

2008 ◽  
Vol 56 (3) ◽  
pp. 220 ◽  
Author(s):  
Merrilyn Serong ◽  
Alan Lill
Keyword(s):  
Secondary Succession ◽  
Structural Changes ◽  
Timber Harvesting ◽  
Stem Density ◽  
Forest Age ◽  
Age Classes ◽  
Age Class ◽  
Mountain Ash ◽  
Wet Forests ◽  
Severe Disturbance

The timing and nature of floristic and structural changes to vegetation were documented during secondary succession in wet forests in the Victorian Central Highlands from 3 to > 100 years after severe disturbance by timber-harvesting or wildfire. A chronosequence of five forest age-classes was employed. Vegetation surveys were conducted in two 15 × 50 m sampling quadrats in each of 12 replicate sites in each forest age-class between April 2000 and June 2001. Frequencies of occurrence of 67 floristic variables (plant taxa, other vegetation elements and litter components) were used to distinguish among plant communities in the different forest age-classes. Structural comparisons were made among the age-classes using species richness, floristic variability (i.e. spatial heterogeneity), trunk diameter and stem density of Mountain Ash Eucalyptus regnans F.Muell. and heights of forest strata. Most patterns of change showed a clear unidirectional trend from the youngest to the oldest age-class. Much of the floristic change occurred within a few decades of disturbance, but some of the structural changes continued throughout succession. Vegetation changes were generally attributable to natural succession, but a few differences between young forests that regenerated after timber-harvesting and older forests that originated after wildfire were likely to be due to the different disturbance histories. The pattern of vegetation change during secondary succession in forests after severe disturbance can influence the pattern of forest use by birds. The findings of this study thus formed the foundation of an examination of the community and behavioural responses of diurnal birds to secondary succession.

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.

Plasticity and Stereotypy in Avian Foraging during Secondary Succession in Temperate Forests

2016 ◽  
Vol 9 (3) ◽  
pp. 174-194 ◽  
Author(s):  
Merrilyn Serong ◽  
Alan Lill
Keyword(s):  
Anthropogenic Disturbance ◽  
Secondary Succession ◽  
Foraging Behaviour ◽  
Bird Species ◽  
Timber Harvesting ◽  
Eucalyptus Regnans ◽  
Mountain Ash ◽  
Bird Species Diversity ◽  
Resident Bird ◽  
Chronosequence Approach

Some bird species cannot persist during early secondary succession after natural or anthropogenic disturbance of Australian Mountain Ash ( Eucalyptus regnans) forest, whilst others remain abundant throughout regeneration. To conserve bird species diversity optimally in such forests, we need to know, inter alia, exactly why the latter species can persist after disturbance. Using a chronosequence approach, we documented four facets of foraging in a suite of these persistent species effectively covering 100 years of succession in E. regnans forest disturbed by wildfire or timber harvesting, namely the foraging strata, locations, substrates and behaviours used. Most species showed plasticity in their use of foraging strata and locations during succession, but four exhibited some limited stereotypy in these facets. In contrast, use of foraging substrates and behaviours was largely invariant within species during secondary succession. We suggest that switching foraging strata and locations was probably critical to persistence of most of these bird species during secondary succession, given the marked variation in structural and floristic variables that characterises this regeneration process. Some plasticity in foraging behaviour repertoire and substrate use was probably possible, but not beneficial. Although some resident bird species’ populations were severely reduced by disturbance in these forests, a substantial subset of species was sufficiently flexible in choosing foraging microhabitats to persist throughout secondary succession at pre-disturbance abundances.

scholarly journals Stand damage when harvesting timber using a tractor for extraction

2013 ◽  
Vol 74 (1) ◽  
pp. 27-33 ◽  
Author(s):  
Zbigniew Karaszewski ◽  
Dieter F. Giefing ◽  
Piotr S. Mederski ◽  
Mariusz Bembenek ◽  
Anita Dobek ◽  
...  
Keyword(s):  
Statistical Difference ◽  
Timber Harvesting ◽  
Age Classes ◽  
Substantial Impact ◽  
Age Class ◽  
Thinning Operations ◽  
Stand Damage ◽  
Agricultural Tractor ◽  
Timber Extraction

Abstract Damage to the remaining stand is an unavoidable consequence of thinning operations. The different machines used for timber extraction differ in the level of damage of trees they cause, mainly through wounds to the bark and cambium which can make a substantial impact on the remaining trees. Three different methods of timber harvesting with a chainsaw were analyzed: the short wood system (SWS), the long wood system (LWS) and the full tree system (FTS) in which an agricultural tractor is used for timber extracting. All systems were analyzed in stands containing three different age classes: 2nd (21-40 years), 3rd (41-60 years) and 4th (61-80 years). The level of damage to the remaining stand was assessed considering the percentage of trees exhibiting wounds (scratched bark and/or damage to the cambium) to calculate an index of stand damage (WDI) which incorporated the volume of harvested timber per hectare. The SWS produced the lowest damage to trees in stands of all age classes: average 5%, with the less damage in the oldest stand. After using the LWS, 9% of trees were wounded; in this method there was no statistical difference in frequency of wounding across all the analyzed stands. The highest level of damage was incurred after the FTS, causing 11% of trees to be injured. In stands of the 2nd age class, the method of timber harvesting had no statistically significant effect on the amount of wounding endured. The WDI was lowest in SWS: 0.08, higher in LWS: 0.15 and the highest, 0.23, when FTS was applied.

The influence of time since fire and distance from fire boundary on the distribution and abundance of arboreal marsupials in Eucalyptus regnans-dominated forest in the Central Highlands of Victoria

2002 ◽  
Vol 29 (2) ◽  
pp. 151 ◽  
Author(s):  
R. van der Ree ◽  
R. H. Loyn
Keyword(s):  
Brushtail Possum ◽  
Age Classes ◽  
Eucalyptus Regnans ◽  
Salvage Logging ◽  
Age Class ◽  
Time Since Fire ◽  
Arboreal Marsupials ◽  
Mountain Ash ◽  
Central Highlands ◽  
The Impact

The impact of time since fire after two consecutive wildfires 44 years apart (1939 and 1983) within the same area, and the distance from the fire boundary (<100 m or 500-2000 m), were investigated in relation to the distribution and abundance of arboreal marsupials in 1994. Arboreal marsupials were censused by stagwatching and spotlighting in two relatively young age classes of mountain ash (Eucalyptus regnans) dominated forest in the Central Highlands of Victoria. Five species of arboreal marsupial were detected, but only three were detected in sufficient numbers to determine habitat preferences. Petauroides volans (greater glider) was statistically more abundant in 1939 regrowth forests, while Trichosurus caninus (mountain brushtail possum) showed no significant preference for either age class of forest. All but one record of Gymnobelideus leadbeateri (Leadbeater's possum) came from young forest, though the effect of age-class was not statistically significant. Distance from fire boundary explained little or no variation in mammal distribution or abundance. While the actual number of hollow-bearing trees was similar in both age classes of forest, the long-term lifespan of hollow-bearing trees in more recently burnt forest is predicted to be lower than in unburnt or not recently burnt forest. Post-fire salvage logging following the 1983 wildfires appears to have reduced the number of hollow-bearing trees at sites burnt in 1983.

The Missing Tail and Other Considerations for the Use of Fire History Models

1995 ◽  
Vol 5 (4) ◽  
pp. 197 ◽  
Author(s):  
MA Finney
Keyword(s):  
Exponential Distribution ◽  
Exponential Model ◽  
Forest Age ◽  
Age Classes ◽  
Class Distribution ◽  
Age Class ◽  
Negative Exponential Distribution ◽  
Negative Exponential Model ◽  
Negative Exponential ◽  
Tests Of Fit

This paper reviews methods used for testing the fit of the cumulative form of a negative exponential distribution to the cumulative distribution of forest age-classes. It is shown that existing methods can lead to a greater chance of falsely rejecting the fit of the negative exponential model and inferring that fire frequencies have changed through time. This results when the old-age tail of a negative exponential distribution is mathematically assumed to be present at the end of the age-class distribution. In reality, the tail is censored from sample distributions of forest age-classes. Censoring alters the shape of a cumulative age-class distribution from the straight line expected for a semi-log graph of the cumulative negative exponential model. A solution to this problem is proposed that restricts the tests-of-fit to the portion of the negative exponential distribution that overlaps with the data to be tested. The cumulative age-class distribution can then be compared directly with the cumulative of a truncated negative exponential distribution. Considerations for interpreting a poor fit are then discussed.

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.

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.

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.

The Use of Graphical Methods to Estimate Demographic Parameters

1989 ◽  
Vol 69 (2) ◽  
pp. 367-371 ◽  
Author(s):  
Alastair Grant
Keyword(s):  
Undergraduate Students ◽  
Size Structure ◽  
Size Variation ◽  
Demographic Parameters ◽  
Graphical Methods ◽  
Age Classes ◽  
Size Frequency Distribution ◽  
Age Class ◽  
Frequency Histogram ◽  
Size Frequency

The demographic parameters of a population (the number of age-classes present; growth rates; mortality as a function of age and recruitment levels) are of considerable interest to marine biologists. If individuals can be aged from growth rings in their hard parts, then the estimation of demographic parameters is relatively straightforward. If this is not possible, the next best alternative is to tag or mark individuals and use data on the recapture of these to give the information required. For many marine invertebrates, neither of these options is practical and we must resort to estimating the demographic parameters by making assumptions about recruitment and the size variation between individuals of the same age and then infer the age structure of the population from its size structure. This was first done by Petersen (1891) who interpreted each mode on a size/ frequency histogram as representing a single age-class. More recently, extensive use has been made of methods which assume that the sizes of individuals of the same age will be normally distributed. The size/frequency histogram can then be decomposed into a number of normal distributions, each of which represents a single age-class. This can be done graphically (Harding, 1949; Cassie, 1954; Bhattacharya, 1967) or with computerbased numerical methods (Macdonald & Pitcher, 1979). The graphical methods seem to be the most popular and are frequently taught to undergraduate students. The same methods can be used to dissect a size/frequency distribution into components other than age-classes (Harding, 1949), but the principles are the same.

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