The mosaic theory of forest regeneration and the determination of forest composition in Ghana

1988 ◽  
Vol 4 (3) ◽  
pp. 253-269 ◽  
Author(s):  
M. D. Swaine ◽  
J. B. Hall
Keyword(s):  
Forest Regeneration ◽  
Abrupt Change ◽  
Recent Literature ◽  
Forest Composition ◽  
Forest Types ◽  
Age Classes ◽  
Forest Zone ◽  
Size Classes ◽  
Forest Sites

ABSTRACTEarly studies comparing adult and juvenile tree populations in West Africa described a contrast in flonstic composition between the two age classes. These studies have been mis-represented in more recent literature, and confusion has arisen over their interpretation.Similar comparisons are reported here for six forest sites in Ghana. At any one site, clear differences in composition were recognized between adult and juvenile samples, but in terms of the variation in flonstic composition over the whole of the forest zone, they are slight and forest types appear to ‘breed true’.At one site, Kade, compositional differences between size classes are fully described for all canopy species on a 0.25 ha plot. There was an abrupt change in composition at about 30 cm gbh. At this site, mortality rates for trees >30 cm gbh were greater amongst species with a high proportion of juveniles in the population. At other sites, changes in composition were sometimes abrupt, occurring at various size classes, or were more gradual.The populations of some species included a large number of juveniles at all sample sites, but the converse, where species always have low densities of juveniles, were not seen. The possible implications of these results for future canopy composition are discussed in relation to temporal equilibrium, or lack of it, in tropical forest composition.

Planting Betula pendula on pine sites infested by Heterobasidion annosum: disease transfer, silvicultural evaluation, and community of wood-inhabiting fungi

2004 ◽  
Vol 34 (1) ◽  
pp. 120-130 ◽  
Author(s):  
Vaidotas Lygis ◽  
Rimvydas Vasiliauskas ◽  
Jan Stenlid
Keyword(s):  
Root Rot ◽  
Forest Regeneration ◽  
Betula Pendula ◽  
Root Systems ◽  
Fungal Species ◽  
Heterobasidion Annosum ◽  
Strong Impact ◽  
Fungal Isolation ◽  
Somatic Incompatibility ◽  
Forest Sites

Persistence of the root rot pathogen Heterobasidion annosum (Fr.) Bref. s.s. on infested areas and its transfer to a forest regeneration was studied in three forest sites in eastern Lithuania. The sites represented H. annosum disease centres in Pinus sylvestris L. stands, which were clear-felled and replanted with Betula pendula Roth 25 years prior to our study. Fungal isolation from trees and stumps on each site was performed on both replanted B. pendula and surrounding P. sylvestris from the previous generation. Low productivity of B. pendula stands (45.0–76.1 m3·ha–1), high mortality rates, and comparatively low vigor of trees (measured as crown densities) indicated a strong impact of root rot. Based on somatic incompatibility tests, we detected large spreading areas of clones of H. annosum (up to 48 m across) and old (35- to 40-year-old) clonal individuals. Territorial clones covered areas that encompassed both previous stands of P. sylvestris and current stands of B. pendula. Our results showed that H. annosum is able to persist in root systems of diseased trees for decades and readily attack birch replanted on infested sites. In addition, a total of 83 fungal species (out of 398 isolates) was found as a result of sampling 508 B. pendula, 49 P. sylvestris, 21 Juniperus communis L., and 1 Salix cinerea L. trees.

scholarly journals Objective determination of the sea age of Atlantic salmon from the sizes and dates of capture of individual fish

2010 ◽  
Vol 68 (1) ◽  
pp. 130-143 ◽  
Author(s):  
Philip J. Bacon ◽  
William S. C. Gurney ◽  
Eddie McKenzie ◽  
Bryce Whyte ◽  
Ronald Campbell ◽  
...  
Keyword(s):  
Atlantic Salmon ◽  
Fishery Management ◽  
East Coast ◽  
Probability Distributions ◽  
Age Classes ◽  
Individual Fish ◽  
Bivariate Probability ◽  
Management And Conservation ◽  
Objective Determination

Abstract Bacon, P. J., Gurney, W. S. C., McKenzie, E., Whyte, B., Campbell, R., Laughton, R., Smith, G., and MacLean, J. 2011. Objective determination of the sea age of Atlantic salmon from the sizes and dates of capture of individual fish. – ICES Journal of Marine Science, 68: 130–143. The sea ages of Atlantic salmon indicate crucial differences between oceanic feeding zones that have important implications for conservation and management. Historical fishery-catch records go back more than 100 years, but the reliability with which they discriminate between sea-age classes is uncertain. Research data from some 188 000 scale-aged Scottish salmon that included size (length, weight) and seasonal date of capture on return to the coast were investigated to devise a means of assigning sea age to individual fish objectively. Two simple bivariate probability distributions are described that discriminate between 1SW and 2SW fish with 97% reliability, and between 2SW and 3SW fish with 70% confidence. The same two probability distributions achieve this accuracy across five major east coast Scottish rivers and five decades. They also achieve the same exactitude for a smaller recent dataset from the Scottish west coast, from the River Tweed a century ago (1894/1895), and for salmon caught by rod near the estuary. More surprisingly, they also achieve the same success for rod-caught salmon taken at beats remote from the estuary and including capture dates when some fish could have been in the river for a few months. The implications of these findings for fishery management and conservation are discussed.

scholarly journals Estimating Carbon Sequestration Rates and Total Carbon Stockpile in Degraded and Non-Degraded Sites of Oak and Pine Forest of Kumaun Central Himalaya

2009 ◽  
Vol 15 ◽  
pp. 75-81 ◽  
Author(s):  
B. S. Jina ◽  
Pankaj Sah ◽  
M. D. Bhatt ◽  
Y. S. Rawat
Keyword(s):  
Global Warming ◽  
Carbon Sequestration ◽  
Total Carbon ◽  
Oak Forests ◽  
Carbon Trading ◽  
Central Himalaya ◽  
Forest Types ◽  
Community Forests ◽  
The People ◽  
Forest Sites

We calculated the rates at which CO2 is being sequestered in two different forest types of Himalaya. For our comparative study we took the degraded and non-degraded sites of pine and oak forests in Kumaun Central Himalaya. The Van Panchayats (VPs) or Community Forests are managing the nondegraded forest sites for centuries, and from this research we have come to know that the sequestration of CO2 in these non-degraded forests is significantly greater than the degraded forests. The paper recommends the significance of community forests in both Uttarakhand and the world, and advocates that if we want to fight against global warming, we must encourage the community forests and that the people living in severe poverty in these forest areas who become the unsung heroes in the war against global warming, must be paid in lieu of saving their forests, which ultimately become the sink for increased CO2 worldwide. This business or ‘carbon trading' will indeed evolve as the panacea against the war against global warming. Key words: Carbon sequestration, community forests, Van Panchayats, green house gases, global warming, carbon trading.   doi: 10.3126/eco.v15i0.1946 ECOPRINT 15: 75-81, 2008

scholarly journals Morphological variation of Cedrela odorata (Meliaceae): contrast between natural and managed populations

2018 ◽  
pp. 157-171 ◽  
Author(s):  
Dulce María Galván-Hernández ◽  
Manuel Alejandro Macedo-Villareal ◽  
Francisco Federico Núñez de Cáceres-González ◽  
Arturo Sánchez-González ◽  
Pablo Octavio-Aguilar
Keyword(s):  
Morphological Variation ◽  
Natural Populations ◽  
Forest Composition ◽  
Cedrela Odorata ◽  
Size Classes ◽  
Factors Analysis ◽  
Height Class ◽  
Lower Height ◽  
Specific Association ◽  
Spanish Cedar

Background and Aims: Cedrela odorata (Spanish cedar) is a tropical tree native to America with an important international trade market. In this study, the morphological variation of C. odorata was compared among three conditions: logging, plantations, and natural populations, with the objective to evaluate the current condition of managed populations after harvesting and in plantations, in contrast to relatively well-preserved populations.Methods: Two sites were chosen for each condition. The population density and four morphological attributes were measured: diameter at breast height, height, angle of branch insertion and crown form. A multivariate approach was used to compare the morphological variation among conditions (generalized discriminant factors analysis) and determine total variation distributed among size classes (cluster analysis), as well as assignment of these classes to each condition (canonical correspondence analysis).Key results: Four significantly different size classes were identified among all populations with specific association to condition. Strongest correlations were between highest trees with natural populations and small trees with plantations. Forest management, including harvesting and plantation conditions, reduced the phenotypical variation and modified the dasometrical attributes of C. odorata. The logging of the better shaped phenotypes increased the smaller size trees frequency compared to commercial size individuals, and changed the forest composition favoring small categories.Conclusions: The forest exploitation generates homogenization in median height-class and the plantation in lower height-class. In both cases, the harvestable trees are scarce, even after 20 years of management; and they are non-existent in plantations of 15 years. These results suggest that the removal of the highest trees, as well as forest plantations, are not being effective to wood production since they do not reach commercial sizes in the time of recovery or projected growth. 

scholarly journals Why direct and post-refinement determinations of absolute structure may give different results

2016 ◽  
Vol 72 (5) ◽  
pp. 661-683 ◽  
Author(s):  
David John Watkin ◽  
Richard Ian Cooper
Keyword(s):  
Recent Literature ◽  
Structure Refinement ◽  
Direct Determination ◽  
Standard Uncertainty ◽  
Data Sets ◽  
Normal Probability Plot ◽  
Normal Probability ◽  
Structure Determinations ◽  
Absolute Structure

Direct determination of the Flack parameter as part of the structure refinement procedure usually gives different, though similar, values to post-refinement methods. The source of this discrepancy has been probed by analysing a range of data sets taken from the recent literature. Most significantly, it was observed that the directly refined Flack (x) parameter and its standard uncertainty are usually not much influenced by changes in the refinement weighting schemes, but if they are then there are probably problems with the data or model. Post-refinement analyses give Flack parameters strongly influenced by the choice of weights. Weights derived from those used in the main least squares lead to post-refinement estimates of the Flack parameters and their standard uncertainties very similar to those obtained by direct refinement. Weights derived from the variances of the observed structure amplitudes are more appropriate and often yield post-refinement Flack parameters similar to those from direct refinement, but always with lower standard uncertainties. Substantial disagreement between direct and post-refinement determinations are strongly indicative of problems with the data, which may be difficult to identify. Examples drawn from 28 structure determinations are provided showing a range of different underlying problems. It seems likely that post-refinement methods taking into account the slope of the normal probability plot are currently the most robust estimators of absolute structure and should be reported along with the directly refined values.

scholarly journals Variation of conducting area in stems of European larch (Larix deciduas) growing in fresh mixed coniferous forest and fresh mixed forest sites

2010 ◽  
Vol 56 (No. 1) ◽  
pp. 18-27 ◽  
Author(s):  
M. Nawrot ◽  
M. Jakubowski ◽  
W. Pazdrowski ◽  
K. Kaźmierczak ◽  
M. Szymański
Keyword(s):  
Coniferous Forest ◽  
Mixed Forest ◽  
Coefficient Of Determination ◽  
Forest Site ◽  
Age Classes ◽  
Main Crop ◽  
Forest Sites ◽  
The Social ◽  
Individual Trees ◽  
Site Types

The paper presents an attempt to determine conducting area (CA), relative conducting area (CA.k<sup>–1</sup>) and mean ring conducting area (CAar) on discs cut at breast height from stems of larch trees growing in fresh mixed coniferous forest and fresh mixed forest sites, representing four age classes and the main crop according to Kraft’s classification. The value of CA increases with an improvement of the social class of tree position in the community, while no such dependences were found for the value of (CA.k<sup>–1</sup>). The parameter CAar, except for one case in age class IV in the fresh mixed coniferous forest site, increases with an improvement of the position a tree takes in the community and differentiates more markedly under the conditions of fresh mixed forest sites. Relative conducting area (CA.k<sup>–1</sup>) decreases markedly with an increase in the age of trees, which is confirmed by high values of the coefficient of determination. Moreover, the significance of differences between individual trees in the main crop according to Kraft and forest site types was tested in terms of the values of CAar. Calculated values may be used to describe the relationships between conducting area and the size of the assimilating organ more precisely than the total sapwood zone.

Monthly Litterfall Dynamics in Three Different Forest Types in Jeju Island, South Korea

2018 ◽  
Author(s):  
Ji Young An ◽  
Si Ho Han ◽  
Woo Bin Youn ◽  
Sang Ick Lee ◽  
Afroja Rahman ◽  
...  
Keyword(s):  
Nutrient Cycling ◽  
Leaf Litter ◽  
Dominant Species ◽  
Forest Type ◽  
Jeju Island ◽  
Forest Composition ◽  
Forest Types ◽  
Major Pathway ◽  
Litterfall Production ◽  
High Precipitation

In a forest ecosystem, the major pathway for carbon and nutrient cycling is through litterfall, which has been influenced by physical and biological factors. The purpose of this study was to investigate monthly litterfall production in three forests in Jeju Island differentiated based on precipitation and forest composition: Chungsu (&lt;i&gt;Quercus glauca&lt;/i&gt; as the dominant species; low precipitation), Seonheul&lt;sub&gt;b&lt;/sub&gt; (&lt;i&gt;Q. glauca&lt;/i&gt; as the dominant species; high precipitation), and Seonheul&lt;sub&gt;m&lt;/sub&gt; (&lt;i&gt;Q. glauca&lt;/i&gt; and &lt;i&gt;Pinus thunbergii&lt;/i&gt; as the dominant species; high precipitation). Litterfall was collected monthly from April to December 2015 and divided into leaf litter, twig, bark, seeds, and unidentified materials. The amount of leaf litter by species varied by stand, but leaf litter and total litterfall were very similar among stands, ranging from 362 g m&lt;sup&gt;-2&lt;/sup&gt; to 375 g m&lt;sup&gt;-2&lt;/sup&gt; for leaf litter and 524 g m&lt;sup&gt;-2&lt;/sup&gt; to 580 g m&lt;sup&gt;-2&lt;/sup&gt; for total litterfall. However, oak leaf litter was the highest in May, but needle litter was the highest in December. Forest type and climate factor had no influence on the amount of litterfall in the studied forests while the litterfall production by species showed considerable seasonal variation, resulting in varying effects on carbon and nutrient cycling in these forests.

scholarly journals Formation of high-power, high-voltage rectangular pulses with the controlled stabilization of the pulse peak

2017 ◽  
Vol 35 (1) ◽  
pp. 154-158
Author(s):  
A.V. Petrov ◽  
S.K. Pavlov ◽  
Y.P. Usov
Keyword(s):  
Abrupt Change ◽  
Electrical Circuit ◽  
Storage Device ◽  
Resistive Load ◽  
Pulse Shaper ◽  
Short Term ◽  
Pulse Peak ◽  
Active Switch ◽  
Analytical Expressions

AbstractThe pulse shaper based on a capacitive storage device with an active switch operating on a resistive load is considered. The electrical circuit includes a capacitor with a reference voltage for the stabilization of peak of the pulse. The capacitor connected in parallel with a load via the unilateral conductive switch. A general analysis of the shaping circuit was carried out. Analytical expressions for determination of the stabilization accuracy and the stabilization duration have been obtained. The results of computer simulation of dependence of these characteristics as function of pulse parameters and shaper features are presented. The influence of short-term and abrupt change of the resistance load on the stabilization process of peak of the pulse is considered. The possibility of obtaining of pulses with a controlled stability of pulse peaks <1% for pulses with duration to 100 µs at voltages up to 20 kV and energy stored in a capacitor to 3.4 kJ is shown in prototype of the shaper.

scholarly journals Generic Composition, Structure and Diversity of Secondary Forests at Amisconde, the Pacific Slope of the Cordillera de Talamanca, Costa Rica

2015 ◽  
pp. 1069-1079
Author(s):  
D A P Hooftman
Keyword(s):  
Elevation Gradient ◽  
Forest Composition ◽  
Primary Forest ◽  
Forest Belt ◽  
Forest Age ◽  
Forest Types ◽  
Elevation Gradients ◽  
Positive Correlation ◽  
Composition Structure ◽  
Cordillera De Talamanca

Most Costa Rican forests have been intensively studied in recent years. One exception is the transition zone from lowland wet forest to the high elevatíon Quercus forest belt al Ihe pacific slopes of the Cordillera de Talamanca. An inventory of secondary forest composition, structure and diversity was done on a specific slope (l150- 2300-m elevation) in the conservation and development project Amisconde. Thirteen plots of 500 m2 were evenly spread a10ng an elevation gradient. Specimens were collected of a11 woody individuals (> 3 cm DBH), dried, placed in a herbarium of morphospecies and afterwards identified. In total 90 genera within 49 families were found. The vegetation was separated in three forest types using TWINSPAN c1assification. Forest types were elevatíon based. Elevation and forest age showed (overall) no correlatíon with diversity using ANOVA, with the single exceptíon of a positíve correlatíon of the number of genera and elevatíon. This was opposite to the negative correlations mostly found on elevatíon gradients. The main factors for this positíve correlation were the level of recent disturbance and the distance to primary forest, in combination wíth forest age

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