Tree population changes in treated rain forest at Omo Forest Reserve, south-western Nigeria

1987 ◽  
Vol 3 (4) ◽  
pp. 291-313 ◽  
Author(s):  
D. U. U. Okali ◽  
B. A. Ola-Adams
Keyword(s):  
Rain Forest ◽  
Forest Biomass ◽  
Basal Area ◽  
Walsh System ◽  
Relative Distribution ◽  
Annual Increment ◽  
Forest Reserve ◽  
Number Of Species ◽  
Canopy Opening ◽  
Number Of Stems

ABSTRACTA review of previous evaluations of long-term changes in treated Nigerian rain forest is presented, to show that these studies have concentrated on economic species with little consideration of other species, or of forest biomass and structure.We examine regeneration and successional patterns in Omo Forest Reserve by comparing enumeration data taken before (1952) and after (1981) treatment of the forest by selective canopy opening and climber-cutting (Plot A), or clear-felling and burning (Walsh system) (Plot C).Before treatment, about 50 species in 25 families were found of stems ≥10 cm dbh, in 4.05 ha of the forest, the Euphorbiaceae contributing the greatest number of species while the medium-sized trees Diospyros alboflavescens (Ebenaceae) and Strombosia pustulata (Olacaceae) contributed more than 40% of the stems.Twenty-eight years after treatment (1981) the number of species and families remained similar to those in 1952, although smaller areas (0.75 ha) were enumerated; the treated plots were, however, dominated by early succession species such as Macaranga barteri, Musanga cecropioides, Cleistopholis patens, Funtumia elastica and Fagara macrophylla, and lacked an abundance of the ‘economic’ species that treatment had been expected to induce; the medium-sized trees that were dominant in 1952 were still abundant in Plot A but not in Plot C.For stems ≥ 30 cm dbh tree diversity (reciprocal of Simpson's index) was highest (15.7) in a 1952 plot and least (4.8) in the clear-felled plot enumerated in 1981; diversity of the 1952 plots, however, fell markedly to values lower than those for the 1981 plots when computation was based on all stems ≥10 cm dbh, presumably because of increase in abundance of small-stemmed species like Diospyros spp., Strombosia sp. and Rinorea sp., each represented by a large number of stems.Basal area was greatest (29.6 m2 ha−1) in the 1952 plots and least (12.7 m2 ha−1) in the clear-felled plots enumerated in 1981, but the relative distribution of basal area and number of stems in size-classes was similar in all the plots.Mean annual increment, computed by dividing the mean diameter (7.50 cm) of the stems in the clear-felled plots by the number of years (28) over which they had grown, was 0.27 cm.Nauclea diderrichii dominated the seedling regeneration from the first year after clear-felling and burning (1954) till the sixth year (1960), when seedlings of the Meliaceae entered the regeneration list and overall seedling density was 395 per hectare.Among the plots assessed in 1981, the standing crop was greatest in an untreated Control plot (229.6 t ha−1) followed by Plot A (159.7 t ha−1) and Plot C (91.1 t ha7−1), but the relative allocation of biomass to stem, branch, leaf, root and fruit fractions was comparable for all plots.The data are discussed in relation to other Nigerian forest studies and it is suggested that the main qualitative features of structural organization and the species composition of the top canopy synusia of mature secondary rain forest may be determined quite early in the development of the stand.

scholarly journals Modelling regeneration and recruitment in a tropical rain forest

1992 ◽  
Vol 22 (9) ◽  
pp. 1235-1248 ◽  
Author(s):  
Jerome K. Vanclay
Keyword(s):  
Rain Forest ◽  
Tropical Rain Forest ◽  
Growth Models ◽  
Basal Area ◽  
Relative Number ◽  
Site Quality ◽  
Permanent Sample Plots ◽  
Second Stage ◽  
Number Of Stems ◽  
Stand Basal Area

A two-stage model predicts the recruitment (i.e., the number of stems reaching or exceeding 10 cm DBH) of the 100 species that account for 97% of all the recruitment observed on 217 permanent sample plots in the tropical rain forest of north Queensland. The first stage predicts the probability of the occurrence of any recruitment from stand basal area and the presence of that species in the existing stand. These probabilities can be implemented stochastically, or deterministically by summing the probabilities and initiating recruitment on unity. The second stage indicates the expected amount of recruitment, given that it is known to occur, and employs stand basal area, the relative number of trees of that species in the stand, and site quality. This approach is easily implemented in growth models and planning systems.

scholarly journals Assessment of African Blackwood (Dalbergia melanoxylon) Population Structure in Kilwa District, Tanzania

2021 ◽  
Vol 47 (4) ◽  
pp. 1442-1449
Author(s):  
Agnes M.S. Nyomora ◽  
Washa B. Washa ◽  
Stephen I. Nnungu
Keyword(s):  
Population Structure ◽  
Unit Area ◽  
Calculated Data ◽  
Basal Area ◽  
Population Status ◽  
Forest Reserve ◽  
Community Forests ◽  
Individual Number ◽  
Dalbergia Melanoxylon ◽  
Number Of Stems

Overharvesting and limited conservation efforts have posed a serious threat to future availability of Dalbergia melanoxylon in Tanzania in recent years. The study was conducted between 2018 and 2020 covering Mitarure Forest Reserve (MFR) and 2 surrounding community forests of Ngea and Nambawala in Kilwa District. The purpose of the study was to assess the existing population status of the species in Tanzania. A total of 36 circular plots in Mitarure and 15 plots in each community forest were laid down. Data were recorded for the number of stems per plot, and then converted on per hectare basis where the basal area and densities per hectare were calculated. Data was disaggregated into 5 Diameter at Breast Height (DBH) generated distribution classes ranging from DBH 0 to more than 45 cm. The results revealed that, there was a contrast between the Mitarure Forest Reserve and community forests in terms of individual number of trees per unit area, basal area and densities. The numbers of stems per hectare for the species were found to be 16, 10 and 8 stems/ha in Mitarure, Ngea and Nambawala forest, respectively. Dalbergia melanoxylon in Mitarure forest was normally distributed. The respective basal area was over 80 m2 per ha in Nambawala against over 60 in MFR and Ngea. The results suggest success of the communities in conserving the species after previous overharvest. Authorities should frequently visit forests to increase the population of the species and reduce unauthorised harvesting. Keywords: Dalbegia melanoxylon, Population structure, Mitarure forest reserve, Ngea and Nambawala community forests.

scholarly journals The Fate of a Tropical Rainforest in Nigeria: Abeku Sector of Omo Forest Reserve

2013 ◽  
Vol 6 (2) ◽  
pp. 116-130 ◽  
Keyword(s):  
Basal Area ◽  
Floristic Composition ◽  
Abundant Species ◽  
Diversity Indices ◽  
Forest Monitoring ◽  
Forest Reserve ◽  
Mean Values ◽  
Permanent Sample Plots ◽  
Large Trees ◽  
Number Of Stems

Sixteen permanent sample plots of one hectare each, established in 1985 at Abeku sector of Omo Forest Reserve, South west Nigeria by the European Economic Community/ Nigeria Federal Government (High Forest Monitoring Plots Project) (EEC/HFMPP) were used for this study. The plots were re-enumerated in 1987. Further assessment took place in 1997 and 2000 respectively for the purpose of assessing the floristic characteristics of the plots. The present study aims at assessing the floristic composition during the sampling years. Out of the original 16 plots only eleven and nine plots were available for assessment in 1997 and 2000 respectively. The remaining plots had been converted to plantations of arable and cash crops. The numbers of tree species encountered were 98, 109, 95 and 71 for 1985, 1987, 1997 and 2000 enumerations respectively. Also 28,31, 29 and 23 families were encountered in 1985, 1987, 1997 and 2000 respectively. In terms of density, basal area and spread, the ten most abundant species are Diospyros iturensis (Plant nomenclature follows Hutchinson and Dalziel (1954-72); Keay (1989) and Lowe and Soladoye (1990)), (DIAL),Tabernaemontana pachysiphon (TAPA), Octolobus angustatus (OLAN), Strombosia pustulata (SBPU), Diospyros dendo (DIDE), Diospyros suaveolens (DISU), Drypetes gossweileri (DRGO), Rothmania hispida (ROHI), Hunteria unbellata (HUUM) and Anthonotha aubryanum (ASAU) and the six most prominent families are Ebenaceae, Apocynaceae, Euphorbiaceae, Sterculiaceae, Olacaceae and Rubiaceae .Mean number of stems per hectare ranges from 400.44 to 1134.0 for the small trees (5-20cm dbh); 89.78 to 174.25 for the medium trees (20-40cm dbh) and 8.33 to 17.06 for the large trees (> 40cm dbh) Mean basal area per hectare ranges from 4.94m2 to 8.81m2 for the small trees, 5.4m2 to 9.63m2 for the medium trees and 4.64m2 to 9.04m2 for the large trees. Inverse of Simpson diversity indices range between 15.1 to 16.27 for the small tree, 13.43 to 16.37 for the medium trees and 23.44 to 26.34 for the large trees. The highest mean values per hectare of these parameters were found in 1987 enumeration, while the least values were found in the year 2000 enumeration. This variability may not be due only to the number of plots available for enumeration alone, but also as a result of poaching in the remaining plots before the 2000 enumeration. The study recommends that conscious efforts should be made to protect and maintained the permanent sample plots not only to reduce the possibility of encroachment but also to achieve the objective for which they were established which was to elucidate the dynamics and growth pattern of the natural rainforest. There is also a need for international assistance to achieve this.

Monitoring natural stand change in the forest reserve of Liedekerke, Flanders (Belgium)

1999 ◽  
Vol 64 ◽  
Author(s):  
D. Van den Meersschaut ◽  
B. De Cuyper ◽  
K. Vandekerkhove ◽  
N. Lust
Keyword(s):  
Species Composition ◽  
Castanea Sativa ◽  
Basal Area ◽  
Alnus Glutinosa ◽  
Indigenous Species ◽  
Stem Number ◽  
Mature Trees ◽  
Forest Reserve ◽  
Natural Stand ◽  
Sweet Chestnut

Natural  stand changes in the forest reserve of Liedekerke were analysed during the  period    1986-1996, using a permanent grid of circular plots. The monitoring  concentrated on natural    changes in species composition, using stem number and basal area as  indicators, and changes    in spatial distribution and colonization capacities of trees and shrubs,  with special interest in the    competition between exotic and indigenous species. After only a decade of  monitoring important    natural changes in the woody layer were detected. The pioneer forest is  gradually maturing    through self-thinning processes and shifts in species composition. The  overall stem number    decreased with 33.6%, while the basal area increased with 20.9%. Birch (Betula pendula/    pubescens) and indigenous oak (Quercus robur/petraea) remained  dominant. More tolerant    exotic species, like red oak (Quercus rubra) and sweet chestnut (Castanea  sativa), are slowly    increasing their share in the species composition and expanding their  range. Pioneer species on    the other hand, like aspen (Populus tremula), willow (Salix  capreaicinerealaurita), alder buckthorn    (Frangula alnus) and  common (Alnus glutinosa)  and grey alder (A. incana),  strongly declined.    Black cherry (Prunus serotina) seems to be slowly invading the forest due to its  massive    natural regeneration. Strong competition may be expected especially from  rowan ash (Sorbus    aucuparia), which showed similar regeneration  and colonization capacities. Elder (Sambucus    nigra) dramatically extented its range, though  its share remains marginal. Beech remained absent    most probably due to the lack of mature trees in the vacinity of the  forest. Finally this    change detection allowed that general predictions could be made on the  future natural development    and composition of this forest reserve, which could serve forest management  decisions.

Contribution to the automation of the calculations involving the forest inventory with the aid of an office computer

1970 ◽  
Vol 20 ◽  
Author(s):  
R. Goossens
Keyword(s):  
Tree Species ◽  
Forest Inventory ◽  
Basal Area ◽  
Annual Increment ◽  
Mixed Stands ◽  
Mean Values ◽  
Standing Trees ◽  
General Program ◽  
Magnetic Card ◽  
The Right

Contribution to the automation of the calculations involving  the forest inventory with the aid of an office computer - In this contribution an attempt was made to perform the  calculations involving the forest inventory by means of an office computer  Olivetti P203.     The general program (flowchart 1), identical for all tree species except  for the values of the different parameters, occupies the tracks A and B of a  magnetic card used with this computer. For each tree species one magnetic  card is required, while some supplementary cards are used for the  subroutines. The first subroutine (flowchart 1) enables us to preserve  temporarily the subtotals between two tree species (mixed stands) and so  called special or stand cards (SC). After the last tree species the totals  per ha are calculated and printed on the former, the average trees occuring  on the line below. Appendix 1 gives an example of a similar form resulting  from calculations involving a sampling in a mixed stand consisting of Oak  (code 11), Red oak (code 12), Japanese larch (code 24) and Beech (code 13).  On this form we find from the left to the right: the diameter class (m), the  number of trees per ha, the basal area (m2/ha), the current annual increment  of the basal area (m2/year/ha), current annual volume increment (m3/year/ha),  the volume (m3/ha) and the money value of the standing trees (Bfr/ha). On the  line before the last, the totals of the quantities mentioned above and of all  the tree species together are to be found. The last line gives a survey of  the average values dg, g, ig, ig, v and w.     Besides this form each stand or plot has a so-called 'stand card SC' on  wich the totals cited above as well as the area of the stand or the plot and  its code are stored. Similar 'stand card' may replace in many cases  completely the classical index cards; moreover they have the advantage that  the data can be entered directly into the computer so that further  calculations, classifications or tabling can be carried out by means of an  appropriate program or subroutine. The subroutine 2 (flowchart 2) illustrates  the use of similar cards for a series of stands or eventually a complete  forest, the real values of the different quantities above are calculated and  tabled (taking into account the area). At the same time the general totals  and the general mean values per ha, as well as the average trees are  calculated and printed. Appendix 2 represents a form resulting from such  calculations by means of subroutine 2.

A Growth and Yield Model for Improved Eastern Cottonwood Plantations in the Lower Mississippi Delta

1991 ◽  
Vol 15 (4) ◽  
pp. 213-216 ◽  
Author(s):  
Quang V. Cao ◽  
Kenneth M. Durand
Keyword(s):  
Populus Deltoides ◽  
Mississippi Delta ◽  
Basal Area ◽  
Site Index ◽  
Growth And Yield ◽  
Annual Increment ◽  
Yield Model ◽  
Eastern Cottonwood ◽  
Volume Yield ◽  
Growth And Yield Model

Abstract A compatible growth and yield model was developed based on remeasurement data collected from 183 plots on unthinned improved eastern cottonwood (Populus deltoides Bartr.) plantations in the lower Mississippi Delta. The Sullivan and Clutter (1972) equation form was selected for predicting cubic-foot volume yield and projecting volume from site index and initial age and basal area. Yield equations explained 97% and 94%, respectively, of the variations in total outside bark and merchantable inside bark volumes. Mean annual increment of merchantable volume culminated between 8 and 15 years, depending on site index and initial basal area. South. J. Appl. For. 15(4):213-216.

Pattern in a derived savanna in Nigeria

1991 ◽  
Vol 7 (4) ◽  
pp. 491-502 ◽  
Author(s):  
P. Greig-Smith
Keyword(s):  
Analysis Of Variance ◽  
Block Size ◽  
Basal Area ◽  
Species Density ◽  
Forest Reserve ◽  
South West ◽  
Derived Savanna ◽  
Woody Growth

ABSTRACTAll woody growth was enumerated in three transects, each 960 m x 20 m, in derived savanna in the Olokemeji Forest Reserve in south-west Nigeria. The data for species density, species basal area and stem girth classes were analysed by nested-block analysis of variance and covariance. The use of ‘total covariance’, the sum of all covariances at a block size, contributes to understanding of the pattern present.Three scales of pattern were evident. Patchiness at 160–320 m is interpreted as a response to soil differences or to the pattern of previous farming, which may itself have been determined by soil differences. Patchiness at 20–40 m is attributable to varying intensity of burning. At the smallest scale, of 10 m, there is evidence of regularity of distribution resulting from interference between individuals, possibly due to competition for water.

scholarly journals Changes in the floristic composition of a Terra Firme rain forest In Brazilian Amazonia over an eight-year period In response to logging

2002 ◽  
Vol 32 (2) ◽  
pp. 277-277 ◽  
Author(s):  
João Olegário Pereira de CARVALHO
Keyword(s):  
Rain Forest ◽  
Floristic Composition ◽  
National Forest ◽  
Terra Firme ◽  
Permanent Sample Plots ◽  
Brazilian Amazonia ◽  
Number Of Species

Changes in the floristic composition over an eight-year period in a logged area at the Tapajós National Forest in Brazilian Amazonia arc discussed. Two treatments of different intensities of logging were compared with an undisturbed (control) forest. Data were collected from permanent sample-plots. The effects of logging on floristic composition were stronger in the more heavily logged treatment. The number of species decreased immediately after logging, but started to increase before the fifth year after logging and was higher at the end of the study period than before logging. The more heavily logged plots responded more to disturbances, as judged by the increase in the number of species during the period after logging. This forest appears to recover its initial floristic composition after disturbance without intervention.

scholarly journals TREE DIAMETER GROWTH FOLLOWING SILVICULTURAL TREATMENTS IN A SEMI-DECIDUOUS SECONDARY FOREST IN CENTRAL BRAZIL

CERNE ◽  
2015 ◽  
Vol 21 (1) ◽  
pp. 117-123 ◽  
Author(s):  
Fábio Venturoli ◽  
Augusto César Franco ◽  
Christopher William Fagg
Keyword(s):  
Radial Growth ◽  
Deciduous Forest ◽  
Secondary Forest ◽  
Basal Area ◽  
Diameter Growth ◽  
Annual Increment ◽  
Tree Diameter ◽  
Central Brazil ◽  
Silvicultural Treatments ◽  
Timber Market

In the Cerrado biome of Brazil, savannas and dry forests are intimately linked and form mosaics. These forests are composed of species of high commercial value, well accepted in the timber market, which causes intensive deforestation on the remaining vegetation. Thus, the management of these forests is an important alternative to reduce deforestation in the remaining vegetation. The objective of this study was to analyze the response of tree species in relation to silvicultural treatments of competition and liana cutting in a semi-deciduous forest in Central Brazil. The results showed that community basal area increased 24% over 4.8 years and the median periodic annual increment in diameter was about 20% higher in plots with silvicultural treatments: 2.9 mm.yr-1 in the control compared to 3.2 mm.yr-1 to 3.6 mm.yr-1 between treatments. This study demonstrated that it is possible to increase the rates of radial growth through silvicultural techniques.

Tree density, basal area and species diversity in a disturbed dry tropical forest of northern India: implications for conservation

2006 ◽  
Vol 33 (3) ◽  
pp. 256-262 ◽  
Author(s):  
R. SAGAR ◽  
J.S. SINGH
Keyword(s):  
Species Diversity ◽  
Tropical Forest ◽  
Basal Area ◽  
Tree Density ◽  
Dry Forest ◽  
Conservation Strategies ◽  
Stem Density ◽  
Dry Tropical Forest ◽  
Number Of Species ◽  
Northern India

Dry tropical forest communities are among the world's most threatened systems and urgent measures are required to protect and restore them in degraded landscapes. For planning conservation strategies, there is a need to determine the few essential measurable properties, such as number of species and basal area, that best describe the dry forest vegetation and its environment, and to document quantitative relationships among them. This paper examines the relationships between forest basal area and diversity components (number of species and evenness) for a disturbed dry tropical forest of northern India. Data were collected from five sites located in the Vindhyan dry tropical forest of India, selected on the basis of satellite images and field observations to represent the entire range of conditions in terms of canopy cover and disturbance regimes. These sites represented different communities in terms of species composition. The forest was poorer in species richness, and lower in stem density and basal area than wet forests of the tropics. Across sites (communities), the diversity components and tree density were positively related with total tree basal area. Considering basal area as a surrogate of biomass and net production, diversity is found to be positively associated with productivity. A positive relationship between basal area, tree density and species diversity may be an important characteristic of the dry forest, where recurring disturbance does not permit concentration of biomass or stems in only a few strong competitors. However, the relationships of basal area with density, alpha diversity and evenness remain statistically significant only when data from all sites, including the extremely disturbed one, are used in the analysis. In some sites there was a greater coefficient of variation (CV) of basal area than in others, attributed to patchy distribution of stems and resultant blanks. Therefore, to enhance the tree diversity of these forests, the variability in tree basal area must be reduced by regulating local disturbances. Conservation activities, particularly fuelwood plantations near human settlements, deferred grazing and canopy enrichment through multi-species plantations of nursery-raised or wild-collected seedlings of desirable species within the forest patches of low basal area, will be needed to attain restoration goals, but reforestation programmes will have to be made attractive to the forest-dwelling communities.

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