scholarly journals Caractérisation structurale des peuplements naturels de Khaya anthotheca (Welw.) C.DC dans les concessions forestières du Sud-Ouest de la République Centrafricaine

2020 ◽  
Vol 14 (7) ◽  
pp. 2491-2505
Author(s):  
Bruce Deguene ◽  
Gorgon Igor Touckia ◽  
Olga Diane Yongo ◽  
Jean Joël Loumeto
Keyword(s):  
Coefficient Of Variation ◽  
Sustainable Management ◽  
Scientific Information ◽  
Natural Populations ◽  
Basal Area ◽  
Average Density ◽  
République Centrafricaine ◽  
Structural Characterisation ◽  
South West ◽  
Forest Concessions

L’objectif de cette étude est d’apporter des informations scientifiques nécessaires à la préservation et gestion durable de Khaya anthotheca dans le sud-ouest de la République Centrafricaine via l’amélioration des connaissances sur son écologie. Pour y parvenir, des inventaires forestiers ont été effectués dans les Permis d’Exploitation et d’Aménagement (PEA) des entreprises forestières CentraBois (PEA 192) et Timberland (PEA188). Pour toutes les caractéristiques dendrométriques calculées en fonction des concessions et des classes de diamètre, le PEA 188 de Timberland est largement dominant. La densité moyenne des individus adultes est de 0,10 pieds/ha sur le PEA 192 et de 12 pieds/ha sur le PEA 188 avec le même coefficient de variation (cv) de 112,7%. La surface terrière (m2/ha) varie de 0,86 sur le PEA 192 à 3,78 sur le PEA 188 avec des cv respectifs de 60,2% et 66,4%. La densité de régénération moyenne varie de 3,52 plants/ha sur le PEA 192 à 12,19 plants/ha sur le PEA 188. Les courbes dendrométriques sont exponentielles décroissantes dans les deux concessions. Des travaux de recherches sur la régénération artificielle de K. anthotheca sont importantes pour définir des mesures de préservation dans ces zones.Mots clés : Concessions forestières, inventaires, régénération, gestion durable.   English Title: Structural characterisation of natural populations of Khaya anthotheca (Welw.) C.DC in the forest concessions of South-West of Central African RepublicThe objective of this study is to provide scientific information necessary for the preservation and sustainable management of Khaya anthotheca in the south-west of the Central African Republic by improving knowledge of its ecology. To achieve this, forest inventories were carried out in the Logging and Management Permits (PEA) of the forestry companies CentraBois (PEA 192) and Timberland (PEA188). For all dendrometric characteristics calculated according to concessions and diameter classes, Timberland's PEA 188 is largely dominant. The average density of adult individuals is 0.10 tree/ha on PEA 192 and 12 tree/ha on PEA 188 with the same coefficient of variation (CV) of 112.7%. The basal area (m2/ha) varies from 0.86 on PEA 192 to 3.78 on PEA 188 with respective coefficient of variation of 60.2% and 66.4%. The average regeneration density varies from 3.52 plant/ha on the PEA 192 to 12.19 plant/ha on the PEA 188. The dendrometric curves are exponentially decreasing in both concessions. Research on artificial regeneration of K. anthotheca is important to define preservation measures in these areas.Keywords: Forest concessions, inventories, regeneration, sustainable management.

Improved growth and yield of Faba beans (Vicia faba cv. Fiord) by inoculation with strains of Rhizobium leguminosarum biovar. viciae in acid soils in south west Victoria

1994 ◽  
Vol 45 (3) ◽  
pp. 613 ◽  
Author(s):  
JM Carter ◽  
WK Gardner ◽  
AH Gibson
Keyword(s):  
Vicia Faba ◽  
Rhizobium Leguminosarum ◽  
Field Experiments ◽  
Natural Populations ◽  
Acid Soils ◽  
Growth And Yield ◽  
Nitrogen Accumulation ◽  
Commercial Strain ◽  
South West ◽  
Faba Beans

The response of faba beans (Vicia faba L. cv. Fiord) to seed inoculation with eight strains of Rhizobium leguminosarum biovar. viciae was examined in field experiments at six sites on acid soils in south-west Victoria. At two of the sites, two additional strains were examined, and in 1988, 14 strains were examined at one site. Very low natural populations of R. leguminosarum bv. viciae were found at the experimental sites. Most strains resulted in improved early nodulation and increased grain yield at all sites, when compared to inoculation with the commercial strain of rhizobia (SU391). Plant dry matter production and nitrogen accumulation in the plant shoot tissue was also increased at one site during the flowering period by some strains. Large visual differences between plots inoculated with SU391 and other strains were evident at most sites. Most uninoculated treatments were not nodulated and yielded very poorly. Treatments inoculated with the strain SU391 performed similarly to the uninoculated treatments.

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.

STRUCTURAL AND FLORISTIC CHARACTERIZATION OF THE OULED BECHIH FOREST (ALGERIA)

2021 ◽  
Author(s):  
Touafchia Boutheyna ◽  
Kadi Zahia ◽  
Redjaimia Lilia ◽  
Rached-Kanouni Malika
Keyword(s):  
Diversity Index ◽  
Basal Area ◽  
Woody Species ◽  
Quercus Suber ◽  
Average Density ◽  
Quercus Canariensis ◽  
Rational Management ◽  
Sustainable Conservation ◽  
Total Structure

The objective of this study is the rational management of forest ecosystems for sustainable conservation of floristic biodiversity. Two types of analysis are carried out: structural analysis and analysis of the main species. A total of 22 families were identified, divided among 32 species. The dominant woody species are Quercus suber and Quercus canariensis. Fagaceae is the most represented family. The average values of species richness and Shannon diversity index are 4 ± 1.8 and 0.9 ± 0.30 species/plot respectively. The average density of woody species in the Oueld Bechih forest was 158 ± 28 tree/ha with an average basal area of 32.67 ± 0.74m²/ha. The height structure shows that trees in height classes is ≥ 6 has very high density, evidence of almost no natural regeneration. The total structure indicates that larger trees are more abundant. In effect, this work provides a database for the forest, but it represents only one facet to be considered in protecting and restoring it.

scholarly journals POPULATION STRUCTURE AND PRODUCTION OF COPAIBA OLEORESIN BETWEEN VALLEYS AND HILLSIDES OF THE MINING AREA OFTROMBETAS RIVER - PARÁ1

2016 ◽  
Vol 40 (1) ◽  
pp. 51-60 ◽  
Author(s):  
Jonas Gebara ◽  
Antenor Pereira Barbosa ◽  
Isabel Maria Gonçalves Azevedo ◽  
Bruno Oliva Gimenez
Keyword(s):  
Population Structure ◽  
Forest Inventory ◽  
Sustainable Management ◽  
Natural Populations ◽  
Mining Area ◽  
National Forest ◽  
The South ◽  
Potential Production ◽  
Average Value ◽  
Bauxite Ore

ABSTRACT We aimed in this work to study natural populations of copaiba (Copaifera multijuga Hayne) on the Monte Branco mountain at Porto Trombetas-PA, in order to support sustainable management and the exploitation of oleoresin from copaiba. We studied the population structure of copaiba on hillsides and valleys of the south face of Monte Branco, within Saracá Taquera National Forest, where bauxite ore was extracted in the biennium 2013-2014 by Mineração Rio do Norte (MRN). We produced a 100% forest inventory of the specie and of oleoresin extraction in order to quantify the potential production of the remaining area. The density of copaiba individuals with DBH > 30 cm was 0.33 individuals per hectare in the hillside and 0.25 individuals per hectare in the valley. Both environments presented a density of 0.28 individuals per hectare. The average copaiba oleoresin yield was 0.661±0.334 liters in the hillside and 0.765±0.280 liters in the valley. The average value of both environments together (hillside and valley) was 0.714±0.218 liters. From all individuals with DBH over 30 cm, 38 (58%) produced some amount of oleoresin, averaging 1.113±0.562 liters in the hillside, 1.329±0.448 liters in the valley and 1.190±0.355 liters in both environments together. The results show the need for planning the use of the surroundings of the study area in order to reach the required volume of copaiba to make feasible the sustainable management of oleoresin extraction in the region.

scholarly journals Status of Astragalus cornutus Pall. populations in the Samara Region

2018 ◽  
Vol 7 (1) ◽  
pp. 37-41
Author(s):  
Valentina Nikolaevna Ilina
Keyword(s):  
Population Change ◽  
Natural Populations ◽  
Average Density ◽  
Effective Density ◽  
Anthropogenic Factors ◽  
Efficiency Criterion ◽  
Protection Measures ◽  
Additional Protection ◽  
Geographical Populations ◽  
Satisfactory State

This paper examines features of the demographic structure of natural populations of a rare representative of the steppe flora Astragalus cornutus Pall. (Fabaceae). The rarity of the species makes it necessary to include it in the Red Books of the Russian Federation and some steppe regions. In the Samara Region, species populations require additional protection in connection with the peculiarities of biology and ecology, a significant anthropogenic load on communities, and a reduction in the number of habitats. We studied the features of the structure of populations in the Samara Trans-Volga Region. A total of 84 cenopopulations were surveyed, tendencies of population change, features of demographic and spatial structure were revealed. The structure of populations is affected by the ecological and phytocenotic conditions of the environment and anthropogenic factors. The replacement and recovery of individuals in A. cornutus populations is slow. The ontogenetic structure of populations has a fluctuation dynamics. Assessment of the studied geographical populations by L.A. Zhivotovsky efficiency criterion (2001) showed that they are all mature. Specific cenopopulations of A. cornutus are aging (5%) and old (8%). The average density of individuals is about 3 individuals/m. The average effective density is 2,4 individuals/m, the largest - 4,1, the smallest - 1,3. The condition of all studied populations (even in a satisfactory state) on the territory of the Samara Region causes alarm. Populations of the species in the region need additional protection measures.

The relationship between animal foraging and nutrient patchiness in south-west Australian woodland soils

Soil Research ◽  
2003 ◽  
Vol 41 (4) ◽  
pp. 665 ◽  
Author(s):  
Mark J. Garkaklis ◽  
J. S. Bradley ◽  
R. D. Wooller
Keyword(s):  
Soil Nutrients ◽  
Surface Soil ◽  
Natural Populations ◽  
Water Infiltration ◽  
European Settlement ◽  
South West ◽  
Bettongia Penicillata ◽  
Australian Continent ◽  
The Relationship ◽  
Preferential Water

The woylie (Bettongia penicillata) was once common and abundant over the southern third of the Australian continent. Since European settlement the range of this rat-kangaroo has become reduced by more than 97%, and until the early 1990s, only 3 small natural populations remained, all in south-western Australia. These medium-sized (c. 1 kg) marsupials create a large number of diggings as they forage for the hypogeous fruiting bodies of ectomycorrhizal fungi upon which they feed. The effect of such foraging activity on the availability of plant nutrients in the vicinity of such diggings was evaluated in simulated digging experiments. Available nitrate, ammonium, and sulfur decreased significantly 3 years after diggings were constructed and had filled in, whereas phosphorus, potassium, iron, and organic carbon remained unchanged. The results suggest that preferential water infiltration via woylie diggings leads to a decrease in those soil nutrients that are susceptible to leaching and indicates that digging vertebrates may influence the distribution of surface soil nutrients.

Genetic variability and diversity analysis for yield and its components in wheat (Triticum aestivum L.)

2017 ◽  
Author(s):  
Vichitra Kumar Arya ◽  
Jogendra Singh ◽  
Lokendra Kumar ◽  
Rajendra Kumar ◽  
Punit Kumar ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Genetic Variability ◽  
Grain Yield ◽  
Coefficient Of Variation ◽  
Block Design ◽  
Scientific Information ◽  
Triticum Aestivum L ◽  
Flowering Plant ◽  
Cluster Distance ◽  
Spike Number

Forty nine genotypes of wheat were studied for generating scientific information on nature and magnitude of genetic variability and diversity for designing breeding programme. The experiment was conducted in randomized complete block design in three replications. The data were recorded on days to 50% flowering, plant height, peduncle length, number of productive tillers per plant, days to maturity, spike length, number of spikelets per spike, number of grains per spike, 1000-grain weight, biological yield per plant, grain yield per plant, harvest index and gluten content. Analysis of variance revealed significant differences among the genotypes for all the characters under study. The highest estimates of phenotypic coefficient of variation (PCV) and genotypic coefficient of variation (GCV) were observed for grain yield per plant. High heritability coupled with high genetic advance was observed for grain yield per plant. Based on D2 –Statistics, 49 genotypes were grouped into eight clusters. The highest inter-cluster distance was found between cluster VII and VIII followed by III and VII. This indicates that genotypes included in these clusters possess wide genetic diversity. Grain yield per plant (31.46%) showed highest contribution towards genetic divergence; therefore, this character was major determinant of genetic diversity. On the basis of divergence and cluster mean it may be suggested that maximum heterosis and good recombinants could be obtained in crosses between genotypes of cluster VIII, VII and III in varietal improvement programme. Thus, crosses between the genetically diverse genotypes of cluster VIII with genotypes HUW 655, HP 1937, DBW 88 and HD 3058 and cluster VII with genotypes like HP 1938, HUW 656, K1006, DBW83, DBW 84, K1004, UP2822 and NW5050 are expected to exhibit high heterosis and are also likely to produce new recombinants with desired traits.

scholarly journals Estimation Of The Value Of Goods And Services Produced By Protected Areas: Case Of The Ndock Sare Community Forest In Senegal

2021 ◽  
Vol 17 (43) ◽  
pp. 282
Author(s):  
Mamadou Ndiaye ◽  
Saboury Ndiaye ◽  
Sérigne Modou Sarr ◽  
Malick Diouf
Keyword(s):  
Decision Making ◽  
Sustainable Management ◽  
Basal Area ◽  
Policy Dialogue ◽  
Existence Value ◽  
Community Forests ◽  
Goods And Services ◽  
Vegetation Surveys ◽  
Decision Making Processes ◽  
Ecological Importance

The community forests of Senegal, and particularly those of the Groundnut Basin, play an important role in the lives of rural populations. They are significant sources of supply of various products and services. But despite their economic and ecological importance, community forests have never been the subject of an economic evaluation. This is likely to obscure the decision-making auspices of sustainable management of community forests. This study, based on vegetation surveys and socio-economic surveys, assessed the value of ecosystem goods and services. The results of the analysis showed that the forest has 21 species distributed among 08 families and that this diversity varies from one area to another. With this specific diversity, the basal area is evaluated at 2.64 m2/ha and the cover of 6081.17 m²/ha for a density of 327 individuals per hectare. The forest has a carbon storage capacity evaluated at 15.32 tons. The goods and services of the forest were estimated at 3,391,757 F CFA/year. This value is divided between direct uses estimated at 1,236,575 F CFA/year, indirect uses of 168,495 F CFA/year and an existence value of 1,986,687 F CFA/year. The study also showed that the exploitation of the forest is the most viable management option, as strict conservation imposes a social cost of 370,058 CFA francs per year on the population. In the context of decentralization, these results can serve as a basis for policy dialogue and decision-making processes on the sustainable management of forest resources

scholarly journals Dynamique des peuplements ligneux dans le Parc National de Manda, au sud du Tchad

2019 ◽  
Vol 42.1 ◽  
pp. 7139-7152
Author(s):  
Guiguindibaye MADJIMBE ◽  
Goy SARADOUM ◽  
Touroumgaye GOALBAYE ◽  
Esaïe WAYA ◽  
Jonathan POUNAKOUMNA
Keyword(s):  
National Park ◽  
Basal Area ◽  
Average Density ◽  
Anthropogenic Pressure ◽  
Average Volume ◽  
Specific Composition ◽  
Gradual Evolution ◽  
Standing Timber ◽  
Composition Spécifique ◽  
Structure Des Peuplements

1 RÉSUMÉ La présente étude a pour but d’étude la dynamique des peuplements ligneux dans le Parc National de Manda. Elle vise à déterminer les caractéristiques structurales, la composition spécifique et la régénération des peuplements ligneux. Quatre sites ont été implantés depuis 2012. Nous avons procédé à la caractérisation des peuplements ligneux par des relevés dendrométriques. La flore ligneuse dans l’ensemble des sites est riche de 87 espèces reparties en 56 genres et 22 familles. Les sites 1 et 2 ont des effectifs plus élevés en 2019 comparativement en 2014 et en 2012. Une forte régénération s’est effectuée durant l’année 2019. Contrairement aux sites, 1 et 2, les sites 3 et 4 présentent pour l’année 2019 une forte baisse des effectifs de jeunes plants. Ces jeunes plants sont très sensibles non seulement à la disponibilité des ressources en eau pour franchir la saison sèche mais aussi à l’intensité et à la fréquence de passage des feux. Les résultats ont permis de noter que la densité moyenne entre 2012 et 2014 s’est accrue et à partir de 2014 elle s’est stabilisée. La surface terrière par hectare est, en moyenne de 10,12 m2/ha pour 2012 ; 11,16 m2/ha pour l’année 2014 et de 11, 65 m2/ha pour l’année 2019. Pour l’ensemble des sites expérimentaux, on évalue le volume moyen de bois sur pieds à 12,31 m3/ha en 2012, à 12,46 m3/ha en 2014 et 12,08 m3/ha en 2019. Ces valeurs indiquent que les variations de volume moyen de bois sur pieds sont très faibles pour les sites pris dans leur ensemble. Les résultats obtenus, montrent aussi que 8 espèces se situent dans un processus d’évolution régressive et 4 autres dans un processus d’évolution progressive. La structure des peuplements ligneux n’a pas beaucoup évolué en 8 ans mais, elle apparaît fortement tributaire de la topographie et de la pression anthropique. ABSTRACT Dynamic of the woody populations in the National Park of Manda, to the south of Chad The purpose of this study is to study the dynamics of woody stands in the Manda National Park. It aims to determine the structure, specific composition and regeneration of woody stands. Four sites have been established since 2012. We have characterized the woody stands by dendrometric surveys. The woody flora in all sites is rich in 87 species divided into 56 genera and 22 families. Sites 1 and 2 have higher numbers in 2019 compared to 2014 and 2012. Strong regeneration took place in 2019. Unlike sites 1 and 2, sites 3 and 4 present for the year 2019 a sharp decline in the number of young plants; these seedlings are very sensitive not only to the availability of water resources to cross the dry season but also to the intensity and frequency of fire. The results showed that the average density between 2012 and 2014 increased and from 2014 it stabilized. The basal area per hectare is, on average, 10.12 m2 / ha for 2012; 11.16 m2 / ha for the year 2014 and 11, 65 m2 / ha for the year 2019. For all the experimental sites, the average volume of standing timber is estimated at 12.31 m3/ ha in 2012, 12.46 m3 / ha in 2014 and 12.08 m3 / ha in 2019. These values indicate that variations in average volume of standing timber are very low for sites taken as a whole. The results obtained also show that 8 species are in a process of regressive evolution and 10 in a process of gradual evolution. The structure of woody stands has not changed much in 8 years, but it appears highly dependent on topography and anthropogenic pressure.

scholarly journals Endophytic fungi associated with natural populations of Vanilla species in south-west Colombia

Lankesteriana ◽  
2013 ◽  
Author(s):  
Ana Teresa Mosquera Espinosa ◽  
J. Tupac Otero ◽  
Nicola S. Flanagan
Keyword(s):  
Endophytic Fungi ◽  
Natural Populations ◽  
South West
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