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ArticleTree size diversity and carbon stock of Tectona grandis (Linn f.) standsin hilltop and valley-bottom of Omo forest reserve, Nigeria
XV World Forestry Congress, 2-6 May 2022
2022Also available in:
No results found.Competition for growth resources contributes to size hierarchy in tree populations. Competition hierarchy of trees is dependent on rate of growth and stages of stand development. However, competition hierarchy in tree population may not cause size symmetry in some stress habitats. Size structure and development of even- aged stand can be influenced by abiotic factors. The study investigated tree size structure and carbon stock of Tectona grandis stands in Valley-Bottom and Hilltop of Omo Forest Reserve. Ten-years-old Teak plantation was delineated into Hilltop and Valley-Bottom stands base on topography. Five (30m x 30m) sample plots were systematically demarcated in each of Hilltop and Valley-Bottom stands. Tree stems were enumerated and densities of both stands were estimated. Total height and diameter-at-breast height were measured using Spiegel Relaskop and Girth tape, respectively, and stem carbon was estimated. Inequality and diversity of stem size of both stands were evaluated. Data collected were analyzed using descriptive, correlation, regression analysis and t-test at α0.05. Stem density of Hilltop (1431.0 stems/ha) was higher than Valley-Bottom stands (1248.0 stems/ha). Mean stem diameter of Valley-Bottom were not significantly different from Hilltop stands. Coefficient of determination (R2 ) of Height-Diameter allometry for Valley-Bottom (0.59) was higher than Hilltop stands (0.45). Diameter distribution of Valley-Bottom and Hilltop expressed bimodality and unimodality, respectively. Inequality was higher in Hilltop than Valley-Bottom for diameter. The stems of Hilltop and Valley-Bottom stands contributed 49.68% and 50.32% of total stem carbon, respectively. Elevation affected the stem size hierarchy and carbon stock distribution of Valley-Bottom and Hilltop habitats. Stems of Valley-Bottom stand could be a good option for carbon sequestration in Omo Forest Reserve. Keywords: Competition hierarchy; Size symmetry; Elevation gradient; Tree height; Tree diameter ID: 3623266 -
ArticleAssessment of enrichment planting of teak (Tectona grandis L.f.) in degraded dry deciduous dipterocarp forest in the Central Highlands, Viet Nam
XV World Forestry Congress, 2-6 May 2022
2022Also available in:
No results found.After years of unsustainable logging, dry deciduous dipterocarp forest (DDDF) has become poor in timber stocks and has been converted to industrial crops such as rubber. The objectives of this study were to assess teak (Tectona grandis L.f.) tree establishment under degraded DDDF conditions and to determine factors that influence the suitability of teak as a forest enrichment tree species. A set of 64 experimental plots of 4900 m2 each was set up and observed for 4–5 years for testing enrichment planting with teak under various combinations of two groups of factors: ecological conditions and forest status. Weighted, non-linear, multivariate regression models were used to detect key factors that influenced the suitability of teak. The results showed that at the age of 4 years the average dominant tree height (defined as 20% of the tallest trees in the experimental plot) reached 11.2, 7.8, 5.3 and 3.8 m for very good, good, average, and poor suitability levels, respectively. Survival rates of planted teak from average to very good suitability levels were over 90%. Six key factors that affected the suitability of teak were waterlogging during the rainy season, altitude, stand volume of the degraded DDDF, soil type, percentage of sand and concentration of P2O5 in the soil. Under the extreme ecological and environmental conditions of the DDDF, enrichment planting with teak gave promising results. Keywords: degraded dipterocarp status, dipterocarp enrichment, teak suitability assessment. ID: 3472951 -
ArticleCharacteristics and dynamics of arbuscular mycorrhizal fungal communities along a chronosequence of teak (Tectona grandis) plantations in Mt. Jianfengling, Hainan Island, China
XV World Forestry Congress, 2-6 May 2022
2022Also available in:
No results found.Teak (Tectona grandis L.f.) is one of the most promising timber species in the tropical and subtropical areas in south China. Arbuscular mycorrhizal (AM) fungi play a crucial role in promoting plant growth, enhancing plant stress resistance and sustaining healthy ecosystem. However, little is known about mycorrhizal status in teak plantations. This study aims to characterize the dynamics of AM fungal communities in the rhizosphere of teak plantations at different ages. Fine roots and rhizosphere soils in teak plantations at varying ages (22, 35, 45 and 55 years old), and the adjacent native grassland without teak plantation (CK) were assessed for soil properties, and AM fungal communities using amplicon sequencing technology. With the increase of stand ages, catalase and ammonium nitrogen in the rhizosphere soil were also increased; soil organic carbon, total phosphorous (P), acid phosphatase, available potassium (AK) and available phosphorus (AP) were first increased and then declined at 55-year-old stand. In total, 12 and 9 AM fungal genera were detected in the rhizosphere soil and in teak root samples, respectively. The OTUs data revealed that AM fungi presented in the rhizosphere soil and roots were mostly belonged to Glomus. In the rhizosphere soil, the relative abundance of Glomus was first increased and then declined, while Gigaspora and Scutellospora were declined, although the diversity and richness of AM fungi showed no significant variation with stand ages. In roots, the composition of AM fungal community and its diversity did not change with stand ages, whereas the richness was increased with the stand age. The monte carlo permutation test indicated that AK, nitrate nitrogen and C/P ratio largely explained the shift in the composition of AM fungal community in the rhizosphere soil. The results demonstrated that AM fungal communities in the rhizosphere soil and teak roots shifted across plantation ages. These changes were largely attributed to the age-induced variation in soil properties. Keywords: Tectona grandis; arbuscular mycorrhizal fungi; stand age; soil properties; plantations ID: 3623633
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