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ArticleCharacteristics of growth and heartwood formation in planted teak in South China
XV World Forestry Congress, 2-6 May 2022
2022Also available in:
No results found.Dominant trees in 31 and 32 years old teak plantation were selected for trunk analysis to study the growth process and heartwood formation characteristics by scanning the disk with scanner and measuring the data with software. The results showed that tree height at the early growth stage (1 to 8 years) was more than that of the DBH (1 to 4 years) for 4 years. The middle growth stage of DBH (5 to 18 years) (stable growth stage) was longer than that of tree height (9 to 13 years) for 9 years. The average growth curve of the volume was not intersected with annual growth curve, which indicated that 31 years old teak plantation had not reached maturity age. The total number of annual rings and the number of heartwood rings were decreased with the increase of tree height, while the number of sapwood rings at different heights changed little. The number of sapwood rings below 16 m of trunk varied about 8 rings, and began to decrease gradually over 16 m. The diameters of xylem, heartwood and sapwood at different heights showed the same trend as the ring, the sapwood width below 22 m was stable, and decreased gradually above 22 m. Affected by taperingness, the heartwood area was larger than sapwood below 10 m, but smaller above 10m. There was a significant positive correlation between the number of heartwood rings with xylem age, diameter of heartwood and xylem diameter (p < 0.01). The growth of dominant tree DBH and tree height in teak plantation began to decline at 18 and 13 years respectively, the current growth and predicted maximum growth were still far lower than cultivation target (DBH ≥ 60cm). The heartwood formation of teak was positively correlated with the diameter growth. It is necessary to breed and utilize teak varieties with small taper and thinning should be done from 13 years for reserved dominant trees. Keywords: Tectona grandis L. f.; dominant tree; stem analysis; growth process; heartwood; sapwood ID: 3619031 -
DocumentImprovements in airborne laser scanning-based forest structural type assessment
XV World Forestry Congress, 2-6 May 2022
2022Also available in:
No results found.Accurate forest structural types (FSTs) assessment helps to provide valuable support tools to distinguish different structures in forest stands and formulate effective management decisions. We used data from -Boreal, Mediterranean and Atlantic- biogeographical regions and developed reliable methodologies for the FSTs assessment. First, we used the Gini coefficient (GC) of tree size inequality and evaluated the effects of plot size, stand density and point density of the airborne laser scanning (ALS) on the ALS-assisted GC estimations in Boreal conditions. Second, we used four structural variables -quadratic mean diameter (QMD), GC, basal area larger than mean (BALM) and stand density (N)- from the three biogeographical regions and developed region-independent methods for the FSTs assessment. Lastly, we detected FSTs directly from ALS data, predicted the aboveground biomass (AGB) at each FST, and compared it with the AGB prediction without pre-stratification. Results showed that (a) plot size had a greater effect on the ALS-assisted GC estimation as compared to the stand and point density and 250-450 m2 plot size is the optimal plot size for reliable ALS-assisted GC estimation. (b) GC and BALM were the most important descriptors for the FSTs assessment and single storey, multi-storey and reversed-J types of forest structures can be separated by lower, medium and high values of GC and BALM, respectively, while QMD and N were relevant to separate young/mature and sparse/dense subtypes.(c) We observed marginal improvements in the AGB predictions from the direct ALS-based FSTs but identified critical differences in the selection of ALS metrics by the prediction models such as higher percentiles are more relevant in the open canopies while cover metrics and average percentiles are important in the closed canopies. These results are thus very useful in improving our understanding on the causality behind the choice of ALS predictors in structurally complex forests. Keywords: Sustainable forest management, Monitoring and data collection, Biodiversity conservation, Research ID: 3621963 -
ArticleThe tropical biomass & carbon project– An app for forest biomass and carbon estimates
XV World Forestry Congress, 2-6 May 2022
2022Also available in:
No results found.This article introduces the project called Tropical Biomass & Carbon – TB&C, available on the permanent link www.tropicalbiomass.com. The App requires input attributes of the forest stand or diameter class easily obtained, being: smallest and largest diameters, number of trees ha-1, and parameters of the diameter distribution. The output attributes are at the stand and tree levels. At stand level, the App delivers mean aboveground biomass (AGB) and carbon (AGC), in Mg ha-1, as well as their confidence intervals (CIs) and uncertainties. The tree-level outputs are AGB and diameter for every tree in the stand. The project TB&C comprises four Brazilian forest (and non-forest) formations: Campinarana, Floresta estacional, Floresta ombrofila, and Savana. This article aims to disclose the algorithm written for the TB&C App. This phase counts on a standardized database of 1,428 trees with dry AGB destructively measured. Model uncertainties were incorporated into the modeling process. In addition to its reliability, we cite as great advantages of the TB&C App; (i) simplicity and a user-friendly layout, (ii) AGB and AGC estimates provided along with robust CIs, and (iii) estimates at the stand and tree levels with consistent totals. As a secondary product, the project TB&C delivers a dataset of 64,000 simulated plots, informing dry AGB, tree density, basal area, Lorey’s height, and shape of the diameter distribution. Keywords: Tropical Forest, Aboveground biomass, Uncertainty analysis, Stand- and tree-level, estimates, Web application ID: 3623771
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