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Thomas Seifert published an article in April 2017.
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(2008 - 2017)
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Article 1 Read 0 Citations The effect of surface fire on tree ring growth of Pinus radiata trees Published: 14 April 2017
Annals of Forest Science, doi: 10.1007/s13595-016-0608-8
Pinus radiatatrees showed significantly reduced basal area increments and increased latewood/earlywood ratios, when their stem was charred by surface fires even if no needle damage occurred. An interaction of fire damage and precipitation on growth was observed. Heat from forest fires is able to penetrate beyond the bark layer and damage or completely kill a tree’s cambium. Short-term growth reductions following surface fires have been reported for some species. However, most studies have in common that they describe a compound effect of stem and foliage damage. This study investigated the impact of surface fires on the radial growth of Pinus radiata, where only the stem of trees was charred, while no needle damage was recorded. Tree ring measurements were performed on cores obtained at breast height. Analysis of variance and tests, based on annual basal area increment values were calculated to quantify pre- and post-fire growth differences of tree ring width and latewood/earlywood ratios. The analysis revealed significant growth reductions following a surface fire on P. radiata in the year on which the fire occurred as well as in the following year. As a consequence of the fire, basal area increment and latewood/earlywood ratios were significantly reduced. An interaction of fire damage and precipitation on growth was observed. The obtained results show how fires without crown damage can affect growth and tree ring structure of P. radiata trees and indicate that stem char could be associated with a significant decrease in ring width and latewood/earlywood ratio.
Article 2 Reads 0 Citations Trade-off relationships between tree growth and defense: a comparison of Ocotea bullata and Curtisia dentata following b... Published: 01 November 2016
Trees, doi: 10.1007/s00468-016-1487-1
Article 1 Read 0 Citations A method for determining knotty core sizes of standing Pinus patula trees based on tree ring sampling Published: 01 June 2016
Dendrochronologia, doi: 10.1016/j.dendro.2016.02.003
The objectives of this study were to develop and assess a method of using tree ring measurements in standing pruned Pinus patula trees for modelling the knotty core of the pruned section of a tree and to assess variability in knotty core diameters in the tree stem. A total of 170 trees from 17 compartments on a wide variety of growth sites from the Mpumalanga escarpment in South Africa were selected and destructively sampled. We show that ring width measurements at breast height can be used to predict growth in the upper pruned section which in turn can be used to reconstruct the internal knotty core through the full pruned section of the log.Analysis of variation for the entire data set from ring width measurements showed that there was far greater variation in knotty core percentages (the percentage of diameter occupied by knotty core) between different compartments than within compartments. Within a tree, the knotty core percentages between three stem sections, 0.0–2.4 m, 2.4–4.8 m, and 4.8-7 m, differed significantly. As expected the knotty core percentages were found to increase from the bottom section (49.1%) to the top section (65.4%).A comparison of the actual measured knotty core size and the modelled knotty core size of a sub-sample of trees showed only a modest relationship (R2 = 0.62). Reasons for this might be variability in pruning quality, inaccurate pruning records, nodal swellings, and the methodology used to measure the actual knotty core sizes.Knowledge of knotty core sizes can be used as a decision aid in the forest and forest products industry.
Article 2 Reads 4 Citations Aboveground Biomass and Carbon in a South African Mistbelt Forest and the Relationships with Tree Species Diversity and ... Published: 08 April 2016
Forests, doi: 10.3390/f7040079
Biomass and carbon stocks are key information criteria to understand the role of forests in regulating global climate. However, for a bio-rich continent like Africa, ground-based measurements for accurate estimation of carbon are scarce, and the variables affecting the forest carbon are not well understood. Here, we present the first biomass study conducted in South Africa Mistbelt forests. Using data from a non-destructive sampling of 59 trees of four species, we (1) evaluated the accuracy of multispecies aboveground biomass (AGB) models, using predictors such as diameter at breast height (DBH), total height (H) and wood density; (2) estimated the amount of biomass and carbon stored in the aboveground compartment of Mistbelt forests and (3) explored the variation of aboveground carbon (AGC) in relation to tree species diversity and structural variables. We found significant effects of species on wood density and AGB. Among the candidate models, the model that incorporated DBH and H as a compound variable (DBH2 × H) was the best fitting. AGB and AGC values were highly variable across all plots, with average values of 358.1 Mg·ha−1 and 179.0 Mg·C·ha−1, respectively. Few species contributed 80% of AGC stock, probably as a result of selection effect. Stand basal area, basal area of the ten most important species and basal area of the largest trees were the most influencing variables. Tree species richness was also positively correlated with AGC, but the basal area of smaller trees was not. These results enable insights into the role of biodiversity in maintaining carbon storage and the possibilities for sustainable strategies for timber harvesting without risk of significant biomass decline.
Article 1 Read 0 Citations Below- and aboveground architecture of Androstachys johnsonii prain: topological analysis of the root and shoot systems Published: 30 May 2015
Plant and Soil, doi: 10.1007/s11104-015-2527-0
Article 1 Read 9 Citations Competition effects in an afrotemperate forest Published: 30 September 2014
Forest Ecosystems, doi: 10.1186/s40663-014-0013-4
Information about competition responses is mainly available for monospecific stands or mixed stands with a small number of species. Studies on complex multi-species and highly structured forest ecosystems are scarce. Accordingly, the objective of this study was to quantify competition effects and analyse competition responses in a species-diverse afrotemperate forest in South Africa, based on an observational study with mapped tree positions and long-term diameter increment records.