Root Growth Was Enhanced in China Fir (Cunninghamia lanceolata) after Mechanical Disturbance by Ice Storm

Accurate estimation of forest biomass and its growth potential could be important in assessing the mitigation potential of forest for climate change. However, severe mechanical disturbance such as stem breakage imposed significant changes to tree individuals in biomass structure, which could bring new inaccuracy to biomass estimation. In order to investigate the influence of severe mechanical disturbance on tree biomass accumulation and to construct accurate models for biomass and carbon storage estimation, this paper analyzed the relationship between tree size and biomass for China fir (Cunninghamia lanceolata (Lamb.) Hook) which suffered stem breakage from, and survived, an ice storm. The performance of independent variables diameter (D) and height (H) of China fir, were also compared in biomass estimation. The results showed that D as an independent variable was adequate in biomass estimation for China fir, and tree height was not necessary in this case. Root growth was faster in China fir which had suffered breakage in the main stem by the ice storm, than China fir which were undamaged for at least 7 years after the mechanical disturbance, which, in addition to biomass loss in stem, caused changes in the allocation pattern of the damaged trees. This suggests biomass models constructed before severe mechanical disturbance would be less suitable in application for a subsequent period, and accurate estimations of biomass and forest carbon storage would take more effort.

STUDY OF THE VIABILITY OF ALEPPO PINE TREES BY USING PHF INDEX

This work, which was conducted in the Chettaba forest about the viability of the stands can be given by the PHF index, a three-digit index that gives a judgment of the position of the tree (in relation to the others and thus indicating the dominance and the stage of competition or exposure to the dominant stage), of the general shape of the crowns, and of the shape of the shafts, it allows a more detailed silvicultural interpretation to predict the future of the stand and ultimately deduce the viability of the stands. Thus, there is an essential need for a study to be conducted in this regard to understand the existing problems and to bring about proposals on the appropriate intervention in logged surface. The slenderness coefficient of a tree is defined as the ratio of the total height (H) to the diameter at 1.3 m above ground level (d). For the stand level, the slenderness coefficient is calculated using the root mean square diameter and the average tree height as (H/D). It is well known that there is a direct relationship between the stand slenderness coefficient and the risk of stem breakage. It is well known that there is a direct relationship between the stand slenderness coefficient and the risk of stem breakage or tree fall due to abiotic factors such as wind or snow. Sustainability monitoring is crucial to the credibility, validation, value of the options implemented and should be considered early on in the planning process this allows us to say that these stands are stable in the forest and always in the 6 plots studied. Analyses results show a mid-viability for the forest and more of individual listed present instability which is indicated by a medium stability of forests stand’s quality (PHF = 123) and a slenderness coefficient (H/D = 34.47).

Effect of Stem Snapping on Aspen Timber Assortment Recovery in Hemiboreal Forests

Post-disturbance salvage logging mitigates economic loss after windthrow, and the value of salvaged timber is strongly linked to its quality and dimensions. We studied the occurrence of wind-induced damage of aspen in the hemiboreal forests of Latvia based on data from the National Forest Inventory and additional measurements. Individual tree data from three re-measurement periods were linked to follow a tree condition (live, broken, uprooted) and to link tree characteristics to a respective snag. Three linear models were developed to assess factors affecting the snapping height. An assortment outcome was calculated for undamaged and salvaged trees using the bucking algorithm, and timber value was calculated at three price levels. Wind-induced damage occurred for 3.4–3.6% of aspen trees, and among these, 45.8–46.6% were broken. The mean height of the broken trees was 27.3 ± 0.9 m, and it was significantly higher (both p < 0.01) compared to the height of undamaged and uprooted trees. The tested models indicated tree height as the main explanatory variable for relative snapping height, with higher trees having a lower point of the stem breakage. The other significant factor was the forest type group, indicating that trees growing on dry mineral soils had lower relative snapping height than trees growing on drained mineral soils. Stem breakage significantly (p < 0.001) reduced the volume of assortments, as compared to the volume of undamaged trees. Relative volume loss of sawlogs showed a logarithmic trend with a steep increase up to snapping height of 6 m, and it correlated tightly (r = 0.83, p < 0.001) with relative value loss of the total stem. Timber value loss had a strong, positive relation to tree diameter at breast height and fluctuated by 0.4% among different price levels. The mean volume reduction was 37.7% for sawlogs, 11.0% for pallet blocks, and 8.9% for technological wood.

Risk factors for femoral stem breakage: an analysis of the AOANJRR results

Introduction: Breakage of the femoral stem component of a total hip replacement is now uncommon but continues to be seen with certain stem designs and in certain patient groups. Data previously published on this topic has been limited, either gathered from a single surgeon or centre, or included only a single stem design. Methods: We reviewed the data from the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR), identified and analysed 143 stem breakages over a period of 16 years, covering 44 different stem designs. Results: Our data confirms previously published findings that risk factors for stem breakage include patient age at implantation of under 70, male gender, as well as the use of exchangeable necks. We found no association with initial diagnosis, or type of acetabular component implanted. We did however also find, excluding exchangeable neck designs, that after 4.5 years a cemented stem had a significantly higher risk of breakage then a cementless stem. Discussion: To our knowledge this is the 1st paper to suggest cemented fixation as a specific risk factor for stem breakage. The analysis of rare complications such as stem breakage is only possible through large data collection systems such as the AOANJRR. Whilst there have been recent advances in materials and manufacturing techniques, we recommend that surgeons are aware of all the specific risks when considering implant choices for individual patients.

Wind-induced stem breakage height effect on potentially recovered timber value: case study of the Scots pine (Pinus sylvestris L.) in Latvia

In Europe, salvage-logging is a common management activity to partially recover economic value from wind disturbed forests. In the near future, wind damage to forests is predicted to increase due to climate change. Therefore, an economic assessment of wind damage effects on recovered timber value is useful information in the decision-making process. In this study, we aim to assess the influence of different stem damage heights on the monetary value of recovered timber. We simulated stem breakage at three heights for the Scots pine (Pinus sylvestris L.): 3, 5, and 7 m. For comparison, we used an uprooted tree without stem breakage. Our results revealed that the most negative influence on the recovered timber value was stem breakage at 3 m, which decreased the monetary value by 35%. The stem breakage at 5 and 7 m decreased the recovered timber value by 9–10%. Over the analysed period (2006–2017), no significant differences in the monetary value of the recovered timber were found between uprooted lumber and stems with breakage at 5 and 7 m. The price fluctuations in the market have a significant influence on the recovered timber value, which might cause a larger decrease in monetary value than stem breakage.