Dead wood volume to dead wood carbon: the issue of conversion factors

Requirements for emission reporting under the Kyoto protocol demand an estimate of the dead wood carbon pool in forests. The volume of dead wood consists of coarse woody debris, smaller woody debris and dead roots. The measurement of dead wood volume was included in the most recent National Forest Inventory in Switzerland. To convert dead wood volume into carbon two conversion factors are required: (a) carbon (C) concentration and (b) wood density. So far internationally accepted default values for C concentration (50%) and for wood density (density of alive trees) were used as default values to estimate dead wood carbon, since local measurements were lacking. However, in a field study at 34 sites in Switzerland, the C concentration and density of CWD from Picea abies and Fagus sylvatica of four decay classes were measured recently. The results showed that C concentration in CWD differed significantly between species but did not change due to decay class. The density of CWD decreased significantly with an increase in decay class and it also differed between species. The decrease in CWD density was more pronounced for F. sylvatica than for P. abies. We assessed correlations between climate attributes and CWD density using regression analysis. The modeled densities and measured C concentrations were then expanded with the help of CWD volume data from the NFI3. Spruce CWD and thus spruce CWD carbon is much more abundant in Swiss forests than beech CWD carbon. The majority of spruce CWD is located in the Alps and Pre-Alps. The CWD volume from P. abies was 10 times higher than that from F. sylvatica. Thus, changes in conversion factors for P. abies CWD affected the overall estimate of dead wood carbon in Swiss forests much more than changes in conversion factors for F. sylvatica CWD. Current improvements in CWD conversion factors decreased the estimated amount of spruce CWD carbon by 23.1% and that of beech by 47.6%. The estimated amount of CWD carbon in Swiss forests is decreased by 31%. Since improved estimation methods are currently not applied to smaller woody debris and dead root material, the estimated amount of dead wood carbon is only reduced by 15%. Improving conversion factors for all dead wood fractions would presumably decrease the amount of dead wood carbon by additional 16

Tree biomass in the Swiss landscape: nationwide modelling for improved accounting for forest and non-forest trees

Trees outside forest (TOF) can perform a variety of social, economic and ecological functions including carbon sequestration. However, detailed quantification of tree biomass is usually limited to forest areas. Taking advantage of structural information available from stereo aerial imagery and airborne laser scanning (ALS), this research models tree biomass using national forest inventory data and linear least-square regression and applies the model both inside and outside of forest to create a nationwide model for tree biomass (above ground and below ground). Validation of the tree biomass model against TOF data within settlement areas shows relatively low model performance (R 2 of 0.44) but still a considerable improvement on current biomass estimates used for greenhouse gas inventory and carbon accounting. We demonstrate an efficient and easily implementable approach to modelling tree biomass across a large heterogeneous nationwide area. The model offers significant opportunity for improved estimates on land use combination categories (CC) where tree biomass has either not been included or only roughly estimated until now. The ALS biomass model also offers the advantage of providing greater spatial resolution and greater within CC spatial variability compared to the current nationwide estimates

Development of a botanical plant protection product from Larix by-products to protect grapevine from Plasmopara viticola

Extracts from European Larch (Larix decidua) were shown to be efficient to control grapevine downy mildew (Plasmopara viticola) under controlled and field conditions. Larixyl acetate and larixol were identified as the active compounds

Evaluation of a large-scale forest scenario model in heterogeneous forests: a case study for Switzerland

Large-scale forest scenario models are widely used to simulate the development of forests and to compare the carbon balance estimates of different countries. However, as site variability in the application area often exceeds the variability in the calibration area, model validation is important. The aim of this study was to evaluate the European Forest Information Scenario model (EFISCEN). As Switzerland exhibits high spatial and climatic diversity, it was taken as a case study. The model output was compared to measured data in terms of initialization, estimation of growing stock, stand age, increment, management, and natural mortality. Comparisons were done at the country level, but also for regions and site classes. The results showed that the initialization procedure of EFISCEN works well for Switzerland. Moreover, EFISCEN accurately estimated the observed growing stock at the country level. On a regional level, major differences occurred. In particular, distribution of the harvesting amounts, mortality, and age-class distribution deviated considerably from empirical values. For future model applications, we therefore propose to define the required harvesting level not per country, but to specify it for smaller regions. Moreover, the EFISCEN simulations should be improved by refining the mortality function and by incorporating more flexibility in forest management practices

The symmetry of competitive interactions in mixed Norway spruce, silver fir and European beech forests

Questions: We aim for a better understanding of the different modes of intra- and inter-specific competition in two- and three-species mixed-forests. How can the effect of different modes of competitive interactions be detected and integrated into individual tree growth models? Are species interactions in spruce–fir–beech forests more associated with size-symmetric or size-asymmetric competition? Do competitive interactions between two of these species change from two- to three-species mixtures? Location: Temperate mixed-species forests in Central Europe (Switzerland). Methods: We used data from the Swiss National Forest Inventory to fit basal area increment models at the individual tree level, including the effect of ecological site conditions and indices of size-symmetric and size-asymmetric competition. Interaction terms between species-specific competition indices were used to disentangle significant differences in species interactions from two- to three-species mixtures. Results: The growth of spruce and fir was positively affected by increasing proportions of the other species in spruce–fir mixtures, but negative effects were detected with increasing presence of beech. We found that competitive interactions for spruce and fir were more related to size-symmetric competition, indicating that species interactions might be more associated with competition for below-ground resources. Under constant amounts of stand basal area, the growth of beech clearly benefited from the increasing admixture of spruce and fir. For this species, patterns of size-symmetric and size-asymmetric competitive interactions were similar, indicating that beech is a strong self-competitor for both above-ground and below-ground resources. Only for silver fir and beech, we found significant changes in species interactions from two- to three-species mixtures, but these were not as prominent as the effects due to differences between intra- and inter-specific competition. Conclusions: Species interactions in spruce–fir–beech, or other mixed forests, can be characterized depending on the mode of competition, allowing interpretations of whether they occur mainly above or below ground level. Our outcomes illustrate that species-specific competition indices can be integrated in individual tree growth functions to express the different modes of competition between species, and highlight the importance of considering the symmetry of competition alongside competitive interactions in models aimed at depicting growth in mixed-species forests

Does Age Affect the Outcomes of Core Decompression for the Treatment of Kienböck Disease?

Background: Core decompression of the distal radius is a minimally invasive technique that has demonstrated good clinical outcomes in the treatment of Kienböck disease. However, the effectiveness of core decompression has not been compared in different age groups. The aim of this study is to compare the outcomes of core decompression in patients <45 years of age to those ≥45 years of age. Methods: This retrospective study included 36 patients with Kienböck disease who were treated with core decompression over a 20-year period. The mean follow-up was 7 years. Outcome measures included visual analogue scale pain score (VAS), active range of flexion/extension at the wrist, grip strength, and modified Mayo wrist score. The patients were divided into two age groups namely <45 years (younger group; n = 22) and ≥45 years (older group; n = 12) and the outcome measures were compared between the two age groups. Results: There were no statistically significant differences between the outcomes of the two age groups. Conclusion: The outcomes of core decompression of the distal radius for Kienböck disease in older patients (≥45 years) are favorable and similar to those seen in younger patients (<45 years). Level of Evidence: Level III (Therapeutic)

Projecting effects of intensified biomass extraction with alternative modelling approaches

The effect of intensified biomass extraction on forest ecosystems is a timely question since harvest residues are increasingly utilised to produce energy and the impacts of the changed management practises are not always well understood. We compared two different modelling approaches, the MOTTI-YASSO and the EFIMOD-ROMUL model combinations, with respect to the simulated impacts of the biomass extraction in final felling on subsequent biomass and soil carbon stocks. Simulations following the latest silvicultural recommendations over a rotation were made for six Finnish forest sites varying in fertility, tree species and latitude. Model-projected effect of the intensified biomass extraction was larger with EFIMOD-ROMUL than with MOTTI-YASSO. The soil model ROMUL projected slower decomposition of organic matter than YASSO at all studied sites, which made the effect of biomass extraction on soil larger with EFIMOD. The process-based model EFIMOD-ROMUL includes feedback from soil nutrient status to productivity. With EFIMOD-ROMUL, the intensified biomass extraction decreased slightly the simulated growth of the forests and thereby the biomass carbon stock and litter input to the soil. With the empirical MOTTI model, the intensity of the simulated biomass extraction did not affect forest growth. Our results underline the importance of the selection of the modelling approach when projecting the potential effects of forest management practises on forest carbon balance