Development of a prototype modeling system to estimate the GHG mitigation potential of forest and wildfire management.

Having recently experienced the three worst wildfire seasons in British Columbia's history in 2017, 2018 and 2021, and anticipating more severe impacts in the future, a key Carbon (C) research priority is to develop reliable models to explore options and identify a portfolio of regionally differentiated solutions for wildfire and forest management. We contribute to this effort by developing a prototype integrated C modeling framework which includes future wildfires that respond to forest stand characteristics and wildfire history. Model validation evaluated net GHG emissions relative to a 'do-nothing' baseline for several management scenarios and included emissions from forest ecosystems, harvested wood products and substitution benefits from avoided fossil fuel burning and avoided emissions-intensive materials. Data improvements are needed to accurately quantify the baseline and scenario GHG emissions, and to identify trade-offs and uncertainties. • A Fire Tolerant scenario included post-fire restoration with planting of climatically suitable fire-resistant species and salvage harvest in place of clearcut harvest.

Post-magmatic fracturing, fluid flow, and vein mineralization in supra-subduction zones: a comparative study on vein calcites from the Troodos ophiolite and the Izu-Bonin forearc and rear arc.

Based on the published data of pillow lava-hosted mineralized veins, this study compares post-magmatic fracturing, fluid flow, and secondary mineralization processes in the Troodos and Izu-Bonin supra-subduction zone (SSZ) and discusses the crucial factors for the development of distinct vein types. Thin section and cathodoluminescence petrography, Raman spectroscopy, fluid inclusion microthermometry, and trace element and isotope (87Sr/86Sr, δ18O, δ13C, Δ47) geochemistry indicate that most veins consist of calcite that precipitated from pristine to slightly modified seawater at temperatures < 50 °C. In response to the mode of fracturing, fluid supply, and mineral growth dynamics, calcites developed distinct blocky (precipitation into fluid-filled fractures), syntaxial (crack and sealing), and antitaxial (diffusion-fed displacive growth) vein microtextures with vein type-specific geochemical signatures. Blocky veins predominate in all study areas, whereas syntaxial veins represent subordinate structures. Antitaxial veins occur in all study areas but are particularly abundant in the Izu-Bonin rear arc where the local geological setting was conducive of antitaxial veining. The temporal framework of major calcite veining coincides with the onset of extensional faulting in the respective areas and points to a tectonic control on veining. Thus, major calcite veining in the Troodos SSZ began contemporaneously with volcanic activity and extensional faulting and completed within ~ 10-20 Myr. This enabled deep seawater downflow and hydrothermal fluid upflow. In the Izu-Bonin forearc, reliable ages of vein calcites point to vein formation > 15 Myr after subduction initiation. Therefore, high-T mineralization (calcite, quartz, analcime) up to 230 °C is restricted to the Troodos SSZ.

Cumulative effects of natural and anthropogenic disturbances on the forest carbon balance in the oil sands region of Alberta, Canada; a pilot study (1985-2012).

BACKGROUND: Assessing cumulative effects of anthropogenic and natural disturbances on forest carbon (C) stocks and fluxes, because of their relevance to climate change, is a requirement of environmental impact assessments (EIAs) in Canada. However, tools have not been developed specifically for these purposes, and in particular for the boreal forest of Canada, so current forest C assessments in EIAs take relatively simple approaches. Here, we demonstrate how an existing tool, the Generic Carbon Budget Model (GCBM), developed for national and international forest C reporting, was used for an assessment of the cumulative effects of anthropogenic and natural disturbances to support EIA requirements. We applied the GCBM to approximately 1.3 million ha of upland forest in a pilot study area of the oil sands region of Alberta that has experienced a large number of anthropogenic (forestry, energy sector) and natural (wildfire, insect) disturbances. RESULTS: Over the 28 years, 25% of the pilot study area was disturbed. Increasing disturbance emissions, combined with declining net primary productivity and reductions in forest area, changed the study area from a net C sink to a net C source. Forest C stocks changed from 332.2 Mt to 327.5 Mt, declining by 4.7 Mt at an average rate of 0.128 tC ha-1 yr-1. The largest cumulative areas of disturbance were caused by wildfire (139,000 ha), followed by the energy sector (110,000 ha), insects (33,000 ha) and harvesting (31,000 ha) but the largest cumulative disturbance emissions were caused by the energy sector (9.5 Mt C), followed by wildfire (5.5 Mt C), and then harvesting (1.3 Mt C). CONCLUSION: An existing forest C model was used successfully to provide a rigorous regional cumulative assessment of anthropogenic and natural disturbances on forest C, which meets requirements of EIAs in Canada. The assessment showed the relative importance of disturbances on C emissions in the pilot study area, but their relative importance is expected to change in other parts of the oil sands region because of its diversity in disturbance types, patterns and intensity. Future assessments should include peatland C stocks and fluxes, which could be addressed by using the Canadian Model for Peatlands.

Climate change mitigation in British Columbia's forest sector: GHG reductions, costs, and environmental impacts.

BACKGROUND: The potential contributions from forest-based greenhouse gas (GHG) mitigation actions need to be quantified to develop pathways towards net negative emissions. Here we present results from a comparative analysis that examined mitigation options for British Columbia's forest sector. Mitigation scenarios were evaluated using a systems perspective that takes into account the changes in emissions and removals in forest ecosystems, in harvested wood product (HWP) carbon stocks, and in other sectors where wood products substitute for emission-intensive materials and fossil fuels. All mitigation activities were assessed relative to a forward-looking 'business as usual' baseline for three implementation levels. In addition to quantifying net GHG emission reductions, we assessed economic, and socio-economic impacts as well as other environmental indicators relating to forest species, age class, deadwood availability and future timber supply. We further considered risks of reversal for land-based scenarios, by assessing impacts of increasing future wildfires on stands that were not harvested. RESULTS: Our spatially explicit analyses of forest sector mitigation options demonstrated a cost-effective portfolio of regionally differentiated scenarios that directed more of the harvested wood to longer-lived wood products, stopped burning of harvest residues and instead produced bioenergy to displace fossil fuel burning, and reduced harvest levels in regions with low disturbance rates. Domestically, net GHG emissions were reduced by an average of -9 MtCO2e year-1 over 2020-2050 for a portfolio of mitigation activities at a default implementation level, with about 85% of the GHG emission reductions achieved below a cost of $50/tCO2e. Normalizing the net GHG reduction by changes in harvested wood levels permitted comparisons of the scenarios with different ambition levels, and showed that a 1 MtCO2 increase in cumulative harvested stemwood results in a 1 MtCO2e reduction in cumulative emissions, relative to the baseline, for the Higher Recovery scenario in 2070. CONCLUSIONS: The analyses conducted in this study contribute to the global understanding of forest sector mitigation options by providing an integrated framework to synthesize the methods, assumptions, datasets and models needed to quantify mitigation activities using a systems approach. An understanding of economically feasible and socio-economically attractive mitigation scenarios along with trade offs for environmental indicators relating to species composition and age, helps decision makers with long-term planning for land sector contributions to GHG emission reduction efforts, and provides valuable information for stakeholder consultations.

Geochemistry and Microtextures of Vein Calcites Pervading the Izu-Bonin Forearc and Rear Arc Crust: New Insights From IODP Expeditions 352 and 351.

International Ocean Discovery Program Expeditions 352 and 351 drilled into the Western Pacific Izu-Bonin forearc and rear arc. The drill cores revealed that the forearc is composed of forearc basalts (FAB) and boninites and the rear arc consists of FAB-like rocks. These rocks are pervaded by calcite veins. Blocky vein microtextures enclosing host rock fragments dominate in all locations and suggest hydrofracturing and advective fluid flow. Significant diffusion-fed and crystallization pressure-driven antitaxial veining is restricted to the rear arc. The lack of faults and presence of an Eocene sedimentary cover in the rear arc facilitated antitaxial veining. Rare earth element and isotopic (δ18O, δ13C, 87Sr/86Sr, and Δ47) tracers indicate varying parental fluid compositions ranging from pristine to variably modified seawater. The most pristine seawater signatures are recorded by FAB-hosted low-T (<30 °C) vein calcites. Their 87Sr/86Sr ratios intersect the 87Sr/86Sr seawater curve at ~35-33 and ~22 Ma. These intersections are interpreted as precipitation ages, which concur with Pacific slab rollback. Boninite-hosted low-T (<30 °C) vein calcites precipitated from seawater that was modified by fluid-rock interactions. Mixing calculations yield a mixture of >95% seawater and <5% basaltic 87Sr/86Sr. In the rear arc, low-T rock alteration lowered the circulating seawater in δ18O and 87Sr/86Sr. Thus, vein calcites precipitated from modified seawater with up to 20-30% basaltic 87Sr/86Sr at temperatures up to 74 ± 12 °C. These results show how the local geology and vein growth dynamics affect microtextures and geochemical compositions of vein precipitates.

Postmagmatic Tectonic Evolution of the Outer Izu-Bonin Forearc Revealed by Sediment Basin Structure and Vein Microstructure Analysis: Implications for a 15 Ma Hiatus Between Pacific Plate Subduction Initiation and Forearc Extension.

International Ocean Discovery Program Expedition 352 recovered sedimentary-volcaniclastic successions and extensional structures (faults and extensional veins) that allow the reconstruction of the Izu-Bonin forearc tectonic evolution using a combination of shipboard core data, seismic reflection images, and calcite vein microstructure analysis. The oldest recorded biostratigraphic ages within fault-bounded sedimentary basins (Late Eocene to Early Oligocene) imply a ~15 Ma hiatus between the formation of the igneous basement (52 to 50 Ma) and the onset of sedimentation. At the upslope sites (U1439 and U1442) extension led to the formation of asymmetric basins reflecting regional stretch of ~16-19% at strain rates of ~1.58 × 10-16 to 4.62 × 10-16 s-1. Downslope Site U1440 (closer to the trench) is characterized by a symmetric graben bounded by conjugate normal faults reflecting regional stretch of ~55% at strain rates of 4.40 × 10-16 to 1.43 × 10-15 s-1. Mean differential stresses are in the range of ~70-90 MPa. We infer that upper plate extension was triggered by incipient Pacific Plate rollback ~15 Ma after subduction initiation. Extension was accommodated by normal faulting with syntectonic sedimentation during Late Eocene to Early Oligocene times. Backarc extension was assisted by magmatism with related Shikoku and Parece-Vela Basin spreading at ~25 Ma, so that parts of the arc and rear arc, and the West Philippine backarc Basin were dismembered from the forearc. This was followed by slow-rift to postrift sedimentation during the transition from forearc to arc rifting to spreading within the Shikoku-Parece-Vela Basin system.

Geochemistry of Vein Calcites Hosted in the Troodos Pillow Lavas and Their Implications for the Timing and Physicochemical Environment of Fracturing, Fluid Circulation, and Vein Mineral Growth.

Calcite veins hosted in pillow lavas of the Late Cretaceous Troodos suprasubduction zone ophiolite provide insights into the timing and physicochemical environment of postmagmatic fracturing and fluid circulation through oceanic crust. This study presents rare earth element and yttrium (REE+Y) concentrations, δ13C, δ18O, 87Sr/86Sr, and clumped isotopic (Δ47) compositions of vein calcites in order to investigate their fluid sources, formation temperatures, and precipitation ages. These geochemical data are combined with microtextural analyses. Intersections of 87Sr/86Sr ratios of vein calcites with the Sr isotope seawater curve suggest two distinct calcite veining phases. Major calcite veining within an interval of ~10 Myr after crust formation is characterized by microtextures that point to extensional fracturing related to crack and sealing, host rock brecciation, and advective fluid flow. These vein calcites show REE+Y characteristics, 87Sr/86Sr ratios, and clumped isotopic compositions indicative of precipitation from seawater at <50 °C. Extended fluid residence times intensified fluid-rock interactions and lowered Y/Ho ratios of some blocky vein calcites, whereas crack and sealing resulted in pristine seawater signatures. Low 87Sr/86Sr ratios of localized high-temperature blocky vein calcites point to the involvement of hydrothermal fluids. These calcites show Mn-controlled oscillatory growth zonations that probably developed in a closed system out of equilibrium. Later calcite veining (<75 Ma) may have coincided with rotation and/or uplift of the Troodos ophiolite. Microtextures of these vein calcites indicate fluid diffusion and fracture-independent crystallization pressure-driven veining. Their variably modified seawater signatures resulted from diffusion-related fluid interaction with hydrothermal sediments.

Climate change mitigation in Canada's forest sector: a spatially explicit case study for two regions.

BACKGROUND: We determine the potential of forests and the forest sector to mitigate greenhouse gas (GHG) emissions by changes in management practices and wood use for two regions within Canada's managed forest from 2018 to 2050. Our modeling frameworks include the Carbon Budget Model of the Canadian Forest Sector, a framework for harvested wood products that estimates emissions based on product half-life decay times, and an account of marginal emission substitution benefits from the changes in use of wood products and bioenergy. Using a spatially explicit forest inventory with 16 ha pixels, we examine mitigation scenarios relating to forest management and wood use: increased harvesting efficiency; residue management for bioenergy; reduced harvest; reduced slashburning, and more longer-lived wood products. The primary reason for the spatially explicit approach at this coarse resolution was to estimate transportation distances associated with delivering harvest residues for heat and/or electricity production for local communities. RESULTS: Results demonstrated large differences among alternative scenarios, and from alternative assumptions about substitution benefits for fossil fuel-based energy and products which changed scenario rankings. Combining forest management activities with a wood-use scenario that generated more longer-lived products had the highest mitigation potential. CONCLUSIONS: The use of harvest residues to meet local energy demands in place of burning fossil fuels was found to be an effective scenario to reduce GHG emissions, along with scenarios that increased the utilization level for harvest, and increased the longevity of wood products. Substitution benefits from avoiding fossil fuels or emissions-intensive products were dependent on local circumstances for energy demand and fuel mix, and the assumed wood use for products. As projected future demand for biomass use in national GHG mitigation strategies could exceed sustainable biomass supply, analyses such as this can help identify biomass sources that achieve the greatest mitigation benefits.

Spatially-integrated estimates of net ecosystem exchange and methane fluxes from Canadian peatlands.

BACKGROUND: Peatlands are an important component of Canada's landscape, however there is little information on their national-scale net emissions of carbon dioxide [Net Ecosystem Exchange (NEE)] and methane (CH4). This study compiled results for peatland NEE and CH4 emissions from chamber and eddy covariance studies across Canada. The data were summarized by bog, poor fen and rich-intermediate fen categories for the seven major peatland containing terrestrial ecozones (Atlantic Maritime, Mixedwood Plains, Boreal Shield, Boreal Plains, Hudson Plains, Taiga Shield, Taiga Plains) that comprise > 96% of all peatlands nationally. Reports of multiple years of data from a single site were averaged and different microforms (e.g., hummock or hollow) within these peatland types were kept separate. A new peatlands map was created from forest composition and structure information that distinguishes bog from rich and poor fen. National Forest Inventory k-NN forest structure maps, bioclimatic variables (mean diurnal range and seasonality of temperatures) and ground surface slope were used to construct the new map. The Earth Observation for Sustainable Development map of wetlands was used to identify open peatlands with minor tree cover. RESULTS: The new map was combined with averages of observed NEE and CH4 emissions to estimate a growing season integrated NEE (± SE) at - 108.8 (± 41.3) Mt CO2 season-1 and CH4 emission at 4.1 (± 1.5) Mt CH4 season-1 for the seven ecozones. Converting CH4 to CO2 equivalent (CO2e; Global Warming Potential of 25 over 100 years) resulted in a total net sink of - 7.0 (± 77.6) Mt CO2e season-1 for Canada. Boreal Plains peatlands contributed most to the NEE sink due to high CO2 uptake rates and large peatland areas, while Boreal Shield peatlands contributed most to CH4 emissions due to moderate emission rates and large peatland areas. Assuming a winter CO2 emission of 0.9 g CO2 m-2 day-1 creates an annual CO2 source (24.2 Mt CO2 year-1) and assuming a winter CH4 emission of 7 mg CH4 m-2 day-1 inflates the total net source to 151.8 Mt CO2e year-1. CONCLUSIONS: This analysis improves upon previous basic, aspatial estimates and discusses the potential sources of the high uncertainty in spatially integrated fluxes, indicating a need for continued monitoring and refined maps of peatland distribution for national carbon and greenhouse gas flux estimation.

Estimation of snag carbon transfer rates by ecozone and lead species for forests in Canada.

Standing dead trees (snags) and downed woody debris contribute substantially to the carbon (C) budget of Canada's forest. Accurate parameterization of the C transfer rates (CTRs) from snags to downed woody debris is important for forest C dynamics models such as the Carbon Budget Model of the Canadian Forest Sector (CBM-CFS3), but CTRs are rarely measured or reported in the literature. Therefore, forest C models generally use snag fall rates (FRs) available in the literature, as a proxy for CTRs. However, FRs are based on stem counts while CTRs refer to mass transfers. Stem mass and stem number are not linearly related, with small diameter trees representing disproportionately lower C mass transfers. Therefore this proxy, while convenient, may bias C transfer from standing dead to downed woody material. Here, we combined tree data from 10802 sample plots and previously published species-specific individual-tree relationships between tree diameter (diameter at breast height, dbh) and fall rate to derive stand-level estimates of CTRs for the CBM-CFS3. We estimated CTRs and FRs and used the FR values to validate this approach by comparing them with standardized FR values compiled from the literature. FRs generally differed from CTRs. The overall CTR (4.78% +/- 0.02% per year, mean +/- SE) was significantly smaller than the overall FR (5.40% +/- 0.02% per year; mean +/- SE). Both the difference between FR and CTR (FR - CTR) and the CTR itself varied by ecozone, with ecozone means for CTR ranging from 3.94% per year to 10.02% per year. This variation was explained, in part, by heterogeneity in species composition, size (dbh distribution), structure, and age of the stands. The overall mean CTR estimated for the Snag_Stemwood (4.78% per year) and the Snag_Branches (11.95% per year) pools of the CBM-CFS3 were approximately 50% and 20% higher than the current default rates used in the CBM-CFS3 of 3.2% and 10.0%, respectively. Our results demonstrate that using CTRs to estimate the annual C transfer from standing dead trees to downed woody biomass will yield more accurate estimates of C fluxes than using a FR proxy, and this accuracy could be further improved by accounting for differences in ecozone, stand component (hardwood or softwood), or lead species.

Assessment of boreal forest historical C dynamics in the Yukon River Basin: relative roles of warming and fire regime change.

Carbon (C) dynamics of boreal forest ecosystems have substantial implications for efforts to mitigate the rise of atmospheric CO2 and may be substantially influenced by warming and changing wildfire regimes. In this study we applied a large-scale ecosystem model that included dynamics of organic soil horizons and soil organic matter characteristics of multiple pools to assess forest C stock changes of the Yukon River Basin (YRB) in Alaska, USA, and Canada from 1960 through 2006, a period characterized by substantial climate warming and increases in wildfire. The model was calibrated for major forests with data from long-term research sites and evaluated using a forest inventory database. The regional assessment indicates that forest vegetation C storage increased by 46 Tg C, but that total soil C storage did not change appreciably during this period. However, further analysis suggests that C has been continuously lost from the mineral soil horizon since warming began in the 1970s, but has increased in the amorphous organic soil horizon. Based on a factorial experiment, soil C stocks would have increased by 158 Tg C if the YRB had not undergone warming and changes in fire regime. The analysis also identified that warming and changes in fire regime were approximately equivalent in their effects on soil C storage, and interactions between these two suggests that the loss of organic horizon thickness associated with increases in wildfire made deeper soil C stocks more vulnerable to loss via decomposition. Subbasin analyses indicate that C stock changes were primarily sensitive to the fraction of burned forest area within each subbasin and that boreal forest ecosystems in the YRB are currently transitioning from being sinks to sources at -0.7% annual area burned. We conclude that it is important for international mitigation efforts focused on controlling atmospheric CO2 to consider how climate warming and changes in fire regime may concurrently affect the CO2 sink strength of boreal forests. It is also important for large-scale biogeochemical and earth system models to include organic soil dynamics in applications to assess regional C dynamics of boreal forests responding to warming and changes in fire regime.

Monitoring carbon stocks in the tropics and the remote sensing operational limitations: from local to regional projects.

Current remote sensing technologies are effective tools for contributing to the estimation of terrestrial carbon stocks and carbon stock changes. This paper provides an overview of information requirements, sensor capabilities and limitations, and analysis approaches for the use of remotely sensed data in the generation of tropical carbon sequestration monitoring systems. While it is evident that remotely sensed data have tremendous utility for monitoring carbon stock changes, it is important to be aware of their limitations. Three critical limitations are: (1) the definition of methods and algorithms to accurately estimate forest age, (2) the provision of techniques that can yield accurate estimation of deforestation rates in both tropical dry and wet forest environments, and (3) the strong need to develop new approaches to link biophysical variables (e.g., leaf area index) to spectral reflectance to support spatially distributed carbon sequestration models. The validity of final estimates of carbon and carbon stock changes rests on complex issues at several levels, from the data themselves, to the analysis, interpretation, and validation of the data. Consideration of these issues, as well as the need for sound project planning and development within budget constraints, will be important in the development of carbon stock monitoring programs in the tropics.

[Colonic perforation after extracorporeal shock wave lithotripsy]. / Kolonperforation nach extrakorporaler Stosswellenlithotripsie.

HISTORY AND CLINICAL FINDINGS: A 40-year-old man had undergone extracorporeal shock wave lithotripsy (ESWL) due to left sided urinary lithiasis. 20 hours later he presented with left lower quadrant abdominal pain. INVESTIGATIONS: Ultrasound examination revealed free intraabdominal air and free perisplenic fluid. An injury of the left kidney could be excluded. TREATMENT AND COURSE: Due to increasing abdominal pain a laparoscopy was performed, revealing a faecal peritonitis. Since no perforation could be detected laroscopically, a laparotomy was performed, demonstrating a perforation of the descending colon. The perforation was oversewn, a defunctioning colostomy was not performed. Postoperatively the patient had an uncomplicated hospital stay and was discharged home on postoperative day 8. CONCLUSION: ESWL is considered a safe method to treat urinary lithiasis with a low complication rate. Nevertheless serious potentially life-threatening pararenal complications can occur. Due to the increasing number of outpatient procedures, a careful clinical and ultrasound monitoring of the patient with early recognition and interdisciplinary management of complications is necessary after each ESWL therapy.

Mountain pine beetle and forest carbon feedback to climate change.

The mountain pine beetle (Dendroctonus ponderosae Hopkins, Coleoptera: Curculionidae, Scolytinae) is a native insect of the pine forests of western North America, and its populations periodically erupt into large-scale outbreaks. During outbreaks, the resulting widespread tree mortality reduces forest carbon uptake and increases future emissions from the decay of killed trees. The impacts of insects on forest carbon dynamics, however, are generally ignored in large-scale modelling analyses. The current outbreak in British Columbia, Canada, is an order of magnitude larger in area and severity than all previous recorded outbreaks. Here we estimate that the cumulative impact of the beetle outbreak in the affected region during 2000-2020 will be 270 megatonnes (Mt) carbon (or 36 g carbon m(-2) yr(-1) on average over 374,000 km2 of forest). This impact converted the forest from a small net carbon sink to a large net carbon source both during and immediately after the outbreak. In the worst year, the impacts resulting from the beetle outbreak in British Columbia were equivalent to approximately 75% of the average annual direct forest fire emissions from all of Canada during 1959-1999. The resulting reduction in net primary production was of similar magnitude to increases observed during the 1980s and 1990s as a result of global change. Climate change has contributed to the unprecedented extent and severity of this outbreak. Insect outbreaks such as this represent an important mechanism by which climate change may undermine the ability of northern forests to take up and store atmospheric carbon, and such impacts should be accounted for in large-scale modelling analyses.

[Breast carcinoma in routine surgery. Challenges and reality]. / Das Mammakarzinom im chirurgischen Alltag. Forderungen und Realität.

This is a brief comment on results in the common surgical treatment of breast cancer. Based on guiding-lines given by the surgical congress 1985 the decentralized treatment routine as it is common today has been analysed and its results have been applied to our regional structures. Under the premises of standardized diagnosis as well as surgical and postoperative treatment the decentralized treatment of breast cancer is still supported and considered useful. Main critical point in the whole therapy concept is the postoperative treatment, especially the adjuvant therapy. Looking for future solutions it seems to be more effective to reduce the amount of surgical facilities for the benefit of profiling the remaining ones. This could be applicable for the treatment of other diseases as well. The improvements that would result from this conceptional concentration would be profitable as well for the patients as for the surgeons.

The carbon budget of Canadian forests: a sensitivity analysis of changes in disturbance regimes, growth rates, and decomposition rates.

Ecosystem responses to climate changes will affect the exchange of carbon (C) with the atmosphere, thus providing feedback for future climate response. We have developed a C budget model of Canadian forests and forest sector activities and used sensitivity analysis runs with changes in productivity, decomposition, and disturbance regimes to assess the sensitivity of the Canadian forest sector C budget over the next century. The model operates on data derived from Canada's National Forest Biomass Inventory, from the Oak Ridge National Laboratory global soil C data base, and from Canadian data bases that document areas annually disturbed by fire, insects, and harvesting. It simulates the dynamics of biomass and soil C pools (including detritus and coarse woody debris) as they are affected by growth, decomposition, and disturbances. For the reference run of the model, we assumed unchanging climate and disturbance regimes. Under these conditions, total ecosystem C increased by 2 Gt C (2.3%) over the 100-year simulation period. In the sensitivity analysis, we explored the effects of changes in the area annually disturbed by fire and insect-induced stand mortality (-60 to +300%), growth rates (-10 to +20%), decomposition rates (-10 to +25%), and combined changes in growth and decomposition rates. In every model run, the change of total ecosystem C relative to the reference run was less than 10%. Combined changes to growth and decomposition rates yielded very small deviations from the results of the reference run (-0.8 to +1.2%). Because disturbance regime changes affect forest age-class structure as well as forest dynamics, they are expected to affect C budgets strongly. Total ecosystem C, however, is slightly more sensitive to changes in growth and decomposition parameters than to changes in disturbance regimes. Although the sensitivity analysis results suggest that C budgets are little affected by the range of parameter changes implemented here, we must emphasize that our sensitivity analyses do not account for potentially important processes, such as regeneration failure or the shifts in forest distribution.

[Treatment of Monteggia fracture in children]. / Die Behandlung der Monteggia-Fraktur beim Kind.

Described in this paper is a therapeutic concept by which to cope with Monteggia's fracture in childhood. It is based on experience obtained from 72 cases with injuries of that kind and their evaluation in a group study. Therapeutic approach to the individual case was determined by the following criteria: age of infant, localisation and shape of ulnar fracture, reducibility of capitulum radii, and accompanying injuries requiring treatment on the same arm. The need for surgical stabilisation of ulnar fracture was found to increase along with growing age of the affected child. High-stability anatomic reduction of the ulnar fracture proved to be a prerequisite for safe stabilisation of the radial capitulum. Close reduction has proved to be sufficient in many instances. Open reduction and internal fixation were found to be necessary in cases in which an ulnar fracture was irreducible or instable and/or a radial head was not reducible. Minimal osteosynthesis and plaster cast is considered to be an optional therapy for younger children, whereas ulnar stabilisation by means of plates is preferred for children in somewhat advanced age of childhood. The radial head may be fixed by trans-articular Kirschner's wire (WITT) or primary reconstruction of the annular ligament, using a strip of biceps or triceps tendon, or adaptation around the collum radii and ulna of the proximal radio-ulnar joint by means of a sling of Dexon or Vicryl suture.

High levels of tryptamine accumulation in transgenic tobacco expressing tryptophan decarboxylase.

A full-length complementary DNA clone encoding tryptophan decarboxylase (TDC; EC 4.1.1.28) from Catharanthus roseus (De Luca V, Marineau C, Brisson N [1989] Proc Natl Acad Sci USA 86: 2582-2586) driven by the CaMV 35S promoter was introduced into tobacco (Nicotiana tabacum) to direct the synthesis of the protoalkaloid tryptamine from endogenous tryptophan. Young, fully expanded leaves of CaMV 35S-TDC transformed plants had from four to 45 times greater TDC activity than did controls. Tryptamine accumulated in transgenic plants to levels that were directly proportional to their TDC specific activity. Despite their increased tryptamine content, the growth and development of the CaMV 35S-TDC plants appeared normal with no significant differences in indole-3-acetic acid levels between high tryptamine and control plants. Plants with the highest TDC activity contained more than 1 milligram of tryptamine per gram fresh weight, a 260-fold increase over controls.

Purification and characterization of acetylcoenzyme A: deacetylvindoline 4-O-acetyltransferase from Catharanthus roseus.

The enzyme acetylcoenzyme A:deacetylvindoline 4-O-acetyltransferase (EC 2.3.1.-) (DAT), which catalyzes the final step in vindoline biosynthesis in Catharanthus roseus, was purified 3300-fold using ammonium sulfate precipitation followed by gel filtration, anion exchange, hydroxyapatite, and affinity chromatographies. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of the purified DAT showed the presence of two major proteins having Mr values of 33,000 and 21,000, whereas native PAGE showed three protein bands, and isoelectric focusing-PAGE one diffuse protein band (pI = 4.7-5.3) plus two minor protein bands (pI = 5.7 and 6.1). Purified DAT possessed Km values of 6.5 microM and 1.3 microM for acetylcoenzyme A and deacetylvindoline, respectively, and Vmax values of 12.6 pkat/microgram protein (acetylcoenzyme A) and 10.1 pkat/micrograms protein (deacetylvindoline). Inhibition of DAT by tabersonine, coenzyme A, and cations (K+, Mg2+, and Mn2+) was observed, while the pH optimum of this enzyme was determined to be 7.5 to 9.