Trends in appropriateness of end-of-life care in people with cancer, COPD or with dementia measured with population-level quality indicators.

INTRODUCTION: Measuring changes in the appropriateness of end-of-life care provided to patients with advanced illness such as cancer, COPD or dementia can help governments and practitioners improve service delivery and quality of life. However, an assessment of a possible shift in appropriateness of end-of-life care across the population is lacking. AIM: Measuring quality indicators with routinely collected population-level data, this study aims to evaluate the appropriateness of end-of-life care for people with cancer, COPD or dementia in Belgium. DESIGN: A population-level decedent cohort study, using data from eight population-level databases, including death certificate and health claims data. We measured validated sets of quality indicators for appropriateness of end-of-life care. SETTING/PARTICIPANTS: All people who died from cancer or COPD or with dementia between 1st January 2010 and 1st January 2016 in Belgium. RESULTS: We identified three main trends over time across the three disease groups of increasing use of: family physicians in the last 30 days of life (+21.7% in cancer, +33.7% in COPD and +89.4% in dementia); specialist palliative care in the last 14 days of life (+4.6% in cancer, +36.9% in COPD, +17.8% in dementia); and emergency department in the last 30 days of life (+7.0% in cancer, +4.4% in COPD and +8.2% in dementia). CONCLUSIONS: Although we found an increase of both specialized palliative care and generalist palliative care use, we also found an increase in potentially inappropriate care, including ED and ICU admissions. To increase the quality of end-of-life care, both timely initiating (generalist and specialist) palliative care and avoiding potentially inappropriate care transitions, treatments and medications need to be quality performance targets.

Appropriateness of End-of-Life Care in People Dying With Dementia: Applying Quality Indicators on Linked Administrative Databases.

OBJECTIVES: Dementia is a progressive incurable life-limiting illness. Previous research suggests end-of-life care for people with dementia should have a symptomatic focus with an effort to avoid burdensome interventions that would not improve quality of life. This study aims to assess the appropriateness of end-of-life care in people who died with dementia in Belgium and to establish relative performance standards by measuring validated population-level quality indicators. DESIGN: We conducted a retrospective observational study. SETTING AND PARTICIPANTS: We included all persons deceased with dementia in 2015 in Belgium. Data from 8 administratively collected population-level databases was linked. MEASURES: We used a validated set of 28 quality indicators for end-of-life dementia care. We compared quality indicator scores across 14 healthcare regions to establish relative benchmarks. RESULTS: In Belgium in 2015, 10,629 people died with dementia. For indicators of appropriate end-of-life care, people who died with dementia had on average 1.83 contacts with their family physician in the last week before death, whereas 68.4% died at home or in their nursing home of residence. For indicators of inappropriate end-of-life care, 32.4% were admitted to the hospital and 36.3% underwent diagnostic testing in the last 30 days before death, whereas 25.1% died in the hospital. In the last 30 days, emergency department admission varied between 19% and 31%, dispensing of gastric protectors between 18% and 42%, and antihypertensives between 40% and 53% between healthcare regions, with at least 25% of health regions below 46%. CONCLUSIONS AND IMPLICATIONS: Our study found indications of appropriate as well as inappropriate end-of-life care in people with dementia, including high rates of family physician contact, as well as high percentages of diagnostic testing, and emergency department and hospital admissions. We also found high risk-adjusted variation for multiple quality indicators, indicating opportunity for quality improvement in end-of-life dementia care.

Who finds the road to palliative home care support? A nationwide analysis on the use of supportive measures for palliative home care using linked administrative databases.

BACKGROUND: Many countries developed supportive measures for palliative home care, such as financial incentives or multidisciplinary palliative home care teams. For policy makers, it is important to evaluate the use of these national palliative home care supportive measures on a population level. METHODS AND FINDINGS: Using routinely-collected data on all deaths in Belgium in 2012 (n = 107,847) we measured the use of four statutory supportive measures, specifically intended for patients who have obtained the legal palliative status, and three non-statutory supportive measures. Factors associated with uptake were analysed using multivariable logistic regression. Of all deaths of adult home-dwelling persons in Belgium (n = 87,007), 17.9 percent used at least one statutory supportive measure and 51.5 percent used at least one non-statutory supportive measure. In those who died of an illness indicative of palliative care needs 33.1 percent used at least one statutory supportive measure and 62.2 percent used at least one non-statutory supportive measure. Younger people and persons dying from cancer were more likely to use a statutory policy measure. Older people and persons dying from COPD were most likely to use a non-statutory policy measure. Women, non-single people, and those living in less urbanised areas were most likely to use any supportive measure. CONCLUSIONS: Statutory supportive measures for palliative home care are underused, even in a subpopulation of persons with potential palliative care needs. Policy makers should stimulate an equitable uptake, and reducing the observed inequalities is an important focus for health care policy.

Appropriateness of End-of-Life Care in People Dying From COPD. Applying Quality Indicators on Linked Administrative Databases.

CONTEXT: Large-scale evaluations of the quality of end-of-life care in people with chronic obstructive pulmonary disease (COPD) are lacking. OBJECTIVES: By means of a validated set of quality indicators (QIs), this study aimed to 1) assess appropriateness of end-of-life care in people dying from COPD; 2) examine variation between care regions; 3) establish performance standards. METHODS: We conducted a retrospective observational study of all deaths from COPD (ICD-10 codes J41-J44) in 2012 in Belgium, using data from administrative population-level databases. QI scores were risk-adjusted for comparison between care regions. RESULTS: A total of 4231 people died from COPD. During the last 30 days of life, 60% was admitted to hospital and 11.8% received specialized palliative care. Large regional variation was found in specialized palliative care use (4.0%-32.0%) and diagnostic testing in the last 30 days of life (44.0%-69.7%). Based on best performing quartile scores, relative standards were set (e.g., ≤54.9% for diagnostic testing). CONCLUSION: Our study found indications of inappropriate end-of-life care in people with COPD, such as high percentages of diagnostic testing and hospital admissions and low proportions receiving specialized palliative care. Risk-adjusted variation between regions was high for several QIs, indicating the usefulness of relative performance standards to improve quality of end-of-life COPD care.

The implementation of academic detailing and its effectiveness on appropriate prescribing of pain relief medication: a real-world cluster randomized trial in Belgian general practices.

BACKGROUND: In Belgium, the debate about the effect of the national academic detailing service (ADS) on prescribing quality in general practice is ongoing. In order to evaluate both the implementation strategies of the ADS and its effectiveness on appropriate prescribing of pain relief medication, we conducted a real-world cluster randomized controlled trial (cRCT). METHODS: In a pragmatic cRCT, all Belgian general practices previously visited by Farmaka were assessed for eligibility and randomized. Only practices randomized to the intervention group were invited for an academic detailing visit on appropriate prescribing of pain relief medication. GPs were unaware of the study, ensuring the production of real-world evidence but were given the option to opt out from the analysis. An objective outcome assessment was obtained using routinely collected reimbursement data. Primary outcomes were the proportion of patients reimbursed for an analgesic or NSAID, the defined daily dose of paracetamol per patient per month, the proportion of patients reimbursed for a recommended NSAID among those reimbursed for any NSAID and the proportion of patients reimbursed for both an NSAID and a proton pump inhibitor among those reimbursed for an NSAID. The impact of practice, GP and academic detailer characteristics were also assessed. RESULTS: Three thousand five hundred twenty-nine general practices (4530 GPs) were eligible and randomized. One thousand six hundred ninety-eight practices (2171 GPs) in the intervention group and one thousand seven hundred three (2163 GPs) in the control group were included in the analysis. The intervention had a significant impact on the proportion of patients reimbursed for a recommended NSAID among those reimbursed for any NSAID (increase in odds (95% CI): 19% (10-29%)). A clear impact on other outcomes could not be detected. Additionally, we showed that the characteristics of the academic detailers might impact the effectiveness of the visit. CONCLUSIONS: National implementation of academic detailing in Belgian general practices provided by Farmaka significantly improved the proportion of recommended NSAIDs prescribed by GPs, but not other outcomes related to appropriate prescribing of pain relief medication. TRIAL REGISTRATION: NCT01761864 . Registered 2 January 2013.

Applying Quality Indicators For Administrative Databases To Evaluate End-Of-Life Care For Cancer Patients In Belgium.

End-of-life cancer care has been criticized as frequently inappropriate and aggressive. Providing appropriate care to people with cancer is a public health priority. Quality indicators are considered a valid way to evaluate the appropriateness of end-of-life cancer care within a health care system. We conducted a population-level retrospective observational study of all cancer decedents in Belgium in 2012 to assess end-of-life care and risk factors for exposure to care. We linked eight full-population databases on health care use, cancer diagnoses, and demographic and socioeconomic variables. We used analysis of variance to examine factors associated with exposure to appropriate or inappropriate end-of-life cancer care. Of the 26,464 people in Belgium who died from cancer in 2012, 47 percent received specialist palliative care, and 30 percent died at home. In the last thirty days of life, 17 percent received chemotherapy, and 66 percent received diagnostic testing. For 17 percent, palliative care was initiated only in the last fourteen days of life. Our results suggest a need to focus policy on reducing aggressive and inappropriate care at the end of life and an opportunity to increase the proportion of people who receive specialist palliative care and die at home.

Using linked administrative and disease-specific databases to study end-of-life care on a population level.

BACKGROUND: The use of full-population databases is under-explored to study the use, quality and costs of end-of-life care. Using the case of Belgium, we explored: (1) which full-population databases provide valid information about end-of-life care, (2) what procedures are there to use these databases, and (3) what is needed to integrate separate databases. METHODS: Technical and privacy-related aspects of linking and accessing Belgian administrative databases and disease registries were assessed in cooperation with the database administrators and privacy commission bodies. For all relevant databases, we followed procedures in cooperation with database administrators to link the databases and to access the data. RESULTS: We identified several databases as fitting for end-of-life care research in Belgium: the InterMutualistic Agency's national registry of health care claims data, the Belgian Cancer Registry including data on incidence of cancer, and databases administrated by Statistics Belgium including data from the death certificate database, the socio-economic survey and fiscal data. To obtain access to the data, approval was required from all database administrators, supervisory bodies and two separate national privacy bodies. Two Trusted Third Parties linked the databases via a deterministic matching procedure using multiple encrypted social security numbers. CONCLUSION: In this article we describe how various routinely collected population-level databases and disease registries can be accessed and linked to study patterns in the use, quality and costs of end-of-life care in the full population and in specific diagnostic groups.

Implementation of a Care Pathway for Primary Palliative Care in 5 research clusters in Belgium: quasi-experimental study protocol and innovations in data collection (pro-SPINOZA).

BACKGROUND: Starting with early identification of palliative care patients by general practitioners (GPs), the Care Pathway for Primary Palliative Care (CPPPC) is believed to help primary health care workers to deliver patient- and family-centered care in the last year of life. The care pathway has been pilot-tested, and will now be implemented in 5 Belgian regions: 2 Dutch-speaking regions, 2 French-speaking regions and the bilingual capital region of Brussels. The overall aim of the CPPPC is to provide better quality of primary palliative care, and in the end to reduce the hospital death rate. The aim of this article is to describe the quantitative design and innovative data collection strategy used in the evaluation of this complex intervention. METHODS/DESIGN: A quasi-experimental stepped wedge cluster design is set up with the 5 regions being 5 non-randomized clusters. The primary outcome is reduced hospital death rate per GPs' patient population. Secondary outcomes are increased death at home and health care consumption patterns suggesting high quality palliative care. Per research cluster, GPs will be recruited via convenience sampling. These GPs -volunteering to be involved will recruit people with reduced life expectancy and their informal care givers. Health care consumption data in the last year of life, available for all deceased people having lived in the research clusters in the study period, will be used for comparison between patient populations of participating GPs and patient populations of non-participating GPs. Description of baseline characteristics of participating GPs and patients and monitoring of the level of involvement by GPs, patients and informal care givers will happen through regular, privacy-secured web-surveys. Web-survey data and health consumption data are linked in a secure way, respecting Belgian privacy laws. DISCUSSION: To evaluate this complex intervention, a quasi-experimental stepped wedge cluster design has been set up. Context characteristics and involvement level of participants are important parameters in evaluating complex interventions. It is possible to securely link survey data with health consumption data. By appealing to IT solutions we hope to be able to partly reduce respondent burden, a known problem in palliative care research. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02266069.

Appropriate international measures for outpatient antibiotic prescribing and consumption: recommendations from a national data comparison of different measures.

OBJECTIVES: Many European countries have engaged in awareness campaigns to decrease outpatient antibiotic use and several measures have been proposed, e.g. the number of defined daily doses (DDDs) or packages per 1000 inhabitants per day, producing conflicting findings. Therefore, we set out to explore what measure is most appropriate. METHODS: Outpatient data on each dispensed and reimbursed medicinal package in Belgium between 2002 and 2009 were aggregated at the level of the active substance in accordance with the Anatomical Therapeutic Chemical classification and expressed as the numbers of DDDs (WHO, version 2010), packages, treatments and insured individuals per 1000 inhabitants, insured individuals and patient contacts, per day, and in July-June years. Using these measures, time trends of outpatient antibiotic use were compared and explored in detail. RESULTS: Expressed per 1000 inhabitants per day, outpatient antibiotic use increased between 2002-03 and 2008-09 in DDDs, whereas in packages, treatments and insured individuals it decreased. The same was true for use expressed per 1000 insured individuals or when allowing for the decreasing number of patient contacts. Increasing numbers of DDDs per package (more items per package and higher doses per unit for amoxicillin and co-amoxiclav) explain these discrepancies. CONCLUSIONS: The number of packages is a more appropriate measure than the number of DDDs when assessing outpatient antibiotic use over time and the impact of awareness campaigns in countries dispensing 'complete packages'. We recommended the use of different complementary measures or caution when interpreting trends based only on DDDs.

Patient and prescriber determinants for the choice between amoxicillin and broader-spectrum antibiotics: a nationwide prescription-level analysis.

OBJECTIVES: Bacterial resistance to antibiotics, driven by antibiotic consumption, imposes a major threat to the effective treatment of bacterial infections. In addition to reducing the amount of antibiotics prescribed, avoiding broad-spectrum antibiotics could extend the lifetime of the current arsenal of antibiotic substances. Therefore, we documented prescriber and patient characteristics associated with the choice between amoxicillin and broader-spectrum alternatives (co-amoxiclav or moxifloxacin) in recent years in Belgium. METHODS: Complete reimbursement claims data (2002-09) for antibiotic prescriptions in outpatient care, including patient and prescriber characteristics, were collected for both young children (1-5 years) and the adult population (30-60 years). A backwards selection procedure within generalized estimating equations retained the most relevant determinants. RESULTS: The age, gender and social category of the patient were found to be predictive of the extent to which amoxicillin was prescribed instead of the broader-spectrum alternatives, with female patients generally taking a higher proportion of amoxicillin than male patients. The age category of 40-44-year-old prescribers exhibited a preference for broad-spectrum antibiotics compared with both younger and older age groups. Significant interactions between the region and the prescriber's qualification (general practitioner or paediatrician) on the choice of antibiotic for children were found. CONCLUSIONS: Patient (age, gender and social category) and prescriber characteristics (age, gender, region and qualification) had an influence on whether amoxicillin or the alternative broad-spectrum antibiotics were prescribed. These findings should help policy makers to better target future campaigns to promote prudent prescribing of antibiotics.

Patterns of health care use and expenditure during the last 6 months of life in Belgium: differences between age categories in cancer and non-cancer patients.

OBJECTIVES: We analysed end-of-life care in Belgium to examine potential age variation in place of death, transitions between care settings, health care utilisation and public expenditure in the last 6 months of life. METHODS: Administrative data of one sickness fund were used, and analysed through regression analysis and analysis of variance. The study population comprised 40,794 individuals (age>40 years). RESULTS: Several indicators showed that the end-of-life of older people, especially of those aged >or=90 years, differs from that of younger individuals. Older persons more likely died in a care home, were less transferred between care settings, and stayed less days in hospital. On the other hand, older persons used more home care services, and had more contacts with the general practitioner. Differences between age categories were equally observed for last week's end-of-life care. Opposite to the trend for cancer patients, the odds of having a palliative home care allowance increased with age for non-cancer patients. Public expenditure for the oldest old was lower as compared to the younger decedents, but dependent on place of death. CONCLUSION: Several aspects of end-of-life care in Belgium appear to be influenced by age. In view of ageing of the population, these findings can be of interest to decision makers.

Greater impact of extreme drought on photosynthesis of grasslands exposed to a warmer climate in spite of acclimation.

In view of the projected increase in the frequency of extreme events during this century, we investigated the impact of a drought extreme on leaf ecophysiological parameters and carbon isotope composition (delta(13)C) of grassland communities with species richness (S) of one, three or nine species. The communities, grown for 3 years at either ambient air temperatures (ambient T(air)) or ambient T(air) + 3 degrees C (elevated T(air)), were additionally subjected to an imposed drought by withholding water for 24 days. During the previous 3 years equal precipitation was applied in both temperature treatments, thus communities at elevated T(air) had experienced more frequent, mild droughts. However, it was unknown whether this resulted in a higher resistance for facing extreme droughts. At similar soil matric potentials stomatal conductance (g(s)) and transpiration (Tr) were higher at elevated than ambient T(air), indicating acclimation to lower soil water content. Despite the stomatal acclimation observed, plants in elevated T(air) showed a lower resistance to the drought extreme as indicated by their lower photosynthetic rate (A(max)), g(s) and Tr during the entire duration of the drought extreme. Lower values for A(max), Tr and g(s) were also recorded in species at S = 3 as compared with species at S = 1 for both temperature treatments, but no further differences with S = 9 suggesting that stress was not alleviated at higher S-levels. The discrimination of (13)C was poorly correlated with measurements of instantaneous leaf water-use efficiency (A(max)/Tr) and, with this time scale and sampling method, it was not possible to detect any potential change in plant water-use efficiency using leaf delta(13)C.

Coppicing shifts CO2 stimulation of poplar productivity to above-ground pools: a synthesis of leaf to stand level results from the POP/EUROFACE experiment.

A poplar short rotation coppice (SRC) grown for the production of bioenergy can combine carbon (C) storage with fossil fuel substitution. Here, we summarize the responses of a poplar (Populus) plantation to 6 yr of free air CO(2) enrichment (POP/EUROFACE consisting of two rotation cycles). We show that a poplar plantation growing in nonlimiting light, nutrient and water conditions will significantly increase its productivity in elevated CO(2) concentrations ([CO(2)]). Increased biomass yield resulted from an early growth enhancement and photosynthesis did not acclimate to elevated [CO(2)]. Sufficient nutrient availability, increased nitrogen use efficiency (NUE) and the large sink capacity of poplars contributed to the sustained increase in C uptake over 6 yr. Additional C taken up in high [CO(2)] was mainly invested into woody biomass pools. Coppicing increased yield by 66% and partly shifted the extra C uptake in elevated [CO(2)] to above-ground pools, as fine root biomass declined and its [CO(2)] stimulation disappeared. Mineral soil C increased equally in ambient and elevated [CO(2)] during the 6 yr experiment. However, elevated [CO(2)] increased the stabilization of C in the mineral soil. Increased productivity of a poplar SRC in elevated [CO(2)] may allow shorter rotation cycles, enhancing the viability of SRC for biofuel production.

Molecular phenotyping of lignin-modified tobacco reveals associated changes in cell-wall metabolism, primary metabolism, stress metabolism and photorespiration.

Lignin is an important component of secondarily thickened cell walls. Cinnamoyl CoA reductase (CCR) and cinnamyl alcohol dehydrogenase (CAD) are two key enzymes that catalyse the penultimate and last steps in the biosynthesis of the monolignols. Downregulation of CCR in tobacco (Nicotiana tabacum) has been shown to reduce lignin content, whereas lignin in tobacco downregulated for CAD incorporates more aldehydes. We show that altering the expression of either or both genes in tobacco has far-reaching consequences on the transcriptome and metabolome. cDNA-amplified fragment length polymorphism-based transcript profiling, combined with HPLC and GC-MS-based metabolite profiling, revealed differential transcripts and metabolites within monolignol biosynthesis, as well as a substantial network of interactions between monolignol and other metabolic pathways. In general, in all transgenic lines, the phenylpropanoid biosynthetic pathway was downregulated, whereas starch mobilization was upregulated. CCR-downregulated lines were characterized by changes at the level of detoxification and carbohydrate metabolism, whereas the molecular phenotype of CAD-downregulated tobacco was enriched in transcript of light- and cell-wall-related genes. In addition, the transcript and metabolite data suggested photo-oxidative stress and increased photorespiration, mainly in the CCR-downregulated lines. These predicted effects on the photosynthetic apparatus were subsequently confirmed physiologically by fluorescence and gas-exchange measurements. Our data provide a molecular picture of a plant's response to altered monolignol biosynthesis.

Increases in nitrogen uptake rather than nitrogen-use efficiency support higher rates of temperate forest productivity under elevated CO2.

Forest ecosystems are important sinks for rising concentrations of atmospheric CO(2). In previous research, we showed that net primary production (NPP) increased by 23 +/- 2% when four experimental forests were grown under atmospheric concentrations of CO(2) predicted for the latter half of this century. Because nitrogen (N) availability commonly limits forest productivity, some combination of increased N uptake from the soil and more efficient use of the N already assimilated by trees is necessary to sustain the high rates of forest NPP under free-air CO(2) enrichment (FACE). In this study, experimental evidence demonstrates that the uptake of N increased under elevated CO(2) at the Rhinelander, Duke, and Oak Ridge National Laboratory FACE sites, yet fertilization studies at the Duke and Oak Ridge National Laboratory FACE sites showed that tree growth and forest NPP were strongly limited by N availability. By contrast, nitrogen-use efficiency increased under elevated CO(2) at the POP-EUROFACE site, where fertilization studies showed that N was not limiting to tree growth. Some combination of increasing fine root production, increased rates of soil organic matter decomposition, and increased allocation of carbon (C) to mycorrhizal fungi is likely to account for greater N uptake under elevated CO(2). Regardless of the specific mechanism, this analysis shows that the larger quantities of C entering the below-ground system under elevated CO(2) result in greater N uptake, even in N-limited ecosystems. Biogeochemical models must be reformulated to allow C transfers below ground that result in additional N uptake under elevated CO(2).

Increased nitrogen-use efficiency of a short-rotation poplar plantation in elevated CO(2) concentration.

We estimated nitrogen (N) use by trees of three poplar species exposed for 3 years to free air CO(2) enrichment (FACE) and determined whether the CO(2) treatment affected the future N availability of the plantation. Trees were harvested at the end of the first 3-year rotation and N concentration and content of woody tissues determined. Nitrogen uptake of fine roots and litter was measured throughout the first crop rotation. The results were related to previously published variations in soil N content during the same period. We estimated retranslocation from green leaves and processes determining N mobilization and immobilization, such as mineralization and nitrification, and N immobilization in litter and microbial biomass. In all species, elevated CO(2) concentration ([CO(2)]) significantly increased nitrogen-use efficiency (NUE; net primary productivity per unit of annual N uptake), decreased N concentration in most plant tissues, but did not significantly change cumulative N uptake by trees over the rotation. Total soil N was depleted more in elevated [CO(2)] than in ambient [CO(2)], although not significantly for all soil layers. The effect of elevated [CO(2)] was usually similar for all species, although differences among species were sometimes significant. During the first 3-year rotation, productivity of the plantation remained high in the elevated [CO(2)] treatment. However, we observed a potential reduction in N availability in response to elevated [CO(2)].

Effects of climate warming and species richness on photochemistry of grasslands.

In view of the projected climatic changes and the global decrease in plant species diversity, it is critical to understand the effects of elevated air temperature (T(air)) and species richness (S) on physiological processes in plant communities. Therefore, an experiment of artificially assembled grassland ecosystems, with different S (one, three or nine species), growing in sunlit climate-controlled chambers at ambient T(air) and ambient T(air) + 3 degrees C was established. We investigated whether grassland species would be more affected by midday high-temperature stress during summer in a warmer climate scenario. The effect of elevated T(air) was expected to differ with S. This was tested in the second and third experimental years by means of chlorophyll a fluorescence. Because acclimation to elevated T(air) would affect the plant's stress response, the hypothesis of photosynthetic acclimation to elevated T(air) was tested in the third year by gas exchange measurements in the monocultures. Plants in the elevated T(air) chambers suffered more from midday stress on warm summer days than those in ambient chambers. In absence of severe drought, the quantum yield of PSII was not affected by elevated T(air). Our results further indicate that species had not photosynthetically acclimated to a temperature increase of 3 degrees C after 3 years exposure to a warmer climate. Although effects of S and T(air) x S interactions were mostly not significant in our study, we expect that combined effects of T(air) and S would be important in conditions of severe drought events.

Chronic ozone exposure affects leaf senescence of adult beech trees: a chlorophyll fluorescence approach.

Accelerated leaf senescence is one of the harmful effects of elevated tropospheric ozone concentrations ([O(3)]) on plants. The number of studies dealing with mature forest trees is scarce however. Therefore, five 66-year-old beech trees (Fagus sylvatica L.) have been exposed to twice-ambient (2xambient) [O(3)] levels by means of a free-air canopy O(3) exposure system. During the sixth year of exposure, the hypothesis of accelerated leaf senescence in 2xambient [O(3)] compared with ambient [O(3)] trees was tested for both sun and shade leaves. Chlorophyll (chl) fluorescence was used to assess the photosynthetic quantum yield, and chl fluorescence images were processed to compare functional leaf homogeneity and the proportion of O(3)-injured leaf area (stipples) under ambient and 2xambient [O(3)] regimes. Based on the analysis of chl fluorescence images, sun leaves of both ambient and 2xambient [O(3)] trees had apparently developed typical necrotic O(3) stipples during high O(3) episodes in summer, while accelerated senescence was only observed with sun leaves of 2xambient [O(3)] trees. This latter effect was indicated along with a faster decrease of photosynthetic quantum yield, but without evidence of changes in non-photochemical quenching. Overall, treatment effects were small and varied among trees. Therefore, compared with ambient [O(3)], the consequence of the observed O(3)-induced accelerated leaf senescence for the carbon budget is likely limited.

Forest response to elevated CO2 is conserved across a broad range of productivity.

Climate change predictions derived from coupled carbon-climate models are highly dependent on assumptions about feedbacks between the biosphere and atmosphere. One critical feedback occurs if C uptake by the biosphere increases in response to the fossil-fuel driven increase in atmospheric [CO(2)] ("CO(2) fertilization"), thereby slowing the rate of increase in atmospheric [CO(2)]. Carbon exchanges between the terrestrial biosphere and atmosphere are often first represented in models as net primary productivity (NPP). However, the contribution of CO(2) fertilization to the future global C cycle has been uncertain, especially in forest ecosystems that dominate global NPP, and models that include a feedback between terrestrial biosphere metabolism and atmospheric [CO(2)] are poorly constrained by experimental evidence. We analyzed the response of NPP to elevated CO(2) ( approximately 550 ppm) in four free-air CO(2) enrichment experiments in forest stands. We show that the response of forest NPP to elevated [CO(2)] is highly conserved across a broad range of productivity, with a stimulation at the median of 23 +/- 2%. At low leaf area indices, a large portion of the response was attributable to increased light absorption, but as leaf area indices increased, the response to elevated [CO(2)] was wholly caused by increased light-use efficiency. The surprising consistency of response across diverse sites provides a benchmark to evaluate predictions of ecosystem and global models and allows us now to focus on unresolved questions about carbon partitioning and retention, and spatial variation in NPP response caused by availability of other growth limiting resources.

Carbon budget of Pinus sylvestris saplings after four years of exposure to elevated atmospheric carbon dioxide concentration.

To study the responses of Scots pine (Pinus sylvestris L.), a commercially important tree species in Europe, to future increases in atmospheric CO2 concentration ([CO2]), we grew saplings for 4 years in the ground in open-top chambers in ambient or ambient + 400 micromol mol(-1) CO2, without supplemental addition of nutrients and water. Carbon (C) budgets were developed for trees in both CO2 treatments based on productivity and biomass data obtained from destructive harvests at the end of the third and fourth years of treatment, and simulations of annual gross photosynthesis (P(tot)) and maintenance respiration by the model MAESTRA. Simulated P(tot) was enhanced by elevated [CO2], despite significant down-regulation of photosynthetic capacity. The subsequent increase in C uptake was allocated primarily to tissues with limited longevity (needles and fine roots), which explains why the measured annual increment in woody biomass did not differ between CO2 treatments. Thus, our results suggest that accelerated stem growth only occurs in the first 2 years in the presence of elevated [CO2] and that forest rotations will not be shortened significantly in response to increasing [CO2]. In elevated [CO2], a higher proportion of available C was allocated below ground, resulting in altered biomass distribution patterns. In trees of equal size, measured ratios of fine root/needle biomass and belowground/aboveground biomass were almost twice as large in the elevated [CO2] treatment. Although there are uncertainties in scaling from saplings to mature canopies, the data indicate that, in nutrient-limited Scots pine forests, elevated [CO2] is unlikely to accelerate tree growth significantly, but is likely to increase C inputs to soil.