Substantial uptake of nitrous oxide (N2O) by shoots of mature European beech.

Similar to soils, tree stems emit and consume nitrous oxide (N2O) from the atmosphere. Although tree leaves dominate tree surface area, they have been completely excluded from field N2O flux measurements and therefore their role in forest N2O exchange remains unknown. We explored the contribution of leaf fluxes to forest N2O exchange. We determined the N2O exchange of mature European beech (Fagus sylvatica) stems and shoots (i.e., terminal branches) and of adjacent forest floor, in a typical temperate upland forest in Germany. The beech stems, and particularly the shoots, acted as net N2O sinks (-0.254 ±â€¯0.827 µg N2O m-2 stem area h-1 and - 4.54 ±â€¯1.53 µg N2O m-2 leaf area h-1, respectively), while the forest floor was a net source (2.41 ±â€¯1.08 µg N2O m-2 soil area h-1). The unstudied tree shoots were identified as a significant contributor to the net ecosystem N2O exchange. Moreover, we revealed for the first time that tree leaves act as substantial N2O sinks. Although this is the first study of its kind, it is of global importance for the proper design of future flux studies in forest ecosystems worldwide. Our results demonstrate that excluding tree leaves from forest N2O flux measurements can lead to misinterpretation of tree and forest N2O exchange, and thus global forest greenhouse gas flux inventories.

Methane emission from stems of European beech (Fagus sylvatica) offsets as much as half of methane oxidation in soil.

Trees are known to be atmospheric methane (CH4 ) emitters. Little is known about seasonal dynamics of tree CH4 fluxes and relationships to environmental conditions. That prevents the correct estimation of net annual tree and forest CH4 exchange. We aimed to explore the contribution of stem emissions to forest CH4 exchange. We determined seasonal CH4 fluxes of mature European beech (Fagus sylvatica) stems and adjacent soil in a typical temperate beech forest of the White Carpathians with high spatial heterogeneity in soil moisture. The beech stems were net annual CH4 sources, whereas the soil was a net CH4 sink. High CH4 emitters showed clear seasonality in their stem CH4 emissions that followed stem CO2 efflux. Elevated CH4 fluxes were detected during the vegetation season. Observed high spatial variability in stem CH4 emissions was neither explicably by soil CH4 exchange nor by CH4 concentrations, water content, or temperature studied in soil profiles near each measured tree. The stem CH4 emissions offset the soil CH4 uptake by up to 46.5% and on average by 13% on stand level. In Central Europe, widely grown beech contributes markedly to seasonal dynamics of ecosystem CH4 exchange. Its contribution should be included into forest greenhouse gas flux inventories.

Long-term dynamics of soil, tree stem and ecosystem methane fluxes in a riparian forest.

The carbon (C) budgets of riparian forests are sensitive to climatic variability. Therefore, riparian forests are hot spots of C cycling in landscapes. Only a limited number of studies on continuous measurements of methane (CH4) fluxes from riparian forests is available. Here, we report continuous high-frequency soil and ecosystem (eddy-covariance; EC) measurements of CH4 fluxes with a quantum cascade laser absorption spectrometer for a 2.5-year period and measurements of CH4 fluxes from tree stems using manual chambers for a 1.5 year period from a temperate riparian Alnus incana forest. The results demonstrate that the riparian forest is a minor net annual sink of CH4 consuming 0.24 kg CH4-C ha-1 y-1. Soil water content is the most important determinant of soil, stem, and EC fluxes, followed by soil temperature. There were significant differences in CH4 fluxes between the wet and dry periods. During the wet period, 83% of CH4 was emitted from the tree stems while the ecosystem-level emission was equal to the sum of soil and stem emissions. During the dry period, CH4 was substantially consumed in the soil whereas stem emissions were very low. A significant difference between the EC fluxes and the sum of soil and stem fluxes during the dry period is most likely caused by emission from the canopy whereas at the ecosystem level the forest was a clear CH4 sink. Our results together with past measurements of CH4 fluxes in other riparian forests suggest that temperate riparian forests can be long-term CH4 sinks.

Trees as net sinks for methane (CH4 ) and nitrous oxide (N2 O) in the lowland tropical rain forest on volcanic Réunion Island.

Trees are known to emit methane (CH4 ) and nitrous oxide (N2 O), with tropical wetland trees being considerable CH4 sources. Little is known about CH4 and especially N2 O exchange of trees growing in tropical rain forests under nonflooded conditions. We determined CH4 and N2 O exchange of stems of six dominant tree species, cryptogamic stem covers, soils and volcanic surfaces at the start of the rainy season in a 400-yr-old tropical lowland rain forest situated on a basaltic lava flow (Réunion Island). We aimed to understand the unknown role in greenhouse gas fluxes of these atypical tropical rain forests on basaltic lava flows. The stems studied were net sinks for atmospheric CH4 and N2 O, as were cryptogams, which seemed to be co-responsible for the stem uptake. In contrast with more commonly studied rain forests, the soil and previously unexplored volcanic surfaces consumed CH4 . Their N2 O fluxes were negligible. Greenhouse gas uptake potential by trees and cryptogams constitutes a novel and unique finding, thus showing that plants can serve not only as emitters, but also as consumers of CH4 and N2 O. The volcanic tropical lowland rain forest appears to be an important CH4 sink, as well as a possible N2 O sink.

Short-term flooding increases CH4 and N2O emissions from trees in a riparian forest soil-stem continuum.

One of the characteristics of global climate change is the increase in extreme climate events, e.g., droughts and floods. Forest adaptation strategies to extreme climate events are the key to predict ecosystem responses to global change. Severe floods alter the hydrological regime of an ecosystem which influences biochemical processes that control greenhouse gas fluxes. We conducted a flooding experiment in a mature grey alder (Alnus incana (L.) Moench) forest to understand flux dynamics in the soil-tree-atmosphere continuum related to ecosystem N2O and CH4 turn-over. The gas exchange was determined at adjacent soil-tree-pairs: stem fluxes were measured in vertical profiles using manual static chambers and gas chromatography; soil fluxes were measured with automated chambers connected to a gas analyser. The tree stems and soil surface were net sources of N2O and CH4 during the flooding. Contrary to N2O, the increase in CH4 fluxes delayed in response to flooding. Stem N2O fluxes were lower although stem CH4 emissions were significantly higher than from soil after the flooding. Stem fluxes decreased with stem height. Our flooding experiment indicated soil water and nitrogen content as the main controlling factors of stem and soil N2O fluxes. The stems contributed up to 88% of CH4 emissions to the stem-soil continuum during the investigated period but soil N2O fluxes dominated (up to 16 times the stem fluxes) during all periods. Conclusively, stem fluxes of CH4 and N2O are essential elements in forest carbon and nitrogen cycles and must be included in relevant models.

Seasonal dynamics of stem N2O exchange follow the physiological activity of boreal trees.

The role of trees in the nitrous oxide (N2O) balance of boreal forests has been neglected despite evidence suggesting their substantial contribution. We measured seasonal changes in N2O fluxes from soil and stems of boreal trees in Finland, showing clear seasonality in stem N2O flux following tree physiological activity, particularly processes of CO2 uptake and release. Stem N2O emissions peak during the vegetation season, decrease rapidly in October, and remain low but significant to the annual totals during winter dormancy. Trees growing on dry soils even turn to consumption of N2O from the atmosphere during dormancy, thereby reducing their overall N2O emissions. At an annual scale, pine, spruce and birch are net N2O sources, with spruce being the strongest emitter. Boreal trees thus markedly contribute to the seasonal dynamics of ecosystem N2O exchange, and their species-specific contribution should be included into forest emission inventories.

Ratings of activities of daily living in nursing home residents: comparison of self- and proxy ratings with actual performance and the impact of cognitive status.

This study was conducted to examine differences between self- and proxy ratings of activities in daily living (ADL) in nursing home residents and to compare them with actual performance. An impact of cognitive status on these ratings was also determined. Data were obtained from 164 dyads of nursing home residents (self-ratings) and their professional care providers (proxy ratings). Statistical procedures included t tests, intraclass correlations, Pearson's correlations, analysis of variance (ANOVA) and ROC curves. Paired t test provided evidence that residents in general overestimated their abilities for all ADLs (p < .01 in all cases), but a substantial subset of 54 residents, with mean MMSE of 18, agreed with their care providers. The mean MMSE score of those who overestimated their abilities was 13 (N = 57). The ANOVA revealed that greater rating differences were associated with more severe cognitive impairment (MMSE, F = 9.93, p < .001). Proxy ratings of walking were not significantly different from actual performances (p = .145), while self-ratings overestimated it (p < .001). Although residents in general overestimated their ADL abilities and results of comparison with actual performance indicated that proxies may be closer to the actual status in this population, a considerable number of those with milder cognitive impairment were able to assess their ADLs with reasonable accuracy.

Cryptogamic stem covers may contribute to nitrous oxide consumption by mature beech trees.

Naturally produced by microbial processes in soil, nitrous oxide (N2O) is an important greenhouse gas contributing to climate change. Accordingly, there is a need to accurately quantify the capability of forest ecosystems to exchange N2O with the atmosphere. While N2O emissions from soils have been well studied, trees have so far been overlooked in N2O inventories. Here, we show that stems of mature beech trees (Fagus sylvatica) may act as a substantial sink of N2O from the atmosphere under conditions of soils consuming N2O. Consistent consumption of N2O by all stems investigated (ranging between -2.4 and -3.8 µg m-2 h-1) is a novel finding in contrast to current studies presenting trees as N2O emitters. To understand these fluxes, N2O exchange of photoautotrophic organisms associated with beech bark (lichens, mosses and algae) was quantified under laboratory conditions. All these organisms were net N2O sinks at full rehydration and temperature of 25 °C. The consumption rates were comparable to stem consumption rates measured under field conditions. Cryptogamic stem covers could be a relevant sink of N2O in European beech forests.

Dance as Prevention of Late Life Functional Decline Among Nursing Home Residents.

Late life deterioration of functional status is associated with adverse health outcomes and increased cost of care. This trial was conducted to determine whether dance-based intervention could reverse functional decline among nursing home (NH) residents. A total of 189 residents of seven NHs in the Czech Republic were randomly assigned to intervention and control groups. More detailed data were collected in a subsample of 52 participants. Intervention consisted of 3-month dance-based exercise. Functional status was assessed by the get-up-and-go test, basic activities of daily living (ADL), instrumental activities of daily living (IADL), and senior fitness tests (SFTs). Participants in the control group experienced a significant decline in get-up-and-go test, IADL, and in four of the six SFTs. The intervention proved to be effective in preventing this deterioration and improved chair stand test and chair sit-and-reach test. The findings indicate that a relatively simple dance-based exercise can slow down deterioration of functional status in NH residents.

Pinus sylvestris as a missing source of nitrous oxide and methane in boreal forest.

Boreal forests comprise 73% of the world's coniferous forests. Based on forest floor measurements, they have been considered a significant natural sink of methane (CH4) and a natural source of nitrous oxide (N2O), both of which are important greenhouse gases. However, the role of trees, especially conifers, in ecosystem N2O and CH4 exchange is only poorly understood. We show for the first time that mature Scots pine (Pinus sylvestris L.) trees consistently emit N2O and CH4 from both stems and shoots. The shoot fluxes of N2O and CH4 exceeded the stem flux rates by 16 and 41 times, respectively. Moreover, higher stem N2O and CH4 fluxes were observed from wet than from dry areas of the forest. The N2O release from boreal pine forests may thus be underestimated and the uptake of CH4 may be overestimated when ecosystem flux calculations are based solely on forest floor measurements. The contribution of pine trees to the N2O and CH4 exchange of the boreal pine forest seems to increase considerably under high soil water content, thus highlighting the urgent need to include tree-emissions in greenhouse gas emission inventories.

The effect of dance on depressive symptoms in nursing home residents.

OBJECTIVE: To evaluate the effect of a dance-based therapy on depressive symptoms among institutionalized older adults. DESIGN: Randomized controlled trial. SETTING: Nursing homes. PARTICIPANTS: Older adults (60 years or older) permanently living in a nursing home. INTERVENTION: Exercise Dance for Seniors (EXDASE) Program designed for the use in long-term care settings performed once a week for 60 minutes for 3 months. MEASUREMENTS: Baseline measures included sociodemographic characteristics, ability to perform basic as well as instrumental activities of daily living, basic mobility, self-rated health, and cognitive status. Outcome measures were collected before and after the intervention and included assessment of depressive symptoms using the geriatric depression scale (GDS). RESULTS: Comparison of participants with MMSE of 15 or higher showed that GDS scores in the intervention group significantly improved (P = .005), whereas the control group had a trend of further worsening of depressive symptoms (P = .081). GLM analysis documented highly statistically significant effect of dance therapy (P = .001) that was not influenced by controlling for intake of antidepressants and nursing home location. Dance therapy may have decreased depressive symptoms even in participants with MMSE lower than 15 and resulted in more discontinuations and fewer prescriptions of antidepressants in the intervention group than in the control group. CONCLUSION: This study provides evidence that dance-based exercise can reduce the amount of depressive symptoms in nursing home residents. In general, this form of exercise seems to be very suitable and beneficial for this population.

Walking Ability and Its Relationship to Self-Rated Health in Later Life.

This study investigated the relationship between self-assessed overall health (SRH) and walking ability among older adults (n = 239) gauged using three well-established measures of walking ability ("normal" and "fast" walking speeds, and perceived walking difficulty). Logistic regression models adjusted for health, behavioral, and sociodemographic variables were used to estimate the relationship between the three measures of walking ability and SRH. Walking ability was significantly associated with SRH; notably, only normal walking speed discriminated between participants in all three SRH comparisons (good versus poor/bad, good versus fair, or excellent versus good). Health care providers, family, and friends should be attentive to reduced walking speed or complaints about difficulty walking because these are harbingers of health decline.

Self-rated health among persons with spinal cord injury: what is the role of physical ability?

OBJECTIVES: Self-rated health (SRH) is a powerful concept that has greatly advanced our understanding of health and health outcomes. The SRH measure has become increasingly common in health research. Yet, puzzles remain about what shapes SRH ratings. The absence of knowledge is particularly acute in the context of disability. The aim of this study was to examine the relationship between SRH and self-rated physical ability in a sample of individuals with spinal cord injury (SCI). METHODS: Data from 140 eligible participants drawn from a study of life in the community after SCI were analyzed. The study, cross-sectional in design, was conducted in a large urban city in the mid-western United States. Basic statistics such as ANOVA and chi-square tests were performed as appropriate, and a multiple linear regression analysis modeled the relationship between SRH and physical ability adjusting for potential confounding variables. RESULTS: Self-rated physical ability was significantly associated with SRH after controlling for relevant covariates (P < 0.001). An analysis of the interaction between physical ability and level of injury revealed that the relationship was significant for persons with paraplegia but not for persons with tetraplegia. CONCLUSIONS: This study provides evidence that self-rated physical ability is an important factor associated with SRH for persons with SCI, but that the strength of the relationship depends on level of injury (paraplegia vs. tetraplegia). The challenge for future research is to replicate the study using a more comprehensive measure of physical ability and to ask how beliefs in one's ability to do those activities that are most meaningful and desired shape SRH. Only in this way will our understanding of the physical ability-SRH relationship be clarified.

Effect of the Exercise Dance for Seniors (EXDASE) program on lower-body functioning among institutionalized older adults.

OBJECTIVE: The authors conducted a randomized control trial to examine the effect of the Exercise Dance for Seniors (EXDASE) program on lower-body functioning among older individuals from residential care facilities in the Czech Republic. METHOD: Participants were randomly assigned into an experimental or control group. The experimental group completed a 3-month EXDASE program. Lower-body functioning was assessed using four performance-based measures. A 2 (group) x 2 (test) general linear model for repeated measures was used to explore whether differences in performance could be attributed to the intervention. RESULTS: The authors found Group x Test interactions for the chair stand test, F(1, 50) = 14.37, p < .001, the 2-minute step test, F(1, 50) = 7.33, p = .009, the chair sit-and-reach test, F(1, 50) = 5.28, p = .026, and the timed up-and-go test, F (1, 44) = 6.59, p = .014, indicating that the experimental group outperformed the control group from pretest to posttest. DISCUSSION: A relatively simple dance-based exercise can support lower-body functioning in previously sedentary, frail older adults.