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Objective The aim of this research was to explore the library and information needs of health and social care students whilst on placement. Methods Both desk and primary research were conducted and included an online questionnaire to students and semi-structured interviews. Results The questionnaire was completed by 252 students from a variety of programmes, equivalent to a 10% response rate. The results indicate a wide range of factors impacting on the library and information experiences of students. Whilst differences in the availability of a physical library in hospital or community locations still exist, these are mitigated by technology and a preference for home study. A significant result is that 77% ( n = 193) of students on placement study at home, using a variety of Internet-connected devices. This highlights a marked change in practice and underlines the need for mobile-compliant e-resources and accessible at-a-distance services. Conclusion As a result of this research, practical recommendations on how library support can be improved were developed including enhanced collaboration and learning with NHS colleagues, and knowledge sharing with other departments within the University who support our students. [ABSTRACT FROM AUTHOR]

Despite some success with microbial fuel cells and microbial electrolysis cells in recovering resources from wastes, challenges with their scale and yield need to be resolved. Waste streams from biorefineries e.g. bioethanol and biodiesel plants and wastewaters are plausible substrates for microbial electrosynthesis (MES). MES integration can help biorefineries achieving the full polygeneration potentials, i.e. recovery of metals turning apparently pollutants from biorefineries into resources, production of biofuels and chemicals from reuse of CO 2 and clean water. Symbiotic integration between the two systems can attain an economic and environmental upside of the overall system. We envision that electrochemical technologies and waste biorefineries can be integrated for increased efficiency and competitiveness with stillage released from the latter process used in the former as feedstock and energy resource recovered from the former used in the latter. Such symbiotic integration can avoid loss of material and energy from waste streams, thereby increasing the overall efficiency, economics and environmental performance that would serve towards delivering the common goals from both the systems. We present an insightful overview of the sources of organic wastes from biorefineries for integration with MES, anodic and cathodic substrates and biocatalysts. In addition, a generic and effective reaction and thermodynamic modelling framework for the MES has been given for the first time. The model is able to predict multi-component physico-chemical behaviour, technical feasibility and best configuration and conditions of the MES for resource recovery from waste streams. [ABSTRACT FROM AUTHOR]

The article discusses the lulu-correlation effect in plants. It states that the strong lulu-correlations can arise in a mechanistic modeling of photosynthesis-nutrient relationship. It cites that the effect represents a distinct but slightly overlapping trait dimensions. It also mentions the involvement of the photosynthetic characteristics and area-based associated in the structure and function of the photosynthetic machinery.

RATIONALE Pyrogenic carbon ( CP) is an important component of the global carbon budget. Accurate determination of the abundance and stable isotope composition of CP in soils and sediments is crucial for understanding the dynamics of the CP cycle and interpreting records of biomass burning, climate and vegetation change in the past. Here we test hydrogen pyrolysis (hypy) as a new technique potentially capable of eliminating labile organic carbon ( CL) from total organic carbon ( CT) in a range of matrices in order to enable reliable quantification of both the CP component of CT and the stable carbon isotope composition of CP ( δ13CP). METHODS We mixed CP at a range of concentrations with common CP-free matrices ( CL = cellulose, chitin, keratin, decomposed wood, leaf litter, grass and algae) and determined the amount of residual carbon not removed by hydrogen pyrolysis ( CR) as a ratio of CT ( CR/ CT). Mixing CP with a unique δ13C value provided a natural abundance isotope label from which to precisely determine the ratio of CP to residual CL remaining after hypy. RESULTS All CP-free matrices contained trace carbon after hypy, indicating that hypy does not remove all the CL. However, there was a strong correlation between CR/ CT and CP/ CT, viz. CR/ CT = 1.02( CP/ CT) + 4.0 × 10-3, r2 = 0.99, p <0.001, suggesting that only a small and reasonably constant fraction of CL remains after hypy. Uncertainties associated with the correction for contamination of CR by residual CL are minimal allowing for reliable determinations of both CP and δ13CP in many cases. CONCLUSIONS Hydrogen pyrolysis appears to be a robust technique for estimating CP abundance and δ13 CP across a range of materials. Nevertheless, caution is required in interpreting δ13 CP values when CP/ CT is low, with CP/ CT >4% being required for the determination of the δ13 CP values within an interpretable error under our experimental conditions. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Global environmental changes may be altering the ecology of tropical forests. Long-term monitoring plots have provided much of the evidence for large scale, directional changes in tropical forests, but the results have been controversial. Here we review evidence from six complementary approaches to understanding possible changes: plant physiology experiments, long-term monitoring plots, ecosystem flux techniques, atmospheric measurements, Earth observations, and global-scale vegetation models. Evidence from four of these approaches suggests that large-scale, directional changes are occurring in the ecology of tropical forests, with the other two approaches providing inconclusive results. Collectively, the evidence indicates that both gross and net primary productivity has likely increased over recent decades as have tree growth, recruitment, and mortality rates, and forest biomass These results suggest a profound reorganization of tropical forest ecosystems. We evaluate the most likely drivers of the suite of changes, and suggest increasing resource availability, potentially from rising atmospheric CO2 concentrations, is the most likely cause. [ABSTRACT FROM AUTHOR]

To estimate the relative contributions of woody and herbaceous vegetation to savanna productivity, we measured the 13C/12C isotopic ratios of leaves from trees, shrubs, grasses and the surface soil carbon pool for 22 savannas in Australia, Brazil and Ghana covering the full savanna spectrum ranging from almost pure grassland to closed woodlands on all three continents. All trees and shrubs sampled were of the C3 pathway and all grasses of the C3 pathway with the exception of Echinolaena inflexa (Poir.) Chase, a common C3 grass of the Brazilian cerrado. By comparing the carbon isotopic compositions of the plant and carbon pools, a simple model relating soil δ13C to the relative abundances of trees + shrubs (woody plants) and grasses was developed. The model suggests that the relative proportions of a savanna ecosystem's total foliar projected cover attributable to grasses versus woody plants is a simple and reliable index of the relative contributions of grasses and woody plants to savanna net productivity. Model calibrations against woody tree canopy cover made it possible to estimate the proportion of savanna productivity in the major regions of the world attributable to trees + shrubs and grasses from ground-based observational maps of savanna woodiness. Overall, it was estimated that 59% of the net primary productivity (Np) of tropical savannas is attributable to C4 grasses, but that this proportion varies significantly within and between regions. The C4 grasses make their greatest relative contribution to savanna Np in the Neotropics, whereas in African regions, a greater proportion of savanna Np is attributable to woody plants. The relative contribution of C4 grasses in Australian savannas is intermediate between those in the Neotropics and Africa. These differences can be broadly ascribed to large scale differences in soil fertility and rainfall. [ABSTRACT FROM AUTHOR]

A knowledge of the distribution of the contribution of upwind sources to measurements of vertical scalar flux densities is important for the correct interpretation of eddy covariance data. Several approaches have been developed to estimate this so-called footprint function. Here a new approach based on the ensemble-averaged Navier--Stokes equations is presented. Comparisons of numerical results using this approach with results from other studies under a range of environmental conditions show that the model predictions are robust. Moreover, the approach outlined here has the advantage of a potential wide applicability, due to an ability to take into account the heterogeneous nature of underlying surfaces. For example, the model showed that any variations in surface drag, such as must occur in real life heterogeneous canopies, can exert a marked influence of the shape and extent of flux footprints. Indeed, it seems likely that under such circumstances, estimates of surface fluxes will be weighted towards areas of highest foliage density (and therefore quite likely higher photosynthetic rates) close to the measurement sensor. Three-dimensional footprints during the day and night were also determined for a mixed coniferous forest in european Russia. A marked asymmetry of the footprint in the crosswind direction was observed, this being especially pronounced for non-uniform plant distributions involving vegetation types with different morphological and physiological properties. The model also found that, other things being equal, the footprint peak for forest soil respiration is typically over twice the distance from the above canopy measurement sensor compared to that for canopy photosynthesis. This result has important consequences for the interpretation of annual ecosystem carbon balances by the eddy covariance method. [ABSTRACT FROM AUTHOR]

Presents information on a study which compared the budget methods for inferring surface carbon dioxide fluxes and oxygen isotope discrimination during carbon dioxide over a forest and bog region in central Siberia in July 1998. Description of the budget methods; Results and discussion; Conclusions.

Presents information on a study which determined the vertical profiles of temperature, humidity and carbon dioxide concentration for atmosphere above a flux measurement tower near Zotino in central Siberia. Materials and methods; Results and discussion; Conclusions.

Presents information on a study which investigated the relationship between a physiological index called the photochemical index and photosynthetic light-use-efficiency of a Siberian boreal forest during the winter-spring transition in 2000. Site characteristics; Materials and methods; Results and discussion; Conclusions.

Presents information on a study which analyzed seasonal patterns in net ecosystems exchange of a Pinus sylvestris near Zotino in central Siberia. Examination of the relationship between canopy and photosynthesis; Materials and methods; Results and discussion; Conclusions.

Presents information on a study which determined the annual respiratory fluxes attributable to soil, stems and foliage for a Scots pine forest in central Siberia using a ground-based and above-canopy eddy covariance system. Ecosystem carbon budget for a Scots pine forest in central Siberia; Materials and methods; Results and discussion; Conclusions.

Presents information on a study which measured the rates of carbon dioxide efflux from the floor of a central Siberian Scots pine forest using a dynamic closed chamber system and eddy covariance system. Seasonal and spatial patterns of soil respiration underneath a stand of Scots pine; Materials and methods; Results and discussion; Conclusions.

Clarifies several issues regarding the impact of atmospheric carbon dioxide on slow-growing species and nutrient-stressed plants. Contrasting nature of photosynthetic and growth responses to elevated carbon dioxide; Nitrogen nutrition; Plant growth rate.

Focuses on the use of microorganisms for the remediation of neptunium(V) (Np(V)) solutions. Biocrystallization process; Microorganisms and culture conditions; Reduction of Np(V) by washed cell suspensions and ascorbic acid; Chromatographic separation of tri, tetra- and pentavalent actinides.

Leaf gas exchange, water relations and ion content were measured on two-year-old Valencia orange (Citrus sinensis [L.] Osbeck), Washington Navel orange (C. sinensis) and Marsh grapefruit (C. paradisi Macfad.) scions budded to either Trifoliata (Poncirus trifoliata [L.] Raf) or Cleopatra mandarin (C. reticulata Blanco) rootstocks. Trees were watered with dilute nutrient solution containing either 0 or 50 mM NaCl for 77 days. Leaf chloride concentrations (cell sap basis) were higher in all scions budded on Trifoliata but sodium levels were tower than in equivalent foliage budded on Cleopatra mandarin rootstock. Foliar salt levels also varied according to scion. Leaves of Marsh grapefruit had higher levels of both sodium and chloride than leaves of either Valencia orange or Washington Navel orange on both rootstocks. Accumulation of sodium and chloride in salinised leaves caused a reduction in leaf osmotic potential of 0.2-1.4 MPa, and leaf water potential declined by as much as 0.5 MPa. Turgor pressure in salinised leaves was thus maintained at or above the control level. Osmotic potentials determined by psychrometry compared with pressure-volume curves were taken to imply that some accumulation of sodium or chloride in the apoplast of salinised leaves may have occurred. Despite turgor maintenance, both CO2 assimilation and stomatal conductance were reduced by salinity. Following onset of leaf response to salinisation, gas exchange was impaired to a greater extent in scions budded to Cleopatra mandarin compared to those on Trifoliata. Amongst those scions, leaves of salt-treated Marsh grapefruit showed greater reductions in gas exchange than Valencia orange or Washington Navel orange budded on either rootstock. Increased sensitivity of Marsh grapefruit was correlated with a higher foliar sodium and chloride content in this scion. Scion differences in sensitivity of leaf gas exchange to solute concentration were independent of rootstock and appeared unrelated to leaf prolinebetaine concentrations. This implies an inherent difference between scion species with respect to salt tolerance, rather than variation in their capacity to acquire that type of compatible solute. In terms of rootstock effects, all scions proved more sensitive to salinity when budded to Cleopatra mandarin compared with Trifoliata. That response was attributed to a disproportionately higher concentration of leaf sodium in scions on Cleopatra mandarin. [ABSTRACT FROM AUTHOR]

Investigates the global distribution of oxygen isotopes in carbon dioxide. Isotopic exchange fluxes; Spatial variation; Places where precipitation (and soil water) is most depleted; Atmospheric carbon dioxide at high northern latitudes; Additional information.

A recent Ecology Letters paper of Fisher et al. (2008) utilized a modelling framework to investigate disturbance effects on forest biomass dynamics. But it contains serious methodological and conceptual errors. Associated conclusions are unlikely to be correct. [ABSTRACT FROM AUTHOR]

Provides evidence that periplasmic 9.6-kilodalton (kDa) c-type cytochrome of Geobacter sulfurreducens is not an electron shuttle to Fe(III) oxides. C-type cytochrome as 41-kDa cytochrome; Effects of Fe(III) microbial reduction to Fe(II) on natural and organic contaminant oxidation; Role of dissimilatory Fe(III) reduction on microbial respiration.

Presents information on a study which describes the enzymatic recovery of elemental palladium by using sulfate-reducing bacteria called Desulfovibrio desulfuricans. Methodology of the study; Results and discussion.

Features a study measuring the carbon dioxide flux in the undisturbed tropical rain forest in Southwest Amazonia during the wet and dry seasons of 1992 and 1993. Methods used in the study; Indication on the ecosystem as an absorber of carbon dioxide.

Discusses that technologies for remediation of polluted environments that rely on nonbiological, physical chemical approaches are often cost prohibitive. Significance of microorganisms that can convert toxic organic compounds to harmless products; Mechanism of metal-sequestering microbes; Metal-binding capabilities of Ralstonia eutropha.

Summary: The architecture of root systems is an important driver of plant fitness, competition and ecosystem processes. However, the methodological difficulty of mapping roots hampers the study of these processes. Existing approaches to match individual plants to belowground samples are low throughput and species specific. Here, we developed a scalable sequencing‐based method to map the root systems of individual trees across multiple species. We successfully applied it to a tropical dry forest community in the Brazilian Caatinga containing 14 species.We sequenced all 42 individual shrubs and trees in a 14 × 14 m plot using double‐digest restriction site‐associated sequencing (ddRADseq). We identified species‐specific markers and individual‐specific haplotypes from the data. We matched these markers to the ddRADseq data from 100 mixed root samples from across the centre (10 × 10 m) of the plot at four different depths using a newly developed R package.We identified individual root samples for all species and all but one individual. There was a strong significant correlation between belowground and aboveground size measurements, and we also detected significant species‐level root‐depth preference for two species.The method is more scalable and less labour intensive than the current techniques and is broadly applicable to ecology, forestry and agricultural biology. See also the Commentary on this article by Jones, 238: 924–925. [ABSTRACT FROM AUTHOR]

Discusses carbon-dioxide in the Amazon Basin. The question of whether Amazonia is a carbon-dioxide source or sink and its significance on estimates of the global carbon budget; Suggestion that El Nino, and its influence on precipitation in the region, seems to be the controlling factor.

Several graphs are presented related to the relationship between photosynthesis and nitrogen in tropical forest tree species, including carbon dioxide response curves, scatterplot between photosynthesis capacity and ambient, and random intercept mixed effects model.

Tropical soils are often characterised by low phosphorus availability and tropical forest trees typically exhibit lower area-based rates of photosynthesis (A[sub a]) for a given area-based leaf nitrogen concentration ([N][sub a]) compared with plants growing in higher-latitude, N-limited ecosystems. Nevertheless, to date, very few studies have assessed the effects of P deprivation per se on A[sub a] ↔ [N][sub a] relationships in tropical trees. Our study investigated the effect of reduced soil P availability on light-saturated A[sub a] and related leaf traits of seven Australian tropical tree species. We addressed the following questions: (1) Do contrasting species exhibit inherent differences in nutrient partitioning and morphology? (2) Does P deprivation lead to a change in the nature of the A[sub a] ↔ [N][sub a] relationship? (3) Does P deprivation lead to an alteration in leaf nitrogen levels or N allocation within the leaf? Applying a mixed effects model, we found that for these Australian tropical tree species, removal of P from the nutrient solution decreased area-based photosynthetic capacity (A[sub max,a]) by 18% and reduced the slope of the A[sub max,a] ↔ [N][sub a] relationship and differences among species accounted for around 30% of response variation. Despite greater N allocation to chlorophyll, photosynthetic N use efficiency was significantly reduced in low-P plants. Collectively, our results support the view that low soil P availability can alter photosynthesis-nitrogen relationships in tropical trees. [ABSTRACT FROM AUTHOR]

Abstract: Recent advances in our understanding of the linkages between plant physiological and morphological traits suggest a new means by which to define Plant Functional Types (Φ) for use in conceptual and mathematical models of vegetation dynamics. In this study we used data from the RAINFOR-network database, aiming to numerically derive Φ for tropical forest trees by jointly analysing an Amazon-wide dataset of (409) species abundance, species functional traits (10) and site edaphic and climatic conditions across 53 plots. We followed a stepwise procedure of numerical Φ definition with increasing complexity, starting from a simple PCA on species functional traits. We subsequently applied a three-table (RLQ) multivariate ordination method in two ways: with and without spatial autocorrelation between plots being taken into account. In all cases the environmental contribution to trait variation had been partialled out. Thus our results link species-specific “inherent” trait values with associated species abundances along environmental gradients. Our final classification of Amazonian tree species based on foliar dry leaf mass per area (M A), leaf concentrations of C, N, P, Ca, K, Mg, carbon isotopic discrimination (Δ), branch xylem density (ρ X ) and maximum tree height (H max) yielded four discrete Φ. These Φ were found to represent distinct life-history strategies and can be aligned with previous empirical definitions of tropical tree guilds. In particular, two ecological dimensions are identified: (1) a leaf deployment dimension which co-varies with soil fertility and (2) a stem deployment dimension which co-varies with soil texture. By analysing diameter growth rates of the same trees used to define the four Φ we found each Φ to have a different overall growth pattern. Furthermore, from a Basin-wide forest survey, differences in the relative abundance of the four Φ were related to stand level basal area growth and/or turnover rate variations. These new derived Φ should enhance our ability to better understand and model the dynamics of the Amazon forest, with the general procedure for plant functional trait definition described here potentially applicable to many other ecosystems. [Copyright &y& Elsevier]

The existence of many types of monodominant forests is readily explainable by ecological theory (e.g. early successional forests). Nevertheless, monodominant stands sometimes occur in areas where a much higher diversity typically occurs. Such 'classical monodominance' is not currently readily explained by ecological theory. We briefly review the published mechanisms suggested to cause classical monodominance and then combine them into a new probabilistic conceptual framework to better understand why these systems occur. We build on two theories proposed to explain monodominance: a lack of exogenous disturbance over long periods and species-specific life-history traits. We suggest that certain traits under certain conditions may generate positive feedbacks leading to a greater probability of monodominance being achieved. Such positive feedbacks have the potential to drive a typically diverse system towards a monodominant one. Synthesis. Classical monodominance in tropical forests is hypothesized to be attained when a group of traits occur together under low exogenous disturbance conditions, this giving rise to a series of positive feedbacks. The presented framework links the differing mechanisms proposed in the literature to explain classical monodominance and shows there are potentially alternative routes to monodominance, thus reconciling apparently contradictory observational and experimental results. [ABSTRACT FROM AUTHOR]

Background: Soil characteristics have been hypothesised as one of the possible mechanisms leading to monodominance of Gilbertiodendron dewerei in some areas of Central Africa where higher-diversity forest would be expected. However, the differences in soil characteristics between the G. dewevrei-dominated forest and its adjacent mixed forest are still poorly understood. Here we present the soil characteristics of the G. dewevrei forest and quantify whether soil physical and chemical properties in this monodominant forest are significantly different from the adjacent mixed forest. Methodology/Principal Findings: We sampled top soil (0-5, 5-10, 10-20, 20-30 cm) and subsoil (150-200 cm) using an augur in 6x1 ha areas of intact central Africa forest in SE Cameroon, three independent patches of G. dewevrei-dominated forest and three adjacent areas (450-800 m apart), all chosen to be topographically homogeneous. Analysis - subjected to Bonferroni correction procedure - revealed no significant differences between the monodominant and mixed forests in terms of soil texture, median particle size, bulk density, pH, carbon (C) content, nitrogen (N) content, C:N ratio, C:total NaOHextractable P ratio and concentrations of labile phosphorous (P), inorganic NaOH-extractable P, total NaOH-extractable P, aluminium, barium, calcium, copper, iron, magnesium, manganese, molybdenum, nickel, potassium, selenium, silicon, sodium and zinc. Prior to Bonferroni correction procedure, there was a significant lower level of silicon concentration found in the monodominant than mixed forest deep soil; and a significant lower level of nickel concentration in the monodominant than mixed forest top soil. Nevertheless, these were likely to be the results of multiple tests of significance. Conclusions/Significance: Our results do not provide clear evidence of soil mediation for the location of monodominant forests in relation to adjacent mixed forests. It is also likely that G. dewevrei does not influence soil chemistry in the monodominant forests. [ABSTRACT FROM AUTHOR]

• An earlier onset of photosynthesis in spring for boreal forest trees is predicted as the climate warms, yet the importance of soil vs air temperatures for spring recovery remains to be determined. Effects of various soil- and air-temperature conditions on spring recovery of photosynthesis in Scots pine ( Pinus sylvestris) seedlings were assessed under controlled environmental conditions. • Using winter-acclimated seedlings, photosynthetic responses were followed after transfer to different simulated spring conditions. • Recovery rates for photosynthetic electron transport and net CO2 uptake were slower in plants from cold or frozen soil compared with controls. In addition, a greater fraction of light absorbed was not used photochemically, but was dissipated thermally via xanthophyll cycle pigments. Intermittent frost events decreased photosynthetic capacity and increased thermal energy dissipation. Within a few days after frost events, photosynthetic capacity recovered to prefrost levels. After 18 d under spring conditions, no difference in the optimum quantum yield of photosynthesis was observed between seedlings that had been exposed to intermittent frost and control plants. • These results show that, if air temperatures remain favourable and spells of subfreezing air temperatures are only of short duration, intermittent frost events delay but do not severely inhibit photosynthetic recovery in evergreen conifers during spring. Cold and/or frozen soils exert much stronger inhibitory effects on the recovery process, but they do not totally inhibit it. [ABSTRACT FROM AUTHOR]

We studied the seasonal variation in carbon dioxide, water vapour and energy fluxes in a broad-leafed semi-arid savanna in Southern Africa using the eddy covariance technique. The open woodland studied consisted of an overstorey dominated by Colophospermum mopane with a sparse understorey of grasses and herbs. Measurements presented here cover a 19-month period from the end of the rainy season in March 1999 to the end of the dry season September 2000. During the wet season, sensible and latent heat fluxes showed a linear dependence on incoming solar radiation ( I) with a Bowen ratio ( β) typically just below unity. Although β was typically around 1 at low incoming solar radiation (150 W m−2) during the dry season, it increased dramatically with I, typically being as high as 4 or 5 around solar noon. Thus, under these water-limited conditions, almost all available energy was dissipated as sensible, rather than latent heat. Marked spikes of CO2 release occurred at the onset of the rainfall season after isolated rainfall events and respiration dominated the balance well into the rainfall season. During this time, the ecosystem was a constant source of CO2 with an average flux of 3–5 μmol m−2 s−1 to the atmosphere during both day and night. But later in the wet season, for example, in March 2000 under optimal soil moisture conditions, with maximum leaf canopy development (leaf area index 0.9–1.3), the peak ecosystem CO2 influx was as much as 10 μmol m−2 s−1. The net ecosystem maximum photosynthesis at this time was estimated at 14 μmol m−2 s−1, with the woodland ecosystem a significant sink for CO2. During the dry season, just before leaf fall in August, maximum day- and night-time net ecosystem fluxes were typically −3 μmol m−2 s−1 and 1–2 μmol m−2 s−1, respectively, with the ecosystem still being a marginal sink. Over the course of 12 months (March 1999–March 2000), the woodland was more or less carbon neutral, with a net uptake estimated at only about 1 mol C m−2 yr−1. The annual net photosynthesis (gross primary production) was estimated at 32.2 mol m−2 yr−1. [ABSTRACT FROM AUTHOR]

Objectives. We examined patron responses to a California smoke-free bar law. Methods. Three telephone surveys measured attitudes and behavior changes after implementation of the law. Results. Approval of the law rose from 59.8% to 73.2% (odds ratio [OR]= 1.95; 95% confidence interval [CI]=1.58, 2.40). Self-reported noncompliance decreased from 24.6% to 14.0% (OR=0.50; 95% CI=0.30, 0.85). Likelihood of visiting a bar or of not changing bar patronage after the law was implemented increased from 86% to 91% (OR=1.76; 95% CI=1.29, 2.40). Conclusions. California bar patrons increasingly support and comply with the smoke-free bar law. (Am J Public Health. 2003;93:611-617) [ABSTRACT FROM AUTHOR]

Keywords: alternative stable states; feedbacks; fire ecology; forest; savannah EN alternative stable states feedbacks fire ecology forest savannah 14 18 5 06/05/21 20210701 NES 210701 In their comment on Veenendaal I et al i . Sharp ecotones spark sharp ideas: comment on "Structural physiognomic and above-ground biomass variation in savanna-forest transition zones on three continents - how different are co-occurring savanna and forest formations?" (2003) have suggested the opposite trend for more arid savannas with lower tree cover, and our own analysis suggests that for more mesic vegetation types fire can only maintain open savanna grasslands under deliberate human-mediated, high-frequency, late season fire regimes. Fire regimes, fire experiments and alternative stable states in mesic savannas: A response to Laris & Jacobs (2021) "On the problem of natural savanna fires". [Extracted from the article]

Societal Impact Statement: Understanding of tropical forests has been revolutionized by monitoring in permanent plots. Data from global plot networks have transformed our knowledge of forests' diversity, function, contribution to global biogeochemical cycles, and sensitivity to climate change. Monitoring has thus far been concentrated in rain forests. Despite increasing appreciation of their threatened status, biodiversity, and importance to the global carbon cycle, monitoring in tropical dry forests is still in its infancy. We provide a protocol for permanent monitoring plots in tropical dry forests. Expanding monitoring into dry biomes is critical for overcoming the linked challenges of climate change, land use change, and the biodiversity crisis. [ABSTRACT FROM AUTHOR]

Summary: Over recent decades, biomass gains in remaining old-growth Amazonia forests have declined due to environmental change. Amazonia's huge size and complexity makes understanding these changes, drivers, and consequences very challenging. Here, using a network of permanent monitoring plots at the Amazon–Cerrado transition, we quantify recent biomass carbon changes and explore their environmental drivers. Our study area covers 30 plots of upland and riparian forests sampled at least twice between 1996 and 2016 and subject to various levels of fire and drought. Using these plots, we aimed to: (1) estimate the long-term biomass change rate; (2) determine the extent to which forest changes are influenced by forest type; and (3) assess the threat to forests from ongoing environmental change. Overall, there was no net change in biomass, but there was clear variation among different forest types. Burning occurred at least once in 8 of the 12 riparian forests, while only 1 of the 18 upland forests burned, resulting in losses of carbon in burned riparian forests. Net biomass gains prevailed among other riparian and upland forests throughout Amazonia. Our results reveal an unanticipated vulnerability of riparian forests to fire, likely aggravated by drought, and threatening ecosystem conservation at the Amazon southern margins. [ABSTRACT FROM AUTHOR]

Most of the planet's diversity is concentrated in the tropics, which includes many regions undergoing rapid climate change. Yet, while climate‐induced biodiversity changes are widely documented elsewhere, few studies have addressed this issue for lowland tropical ecosystems. Here we investigate whether the floristic and functional composition of intact lowland Amazonian forests have been changing by evaluating records from 106 long‐term inventory plots spanning 30 years. We analyse three traits that have been hypothesized to respond to different environmental drivers (increase in moisture stress and atmospheric CO2 concentrations): maximum tree size, biogeographic water‐deficit affiliation and wood density. Tree communities have become increasingly dominated by large‐statured taxa, but to date there has been no detectable change in mean wood density or water deficit affiliation at the community level, despite most forest plots having experienced an intensification of the dry season. However, among newly recruited trees, dry‐affiliated genera have become more abundant, while the mortality of wet‐affiliated genera has increased in those plots where the dry season has intensified most. Thus, a slow shift to a more dry‐affiliated Amazonia is underway, with changes in compositional dynamics (recruits and mortality) consistent with climate‐change drivers, but yet to significantly impact whole‐community composition. The Amazon observational record suggests that the increase in atmospheric CO2 is driving a shift within tree communities to large‐statured species and that climate changes to date will impact forest composition, but long generation times of tropical trees mean that biodiversity change is lagging behind climate change. Tropical forests are getting hotter—and in places drying—but how are they responding to the changing climate? A new analysis assesses long‐term records of thousands of tree species from across the vast Amazon basin. The team of 102 researchers discovered subtle but troubling changes in forest communities since the 1980s: trees preferring the wettest conditions and humid understorey are now in decline. With drought‐resistant plants gaining too slowly to track the changing climate Amazon forests appear increasingly vulnerable. [ABSTRACT FROM AUTHOR]

Increased drought is forecasted for tropical regions, with severe implications for the health and function of forest ecosystems. How mature forest trees will respond to water deficit is poorly known. We investigated wood anatomy and leaf traits in lowland tropical forest trees after 24 months of experimental rainfall exclusion. Sampling sun‐exposed young canopy branches from target species, we found species‐specific systematic variation in hydraulic‐related wood anatomy and leaf traits in response to drought stress. Relative to controls, drought‐affected individuals of different tree species variously exhibited trait measures consistent with increasing hydraulic safety. These included narrower or less vessels, reduced vessel groupings, lower theoretical water conductivities, less water storage tissue and more abundant fiber in their wood, and more occluded vessels. Drought‐affected individuals also had thinner leaves, and more negative pre‐dawn or mid‐day leaf water potentials. Future studies examining both wood and leaf hydraulic traits should improve the representation of plant hydraulics within terrestrial ecosystem and biosphere models, and help fine‐tune predictions of how future climate changes will affect tropical forests globally. Understanding how tropical rainforest trees will respond to climate change is important given worrisome projection drought events in tropical regions. We found that mature tropical trees can modify their water transport mechanisms when exposed to drought, at least in the short term. These results allow us to highlight complexities for understanding plant responses to climate change. [ABSTRACT FROM AUTHOR]

Highlights • Leastcost and coordination hypotheses support species strategy and ecosystem function. • An alternative framework of classifying dynamic roles based in plant traits. • Trait variation was linked to climate within a narrow tropical climatic range. • Optimality concepts and forest dynamics may represent PFTs more faithfully in DGVMs. Abstract The conventional representation of Plant Functional Types (PFTs) in Dynamic Global Vegetation Models (DGVMs) is increasingly recognized as simplistic and lacking in predictive power. Key ecophysiological traits, including photosynthetic parameters, are typically assigned single values for each PFT while the substantial trait variation within PFTs is neglected. This includes continuous variation in response to environmental factors, and differences linked to spatial and temporal niche differentiation within communities. A much stronger empirical basis is required for the treatment of continuous plant functional trait variation in DGVMs. We analyse 431 sets of measurements of leaf and plant traits, including photosynthetic measurements, on evergreen angiosperm trees in tropical moist forests of Australia and China. Confining attention to tropical moist forests, our analysis identifies trait differences that are linked to vegetation dynamic roles. Coordination theory predicts that Rubisco- and electron-transport limited rates of photosynthesis are co-limiting under field conditions. The least-cost hypothesis predicts that air-to-leaf CO 2 drawdown minimizes the combined costs per unit carbon assimilation of maintaining carboxylation and transpiration capacities. Aspects of these predictions are supported for within-community trait variation linked to canopy position, just as they are for variation along spatial environmental gradients. Trait differences among plant species occupying different structural and temporal niches may provide a basis for the ecophysiological representation of vegetation dynamics in next-generation DGVMs. [ABSTRACT FROM AUTHOR]

Summary: We assessed data from 11 experiments examining the effects of the timing and/or frequency of fire on tropical forest and/or savanna vegetation structure over one decade or more. The initial ‘control treatment’ in many such cases consisted of previously cleared land. This is as opposed to natural vegetation subject to some sort of endogenous fire regime before the imposition of fire treatments. Effects of fire on fractional foliar cover are up to 10‐fold greater when clearing pre‐treatments are imposed. Moreover, because many of the ‘classic’ fire trials were initialised with applied management questions in mind, most have also used burning regimes much more frequent and/or severe than those occurring in the absence of human activity. Once these factors are taken into account, our modelling analysis shows that nonanthropogenic fire regimes serve to reduce canopy vegetative cover to a much lower extent than has previously been argued to be the case. These results call into question the notion that fire effects on tropical vegetation can be of a sufficient magnitude to maintain open‐type savanna ecosystems under climatic/soil regimes otherwise sufficient to give rise to a more luxurious forest‐type vegetation cover. [ABSTRACT FROM AUTHOR]

In their recent paper, Staver and Hansen ( Global Ecology and Biogeography, 2015, 24, 985-987) refute the case made by Hanan et al. ( Global Ecology and Biogeography, 2014, 23, 259-263) that the use of classification and regression trees (CARTs) to predict tree cover from remotely sensed imagery (MODIS VCF) inherently introduces biases, thus making the resulting tree cover unsuitable for showing alternative stable states through tree cover frequency distribution analyses. Here we provide a new and equally fundamental argument for why the published frequency distributions should not be used for such purposes. We show that the practice of pre-average binning of tree cover values used to derive cover values to train the CART model will also introduce errors in the frequency distributions of the final product. We demonstrate that the frequency minima found at tree covers of 8-18%, 33-45% and 55-75% can be attributed to numerical biases introduced when training samples are derived from landscapes containing asymmetric tree cover distributions and/or a tree cover gradient. So it is highly likely that the CART, used to produce MODIS VCF, delivers tree cover frequency distributions that do not reflect the real world situation. [ABSTRACT FROM AUTHOR]

We examined whether variations in photosynthetic capacity are linked to variations in the environment and/or associated leaf traits for tropical moist forests ( TMFs) in the Andes/western Amazon regions of Peru., We compared photosynthetic capacity (maximal rate of carboxylation of Rubisco ( Vcmax), and the maximum rate of electron transport ( Jmax)), leaf mass, nitrogen (N) and phosphorus (P) per unit leaf area ( Ma, Na and Pa, respectively), and chlorophyll from 210 species at 18 field sites along a 3300-m elevation gradient. Western blots were used to quantify the abundance of the CO2-fixing enzyme Rubisco., Area- and N-based rates of photosynthetic capacity at 25°C were higher in upland than lowland TMFs, underpinned by greater investment of N in photosynthesis in high-elevation trees. Soil [P] and leaf Pa were key explanatory factors for models of area-based Vcmax and Jmax but did not account for variations in photosynthetic N-use efficiency. At any given Na and Pa, the fraction of N allocated to photosynthesis was higher in upland than lowland species. For a small subset of lowland TMF trees examined, a substantial fraction of Rubisco was inactive., These results highlight the importance of soil- and leaf-P in defining the photosynthetic capacity of TMFs, with variations in N allocation and Rubisco activation state further influencing photosynthetic rates and N-use efficiency of these critically important forests. [ABSTRACT FROM AUTHOR]

The loss of biodiversity in transitional forests between the Cerrado and Amazonia, the two largest neotropical phytogeographic domains, is an issue of great concern. This extensive region is located within the ‘arc of deforestation’ zone where tropical forests are being lost at the fastest rate on the planet, but floristic diversity and variation among forests here is still poorly understood. We aimed to characterize the floristic composition of forests in this zone and explored the degree and drivers of differentiation within and across Araguaia and Xingu watersheds. In 10 sites we identified all trees with diameter ≥10 cm; these totaled 4944 individuals in 257 species, 107 genera and 52 families. We evaluated the data for multivariate variation using TWINSPAN and DCA to understand the species distribution among sites. There was a larger contribution from the Amazonian flora (169 species) than that of the Cerrado (109) to the transitional forests. Remarkably, 142 species (55%) were restricted to only one sampling site, while 29 species (>16%) are endemic to Brazil, suggesting potentially large loss of species and unique forest communities with the loss and fragmentation of large areas. Our results also suggest that watersheds may be a critical factor driving species distribution among forests in the Amazonian–Cerrado transition zone, and quantifying their role can provide powerful insight into devising better conservation strategies for the remaining forests. [ABSTRACT FROM AUTHOR]

We measured a diverse range of foliar characteristics in shrub and tree species in temperate rainforest communities along a soil chronosequence (six sites from 8 to 120 000 years) and used multilevel model analysis to attribute the proportion of variance for each trait into genetic (G, here meaning species-level), environmental (E) and residual error components. We hypothesised that differences in leaf traits would be driven primarily by changes in soil nutrient availability during ecosystem progression and retrogression. Several leaf structural, chemical and gas-exchange traits were more strongly driven by G than E effects. For leaf mass per unit area (MA), foliar [N], net CO2 assimilation and dark respiration rates and foliar carbohydrate concentration, the G component accounted for 60-87% of the total variance, with the variability associated with plot, the E effect, much less important. Other traits, such as foliar [P] and N: P, displayed strong E and residual effects. Analyses revealed significant reductions in the slopes of G-only bivariate relationships when compared with raw relationships, indicating that a large proportion of trait-trait relationships is species based, and not a response to environment per se. This should be accounted for when assessing the mechanistic basis for using such relationships in order to make predictions of responses of plants to short-term environmental change. [ABSTRACT FROM AUTHOR]

Photosynthesis/nutrient relationships of proximally growing forest and savanna trees were determined in an ecotonal region of Cameroon (Africa). Although area-based foliar N concentrations were typically lower for savanna trees, there was no difference in photosynthetic rates between the two vegetation formation types. Opposite to N, area-based P concentrations were-on average-slightly lower for forest trees; a dependency of photosynthetic characteristics on foliar P was only evident for savanna trees. Thus savanna trees use N more efficiently than their forest counterparts, but only in the presence of relatively high foliar P. Along with some other recent studies, these results suggest that both N and P are important modulators of woody tropical plant photosynthetic capacities, influencing photosynthetic metabolism in different ways that are also biome specific. Attempts to find simple unifying equations to describe woody tropical vegetation photosynthesis-nutrient relationships are likely to meet with failure, with ecophysiological distinctions between forest and savanna requiring acknowledgement. [ABSTRACT FROM AUTHOR]

Aim The accurate mapping of forest carbon stocks is essential for understanding the global carbon cycle, for assessing emissions from deforestation, and for rational land-use planning. Remote sensing ( RS) is currently the key tool for this purpose, but RS does not estimate vegetation biomass directly, and thus may miss significant spatial variations in forest structure. We test the stated accuracy of pantropical carbon maps using a large independent field dataset. Location Tropical forests of the Amazon basin. The permanent archive of the field plot data can be accessed at: Methods Two recent pantropical RS maps of vegetation carbon are compared to a unique ground-plot dataset, involving tree measurements in 413 large inventory plots located in nine countries. The RS maps were compared directly to field plots, and kriging of the field data was used to allow area-based comparisons. Results The two RS carbon maps fail to capture the main gradient in Amazon forest carbon detected using 413 ground plots, from the densely wooded tall forests of the north-east, to the light-wooded, shorter forests of the south-west. The differences between plots and RS maps far exceed the uncertainties given in these studies, with whole regions over- or under-estimated by > 25%, whereas regional uncertainties for the maps were reported to be < 5%. Main conclusions Pantropical biomass maps are widely used by governments and by projects aiming to reduce deforestation using carbon offsets, but may have significant regional biases. Carbon-mapping techniques must be revised to account for the known ecological variation in tree wood density and allometry to create maps suitable for carbon accounting. The use of single relationships between tree canopy height and above-ground biomass inevitably yields large, spatially correlated errors. This presents a significant challenge to both the forest conservation and remote sensing communities, because neither wood density nor species assemblages can be reliably mapped from space. [ABSTRACT FROM AUTHOR]

1. Tropical forest above-ground wood production (AGWP) varies substantially along environmental gradients. Some evidence suggests that AGWP may vary between regions and specifically that Asian forests have particularly high AGWP. However, comparisons across biogeographic regions using standardized methods are lacking, limiting our assessment of pan-tropical variation in AGWP and potential causes. 2. We sampled AGWP in NW Amazon (17 long-term forest plots) and N Borneo (11 plots), both with abundant year-round precipitation. Within each region, forests growing on a broad range of edaphic conditions were sampled using standardized soil and forest measurement techniques. 3. Plot-level AGWP was 49% greater in Borneo than in Amazonia (9.73 ± 0.56 vs. 6.53 ± 0.34 Mg dry mass ha-1 a-1, respectively; regional mean ± 1 SE). AGWP was positively associated with soil fertility (PCA axes, sum of bases and total P). After controlling for the edaphic environment,AGWP remained significantly higher in Bornean plots. Differences in AGWP were largely attributable to differing height-diameter allometry in the two regions and the abundance of large trees in Borneo. This may be explained, in part, by the greater solar radiation in Borneo compared with NWAmazonia. 4. Trees belonging to the dominant SE Asian family, Dipterocarpaceae, gained woody biomass faster than otherwise equivalent, neighbouring non-dipterocarps, implying that the exceptional production of Bornean forests may be driven by floristic elements. This dominant SE Asian family may partition biomass differently or be more efficient at harvesting resources and in converting themto woody biomass. 5. Synthesis. N Bornean forests have much greater AGWP rates than those in NW Amazon when soil conditions and rainfall are controlled for. Greater resource availability and the highly productive dipterocarps may, in combination, explain why Asian forests produce wood half as fast again as comparable forests in the Amazon. Our results also suggest that taxonomic groups differ in their fundamental ability to capture carbon and that different tropical regions may therefore have different carbon uptake capacities due to biogeographic history. [ABSTRACT FROM AUTHOR]

Background:Patterns in tropical forest nitrogen cycling are poorly understood. In particular, the extent to which leguminous trees in these forests fix nitrogen is unclear. Aims:We aimed to determine factors that explain variation in foliar δ15N (δ15NF) for Amazon forest trees, and to evaluate the extent to which putatively N2-fixing Fabaceae acquire nitrogen from the atmosphere. Methods:Upper-canopy δ15NFvalues were determined for 1255 trees sampled across 65 Amazon forest plots. Along with plot inventory data, differences in δ15NFbetween nodule-forming Fabaceae and other trees were used to estimate the extent of N2fixation. Results:δ15NFranged from −12.1‰ to +9.3‰. Most of this variation was attributable to site-specific conditions, with extractable soil phosphorus and dry-season precipitation having strong influences, suggesting a restricted availability of nitrogen on both young and old soils and/or at low precipitation. Fabaceae constituted fewer than 10% of the sampled trees, and only 36% were expressed fixers. We estimated an average Amazon forest symbiotic fixation rate of 3 kg N ha−1year−1. Conclusion:Plant δ15N indicate that low levels of nitrogen availability are only likely to influence Amazon forest function on immature or old weathered soils and/or where dry-season precipitation is low. Most Fabaceae species that are capable of nodulating do not fix nitrogen in Amazonia. [ABSTRACT FROM PUBLISHER]

Background:The zone of transition (ZOT) between the Cerrado and the Amazon forest in southern Amazonia represents a unique and rapidly shrinking area due to land-use change. Aims:To compare the dynamics and above-ground biomass of vegetation located in the ZOT with core Amazon forest and to determine how ZOT dynamics differ within vegetation types for different tree diameter classes. Methods:Censuses of trees were conducted in seven plots in monodominant forest, semi-deciduous seasonal forest, gallery forest, cerrado sensu stricto and cerradão, in north-eastern Mato Grosso, Brazil from 1996 to 2010, including data for the 2005 drought year. Separate analyses of stem dynamics and biomass were carried out for two different diameter (d) classes: 5 ≤d< 10 cm andd≥ 10 cm. Results:For trees withd≥ 10 cm the average mortality rate was 2.8% year−1, with an estimated above-ground dry biomass of 210 Mg ha−1. Trees with 5 ≤d< 10 cm constituted only a small fraction of the total biomass store (ca.10 Mg ha−1) and had a mortality rate of 7.4% year−1and recruitment of 6.5% year−1. Overall, mortality and recruitment in the ZOT were greater than in core Amazonian forests (1–2% year−1). Conclusions:The distinct vegetation formations of the southern Amazon ZOT are markedly more dynamic than core Amazonian forest. Continued long-term monitoring throughout the region is required to assess whether they also respond differently to climate change. [ABSTRACT FROM PUBLISHER]

Background:Lianas strongly influence tropical forest dynamics and diversity. Aims:To determine the relationship among richness, diversity, abundance and distribution of liana species in different vegetation formation types along a gradient within a savanna–forest transition zone in central Brazil. Methods:All liana species were identified and their girth measurements (≥5 cm) taken in one 1 ha plot at each of 15 sites that encompassed a range of vegetation types: dystrophic cerradão (tall closed woodland cerrado), gallery forest, flooded forest, semi-deciduous seasonal forest (one monodominant) and evergreen forest. We evaluated and compared the communities in terms of richness, community diversity (Shannon'sH’), equitability (Hurlbert's,PIE), and the distribution of liana abundance. Results:In total, 1467 individual lianas belonging to 65 species, 41 genera and 17 families were recorded in the 15 ha sampled. The value of H’ varied from 0–2.47, and that ofPIEranged from 0–0.90. While flooded forests had remarkably high liana densities, their liana community was dominated by just one species,Combretum laxum(64% of stems); the most abundant liana in non-flooded forests wasHeteropterys eglandulosa(13%). The different liana species showed varying affiliations with vegetation type, with distinct species groupings associated with the different vegetation types. Conclusions:Variations in species composition and distribution of lianas in this savanna–forest transition were found to be driven by environmental gradients that cause distinct species associations with discrete vegetation formation types. [ABSTRACT FROM PUBLISHER]

Background and aims: Our study quantified variations leaf respiration in darkness ( R) and light ( R), and associated traits along the Franz Josef Glacier soil development chronosequence in New Zealand. Methods: At six sites along the chronosequence (soil age: 6, 60, 150, 500, 12,000 and 120,000 years old), we measured rates of leaf R, R (using Kok method), light-saturated CO assimilation rates ( A), leaf mass per unit area ( M), and concentrations of leaf nitrogen ([N]), phosphorus ([P]), soluble sugars and starch. Results: The chronosequence was characterised by decreasing R, R and A, reduced [N] and [P] and increasing M as soil age increased. Light inhibition of R occurred across the chronosequence (mean inhibition = 16 %), resulting in ratios of R: A being lower than for R: A. Importantly, the degree of light inhibition differed across the chronosequence, being lowest at young sites and highest at old sites. This resulted in R: A ratios being relatively constant across the chronosequence, whereas R: A ratios increased with increasing soil age. Log-log R- A- M-[N] relationships remained constant along the chronosequence. By contrast, relationships linking rates of leaf R to [P] differed among leaves with low vs high [N]:[P] ratios. Slopes of log-log bivariate relationships linking R to A, M, [N] and [P] were steeper than that for R. Conclusions: Our findings have important implications for predictive models that seek to account for light inhibition of R, and for our understanding of how environmental gradients impact on leaf trait relationships [ABSTRACT FROM AUTHOR]