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Primary forests provide critical climate regulation functions through the capture and storage of carbon in biomass reservoirs. The capacity of primary forests to sustain biomass levels and the possible consequences of warming-induced increases in extreme disturbances are unresolved questions. We investigated the drivers of biomass accumulation in European primary mountain forests in the Carpathians. We used inventory datasets from a continental-scale survey of remnant primary forests to quantify levels of aboveground live and dead biomass across mixed beech and spruce forest types. We formulated nonlinear regression models to estimate the effects of abiotic and biotic factors, including plot-level disturbance history and tree age using dendrochronological methods. Our analyses show that biomass stocks are comparable with stocks present in other primary forests of temperate regions. Highest mean total biomass in mixed beech forests was in southern landscapes (491 ± 81 Mg ha−1) and western for spruce forests (388 ± 106 Mg ha−1). Forests maintained positive biomass accumulation rates over centuries-long time frames, mean plot-level age peaking at ~ 225 years. We demonstrate that primary forests continue to function as carbon sinks at older ages. Preserving the integrity of unmanaged forests serves as an important climate mitigation strategy. [ABSTRACT FROM AUTHOR]

Forests are critical for biodiversity conservation and climate change mitigation: reducing emissions, increasing removals, and providing resilient ecosystems with stable long‐term carbon storage. However, evaluating the mitigation effectiveness of forests managed for conservation versus commodity production has been long debated. We assessed factors influencing evaluation of mitigation effectiveness––land area, time horizon, reference level, carbon stock longevity––and tested the outcomes using analyses of carbon dynamics from an Australian ecosystem. Results showed that landscape scale accounting using carbon carrying capacity as the reference level and assessed over a series of time horizons best enables explicit evaluation of mitigation benefits. Time horizons need to differentiate between near‐term emissions reduction targets (2030 and 2050), relative longevity of carbon stocks in different reservoirs, and long‐term impacts on atmospheric CO2 concentration. Greatest mitigation benefits derive from conservation through continued forest growth (52% gain in carbon stock by 2050) and accumulating carbon to attain carbon retention potential (70% gain). Cumulative emissions from harvesting result in permanent elevation of atmospheric CO2 concentration (32 times the annual emission by rotation end). We recommend these time horizons and landscape scales for evaluating forest management to better guide policies and investments for achieving climate mitigation and biodiversity conservation. [ABSTRACT FROM AUTHOR]

Economics has long taken precedence over the environment in both governmental and business decision making, with the System of National Accounts and the indicator GDP coming to represent much that is wrong with the current environmental conditions. Increasing recognition of the environmental damage human activity causes and that human well-being depends on biodiversity and ecosystems means that new systems to measure and sustainably manage the world are needed. Integrating the environment into national accounts has been suggested as a way to improve information but so far impact on decision making is limited. This outlook needs to change. Using examples from Australia and Botswana, we show how integrating information on biodiversity, resource use and the economy via accounting can help create a new decision-making paradigm and enable a new policy framing with spending on biodiversity conservation and sustainability seen as an investment, not a cost. [ABSTRACT FROM AUTHOR]

Abstract: There are many popular treatments of Zen/Chan and Daoist themes related to working with horses; however, these works tend to be fairly superficial treatments of philosophical traditions. For deeper consideration of the philosophy of horse sports such as dressage, I explore themes and imagery in the Daodejing, such as noncontention, flow, humility, and mysticism that may help riders to unpack and enhance the experience of working with a nonhuman teammate. Comparative work, such as with Dewey's theory of aesthetic experience and the psychology of “flow,” further helps to conceptualize the relationship between athleticism and artistic value in formal equestrian sports. [ABSTRACT FROM AUTHOR]

Climate change mitigation benefits from the land sector are not being fully realised because of uncertainty and controversy about the role of native forest management. The dominant policy view, as stated in the IPCC’s Fifth Assessment Report, is that sustainable forest harvesting yielding wood products, generates the largest mitigation benefit. We demonstrate that changing native forest management from commercial harvesting to conservation can make an important contribution to mitigation. Conservation of native forests results in an immediate and substantial reduction in net emissions relative to a reference case of commercial harvesting. We calibrated models to simulate scenarios of native forest management for two Australian case studies: mixed-eucalypt in New South Wales and Mountain Ash in Victoria. Carbon stocks in the harvested forest included forest biomass, wood and paper products, waste in landfill, and bioenergy that substituted for fossil fuel energy. The conservation forest included forest biomass, and subtracted stocks for the foregone products that were substituted by non-wood products or plantation products. Total carbon stocks were lower in harvested forest than in conservation forest in both case studies over the 100-year simulation period. We tested a range of potential parameter values reported in the literature: none could increase the combined carbon stock in products, slash, landfill and substitution sufficiently to exceed the increase in carbon stock due to changing management of native forest to conservation. The key parameters determining carbon stock change under different forest management scenarios are those affecting accumulation of carbon in forest biomass, rather than parameters affecting transfers among wood products. This analysis helps prioritise mitigation activities to focus on maximising forest biomass. International forest-related policies, including negotiations under the UNFCCC, have failed to recognize fully the mitigation value of native forest conservation. Our analyses provide evidence for decision-making about the circumstances under which forest management provides mitigation benefits. [ABSTRACT FROM AUTHOR]

Carbon stock change due to forest management and disturbance must be accounted for in UNFCCC national inventory reports and for signatories to the Kyoto Protocol. Impacts of disturbance on greenhouse gas (GHG) inventories are important for many countries with large forest estates prone to wildfires. Our objective was to measure changes in carbon stocks due to short-term combustion and to simulate longer-term carbon stock dynamics resulting from redistribution among biomass components following wildfire. We studied the impacts of a wildfire in 2009 that burnt temperate forest of tall, wet eucalypts in south-eastern Australia. Biomass combusted ranged from 40 to 58 tC ha−1, which represented 6–7% and 9–14% in low- and high-severity fire, respectively, of the pre-fire total biomass carbon stock. Pre-fire total stock ranged from 400 to 1040 tC ha−1 depending on forest age and disturbance history. An estimated 3.9 TgC was emitted from the 2009 fire within the forest region, representing 8.5% of total biomass carbon stock across the landscape. Carbon losses from combustion were large over hours to days during the wildfire, but from an ecosystem dynamics perspective, the proportion of total carbon stock combusted was relatively small. Furthermore, more than half the stock losses from combustion were derived from biomass components with short lifetimes. Most biomass remained on-site, although redistributed from living to dead components. Decomposition of these components and new regeneration constituted the greatest changes in carbon stocks over ensuing decades. A critical issue for carbon accounting policy arises because the timeframes of ecological processes of carbon stock change are longer than the periods for reporting GHG inventories for national emissions reductions targets. Carbon accounts should be comprehensive of all stock changes, but reporting against targets should be based on human-induced changes in carbon stocks to incentivise mitigation activities. [ABSTRACT FROM AUTHOR]

Abstract: Greenhouse gas (GHG) inventories underpinning the United Nations Framework Convention on Climate Change (UNFCCC) and Kyoto Protocol report each country's net annual emissions, that is GHG flows. Yet the UNFCCC's goal is defined as a stock (atmospheric GHG concentration). Flow inventories are apt for the fossil fuel sector where flows are effectively one way, stock changes are almost entirely anthropogenic, and stocks are stable in the absence of human perturbation. For the land sector, flow-based GHG inventories obscure fundamental differences between ecosystems: in their carbon stock stability, restoration capacity, and density. This paper presents a national carbon accounting framework that is comprehensive and includes stocks as well as flows for reservoirs, lands and activities continuously over time. It complements current flow-based inventories under the UNFCCC and Kyoto Protocol. The framework differentiates reservoirs by their role in the global carbon cycle, distinguishing between geocarbon (carbon in the geosphere), biocarbon (carbon in the biosphere) and anthropogenic carbon (stockpiles, products and waste). A reservoir ranking system is proposed based on longevity, reversibility of carbon loss, and carbon density. This framework will support policy makers and researchers grappling with mitigation strategies and competing demands on agricultural land and natural ecosystems. [Copyright &y& Elsevier]

Evaluating contributions of forest ecosystems to climate change mitigation requires well-calibrated carbon cycle models with quantified baseline carbon stocks. An appropriate baseline for carbon accounting of natural forests at landscape scales is carbon carrying capacity (CCC); defined as the mass of carbon stored in an ecosystem under prevailing environmental conditions and natural disturbance regimes but excluding anthropogenic disturbance. Carbon models require empirical measurements for input and calibration, such as net primary production (NPP) and total ecosystem carbon stock (equivalent to CCC at equilibrium). We sought to improve model calibration by addressing three sources of errors that cause uncertainty in carbon accounting across heterogeneous landscapes: (1) data-model representation, (2) data-object representation, (3) up-scaling. We derived spatially explicit empirical models based on environmental variables across landscape scales to estimate NPP (based on a synthesis of global site data of NPP and gross primary productivity, n=27), and CCC (based on site data of carbon stocks in natural eucalypt forests of southeast Australia, n=284). The models significantly improved predictions, each accounting for 51% of the variance. Our methods to reduce uncertainty in baseline carbon stocks, such as using appropriate calibration data from sites with minimal human disturbance, measurements of large trees and incorporating environmental variability across the landscape, have generic application to other regions and ecosystem types. These analyses resulted in forest CCC in southeast Australia (mean total biomass of 360 t C ha−1, with cool moist temperate forests up to 1000 t C ha−1) that are larger than estimates from other national and international (average biome 202 t C ha−1) carbon accounting systems. Reducing uncertainty in estimates of carbon stocks in natural forests is important to allow accurate accounting for losses of carbon due to human activities and sequestration of carbon by forest growth. [ABSTRACT FROM AUTHOR]

From analysis of published global site biomass data (n = 136) from primary forests, we discovered (i) the world's highest known total biomass carbon density (living plus dead) of 1,867 tonnes carbon per ha (average value from 13 sites) occurs in Australian temperate moist Eucalyptus regnans forests, and (ii) average values of the global site biomass data were higher for sampled temperate moist forests (n = 44) than for sampled tropical (n = 36) and boreal (n = 52) forests (n is number of sites per forest biome). Spatially averaged Intergovern- mental Panel on Climate Change biome default values are lower than our average site values for temperate moist forests, because the temperate biome contains a diversity of forest ecosystem types that support a range of mature carbon stocks or have a long land-use history with reduced carbon stocks. We describe a framework for identifying forests important for carbon storage based on the factors that account for high biomass carbon densities, including (i) relatively cool temperatures and moderately high precipitation producing rates of fast growth but slow decomposition, and (ii) older forests that are often multiaged and multilayered and have experienced minimal human disturbance. Our results are relevant to negotiations under the United Nations Framework Convention on Climate Change regarding forest conservation, management, and restoration. Conserving forests with large stocks of biomass from deforestation and degradation avoids significant carbon emissions to the atmosphere, irrespective of the source country, and should be among allowable mitigation activities. Similarly, management that allows restoration of a forest's carbon sequestration potential also should be recognized. [ABSTRACT FROM AUTHOR]

The article provides information on the significance of George Herbert Mead's philosophies in relation to Chinese philosophy. It notes the importance of Mead's theory of the social self to Daoist views of human situatedness and ren, which is a Confucian ideal. Mead's concept of the self is also discussed along with details about his social behaviorism and elements of ren. Moreover, it presents morality in the context of Mead and Confucianism.

Abstract: This study examined the carbon budget of a Eucalyptus delegatensis forest over four years under contrasting weather conditions by using a comprehensive forest-growth model (CenW 3.1). Model parameterisation was constrained through multiple measurements, including daytime eddy flux measurements of CO2 and water vapour exchange, estimates of above- and below-ground biomass pools, growth rates measured through stem-diameter increments and measurement of specific ecosystem processes, such as litter fall and soil respiration rates. The resultant estimates of net ecosystem exchange ranged from an uptake of 4.0t Cha−1 year−1 in a year with adequate rainfall to a loss of 0.4t Cha−1 year−1 in a year affected by drought and insect damage. The simulations indicated that this reduction in carbon gain was primarily due to insect damage rather than a direct consequence of water shortage. Under good growing conditions, carbon gain accumulated equally in stem wood and other biomass pools while soil organic carbon and woody litter were gradually decreasing following harvesting that had occurred 20 years earlier. Under more stressful conditions, net biomass increments decreased, while soil organic carbon and woody litter increased because of greater litter inputs and because drier conditions inhibited decomposition. Modelled estimates of photosynthesis and net ecosystem exchange were similar to estimates from eddy flux observations alone provided that it used a novel routine for deriving night-time carbon fluxes. Estimates of net ecosystem exchange derived in the present work were, however, substantially lower than previous estimates that had been derived using a more traditional analysis of eddy flux data. This study showed that detailed physiological modelling is a valuable technique for combining all available site information as well as further constraints based on broader scientific principles and considerations of the conservation of mass. It can thus provide a powerful constraint on the overall site carbon budget of an ecosystem. [Copyright &y& Elsevier]

Books reviewed:Charlene Haddock Seigfried (ed.),Feminist Interpretations of John DeweyJane Duran,Worlds of Knowing: Global Feminist EpistemologiesJorge J. E. Gracia,Metaphysics and Its Tasks: The Search for the Categorical Foundation of Knowledge [ABSTRACT FROM AUTHOR]

• We propose an indicator development framework based on a systematic review, which: • Consists of 12 well-justified criteria linked to the steps in an expert process. • Distinguishes ecosystem characteristics and their indicators. • Is applicable in many fields of ecological/environmental/sustainability indicators. • Finally we identify two critical knowledge gaps for SEEA applications. The UN System of Environmental-Economic Accounting Ecosystem Accounting (SEEA EA) aims at regular and standardised stocktaking of the extent of ecosystems, their condition, and the services they provide to society. Recording the condition of ecosystems is one of the most complex pieces in this exercise and needs to be supported by consistent guidelines. SEEA EA defines the condition of an ecosystem as its overall quality, measured in terms of quantitative metrics describing its abiotic and biotic characteristics. One of the key challenges lies in identifying the most appropriate metrics for each ecosystem type that capture these essential characteristics. The objective of this paper is to create a well-defined framework for transparent and operative development of ecosystem condition indicators, which can be used in ecosystem accounting and ecosystem assessment studies. Starting from the SEEA EA documentation and a small targeted systematic review, we identified 12 key criteria, which we grouped according to their roles during the indicator development process. Five conceptual criteria (intrinsic relevance, instrumental relevance, sensitivity, directional meaning, and framework conformity) outline the priorities for identifying relevant characteristics of the ecosystems. Five practical criteria (validity, reliability, availability, simplicity, and compatibility) provide guidance on identifying concrete quantitative metrics for the selected characteristics. Finally, two ensemble criteria (comprehensiveness, and parsimony) ensure the completeness and complementarity of the final set of metrics. To tackle the climate and biodiversity crises, the condition of ecosystems needs to be better recognized in national economic planning. The proposed framework supports the selection of a concise set of salient and credible ecosystem condition indicators through a transparent, repeatable and scientific process. This can make the compilation of ecosystem condition accounts more accessible and more standardised on a global level, which is a key prerequisite for the success of SEEA EA. Additionally, the framework presented in this paper may be useful in other contexts where ecological, environmental, or sustainability indicators need to be identified. [ABSTRACT FROM AUTHOR]

Discusses the similarities between pragmatist and feminist ethics. Views of philosopher George Herbert Mead on the ethics of care; Relation of the feminist ethics of care with moral pluralism; Correlation of pragmatist and feminist ethics with social relationships.

Nature-based solutions (NbS) can address climate change, biodiversity loss, human well-being and their interactions in an integrated way. A major barrier to achieving this is the lack of comprehensiveness in current carbon accounting which has focused on flows rather than stocks of carbon and led to perverse outcomes. We propose a new comprehensive approach to carbon accounting based on the whole carbon cycle, covering both stocks and flows, and linking changes due to human activities with responses in the biosphere and atmosphere. We identify enhancements to accounting, namely; inclusion of all carbon reservoirs, changes in their condition and stability, disaggregated flows, and coverage of all land areas. This comprehensive approach recognises that both carbon stocks (as storage) and carbon flows (as sequestration) contribute to the ecosystem service of global climate regulation. In contrast, current ecosystem services measurement and accounting commonly use only carbon sequestration measured as net flows, while greenhouse gas inventories use flows from sources to sinks. This flow-based accounting has incentivised planting and maintaining young forests with high carbon uptake rates, resulting, perversely, in failing to reveal the greater mitigation benefit from protecting larger, more stable and resilient carbon stocks in natural forests. We demonstrate the benefits of carbon storage and sequestration for climate mitigation, in theory as ecosystem services within an ecosystem accounting framework, and in practice using field data that reveals differences in results between accounting for stocks or flows. Our proposed holistic and comprehensive carbon accounting makes transparent the benefits, trade-offs and shortcomings of NbS actions for climate mitigation and sustainability outcomes. Adopting this approach is imperative for revision of ecosystem accounting systems under the System of Environmental-Economic Accounting and contributing to evidence-based decision-making for international conventions on climate (UNFCCC), biodiversity (CBD) and sustainability (SDGs). Unlabelled Image • New approach for holistic and comprehensive accounting for carbon stocks and flows • Transparent information in accounts applied to evaluating nature-based solutions • Ecosystem service of climate regulation includes carbon storage and sequestration. • Prioritise protection of large, stable, resilient carbon stocks in natural forests • System of Environmental-Economic Accounting data informs climate change mitigation. [ABSTRACT FROM AUTHOR]

Natural and human disturbance along with climate change pose major challenges for resource management. This is relevant in natural forests, where conflict can occur between water provision and industrial logging. As a result, conversion of old forests to young, fast-growing stands through logging can dramatically reduce streamflow and water yield. We modelled changes in stream run-off and hence water yield from a forest catchment in response to clearcut logging and compared this with projected climate change (using a Representative Climate Futures [RCFs] approach). We focused on the Thomson Catchment, which is the largest single catchment for the city of Melbourne, south-eastern Australia. Within this catchment, we targeted our analysis at montane ash-type eucalypt forests, as these receive the most rainfall and are subject to clearcutting. We used several forest management scenarios to model changes in water yield over time. For our analysis of projected climate change, we employed a range of RCFs that represent 'consensus', 'wettest' and 'driest' scenarios to model the impacts of multiple Representative Concentration Pathways (RCPs). Our initial spatial analysis revealed that 42% of the ash-type eucalypt forests in the Thomson Catchment have been logged. Under historical and continued logging, stream runoff decreases by 40,211 ML by 2090 compared with a hypothetical baseline if logging had ceased in 1995 and 34,059 ML if logging continues beyond 2019. These losses exceed the projected impacts of climate change under the consensus and wettest scenarios, but the driest scenarios are projected to exceed these losses, consisting of 49,998 ML and 69,474 ML for RCP 4.5 and RCP 8.5, respectively. We suggest logging be excluded from the Thomson Catchment because of decreasing stream flows due to climate change and an increasing water demand due to human population growth. This study provides a quantitative approach for highlighting how resource conflicts can be magnified under climate change. Unlabelled Image • We quantified changes in water yields due to logging and projected climate change. • Widespread clearcut logging in water catchments reduces water yield. • Water loss from logging may exceed impacts under some climate change projections. • Water loss from logging may negate additional rainfall under optimistic projections. [ABSTRACT FROM AUTHOR]

The carbon stock in Europe's forests is decreasing and the importance of protecting "unmanaged" forests must be recognised in reversing this process. In order to keep carbon out of the atmosphere and to meet the Paris Agreement goals, the remaining primary forests must be protected and secondary forests should be allowed to continue growing to preserve existing carbon stocks and accumulate additional stocks. In order to reverse the decreasing forest carbon stocks in Europe (European Environmental Agency, 2019), the largest forest carbon stores must be protected and additional forests must be allowed to continue accumulating carbon (proforestation). [Extracted from the article]

With accelerating environmental change, understanding forest disturbance impacts on trade-offs between biodiversity and carbon dynamics is of high socio-economic importance. Most studies, however, have assessed immediate or short-term effects of disturbance, while long-term impacts remain poorly understood. Using a tree-ring-based approach, we analysed the effect of 250 years of disturbances on present-day biodiversity indicators and carbon dynamics in primary forests. Disturbance legacies spanning centuries shaped contemporary forest co-benefits and trade-offs, with contrasting, local-scale effects. Disturbances enhanced carbon sequestration, reaching maximum rates within a comparatively narrow post-disturbance window (up to 50 years). Concurrently, disturbance diminished aboveground carbon storage, which gradually returned to peak levels over centuries. Temporal patterns in biodiversity potential were bimodal; the first maximum coincided with the short-term post-disturbance carbon sequestration peak, and the second occurred during periods of maximum carbon storage in complex old-growth forest. Despite fluctuating local-scale trade-offs, forest biodiversity and carbon storage remained stable across the broader study region, and our data support a positive relationship between carbon stocks and biodiversity potential. These findings underscore the interdependencies of forest processes, and highlight the necessity of large-scale conservation programmes to effectively promote both biodiversity and long-term carbon storage, particularly given the accelerating global biodiversity and climate crises. [ABSTRACT FROM AUTHOR]

Since 2009, the Canadian and Alberta governments have been developing monitoring plans for surface water quality and quantity of the lower Athabasca River and its tributaries (2010–2013). The objectives of the present study to the fish monitoring program were to 1) assess the current status of fish in a tributary of the lower Athabasca River, 2) identify existing differences between upstream reference and within the oil sands deposit exposure sites, and 3) identify trends/changes in fish performance indicators relative to historical studies. The present study examines the fish performance indicators in slimy sculpin (Cottus cognatus) in the Steepbank River, Alberta, in terms of growth, gonad size, condition, and hepatic 7‐ethoxyresorufin‐O‐deethylase (EROD) activity as an indicator of exposure to oil‐sands‐related compounds. The sampling program followed historical sampling methods (1999–2000) to provide comparable data over time with an additional upstream site (n = 2) added as development progressed. Consistent changes were documented in sculpin collected from downstream sections of the Steepbank River within the oil sands deposit (n = 2) in 2010 through 2013. Sculpin demonstrated increased liver size with corresponding induction of EROD activity consistent with historical data and reductions in energy investment relative to reproductive development and gonadal steroid production capacity. There was no consistent evidence of changes in fish performance indicators with increased surface mining development, particularly adjacent to the Steepbank River Mid site. Although physical development in the Steepbank watershed has increased over the last 15 yr, these results are consistent with historical data suggesting that the magnitude of the response in the aquatic environment adjacent to the development has not changed. Environ Toxicol Chem 2020;39:396–409. © 2019 SETAC [ABSTRACT FROM AUTHOR]

Biodiversity conservation is a global imperative, and many national and international actions aim to halt and reverse biodiversity decline. This study tests how ecosystem accounting, as standardised in the System of Environmental-Economic Accounting, could be used to integrate ecological and economic (e.g. environmental protection expenditure) data needed for biodiversity conservation using the example of the critically endangered Box-gum grassy woodlands (dominated by Eucalyptus spp.) in Australia. Despite data limitations, ecosystem extent accounts were produced and indicated that the likely extent of Box-gum grassy woodlands increased by 54,000 ha or 1.5 % over 16 years to 3.5 million ha in 2017. However, the possible extent decreased by more than one million ha, reflecting uncertainty in the estimate and the limitations of remotely-sensed information for estimating ecosystem extent. There was large regional variation in the changes, and the reasons for change, which are allocated to anthropogenic and natural changes in accounting, were not identified owing to a lack of information. As such, we could not determine if illegal activities or the ecosystem's recovery plan had any effect. This study showed that ecosystem accounting has the potential to assist biodiversity conservation by providing information that could support adaptive management by, for example, evaluating the causes of changes in the extent of threatened ecosystems and applying this learning to guide the allocation of resources to more effective conversation interventions. To achieve this potential, better data and regular and standardised reporting are needed, which will require cooperation between all agencies involved in biodiversity conservation. [Display omitted] • Biodiversity conservation can be assisted by ecosystem accounting. • Partial ecosystem accounts can be built with available environmental information. • Data limitations mean the potential of ecosystem accounting is yet to be realised. • Accounts for Box-Gum Grassy Woodlands show little change in the area between 2001 and 2017. • Land management data are a gap for Box gum grassy woodlands conservation evaluation. [ABSTRACT FROM AUTHOR]

Abstract: Eddy covariance measurements often underestimate the net exchange of CO2 between forest canopies and the atmosphere under stable atmospheric conditions, when horizontal and vertical advection are significant. A novel experimental design was used to measure all terms in the mass balance of CO2 in a 50m×50m wide, 6m tall control volume (CV) located on the floor of a 40m tall Eucalyptus forest to examine the contributions of the eddy flux, the change in storage and the horizontal and vertical advection terms. Horizontal flux divergences between the four vertical walls of the CV were determined using perforated tubing arranged parallel to the ground to measure CO2 mixing ratios. The change in storage was calculated using CO2 concentration profiles measured in the centre of the CV. Vertical advection was calculated using these profiles, combined with vertical velocities, , calculated using the mass continuity equation and horizontal velocities measured at the mid-point of each wall of the CV. Vertical and horizontal advection and the eddy flux terms all contributed significantly to the mass balance of the CV at night, while the eddy flux term was dominant and negative for a short period around noon when photosynthesis exceeded respiration. Large vertical gradients of CO2 at night cause estimates of vertical advection to be extremely sensitive to small errors in with standard errors of the mean flux exceeding 3μmolCO2 m−2 s−1. Vertical velocities need be measured to an accuracy better than 1mms−1 to minimize errors in vertical advection when vertical gradients of CO2 ratios are very large at night. Calculated horizontal advection is sensitive to errors in the wind vectors through the faces of the CV when horizontal concentrations gradients are large. Errors in eddy fluxes and change in storage are smaller than for the advection terms and errors for all components are smaller during the day than at night. [Copyright &y& Elsevier]

Abstract: Even moderately complex topography can lead to significant horizontal and vertical advection and a consequent underestimation of nocturnal CO2 effluxes derived from eddy covariance measurements on a single tower. The standard approach to select nighttime eddy flux data uses a threshold in friction velocity to exclude periods when advection is important but this is problematic in situations where turbulence is intermittent. van Gorsel et al. [van Gorsel, E., Leuning, R., Cleugh, H.A., Keith, H., Suni, T., 2007. Nocturnal carbon efflux: reconciliation of eddy covariance and chamber measurements using an alternative to the u *-threshold filtering technique. Tellus 59B, 397–403] have developed an alternative method that estimates the CO2 flux from the maximum of the eddy flux plus change in storage term in the period after sunset when stable stratification develops. During this time the advection terms do not contribute significantly to the mass balance of the air layer below the eddy flux instruments at the Tumbarumba flux station (SE Australia). Advection dominates only later in the night, following the development of large horizontal and vertical gradients of CO2. As net nighttime and daytime fluxes are often of similar magnitude but opposite in sign, underestimation of respiration can lead to large errors in annual ecosystem carbon budgets. Nocturnal respiration rates obtained using the new approach are systematically higher compared to previously published results that used a u * -threshold filter, and are in excellent agreement with independent chamber measurements. Revised net ecosystem exchange (NEE) calculations are therefore substantially reduced compared to those previously published (differing by 5.6±0.5tCha−1 year−1 based on a 34-month period) and compare well with results from an ecosystem model (differing by −0.2±0.7tCha−1 year−1 based on the same time period). Due to a drought period in 2003 and a subsequent insect attack NEE at Tumbarumba has been highly variable. Within 5 years the forest changed from being a carbon sink of −7.5tCha−1 year−1 to a source of +2.3tCha−1 year−1. This high variability demonstrates the importance of long-term, high-resolution time series when interpreting ecosystem data. The study further confirms the importance of using multiple measurement techniques and modelling to improve confidence in the mutually constrained NEE values. [Copyright &y& Elsevier]

Abstract: An analytical method for calculating the sub-diurnal change in heat storage in tree trunks is presented and incorporated in a soil vegetation atmosphere transfer (SVAT) model. The modelled change in biomass heat storage (J tr) is driven by radial heat diffusion within the trunks and surface heat exchange by convection, insolation and longwave radiation. The calculation requires only variables from the previous and current time step and is independent of measured biomass temperature. The model was applied to a 40m tall Australian temperate Eucalyptus forest at the Tumbarumba Ozflux site. A comparison between modelled and measured trunk temperatures showed agreement to within 1°C, providing confidence in the model. Hourly values of J tr peaked at 61Wm−2 for this site. Similar values of J tr were obtained using an adaptation of the force-restore method. Additional calculations for a range of leaf area indices and trunk radii enable a quick estimate of the maximum hourly value of J tr for any forest with given leaf area index, quadratic mean trunk radius (at breast height) and biomass. Inclusion of heat storage fluxes in the hourly available energy budget for the forest improved agreement between available energy and measured heat fluxes above the canopy, with energy closure rising from 90 to 101%. Accounting for J tr in the SVAT model also improved agreement between measured and modelled fluxes of sensible and latent heat. [Copyright &y& Elsevier]

We tested the ability of a model to scale gas exchange from leaf level to whole-tree level by: (1) measuring leaf gas exchange in the canopy of 10 trees in a tall Eucalyptus delegatensis RT Baker forest in NSW, Australia; (2) monitoring sap flow of the same 10 trees during the measurement week; and (3) using an individual-tree-based model (MAESTRA) to link the two sets of measurements. Photosynthesis and stomatal conductance components of the model were parameterized with the leaf gas exchange data, and canopy structure was parameterized with crown heights, dimensions and leaf areas of each of the measurement trees and up to 45 neighboring trees. Transpiration of the measurement trees was predicted by the model and compared with sap flow data. Leaf gas exchange parameters were similar for all 10 trees, with the exception of two smaller trees that had relatively low stomatal conductances. We hypothesize that these trees may have experienced water stress as a result of competition from large neighboring trees. The model performed well, and in most cases, was able to replicate the time course of tree transpiration. Maximum rates of transpiration were higher than measured rates for some trees and lower than measured rates for others, which may have been a result of inaccuracy in estimating tree leaf area. There was a small lag (about 15-30 minutes) between sap flow and modeled transpiration for some trees in the morning, likely associated with use of water stored in stems. The model also captured patterns of variation in sap flow among trees. Overall, the study confirms the ability of models to estimate forest canopy transpiration from leaf-level measurements. [ABSTRACT FROM AUTHOR]

Micrometeorological measurements made on single towers often underestimate nighttime respiration of terrestrial ecosystems because they cannot account for vertical and horizontal advection, thereby causing systematic errors in estimates of net ecosystem carbon exchange. We show that there is a maximum in the sum of the turbulent flux and change in storage of CO2 in the early evening, Rmax, that is in close agreement with concurrent and independent estimates of net carbon exchange from soil and plant chambers. We hypothesize that the peak occurs because there is a time delay between the onset of radiative cooling and the development of temperature gradients that are strong enough to initiate thermally-driven horizontal and vertical flows that remove the stored CO2. We propose taking advantage of this time delay to develop relationships between Rmax and soil temperature and moisture. The new parameterization leads to realistic values of nighttime respiration, and therefore to improved estimates of net ecosystem exchange. [ABSTRACT FROM AUTHOR]