Mean Annual Production Research Articles

Socio-economic contributions of small-scale plantations in Ethiopia

In order to enhance the attention given by farmers, government and concerned bodies, the socio-economic contributions of small-scale plantations should be studied. This study identified the socio-economic benefits of small-scale plantations in the Godera Woreda of Gambella Region, Ethiopia. Data were collected through questioners and key informant interviews from 208 farmers and 8 key informants. Descriptive statistics and a regression model were used to analyse the data. The results of the study revealed that of the average 1.72 ha of land possessed by small-scale farmers 0.81 ha was used for tree plantations. The main types of plantations were coffee, eucalyptus, banana and avocado. The mean annual production was 645 kg, 290 kg and 271 kg for coffee, banana and avocado, respectively. Small-scale farmers earned a mean of 4675.56 Birr from plantations which was 32.37 % of the total income. The Woreda government gained 365,022 Birr royalty payment during 2015/16.The regression results show income from plantations significantly affects the annual income of small-scale farmers (β = 0.436, p < 0.01). Access to basic services, land use change, expenditures, population growth, employment opportunities, and migration are social changes supported by small-scale plantations. The availability of a favourable environment, extension service, land, and peace are opportunities of plantations. In contrast, challenges of small-scale plantations are disease, low prices for product, lack of improved plantation varieties, shortage of land, lack of demand, climate change and rainfall reduction, lack of government support, and high transportation costs. It is recommended to strengthen the small-scale plantations for better positive socio-economic contributions of the sector through supporting the opportunities and management of identified challenges.

An Evaluation of Historical Trends in New Mexico Beef Cattle Production in Relation to Climate and Energy

In support of Food-Energy-Water Systems (FEWS) analysis to enhance its sustainability for New Mexico (NM), this study evaluated observed trends in beef cattle population in response to environmental and economic changes. The specific goal was to provide an improved understanding of the behavior of NM’s beef cattle production systems relative to precipitation, temperature, rangeland conditions, production of hay and crude oil, and prices of hay and crude oil. Historical data of all variables were available for the 1973–2017 period. The analysis was conducted using generalized autoregressive conditional heteroscedasticity models. The results indicated declining trends in beef cattle population and prices. The most important predictors of beef cattle population variation were hay production, mean annual hay prices, and mean annual temperature, whereas mean annual temperature, cattle feed sold, and crude oil production were the most important predictors for calf population that weigh under 500 lb. Prices of beef cattle showed a strong positive relationship with crude oil production, mean annual hay prices, rangeland conditions, and mean annual precipitation. However, mean annual temperature had a negative relationship with mean annual beef prices. Variation in mean annual calf prices was explained by hay production, mean annual temperature, and crude oil production. This analysis suggested that NM’s beef cattle production systems were affected mainly and directly by mean annual temperature and crude oil production, and to a lesser extent by other factors studied in this research.

Structural and functional characterization of the dry forest in central Argentine Chaco

Here, we studied the composition, structure and functioning of the woody vegetation of a 1000-ha area of the Central Argentine Chaco. First, we identified, through Landsat satellite image processing, three different vegetation classes: two forest types and a savanna. Each class was field surveyed to analyze the composition and structure of the woody plant community. Functioning was assessed through the enhanced vegetation index – a proxy of productivity – obtained from the MODIS sensor. The forest classes showed no differences in composition but some differences in structural attributes, particularly in the density of the dominant tree species in the area, Aspidosperma quebracho-blanco. As expected, the savanna showed less density and basal area of woody plants, with a relative high proportion of tree species seedlings and heliophilous shrubs. The forest class with less density of A. quebracho-blanco presented higher productivity. This could be related to a higher ability of the shrub layer to intercept radiation because shrubs are under an open canopy, as has been noted for early successional stages. Additionally, we found that annual mean productivity for the three classes showed a negative trend in the period 2000-2014. Our results provide valuable information since there are no studies addressing relationships between structural and functional attributes at local level in the Chaco Region.

Sensitivity of ocean biogeochemistry to the iron supply from the Antarctic Ice Sheet explored with a biogeochemical model

Abstract. Iron (Fe) delivery by the Antarctic Ice Sheet (AIS) through ice shelf and iceberg melting enhances primary productivity in the largely iron-limited Southern Ocean (SO). To explore this fertilization capacity, we implement a simple representation of the AIS iron source in the global ocean biogeochemical model NEMO-PISCES. We evaluate the response of Fe, surface chlorophyll, primary production, and carbon (C) export to the magnitude and hypothesized vertical distributions of the AIS Fe fluxes. Surface Fe and chlorophyll concentrations are increased up to 24 % and 12 %, respectively, over the whole SO. The AIS Fe delivery is found to have a relatively modest impact on SO primary production and C export, which are increased by 0.063±0.036 PgC yr−1 and 0.028±0.016, respectively. However, in highly fertilized areas, primary production and C export can be increased by up to 30 % and 42 %, respectively. Icebergs are predicted to have a much larger impact on Fe, surface chlorophyll, and primary productivity than ice shelves in the SO. The response of surface Fe and chlorophyll is maximum in the Atlantic sector, northeast of the tip of the Antarctic Peninsula, and along the East Antarctic coast. The iceberg Fe delivery below the mixed layer may, depending on its assumed vertical distribution, fuel a non-negligible subsurface reservoir of Fe. The AIS Fe supply is effective all year round. The seasonal variations of the iceberg Fe fluxes have regional impacts that are small for annual mean primary productivity and C export at the scale of the SO.

The Carbon Balance of the Southeastern U.S. Forest Sector as Driven by Recent Disturbance Trends

AbstractThis study documents annual carbon stocks and fluxes from 1986 to 2010 at 30‐m resolution across southeastern U.S. forests, analyzing trends and regional greenhouse gas exchange. We used forest inventory data to guide a carbon cycle model representing postdisturbance carbon dynamics for diverse forest and site conditions. We mapped carbon stocks and fluxes with stand age inferred from spaceborne disturbance monitoring and biomass. We assessed the fate of harvested biomass with a wood products model. We found that pine forests experienced the largest biomass removals, with paper products leading all end‐uses. Averaging across all SE forestlands, mean annual net ecosystem productivity decreased from 116 gC · m−2 · year−1 in 1986 to 71 gC · m−2 · year−1 in 2007, and 85 gC · m−2 · year−1 in 2010, equating to a range of 25 to 41 Tg C/year (mean of 34 Tg C/year). Interannual variability in forest‐atmosphere carbon exchange is dominated by the extent of harvesting, with removals ranging from 23 to 56 Tg C/year. Region‐wide live biomass stocks varied little over time, averaging 5.0 kg C/m2 for aboveground biomass or 1,780 TgC, with average annual biomass growth balanced by harvest removals. However, net biome productivity exhibited large interannual variability, spanning a sink of 16 Tg C/year in 1986 to a source of −30 Tg C/year in the year of peak harvest. Two thirds of harvest removals are emitted within 50 years, 8% as methane, causing the forest sector to act as a large CO2‐equivalent source. Uncertainties are estimated at ± 25%.

Epidemiological factors and mitigation measures influencing production losses in cattle due to bovine viral diarrhoea virus infection: A meta-analysis.

Infection with bovine viral diarrhoea virus (BVDV) is associated with a loss in productivity in cattle farms. Determining which factors influence monetary losses due to BVDV could facilitate the implementation of mitigation measures to reduce the burden of BVDV. Mixed‐effect meta‐analysis models were performed to estimate the extent to which the costs of mean annual BVDV production losses per animal may be influenced by epidemiological factors such as BVDV introduction risk, initial prevalence, viral circulation intensity and circulation duration (trial 1). Additionally, changes in mean annual BVDV production losses per animal due to specific mitigation measures (i.e., biosecurity, vaccination, testing and culling, cattle introduction or contact with neighbouring cattle herds) were analysed (trial 2). In total, 19 studies were included in the meta‐analysis to assess mean annual BVDV production losses. The mean annual direct losses were determined to be €42.14 per animal (trial 1). The multivariate meta‐regression showed that four of the previously mentioned epidemiological factors significantly influenced the mean annual BVDV production losses per animal. Indeed, the per animal costs increased to €67.19 when these four factors (trial 1) were considered as “high or moderate” compared to “low”. The meta‐regression analysis revealed that implementation of vaccination and biosecurity measures were associated with an 8%–12% and 28%–29% decrease in BVDV production losses on average, respectively, when simulated herds were compared with or without such mitigation measures (trial 2). This reduction of mean annual BVDV production losses per animal due to mitigation measures was partially counteracted when farmers brought new cattle on to farm or allowed contact with neighbouring cattle herds. The influencing mitigation factors presented here could help to guide farmers in their decision to implement mitigation strategies for the control of BVDV at farm level.

Pervasively high mangrove productivity in a major tropical delta throughout an ENSO cycle (Southern Caribbean, Colombia)

Rhizophora mangle is a mangrove forest foundation species that can create vegetated habitat, support entire animal and plant communities, and modulate ecosystem processes. Changes in freshwater subsidies over space and time may alter the performance of mangrove foundation species, presumably resulting in disproportionally large effects on energy flow. Yet the linkages between above-ground biomass and below-ground carbon reservoirs across freshwater-subsidy gradients remain poorly understood in many regions. We assessed the dynamics of litterfall production and breakdown of leaf material in a monospecific Rhizophora mangle forest thriving in a small bay in the Atrato River Delta (Southern Caribbean coast of Colombia), during a major El Niño to La Niña transition (from July 2015 to October 2016). Although parameters varied at different spatial scales within the bay, the mean annual total litter production (55 ± 15 g m−2 day−1 or 20 ± 5 Mg ha−1 yr−1) and the mean mass loss of leaf litter (1.0% and 1.7% day−1, above- and below-ground, respectively) are the highest reported for R. mangle-dominated forests worldwide. Total litter production and mass loss rates did not vary significantly over time. The lack of temporal effect was counterintuitive, because these rates typically show strong seasonal variation in mangroves elsewhere in the tropics. We concluded that mangroves in this area constitute a primary productivity hotspot (leaf fall carbon spatio-temporal range: 0.81–1.30 g C m−2 d−1). Based on a comparison of our results and data from the literature, we hypothesize that high freshwater input from the Atrato River subsidizes mangrove plants settled on the deltaic front, which sustain pervasively high litterfall rates. The high mass loss rates of leaf litter observed in this study demonstrate the importance of carbon vertical fluxes across the forest floor in fringing mangroves for carbon sinking.

Mercado interestadual de carvão vegetal no estado do Tocantins

A produção de carvão vegetal proveniente das florestas nativas tem pressionado os biomas em especial o Cerrado, cuja devastação da vegetação tem mantido carvoarias com destino para as siderúrgicas brasileiras. A reposição florestal é uma ferramenta de gestão ambiental utilizada para diminuir a pressão sobre os recursos naturais por meio do reflorestamento. Dados da produção de carvão vegetal permitem estipular a quantidade de créditos de reposição florestal original, para compensar a utilização dos recursos naturais. O objetivo com este trabalho foi apresentar o panorama atual da produção e dos principais consumidores e destinos de carvão vegetal proveniente de floresta nativa do estado do Tocantins. Como fonte de dados utilizou-se os Documentos de Origem Florestal cedidos pelo Instituto Brasileiro do Meio Ambiente e dos Recursos Naturais Renováveis (IBAMA) durante os anos de 2009 a 2016. Com os dados dispostos em planilha eletrônica, aplicou-se a estatística descritiva. Para a conversão da quantidade de carvão produzido em áreas de florestas plantadas, originadas da reposição florestal, adotou-se os valores estipulados na Resolução nº. 28, de 22 de novembro de 2011, do Conselho Estadual do Meio Ambiente do Tocantins (COEMA-TO). Conclui-se que o estado do Tocantins apresentou um cenário de constante crescimento da produção de carvão vegetal nativo, com uma produção média anual de 2009 a 2013 de 546.071,3 metros de carvão, diminuindo para 145.128 m de 2014 a 2016, tendo como principal consumidor o estado de Minas Gerais, que consumiu 77,01% de sua produção no período de 2009 a 2016.

Social-Ecological Functional Types: Connecting People and Ecosystems in the Argentine Chaco

Sustainability science recognizes the importance of the integrated assessment of the ecological and social systems in land-use planning. However, most studies so far have been conceptual rather than empirical. We developed a framework to characterize the social-ecological systems heterogeneity according to its functioning through the identification of social–ecological functional types (SEFT). The SEFT framework builds on the plant, ecosystem and agent functional type approaches, taking a step forward to integrate the dimensions of social–ecological systems into an operational product to characterize administrative units in a hierarchical way. To illustrate this novel framework, we described the heterogeneity of SEFT in the Argentine Chaco by clustering administrative entities. This area is a global deforestation hotspot and has diverse social actors that harness ecosystem services in multiple, and sometimes contrasting and conflictive, ways which determines an urgent need for land-use planning. We combined data from national census and remote sensing to identify SEFT by clustering census tracts based on 17 input variables that integrate key human, ecological and interaction processes across landscapes. We identified three classes and eight subclasses of SEFT. Ecological variables defined the first level of heterogeneity (classes), while human variables and the variables of interactions between the human and ecological components defined a second level of heterogeneity (subclasses). The degree of anthropization and mean annual productivity were important variables to explain the first two axes in the ordination (32% of the total variance). This framework offers a conceptually novel and comprehensive approach to understand the spatial heterogeneity of social–ecological systems functioning, which could play a pivotal role to support conservation or land-use planning in rural areas.

Water and carbon dioxide exchange of an alpine meadow ecosystem in the northeastern Tibetan Plateau is energy-limited

The alpine meadow in the Tibetan Plateau (TP) is a fragile ecosystem and very sensitive to climate change and human activities. However, the flux (energy, water, and carbon dioxide) exchanges (FEs) and their controls in this ecosystem are not well understood. Using two years (2015–2016) of observations from three eddy covariance towers and different grazing management types, we quantified the FEs of an alpine meadow ecosystem in the northeastern TP. A boosted regression trees (BRT)-based method was used to determine the environmental controls of FEs and clarify the factors causing the differences in FEs among the sites. The mean annual latent heat flux (LE), sensible heat flux (H), and evapotranspiration (ET) of the sites were 36.3 W m−2, 23.2 W m−2, and 458.2 mm, respectively. The mean annual gross primary productivity (GPP) and ecosystem respiration (Re) of the sites were 504.8 and 317.2 g C m−2, respectively. The mean annual net ecosystem CO2 exchange (NEE) of the sites was –187.6 g C m–2, indicating that the ecosystem was a CO2 sink, not accounting for grazing losses. The BRT-based analysis showed that, (i) The LE (ET) and H were mostly determined by soil temperature (ST) and downward shortwave radiation (DR), while the NEE, GPP, and Re were primarily correlated with ST. As a result, the FEs of the ecosystem were energy-limited; (ii) The high spatial heterogeneity in multiple environmental variables jointly determined the differences in FEs of the ecosystem. The differences in LE (ET) and H among the sites resulted from multiple environmental variables, including DR, ST, precipitation, and SM; and differences in NEE, GPP, and Re were mainly caused by precipitation, SM, and RH. The study highlights that future warming will enhance GPP and Re of the ecosystem, while reducing the CO2 sink because of the larger increases in Re than in GPP.

Changes in productivity and carbon storage of grasslands in China under future global warming scenarios of 1.5°C and 2°C

Abstract Aims The impacts of future global warming of 1.5°C and 2°C on the productivity and carbon (C) storage of grasslands in China are not clear yet, although grasslands in China support ~45 million agricultural populations and more than 238 million livestock populations, and are sensitive to global warming. Methods This study used a process-based terrestrial ecosystem model named ORCHIDEE to simulate C cycle of alpine meadows and temperate grasslands in China. This model was driven by high-resolution (0.5° × 0.5°) climate of global specific warming levels (SWL) of 1.5°C and 2°C (warmer than pre-industrial level), which is downscaled by EC-EARTH3-HR v3.1 with sea surface temperature and sea-ice concentration as boundary conditions from IPSL-CM5-LR (low spatial resolution, 2.5° × 1.5°) Earth system model (ESM). Important Findings Compared with baseline (1971–2005), the mean annual air temperature over Chinese grasslands increased by 2.5°C and 3.7°C under SWL1.5 and SWL2, respectively. The increase in temperature in the alpine meadow was higher than that in the temperate grassland under both SWL1.5 and SWL2. Precipitation was also shown an increasing trend under SWL2 over most of the Chinese grasslands. Strong increases in gross primary productivity (GPP) were simulated in the Chinese grasslands, and the mean annual GPP (GPPMA) increased by 19.32% and 43.62% under SWL1.5 and SWL2, respectively. The C storage increased by 0.64 Pg C and 1.37 Pg C under SWL1.5 and SWL2 for 50 years simulations. The GPPMA was 0.670.390.88 (0.82) (model meanminmax (this study)), 0.850.451.24 (0.97) and 0.940.611.30 (1.17) Pg C year−1 under baseline, SWL1.5 and SWL2 modeled by four CMIP5 ESMs (phase 5 of the Coupled Model Inter-comparison Project Earth System Models). In contrast, the mean annual net biome productivity was −18.55−40.374.47 (−3.61),18.65−2.0364.03 (10.29) and 24.158.3838.77 (24.93) Tg C year−1 under baseline, SWL1.5 and SWL2 modeled by the four CMIP5 ESMs. Our results indicated that the Chinese grasslands would have higher productivity than the baseline and can mitigate climate change through increased C sequestration under future global warming of 1.5°C and 2°C with the increase of precipitation and the global increase of atmospheric CO2 concentration.

Determination of the Natural Host Status of Avocado Fruit to Pestiferous Thrips (Thysanoptera: Thripidae) in KwaZulu-Natal, South Africa

The South African avocado industry is export-oriented, with approximately 3.0 % of international market share and with a five-year mean annual production of 118 000 t from 17 500 ha. Feeding by thrips results in fruit scarring and corky tissue development, making the fruit unsuitable for export. The study aimed to identify the spectrum of thrips in avocado flowers and more importantly, to confirm the identity of the thrips species responsible for damaging fruit. Thrips were collected from flowering panicles and identified using taxonomic keys. Frankliniella occidentalis (Pergande), Scirtothrips aurantii (Faure), Thrips gowdeyi (Bagnall), Thrips pusillus (Bagnall), Thrips tenellus (Trybom), Haplothrips gowdeyi (Franklin), Haplothrips bedfordi (Jacot-Guillarmod) and Megalurothrips sjostedti (Trybom) were consistently collected from May to September 2018. The minute size of thrips warranted a pre-season trial to determine the best netting material to contain thrips. Insect screen (149 µm), nylon netting (250 µm), chiffon (210 µm), voile (250 µm), organza (500 µm), tea filter paper (74 µm) and coffee filter paper (53 µm) were evaluated. The experiment was laid out as a randomised complete block design with six replications and the trials repeated twice. Only coffee filter paper and tea filter paper contained at least 85 % of the thrips and were therefore chosen for thrips exclusion trials. Surveillance by fruit sampling was undertaken to determine the natural host status of avocado to thrips. Avocado fruitlets were randomly sampled and incubated under laboratory conditions. Scirtothrips aurantii (Faure) (the South African citrus thrips) emerged from fruitlets and was sustained on that fruit to adulthood. This is the first study to demonstrate that avocado is a natural host to this pest in South Africa.

Sensitivity of Labrador Sea Water Formation to Changes in Model Resolution, Atmospheric Forcing, and Freshwater Input

AbstractLabrador Sea Water (LSW) is one of the main contributors to the lower limb of the Atlantic Meridional Overturning Circulation. In this study, we explore the sensitivity of LSW formation to model resolution, Greenland melt, absence of high‐frequency atmospheric phenomena, and changes in precipitation. We use five numerical model simulations at both (1/4)° and (1/12)° resolutions. A kinematic subduction approach is used to obtain the LSW formation rate over the period 2004 to 2016. The control simulation, with (1/4)° resolution, showed a mean annual production rate of 1.9 Sv (1 Sv = 106 m3/s) in the density range of 27.68–27.80 kg/m3 for the period 2004–2016. Deep convection events that occurred during 2008, 2012, and 2014–2016 were captured. We found that with (1/4)° resolution the LSW formation rate is 19% larger compared with its counterpart at (1/12)° resolution. The presence of Greenland melt and an increase in the precipitation impact the denser LSW layer replenishment but do not decrease the overall LSW formation rate nor the maximum convection depth. A dramatic response was found when filtering the atmospheric forcing, which induced a decrease of 44% in heat loss over the Labrador Sea, strong enough to halt the deep convection and decrease the LSW formation rate by 89%. Even if our experiment was extreme, a decrease in the storms crossing the Labrador Sea with a consequent reduction in the winter heat loss might be a bigger threat to deep convection and LSW formation in the future than the expected increases in the freshwater input.

Transformation from natural to wheat ecosystems enhances fine roots production and soil organic carbon input in an arid region

In arid regions, fine roots turnover contributes directly to soil carbon and nutrient cycling. However, less information is available on how increasing agricultural activities influence those dynamics. Fine roots biomass, production, and turnover rate were measured by sequential soil cores based on the maximum–minimum method in the 0–60 cm soil layer in three agricultural ecosystems and three natural ecosystems. Most (87% in agricultural and 75% in natural ecosystems) fine roots were distributed in the upper 30 cm soil layer. Mean annual fine roots production and turnover were 457% and 464% greater in agricultural than in natural ecosystems. Soil organic carbon input by fine roots decomposition was 91 g m−2 yr−1 in agricultural and 11 g m−2 yr−1 in natural ecosystems. Both fine roots biomass and fine roots production were significantly higher for two winter wheat (Triticum aestivum) ecosystems from May to October, 2010. Soil pH ranged from 8.2 to 9.4. Soil water content in agricultural ecosystems was higher, whereas soil electrical conductivity was lower than that in natural ecosystems. pH, soil bulk density, gravimetric soil water content, and soil electrical conductivity significantly affected fine roots biomass, production, turnover, and decomposition in all ecosystems investigated. The findings increase our understanding of the soil carbon cycle after natural ecosystems are modified into agricultural ecosystems.

Experimental and numerical comparisons of self-reacting point absorber wave energy converters in irregular waves

An experimental and numerical comparison of the performance of two self-reacting point absorber wave energy converter designs is undertaken for heave motions in irregular waves. The experiments consist of a series of 1:25 scale model tests that feature re-configurable WEC body shapes, a feedback controlled power take-off, and a heave motion constraint apparatus. While both designs have the same float, the first design features a streamlined reacting body and the second design features a damper plate reacting body. A time domain numerical model, validated by the experimental results, is used to extend the comparisons of the designs in terms of power matrices, capture width matrices, and mean annual power production. Results indicate that the wave energy converter design with damper plate produces 41% higher mean annual energy production than the wave energy converter design with streamlined reacting body at a representative location near the West Coast of Vancouver Island, British Columbia, Canada.

Mammalian faunas, ecological indices, and machine-learning regression for the purpose of paleoenvironment reconstruction in the Miocene of South America

Reconstructing paleoenvironments has long been considered a vital component for understanding community structure of extinct organisms, as well as patterns that guide evolutionary pathways of species and higher-level taxa. Given the relative geographic and phylogenetic isolation of the South American continent throughout much of the Cenozoic, the South American fossil record presents a unique perspective of mammalian community evolution in the context of changing climates and environments. Here we focus on one line of evidence for paleoenvironment reconstruction: ecological diversity, i.e. the number and types of ecological niches filled within a given fauna. We propose a novel approach by utilizing ecological indices as predictors in two regressive modeling techniques—Random Forest (RF) and Gaussian Process Regression (GPR)—which are applied to 85 extant Central and South American localities to produce paleoecological prediction models. Faunal richness is quantified via ratios of ecologies within the mammalian communities, i.e. ecological indices, which serve as predictor variables in our models. Six climate/habitat variables were then predicted using these ecological indices: mean annual temperature (MAT), mean annual precipitation (MAP), temperature seasonality, precipitation seasonality, canopy height, and net primary productivity (NPP). Predictive accuracy of RF and GPR is markedly higher when compared to previously published methods. MAT, MAP, and temperature seasonality have the lowest predictive error. We use these models to reconstruct paleoclimatic variables in two well-sampled Miocene faunas from South America: fossiliferous layers (FL) 1–7, Santa Cruz Formation (Early Miocene), Santa Cruz Province, Argentina; and the Monkey Beds unit, Villavieja Formation (Middle Miocene) Huila, Colombia. Results suggest general concordance with published estimations of precipitation and temperature, and add information with regards to the other climate/habitat variables included here. Ultimately, we believe that RF and GPR in conjunction with ecological indices have the potential to contribute to paleoenvironment reconstruction.

Estimated annual and lifetime labor productivity in the United States, 2016: implications for economic evaluations

Background: Human-capital based lifetime productivity estimates are frequently used in cost-of-illness (COI) analyses and, less commonly, in cost-effectiveness analyses (CEAs). Previous US estimates assumed that labor productivity and real earnings both grow by 1% per year.Objectives: This study presents estimates of annual and lifetime productivity for 2016 using data from the American Community Survey, the American Time Use Survey, and the Current Population Survey, and with varying assumptions about real earnings growth.Methods: The sum of market productivity (gross annual personal labor earnings adjusted for employer-paid benefits) and the imputed value of non-market time spent in household, caring, and volunteer services was estimated. The present value of lifetime productivity at various ages was calculated for synthetic cohorts using annual productivity estimates, life tables, discount rates, and assumptions about future earnings growth rates.Results: Mean annual productivity was $57,324 for US adults in 2016, including $36,935 in market and $20,389 in non-market productivity. Lifetime productivity at birth, using a 3% discount rate, is roughly $1.5 million if earnings grow by 1% per year and $1.2 million if future earnings growth averages 0.5% per year.Conclusions: Inclusion of avoidable productivity losses in societal-perspective CEAs of health interventions is recommended in new US cost-effectiveness guidelines. However, estimates vary depending on whether analysts choose to estimate total productivity or just market productivity, and on assumptions made about growth in future productivity and earnings.

Ecological envelope maps and stand production of eucalyptus plantations and naturally regenerated maritime pine stands in the central inland of Portugal

Eucalyptus and maritime pine forests provide most of the wood harvested in Portugal. Due mainly to forest fires maritime pine forest has been converted to eucalyptus plantations. In the central inland of Portugal these species are well represented, and their productivities are quite the same. The objectives of the study were: (1) to assess average wood volume, biomass production and carbon content of eucalyptus plantations and naturally regenerated maritime pine stands; (2) to evaluate biomass nutrients concentration of eucalyptus sprouts selection and maritime pine non-commercial thinning; (3) to analyse these forests cover change in relation to the annual burnt areas; and (4) to produce the species ecological envelope maps to foresee future environmental impacts of these forests current distribution. Simulation models were used to assess wood volume, biomass production and carbon content. Field data was collected to evaluate biomass nutrients concentration and to validated simulated data. Forest inventory data and forest cover maps were used to analyse forest cover change. Biogeographical variables were used to produce species ecological envelope maps. It was found that eucalyptus plantations provide higher mean annual wood volume, biomass production and carbon content. Biomass nutrients concentration in eucalyptus sprouts selection were higher than in maritime pine non-commercial thinning, particularly in calcium and potassium. Overall eucalyptus forests area did not increase substantially but the fires in maritime pine forests gave the opportunity for eucalyptus afforestation. That has precluded the opportunity for introducing native broadleaves to respond to climate changes, improve landscape biodiversity and mitigate fire hazard. Implementing good management practices to prevent losses of soil fertility by nutrients exhaustion, organic matter depletion or erosion were found more relevant in eucalyptus plantations than in naturally maritime pine forest. Species ecological envelope maps and production simulation models are key tools for supporting decision in afforestation planning.

Plant Production Responses to Precipitation Differ Along an Elevation Gradient and Are Enhanced Under Extremes

The sensitivity of plant production to precipitation underlies the functioning of ecosystems. Studies that relate long-term mean annual precipitation and production across multiple sites (spatial relationship) or examine interannual linkages within a site (temporal relationship) can reveal biophysical controls over ecosystem function but have limited ability to infer responses to extreme changes in precipitation that may become more common under climate change. To overcome limitations of using a single approach, we integrated satellite- and ground-based estimates of production with a standardized, multi-site precipitation manipulation experiment across a grassland elevation gradient in the southwestern USA. The responsiveness of production to changes in precipitation followed the order: temporal (0.06–0.13 g m−2 mm−1) < spatial (0.21 g m−2 mm−1) < experimental relationship (0.25–0.42 g m−2 mm−1), suggesting that spatial and temporal relationships determined with satellite- and ground-based estimates cannot be extrapolated to determine the effect of extreme events. A strong production response to differences in mean annual precipitation across sites reinforces a regional control of water availability. Interannual sensitivity to precipitation was strongest at the low elevation grasslands, and the high elevation mixed conifer meadow had a large reduction in production in a drought year. Extreme experimental drought strongly reduced production in low elevation grasslands, but water addition had mixed effects. High elevation meadows were insensitive to both extreme drought and water addition. Our results highlight the importance of accounting for extreme climate regimes and site-level factors when scaling climate change effects up to regional and global scales.

Las tesis doctorales en radiodiagnóstico: estudio de la producción española entre 1976 y 2011

ObjectiveTo analyze the production of doctoral theses in diagnostic imaging in Spain in the period comprising 1976 through 2011 with the aim of a) determining the number of theses and their distribution over time, b) describing the production in terms of universities and directors, and c) analyzing the content of the theses according to the imaging technique, anatomic site, and type of research used. Material and methodsThe TESEO database was searched for “radiología” and/or “diagnóstico por imagen” and for terms related to diagnostic imaging in the title of the thesis. ResultsA total of 1036 theses related to diagnostic imaging were produced in 37 Spanish universities (mean, 29.6 theses/year; range, 4–59). A total of 963 thesis directors were identified; 10 of these supervised 10 or more theses. Most candidates and directors were men, although since the 2000–2001 academic year the number of male and female candidates has been similar. The anatomic regions most often included in diagnostic imaging theses were the abdomen (22.5%), musculoskeletal system (21.8%), central nervous system (16.4%), and neck and face (15.6%). The imaging techniques most often included were ultrasonography in the entire period (25.5%) and magnetic resonance imaging in the last 5 years. Most theses (63.8%) were related to clinical research. ConclusionsDespite certain limitations, the TESEO database makes it possible to analyze the production of doctoral theses in Spain effectively. The annual mean production of theses in diagnostic imaging is higher than in other medical specialties. This analysis reflects the historic evolution of imaging techniques and research in radiology as well as the development of Spanish universities.