Regional Differences In Climate Research Articles

Limitations of climatic data for inferring species boundaries: insights from speckled rattlesnakes.

Phenotypes, DNA, and measures of ecological differences are widely used in species delimitation. Although rarely defined in such studies, ecological divergence is almost always approximated using multivariate climatic data associated with sets of specimens (i.e., the “climatic niche”); the justification for this approach is that species-specific climatic envelopes act as surrogates for physiological tolerances. Using identical statistical procedures, we evaluated the usefulness and validity of the climate-as-proxy assumption by comparing performance of genetic (nDNA SNPs and mitochondrial DNA), phenotypic, and climatic data for objective species delimitation in the speckled rattlesnake (Crotalus mitchellii) complex. Ordination and clustering patterns were largely congruent among intrinsic (heritable) traits (nDNA, mtDNA, phenotype), and discordance is explained by biological processes (e.g., ontogeny, hybridization). In contrast, climatic data did not produce biologically meaningful clusters that were congruent with any intrinsic dataset, but rather corresponded to regional differences in atmospheric circulation and climate, indicating an absence of inherent taxonomic signal in these data. Surrogating climate for physiological tolerances adds artificial weight to evidence of species boundaries, as these data are irrelevant for that purpose. Based on the evidence from congruent clustering of intrinsic datasets, we recommend that three subspecies of C. mitchellii be recognized as species: C. angelensis, C. mitchellii, and C. Pyrrhus.

Climate change projections for CORDEX-Africa with COSMO-CLM regional climate model and differences with the driving global climate models

In the framework of the coordinated regional climate downscaling experiment (CORDEX), an ensemble of climate change projections for Africa has been created by downscaling the simulations of four global climate models (GCMs) by means of the consortium for small-scale modeling (COSMO) regional climate model (RCM) (COSMO-CLM, hereafter, CCLM). Differences between the projected temperature and precipitation simulated by CCLM and the driving GCMs are analyzed and discussed. The projected increase of seasonal temperature is found to be relatively similar between GCMs and RCM, although large differences (more than 1 °C) exist locally. Differences are also found for extreme-event related quantities, such as the spread of the upper end of the maximum temperature probability distribution function and, in turn, the duration of heat waves. Larger uncertainties are found in the future precipitation changes; this is partly a consequence of the inter-model (GCMs) variability over some areas (e.g. Sahel). However, over other regions (e.g. Central Africa) the rainfall trends simulated by CCLM and the GCMs show opposite signs, with CCLM showing a significant reduction in precipitation at the end of the century. This uncertain and sometimes contrasting behaviour is further investigated by analyzing the different models’ response to the land–atmosphere interaction and feedback. Given the large uncertainty associated with inter-model variability across GCMs and the reduced spread in the results when a single RCM is used for downscaling, we strongly emphasize the importance of exploiting fully the CORDEX-Africa multi-GCM/multi-RCM ensemble in order to assess the robustness of the climate change signal and, possibly, to identify and quantify the many sources of uncertainty that still remain.

A review of the global relationship among freshwater fish, autotrophic activity, and regional climate

The relationship between autotrophic activity and freshwater fish populations is an important consideration for ecologists describing trophic structure in aquatic communities, fisheries managers tasked with increasing sustainable fisheries development, and fish farmers seeking to maximize production. Previous studies of the empirical relationships of autotrophic activity and freshwater fish yield have found positive relationships but were limited by small sample sizes, small geographic scopes, and the inability to compare patterns among many types of measurement techniques. Individual studies and reviews have also lacked consistent consideration of regional climate factors which may inform relationships between fisheries and autotrophic activity. We compiled data from over 700 freshwater systems worldwide and used meta-analysis and linear models to develop a comprehensive global synthesis between multiple metrics of autotrophic activity, fisheries, and climate indicators. Our results demonstrate that multiple metrics of fish (i.e., catch per unit effort, yield, and production) increase with autotrophic activity across a variety of fisheries. At the global scale additional variation in this positive relationship can be ascribed to regional climate differences (i.e., temperature and precipitation) across systems. Our results provide a method and proof-of-concept for assessing inland fisheries production at the global scale, where current estimates are highly uncertain, and may therefore inform the continued sustainable use of global inland fishery resources.

Variability and rapid response of subalpine fir (Abies fargesii) to climate warming at upper altitudinal limits in north-central China

In the Qinling Mountains of north-central China, subalpine fir treelines exhibited a significant upward movement on the northern slope, but only a slight change on the southern slope over the past 200 years, supporting the idea that pattern and timing of treeline change are contingent on local environmental conditions. Variability in the response of altitudinal treelines to climate change might be contingent on species-specific characteristics and on different climate. The objective of this study was to examine the pattern, timing and variability in response of Abies fargesii treeline to climate warming among topographically similar, but climatically different sites. Rectangular plots were established across subalpine fir treeline ecotones on the northern and southern slopes of the Qinling Mountains. Dendroecological techniques were used to examine treeline patterns and dynamics at 50-year intervals. The results showed that despite the differences in regional climate, all the plots studied displayed a recent rapid recruitment trend. Tree recruitment was favored by high spring–summer temperatures on the northern slope and by high summer temperatures on the southern slope. Subalpine fir treelines exhibited a significant upward movement on the northern slope, but only a slight change on the southern slope over the past 200 years. The variability in changes of treeline position on the northern and southern slope can be attributed to the differences in regional climate conditions, supporting the idea that pattern and timing of treeline change is contingent on local environmental conditions.

The effects of eucalypt plantations on plant litter decomposition and macroinvertebrate communities in Iberian streams

Eucalypt plantations cover over 1.5 million ha in the Iberian Peninsula. The effects of the replacement of native deciduous forests by exotic plantations on stream communities and litter decomposition, a key ecosystem process in forest streams, are poorly understood. We compared microbially driven and total (microbes+invertebrates) decomposition of alder and oak leaf litter (high and low quality resource, respectively) as well as macroinvertebrate communities associated with decomposing litter and in the benthos, in five streams flowing through native deciduous broad-leaved forests and five streams flowing through eucalypt plantations in central Portugal and northern Spain (20 streams total). Total decomposition rate of alder leaf litter was slower in eucalypt than in deciduous streams, which was attributed to lower macroinvertebrate (and also shredder) colonization. No major effects of eucalypt plantations were found on macroinvertebrate colonization and total decomposition of oak litter, likely due to the low contribution of invertebrates to the decomposition of nutrient-poor litter. Microbially driven litter decomposition was generally not affected by forest change, likely due to high functional redundancy among microbes. Eucalypt streams had fewer invertebrates in Portugal than in Spain, which might be attributed to summer droughts in Portugal and the absence of deciduous riparian corridors in eucalypt plantations. In northern Spain, the relatively wet climate allows streams to flow year-round and eucalypt plantations have riparian deciduous trees that mitigate the effects of plantations. This study highlights the need to consider regional differences in climate, native vegetation, and the importance of macroinvertebrates, when assessing the effects of plantations on stream ecosystem processes such as carbon cycling. It also suggests that preservation of native riparian corridors, especially in drier areas, where the native vegetation provides high quality litter to the streams, and where invertebrates play an important role in aquatic processes, may mitigate the effects of plantations on stream communities and processes.

Climate change regionalization in China (1961–2010)

Since climatic condition is the important foundation for human subsistence and development and the key factor in sustainable development of economy and society, climate change has been a global issue attracting great attentions of politicians, scientists, governments, and the public alike throughout the world. Existing climate regionalization in China aims to characterize the regional differences in climate based on years of the mean value of different climate indexes. However, with the accelerating climate change nowadays, existing climate regionalization cannot represent the regional difference of climate change, nor can it reflect the disasters and environmental risks incurred from climate changes. This paper utilizes the tendency value and fluctuation value of temperature and precipitation from 1961 to 2010 to identify the climate change quantitatively, and completes the climate change regionalization in China (1961-2010) with county administrative regionalization as the unit in combination with Chinas terrain feature. Level-I regionalization divides Chinas climate change (1961-2010) into five tendency zones based on the tendency of temperature and precipitation, which are respectively Northeast China-North China warm-dry trend zone, East China-Central China wet-warm trend zone, Southwest China-South China dry-warm trend zone, Southeast TibetSouthwest China wet-warm trend zone, and Northwest China-Qinghai-Tibet Plateau warm-wet trend zone; level-II regionalization refers to fourteen fluctuation regions based on level-I regionalization according to the fluctuation of temperature and precipitation.

Extracting grassland vegetation phenology in North China based on cumulative SPOT-VEGETATION NDVI data

Plant phenology is one of the main indicators of climate or other environmental processes. This paper assesses the detection accuracy of start of season (SOS) and end of season (EOS) for grassland vegetation in north China from 2001 to 2010 using SPOT-VEGETATION normalized difference vegetation index (NDVI) data sets and in situ observations. The cumulative NDVI is calculated and fitted using a logistic model to identify phenological transition dates. The curvature of the fitted logistic models predicts phenological transition dates that correspond to the times at which the curvature in the yearly integrated NDVI exhibits local minimums or maximums. Validating with in situ observations, phenological dates are extracted from satellite time series data and are accurate to within 10 days. The spatial trends of SOS and EOS are very similar for 2001–2010. SOS mainly occurs from the day of year (DOY) 110 to DOY 170, and EOS occurs from DOY 240 to DOY 300. SOS displays a marked delay from south to north, while EOS gradually advances, indicating regional differences in climate and terrain. However, the effect of latitude and longitude on the average EOS of alpine grasslands is not significantly different, while SOS at low latitude and high longitude is 10 days earlier than at high-latitude and high-longitude regions. We detected an overall advance in SOS of 3.1 days over 10 years, and a 1.3-day delay in EOS. However, the amplitude is low (about 5 days) and the changes in most regions are not significant (close to zero). The results in this paper are concordant with many reported studies that explored the phenology of grasslands in North China, which is an important component of global grasslands science.

Modeling regional and climatic variation of wood density and ring width in intensively managed Douglas-fir

Characteristics of annual rings are reliable indicators of growth and wood quality in trees. The main objective of our study was to model the variation in annual ring attributes due to intensive silviculture and inherent regional differences in climate and site across a wide geographic range of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco). Ring specific gravity and ring width of Douglas-fir were examined at five long-term Levels-Of-Growing-Stock (LOGS) installations, three in the US and two in Canada, covering a latitudinal gradient between 43°N and 50°N. At each location, increment cores were collected from replicated plots with three levels of stocking: control (unthinned), lightly thinned (70% basal area retention), and heavily thinned (30% basal area retention). X-ray densitometry analysis provided ring specific gravity and width profiles for 5676 rings from 134 trees. The reduction of stand density through repeated entries resulted in decreased ring specific gravity and increased ring width. A four-parameter mixed-effects logistic model was used to predict ring specific gravity using cambial age, stand density (as number of stems per hectare), and two climatic variables: average temperature from March to May and total precipitation from April to August. A three-parameter mixed-effects logistic model was used to predict ring width using cambial age, stand density (as stand density index), and total climatic moisture deficit of June and July. Both models indicated significant site differences that were included in the models through indicator variables. Ring specific gravity increased slightly with increasing average temperature from March to May and decreasing total precipitation from April to August. Predictions of ring specific gravity of Douglas-fir appear to be more sensitive to changes in temperature compared with changes in precipitation.

Reproductive seasonality in African ungulates in relation to rainfall

Context Reproductive seasonality in ungulates has important fitness consequences but its relationship to resource seasonality is not yet fully understood, especially for ungulates inhabiting equatorial environments. Aims We test hypotheses concerning synchronisation of conception or parturition peaks among African ungulates with seasonal peaks in forage quality and quantity, indexed by rainfall. Methods We relate monthly apparent fecundity and juvenile recruitment rates to monthly rainfall for six ungulate species inhabiting the Masai Mara National Reserve (Mara) of Kenya, using cross-correlation analysis and distributed lag non-linear models. We compare the phenology and synchrony of breeding among the Mara ungulates with those for other parts of equatorial East Africa, with bimodal rainfall and less seasonal forage variation, and for subtropical southern Africa, with unimodal rainfall distribution and greater seasonal forage variation. Key results Births were more synchronised for topi, warthog and zebra than for hartebeest, impala and giraffe in the Mara, and for impala and hartebeest in southern than in eastern Africa. This pattern is likely to reflect regional differences in climate and plant phenology, hider–follower dichotomy and grazing versus browsing. All six species except the browsing giraffe apparently time the conception to occur in one wet season and births to occur just before the onset or during the next wet season, so as to maximise high-quality forage intake during conception and parturition. Fecundity and recruitment rates among the African ungulates peak at intermediate levels of rainfall and are reduced at low or excessive levels of rainfall. Fecundity rate is most strongly positively correlated with rainfall pre-conception, during conception and during early gestation, followed by rainfall at about the time of parturition for all the grazers. For giraffe, fecundity rate is most strongly correlated with rainfall during the gestation period. Conclusions Rainfall seasonality strongly influences reproductive seasonality and juvenile recruitment among African ungulates. The interaction of the rainfall influence with life-history traits and other factors leads to wide interspecific and regional variation. Implications Global climate change, especially widening annual rainfall variation expected to result from global warming, could reduce the predictability of the timing of peak forage availability and quality based on meteorological cues, the length of time with adequate nutrition or both, and hence reduce reproductive success among tropical ungulates.

Applicability of ASHRAE Standard 55 and EN 15251 Adaptive Thermal Comfort Models in Hot-and-Humid Climate

Background: The inclusion of adaptive thermal comfort model in the ASHRAE Standard 55 and EN 15251 exemplifies the increasing effort of improving indoor environmental quality in naturally ventilated buildings. However the applicability of these models in areas of hot-and-humid climate such as Taiwan has been only insufficiently validated. Aims: This study examined the boundaries of thermal comfort zones as predicted by the ASHRAE and EN models to those established by a field study conducted in Taiwan to examine the discrepancies between these models as well as between the model projection and field observation so to evaluate the models’ local applicability. Methods: A field study was conducted to investigate the adaptive thermal comfort in 113 naturally ventilated classrooms of 14 schools in central Taiwan. For a total period of five months consisting of summer, autumn and winter conditions, questionnaire survey were performed to observe the actual thermal sensation of the students in relation to the thermal status in the ambient environment when the school was in session. The observed thermal acceptability was analyzed against those projected by the ASHRAE and EN models using local meteorological data. Results: Both the ASHRAE and EN models significantly underestimated the thermal acceptability of Taiwanese when the ambient temperature fell outside the range of approximately 20 to 30oC. When the upper limit of the comfort zones projected by these models was compared, the predictability of the ASHRAE model appeared to be less than that of the EN model in the warm condition. The EN comfort zones Category I and II were more consistent to field observations than the ASHRAE comfort zones 90 and 80%. Conclusions: When applied to specific regions the ASHRAE and EN adaptive comfort models should be first assessed for applicability and calibrated to accommodate regional differences in climate and in patterns of thermal adaptation.

Effects of edaphic conditions on site quality for Salix purpurea ‘Hotel’ plantations across a large climatic gradient in Canada

Willow has been identified as a possible species for supplying large quantities of biomass for bioenergy and wood fibers in Canada. However, before site selection occurs, there is a need to know how the soils and climate of the prairies and central regions affect willow productivity. Soil, foliar, and climatic variables were therefore measured along with yields at nine “first rotation” Salix purpurea ‘Hotel’ plantations from central Alberta to southern Ontario. Correlation analysis was used to identify those parameters having the most influence on yields. Relationships between soil and climate and growth were established by regression analysis. The acid–base status of the soil as dictated by bulk elemental composition, in particular the presence of Ca, was found to be the dominant factor affecting productivity (r = 0.967, P < 0.001 total Ca vs. yields) despite large regional differences in climate. From a nutritional standpoint, total soil N (r = 0.743, P = 0.048) and foliar K (r = 0.938, P = 0.009 for sites with adequate moisture) were positively correlated with growth. S. purpurea ‘Hotel’ yields were found to be primarily limited by water availability at the two lowest productivity prairie sites. Soil total Ca concentration, pH and total organic C concentration were all generally correlated with higher yields. Additional deficiencies appeared in the following order of importance: water > N and K > Mg. As a whole, soil properties were the dominant predictors of ‘Hotel’ growth in this study, which suggests that, even at the regional scale, growth was governed in large part by the capacity of soils to retain water and/or nutrients. Climate played a lesser role, except perhaps at two sites which appeared to receive inadequate moisture.

Climate Change Impact on the Air Quality: The Portuguese Case

The changes in greenhouse gases and aerosols emissions are expected to lead to regional and global changes in temperature, precipitation, and other climate variables. The degree to which human conditions and the natural environment are vulnerable to the potential effects of climate change is a key concern for governments and the environmental science community. Regional differences in climate change and its impacts have recently been identified as current gaps in the present scientific knowledge. Air quality regional impacts of global climate change, namely the effects on photochemical production, are not a common subject of scientific studies. The main objective of this paper is to provide a basis of scientific information for policy makers and public use by the assessment of the vulnerability of Portuguese air quality to climate change. A General Circulation Model was applied in order to provide initial and driving meteorological boundary conditions, assuming a present climate situation and a scenario of double carbon dioxide concentration in the atmosphere, for higher resolution mesometeorological and photochemical models. Results emphasise a possible significant impact of the climate change scenario on the photochemical pollution, namely at noon.

The application of an oxygen isotope aridity index to terrestrial paleoenvironmental reconstructions in Pleistocene North America

Geochemical tools, including the analysis of stable isotopes from fossil mammals, are often used to infer regional climatic and environmental differences. We have further developed an oxygen isotope aridity index and used oxygen (δ18O) isotope values and carbon (δ13C) isotope values to assess regional climatic differences between the southeastern and southwestern United States during the Pleistocene. Using data collected from previously published studies, we assigned taxa to evaporation-sensitivity categories by quantifying the frequency and magnitude of aridity index values (i.e., an average taxon δ18O value minus a site specific proboscidean δ18O value). Antilocapridae, Camelidae, Equidae, and Cervidae were identified as evaporation-sensitive families, meaning that a majority of their water comes from the food they eat, thus indicating that they are more likely to capture changing climatic conditions. Bovidae, Tayassuidae, and Tapiridae were identified as less sensitive families, possibly because of increased or more variable drinking behavior. While it is difficult to tease out individual influences on δ18O values in tooth enamel, the use of an aridity index will provide a more in-depth look at relative aridity in the fossil record. Greater aridity index values in the Southwest suggest a drier climate than in the Southeast during the Pleistocene, and δ13C values suggest that diet does not determine evaporation sensitivity. The combination of more-positive δ13C values and the lack of forest indicator taxa in the Southwest suggest that landscapes were more open than in the Southeast. Inferred higher aridity in the Southwest may indicate that aridity or seasonal aridity/precipitation, not temperature orpCO2, was a greater driver of C4abundance during the Pleistocene. Collectively, these data suggest that regional climatic and environmental interpretations can be improved by using an aridity index and a more detailed understanding of mammalian paleobiology.

Climate and the effectiveness of Psyllaephagus bliteus as a parasitoid of the red gum lerp psyllid

The encyrtid parasitoid Psyllaephagus bliteus Riek was introduced to California in 2000 to control the red gum lerp psyllid, Glycaspis brimblecombei Moore. Field experiments were conducted to determine the effect of regional summer climate (California coastal vs. interior valleys) on P. bliteus performance. Measurements of parasitoid performance, including reproduction and longevity, showed that P. bliteus was adversely affected by the extreme summer heat in the interior valley sites. The results suggest that regional climatic differences can contribute to the lower parasitism rates observed in California's warmer interior valleys. The results are discussed with respect to biological control of G. brimblecombei and the potential limitations of the parasitoid P. bliteus, as well as the possible impact of climate and intraguild predation as alternative hypotheses for the observed variable geographic performance of P. bliteus.

Evaluating the effect of flowering age and forest structure on pollen productivity estimates

Pollen productivity estimates (PPEs) are indispensable prerequisites for quantitative vegetation reconstructions. Estimates from different European regions show a large variability and it is uncertain whether this reflects regional differences in climate and soil or is brought about by different assessments of vegetation abundance. Forests represent a particular problem as they consist of several layers of vegetation and many tree species only start producing pollen after they have attained ages of several decades. Here we used detailed forest inventory data from north-eastern Germany to investigate the effect of flowering age and understory trees on PPEs. Pollen counts were obtained from 49 small to medium sized lakes chosen to represent the different forest types in the region. Surface samples from lakes within a closed forest of Fagus yielded disproportionate amounts of Fagus pollen, increasing its PPE and the variability of all other estimates. These samples were removed from further analysis but indicate a high trunk-space component that is not considered in the Prentice–Sugita pollen dispersal and deposition model. Results of the restricted dataset show important differences in PPEs based on the consideration of flowering age and understory position. The effect is largest for slow growing and/or late flowering trees like Fagus and Carpinus while it is minimal for species that flower early in their development like Betula and Alnus. The large relevant source area of pollen (RSAP) of 7 km obtained in this study is consistent with the landscape structure of the region.

Urban Tree Growth Modeling

Selecting, locating, and managing trees to provide ecosystem services are becoming increasingly important facets of municipal and consulting forestry. The science of urban tree growth modeling is fundamental to quantifying these services. This paper describes three longterm tree growth studies conducted to evaluate tree performance because repeated measurements of the same trees produce critical data for growth model calibration and validation. Several empirical and process-based approaches to modeling tree growth are reviewed. Modeling is more advanced in the fields of forestry and pomology than in urban forestry. The USDA Forest Service’s reference city research has developed over 1,800 growth equations from measurements on more than 17,000 trees in 16 cities. The database is a valuable source of information that reflects regional differences in species composition, climate, soils, site conditions, and management practices. Several examples illustrate how differences in local climate and management practices can influence growth of a single species and the resulting value of services. Further advances in urban tree growth modeling are needed to inform the design, management, and modeling of high performing landscapes.

Loess record of climatic changes during MIS 12–10 in the Jingyuan section, northwestern Chinese Loess Plateau

Marine Isotope Stage 11 (MIS 11) has been considered as a potential analog for the present interglacial, based on orbital scale solar insolation variations. Therefore, increasing attention has been paid to MIS 11 and the contiguous stages in recent studies of marine and terrestrial records, as they may provide clues for predictions of future climate change. In the Chinese loess-palaeosol sequences, S4 soil, interpreted as corresponding to MIS 11, yields a precise terrestrial palaeoclimate record for this period. In this study, a loess-palaeosol sequence (L4–L5) from the Jingyuan Section on the northwestern margin of the Chinese Loess Plateau (CLP) was investigated to reconstruct the climatic variability during the periods MIS 12–10, using proxies of grain size, magnetic susceptibility, total organic carbon and soil color index. The results suggest that the L4–L5 sequence in the Jingyuan Section is much thicker (∼40 m) than those in the central Loess Plateau areas (∼12 m). The L5 loess, equivalent to MIS 12, developed under relatively cold and dry conditions. Climate evolution during this period was not as severe as that indicated in the marine isotopic records. An episode of warmer and more humid conditions occurred during the middle stages of MIS 12, reflecting a strengthened summer monsoon during the glacial period. A similar scenario has been observed in the middle part of MIS 10. High-resolution multi-proxy records for MIS 11 suggest that a general warm–humid climate was dominant during the formation of S4 soil. However, at least four fluctuations occurred, reflecting unstable climate conditions and regional climate differences within the northwestern margin of the CLP during this period. The study also shows that the early part of S4, spanning over 30 ky, was very warm and humid, while the later part was characterized by mild-cool conditions.

Subjective estimations of thermal environment in recreational urban spaces—Part 2: international comparison

The present paper is the second part of our study in which we compare the results obtained in Szeged (Hungary) with those achieved through earlier outdoor thermal comfort projects based on simultaneous questionnaire surveys and on-site meteorological measurements. The main characteristics of the selected studies--conducted in Hungary, Sweden, Portugal, Canada, Taiwan and across Europe in the frame of project RUROS--are reviewed, emphasizing the common features and also the discrepancies in the applied methodology. We discuss their potential effects on the evolution and interpretation of the results concerning the subjective assessment of the thermal environment. Another aspect of the comparison focuses on the regional climatic differences naturally ensuing from the various locations, which left their marks on the results related to both physiological acclimatization and mental adaptation. The compared results of different studies include correlation coefficients expressing interrelationships between the different aspects of subjective estimations (thermal sensation, perceptions, preferences) and also between subjective assessments and the corresponding meteorological parameters. We compare neutral temperatures (expressed in physiological equivalent temperature, PET) which arose for Taiwan and Hungary, as well as thermal sensation zones for local inhabitants. Subjectively assessed temperature values of Sweden and Hungarians are analyzed according to the measured air temperature. According to our experiences the methodology should be standardized for the level of field surveys and also for the level of data processing in order to make the data collected in different locations comparable.

A case study of the potential environmental impacts of different dairy production systems in Georgia

The biological and physical processes of an intensively-managed rotational pasture-based dairy and a confinement fed dairy in the southeastern United States were simulated with the Integrated Farm System Model (IFSM) to evaluate management effects on greenhouse gas emissions, soil carbon sequestration, carbon footprint, nitrate leaching, ammonia volatilization, erosion, phosphorus runoff, and phosphorus accumulation in the soil. Edge-of-field erosion and phosphorus runoff were less for the pasture-based dairy per unit of land and per unit of milk produced, but nitrate leaching was greater. Ammonia emissions were greater from the confinement dairy because of the greater handling of manure. Greenhouse gas emissions per cow were greater on the confined dairy, but with greater milk production per cow, the carbon footprint of milk produced was similar to that of the pasture-based dairy. Considering the potential soil carbon sequestration following the conversion of crop land to perennial grassland, the carbon footprint of the milk produced by the pasture-based dairy was slightly less than that of the confinement dairy. The results of this study were generally consistent with similar simulation studies done in the northeastern US with variations due to regional differences in climate, soil type, and agronomic practices. Simulated changes in production practices predicted that increasing milk production through improved animal management or feeding more corn decreased the carbon footprint of milk produced by the pasture-based dairy, while decreasing the inorganic nitrogen fertilizer application rate or raising replacement heifers on the farm had little effect. On the confinement dairy, covering the manure storage and flaring the biogas decreased the carbon footprint, using higher producing, pure-bred Holstein cows or producing less forage on the farm increased the footprint, and eliminating free-stall barns and placing all cattle on pasture had little effect on the footprint. The IFSM was capable of adapting to the climate and production practices of the southeastern US, but further improvements could be made to better represent the cropping practices used in this region.

Determinants of sickness absence duration after an occupational back injury in the belgian population

This study aimed at assessing factors associated to the duration of sickness absence after a back injury in the Belgian working population, with a special emphasis on cultural factors. The data were retrieved from the Belgian Fund for Work Accidents database over a 3-year period (2001-2003). The population source involved all Belgian workers under a job contract in the private sector registered as compensated cases for an accident that occurred at the workplace (n = 558,276). From that database, all back injury cases involving a complete data set and registered during the first 6 months of each year (n = 11,262) were selected and eight factors (gender, age, seniority in the current job, job category, accident regional location, enterprise size, sector of activity, and accident circumstances) were analyzed in relation to the outcome variable, sick leave duration recorded as ordered time intervals between 0 and 183-366 days. Sick leave duration was strongly associated in a multivariate model to age (≥40 years: OR = 2.18), blue-collar job (1.55), work in building industry (1.32), and enterprise size (>100: 0.85), and to a less extent to seniority (>10y: 0.88), and circumstance of accident (falls: 1.26). Injuries occurring in the French-speaking part of the country were associated to a longer sick leave (1.07; P = 0.034). This study shows that besides well-known risk factors, subtle cultural language-linked factors and/or regional differences in economic climate may significantly influence the length of disability period after a back injury.