Analyses of landuse change impacts on catchment runoff using different time indicators based on SWAT model

Previous researches mainly focused on the runoff responses to landuse change based on annual, seasonal or monthly time scales, there are few studies based on daily scale. We conducted a comprehensive investigation into runoff responses on the daily scale as well as annual and monthly time scales using SWAT, and compared the impacts of time scales with different time indicators quantitatively. Jinjiang, a coastal catchment of southeast China with a humid sub-tropical climate, was used for simulations. A calibrated SWAT model produced satisfactory reproduction of annual, monthly and daily runoff processes over a nine-year (2002–2010) period at three gauging stations. Runoff was then simulated and compared using the same meteorological input but two different landuse scenarios (1985 and 2006, with reduced forest and increased cropland and urbanized area). The results showed varying change in runoff among three time scales and three catchments. The annual runoff had the smallest increase between two scenarios, monthly runoffs had medium rates (increasing in all months except October–November), and daily runoff had the largest rates with the increase in flood peaks but decrease in drought flows, because of the variable influence on interception/evapotranspiration loss, percolation and antecedent soil water storage. Indicators of different time scales (annual runoff, monthly runoff, maximum 1-day and 5-day flood runoff, minimum 1-day and 7-day runoff) proved appropriate for analysing landuse change impacts.     

Tree-rings,a key ecological indicator of environment and climate change

Due to wide spatial distribution, high annual resolution, calendar-exact dating, and high climate sensitivity, tree-rings play an important role in reconstructing past environment and climate change over the past millennium at regional, hemispheric or even global scales, so tree-rings can help us to better understand climate behaviour and its mechanisms in the past and then predict variation trends for the future. In this paper, we will review latest advances in tree-ring-based climate reconstructions in China and their applications in modelling past local/regional climate change, capturing historical climatic extreme events, as well as analyzing their link to large-scale climate patterns.     

Menarcheal age in medio-altitude sample. Comparison with another populations of same province. Cuenca (Spain)

Environmental contributions to variation on menarcheal age were studied in 2018 Spanish girls and women from de Province of Cuenca. (Spain). This province has a big variation in altitude and is one of the most representative as middle-altitude population in Spain. Maturation's delay in high populations is well referenced but there are less studies in European middle-altitude populations. To give news about this topic is the main objective of this paper. Retrospective Method was employed in adult sample and Status-Quo in young population (9 to 15 years old) Another social, nutritional, somatic and educational levels was recording to give a variation contest. Our study shows a significantly variation between the provincial areas. In effect, the population of “Sierra”, the mountain region has the last maturation in the adults (13.45±0.73) as well as in girls (13.26±1.07). Secular change was observed in relation with this parameter., but less intense that in total, of province. We can confirm the utility of the age of menarche as evaluator of human variation in time and ecological situations.     

Evidence for increases in vegetation species richness across UK Environmental Change Network sites linked to changes in air pollution and weather patterns

We analysed trends in vegetation monitored at regular intervals over the past two decades (1993–2012) at the twelve terrestrial Environmental Change Network (ECN) sites. We sought to determine the extent to which flora had changed and link any such changes to potential environmental drivers. We observed significant increases in species richness, both at a whole network level, and when data were analysed within Broad Habitat groupings representing the open uplands, open lowlands and woodlands. We also found comparable increases in an indicator of vegetation response to soil pH, Ellenberg R. Species characteristic of less acid soils tended to show more consistent increases in frequency across sites relative to species with a known tolerance for strongly acidic soils. These changes are, therefore, broadly consistent with a response to increases in soil solution pH observed for the majority of ECN sites that, in turn, are likely to be driven by large reductions in acid deposition in recent decades. Increases in species richness in certain habitat groupings could also be linked to increased soil moisture availability in drier lowland sites that are likely to have been influenced by a trend towards wetter summers in recent years, and possibly also to a reduction in soil nitrogen availability in some upland locations. Changes in site management are also likely to have influenced trends at certain sites, particularly with respect to agricultural practices. Our results are therefore indicative of widescale responses to major regional-scale changes in air pollution and recent weather patterns, modified by local management effects. The relative consistency of management of ECN sites over time is atypical of much of the wider countryside and it is therefore not appropriate to scale up these observations to infer national scale trends. Nevertheless the results provide an important insight into processes that may be operating nationally. It will now be necessary to test for the ubiquity of these changes using appropriate broader spatial scale survey data.     

Changes in plant species richness and productivity in response to decreased nitrogen inputs in grassland in southern England

Biomass production and plant species diversity in grassland in southern England was monitored before and after a change from conventional to organic farming. Our 18-year study, part of the UK's Environmental Change Network long-term monitoring programme, showed that the cessation of artificial fertiliser use on grassland after conversion to organic farming resulted in a decrease in biomass production and an increase in plant species richness. Grassland productivity decreased immediately after fertiliser application ceased, and after two years the annual total biomass production had fallen by over 50%. In the subsequent decade, total annual grassland productivity did not change significantly, and yields reached 31–66% of the levels recorded pre-management change. Plant species richness that had remained stable during the first 5 years of our study under conventional farming, increased by 300% over the following 13 years under organic farm management. We suggest that the change in productivity is due to the altered composition of species within the plots. In the first few years after the change in farming practice, high yielding, nitrogen-loving plants were outcompeted by lower yielding grasses and forbs, and these species remained in the plots in the following years. This study shows that grassland can be converted from an environment lacking in plant species diversity to a relatively species-rich pasture within 10–15 years, simply by stopping or suspending nitrogen additions. We demonstrate that the trade-off for increasing species richness is a decrease in productivity. Grassland in the UK is often not only managed from a conservation perspective, but to also produce a profitable yield. By considering the species composition and encouraging specific beneficial species such as legumes, it may be possible to improve biomass productivity and reduce the trade-off.     

Research Symposium—Aberdeen

ABSTRACT

Background: Climate change may increase the risk of biological invasions. However, current knowledge of this interaction is limited.

Aims: We aimed to quantify (1) the effect of climate change on the potential distribution of invasive plant species in Spain, (2) the importance of the area of origin of such species and (3) the vulnerability of different biogeographic provinces to future changes in climatic suitability for invaders.

Methods: We applied six methods of species distribution modelling to assess the variation of climatically suitable areas for 40 alien plants. We developed a Potential Area Change Index and used it as the response variable in modelling for three future emissions scenarios and three global circulation models over three time periods. The area of origin and biogeographic province in Spain were also considered.

Results: We found a highly specific response for each plant species rather than a clear trend for the entire set of species. Predicted climate suitability increased over higher emission scenarios and longer projected time lags. Neotropical species showed the greatest potential climatic range expansion. We detected a strong interaction between the geographic origin of a species and the biogeographic province.

Conclusions: Special attention should be given to the areas where aridification of climate is projected and where introduced neotropical species are likely to expand their range. Future work should develop accurate species-specific approaches that allow the management invasive plant species.     

The role of forest residues in the accounting for the global warming potential of bioenergy

Bioenergy makes up a significant portion of the global primary energy pie, and its production from modernized technology is foreseen to substantially increase. The climate neutrality of biogenic CO₂ emissions from bioenergy grown from sustainably managed biomass resource pools has recently been questioned. The temporary change caused in atmospheric CO₂ concentration from biogenic carbon fluxes was found to be largely dependent on the length of biomass rotation period. In this work, we also show the importance of accounting for the unutilized biomass that is left to decompose in the resource pool and how the characterization factor for the climate impact of biogenic CO₂ emissions changes whether residues are removed for bioenergy or not. With the case of Norwegian Spruce biomass grown in Norway, we found that significantly more biogenic CO₂ emissions should be accounted towards contributing to global warming potential when residues are left in the forest. For a 100‐year time horizon, the global warming potential bio factors suggest that between 44 and 62% of carbon‐flux, neutral biogenic CO₂ emissions at the energy conversion plant should be attributed to causing equivalent climate change potential as fossil‐based CO₂ emissions. For a given forest residue extraction scenario, the same factor should be applied to the combustion of any combination of stem and forest residues. Life cycle analysis practitioners should take these impacts into account and similar region/species specific factors should be developed.     

Influence of age on the bioaccumulation of heavy metals in Apodemus sylvaticus at Merja Zerga lagoon,Morocco

The influence of age and sex on the bioaccumulation of heavy metals in Apodemus sylvaticus was studied in Merja Zerga lagoon in northern Morocco. Five trace metal elements (Zn, Pb, Cr, Cu and Fe) were quantitatively analyzed by Varian AA 240 atomic absorption spectroscopy with graphite furnace in three organs (Liver, Kidney and Heart) from animals of different age and sex. The maximum metal level of the analyzed samples was recorded in adults and was limited to 46.62 μg/g for Pb and 35.1 μg/g for Cu, while it reached 22.69 μg/g, 7.59 μg/g and 6.78 μg/g for Cr, Zn and Fe, respectively. Highly significant differences were found for bioaccumulation of heavy metals according to animal ages and no significant differences were observed between the two sexes among the studied animals. Our results revealed also the existence of a strong correlation (r > 0.65) between the majority of biometric parameters and the trace element concentrations. In general, we found that age is a critical factor in estimating the level of heavy metal pollution. Other characteristics such as habitat, feeding habits and anti-predator behavior of the species need to be studied.     

Least significant changes and monitoring time intervals for high-resolution pQCT-derived bone outcomes in postmenopausal women

Background:

Least Significant Change (LSC) assists in determining whether observed bone change is beyond measurement precision. Monitoring Time Interval (MTI) estimates time required to reliably detect skeletal changes. MTIs have not been defined for bone outcomes provided by high resolution peripheral quantitative computed tomography (HR-pQCT). The purpose of this study was to determine the LSCs and MTIs for HR-pQCT derived bone area, density and micro-architecture with postmenopausal women.

Methods:

Distal radius and tibia of 33 postmenopausal women (mean age: 77, SD: ±7 years), from the Saskatoon cohort of the Canadian Multicentre Osteoporosis Study (CaMos), were measured using HR-pQCT at baseline and 1-year later. We determined LSC from precision errors and divided them by the median annual percent changes to define MTIs for bone area, density, and micro-architecture.

Results:

Distal radius: HR-pQCT LSCs indicated a 1-8% observed change was needed for reliable monitoring of bone area and density while a 3-18% change was needed for micro-architectural measures. The longest MTIs (>3 years) pertained to cortical and trabecular area and density measures, cortical thickness and bone volume fraction; the shortest MTIs (~2 years) pertained to bone micro-architectural measures (trabecular number, thickness, separation and heterogeneity). Distal tibia: LSCs indicated a <1-5% observed change was needed for reliable monitoring of bone area and density, while a 3-19% change was needed for micro-architectural measures. The longest MTIs (>3 years) pertained to trabecular density, bone volume fraction, number, separation and heterogeneity; the shortest MTIs (~1 year) pertained to cortical and trabecular area, cortical density and thickness.

Conclusion:

MTIs suggest that performing HR-pQCT follow-up measures in postmenopausal women every 2 years at the distal radius and every 1 year at the distal tibia to monitor true skeletal changes as indicated by the LSCs.