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Large part of Eastern Siberia is covered by permafrost and is accessible only by rivers in summer and ice roads in winter. They critically depend on ice formation dates and thickness. Ground thawing, subsidence, thermokarst and other hazardous cryogenic processes could lead to failure of infrastructure. The study aimed at assessment of current and future climate-induced changes of river ice and active layer depth in Central Yakutia. Hydrological models Hydrograph and HYPE were employed to simulate active layer depth and river ice respectivelywith ensembles of bias-corrected CMIP5 climate model outputs (1971-2100) as forcing representing the emission scenarios RCP4.5 and RCP8.5.Air temperature in Yakutsk has increased from -10.4 °C (1951-1978) to -8.7 °C (1979-2012). It is expected to further increase by 3.5°C and 6.6°C according to RCP4.5 and RCP8.5 by the end of XXI century. The mean ice thickness of the Lena River at Yakutsk in March and April has decreased in March and April during the period 1955-2015 by 20-35%. River breakup is shifting to earlier dates at a rate of 1.2 days per decade (1939-2015). Ground temperature and thawing depth are relatively stable for the period 1982-2012.Hydrograph model was applied in a lumped way to simulate active layer depth. The dominant landscapes in Central Yakutia are larch forest with sandy soil, pine forest with sandy soil, larch forest with loamy soil, alas depressions covered by grassland with loamy soil, inter-alas areas covered by larch and birch forests, and marsh. Model parameters were estimated based on field data that is representative for above-mentioned landscapes. Validated on the historical observations Hydrograph model was used for future projection. According to RCP4.5 practically no changes of active layer depth are expected in alas and interalas areas. Deepening of active layer in marshes, pine and larch forests with sandy soils for period 2071-2100 would reach 47-66 cm comparative to 2011-2040. According to extreme RCP8.5 scenario permafrost would completely thaw in upper 5 m in three landscapes with sandy soils while thawing depth would increase only by 15-27 cm in other three landscapes with loamy soils. Simulation results suggest relatively high resilience of alas, interalas areas and larch forests with loamy soils to future warming.The Arctic-HYPE model was applied to simulate ice depths and freeze-up and break-up dates at river ice road crossings in the Lena, Aldan and Viluy rivers. Local observations from the Lena river at Tabaga, Yakutsk and Khangalassy were used for critical model improvements. Projections towards the end of XXI century under RCP4.5 and RCP8.5 suggests that the ice cover period is likely to be one month shorter than today, both through earlier break-up and later ice formation dates, and reduction of annual maximum ice depth would be in the range 40 to 70 cm. [ABSTRACT FROM AUTHOR]

Ecosystem services (ES) play an important role in sustaining ecological security, sustainable development and human well-being. Located in the north of Beijing city, the Xilin Gol grassland of Inner Mongolia is vital importance in safeguarding ecological safety and sustainable development of Beijing and the neighboring areas. This study investigated spatio-temporal changes of four critical ES in the Xilin Gol grassland from 1990 to 2016, including net primary productivity (NPP), water yield (WY),soil conservation (SC) and soil loss due to wind (SL), by incorporating multiple data and four widely used biophysical models (CASA, InVEST, USLE and RWEQ). Additionally, the constraint relationship between paired ES was determined by extracting the upper constraint lines from the two-dimensional scatter plots. Research findings indicated that during 1990-2016, NPP fluctuated between years. The amount of WY and SC decreased significantly in 1990-2001(the year of 2001 is the time node for the implementation of ecological restoration project), but slightly enhanced in 2001-2016. SL increased significantly in 1990-2001, but showed a significant downward trend in 2001-2016. Spatially, four ES exhibited significantly spatial heterogeneity. From 2001 to 2016,vegetation restoration(mainly in conjunction with ecological restoration programs),increasing rainfall and the reduction in wind speed produced positive effects on NPP, WY, SC enhancement and SL reduction. With respect to ES constraint line analysis, there was a hump-shaped constraint effect between NPP and SC. In general, the higher NPP amount, the better vegetation growth. Vegetation could effectively inhibit water erosion. As water was the main limiting factor for vegetation growth in the Xilin Gol grassland. Accompanied by the increase of rainfall, NPP also enhanced. When NPP amount exceeded a certain threshold, higher NPP meant more local precipitation, which increased the possibility of water erosion. The gradually increasing constraint effect of higher NPP on WY indicated that, in Xilin Gol grassland, improving NPP might decrease WY. The constraint line method was used to explore the relationships of ES, which could enrich our understanding of interaction between ES and potential influence factors. [ABSTRACT FROM AUTHOR]

African wetlands in arid and semi-arid regions provide a multitude of ecosystem services andhave been described as the "heart of Sahelian life systems". The Khor Abu Habil alluvialwetlands (Khor is the name given to ephemeral rivers in Sudan) are situated in thesemi-arid zone in the southern part of the Sudan. These ephemeral wetlands are fedby seasonal wadi streams and remain for several months. They provide a habitatfor migratory water birds and play a fundamental role in supporting the humanpopulation (agriculture, grazing, fishing, hunting and construction). In this study weanalyse the Land Use and Land Cover (LULC) dynamics related to agriculturalactivities. We choose agriculture as an entry point because it is the main activity and themain LULC changing factor in the study area. A questionnaire and semi-structuredinterviews were conducted in the study area, documenting different agriculturalactivities and land uses. Additionally, remote sensing data and field data on LULC werecollected and analysed with Google Earth Engine, R and GIS software. Differenttypes of agriculture are practised depending on the soil type. The agriculture inthe wadi pathways depends on floods and the agriculture on the wadi banks is arain-fed. Accordingly, two agricultural calendars were created, namely a rain-fedagricultural calendar and a flood-depending one. Additionally maps illustrating the LULCchange over a year were created. The results helped us to understand the annualchanges in the LULC between the classes agriculture, vegetation, grassland, water andbare soil. Indeed, the same piece of land may be a grassland used by pastoralists aswell as an agricultural land used by farmers, depending on the period of the year.This is a challenge for the creation of classical LULC maps. Wadis or Khors areparticular ecosystems that occur in semi-arid regions. In our study area, the economicactivities show a relationship between land uses and different human communities: theagriculturalists and the pastoralists, who live in synergy with the natural cycles of the seasonsand the wadi waters. The agricultural activities and the different LULC classes aredynamic and vary over the year depending on the wadi flood waters. This characteristicdistinguishes the Khor Abu Habil ecosystem from other ecosystems where LULC classesremain stable most of the year. Our research is part of the FAO-supported projectRESSOURCE with the overall goal to localise and study wetlands of internationalimportance in the sub-saharan Africa and declare them as Ramsar protected zones. [ABSTRACT FROM AUTHOR]

Roots play a key role in plant anchorage, absorption and storage of soil resources (water, nutrients, carbohydrates) and biogeochemical cycles in terrestrial ecosystems. Studying the configuration of the root system and its distribution in the underground space is critical to understanding these effects of the root. For nearly two decades, ground penetrating radar (GPR) has been used as a non-destructive geophysical method to describe the spatial distribution of coarse roots under controlled conditions and field conditions. The detection effect of the ground penetrating radar on the root system depends mainly on the frequency of the radar antenna used and the degree of difference in the relative dielectric constant (ε) between the root and the soil. Nevertheless, the relative permittivity of soil varies greatly between summer and winter due to the effects of seasonal frozen soil. Using this seasonal variation, we evaluated the use of GPR with 900 MHz and 400 MHz antennas to nondestructively delineate the spatial distribution of the roots system of the same shrubs both in summer (August) and winter (January of the second year) under field conditions in the Xilingler shrub grassland ecosystem in Inner Mongolia, China. In summer, the relative dielectric constant difference between root and soil is greater due to the high water content of the roots, and more root signals can be obtained. However, as the soil moisture content is also high, the electromagnetic wave decays faster, which limits the detection depth of the radar, and only the shallow root signals were obtained. In winter, because of the existence of shallow frozen soil, the relative dielectric constant of the soil is low, which is conducive to the penetration of electromagnetic wave into the deep soil, so deeper root information can be obtained. However, the water content of roots will decrease due to the influence of low temperature, which resulting in a smaller difference in the relative dielectric constant between roots and soil. Therefore, the recognition effect on the shallow root system is relatively poor compared with results obtained in summer. Combined with the detection results of the two antenna frequencies (900MHz and 400MHz) in summer and winter, wealth and complete information of shrub root system distribution can be obtained. An effective GPR-based root measurement strategy is proposed by making full use of the seasonal changes of soil environment, which can further enhance the application of GPR in plant root research. [ABSTRACT FROM AUTHOR]

Agricultural productivity and food security depends on the application of nitrogen (N) fertilizers. Since the use of N fertilizers has increased, it allowed the world population to increase from 3 to well over 7 billion while food and feed production from arable systems increased by 45–70% since 1950. The excessive use of N fertilizers causes harmful effects to the environment, e.g. increased emissions of nitrous oxide (N2O), nitric oxide (NO), ammonia (NH3) to the atmosphere and leaching of nitrate (NO3) into water bodies. Combined with climate change (temperature increase and precipitation change) will further impact agricultural productivity and N losses. Within the "NITROAUSTRIA" project grassland productivity and associated nitrous oxide (N2O) emissions from Austrian grassland soils were simulated using the LandscapeDNDC model. Five different regions and six different soil types covering more than 70% of intensively managed grassland area in each region were simulated. The objectives of this study were to predict productivity from intensively managed grasslands and associated N2O fluxes under present and future climate change conditions. The baseline scenario (2005 to 2014) compares grassland productivity and N2O fluxes for the five different regions. It proved N2O emission strengths to be higher than emissions from adjacent croplands. For future climate change impact assessment the stochastic weather generator LARS-WG was used. LARS-WG projects local time series of observed weather (temperature, precipitation and radiation) with climate change models. For all five regions, climate change scenarios were generated for RCP4.5 and RCP8.5 covering the time periods 2021-2040, 2041-2060 and 2061-2080. The results of the climate change ensemble simulations indicate that increased temperature will increase grassland productivity in the investigated regions. Even under RCP8.5 conditions, all regions will sustain increasing productivity due to prolonged vegetation periods and higher temperatures. Changed precipitation patterns and increased plant nitrogen uptake will further decrease NO3- leaching in grassland soil. Peak N2O emissions are mainly responsible for high annual fluxes and magnitude and frequency of these peaks may increase in the future. The project revealed the importance of the grassland management to be superior to determine the N2O emissions and NO3- leaching in grassland soil rather than the impacts of future climate change. [ABSTRACT FROM AUTHOR]