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According to IPCC high elevation areas are highly vulnerable to climate change. Since these ecosystems have a considerable carbon stock, it is crucial to investigate the influence of extreme climate conditions such as drought on net ecosystem CO2 fluxes (NEE), the difference between the two components gross primary production (GPP) and ecosystem respiration (Reco). Grasslands cover 20–30% of Swiss landscapes and have a significant carbon stock of about 11% (of total carbon stock of Switzerland according to Bolliger et al. (2008)). However, relative changes in GPP and Reco can transform an ecosystem from a net carbon sink to a net carbon source to the atmosphere, especially under changing environmental conditions. In this study, we aim to understand the impact of extreme summer drought on NEE and evapotranspiration of a Swiss alpine grassland by comparing the year 2018 to the preceding 3-year period. In addition, we studied the influence of a change in snow cover on winter fluxes as an important indicator of climate change. To perform this study, we used continuous eddy covariance data measured for about 4 years at Crap Alv (Alp Weissenstein, CH-AWS, Swiss Fluxnet) located at 2000 m a.s.l. in the Grisons, eastern Switzerland. The site is grazed in summer for about three months from mid-June to mid-September and thus is extensively managed. We hypothesize that the extreme 2018 summer drought reduced carbon uptake while increasing ecosystem respiration and therefore reduced the capacity of the grassland for net CO2 uptake. Bolliger, J., Hagedorn, F., Leifeld, J., Böhl, J., Zimmermann, S., Soliva, R., Kienast, F., 2008. Effects of land-use change on carbon stocks in Switzerland. Ecosystems 11: 895–907. [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]

The arid and semi-arid ecosystems plays an important role in the terrestrial carbon cycle, but the dynamics of the carbon cycle are not clear while climate changes. Based on the TECO-R model for desert steppe, we estimate one of the most sensitive grassland types in arid and semi-arid ecosystems, desert steppe, Inner Mongolia, with its magnitude, distribution and dynamics of different carbon pools from 2000 to 2017, and the relationship between its changes with environmental factors. The results showed that the average carbon density of ecosystem was 2.51 kg C per square meter, of which the soil accounted for 91.8%. The carbon storage was significantly different among different vegetation biomes, the grassland dominated biome was higher than the shrubland biome, which were 2.85 and 2.19 kg C per square meter, respectively. During the period of study, the carbon sequestration with an annual average of 3.09 Tg C per year. Among the environmentally influencing factors of carbon dynamics, precipitation is the most significant control factor, while temperature has an opposite effect on carbon sequestration, especially for soil carbon pools. The temperature of whole region was widely increased, but the average annual precipitation was relatively stable, making the drought a major limiting factor for the increase of carbon sink capacity in the region. However, in the non-growth season, the precipitation and the temperature were increasing at 0.27 mm per year and 0.055 °C per year respectively, the tendency weakens the negative effects of increased temperature and drought in the growing season on carbon sequestration, and is a major natural contributor to the stabilization of carbon sinks in the desert steppe. [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]