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Partitioning evapotranspiration ( ET ) into soil evaporation ( E a ) and plant transpiration ( T r ) is important to understand response of ecosystem water balance to climate warming. A field experiment was conducted to investigate the effect of additional infrared radiation as a simulation of climate warming (W1: 130 W m −2 and W2: 150 W m −2 ) on ET , E a , T r , and soil moisture in an alpine meadow in the Qinghai-Tibet plateau (QTP). ET was calculated by using an energy balance model and a soil moisture correction function. E a in warm-rainy season was estimated by a multiple linear regression with latent heat, soil moisture in 0–10 cm layer and soil temperature in 20 cm depth as independent variables. T r was quantified as the difference between ET and E a . Results showed that annual ET increased by 92 mm and 89 mm, annual E a increased by 29.12 mm and 33.37 mm, and annual T r increased by 63.53 mm and 55.81 mm in W1 and W2 treatments, respectively. The results suggest that T r stimulation accounts for most of the ET change and is the major reason for the soil surface layer drying in alpine meadow ecosystem on the QTP. [ABSTRACT FROM AUTHOR]

Climate warming and heavy livestock grazing are known to have great impacts on alpine ecosystems. However, it is still unclear how plant belowground biomass, soil carbon, and nitrogen respond to climate warming and heavy livestock grazing at different soil depths in these alpine ecosystems. The aim of this research was to investigate the individual and combined effects of warming and clipping on plant and soil properties in an alpine meadow ecosystem. Here, we report the results from a manipulation experiment, which has been running in the Qinghai-Tibetan Plateau (QTP) since 2010. Infrared radiators were used to simulate year-round warming starting in July 2010, while clipping was performed once a year in October to mimic the local heavy livestock grazing beginning from 2011. The experiment, including 3-year warming and 2-year clipping, was a randomized block design which consisted of five replications and four treatments: control (CK), warming without clipping (W), clipping without warming (C), and warming combined with clipping (W × C). Plant and soil properties were determined in the growing season of the alpine meadow in 2012 and 2013. The W treatments induced the downward transport of soil moisture to deeper layers. The drought caused by the downward transport of soil moisture in upper layers altered the allocation of plant belowground biomass at various soil depths. The relative effects on plant belowground biomass, organic carbon, activated carbon, and total nitrogen were also observed in deeper soil layers in W, C, and W × C. Therefore, the allocation of plant belowground biomass to deeper layers likely modified the distribution of organic carbon, activated carbon, and total nitrogen in soil of the alpine meadow in the QTP. [ABSTRACT FROM AUTHOR]