Core Ideas: High doses of biochar increased water retention of sandy soil in both dry and wet conditions. Larger sized biochar decreased water retention at field capacity (FC). High‐pyrolysis biochar could increase water retention at FC and in dry conditions. We investigated the impact of biochar application on the evaporation rate of sandy soil. Knowledge of soil hydraulic properties under dry (below permanent wilting point) and wet (from saturation to permanent wilting point) conditions is helpful for evaluating soil physical quality and modeling the movement of the substances (water and nutrients) in biochar‐amended soils. To investigate the effect of biochar application on hydraulic properties of sandy soil under dry and wet conditions, water retention in wet conditions and soil drying curves from wet to dry conditions were measured under different application rates (1, 3, and 5%, w/w), particle sizes (<0.25, 0.25–0.5, 0.5–1, and 1–2 mm), and pyrolysis temperatures (300, 450, and 600°C) of wheat ( Triticum aestivum L.) straw‐derived biochar. Results showed that when higher rate biochar (3 and 5%) was applied into the sandy soil, water retention became higher under dry and wet conditions. Biochar application with a larger particle size (0.5–1 and 1–2 mm) increased water retention under saturation and dry conditions but decreased water retention at field capacity. Sandy soil amended with biochar at the higher pyrolysis temperatures (450 and 600°C) had higher water retention under field capacity or dry conditions. Increasing biochar application rate, particle size, and pyrolysis temperature decreased the evaporation rate of sandy soil under dry conditions. Our findings suggested that hydraulic properties of the sand–biochar mixture were mainly determined by biochar properties under dry conditions and were highly related to the interpores between particles under wet condition.

As a widespread direct effect of global warming, drought is currently wreaking havoc on terrestrial ecosystems' structure and function, however, the synthesized analysis is lacked to explore the general rules between drought changes and main functional factors of grassland ecosystems. In this work, meta‐analysis was used to examine the impacts of drought on grassland ecosystems in recent decades. According to the results, drought greatly reduced aboveground biomass (AGB), aboveground net primary production (ANPP), height, belowground biomass (BGB), belowground net primary production (BNPP), microbial biomass nitrogen (MBN), microbial biomass carbon (MBC) and soil respiration (SR), and increased dissolved organic carbon (DOC), total nitrogen (TN), total phosphorus (TP), nitrate nitrogen (NO3⁻‐N), and the ratio of microbial biomass carbon and nitrogen (MBC/MBN). The drought‐related environmental factor mean annual temperature (MAT) was negatively correlated with AGB, height, ANPP, BNPP, MBC, and MBN, however, mean annual precipitation (MAP) had positive effect on these variables. These findings indicate that drought is threatening the biotic environment of grassland ecosystem, and the positive steps should be taken to address the negative effects of drought on grassland ecosystems due to climate change.

Temperature and precipitation are expected to increase in the forthcoming decades in the northeastern Qinghai-Tibetan Plateau, with uncertain effects of their interaction on plant and soil carbon:nitrogen:phosphorus (C:N:P) stoichiometry in alpine ecosystems. A two-year field experiment was conducted to examine the effects of warming, precipitation increase, and their interaction on soil and plant C:N:P stoichiometry at functional groups and community level in an alpine meadow. Warming increased aboveground biomass of legumes and N:P ratios of grasses and community, but did not affect soil C:N:P stoichiometry. The piecewise structural equation model (SEM) indicated that the positive effect of warming on community N:P ratio was mainly resulted from its positive influence on the aboveground biomass of functional groups. Precipitation increase reduced C:N ratios of soil, grasses, and community, indicating the alleviation in soil N-limitation and the reduction in N use efficiency of plant. SEM also demonstrated the decisive role of grasses C:N:P stoichiometry on the response of community C:N:P stoichiometry to precipitation increase. The interaction of warming and precipitation increase did not alter plant community and soil, N:P and C:P ratios, which was resulting from their antagonistic effects. The stable soil and plant community C:N:P stoichiometry raised important implications that the effect of warming was offset by precipitation increase. Our study highlights the importance of considering the interaction between warming and precipitation increase when predicting the impacts of climate change on biogeochemical cycles in alpine meadow ecosystems.