：Terrestrial ecosystem carbon storage is an important part of global carbon storage, and land use patterns are an important driver in the evolution of its carbon stock. The evolution of land use patterns is particularly evident within urban agglomerations. In this study, the Guanzhong Plain urban agglomeration was taken as the study area, and the CA-Markov simulation model and the InVEST carbon stock assessment model were used to simulate the evolution of land use patterns and carbon stocks in the study area under different scenarios for the last 20a (2000, 2005, 2010, 2015, 2020) and the next 10a (2030). In addition, a decoupling elasticity index model was coupled to reveal the link between land use conflicts and carbon stocks in the land use evolution process. The results show that: 1) From 2000 to 2030, the main land use types in the Guanzhong Plain urban agglomeration are cultivated field, woodland and grassland. In time, the type of evolution of land use types is mainly manifested in the decrease of cultivated field and the increase of construction land, and in space it is mainly manifested in the radial expansion of construction land to the periphery with Xi’an city as the centre. (2) Carbon stock in the Guanzhong Plain urban agglomeration continues to decrease from 2000 to 2030. And spatially, carbon stock shows a distribution trend of high on both sides and low in the middle. 3) The conversion of cultivated field to construction land is the most important reason for the decrease in carbon stock in the Guanzhong Plain urban agglomeration. 4) The decoupling relationship between the area of cultivated field occupied by construction land and carbon storage in the Guanzhong Plain urban agglomeration from 2000 to 2020 is in the order of recessive decoupling, strong decoupling, strong negative decoupling, and strong decoupling. From 2020 to 2030, the decoupling relationship between cultivated field occupied by construction land and carbon storage is strong decoupling. The cities that are strong decoupling in the natural and planning scenarios account for 25% and 50% of the total number of urban agglomerations respectively. The study can provide a pathway reference for land use restructuring and carbon stock enhancement of terrestrial ecosystems in the Guanzhong Plain urban agglomeration.

Vegetation plays an active role in soil water dynamics and water balance in atmosphere-soil-vegetation-groundwater system. Therefore, we characterised soil water transportation at depths of 0-4.0 m, induced by root water uptake of groundwater-dependent Salix across a whole growth stage, as well as taking place in non-vegetated soil, in the semi-arid Ordos basin of China. The results show that: soil moisture content showed clear heterogeneity under the combined influence of evaporation, rainfall and root water uptake. Thus, the soil profile was divided into the climate impacted layer, the transitional layer, and groundwater supporting layer. Root water uptake increased the variability of soil water in the vadose zone and changed the classification structure. The impacts of different rainfall regimes on soil moisture and vegetation response at the individual plant scale were systematically analysed. The rainwater infiltration hysteresis as connected to rainfall intensity, soil depth and the roots-system preferential channel were confirmed, as was the canopy-shading effect. Further, an exponential-logarithmic normal composite root water uptake distribution was obtained, via an inverse method. Of the accumulated 356.3 precipitation in 2016, the annual soil water increase was 97.9 mm for bare site, increased by 10.2% in total, accounting for 25.5% of the precipitation of that year. Conversely, for vegetated site, annual soil water decrease registered at 254.40 mm, decreased by 28.3% in total. The contrastive experiment indicates that root water uptake processes change the soil water flow field and aggravate water scarcity, resulting in soil desiccation in the deep local soil layers and groundwater depletion. The dried soil layers blocked water interchange, which is extremely detrimental to ecohydrological processes. Our results provide a scientific basis within which the hydrodynamic processes of vegetation in semi-arid regions may better be understood and inspire research to find a balance between groundwater management and vegetation replanting.