Water utilization of typical plant communities in desert steppe, China

Abstract

Water is a limiting factor in the restoration and construction of desert steppe. Exploring plant water sources is necessary to understand soil-plant interactions and species coexistence; however, water sources of major plant communities within the desert steppe of Ningxia Hui Autonomous Region, China remain poorly understood. In this study, we analyzed the water uptake of plants in four typical communities: Agropyron mongolicum Keng.; Sophora alopecuroids Linn.; Stipa breviflora Griseb., and Achnatherum splendens (Trin.) Nevski communities. Stable isotopes δD and δ 18 O in the xylem of plant and soil water at different soil depths were analyzed. An IsoSource model was used to determine the soil depths from which plants obtained water. Results showed that A. mongolicum community obtained water predominantly from 0-20 and 40-80 cm depth, S. alopecuroids community from 0-20 cm depth, S. breviflora community from 0-40 cm depth, and A. splendens community from 0-20 and 80-140 cm depths. S. alopecuroides had a wider range of soil depths for water extraction, i.e., utilizing different water sources depending on habitat, and the plasticity of its water uptake pattern determined its role in different communities. Water source of plants relayed heavily on the distribution of their roots. Competition for soil water exists between different plant life forms in the sierozem habitat (A. mongolicum, S. alopecuroids, and S. breviflora communities), and in the sandy soil habitat (A. splendens community). The use of soil water by A. splendens community is more spatially differentiated, and shrubs and herbs can coexist stably. Under the pattern of extended drought period in the future, sierozem habitat may be more favorable for the formation of a dominant monoculture community type of perennial fibrous plants. In aeolian sandy soil habitat, A. splendens had a strong competitive advantage, and the growth of shallow-rooted plants was easily suppressed.

Water use characteristics of coexisting sand‐binding vegetation in two typical soil habitats in the desert steppe of China

“…Notably, over 60% of this rainfall occurs during the wet season from July to September (Yang et al, 2019). The average annual temperature is 8.1 C, with a significant seasonal difference of 28 C difference (Chen et al, 2022). Groundwater levels fluctuate between 3 and 8 m (Hu et al, 2021).…”

“…Table A.1 shows the physical properties at different soil depths under the four plant species within two soil habitats. The vegetation in this area is characterized by mosaic distribution patterns of artificially planted tall woody plants intermixed with natural low herbs (Chen et al, 2022;Song et al, 2018) In the open area next to the research plot, an automatic weather station with a Delta-T logger (Delta-T Devices Ltd., UK) was established, collecting meteorological data on precipitation and air temperature at 10-min intervals. The meteorological data reported in this study are daily averages.…”

Analysis of Vegetation Dynamics and Driving Mechanisms on the Qinghai-Tibet Plateau in the Context of Climate Change

“…Furthermore, the structure of the regional desert ecosystem was relatively simple. The diversity of biological species was low, the self-regulation ability was weak, the antidisturbance ability was poor, and the ecosystem was fragile [66]. When the annual mean precipitation gradient was Level 2, the main factor affecting vegetation changes was annual mean precipitation (X 1 ).…”

“…Actual evaporation replaces mean annual precipitation as the factor with the highest explanatory power for vegetation evolution in low precipitation areas. These areas lack sufficient precipitation to support the water requirements for vegetation growth, with water primarily sourced from nearby river systems [66,70]. The main vegetation type is Desert, which has weak self-regulation ability and a fragile ecosystem.…”

Plant biotype interacting grazing activity shapes grassland ecosystem functions

“…As grasses grow, the dominant plants shift from sedge to forbs species in alpine meadow, whereas graminoid species shift to forbs in alpine steppe (Peng et al, 2020), and the intensity of the shift can vary with anthropogenic disturbances, such as grazing activity (Hao et al, 2021). In contrast, soil-plant interactions and species coexistence in both desert and typical steppes are mainly affected by water availability (Chen et al, 2022). Precipitation in July and August plays a critical role in driving net primary productivity of grasslands in the typical to desert steppe transition zone (Lv et al, 2022).…”