Sap flow and plant water sources for typical vegetation in a subtropical humid karst area of southwest China

Abstract

Plant water use plays a crucial part in the soil-plant-atmosphere continuum. However, in karst regions, plants frequently suffer from water shortages due to low soil water storage capacity. Therefore, it is necessary to understand plant water consumption (as determined by sap flow) and seasonal variation of water sources to improve water management in karst catchments. In this study, thermal dissipation probes (TDP), calibrated using empirical equations, were used to measure the sap flow of three typical woody vegetations, including Coriaria nepalensis (sparse-shrub), Toona sinensis (secondary forest) and Populus adenopoda (shrub-grass). Oxygen and hydrogen stable isotopes were used to analyze seasonal variation of plant water sources. The results showed that: (1) T. Sinensis (3.89 ± 3.87 LÁday −1) had significantly higher daily sap flow than C. nepalensis (0.33 ± 0.37 LÁday −1) and P. adenopoda (0.09 ± 0.12 LÁday −1); (2) daily sap flow was closely correlated to photosynthetically active radiation (PAR) and vapour pressure deficit (VPD); (3) over the entire study period, plants mainly used water from the surface soil horizons; and (4) a greater proportion of epikarst water was used for C. nepalensis than by T. sinensis and P. adenopoda over the whole growth stage, and more epikarst water was used in early and mid-growth stages compared to the late stage for the three species. This study contributes to a deeper understanding of the plant water use strategies in karst regions, and is helpful for ecosystem management.

Grain for Green Project May Not Threaten Ecosystem Sustainability by Degrading Water Availability in Humid Karst Landscapes

“…For different vegetation succession stages, the smallest ET is from cropland ( Zea mays + Brassica napus ), mainly result from that the planting density of Zea mays is smaller than that of grass to ensure high yield, and Brassica napus with high LAI grows in winter when PET is low (Figure S4 in Supporting Information ). While the secondary forest has the highest ET among all vegetation types, due to the large canopy and water uptake from the deep fractured bedrock (J. Y. Hu et al., 2021; Yang et al., 2014; Zeng et al., 2021). These variations of ET among vegetation types suggest that natural vegetation restoration increases ecosystem ET in the humid karst region, which is also similar to the findings in other non‐karst regions (Liu et al., 2013; Rohatyn et al., 2018; Twine et al., 2004; Zhang et al., 2011).…”

Using stable isotopes to investigate differences of plant water sources in subalpine habitats

“…Tiemuerbieke et al (2018) found that desert shrubs adapted their root systems in response to changes in soil water, which is one of the most important strategies for adapting to periodic water shortages. Zeng et al (2021) pointed out that typical shrubs in karst areas can transfer water from different sources during different times according to their dimorphic root systems. Ding et al (2018) found that Salix cupularis , Potentilla fruticosa , Rhododendron thymifolium , and Salix oritrepha change their water use strategies according to soil water content.…”

Haplotype-resolved genome assembly of Coriaria nepalensis a non-legume nitrogen-fixing shrub

“…C. nepalensis is a non-legume nitrogen-fixing plant that forms root nodules with the actinomycete Frankia 2 , 3 . The biological ability of nitrogen-fixation in this species contributes to its rehabilitation capacity of nutrient-poor degraded land 4 , 5 ; in combination with its osmotic adjustment function and drought tolerance 6 , 7 , C. nepalensis improves the abiotic conditions and provides more suitable habitat for associated plant species 8 – 10 . Furthermore, essential oils and extracts from C. nepalensis could be used as promising drugs due to their antimicrobial 11 , 12 and anti-convulsant activities 13 .…”