Soil Water Use Strategies of Dominant Tree Species Based on Stable Isotopes in Subtropical Regions, Central China

Abstract

Water is a crucial factor affecting plant growth and ecosystem processes. In the subtropical region, global climate change leads to frequent seasonal droughts. How plant water strategies and the adaptability of forest ecosystems change is an urgent issue to be discussed. In this study, four sample plots (P. massoniana for Plot 1, C. lanceolata for Plot 2, Q. acutissima for Plot 3, C. funebris and I. corallina for Plot 4) were selected in the Taizishan Mountain area of Hubei, China, including three forest types (coniferous forest, broad-leaved forest and coniferous broad-leaved mixed forest) and five dominant tree species. The δD and δ18O isotope compositions in plant and soil water were analysed, and the water use strategies of dominant species were predicted by using the MixSIAR model. The water absorption depth and proportion of the five species were significantly different in different seasons. In plot 4, I. corallina and C. funebris derived (58.8 ± 14.0% and 55.7 ± 23.4%, respectively) water from 10–40 cm soil in wet season, but C. funebris shifted to derive water from deep soil in dry season. This result indicates that the mixing of C. funebris and I. corallina can effectively prevent water competition in dry season with water deficit. From wet season to dry season, the depth of water utilisation of the P. massoniana, C. lanceolata, Q. acutissima and C. funebris with deep roots converted from shallow to deep soil, suggesting that the four species had significant dimorphic root systems and strong ecological plasticity.

Variability in the Hydrological Processes of Six Typical Woodlands Based on Stable Isotopes in Subtropical Regions in Central China

“…The relationships between soil water 𝛿𝛿𝛿𝛿 and oxygen 𝛿𝛿 18 𝑂𝑂 isotopes in the Taizishan area are shown in Figure 11. The slope and intercept in the soil waterline equation were smaller than the atmospheric waterline equation 𝛿𝛿𝛿𝛿 = 8.01𝛿𝛿 18 𝑂𝑂+10.28 (R 2 = 0.97) [41].…”

“…After being sealed with Parafilm, the sample bottles were quickly placed in an insulated cabinet at a temperature of 0-5 • C (in the field) and then kept in a freezer at a temperature of −5 • C for a long time. The sampling time chosen was a day with no rainfall events occurring 3 days before to keep the soil moisture stable [41].…”

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

“…The excavation reached up to the depth of 200 cm (with root sampling intervals matching those of soil sampling intervals), and 108 root samples in total were collected (4 species × 9 depth intervals × 3 repetitions). Then, the samples were sorted by diameter: >5, 2–5, 1–2 and <1 mm (Li et al, 2022). Next, the roots experienced the 48‐hour oven‐drying at 70°C, after which their weights were measured to determine biomass and distribution within each soil layer.…”

“…Then, the samples were sorted by diameter: >5, 2-5, 1-2 and <1 mm (Li et al, 2022). Next, the roots experienced the 48-hour oven-drying at 70 C, after which their weights were measured to determine biomass and distribution within each soil layer.…”

Using Isotopic Labeling to Investigate Artemisia ordosica Root Water Uptake Depth in the Eastern Margin of Mu Us Sandy Land

“…Such man-made or natural differences provide a material basis for studying the water use strategies of plants. By using these differences, the water use strategies of plants in different species, regions, and seasons are revealed [35][36][37][38][39][40]. Because the vadose zone is an important source of plant water in the arid region, understanding the range of plant water sources in the arid region is of great significance for studying the water cycle process and soil-vegetation-atmosphere exchange process in the arid region.…”