Partitioning tree water usage into storage and transpiration in a mixed forest

Abstract

Background Water migration and use are important processes in trees. However, it is possible to overestimate transpiration by equating the water absorbed through the plant roots to that diffused back to the atmosphere through stomatal transpiration. Therefore, it is necessary to quantify the water transpired and stored in plants. Method The δ2H/δ18O technique and heat ratio method were used to explore the water usage of coniferous and broad-leaved tree species, including the proportions of water used for transpiration and water storage. Results Platycladus orientalis and Quercus variabilis had strong plasticity in their water usage from different sources. Platycladus orientalis primarily used groundwater (30.5%) and the 60–100-cm soil layer (21.6%) throughout the experimental period and was sensitive to precipitation, absorbing water from the 0–20-cm layer (26.6%) during the rainy season. Quercus variabilis absorbed water from all sources (15.7%–36.5%) except from the 40–60-cm soil layer during the dry season. In addition, it did not change its water source but increased its groundwater uptake during the rainy season. The annual mean water fluxes of P. orientalis and Q. variabilis were 374.69 and 469.50 mm·year− 1, with 93.49% and 93.91% of the water used for transpiration, respectively. However, nocturnal sap flow in P. orientalis and Q. variabilis was mainly used for water storage in the trunk rather than transpiration, which effectively alleviated drought stress and facilitated the transport of nutrients. Conclusions The water stored in both species comprised 6%–7% of the total water fluxes and, therefore, should be considered in water balance models.

Adsorption of Cadmium by Brassica juncea (L.) Czern. and Brassica pekinensis (Lour.) Rupr in Pot Experiment

“…Cd-contaminated soil concentrations of 5 and 20 mg Cd kg −1 were selected because they were beneficial to plant growth with a high BCF value. In addition, these two Cd concentrations have been reported as common Cd-contaminated levels in the Dabao mountain area in Guangdong province, China [10]. The model calculation shows that B. pekinensis is more effective than B. juncea to clean up soil with either an initial concentration of 5 or 20 mg Cd kg −1 .…”

“…In order to better simulate the adsorption of heavy metals by plants under natural environmental conditions, a pot culture experiment was conducted at seven soil levels (D.W) (5,10,20,40,60, 80 and 100 mg kg −1 of Cd) by applying non-polluted agriculture soil spiked with a CdCl 2 •2.5 H 2 O solution and an unamended control for comparison. We sprinkled the solution into the soil and left it for a month for equilibration.…”

“…As a widely cultivated and widely sold vegetable, the annual sales of Brassica juncea in China was 1.5 billion yuan. Brassica juncea has been considered a plant with great potential for phytoremediation [10]. In our previous report, it was found that another Brassica species, Brassica pekinensis.…”

“…There are two main kinds of optional plants used in phytoextraction. One has relied on the use of plants known as hyperaccumulators, such as the Zn/Cd hyperaccumulator Thlaspi caerulescens [7][8][9] and Arabidopsis halleri L. [10], with a recognized ability of Zn or Cd phytoextraction. However, herbaceous plants grow slowly and remain small in order to be preserved longer [3].…”

Sap Flow Velocity in Fraxinus pennsylvanica in Response to Water Stress and Microclimatic Variables

“…In addition, global climate observations demonstrated that land warms faster at night than during the day, and this trend can lead to an increase in plant water requirement at night ( Zeppel et al, 2015 ). The nighttime sap flow movement in plants can facilitate the transport of nutrients and oxygen for plant growth, which in turn affects plant growth status and productivity ( Chen et al, 2020b ; Liu et al, 2021 ).…”