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A plantation of 5-year-old poplar Populus × euramericana cv. ‘Neva’ was used to study the regulatory effects of root pruning on nutrients, photosynthetic characteristics, and water-use efficiency (WUE) of leaves and growth rates of diameter at breast height (DBH; 1.3 m), tree height, and volume. Six root-pruning treatments were conducted with different combinations of intensity (at a distance of six, eight or ten times DBH from the trunk) and orientation (on two or four sides of the trees). Results showed that the N, P, K, photosynthetic rate, transpiration rate, and stomatal conductance of leaves were all significantly decreased by root pruning over the initial period following root pruning (30 days), but increased in the subsequent investigations. The values of the above indexes peaked in 8–2 treatment (i.e., eight times DBH distance on two sides). The leaf WUE in 8–2 treatment, and average growth rates of DBH, tree height and volume, were the highest among all treatments within 3 years of root pruning. The results indicated that the root pruning based on the appropriate selection of intensity and orientation had significant positive effects on leaf nutrients, photosynthesis, and growth of trees in a closed-canopy poplar plantation.

This study aimed to determine the effects of root pruning on the physicochemical characteristics and microbial activities of poplar rhizosphere soil. The root systems of 5-year-old poplar (Populus×euramericana cv. ‘Neva’) trees were manually pruned at 6, 8, or 10 times diameter at breast height (DBH) from the trunk (severe, moderate, and light, respectively) along both inter-row sides. Moderate root pruning significantly increased the concentrations of amino acids, organic acids, and total sugars in the root exudates and decreased the pH of rhizosphere soil. This treatment also increased the contents of available nitrogen, phosphorus, potassium, and total organic carbon as well as high-, medium-, and low-activity organic carbon in rhizosphere soil. Moreover, moderate pruning increased the contents of microbial biomass carbon and nitrogen, and enhanced basal respiration, in addition to decreasing the metabolic quotients in rhizosphere soil by 8.9%, 5.0%, and 11.4% compared with control, light, and severe root pruning treatments, respectively. Moderate pruning increased the growth rates of DBH, tree height, and volume to the highest levels. Furthermore, these indices were not significantly different between the light root pruning and control groups, but varied significantly between severe and moderate root-pruning treatments. Thus, root pruning, depending on the distance from the trunk, significantly influences the physicochemical properties and microbial activities in poplar rhizosphere soil.

The biomass cellulose nanocomposite membrane is regarded as one of the most promising adsorbents for resource recovery and pollution control owing to the unique physicochemical properties. Herein, a recyclable biomass cellulose–CeO2 nanocomposite membrane (BCCM) is fabricated by in situ growth of CeO2 on the cellulose membrane (CM) surface and then employed for the elimination of fluoride from industrial wastewater. Structural characteristics of the BCCM were characterized by XRD and SEM. The adsorption experiment indicated that the maximum fluoride adsorption capacity of the BCCM was 48.0 mg/g. Kinetic and isotherm results elucidated that multilayer chemisorption dominated the BCCM adsorption process. Besides, the adsorption mechanism was also investigated by the energy-dispersive X-ray, FT-IR, and XPS analysis. More importantly, the BCCM has strong acid–base adaptability and can be used in extreme environments. This work provides an effective and environmentally friendly strategy to prepare other biomass nanocomposite membranes, which shows great potential for environmental remediation and chemical separation.

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