Huanchao Zhang

Understory vegetation control in intensively managed plantations can simultaneously reduce residue inputs and expose soils to herbicides, but their respective effects on forest-soil microbial functioning remain unclear. We combined field measurements across four understory tending regimes with a 30-day microcosm experiment manipulating vegetation-residue addition and glyphosate exposure. In the field, chemical tending increased soil bulk density and reduced total porosity in the 0–10 cm layer and altered micronutrient availability. In the microcosms, residue addition significantly increased soil organic matter (SOM) and microbial biomass carbon (MBC), whereas glyphosate exposure had little effect on SOM but reduced MBC by 15.24%–48.01% across corresponding residue levels. Residue addition generally increased bacterial and fungal alpha diversity and was associated with smaller compositional differences between glyphosate-exposed and unexposed communities under high-residue conditions. Residue addition and herbicide exposure produced distinct changes in microbial biomass, diversity, and community composition, while their interaction was not significant for MBC. Exploratory partial least squares path modeling suggested that SOM and MBC were associated with treatment-related microbial responses. Together, these findings show that organic resource supply and herbicide exposure exert contrasting short-term effects on soil microbial biomass and community composition.

Cadmium (Cd) contamination in soil poses serious environmental risks. Phytostabilization with fast-growing species like poplar offers a sustainable solution. The addition of soil organic amendments, including pig manure (PM), wheat straw (WS), and biochar (BC), may affect soil Cd availability and the phytoremediation efficiency of poplar. The results revealed that the order of dissolved organic carbon (DOC) content during poplar growth was PM > WS > BC > CK (without soil organic amendments). From the 8th week, the water-soluble Cd content in the soils treated with PM, WS, and BC was notably lower than that in CK (P < 0.05). After 4 months of poplar growth, compared with CK, the addition of soil organic amendments reduced the proportion of exchangeable Cd in the soil and increased the ratios of carbonate-bound, Fe–Mn-oxidized, organic-bound, and residual Cd in the soil. The poplar grew and adapted well to soil contaminated with Cd, as evidenced by the 100% survival rate. At each Cd level, the accumulation of Cd was highest in the roots compared to stems and leaves. Especially, compared with the other soil organic amendments, PM increased the dry biomass of the poplar to 4.86 ± 1.08 g and accumulated 0.31 ± 0.11 mg of Cd. These findings suggest that pig manure may serve as a low-cost and effective amendment for poplar-based phytostabilization in moderately to highly Cd-contaminated soils.

NaCl stress adversely affects plant growth. Tamarix ramosissima Ledeb (T. ramosissima), a halophyte, thrives in saline-alkali areas. Myo-inositol, a lipid-soluble compound, is crucial for stress response, but its role in mitigating NaCl damage remains underexplored. We analyzed transcriptome sequencing and metabolites in T. ramosissima roots under NaCl stress at various intervals (0 h, 48 h, and 168 h). We identified ten Myo-inositol oxygenase-related genes. Nine of these genes, linked to metabolic pathways involving Myo-inositol, showed differential expression. Myo-inositol accumulation increased over time, suggesting its role as an osmotic regulator and reactive oxygen species (ROS) scavenger. This accumulation likely shields T. ramosissima from NaCl-induced osmotic and oxidative damage. Notably, Unigene0002140 and Unigene0095980, associated with Myo-inositol oxygenase, appear to regulate Myo-inositol accumulation and correlate significantly with its levels. We hypothesize they are key genes in controlling Myo-inositol levels, warranting further study. This research illuminates the role of Myo-inositol oxygenase-related genes in T. ramosissima roots combating NaCl stress, offering insights for selecting salt-tolerant tree species.

In forest ecosystems, elevation gradient is one of the most influential factors on soil characteristics, vegetation types, and soil microorganisms. However, it remains unclear how the elevation gradient and the soil environment under its influence affect soil microbial communities under two distinct vegetation types. In this study, high-throughput sequencing technology from Illumina was utilized to examine the response of soil microbial communities to elevation and their driving factors in forests of Pinus taiwanensis and Pinus massoniana in various Jiangxi Province locales. The results demonstrated that the elevation gradients of the two pines had significant effects on soil organic carbon (SOC) and total nitrogen (TN), both in unimodal mode as well as on the alpha diversity of soil microbes. The community structure of soil bacteria is more sensitive to elevation than that of soil fungus. At different elevations in the two pine forests, Acidobacteria, Proteobacteria, Chloroflexi, Verrucomicrobia, Bacteroidetes, Patescibacteria, and Thaumarchaeota are the dominant bacterial phyla, and Ascomycota, Basidiomycota, and Mucoromycota are the dominant fungal phyla. This investigation revealed that SOC and TN were the two most influential factors on the alteration of the soil microbial community in two pine forests. In summary, there were substantial changes in soil microbial diversity and community composition across the two different pine forests, with elevation and soil characteristics (SOC and TN) serving as the primary drivers.

Emamectin benzoate (EMB) is a widely used pesticide and feed additive in agriculture and aquaculture. It easily enters the aquatic environment through various pathways, thus causing adverse effects on aquatic organisms. However, there are no systematic studies regarding the effects of EMB on the developmental neurotoxicity of aquatic organisms. Therefore, the aim of this study was to evaluate the neurotoxic effects and mechanisms of EMB at different concentrations (0.1, 0.25, 0.5, 1, 2, 4 and 8 μg/mL) using zebrafish as a model. The results showed that EMB significantly inhibited the hatching rate, spontaneous movement, body length, and swim bladder development of zebrafish embryos, as well as significantly increased the malformation rate of zebrafish larvae. In addition, EMB adversely affected the axon length of motor neurons in Tg (hb9: eGFP) zebrafish and central nervous system (CNS) neurons in Tg (HuC: eGFP) zebrafish and significantly inhibited the locomotor behavior of zebrafish larvae. Meanwhile, EMB induced oxidative damage and was accompanied by increasing reactive oxygen species in the brains of zebrafish larvae. In addition, gene expression involvement in oxidative stress-related (cat, sod and Cu/Zn-sod), GABA neural pathway-related (gat1, gabra1, gad1b, abat and glsa), neurodevelopmental-related (syn2a, gfap, elavl3, shha, gap43 and Nrd) and swim bladder development-related (foxa3, pbxla, mnx1, has2 and elovlla) genes was significantly affected by EMB exposure. In conclusion, our study shows that exposure to EMB during the early life stages of zebrafish significantly increases oxidative damage and inhibits early central neuronal development, motor neuron axon growth and swim bladder development, ultimately leading to neurobehavioral changes in juvenile zebrafish.

Individual persistence under changing climate conditions can be aided by phenotypic plasticity. Needle morphology reflects pine species’ adaptation to their habitats, and adaptive plasticity is beneficial to pine survival. As two closely related pines, Pinusmassoniana Lamb. and Pinus hwangshanensis W. Y. Hsia sympatrically occur in the subtropical region of China, forming hilly forests (i.e., subtropical evergreen needleleaf forests) at lower elevations and montane forests (i.e., temperate evergreen needleleaf forests) at medium and high elevations. However, little is known about the intraspecific phenotypic variation patterns of the two pine species and their relationship with environmental factors. Here, we investigated the interspecific and intraspecific variation patterns of needle traits in the two sympatric pine species, focusing on six traits—i.e., leaf length, leaf thickness, leaf width, leaf area, specific leaf area, and leaf dry matter content—as well as the relationship between needle traits and environmental factors. We found significant phenotypic trait differences among populations of each species. Except for leaf length and leaf width, variation within species was greater than variation between species in the needle traits measured. Even more intriguingly, the leaf size traits (i.e., length, width, thickness) were more conservative than the leaf economic traits (i.e., specific leaf area and leaf dry matter content). In other words, the intraspecific variability of the former was weaker than that of the latter. The nature of P. massoniana needle traits was mainly shaped by latitude, while the needle traits of P. hwangshanensis were significantly affected by annual precipitation. Therefore, phenotypic plasticity may be an essential mechanism for the two pine species to better cope with changing external conditions. The intraspecific variation patterns found in the two pine species and the relationships between traits and environmental factors can provide substantial scientific data for large-scale exploration of intraspecific phenotypic variation in pine species and their breeding practice.