Huijing Ni's research while affiliated with International Center for Bamboo and Rattan and other places

Lei bamboo ( Phyllostachys violascensʻPrevernalisʼ ) is a high economic value species with high yield and good quality of bamboo shoots. However, heavy chemical fertilizer and covering cultivation are used to produce off-season bamboo shoots, resulting in soil degradation and a decline in soil productivity. This study introduced an amino acid fertilizer called fish protein fertilizer to replace part of chemical fertilizer, and investigated the effect of different fertilizer combinations on bamboo growth, shoot yield and soil properties to clarify the growth-promoting mechanism of amino acid fertilizer. Results showed that after replacing 45 kg of compound fertilizer with 10 kg or 20 kg of fish protein fertilizer (1) bamboo shoot yield increased by 23.24% or 26.19%, respectively; (2) growth of leaves and roots were enhanced, thick root proportion increased, and proportion of root in the topsoil layer decreased; (3) soil pH, contents of AP (available phosphate), SOC (soil organic carbon), MBC (microbial biomass carbon) and MBN (microbial biomass nitrogen), soil enzyme activity increased; (4) contents of N and P in leaf increased, while the N/P and K/P decreased. Overall, amino acid fertilizer can promote microbial growth and improve soil enzyme activity through supplying carbon sources and nitrogen sources, thus promoting phosphorus activation and increasing soil phosphorus effectiveness, and then improving the foraging scale of root systems, and ultimately enhancing nutrients absorption and increasing bamboo shoot yield.

Lei bamboo (Phyllostachys praecox) is an economically viable bamboo species with rich nutrition, a good taste, and a high yield. However, heavy fertilization and covering cultivation are used to produce off-season bamboo shoots, resulting in soil degradation and a decline in site productivity. This study investigated how compound fertilizer decrement and water-soluble humic acid fertilizer application affects soil properties and shoot yield in Lei bamboo plantations of subtropical China. The soil nutrients, enzyme activities, and shoot yield were examined, the bacterial community structure was determined using the high-throughput sequencing method, and their relationships were evaluated under different fertilization treatments: single compound fertilizer and compound fertilizer decrement with water-soluble humic acid fertilizer applications. Compared with those after single compound fertilizer treatments (CF1, CF2), water-soluble humic acid fertilizer addition (CF2HA1, CF2HA2) increased soil organic carbon (SOC), available phosphorus (AP), microbial biomass nitrogen (MBN) contents, the ratio of SOC to total nitrogen (C/N), and sucrase and acid phosphatase (Acp) activities, and decreased alkali hydrolyzed nitrogen (AN) and microbial biomass carbon (MBC) contents. The bacterial community phyla comprised 83.62%–86.16% Proteobacteria, Acidobacteria, Bacteroidetes, Actinobacteria, and Chloroflexi. Water-soluble humic acid fertilizer application also significantly increased yields by over 30%. AP and MBN were important drivers affecting soil bacterial communities, whereas SOC, MBN, and Chloroflexi affected Lei bamboo shoots. Overall, compound fertilizer decrement and water-soluble humic acid fertilizer application shifted the available soil nutrients, sucrase and Acp activity, bacterial community diversity, and shoot yield. An improved understanding of humic acid and the application of humic acid water-soluble fertilizer are of great significance for soil improvement, ecological restoration, and the sustainable management of bamboo forests in the future.

Aims To demonstrate how intensive management practices affect the belowground productivity of Moso bamboo, we examined the spatial distribution of fine root traits under three stands with high-intensity (T1, tillage plus biennial fertilization), low-intensity (T2, tillage plus quadrennial fertilization), and extensive (CK, no-tillage plus no fertilization) management, and evaluated the relationships among root traits and soil properties, aggregate stability (MWD). Methods Bamboo fine root and soil samples were collected from three depths (0–10, 10–20, 20–30 cm) and three horizontal distances (20, 40, 60 cm) under three management strategies. Root biomass, root morphology, soil properties, and aggregate composition were determined. Results Compared with CK, T1 and T2 had higher fine root biomass (FRB), and the largest FRB in the 10–20 cm soil layer. T1 had significantly higher allocation proportion of D1–2 class FRB and root length density (RLD) and significantly lower specific root length (SRL) and specific surface area (SSA). Vertically, intensive management led to an increase in FRB in the 10–20-cm soil layer and MWD in the 20–30-cm soil layer. Horizontally, FRB was highest at a distance of 20 cm from bamboo culm. A strong positive correlation was identified among FRB, RLD, and TP in each soil layer as well as among MWD, TP, and RLD. Conclusions Intensive management promotes fine root growth with high length in response to more soil P content, and high-intensity management shifts the expression of root functional traits toward transport fine roots proportion and 10–20-cm soil layer, and facilitates aboveground productivity of Moso bamboo. TOC, TP, and RLD are the main three drivers correlated with soil aggregate stability.

The application of nitrogen fertilizer is crucial in the cultivation of bamboo forests, and comprehending the alterations in soil organic carbon (SOC) due to nitrogen application is essential for monitoring soil quality. Predicting the dynamics of soil carbon stock involves analyzing two components: particulate organic carbon (POC) and mineral-associated organic carbon (MAOC). This study aimed to investigate the impact of high nitrogen inputs on SOC stock in Moso bamboo forests located in southwestern China. The research focused on analyzing changes in soil chemical properties, SOC content, and its components (POC and MAOC), as well as microbial biomass in the surface layer (0–10 cm) under different nitrogen applications (0, 242, 484, and 726 kg N ha−1 yr−1). The results indicate that nitrogen application significantly reduced the SOC content, while concurrently causing a significant increase in POC content and a decrease in MAOC content within the Moso bamboo forest (p < 0.05). The HM treatment notably increased the NO3−-N content to 2.15 mg/kg and decreased the NH4+-N content to 11.29 mg/kg, although it did not significantly influence the microbial biomass carbon (MBC) and nitrogen (MBN). The LN and MN treatments significantly reduced the MBC and MBN contents (71.6% and 70.8%, 62.5% and 56.8%). Nitrogen application significantly increased the Na+ concentration, with a peak observed under the LN treatment (135.94 mg/kg, p < 0.05). The MN treatment significantly increased the concentrations of Fe3+ and Al3+ (p < 0.05), whereas nitrogen application did not significantly affect Ca2+, Mg2+ concentration, and cation exchange capacity (p > 0.05). Correlation and redundancy analyses (RDAs) revealed that the increase in annual litterfall did not significantly correlate with the rise in POC, and changes in extractable cations were not significantly correlated with the decrease in MAOC. Soil nitrogen availability, MBC, and MBN were identified as the primary factors affecting POC and MAOC content. In conclusion, the application of nitrogen has a detrimental impact on the soil organic carbon (SOC) of Moso bamboo forests. Consequently, it is imperative to regulate fertilization levels in order to preserve soil quality when managing these forests. Our research offers a theoretical foundation for comprehending and forecasting alterations in soil carbon stocks within bamboo forest ecosystems, thereby bolstering the sustainable management of Moso bamboo forests.

The drought tolerance of plants is significantly influenced by their root architecture traits and root adaptive strategies, but the key root architecture traits that affect drought tolerance and the differences in drought adaptative strategies of species with varying root architectures are not yet clear. This study aimed to investigate the response of three species’ roots to drought and evaluate the key root architecture traits affecting the drought tolerance of the three species. One-year-old potted seedlings of three species [Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.), masson pine (Pinus massoniana (Lamb.)), and moso bamboo (Phyllostachys edulis (Carr.) H. de Lehaie f. edulis)] were planted in a greenhouse under three drought conditions (sufficient water supply, moderate drought, and severe drought) for 90 days. Biomass, root morphology [root surface area (RSA), root length (RL), root diameter (RD)], root architecture [root topological index (TI), fractal dimension (FD), and root branching angle (RBA)] of seedlings were measured monthly. The drought tolerance of species was quantified by studying the response ratio (RR) of root length and biomass in response to drought. We found that: (i) different levels of drought inhibited the biomass accumulation and root growth of the three species, and drought tolerance showed a decreasing order as pine > Chinese fir > bamboo; (ii) drought decreased the RD in bamboo but increased it in pine. Both bamboo and Chinese fir reduced their FD and RBA under drought stress, while pine was relatively stable. All the three species’ roots tended to develop a herringbone branching architecture (increase their TI) under drought stress; (iii) both TI and FD were negatively correlated with the drought tolerance of the seedlings. Our results indicated that plants could adapt to drought by different strategies such as adjusting biomass allocation and root morphology, reducing root branch strength, and branching angles. Roots with narrower branching angles, greater branching complexity, larger TI, and consuming higher cost are more drought-tolerant.

Understanding rhizosphere processes in relation to the aboveground productivity of bamboo stands may shed new light on the optimization of management practices and the ecological functions of belowground components in forest ecosystems. In this paper, Moso bamboo stands under intensive management with high-intensity (deep plowing plus biennial fertilization, T1) and low-intensity (deep plowing plus quadrennial fertilization, T2) practices were compared with those managed conventionally (no-tillage plus no fertilization, CK) to evaluate the impacts of intensive management strategies on the content and forms of soil C, N, and P, their associated microbial biomasses, abundances, and enzyme activities, and their relationships with bamboo root growth, nutrient uptake, and aboveground biomass. Bulk and rhizosphere soil samples from four adjacent extensively–intensively managed Moso bamboo plantation pairs were collected from a subtropical region in Zhejiang Province, China. The results show that compared with CK, intensive management practices, including T1 and T2, significantly decrease the total organic C, labile soil organic C pools including readily oxidizable C, free particulate organic C, and hot-water-extractable organic C, total N, water-soluble organic N, NH4⁺-N, NO3⁻-N, total P, organic P, and inorganic P content in the rhizosphere, but increase the content of water-soluble organic N, NH4⁺-N, and NO3⁻-N, as well as organic P and inorganic P, in the bulk soil surrounding the plant roots. Furthermore, microbial biomass C, microbial biomass N, bacterial and fungal abundances, and enzymes activities (urease, peroxidase, catalase, polyphenol oxidase, and β-glucosidase) involved in C and N metabolism were significantly decreased in the rhizosphere while acid phosphatase activity was enhanced. These changes were inferred from changes in the active C, N, and inorganic P fractions. Contrastingly, root growth traits, including biomass, length, diameter, and volume, increased continuously in response to the greater soil nutrient heterogeneity in the root zone caused by intensive management, thereby promoting root N, P, and K uptake and increasing the aboveground biomass. In conclusion, intensive management practices significantly promoted root development, growth, and biomass production in bamboo stands, but had notable negative effects on rhizosphere nutrient pools and biological properties, with potential impacts on soil functioning including in soil C sequestration and nutrient cycling.

Moso bamboo (Phyllostachys edulis) is widely considered to be effective in capturing and sequestering atmospheric C, but the long-term effects of extensive management strategies on soil organic carbon (SOC), bacterial communities, fine root (FR, ø ≤ 2 mm) traits, and their inherent connection remain unclear. In this study, we simultaneously measured the SOC content of the bulk and rhizosphere soil fractions, the aggregate stability, the chemical composition of SOC (solid-state ¹³C nuclear magnetic resonance [NMR]), the bacterial community structure in the rhizosphere, and the FR morphological traits including biomass, specific root length (SRL), and root length density (RLD) along a chronosequence (stand age of 19, 37, and 64 years) of extensively managed Moso bamboo plantations and in an adjacent secondary forest as a control. The organic C content in both the rhizosphere and bulk soil increased rapidly with plantation age in the 0–20- and 20–40-cm soil layers, accompanied by an increase in the aggregate stability. FR traits including biomass, SRL, and RLD also increased continuously in response to soil C:N:P stoichiometry. All of these traits were significantly correlated with SOC, occluded particulate organic C (oPOC), and mineral-associated organic C (MOC), suggesting that FR traits could drive the soil C sequestration with the plantation age. Further analysis indicated that the microbial biomass C (MBC) content, MBC/total organic carbon (TOC) ratio, and bacterial abundance decreased with the plantation age, and the shift from soil oligotrophy to copiotrophy bacteria were mainly driven by changes in FR traits and SOC properties. Such a reassembly of bacterial communities combined with an increase in root biomass is favorable for the accumulation of stable C functional groups (alkyl C or aromatic C). Our findings indicate that extensive management regimes of Moso bamboo plantations could promote long-term soil C sequestration especially in the rhizosphere by promoting the formation of soil aggregates and organic-mineral complexes and by shifting bacterial community composition, and that these changes can be inferred through changes in the FR traits.

Moso bamboo (Phyllostachys edulis) is widely distributed in southern China, and is one of the fastest growing plants worldwide; however, information remains limited on the impact of converting secondary broad-leaved evergreen forests to Moso bamboo plantations, and how the soil organic carbon (SOC) pool and its chemical composition should be managed subsequently. To elucidate these effects, three representative areas were chosen, all with very similar site conditions. In each area, four comparable stands were selected; namely, undisturbed (M0), extensively managed (M1), and intensively managed (M2) stands in each Moso bamboo plantation, and a secondary broad-leaved evergreen forest (CK). Soil samples were collected and examined from depths of 0–20 and 20–40 cm in all 12 stands. The results showed that, SOC and mineral-associated organic matter C (MOM-C) stocks in 0–40 cm soil depths were significantly higher in M0 and M1 than in CK; however, these two parameters were significantly lower in M2. M0 and M1 showed a significant decline in the ratio of microbial biomass C (MBC) to total organic C (TOC), hot-water-extractable organic C (DOC) to TOC, and the C mineralization rate. However, M2 showed a significant increase compared to CK for all of these parameters. Fourier-transform infrared spectroscopy (FTIR) showed that land-use conversion also changed SOC chemical composition. Compared with CK and M2, M0 and M1 showed lower relative content of polysaccharides and higher content of recalcitrant compounds and soil hydrophobicity. Aliphatic and aromatic compounds were positively correlated with accumulated C sequestration in all fractions but negatively correlated with microbial activity in both soil layers; thus, chemical protection mechanism was important for stabilizing the soil in M0 and M1. Overall, Moso bamboo plantations with management strategies M0 and M1 could stabilize more C through promoting the formation of stable organic-mineral complexes and the accumulation of resistant organic components, showing much higher potential in terms of soil C sequestration than M2.