Tree growth and density enhanced, while diversity and spatial clustering reduced soil mycorrhizal C and N sequestration: Strong interaction with soil properties in northeastern China.

In this paper, the effects of species diversity, tree growth, and spatial clustering on mycorrhizal carbon and nitrogen sequestration and the interaction of soil physicochemical properties in Northeast China were investigated. Based on 720 10 m ∗ 10 m plots in Harbin Experimental Forest Farm of Northeast Forestry University, we determined mycorrhizal biomarkers of easily extractable Glomalin-related soil protein (EEG) and total Glomalin-related soil protein (TG). Four plant diversity indices, seven structural metrics, and five soil properties were also measured. We found that: 1) The low tree diversity plots had 1.08-1.23 times higher TG, EEG, TG-N/TN (proportion of N in TG to TN), and TG-C/SOC (proportion of C in TG to SOC) than the high plots. 2) Tree diameter was negatively correlated with EEG and TG, but positively correlated with the EEG and TG contribution to soil TN and SOC. Soil EEG and TG were positively correlated with under-branch height and tree density. W (Uniform Angle Index, higher W indicates more clustering of tree distribution in the plot) was negatively correlated with the above four ratios and positively correlated with EEG/TG. 3) pH was the most powerful explainer for the GRSP variations (6.8 %, strongest negative association with GRSP/TN, R2 > 0.13), followed by soil electrical conductance (6.5 %, positive relation with TG, p < 0.05), AP (3.2 %). 4) Plant diversity mainly affected GRSP traits through the interaction with soils (0.07), tree growth and density directly increased TG, TG-N/TN, and TG-C/SOC, while tree spatial distribution directly reduced TG-N/TN. Our finding highlighted the important effects of tree diversity and forest structural traits on GRSP amount, carbon sequestration, and nutrient retentions, and could support glomalin-related forest soil management of temperate forests in the high-latitude northern hemisphere.

Plant community phylogeny responses to protections and its main drivers in boreal forests, China: General pattern and implications.

Patterns of the phylogenetic structure have been broadly applied to predict community assembly processes. However, the distribution pattern of evolutionary diversity and its drivers under nature conservation are still poorly understood in boreal forests. Here, we investigated 1738 sampling plots and subplots from distinct protection intensities (PIs) zones in five representative National Nature Reserves (NNRs). Multiple comparisons, redundancy analysis, and linear mixed model were performed to identify the changes in community phylogeny across different PIs and NNRs and the drivers for these variations. Our results showed considerable plant community phylogeny variations in different NNRs. As indicated by SesMPD (standardized mean pairwise distance) and SesMNTD (standardized the mean nearest taxon distance), trees, shrubs, and herbs presented overdispersed, clustered, and random distribution patterns, respectively, in different PIs. Protection resulted in the phylogenetic structure between the nearest species of trees showing a more overdispersed pattern (p < 0.05). Protection decreased the phylogenetically clustered degree between the nearest species of shrubs (p > 0.05), while the herbs still maintained a random pattern. Community traits explained the most to phylogeny variation of different communities (24 %-71 %, p < 0.01), followed by geoclimatic factors (2 %-24 %) and conservation processes (1 %-21 %). The higher mean annual precipitation and under branch height at the lower latitude area accompanied the higher SesMPD and SesMNTD. The higher PIs attended with higher tree SesMPD, and the longer protection time resulted in higher shrub PSR (phylogenetic species richness) and PSV (phylogenetic species variability). Including the location of NNRs, community traits, and years of protection, rather than only emphasizing PI itself, could optimize community phylogenetic structure and preserve the evolutionary potential of biodiversity.

Effects of urbanization on woody plant phylogenetic diversity and its associations with landscape features in the high latitude northern hemisphere region, Northeast China.

Urbanization is one of the primary drivers of terrestrial modification, with marked biological homogenization worldwide but relatively poor knowledge of woody phylogenetic diversity. Here, we investigated 943 plots, about 93,000 woody plants from 130 species in Northeast China, and calculated six phylogenetic diversity indexes, and urbanization landscape metrics; the responses of phylogenetic diversity to urbanization and its coupling relationship with landscape features were explored at 25 km × 25 km, 50 km × 50 km and 75 km × 75 km grid scales. We found that urbanization had enhanced the evolutionary distinctiveness of woody plants, characterizing as increasing Faith phylogenetic diversity (FPD) and their mean pairwise distance (MPD) while decreasing the mean nearest taxon distance (MNTD); these trends were independent of landscape scales and gymnosperm inclusion or not. As indicated by increasing SesMPD (Standardized MPD), the dominant role of community assemblage changed from environmental filtering in low urbanization intensity (UI) to competitive exclusion in high UI regions. Artificial surface area (ASA) and its percentage, SHAPE_F (Shape index of forest), and PD_F (Patch density of forest) had a threshold effect on phylogenetic diversity. ASA%, GDP (gross domestic product), and population density were the most potent predictors for the variations of phylogenetic diversity, and GDP contributed the most (42.9%). A higher GDP accompanied a higher FPD, SesPD (Standardized FPD), and SesMNTD (Standardized MNTD); higher PD_F and lower SHAPE_F were associated with higher MNTD, MPD, and SesMPD. In conclusion, urbanization strongly modifies woody plant phylogenetic diversity. Identifying the threshold effects and significant factors for phylogenetic variations allows biodiversity assessment and conservation through proper landscape configuration under the urbanization context.

Relating macrofungal diversity and forest characteristics in boreal forests in China: Conservation effects, inter-forest-type variations, and association decoupling.

QUESTION: How conservation and forest type affect macrofungal compositional diversity is not well understood. Even less is known about macrofungal associations with plants, soils, and geoclimatic conditions. LOCATION: Southern edge of boreal forest distribution in China, named as Huzhong Nature Reserve. METHODS: We surveyed a total of 72 plots for recording macrofungi, plants, and topography in 2015 and measured soil organic carbon, nitrogen, and bulk density. Effects of conservation and forest types on macrofungi and plants were compared, and their associations were decoupled by structural equation modeling (SEM) and redundancy ordination (RDA). RESULTS: Conservation and forest type largely shaped macrofungal diversity. Most of the macrofungal traits declined with the conservation intensities or peaked at the middle conservation region. Similarly, 91% of macrofungal traits declined or peaked in the middle succession stage of birch-larch forests. Forest conservation resulted in the observation of sparse, larch-dominant, larger tree forests. Moreover, the soil outside the Reserve had more water, higher fertility, and lower bulk density, showing miscellaneous wood forest preference. There is a complex association between conservation site characteristics, soils, plants, and macrofungi. Variation partitioning showed that soil N was the top-one factor explaining the macrofungal variations (10%). As shown in SEM coefficients, conservation effect to macrofungi (1.1-1.2, p < .05) was like those from soils (1.2-1.6, p < .05), but much larger than the effect from plants (0.01-0.14, p > .10). For all tested macrofungal traits, 89%-97% of their variations were from soils, and 5%-21% were from conservation measures, while plants compensated 1%-10% of these effects. Our survey found a total of 207 macrofungal species, and 65 of them are new updates in this Reserve, indicating data shortage for the macrofungi list here. CONCLUSION: Our findings provide new data for the joint conservation of macrofungi and plant communities, highlighting the crucial importance of soil matrix for macrofungal conservation in boreal forests.

Solubility, Antioxidation, and Oral Bioavailability Improvement of Mangiferin Microparticles Prepared Using the Supercritical Antisolvent Method.

In view of the poor water solubility and low oral bioavailability of mangiferin (MG), in this study, the supercritical antisolvent (SAS) technology was used to prepare mangiferin microparticles (MG MPs) with N,N-dimethylformamide (DMF) as solvent and carbon dioxide as antisolvent, so as to improve its water solubility, antioxidant capacity and oral bioavailability. Four factors affecting the solubility of the MG MPs were investigated by orthogonal design (OAD), including precipitation pressure, precipitation temperature, MG concentration and feeding speed, and the optimal preparation conditions were determined by range and variance analysis (ANOVA). Under the optimal conditions, the spherical MG MPs with an average diameter of 532.8 nm was obtained, and the yield of the powder was about 95.3%. Scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), X-Ray Diffractometry (XRD), differential scanning calorimetry (DSC), and thermal gravimetric (TG) were used to analyze the characteristics of the MG MPs. The results obtained showed that the chemical structure of the MG did not change before and after supercritical crystallization, but its particle size and crystallinity decreased significantly. The MG MPs had a higher solubility, and was about 4.26, 2.1 and 2.5 times than that of free MG in water, artificial gastric juice (AGJ) and artificial intestinal juice (AIJ), respectively. The dissolution rate of the MG MPs were also obviously higher than that of free MG. Furthermore, the bioavailability of the MG MPs in vivo was about 2.07 times higher than that of the free MG, and its antioxidant capacity was also much higher than that of free MG, which was close to vitamin C.

Differences in quantity and composition of leaf particulate matter and morphological structures in three evergreen trees and their association in Harbin, China.

Urban trees have been assumed to effectively clean air particulate matter (PM), while the inter-species differences are not yet well defined, especially the PM chemical composition. In this study, PM from leaf surface and wax layer of 3 evergreen tree species (Juniper: Juniperus rigida; Black pine: Pinus tabuliformis var. mukdeais; Spruce: Picea koraiensis) were used for finding differences in PM adsorption and its compositional traits (characterized by X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectrum and Inductively coupled plasma-optical emission spectrometry). Possible improvement in PM removal was also evaluated by a detail whole city tree census and different scenarios of species adjustment data. We found that: 1) the amount of PM on juniper leaves was 5.73 g m-2, 2-2.5-fold higher than black pine and spruce (p < 0.05). Of them, 38.73%, 38.22%, and 23.11% were in the wax layer. 2) Compared with the explicit interspecies differences in PM quantity, more complex interspecies difference showed different patterns for different compositional traits. In general, leaf surface PM had higher O, Si, Al, Fe, N, Pb, Cu, Ni, Cr, and Cd, while the wax PM had higher C and Na contents (p < 0.05). 3) Association ordination found that the smaller leaf size, lower leaf water content, higher leaf area per unit mass, higher wax content, and larger stomatal openness aligned with the more PM adsorption by leaf, together with the higher amounts of CO stretching, O, Si, Al, N, heavy metals of Pb, Cu, Ni, Cr, and Cd in PM. 4) Compared with the other 2 species, increase of juniper percentage in urban forests is more effective for maximizing PM removal from air, accompanying more heavy metal removal but less crystalized minerals in PM. Our findings highlight that proper species configuration in urban afforestation could maximize the air PM removal capacity.

Changes in soil properties, X-ray-mineral diffractions and infrared-functional groups in bulk soil and fractions following afforestation of farmland, Northeast China.

Analysis of soil properties, the compositional traits in bulk soil and different fractions and their responses to afforestation practices may possibly facilitate clarification of the mechanisms underlying soil changes. Soil properties, the compositional functional groups and minerals were determined in the bulk soil and fractions from forests and adjacent farmlands. The afforestation of farmland could induce accumulation of soil organic carbon [SOC] (+18%) and nitrogen [N] (+4%) with pH increase (+4%), and declines in electric conductivity (-15%) and bulk density (-3%). Sand and aggregates [SA] and easily oxidized fraction [EO] mainly contributed to the SOC and N accumulation. Moreover, afforestation-induced changes were observed in O-H & N-H stretching (-26%), feldspar (+52%) and huntite crystallinity (-40%). The changes of soil properties were strongly associated with the changes in functional groups, followed by minerals. Of them, asymmetric COO- & C = O stretching & O-H bending, symmetric COO- stretching, huntite and smectite-vermiculite crystallinity were the key factors responsible for the changes of soil properties. Our findings highlight that degraded farmland afforestation could strongly affect soil properties in the bulk soil, and the changes in fractions (mainly SA and EO) as well as their changes in the compositional traits strongly supported these bulk soil changes.

Glomalin contributed more to carbon, nutrients in deeper soils, and differently associated with climates and soil properties in vertical profiles.

Despite vital importance in soil conditioning and a proxy for arbuscular mycorrhizal (AMF), glomalin-related soil protein (GRSP) contribution to soil carbon and nutrients at vertical soil profiles and underlying mechanism were not well-defined yet. Thus, 360 soil samples were collected from 72 farmland 1-m soil profiles in northeastern China, and soil physiochemical properties, nutrients, glomalin characteristics, local climates were determined. Linear decreases of glomalin amounts were observed from the top to deep soils, and glomalin/SOC (glomalin ratio to total SOC) in the 80-100 cm soil (EEG, easily-extracted GRSP, 2.2%; TG, total GRSP, 19%) was 1.34-1.5-fold higher than did in the 0-20 cm soil. Different statistical analyses crosschecked that the lower pH and higher SOC usually accompanied with the higher EEG and TG, while EEG was more sensitive to climates; Moreover, glomalin was more physiochemical-regulated in the deep soils, but more nutrient-regulation was found in the surface soils. Structure Equation Model showed that soil depths and climates indirectly affected TG and EEG features through soil properties, except significant direct effects on EEG. In future, glomalin assessment should fully consider these for identifying the AMF importance in the whole 1-m profile, and our findings also favor degrade soil improvement from glomalin rehabilitation.

Spatial variations in concentration, compositions of glomalin related soil protein in poplar plantations in northeastern China, and possible relations with soil physicochemical properties.

Concentration of Glomalin Related Soil Protein is reportedly close related to soil functions, but few data is available for GRSP compositional variations and function related to soil properties. In this paper, soils from 0-20 cm, 20-40 cm, 40-60 cm, 60-80 cm, and 80-100 cm layers were collected in 72 poplar shelterbelts in Songnen Plain (6 regions) for implementing this data shortage. GRSP mainly consists of stretching of O-H, N-H, C-H, C=O, COO-, C-O, and Si-O-Si and bending of C-H and O-H. It has seven fluorescent substances of tyrosine-like protein, tryptophan-like protein, fulvic acid-like, humic acid-like, soluble microbial byproduct-like, nitrobenzoxadiazole-like, and calcofluor white-like, with characteristic X-ray diffraction peak at 2 θ = 19.8° and 129.3 nm grain size as well as 1.08% low crystallinity. Large spatial variations (intersite and intrasite down profile) were found in either GRSP concentration or these compositional traits. Regression analysis clearly manifested that soil pH should be responsible for these variations. However, negative relations between soil bulk density and GRSP quantity were observed, but not its compositional traits. These basic data in poplar shelterbelt forests are good for understanding the underlying mechanism of GRSP in soil functional maintenance.