应用生态学报最新文献

We isolated the dark septate endophytic (DSE) fungi from roots of typical plant species in the tundra of Changbai Mountains Nature Reserve, including Rhododendron aureum, R. conferentiatum, Vaccinium uliginosum, and Dryas octopetala, and studied their colonization. We further investigated the DSE community composition and species diversity of the four tundra plant species by using morphological characteristics combined with rDNA ITS sequence analysis. The results showed that DSE formed a typical structure of "microsclerotia" in roots of the four plant species. A total of 69 strains of DSE fungi were isolated from the root samples, belonging to 10 genera, and 12 species. They were Phialocephala fortinii, Alternaria alternata, A. tenuissima, Epicocum nigrum, Canariomyces microsporus, Colletotrichum spaethianum, C. camelliae, Leptophoria sp., Cladosporium cladosporioides, Phoma sp., Cadophora sp., and Discosia italica, respectively. The DSE fungal species diversity was rich, and all these fungal species were firstly reported as DSE fungi in the alpine tundra belt of China. Among them, Phialocephala fortinii was the common and dominant species of all tundra plants. The Simpson, Pielou, and Shannon diversity indices of DSE fungi of the four plant species of tundra differed significantly. Our results showed that tundra plants have rich diversity of DSE fungi, and they can form a good symbiotic relationship, which enhance the adaptability of tundra plants to the harsh environment.

Effective microorganisms (EM) might alleviate deterioration of soil environmental quality and yield decline of pepper (Capsicum annuum) caused by continuous replanting and imbalanced fertilizer application in Xinjiang. We investigated the effects of applying EM microbial agent on the growth of pepper plants, yield, soil nutrient content, soil enzyme activity, and rhizosphere eukaryotic community. The results showed that the application of EM microbial agent increased plant height, stem diameter, leaf length, leaf width and root length by 22.6%, 35.3%, 33.3%, 29.7% and 15.1%, respectively. It also increased fruit width, individual fruit weight, and yield by 5.3%, 42.9%, and 74.7%, respectively. After the application of EM microbial agent, the levels of soil available nitrogen increased by 10.2% and 5.8% during the flowering and maturity stages, respectively. Similarly, available phosphorus increased by 10.4% and 13.4%, respectively. The soil sucrase activity was increased by 40.7%, 14.6%, and 9.3% during the seedling, flowering, and maturity stages, respectively. Urease activity was also increased by 7.9%, 10.2%, and 11.5%, respectively. Furthermore, the application of EM microbial agent increased soil peroxidase activity by 16.8% and 44.6% at flowering and maturity stages, respectively. The application of microbial agent significantly altered the β-diversity of the rhizosphere eukaryotic community in pepper plants. Specifically, microbial agent increased the relative abundances of populations belonging to Enchytraeus and Sminthurides genera, which could contribute to soil improvement and nutrient cycling. Compared to the CK, the relative abundance of pathogenic microorganisms including Olpidium and Aplanochytrium genera decreased by 98.0% and 89.3%, and the relative abundance of the Verticillium decreased to 0. These results demonstrated that EM microbial agent could increase soil nutrient content, enhance soil enzyme activity, and reduce soil pathogenic fungi in the pepper cultivation areas of Xinjiang, thus achieving beneficial effects on pepper growth and fruit yield.

Improving the availability of soil phosphorus (P) and promoting tree growth through tree species selection and assembly are the critical issue. We conducted an afforestation experiment following randomized block experimental design with 1, 2, 4, and 6 tree species richness in south subtropics, including Pinus massoniana, Mytilaria laosensis, Erythrophleum fordii, Castanopsis hystrix, Michelia macclurei, Manglietia glauca, Aquilaria sinensis, and Dalbergia odorifera. We measured the bioavailable P components (CaCl₂-P, citrate-P, enzyme-P and HCl-P) and examined the effects of different tree species assembly on bioavailable P components and tree growth. The results showed that, compared with non-nitrogen-fixing tree species, the mixing of nitrogen-fixing tree species (E. fordii and D. odorifera) effectively increased the contents of soil water, total nitrogen, total phosphorus, and microbial biomass P (MBP). The assembly of specific tree species improved the accumulation of bioavailable P. Mixing of nitrogen-fixing tree species significantly increased CaCl₂-P content by 46.2% to 160.3%, the enzyme-P content produced by microbial mineralization by 69.3% to 688.2%, and HCl-P by 31.5% to 81.3%, increased MBP by 81.8% to 149.4%, and microbial biomass N (MBN) by 88.1% to 160.6%, respectively. Redundancy and correlation analysis results showed that MBP, available P, total phosphorus, L-leucine aminopeptidase, cellobiose, acid phosphatase, MBN and soil organic carbon were key factors driving the variation of rhizosphere soil bioavailable P. Mixing of nitrogen-fixing tree species increased enzyme-P and citrate-P, and the availability of which were positively correlated to tree basal area. In this study, mixing of nitrogen-fixing tree species increased the rhizosphere soil bioavailable P content, which facilitates tree growth.

We studied the population characteristics of Caragana microphylla and related soil factors across diffe-rent stages of shrub encroachment (i.e., light, moderate, and severe) on the Xilingol Grassland of Inner Mongolia. The results showed that the density and height of C. microphylla gradually increased during the process of grassland shrub-encroachment from light to moderate to severe. The density and height were increased by 196.0% and 34.5% from light to moderate stage of shrub encroachment, and were increased by 25.4% and 17.6% from moderate to severe stage. Crown size, basal diameter, tiller number per clump, and aboveground productivity of C. microphylla tented to decrease first and then increase, while the proportion of aboveground biomass allocation to leaves decreased across the stages of shrub encroachment. The competition between C. microphylla and herbaceous species was strongest in the moderate encroachment stage. C. microphylla reduced its lateral growth (such as crown size, basal diameter, and tiller number per clump) and increased density and height to get competitive advantage. Limi-ting soil factors for C. microphylla varied significantly at different stages of shrub encroachment. In the light encroachment stage, soil factors had little effect on the growth of C. microphylla. In the moderate encroachment stage, soil moisture in the deep layer (20-50 cm) and soil pH were the key factors limiting shrub density. In the severe encroachment stage, soil moisture in the deep layer and pH limited the vertical growth of C. microphylla, while soil moisture of shallow layer (0-20 cm) and nutrients were the limiting factors for the lateral expansion of shrubs.

Low temperature (LT) in spring usually occurs at the booting of winter wheat, resulting in reduction of wheat yield. In this study, we used the LT-sensitive wheat cultivar 'Wanmai 52' and the LT-insensitive wheat cultivar 'Yannong 19' as experimental materials to conduct LT treatment (-2 ℃ and 0 ℃) at booting stage. After the LT treatment, we sprayed 6-benzylaminoadenine (6-BA) solutions with concentrations of 10, 20, and 30 mg·L^-1 respectively, with equal mass distilled water as control to investigate the effects of spraying 6-BA on the physiological characteristics, yield and quality of wheat flag leaves after LT stress at booting stage. The results showed that compared with the control, young ear of wheat treated with exogenous spraying 6-BA was fuller, the floret morphology was improved, and the number of vascular bundles under the spike was increased. 6-BA application promoted the accumulation of soluble sugar, soluble protein, and proline in flag leaves. The activities of peroxidase and superoxide dismutase were increased, and the content of malondialdehyde was decreased. Exogenous 6-BA application decreased the number of degenerated spikes of wheat, increased the number of grains per spike and 1000-grain weight, as well as the contents of grain protein, wet gluten, and sedimentation value. In summary, exogenous 6-BA application could effectively alleviate the effects of LT stress on flag leaf and yield of wheat. Under the conditions of this experiment, the mitigation effect of spraying 6-BA solution on Yannong 19 was higher than that of Wanmai 52, and the mitigation effect of spraying 20 mg·L^-1 6-BA solution on low temperature stress was the best.

Understanding the composition and spatial distribution patterns of microbial communities in plateau peatland soils is crucial for preserving the structural and functional stability of highland wetlands. We collected 50 soil samples from the core conservation area of Zoige peatland along horizontal and vertical distributions to analyze the soil bacterial and fungal diversity by using high-throughput sequencing technology, combined with Mantel tests and multiple regression on matrices (MRM) statistical methods, as well as the spatial distribution characteristics of community structure similarity at a local scale. The results showed that the dominant soil bacterial and fungal groups were Chloroflexi (accounting for 33.2% and 25.1% of the total bacterial community in horizontal and vertical directions, respectively) and Ascomycota (54.7% and 76.4%). The similarity of microbial community structure in both horizontal and vertical directions decreased with increasing spatial distance of the sampling points. The turnover rates of bacterial and fungal communities in the vertical direction were 8.8 and 8.6 times as those in the horizontal direction, respectively. Based on the relative abundance of the communities, we classified microbes into six groups. As the number of rare species in the community increased, the slope of community distance decay decreased. The conditionally rare or abundant taxa (CRAT) category group showed the most similar spatial distribution characteristics to the total microbial community. Mantel analysis indicated that soil organic carbon, total nitrogen, and available phosphorus were key factors driving the distribution of bacterial and fungal communities in the horizontal direction, while soil organic carbon, available carbon, pH, and soil bulk density were the main factors determining the vertical distribution. MRM analysis further showed that both soil physicochemical indicators and spatial distance significantly affected the assembly of microbial communities, where soil factors explained more about the vertical distribution of microbial communities than the horizontal distribution. The impact of soil factors on microbial community distribution was much greater than that of spatial factors through diffusion limitation. In summary, the microbial communities in the plateau peatland soils exhibited more pronounced vertical distribution differences and environmental response characteristics.

Exploring the temporal and spatial dynamics of vegetation coverage in the Heilongjiang Basin and its response to climate change can provide a theoretical basis and data support for integrated basin management for three countries (Mongolia, China and Russia) in the region. We used MOD13Q1 remote sensing data from Google Earth Engine (GEE) platform between 2000 and 2020 to process the normalized vegetation index (NDVI) through the maximum value composites method, and calculated the vegetation coverage (FVC) using the dimidiate pixel model. The Sen+MK trend analysis method was employed to monitor the dynamics of FVC, while the Pearson correlation coefficient was utilized to quantify the responses of FVC to climate change. The results showed that the overall FVC in the Heilongjiang Basin exhibited a slight decreasing trend during 2000-2020, with an annual rate of 0.1%. The FVC in Mongolia showed a fluctuating increase trend (0.13%), while slight decrease trends were observed for Russia (0.15%) and China (0.08%). The FVC predominantly slightly degraded and severely degraded, accounting for 34% and 17% of the area, respectively, while the significantly improved area only accounted for 9%. The impact of precipitation on FVC in the study area was significantly greater than that of temperature. The proportion of areas where precipitation and temperature had a significant impact on FVC was 8.2% and 2.2%, respectively. The correlation coefficient between precipitation and FVC was the highest in Mongolia (r=0.446, P<0.05), and the lowest in Russian region (r=-0.442, P< 0.05).

The contribution of litterfall nutrient return to the maintenance of soil carbon pool and nutrient cycling is a crucial aspect of forest ecosystem functioning. Taking 21 tree species in subtropical young plantations as subjects, we investigated the correlation between litterfall nutrient return characteristics and functional traits of leaf and root and. The results showed notable variations in litterfall production, standing crop, and nutrient return across all the examined tree species. Mytilaria laosensis exhibited the highest litterfall production (689.2 g·m^-2·a^-1) and standing crop (605.1 g·m^-2), while Cryptomeria fortunei demonstrated the lowest litterfall production (36.0 g·m^-2·a^-1) and standing crop (10.0 g·m^-2). The nitrogen and phosphorus return amounts of 21 species ranged from 3.0 to 48.3 kg·hm^-2 and from 0.1 to 2.0 kg·hm^-2, respectively. Castanopsis fissa demonstrated the highest nitrogen return, while Liquidambar formosana exhibited the highest phosphorus return. C. fortunei had the lowest nitrogen and phosphorus return. Results of the stepwise regression analysis indicated that litterfall production exhibited a significant negative correlation with leaf nitrogen content and leaf dry matter content, and a significant positive correlation with fine root tissue density. Additionally, leaf nitrogen content, leaf dry matter content, and specific root length had a significant negative impact on standing crop. The structural equation modelling results indicated that leaf dry matter content had a direct or indirect negative effect on nitrogen return amount through the reduction of litterfall production. Conversely, fine root tissue density had a significant positive impact on nitrogen return amount by increasing litter leaf nitrogen content. Both leaf nitrogen content and leaf dry matter content had direct or indirect negative effects on phosphorus return amount through the reduction of litterfall production. In conclusion, the tree species with low leaf nitrogen content and dry matter content, as well as high fine root tissue density, was recommended for the establishment of plantations in the subtropical zone in order to enhance nutrient cycling through litter decomposition and improve soil fertility and forest productivity.

Rhizosphere is a vital area for substance exchange and energy transfer between roots and soil microorganisms. Therefore, diazotrophs in the rhizosphere play a pivotal role in facilitating plant nitrogen acquisition. We investigated the variability in the abundance and community structure of soil diazotrophs and the influencing factors across rhizosphere soils of Cunninghamia lanceolata in three locations: Baisha State-owned Forest Farm in Longyan City (BS), Sanming Forest Ecosystem and Global Change Research Station (SM), and Wuyishan National Forest Park in Nanping City (WYS), located in the western region of Fujian Province, quantified the diazotrophic abundance by using real-time quantitative PCR, and assessed the community structure by high-throughput sequencing. The results showed that soil pH, C:N ratio, and C:(N:P) stoichiometry in SM were notably lower compared to those in BS and WYS. In SM, the abundance of the nifH gene was 6.38×10⁸ copies·g^-1, significantly lower than 1.35×10⁹ copies·g^-1 in BS and 1.10×10⁹ copies·g^-1 in WYS. Additionally, α diversity index of diazotrophs was lower in SM compared to BS and WYS, while the community structure of diazotrophs in rhizosphere soils of BS and WYS was similar, which differed significantly from that in SM. The diazotrophic sequences in the three forest farms could be divided into 5 phylum, 8 classes, 15 orders, 23 families and 33 genera, with Proteobacteria, α-proteobacteria, and Bradyrhizobium as the dominant phylotypes. Soil pH, available phosphorus, NO₃^--N and C:(N:P) ratio were identified as significant factors influencing both the abundance and community structure of nifH genes, with soil pH performing the greatest. Taken together, there were spatial variations in the distribution of diazotrophic abundance and community structure in C. lanceolata rhizosphere soils, with soil pH as the primary driving factor.

We analyzed age structure and dynamics, spatial distribution patterns, and reproductive capabilities of four Rosa persica populations in Xinjiang, to evaluate the survival status of the species and explore the reasons behind its endangerment. The results showed that the populations had fewer individuals in the youngest (Ⅰ) and oldest (Ⅵ-Ⅷ) age classes, with a predominance of middle-aged individuals, resulting in an irregular pyramid-shaped distribution, described as "high in the middle, low on both sides". The populations were generally growing, but were susceptible to external environmental disturbances (V_pi'＞0, P_max＞0). The mortality rate (q_x) and vanish rate (K_x) peaked at age Ⅴ, leading to a sharp decline in plant abundance. The life expectancy (e_x) decreased progressively with the increases of age class, reaching its lowest at age Ⅷ, which indicated minimal vitality at this stage. A time sequence analysis predicted a future dominance of individuals at age Ⅴ-Ⅷ, suggesting an aging trend. Spatially, the four populations were predominantly clumped, with the intensity of clumping ranked from highest to lowest as P₄, P₃, P₁, and P₂. P₃ and P₄ exhibited better reproductive capabilities than P₁ and P₂. There was a significant positive correlation between hundred-fruit weight and plant height and crown width, and between total seed number and crown width and hundred-fruit weight.