应用生态学报最新文献

We analyzed the differences in knot property of linear and curved knots of dominant, medium, and inferior wood with thirty-three Pinus koraiensis trees from Mengjiagang Forest Farm and Linkou Forestry Bureau in Heilongjiang Province. We divided the 33 trees into two groups according to the height of the site index. We constructed a trunk diameter growth models to explore the connection, between the knot growth inflection points and the successive growth of diameter, and to screen for the types that had a weaker impact on wood quality. The results showed that there were significant differences in knot diameter, sound knot length, proportion of loose knot and inflection point age between the two knot types. The growth inflection point of curved knot was between 8 and 12 years old, while that of linear knot was between 7 and 10 years old. The knot of curved knots in different grades of wood were larger than linear knot in terms of knot diameter and sound knot length. The decrease in the proportion of sparse knots indicated that the healing time of knot became shorter. The growth of linear knots remained essentially uniform with radial growth. The age of the growth inflection point of curved knots was later than the age at which the maximum of successive annual growth in diameter was produced. The age of trunk diameter inflection and the age of knot growth inflection were later for better site conditions. The age of trunk diameter inflection and the age of knot growth inflection were later for dominant woods than for average nodule growth. Different site conditions and trunk diameters affected nodule growth, and nodule attributes differed between the two nodule types as trunk diameter grew. Delaying the maximum continuous annual growth by rationally formulating forest management measures can lengthen the duration of trunk growth while extending branch growth, increase the proportion of curved knot to optimize wood quality, and improve wood quality.

Hippophae rhamnoides subsp. sinensis is an important resource plant with considerable medicinal, economic, and ecological value, and an indicator species in the transition zones between forests and grasslands. Predicting the potential geographic distribution of H. rhamnoides subsp. sinensis under climate change can reveal the responses of China's grassland and forest to global climate change, which is of significance for the conservation and development of its resources. We utilized distribution data of H. rhamnoides subsp. sinensis to predict its suitable habitats under future climate change based on the Biomod2 ensemble model, and analyzed the trend of land use type change in these habitats in conjunction with remote sensing data of land use types in China in 2020. The results showed that the Biomod2 ensemble model significantly improved the accuracy and precision of predicting H. rhamnoides subsp. sinensis compared to single models. The distribution of H. rhamnoides subsp. sinensis was primarily concentrated on both sides of the diagonal from Liaoning to Tibet, situated in forest-grassland ecotone. Under the SSP126 scenario, the suitable habitats for H. rhamnoides subsp. sinensis would initially expand and then contract. Under the SSP585 scenario, they would show a continuous expansion trend. In the context of global warming, the suitable habitats for H. rhamnoides subsp. sinensis would expand. By 2050 and 2070, the area of suitable habitats for H. rhamnoides subsp. sinensis in grasslands would increase, while areas currently occupied by forests, croplands, and developed land would continue to decrease. Under future climate change, the distribution center of H. rhamnoides subsp. sinensis would migrate towards higher-altitude grassland areas. Among the environmental factors affecting the distribution of H. rhamnoides subsp. sinensis, climate variables were predominant, with the highest contribution of rainfall during the warmest season.

To clarify the response mechanism of exogenous paclobutrazol on drought resistance in Phoebe bournei seedlings, we investigated the effects of spraying different concentrations of paclobutrazol (25, 50, 100 mg·L^-1) on the photosynthetic and antioxidant systems of 2-year-old P. bournei seedlings under drought stress using natural drought method. The results showed that drought stress significantly reduced the photosynthesis and broke the dynamic balance of antioxidant system in P. bournei seedlings. Spraying with different concentrations of paclobutrazol effectively alleviated the negative impacts of drought stress, and enhanced the defense capability of photosynthetic and antioxidant systems, with the 100 mg·L^-1 paclobutrazol treatment being the most effective. Under exogenous 100 mg·L^-1 paclobutrazol treatment, the total chlorophyll in leaves increased significantly, with a maximum increase of 51.9%. The apparent photosynthetic electron transfer rate, photochemical quenching coefficient and actual photochemical quantum yield were significantly increased, with maximum increase of 67.8%, 58.4%, and 59.7%, respectively. The net photosynthetic rate, stomatal conductance and transpiration rate, were enhanced, reaching maximum increase of 65.5%, 65.4%, and 68.6%, respectively. In summary, exogenous 100 mg·L^-1paclobutrazol has the strongest ability to enhance drought resistance of P. bournei seedlings by regulating photosynthetic and antioxidant systems.

Petroleum hydrocarbon pollutants in soil are challenging to biodegrade, negatively impacting plant growth as well as the metabolic activity and community structure of soil microorganisms. Microorganisms immobilized by seed carriers can synergistically contribute to the remediation of petroleum hydrocarbon-contaminated soil. We prepared a rape seed carrier with immobilized microorganism by seed coating (with a mixture of diatomaceous earth and bentonite as fillers) and microbial immobilization. A pot experiment was conducted with the following treatments: control (CK, neither seeds nor microorganisms added), bare rapeseed (T₁), rapeseed coated with diatomaceous earth and bentonite (T₂), free-living Pseudomonas aeruginosa added (T₃), rapeseed coated with diatomaceous earth and bentonite plus free-living P. aeruginosa (T₄), and rapeseed coated with diatomaceous earth and bentonite immobilized with P. aeruginosa (T₅). We measured rape seed growth, rhizosphere microbial community structure, and petroleum hydrocarbon removal efficiency. The results showed that 1) There were no significant difference in seed germination rate among T₁, T₂, T₄, and T₅ treatments. Compared to T₁, leaf length, root length, biomass, and soluble protein content of rape seed significantly increased in T₄ and T₅ treatments, while T₂ treatment showed no significant effect. Leaf width, stem length, chlorophyll content, and superoxide dismutase activity of rape seed in T₂, T₄, and T₅ treatments were significantly higher than T₁, while malondialdehyde content was signi-ficantly lower. 2) Compared to CK, the removal rate of petroleum hydrocarbon in the T₁, T₂, T₃, T₄, and T₅ treatments increased by 0.8, 1.6, 0.5, 1.8, and 2.2 times, respectively. The T₅ treatment achieved the highest petro-leum hydrocarbon removal rate of 54.0%. Soil dehydrogenase activity in all treatments increased significantly, with a positive correlation with the petroleum hydrocarbon removal rate (r=0.893). 3) The T₅ treatment had the highest soil microbial α diversity and the abundances of Chloroflexi and Acidobacteria. In conclusion, seed carriers with immobilized microorganisms could regulate plant growth, modify the structures of microbial communities, enhance the biological activity of soil enzymes, thereby improving petroleum hydrocarbon removal efficiency. This provides a novel environmentally friendly approach for the joint remediation of petroleum hydrocarbon-polluted soil by plants and microorganisms.

To understand the distribution pattern and influencing factors of plant community and diversity along the altitude gradient, we examined plant community types, plant diversity and phylogenetic diversity of mountain steppe in Luoshan, Ningxia, and analyzed the relationship between the plant community and its diversity and environmental driving factors. The results showed that the main community types in the mountain steppe were Asterothamnus centraliasiaticus community, Caragana tibetica community, Convolvulus tragacanthoides community, Stipa bungeana community, Stipa breviflora＋Ajania achilloides community, Artemisia frigida community, Roegneria alashanica＋S. breviflora＋Hedysarum polybotrys community, S. breviflora＋Stipa grandis community, S. grandis＋S. bungeana community, Cyperus glomeratus community, S. grandis community and Carex aridula community. The distribution of mountain steppe community was mainly affected by altitude, soil alkali-hydrolyzed nitrogen, water content, available potassium, silt and organic matter contents, with altitude and soil water content having the greatest effects (P<0.01). The Patrick index and phylogenetic diversity index (PD) of plant community showed an increasing trend with the altitude increase, the Shannon index and Pielou index showed a unimodal trend, and the phylogene-tic structure gradually changed from aggregation to dispersion. There was a significant positive correlation between species diversity index and PD index. Shannon index was negatively correlated with net relatedness index (NRI). Plant species diversity and phylogenetic diversity of mountain steppe were mainly affected by soil water content, available potassium, total nitrogen, silt and sand contents. NTI was significantly affected by altitude, while the NRI index was significantly affected by soil silt content.

Fruit quality and yield in orchards will decrease after long-term planting. To analyze the changes of soil quality under different planting years and identify the key factors of the declining of orchard soil quality could provide scientific foundation for optimizing fertilization management of orchard soil. In this study, we analyzed the changes of soil physical, chemical, and biological properties of loquat orchard under different planting years (<10 years, 10-15 years, 15-20 years, ≥20 years) in Ninghai County, Zhejiang Province, and evaluated soil health by using soil quality index, multifunctionality index, and sensitivity and resistance indicators. The results showed that, compared with the orchards planting less than 10 years, soil bulk density in the orchards with planting years of 10-15 years and over 20 years increased by 12.8% and 13.6%, respectively. Soil pH decreased by 8.8%, 8.6%, and 7.5% in the orchards with planting years of 10-15 years, 15-20 years and over 20 years, respectively. With the increase of planting years, soil microbial biomass carbon, soluble organic carbon, soluble organic nitrogen, available phosphorus, available potassium, total organic carbon, total nitrogen decreased, and the soil quality and multifunctionality index of loquat orchard soil decreased. Compared with the orchards planting less than 10 years, soil quality index and soil multifunctionality index decreased by 20.4% and 17.9% for the orchards with the planting years of 10-15 years, 38.1% and 25.2% for the orchards with the planting years between 15-20 years, and 50.7% and 35.5% for the orchards planting over 20 years, respectively. The key factors affecting soil quality of loquat orchards were soil soluble nitrogen, available potassium, and available phosphorus. Amongst the available nutrients, NH₄⁺ and NO₃^- were the sensitive indices in orchard soil. In conclusion, long-term planting decreased soil quality and available nutrient content in loquat orchards.

Estuaries are transitional zones between rivers and marine environments, with intensive human activities. Pollutants pose a threat to the ecological systems of estuaries. Among these pollutants, microplastics and antibiotic resistant genes have gained significant attention due to their potential impacts on estuarine organisms and human health. Microplastics can form unique biofilms, adsorb pollutants from the surrounding environment, and provide potential hosts for antibiotic resistant genes, with positive consequence on horizontal gene transfer of antibiotic resistance. We provided an overview of the pollution status of microplastics and antibiotic resistant genes in estua-rine areas, with a particular emphasis on the influence of biofilms formed on microplastics on the enrichment, transport, and transfer of antibiotic resistant genes. We also highlighted the limitations in current research, regarding microplastic sampling, analysis methods, and inconsistent reporting units. Furthermore, we proposed prospects for the biodegradation of microplastics and potential risk assessment of microplastic biofilms.

To rapidly acquire fiber phenotypic data for wood quality assessment, we used a portable NIR spectro-meter to collect spectral data in 100 individuals of Schima superba at 18-year-old of 20 different provenances, and simultaneously collected wood cores. Wood basic density and the anatomical structure of wood fiber were measured. The standard normal variate (SNV), orthogonal signal correction (OSC), and multiplicative scatter correction (MSC) methods were used for spectral preprocessing, the competitive adaptive reweighted sampling (CARS) method were used for wavelength selection, and the partial least squares regression (PLSR) model were established. The results showed a significant difference for the absolute reflectance data between forest and indoor environments, and the spectral data of which were relatively independent. SNV, OSC and MSC showed significant differences for predictive performance of the model. OSC had the excellent preprocessing capability in multiple cha-racteristics of wood fiber ether in forest and indoor environments. The predictive accuracy of the models with R² was 0.47-0.78 in forest (average=0.63), and R² was 0.54-0.82 in indoor environment (average=0.71). However, the SNV and MSC methods could not establish the models, except the fiber wall-cavity ratio from forest data. After wavelength selection through the CARS method, the predictive accuracy of the models was significantly improved using both forest and indoor data (R²=0.58 and 0.72, respectively). When performed OSC before and after CARS, the predictive accuracy of the models was improved to 0.68 and 0.84 respectively using forest and indoor data. The OSC and CARS could significantly improve the accuracy of the models for wood fiber anatomical structures. First OSC, then CARS, and finally OSC methods could be used to establish the PLSR model for fiber length, fiber cell wall thickness, fiber lumen diameter, wood basic density, fiber cavity-width ratio, and fiber wall-cavity ratio, and the R² ranged from 0.80 to 0.95. These models had effective predictive ability and accuracy to assess the physical properties of wood fibers of S. superba.

Carbon balance of the tree layer in natural forests is affected by three carbon pools: tree growth, morta-lity, and recruitment. However, the dynamics of the sink of each carbon pool and the driving factors are still unclear. To this end, we used stepwise regression method and structural equation model to assess the effects of biotic (stand and diversity) and abiotic (soil, topography and climate) factors on three dynamic processes of carbon sinks, namely, stand growth, recruitment and mortality, in the natural forests of Larix gleminii, based on the data from the seventh and eighth national continuous forest inventory of the Greater Khingan Mountains. The results showed that the average growth, recruitment and mortality of L. gleminii stand were 0.73, 0.17 and 0.41 t·hm^-2·a^-1. The growth of carbon sink in forest stands increased with the slope aspect index (the total path coefficient β=0.135), stand basal area (β=0.132) and slope position (β=0.085), but decreased with the increases of average stand age (β=-0.225) and altitude (β=-0.196). Recruitment was negatively correlated with stand basal area (β=-0.368), average stand age (β=-0.240), soil pH (β=-0.184), soil total phosphorus (β=-0.115) and tree species richness (β=-0.012), and was positively correlated with soil total nitrogen (β=0.258). The larger important factors affecting mortality were the average tree height (β=0.276) > Simpson index (β=0.232) > soil total phosphorus (β=0.195) > stand basal area (β=0.154) > soil pH (β=0.084). Stand age, basal area and average tree height were the most important factors affecting stand carbon sink growth, recruitment and mortality. Topography and soil conditions were also the key to affect stand dynamics. Therefore, the structure and soil conditions of the forest can be adjusted through reasonable thinning in the management process, which in turn promotes the sustained fulfilment of forest carbon sink capacity.

The construction of an ecological security pattern is crucial to maintain ecosystem health and stability, with great significance for regional sustainable development. Following the research paradigm of "ecological source areas-ecological resistance surfaces-ecological corridors", based on the index framework of "sensitivity-importance-connectivity", we identified the ecological source areas, generated the ecological resistance surface through graded weighting of underlying surface factors and point of interest (POI) method, determined the ecological corridor, pinch point, and obstacle area using circuit theory, and constructed the ecological security pattern of Guizhou Pro-vince. Results showed that the areas of extremely sensitive of rocky desertification and soil erosion and the areas of extremely important areas of water resources forming, soil and water conservation and biodiversity in Guizhou Pro-vince were generally small and distributed differently, accounting for 1.6%, 3.7%, 25.2%, 6.1%, and 10.4% of the total area, respectively. The key ecological functional areas of the extremely sensitive to external disturbance, most important in ecosystem service and strongly connective in landscape accounted for 5.3%, 34.2%, and 27.9%, respectively. A total of 210 ecological source areas were identified, covering 27574.38 km² and with an area ratio of 15.6%. The number of the ecological corridor was counted into 463, with a total length of 10049.81 km. The amount of ecological pinch points was 490, while that of the ecological barrier was 117, area of the both were computed into 22.08 and 91.04 km², respectively. Ecologically high-resistance areas were mainly distributed in regions with highly frequent human activities. Based on the above construction, we assessed the ecological security pattern in Guizhou Province, conducted ecological security zoning, and proposed targeted protection and restoration mea-sures. The study could provide scientific references for the spatial planning of land and regional ecological protection in Guizhou Province.