应用生态学报最新文献

Soil organic carbon turnover and stabilization are closely related to nitrogen deposition and litter decomposition. However, there are great uncertainties about how the decomposition of bamboo litter driven by nitrogen deposition affects soil organic carbon components. To investigate the effects of nitrogen deposition-driven litter decomposition on soil organic carbon components, we conducted an experiment at the Anji Moso bamboo ecosystem research station of Zhejiang A&F University with nitrogen treatments (N, 50 kg N·hm^-2·a^-1; CK, control with equal amount of water) and litter treatments (L, litter retention; LR, litter removal) to analyze changes in litter mass loss, soil physicochemical properties, particulate organic carbon (POC), mineral-associated organic carbon (MAOC), and soil extracellular enzyme activity (EEAs). The results showed that nitrogen application significantly reduced the mass loss of leaf litter. Nitrogen application significantly increased POC content and decreased MAOC content, but litter retention significantly increased the contents of POC and MAOC in soil. Nitrogen application significantly decreased the activities of β-1,4-glucosidase (BG), β-1,4-xylosidase (BX), cellobiohydrolase (CBH), β-1,4-N-acetyl-glucosaminnidase (NAG), phenol oxidase (POX), and peroxidase (PER), while litter retention significantly increased the activities of BG, POX, and PER. Results of correlation analysis and random forest analysis showed that the key factors affecting the decomposition of Moso bamboo litter under nitrogen treatment were BG, PER, pH, microbial biomass carbon (MBC) and POX. Through redundancy analysis (RDA) and regression fitting analysis, we found that POC was significantly negatively correlated with mass loss, MBC, BG, CBH, POX and PER, and significantly positively correlated with ammonium nitrogen (NH₄⁺-N) and nitrate nitrogen (NO₃^--N). MAOC was significantly positively correlated with mass loss, pH, MBC, CBH, NAG, POX and PER, and negatively correlated with microbial biomass nitrogen (MBN). In conclusion, nitrogen deposition inhibits bamboo leaf litter decomposition by reducing extracellular enzyme activities, thereby increasing soil POC content and decreasing MAOC content.

Soil salinization is a common factor constraining agricultural production safety, achieving rapid and accurate acquisition of cultivated land soil salinity information is of paramount importance for ameliorating and resolving soil salinization problems. In this study, with unmanned aerial vehicle (UAV) hyperspectral remote sensing data as the data source, we selected feature band subsets using various spectral transformation data based on different land use statuses of cultivated land, to compare the model accuracies of Support Vector Machine (SVR), Back Propagation Neural Network (BPNN) and Random Forest regression (RFR), and propose the optimal inversion model for regional cultivated land soil salinity. The results showed that the inversion model combining first-order differential spectral transformation data with RFR achieved the highest accuracy. Extracting feature bands separately for cultivated land with different land use statuses would ensure a higher overall model accuracy, with a coefficient of determination of 0.885, a root mean square error of 0.413, and a ratio of performance to deviation of 4.208. Our results could provide a reference for achieving high-precision inversion of soil salinity in cultivated land by UAV hyperspectral technology, and offer scientific support for the prevention and control of soil salinization in cultivated land.

To elucidate the regulatory effects of decaying coarse woody debris on soil carbon and nutrient balance, we measured soil organic carbon, nitrogen, and phosphorus contents and stoichiometric ratios in the topsoil (0-10 cm) beneath Minjiang fir (Abies faxoniana) coarse woody debris of decay classes Ⅰ-Ⅴ, with diameter of 10-30 cm and 30-50 cm in a subalpine coniferous forest. Areas without coarse woody debris situated at least 1 m away from the debris were set as control. The results showed that decaying coarse woody debris significantly increased contents of soil organic carbon (114.1%-412.2%) and nitrogen (0.1%-198.0%), as well as C/N (61.7%-117.1%), C/P (379.6%-931.1%) and N/P (206.3%-532.6%) in soils, but significantly udecreased soil phosphorus content by 28.1%-70.9%. The effects of coarse woody debris on soil organic carbon, nitrogen, and phosphorus content varied with decay classes and diameters. The content of organic carbon and nitrogen in soils beneath large diameter coarse woody debris at decay classes Ⅲ and Ⅳ were significantly higher than those beneath coarse woody debris with small diameter. Soil phosphorus content beneath large diameter coarse woody debris at decay class Ⅲ was significantly higher than that beneath small diameter. Moreover, ecological stoichiometric ratios in soils beneath large diameter coarse woody debris exhibited significant correlations with organic carbon, nitrogen, and phosphorus content of coarse woody debris. In conclusion, retaining larger diameter coarse woody debris with medium to highly decayed classes on the forest floor is beneficial for soil nutrient balance.

Inland lakes are important surface water resources in arid Central Asia. Due to the superimposed influence of natural factors and human factors, the hydrological characteristics of arid lakes show significant temporal and spatial variations. However, data shortage in this area makes it difficult to carry out detailed and long-term quantitative monitoring of hydrological regimes for different lakes. Based on the Google Earth Engine Platform (GEE), we firstly selected the Landsat 5/7/8 remote sensing image data that completely covered the Saram Lake and Ebinur Lake during 1990-2021, and used the multi-remote sensing index decision tree method to extract the continuous long time series of lake area. Combined with lake water level extracted by CryoSat-2 and ICESat-2 alti-meter satellites, we constructed the storage capacity curve based on the relationship between lake area and water level, and estimated the water volume change information of the lakes. Finally, combined with the hydrological, climate and population factors data of the basin, the correlation analysis and random forest method were used to quantitatively compare and analyze the factors of water quantity variation between the two lakes. The results showed that both Saram Lake and Ebinur Lake had expanded during 1990-2021, though with quite different water conditions. The area of Saram Lake increased by only 1.3%, with little interannual variation. The water volume increased by 1.12 km³ at a growth rate of around 0.04 km³·a^-1. Conversely, the area of Ebinur Lake experienced a 30.1% expansion and exhibited significant annual fluctuation, averaging approximately 0.01 km³·a^-1. Annual precipitation and glacial meltwater were the main factors affecting the water content of the Saram Lake, with contribution rates of 33% and 27%, respectively. However, temperature and precipitation were the main factors affecting the water quantity change of Ebinur Lake, and their contribution rates in the process of water quantity change were both 28%. The aim of this study was to use remote sensing technology to reveal the characteristics of lakes' dynamic change and the difference of its response to their external environment in arid areas with the shortage of measured data, which would provide scientific reference for lake ecological environment and water resources protection in arid areas.

Solar-induced chlorophyll fluorescence (SIF) has been widely used in different area, such as estimating forest gross primary productivity (GPP), monitoring drought, estimating evapotranspiration and tracking vegetation phenology. Based on the Global OCO-2 SIF product (GOSIF) and the standardized precipitation evapotranspiration index (SPEI) at different temporal scales (1, 3, 6, and 12 months), we explored the responses of forest photosynthesis to dry-wet change over eastern monsoon China during 2001-2021. The results showed that there were differences in drought intensity and frequency among forests in different geographical regions. Forests in the North China and East China experienced higher drought intensity, while the southern part of Northwest China had lower drought intensity. Forests in the North China experienced more frequent droughts, while the Northeast China and Southwest China had lower drought frequencies. About 74.1% of the area where forest GOSIF was significantly and positively correlated with SPEI, and the response of photosynthesis to SPEI showed the most pronounced at the 1-month scale. In different geographical regions, photosynthesis in the Northeast China was the most sensitive to SPEI, whereas in the North China it was the least sensitive. The drought resistance of forests in the southern part of Northwest China exhibited the strongest, while in the Northeast China it was the weakest. Meanwhile, in different forest types, deciduous broad-leaved forests were the most sensitive to SPEI, followed by mixed forests, evergreen broad-leaved forests, evergreen needle-leaved forests and deciduous needle-leaved forests. Evergreen needle-leaved forests had the strongest resistance to drought stress, followed by deciduous needle-leaved forests, evergreen broad-leaved forests, deciduous broad-leaved forests and mixed forests. During the growing season (May-September), the response sensitivity of photosynthesis to SPEI was strongest in June and weakest in July. Dry-wet changes at the 1 and 3-month scales exerted the main impact on photosynthesis, while in the mid-season (June-August) and late season (September), the impact of dry-wet changes at the 6 and 12-month scales on photosynthesis increased.

Exploring the spatiotemporal variations and response characteristics of global vegetation and extreme climate is of great significance for addressing global climate change and improving ecosystem stability. Based on ERA5 climate data from the European Centre for Medium-Range Weather Forecasts and MODIS normalized difference vegetation index (NDVI) data, we used Sen's trend analysis, correlation analysis, and random forest regression model to explore the responses of NDVI of five vegetation types (boreal and temperate forest, tropical forest, other woody vegetation, grassland, and cropland) to 23 extreme climate indices from 2001 to 2020. The results showed that global NDVI showed an overall increasing trend from 2001 to 2020. The areas with the most significant growth trend was boreal and temperate forest, and the least significant growth trend occurred in cropland. In terms of extreme climate index, except for a few extreme high temperature and low temperature indices, the other indices showed an increasing trend. Across different vegetation areas, the extreme climate index that had the greatest influence on NDVI was different. The results of correlation analysis showed that the indices with the greatest impact on NDVI in the boreal and temperate forest, tropical forest, other woody vegetation, grassland, and cropland were cold days, ice days, annual total precipitation, annual total precipitation, and annual total precipitation, respectively. The results of random forest analysis showed that the indices with the greatest impact on NDVI in each vegetation zone were cold days, warm night days, frost days, warm days, and the cold spell duration index, respectively. The reason for the different results between the two methods was that correlation analysis only reflected linear relationships between variables, while the random forest regression model could capture more complex nonlinear relationships. Our results showed that the response of global vegetation to extreme climate had significant regional differences and complexities, which may result from interactions between different climate factors.

Plant genome size, the sum of the DNA content of a complete set of haplo groups within a given plant species, is an important aspect of biological characterization. There is abundant genome size diversity in eukaryotes. Plant genome size is closely associated with a range of functional traits from the nucleus to individual level, exerts a vital role in shaping plant functional traits, and helps plants present different response strategies to environmental variables. We viewed the relationship between plant genome size and functional traits, such as cell size, stomatal size and density, photosynthetic functional traits, cell cycle, and seed mass. Their response and adaptation mechanisms to environmental variables, such as temperature, precipitation, altitude, nutrients, and heavy metal pollution, were discussed. Finally, the combination of genome size with functional traits and environmental adaptations was encouraged to deeply explore the response and adaptation mechanisms of plants to environmental changes in the context of global change.

We investigated the effect of single seed directional sowing on the growth and development of peanut hypocotyl, plant photosynthetic performance, dry matter accumulation, senescence characteristics and yield of a peanut variety, Huayu 25. There are several treatments in the experiment, including single-seed random sowing (RS), radicle down (RD), radicle flat (RF) and radicle up (RU) treatments, with double seed sowing cleaning stem base soil (QK) as the control. The results showed that under the condition of single seed directional sowing, RD could increase the growth rate of peanut hypocotyl, shorten the emergence time, increase the emergence rate and cotyledon emergence rate, and had faster plant growth rate, higher leaf area index in the early stage of peanut growth, and an increased dry matter accumulation. The pod yield under RD was 8.1%, 14.4%, and 18.1% higher than that of RF, RS, and RU, respectively. Furthermore, RD significantly increased soluble protein content and the activities of superoxide dismutase, peroxidase and catalase, and reduced malondialdehyde (MDA) accumulation. Compared with QK, the soluble protein content, superoxide dismutase, peroxidase and catalase activities of RD in different periods were increased to varying degrees, while the MDA content was decreased, and there was no significant difference in pod yield. Our results suggested that RD could reduce the emergence time and the competition between plants, promote the growth of seedlings, accelerate the formation of seedling morphology, so as to establish a reasonable population structure, enhance the photosynthetic efficiency and dry matter production capacity of the population, effectively delay the aging process of the crop in the later stage, and finally increase pod yield.

We explored the differences in the impacts of drought events on Pinus sylvestris var. mongolica of different ages (30 and 40 years) and different diameter classes (large 20-24.9 cm, medium 15-19.9 cm, small 10-14.9 cm) in the Saihanba Nature Reserve. Based on the tree ring width index (RWI), we analyzed the correlation between radial growth and climatic factors and their ecological resilience to drought events. The results showed that the RWI of 30-year-old small-diameter trees was significantly positively correlated with standardized precipitation evapotranspiration index (SPEI) from September to December of the previous year and February of the current year. RWI of 30-year-old large-diameter and medium-diameter trees was correlated with SPEI from September of the previous year to June of the current year, but the correlation was statistically non-significant. The RWI of 40-year-old large-diameter trees was significantly negatively correlated with the maximum mean temperature in October of the previous year and June of the current year, as well as the mean temperature in June of the current year. The RWI of 40-year-old medium-diameter trees was significantly negatively correlated with the maximum mean temperature and mean temperature in October of the previous year and significantly positively correlated with SPEI in July of the current year. The RWI of 40-year-old small-diameter trees was significantly positively correlated with SPEI from September of the previous year to June of the current year. The resistance of radial growth of trees with different ages to four drought events (40 years old significantly higher than 30 years old) and the resilience exhibited a significant downward trend, while the recovery showed a significant upward trend (40 years old significantly lower than 30 years old). Within the same age group, the responses of P. sylvestris var. mongolica with different diameter classes to drought events were different. The resistance and resilience of large and medium diameter classes of 40-year-old trees were significantly higher than those of small diameter class trees, but their recovery showed no significant difference. For 30-year-old trees, there were no significant differences in resistance, recovery, or resilience among different diameter classes. P. sylvestris var. mongolica of different ages and diameter classes experienced varying degrees of drought stress, resulting in a significant decrease in resilience. The 40-year-old trees exhibited high resistance, while the 30-year-old trees showed high recovery capability. Small diameter class trees were most severely affected by drought stress.

Tree heart rot is widespread in forests, which could affect forest health and bring uncertainties in the estimation of forest carbon sequestration. However, the impacts of heart rot on radial growth of trees are not well understood. Tree-ring data from heart-rotted and healthy trees of Abies georgei var. smithii at altitudes of 3700 m (low-altitude), 4000 m (mid-altitude), and 4300 m (high-altitude) in the Sygera Mountain region of southeastern Xizang were used to compare radial growth and its relationship with climatic factors. The results showed that the positive effect of rapid warming on the radial growth of heart-rotted A. georgei var. smithii in mid- and high-altitude regions was lower than that of healthy trees, while the negative effect on the growth of low-altitude heart-rotted trees was higher than that on healthy trees. In both periods before and after warming, the radial growth rates of heart-rotted trees at all three altitudes were significantly lower than those of healthy ones. With the occurrence of heart rot, the effect of temperature on the radial growth of low-altitude A. georgei var. smithii shifted from promotion to some degree of inhibition. The sensitivity of heart-rotted trees in mid-altitude regions to temperature factors during the previous year's growing season was lower than that of healthy trees, while the sensitivity of heart-rotted trees in the treeline area to temperature was only slightly different from that of healthy trees. Under the background of future climate warming, warming would promote the radial growth of A. georgei var. smithii in the region, and exacerbate the differences in growth rates between heart-rotted and healthy trees.