Changes in the seasonal precipitation regime induced by global climate change may alter moisture and the dynamics of related microbes and enzymes, thereby significantly affecting forest litter decomposition; however, the specific mechanisms remain unclear. Hence, a precipitation manipulation experiment including the treatments of control (CK), decreased precipitation in the dry season with extremely increased precipitation in the wet season (IE) and decreased precipitation in the dry season with proportionally increased precipitation in the wet season (IP) was performed from October 2020 to October 2021 in a subtropical evergreen broad-leaved forest in China. The moisture, chemical properties, microbial biomass, enzyme activity, and decomposition rates of two dominant shrub species foliar litter, Phyllostachys violascens and Alangium chinense, were measured at six stages during the dry and wet seasons. The results showed that both IE and IP significantly increased the litter decomposition rates (more than 2.0% for P. violascens and more than 4.7% for A. chinense, respectively), while the effects of IE were the most significant, which was mainly related to the precipitation availability and the frequency of dry-wet cycle. Furthermore, the IE and IP increased the wet season’s contribution to the annual total decomposition regardless of litter species, and more significant effects were also observed in IE. Additionally, the results of structural equation model indicated that the seasonal precipitation regime could regulate the decomposition process directly by changing moisture and the contents of elements and refractory substances, as well as indirectly by influencing the related microbial biomass and enzyme activity. These results deepen the understanding of the biogeochemical cycle in forest ecosystems under the global climate change scenarios.
Coastal wetland resources are abundant in Jiangsu Province.The area of salt marsh has declined since the 1980s,due to human activities(such as reclamation)and the invasion of alien species.Based on Landsat re-mote sensing images and the application of Digital Shoreline Analysis System(DSAS),we examined the variations of the reclamation area and salt marsh vegetation area in the tidal flat vegetation zone of coastal wetlands in Jiangsu Province from 1985 to 2020,the relationships between their changes,as well as the vegetation effects of reclama-tion scale.The results showed that:(1)From 1985 to 2020,the vegetation zone shifted seawards significantly,spatially corresponding an increase of reclamation area.The change hotspot area gradually moved southward,from Sheyang Estuary-Beiling Estuary in 1985 to Liangtuo Estuary-Yaowang Port after 2015.(2)The areas of salt mar-shes and reclamation varied greatly among different bank sections.The ratio of reclamation area to salt marshes in-creased rapidly,increasing from 0.017∶1 in 1985 to 5.59∶1 in 2020.The reclamation area was significantly nega-tively correlated with the salt marsh area.(3)With the gradual decline of the salt marsh vegetation zone,the corre-lation between the area of salt marshes and the extension rate of tidal flat vegetation shifted from significant positive to non-significant,indicating that the scale of salt marsh vegetation area played a certain role in promoting tidal flat vegetation zone extending to the sea.
Water is a key factor limiting the improvement of both quality and yield of walnut industry in arid areas.The effects of different water supply amounts on physiology,growth,and fruit quality of walnut trees remain unclear.We conducted an irrigation experiment with three treatments,i.e.,deficit(DI),conventional(CI),and excess irrigation(EI).We measured leaf hydraulic traits,photosynthetic physiological characteristics,soluble sugar content,leaf area,branch growth,fruit morphology and no kernel or deflated kernel rate at different canopy heights of'Wen 185'walnut trees.The results showed that:(1)Midday leaf water potential decreased significantly with de-creasing irrigation and increasing canopy height.Midday leaf water potential at the upper canopy was significantly lower than that at the lower canopy.(2)Different irrigation amounts did not affect light compensation point,light saturation point,maximum net photosynthetic rate,maximum photochemical efficiency,and chlorophyll SPAD.(3)Irrigation treatments did not significantly affect soluble sugar content of leaves and fine roots,but the soluble sugar content of walnut kernels was significantly increased with decreasing irrigation and accumulated with increas-ing canopy height.(4)Leaf area was significantly decreased and Huber value was significantly increased with the reduction of irrigation.The reduction of irrigation did not affect fruit morphology,but increased the no kernel or deflated kernel rate,with a rate being 87.9％higher in the DI group than in the EI group.The no kernel or deflated kernel rate at the upper canopy was 41.8％higher than that at the lower canopy.Our results indicated that walnut trees resist drought by increasing Huber value and decreasing leaf area to maintain stable photosynthesis,but the hydraulic restriction caused by increasing canopy height will aggravate the drought stress of plants,resulting in an increase in the no kernel or deflated kernel rate.
Habitat selection is the process that animals actively select suitable habitats to escape predators,repro-duce,and forage,reflecting the ecological needs of animals.Land covers and seven habitat variables of Jiangsu Dafeng Milu National Nature Reserve were investigated by unmanned aerial vehicle(UAV)remote sensing and field surveys in spring,summer,and autumn of 2019.The Vanderploeg selection coefficient and Scavia selection index were calculated,and statistical test and principal component analysis were performed.The results showed that:(1)in spring,Pere David's deer preferred to select the habitats of Spartina alterniflora,Imperata cylindrica,and Carex scabrifolia communities with vegetation coverage less than 30％,vegetation density less than 150 plants· m 2,aboveground biomass less than 100 g·m 2,and the distance to water source less than 210 m(P＜0.05);(2)in summer,they preferred the habitats of S.alterniflora and I.cylindrica communities with aboveground bio-mass less than 40 g·m-2(P＜0.05);and(3)in autumn,they preferred to select the habitats of I.cylindrica,S.alterniflora and Suaeda glauca communities with vegetation height less than 4 cm and vegetation density more than 30 plants·m-2(P＜0.05).Key factors affecting habitat selection of Père David's deer in different seasons were feeding factor,food abundance factor,and water source factor,respectively.Through revealing the differences in habitat selection by Père David's deer in spring,summer,and autumn,our results provided the reference for the conservation and restoration of Père David's deer and their habitats in Dafeng Milu National Nature Reserve.
Using artificial water supplementation and natural water control methods,we measured the light response process of photosynthetic physiological parameters of potato leaves under different water conditions and further ana-lyzed the threshold effects for the responses to soil water.Soil moisture was set as 55％,65％and 75％field water-holding capacity for drought stress treatments,80％field water-holding capacity for control treatment and 85％field water-holding capacity for waterlogging treatment.The results showed that net photosynthetic rate(Pn),water use efficiency(WUE),and light response parameters of potato leaves had obvious water critical effects.The apparent quantum efficiency(AQY),maximum net photosynthetic efficiency(Pnmax),and light saturation point(LSP)in-creased first and then decreased with increasing soil water content,while light compensation point(LCP)and dark respiration rate(Rd)first decreased and then increased.Under waterlogging or drought stress,the ability of light absorption and conversion of potato leaves under weak light was reduced,the utilization of strong light and weak light was inhibited,and dry matter accumulation was maintained by reducing respiratory consumption.With increa-sing soil moisture,Pn and WUE increased first and then decreased,but the critical values of moisture were different.The relative soil water content(Wr)at 56.7％was the critical point of stomatal limitation in potato leaves.The Wr at 96.3％was water saturation point of Pn,andWrat 70.1％was the high effiiciency point of WUE.Photosynthetic capacity of potato leaves under waterlogging was higher than that under drought stress.The moisture threshold of po-tato in semi-arid area was determined by mathematical model.The Wr value between 70.1％and 96.3％was high-yield and high-efficiency water,in which the photosynthetic productivity and water use efficiency of potato were higher.Therefore,Wr between 70.1％and 96.3％is suitable for potato growth in semi-arid area.Photosynthetic capacity of potatoes under waterlogged conditions is significantly higher than that under drought stress in semi-arid area.
As an important component of rice production in China,rice-fish co-culture is a model of the combina-tion of rice planting and aquaculture,with a long history and obvious economic,ecological,and social benefits.It has been widely used in different rice-producing regions.We reviewed the development history,distribution area,and main modes of rice-fish co-culture,as well as related fundamental studies in terms of economic benefits,rice yield,growth characteristics,soil and water ecological environments,biodiversity,and greenhouse gas emissions.There are some problems in rice-fish co-culture,including lack of in-depth research,non-standard planting and breeding technology,emphasis on breeding,few suitable rice cultivars,high density of fish breeding.To fully de-velop the production potential of rice-fish co-culture,we proposed development opinions from the aspects of techni-cal training,focusing on rice planting,screening of suitable rice cultivars,and controlling water pollutions,which provides theoretical supports for improving the quality and efficiency of agriculture and its sustainable development.
Coral reef ecosystems provide important economic and ecological benefits,but are threatened by human activities and environmental change.Based on the exposure-sensitivity-adaptability model framework,we estab-lished an assessment index system of coral reef ecological vulnerability by combining survey data with spatial analy-sis of points-of-interest of human activities,and put forward control countermeasures in two Malaysian popular tour-ist islands,Pulau Redang and Pulau Perhentian.The results showed that ecological vulnerability index of coral reefs in the study area ranged-0.30 to 0.66,with an average value of 0.08 and 0.26 for the stations around Pulau Redang and Pulau Perhentian,respectively.The overall vulnerability of coral reefs in Pulau Perhentian was higher than that in Pulau Redang.The highly vulnerable sites were mainly located in the southern part of Pulau Perhen-tian,while the mildly vulnerable sites were in northwest of Pulau Perhentian and eastern Pulau Redang.The results of redundancy analysis showed that salinity and turbidity were the main environmental factors affecting the ecological vulnerability of coral reefs,while resort and passenger terminal were the main human activity factors.Therefore,controlling the distance between recreational facilities and coral reef areas and dividing marine Darks into functional zones would help reduce the vulnerability of local coral reefs,and can be used as alternative strategies for local cor-al reef conservation and management.
Iron is one of the essential nutrients for plants and plays an important role in maintaining wetland ecosys-tem stability and functioning.Here,we analyzed the spatial distribution and influencing factors of soil total Fe con-tent across eight land use types and seven vegetation types in the Yellow River Delta.The results showed that the average content of total Fe in the soil was 24.28 g·kg-1.Among different land use types,the total Fe content was the highest in industrial and mining areas(27.29 g·kg-1)and lowest in forest wetland and bare land(22.55 and 22.56 g·kg-1,respectively).The maximum value of total Fe content occurred in the soils under the Phragmites australis community(27.30 g·kg-1).There were significant differences in total Fe content at 0-10 and 10-20 cm depths across different land use types(P＜0.05).There was no difference in total Fe content between different soil depths for the same land use type(P＞0.05).The total Fe content was significantly positively correlated with soil organic matter,total nitrogen,ammonium nitrogen,and bicarbonate contents at each soil layer(P＜0.01).The content and distribution of total Fe were also closely correlated with soil-forming parent material,soil type,hydro-logical and redox conditions,and human activities.
Understory herbs are the basic components of forest ecosystem,which play a vital role in forest regenera-tion,as well as in the maintenance and improvement of ecosystem structure and function.Understanding the com-munity characteristics and influencing factors of herbaceous layer in the understorey is helpful to construct an ideal forest-grass combination model.In this study,the undisturbed Larix gmelinii var.principis-rupprechtii plantations,the thinned L.gmelinii var.principis-rupprechtii plantations,and the natural mixed forest of L.gmelinii var.princip-is-rupprechtii and Betula platyphylla in Jingyuan County of the south mountainous area of Ningxia were examined.We explored the relationship between community characteristics(i.e.,species diversity and community biomass)of understory herbs,soil properties(i.e.,soil bulk density,water content,total carbon content,total nitrogen content and total phosphorus content)and stand structure(i.e.,stand density and canopy density).The results showed that:(1)Compared with the monoculture plantations,the natural mixed forest had more herbaceous species(34 species),higher species diversity and aboveground biomass;(2)Soil properties under the natural mixed forest were better than those under the plantations,but soil properties under the thinned plantation were significantly improved than those under plantation without human disturbance;(3)Redundancy analysis showed that species diversity of herbaceous layer was positively correlated with soil water content,soil total carbon content,total nitro-gen content,and total phosphorus content,but negatively correlated with soil bulk density,stand density and cano-py density.Stand density and soil water content of 0-20 cm soil layer significantly affected species diversity of understory herbs(P＜0.05);(4)The regression analysis showed that soil properties of 0-20 cm layer,species richness and dominance,stand density and canopy density significantly affected aboveground biomass of herbaceous species(P＜0.05).The random forest model and variance decomposition further showed that the explanation rate of soil factors on aboveground biomass was 30.99％,among which soil bulk density,total carbon content,total nitro-gen content and soil water content of 0-20 cm layer were the most important ones.The explanation rate of stand structure was 12.74％,of which stand density was the most important explanatory factor.The explanation rate of species diversity was only 3.42％.The natural mixed forests as the most ideal model of forest-grass combination were conductive to the healthy development of understory herbs and the improvement of understory ecological environ-ment.Species diversity and aboveground biomass of herbaceous layer were affected by different environmental fac-tors.Our results provide references for the near-natural management of plantations(such as thinning and replan-ting)and the high-quality development of understory economy.
To understand the responses of phytoplankton functional groups to connectivity and heterogeneity in the connected river-lake system of Guangzhou Haizhu National Wetland Park,we conducted a quarterly survey on the phytoplankton community structure and environmental characteristics in the Shiliugang River and Haizhu Lake in 2021.A total of 168 phytoplankton species belonging to 6 phyla and 76 genera were detected,mainly consisting of Chlorophyta,Bacillariophyta,Euglenophyta,and Cyanophyta.The average abundance of phytoplankton in Haizhu Lake(64.76×106 cells·L-1)was significantly higher than that in Shiliugang River(24.09×106 cells·L-1)(P＜0.05),while Shannon diversity index and Pielou evenness index in the Shiliugang River were significantly higher than those in Haizhu Lake(P＜0.05).The phytoplankton in the connected river-lake system of Guangzhou Haizhu National Wetland Park could be classified into 28 functional groups according to their ecological functions.The dominant functional groups were group Lo,group J,and group P,which was represented by Merismopedia,Scenedesmus,and Aulacoseira,respectively.Water temperature,ammonium nitrogen,and total phosphorus were the main environmental factors affecting the dominant functional groups.The results indicate that the connected river-lake system has reached the level of eutrophication.
Under the supports of ENVI and ArcGIS software,seven Landsat remote sensing images in July of 1991,1996,2001,2006,2011,2016,and 2021 were selected as data sources to construct landscape type maps of Yellow River Delta.Using the methods of land use dynamic degree,human activity intensity model,and Pearson correlation coefficient,we evaluated the spatial and temporal variations of land use types,human activity intensity,and their relationship in coastal wetlands of the Yellow River Delta in the recent 30 years.The results showed that:(1)There were small fluctuations for the area of the Yellow River Delta in recent 30 years.The annual change rates of natural wetland,artificial wetland,and non-wetland areas were-1.52％,15.17％,and 1.95％,respectively.(2)Land use in the Yellow River Delta changed from single type to diverse types.The largest value(3.28％)of the dynamic degree of synthetic land use appeared during 2011-2016.(3)The equivalent area of construction land and the human activity intensity index of the Yellow River Delta showed an increasing trend in study period.The equivalent area of construction land increased from 212.33 km2 to 501.26 km2,and the human activity intensity index increased from 7.93％to 18.84％in recent 30 years.(4)The spatial-temporal pattern of land use/cover change was consistent,synchronized,and significantly correlated with human activity intensity,suggesting that human activity was closely related to land use change in the study area.
A rational assessment of landscape ecological risk(LER)in the ecological restoration region of loess hills in northern Shaanxi is crucial for optimizing regional landscape pattern and maintaining ecosystem function.Landscape pattern index and GIS spatial analysis were used to demonstrate the level and spatial-temporal evolution pattern of LER using data from land use of Yan'an from 2000 to 2020.The results showed that:(1)The landscape ecological risk index(ERI)was in the range of 0-0.449,with low,medium-low,and medium risk areas domina-ting risk grades that were patchily dispersed in the southwest,along the Yellow River,and northwest.The high-risk area was centered in the Baota district.In 2020,the area of high and medium-high risk regions increased by 1.27x 104 hm2 and 25.25×104 hm2 compared to 2000,respectively,with a notable expanding tendency of LER.(2)From 2000 to 2020,Moran's I of LER was positive,with a significant geographic correlation.The main spatial aggrega-tion modes of LER were"high-high"and"low-low",but the spatial aggregation initially strengthened and then declined,and the local difference gradually became prominent.(3)The LER hotspots were located in the Baota region,where built-up construction land and farmland predominated,with substantial system disturbance and frac-tured and split landscape,indicating a high-value agglomeration pattern.The LER cold spots were primarily located in Huanglong,Huangling,and Fuxian counties,where the high regional altitude and large patch area of forest and grassland were responsible for the low intensity of human disturbance and the low degree of landscape separation and fragmentation,resulting in a low-value agglomeration pattern.In the past 20 years,the area of the cold-hot spot regions changed dramatically,and its distribution pattern shifted frequently.Consequently,LER in Yan'an was rel-atively low,with variations of risk levels,spatial agglomeration patterns,and cold-hot zones.Land use structure should be planned to promote the security and stability of landscape.
To provide scientific basis for rational utilization of green manures in dryland cropping systems,we examined the characteristics of decomposition and nutrient release of green manure.Four types of green manures(including crimson clover,vetch,ryegrass and oat)were used for on-site decomposition incubation and their impacts on soil organic carbon and total nitrogen and crop yield were investigated in a spring maize system.All green manures decomposed rapidly in 0-14 d after incorporation,while the decomposing rate slowed down after six weeks.On the 42 d after the incorporation,the cumulative decomposition was more than 55％for all green manures,with a carbon releasing rate of 59.79％-74.75％and a nitrogen releasing rate of 60.79％-76.61％.On the 130 d after the incorporation,the cumulative decomposition rate was greater than 60％for all green manures,which was higher for leguminous green manure than gramineous green manure.Incorporation of green manures increased the contents of soil organic carbon and total nitrogen.Compared to the control without green manure,the incorporation of green manures increased maize yield by 2.21％-7.06％,with stronger effects of the leguminous green manures than gramineous green manure.In conclusion,leguminous green manure is more suitable for soil health and crop production in dryland cropping systems in northwest China.
Water use efficiency(WUE)is an important indicator to link the coupling between ecosystem water and carbon cycles.Understanding the spatiotemporal variation of ecosystem WUE and its influencing factors is essential for optimizing the integrated management of regional water and carbon resources and improving ecosystem producti-vity.With remote sensing data from MODIS,meteorological data from CRU,and land use data from CCI,the spa-tial distribution and temporal variations of ecosystem WUE in Ili River-Balkhash Lake Basin were investigated by using MK test and Sen's trend analysis.The factors influencing WUE were further detected by partial correlation analysis.The results showed that the multi-year average values of annual,spring and autumn WUE illustrated same change patterns from the southeast to northwest,with a trend of increasing at first,then decreasing,and increasing at last.However,WUE values in summer displayed an opposite spatial variation as described above and WUE val-ues of most areas in winter were close to zero.WUE values were highest in summer,followed by spring,autumn,and winter.Theaverage annual WUE value over the whole basin increased slightly with time,with significantly increasing annual WUE in the lower reaches.The summer WUE values decreased with time in more than 90％of the basin,especially in the areas near Balkhash Lake,Ili River Valley,and Tianshan Mountains.Moreover,the annual WUE values in the upper reaches of the basin were obviously higher than those in the middle reaches,and the annual WUE values were lowest in the lower reaches of the basin.The interannual variations and trends of annu-al WUE values in the upper,middle and lower reaches of the basin were not significant.The rank of summer WUE values in the upper,middle and lower reaches of the basin was absolutely reverse to that of annual WUE values.The summer WUE values in the upper and lower reaches of the basin showed a significant decreasing trend,while the decreasing trend in the middle reaches of the basin was not significant.The intra-annual distribution of WUE in the basin was extremely uneven,with a peak value in August.In terms of influencing factors,gross primary produc-tivity and precipitation showed stronger influences on WUE than evapotranspiration and temperature,respectively.
Systematically understanding the spatiotemporal variations of vegetation coverage and driving factors on the Qinghai-Tibet Plateau can provide scientific basis for ecological sustainable development.By integrating MODIS normalized difference vegetation index(NDVI),land surface temperature and meteorological data,we explored the spatiotemporal variations of vegetation coverage and the relationships with the factors of precipitation,temperature,and human activities on the Qinghai-Tibet Plateau from 2001 to 2020,using dimidiate pixel model,trend analysis,partial correlation analysis,and residual analysis.Vegetation coverage on the Tibetan Plateau showed a fluctuating upward trend from 2001 to 2020,and increased spatially from northwest to southeast.There were positive correla-tions between vegetation coverage and climate factors,with complementarity between the effects of precipitation and temperature.There was a negative correlation between vegetation cover and surface temperature.The rise and fall amplitudes of land surface temperature were higher than that of air temperature.Air temperature was more likely to be a factor limiting the growth of vegetation.The areas where human activities have improved vegetation cover were mainly located in north-central Qinghai and north of Ngari.The degraded areas included some grassland areas of central-eastern Yushu and parts of Nagqu and Lhasa.
The distribution characteristics of soil nutrients in Picea schrenkiana forest were analyzed,and the com-prehensive index of soil fertility(IFI)was calculated through principal component analysis to evaluate soil fertility levels under different altitudes,stand ages,and canopy densities,with the aim to provide a theoretical basis for sci-entific management of soil resources in Picea schrenkiana forest.The results showed that:(1)soil carbon and nitro-gen contents in 0-20 and 20-60 cm soil layers in Picea schrenkiana forest under different altitudes were 1900-2100 m＞2500-2700 m＞1700-1900 m＞2300-2500 m＞2100-2300 m.Soil carbon and nitrogen contents of 0-20 cm at the 1900-2100 m were significantly higher than those of 2100-2300 m(P＜0.05).The IFI under this altitude was the highest(0.45),of which 63％of sampling plots reached grade Ⅰ(high)and grade Ⅱ(relatively high)in soil fertility,indicating that soil fertility was generally good in the range of 1900-2100 m.(2)Soil carbon and nitrogen contents showed an increasing trend with increasing stand age,with significant difference(0-20 cm soil layer)among mature forest,young forest,and middle-aged forest(P＜0.05).The IFI of mature forest was 0.41,of which 54％of sampling plots reached grade Ⅰ(high)and grade Ⅱ(relatively high)in soil fertility.(3)Under the condition of high canopy density(＞0.6),soil carbon and nitrogen contents in 0-20 cm soil layer was significantly higher than those under the condition of low canopy density(P＜0.05),the IFI under high canopy density was higher(0.37),and 38％of sampling plots reached grade Ⅰ(high)and grade Ⅱ(relatively high)in soil fertility,but there was no significant difference.Taken together,the carbon and nitrogen contents in the surface soil of Picea schrenkiana forest were significantly affected by altitude,stand age,and canopy density,while the IFI was significantly affected by altitude and stand age.
We evaluated the effects of dam interception on sulfur cycle in Longtan Reservoir,a deep-water reservoir in the upper reaches of the Pearl River.Water samples were quarterly collected from tributaries,stratified water and underflow water in April,July,October 2019 and January 2020.Hydrochemical parameters,SO42-concentrations and isotopic compositions(834SSO4 and 818OSO4)in water samples were analyzed.Based on redundancy analysis and Bayesian stable isotope mixing model,we examined the impacts of altered hydrodynamic conditions under the influ-ence of damming on sulfur cycle in the water column of Longtan Reservoir.The results showed that the main source of SO42-was sulfide oxidation(with O2 or Fe3+as electron acceptors),and also included atmospheric precipitation and anthropogenic sources.After damming and impoundment,the fluctuation range of SO42-concentration and 834SSO4 and δ18OSO4 values in the water column significantly increased.Water storage after dam impoundment led to an increase in relative water column stability(RWCS),which significantly enhanced sulfide oxidation and sulfate reduction in the reservoir.Thus,RWCS is an important hydrodynamic factor driving the sulfur cycle in the reser-voir.This study is helpful to further understand hydrodynamic mechanisms driving sulphate transport and transfor-mation processes in reservoirs,providing a theoretical basis for the scientific utilization and protection of water resources in deep-water reservoirs.
To clarify the effects of different temperatures and parental reproductive ages on the offspring color morph differentiation,the newly-born first-instar nymphs of the red and green pea aphid(Acyrthosiphon pisum)on the 2nd,7th,and 12th parental reproductive age from F0-F5 were continuously raised for five generations at three tem-peratures(15,22,and 26 ℃).Results showed that temperature and parental reproductive age had a significant effect on the offspring color morph differentiation.Red color morph A.pisum tended to produce green color morph offsprings at 15 ℃,while green color morph A.pisum tended to produce red color morph offsprings at 26 ℃.The proportion of non-parental color morph offspring produced by red and green parents at 22 ℃ was significantly lower than that at 15 and 26 ℃(P＜0.05).Furthermore,different parental reproductive age also had a certain effect on the offspring color morph differentiation.The parental reproductive age affected the proportion of color differentiation and the time of color differentiation in the offsprings of pea aphid(P＜0.05),indicating that the onset of color dif-ferentiation in the offsprings of red and green pea aphid was related to different parental reproductive ages at the same temperature.
Understanding the spatiotemporal variation of ecosystem services and their drivers is important for the ecological protection and high-quality development in the Yellow River Basin.Based on InVEST model,we analyzed five ecosystem services in the Yellow River Basin from 1990 to 2019,i.e.water yield,water purification,carbon storage,soil conservation and habitat quality.GeoDetector model was used to explore the driving forces.Results showed that:(1)During the study period,water yield and soil conservation fluctuated with an overall rising trend,while water purification,carbon storage,and habitat quality were generally stable.Spatially,water yield was higher in the south and lower in the north,and soil conservation was higher in the hinterland and lower in the north and the two ends.The spatial distributions of water purification,carbon storage,and habitat quality services were rela-tively similar,which was lower in the Hetao Plain,Ningxia Plain,Fenwei Plain,and Henan-Shandong basin.(2)All the five ecosystem services showed significant global autocorrelation and spatial heterogeneity.In terms of local heterogeneity,water yield,water purification,and habitat quality obviously displayed three cluster types:high-high,low-low,and insignificant clustering,while other two services showed no local clustering.(3)Climatic and geographical factors were the main drivers of water yield and soil conservation changes,among which annual preci-pitation and slope were the most important.Land use and land cover(LULC)was the key factor affecting water purification,carbon storage,and habitat quality.
The dominant factors affecting plant growth vary across the stages of life history.Understory microhabitats play a significant role on plant growth and development during juvenile stage.In 2021,we surveyed Phellodendron amurense saplings planted in 2014 beneath a natural forest in Baihuashan Nature Reserve,and measured the biotic factors(density of con-and heterospecific seedling neighbors,density of herbaceous and shrub neighbors,and adult neighborhood index)and abiotic factors(leaf area index,soil nutrients,and microtopography indices)around the saplings.Linear mixed models were used to assess the effects of biotic factors and abiotic microhabitat factors on the growth rates of the established saplings.The results showed that both biotic and abiotic factors affected the growth of P.amurense saplings,with different magnitudes in their impacts.Heterospecific adult neighbors had the most significant negative effect on the growth of saplings,explaining 34.1％-47.7％of the variance in their growth.Light intensity also had a negative effect,which explained 18.1％-25.3％of the variance.Soil nitrogen,available potassium,and organic carbon promoted the crown extension of P.amurense,accounting for 21.1％of the variance of the growth.Among the microtopographic factors,the topographic wetness index had a significant positive impact on the growth of saplings,explaining 19.5％of the variance,whereas slope had a negative but weak effect on the growth,accounting for 11.5％of the variance.Shrubs and grasses and the conspecifics did not affect the growth of P.amurense saplings.In conclusion,deciduous broad-leaved forests with flat microtopography,moist and fertile soil,rich in nitrogen and potassium,and high canopy density would facilitate the ex situ conservation of P.amurense.
