The Eurasian beaver(Castor fiber Linnaeus,1758)can be considered a hydrological ecosystem engineer as it shapes environmental characteristics through its building activities and feeding behaviour.Even if several studi...The Eurasian beaver(Castor fiber Linnaeus,1758)can be considered a hydrological ecosystem engineer as it shapes environmental characteristics through its building activities and feeding behaviour.Even if several studies have so far reported beaver impact on multi-taxon biodiversity and forest regeneration,there is a lack of research on forest stand structure evolution following beaver direct activity on trees.This represents a pivotal topic for predicting restoration outcomes and reccommending sound silvicultural and management practices to maintain specific forest conditions.Specifically,the study aims at investigating forest stand structure and tree species diversity changes considering river variability,distance from the riverbank and beaver's gnawing activity intensity.The Eurasian beaver is only recently recolonising the three analysed Mediterranean rivers,but stand structure seems to be already significantly impacted by the species.The number of trees was reduced,increasing mean diameter at breast height at stand level,as most of the youngest and/or smaller trees are entirely cut down.Strongest structural variations can be detected in intensively impacted stands and in the forest portions closer to the riverbank.The absence of a significant effect on most of the diversity indices is likely due to the initially homogeneous composition of the tree layer in each stand and to the limited variety of beaver's diet within the sites.Future resprouting of secondary tree shoots,as well as beaver gnawing activity changes in intensity over time and space,can further produce variations in structural parameters and woody species diversity in the medium-and long-term period.Therefore,it will be crucial to further monitor the long-term effects,as structural shifts can produce significant effects on riparian ecosystem functions.展开更多
The distance from the river is a crucial factor that affects the structure and function of desert riparian forests,impeding their regeneration and biodiversity due to water conditions.However,few studies have confirme...The distance from the river is a crucial factor that affects the structure and function of desert riparian forests,impeding their regeneration and biodiversity due to water conditions.However,few studies have confirmed the long-term variation in structure and function of this azonal riparian forest type caused by water stress.We hypothesize that a complex and diverse stand structure is associated with the distance from the river,and tree size plays a crucial role in establishing random frameworks for stability in forest stands.Our investigation was conducted in the lower Trim River.Based on long-term observation from 2005 to 2023,both stand structure parameters and diversity index were used.The variation in stand structure was analyzed using the least significant difference,and stand stability was assessed using Gaussian distribution and bivariate regression methods.Our study indicated that there were no significant differences in the response of size differentiation and crowding to distance from the river.However,a significant divergence in spatial pattern was observed at greater distances from the river,which became more pronounced over time.Regardless of the distance from the river or time-scale,there were significant differences in DBH,crown diameter and length.Furthermore,structural diversity exhibited varying trends with distance from the river and time-scale,indicating a diverse and complex pattern in stand structure due to water stress.The proportion of random frameworks for stability is influenced by the distance from the river,and tree size,especially crown diameter and length,plays an important role.Our research examines the multiple relationships among water conditions,forest structure,and function in an arid region,highlighting the significance of water conditions in the natural restoration of desert riparian forest ecosystems.The findings provide new insights for further exploration of the relationship between stand structure and stability,enhancing our understanding of the theory of random frameworks-stability.Overall,the study provides scientific guidance for sustainable forest management and conservation in the context of a changing climate,particularly regarding water stress.展开更多
Complex hydrological regimes and rugged topography in mountainous cities have increasingly compromised urban riparian zones,presenting marked restoration challenges.This study conducted restoration trials along the Ji...Complex hydrological regimes and rugged topography in mountainous cities have increasingly compromised urban riparian zones,presenting marked restoration challenges.This study conducted restoration trials along the Jiulongtan riparian zone,located in the upper reaches of the Yangtze River(URYR),China.It featured 2 major ecological engineering interventions:(a)establishing semi-natural meadows and applying braided branched meshes to the riparian slope revetment and(b)constructing littoral woods and managing microtopography and sediment in the floodplain area.Furthermore,emergy evaluation was utilized to gauge the effectiveness of these restoration strategies and to assess the sustainability of the reconstructed riparian ecosystems.The following results were obtained:(a)Both the restored slope revetment(RSR)and restored floodplain(RF)ecosystems achieved a state of performance equilibrium after their implementation,with the former benefiting from renewable energy investments and the latter effectively utilizing local resources;(b)service yield outcomes highlighted significant enhancements in species diversity within the reconstructed ecosystems;plant diversity emerged as the primary contributor to total service yield,recording 3.71×10^(18)sej/a for the RSR and 5.50×10^(18)sej/a for the RF;(c)the emergy sustainability index values of 1.98 for the RSR and 5.16 for the RF suggest robust sustainability potential,particularly for the RF,even amid intense environmental stresses.These results affirm the success of the innovative restoration strategies employed for riparian reconstruction in the URYR's mountainous urban settings,offering valuable insights and reference for future restorative decisions in response to complex hydrological regimes and topography of urban riparian zones,both within the URYR and elsewhere.展开更多
Riparian land use/land cover(LULC)plays a crucial role in maintaining riverine water quality by altering the transport of pollutants and nutrients.Nevertheless,establishing a direct relationship between water quality ...Riparian land use/land cover(LULC)plays a crucial role in maintaining riverine water quality by altering the transport of pollutants and nutrients.Nevertheless,establishing a direct relationship between water quality and LULC is challenging due to the multi-indicator nature of both factors.Water quality encompasses a multitude of physical,chemical,and biological parameters,while LULC represents a diverse array of land use types.Riparian habitat quality(RHQ)serves as an indicator of LULC.Yet,it remains to be seen whether RHQ can act as a proxy of LULC for assessing the impact of LULC on riverine water quality.This study examines the interplay between RHQ,LULC and water quality,and develops a comprehensive indicator to predict water quality.We measured several water quality parameters,including pH(potential of hydrogen),TN(total nitrogen),TP(total phosphorus),T_(water)(water temperature),DO(dissolved oxygen),and EC(electrical conductivity)of the Yue and Jinshui Rivers draining to the Han River during 2016,2017 and 2018.The water quality index(WQI)was further calculated.RHQ is assessed by the InVEST(Integrated Valuation of Ecosystem Services and Tradeoffs)model.Our study found noticeable seasonal differences in water quality,with a higher WQI observed in the dry season.The RHQ was strongly correlated with LULC compositions.RHQ positively correlated with WQI,and DO concentration and vegetation land were negatively correlated with T_(water),TN,TP,EC,cropland,and construction land.These correlations were stronger in the rainy season.Human-dominated land,such as construction land and cropland,significantly contributed to water quality degradation,whereas vegetation promoted water quality.Regression models showed that the RHQ explained variations in WQI better than LULC types.Our study concludes that RHQ is a new and comprehensive indicator for predicting the dynamics of riverine water quality.展开更多
The increasing demand for water and energy resources has led to widespread dam construction,particularly in ecologically sensitive regions like the Himalayan Range.This study focuses on the Uttarakhand state in the We...The increasing demand for water and energy resources has led to widespread dam construction,particularly in ecologically sensitive regions like the Himalayan Range.This study focuses on the Uttarakhand state in the Western Himalayas,where hydroelectric projects(HEPs)have significantly altered river flow regimes.The research investigates the impact of flow alterations on the composition and structure of riparian vegetation in the Garhwal Himalayas,specifically analysing four rivers regulated by hydroelectric projects.Utilizing the paired-reach comparison method,control(undisturbed),diverted(downstream of barrage/dam),and altered flow conditions(downstream of water outlet)were examined.The research reveals diverse and unique riparian ecosystems,with 89 genera and 113 taxa identified,showcasing the dominance of families like Asteraceae and Lamiaceae.The study unveils the structural importance of key species such as Berberis asiatica and Artemisia nilagirica.The density,diversity,and richness of shrub and herb species vary significantly across flow conditions.Notably,altered flow conditions demonstrate resilience in vegetation structure,while diverted conditions exhibit decreased species richness and density.The study emphasizes the importance of nuanced environmental flow management for mitigating adverse effects on riparian biodiversity in the fragile Himalayan region.These findings contribute to the global discourse on dam impacts and riparian ecology,shedding light on the complexities of this dynamic relationship in a vulnerable ecosystem.展开更多
Sixteen different vegetation types of grassland and shrubland were selected to study the component and diversity of plant species of riparian plant communities along main channel in the Three-Gorges areas. Species ric...Sixteen different vegetation types of grassland and shrubland were selected to study the component and diversity of plant species of riparian plant communities along main channel in the Three-Gorges areas. Species richness (s), Simpson index (D), and Shannon-Weiner index (H) were used to study the biodiversity and the hierarchical classification was carried out by the methods of TWINSPAN and DCA ordination. The results showed that the components of flora were complex and dominated by the temperate type in the riparian plant communities. Species diversity was not different between the communities, but Shannon-Weiner indexes of different layers in some grassland were significantly different. TWINSPAN and DCA indicated that riparian plant communities distributed along the gradient of moisture.展开更多
Due to the importance of riparian zone in maintaining and protecting regional biodiversity, increasingly more ecologists paid their attentions to riparian zone and had been aware of the important effects of riparian z...Due to the importance of riparian zone in maintaining and protecting regional biodiversity, increasingly more ecologists paid their attentions to riparian zone and had been aware of the important effects of riparian zone in basic study and practical management. In this study, 42 sampling belts (10 m?00 m) parallel to the bank of Xiangxi River at different elevations in Shennongjia Area were selected to investigate the riparian vegetation and rare plants. 14 species of rare plants were found distributing in riparian zone, accounting for 42.4% of the total rare plant species in Shennongjia Area. The main distribution range of the 14 rare plant species was the evergreen and deciduous mixed broadleaved forest at elevation of 1200-1800 m, where, species diversity of plant community was the maximum at the moderate elevation. The analysis of TWINSPAN divided the 14 rare species into 3 groups against the elevation, namely low elevation species group, moderate elevation species group, and high elevation species group. The analysis of DCA ordination showed similar results to that of TWINSPAN. In the paper, the authors discussed the reasons forming the distribution pattern of rare plant species, and pointed out that the important function of riparian zone on rare plant species protection.展开更多
This paper analyzed landscape status of the area where Majiagou Riparian Small Park in Harbin City-Wuxing Park was constructed, explained the park's design concept, overall structure layout, landscape and function...This paper analyzed landscape status of the area where Majiagou Riparian Small Park in Harbin City-Wuxing Park was constructed, explained the park's design concept, overall structure layout, landscape and function division, planting design, ecological planning and so on. The purpose of the design was to create for people an urban park with reasonable layout, distinct division, ecological function, historical memory and distinctive feature.展开更多
Riparian wetland is the major transition zone of matter, energy and information transfer between aquatic and terrestrial ecosystems and has important functions of water purification and non-point pollution control. Us...Riparian wetland is the major transition zone of matter, energy and information transfer between aquatic and terrestrial ecosystems and has important functions of water purification and non-point pollution control. Using the field experiment method and an isotope tracing technique, the agricultural non-point nitrogen pollution control function of different vegetation types in riparian wetland was studied in the Kouma Section of the Yellow River. The results showed that the retention of agricultural non-point nitrogen pollution by riparian wetland soil occurs mainly in top 0-10 cm layer. The amount of nitrogen retained by surface soils associated with three types of vegetation are 0.045 mg/g for Phragmites communis Trin Linn, 0.036 mg/g for Scirpus triqueter Linn, and 0.032 mg/g for Typha angustifolia Linn, which account for 59.21%, 56.25%, and 56.14% of the total nitrogen interception, respectively. Exogenous nitrogen in 0-10 cm soil layer changes more quickly than in other layers. One month after adding KISNO3 to the tested vegetation, nitrogen content was 77.78% for P communis Trin, 68.75% for T. angustifolia, and 8.33% for S. triqueter in the surface soil. After three months, nitrogen content was 93.33% for P. communis Trin, 72.22% for S. triqueter, and 37.50% for T. Angustifolia. There are large differences among vegetation communities respecting to purification of agricultural non-point nitrogen pollution. The nitrogen uptake amount decreases in the sequence： new shoots ofP. communis Trin （9.731 nag/g） 〉 old P. communis Trin （4.939 mg/g） 〉 S. triqueter （0.620 mg/g） 〉 T. angustifolia （0.186 mg/g）. Observations indicated that the presence of riparian wetlands as buffers on and adjacent to stream banks could be recommended to control agricultural non-point pollution.展开更多
Since 2000, the Chinese government has implemented emergency water diversion measures to restore the damaged riparian forest ecosystem with dominant tree species Euphrat poplar(Populus euphratica Oliv.)at the lower re...Since 2000, the Chinese government has implemented emergency water diversion measures to restore the damaged riparian forest ecosystem with dominant tree species Euphrat poplar(Populus euphratica Oliv.)at the lower reaches of the Tarim River. In the present study, comparative analysis of variations in the vitality of P. euphratica trees were made using 2005 and 2010 data to illustrate the revitalization process of riparian forest. Poplar trees within 300 m of the riverbed were positively revitalized, while the vitality of trees farther than 300 m from the river decreased. Population structure was studied to demonstrate the development of poplar community. In the first belt, the class structure for the diameter at breast height(DBH) of P. euphratica fit a logistic model, and the 2nd, 3rd and 4th belt curve fittings were close to a Gaussian model; in other plots they were bimodal. Cluster analysis of the composition of the DBH class of poplar trees demonstrated that those within 16–36 cm DBH were the most abundant(58.49% of total) in study area, under 16 cm of DBH were second(31.36%), and trees >40 cm DBH were the least abundant(10.15%). More than 80% of the trees were young and medium-sized, which means that the poplar forest community in the vicinity of the lower Tarim River is at a stable developmental stage. The abundance of juvenile trees of P. euphratica in the first and second measuring belts was 12.13% in 2005 and increased to 25.52% in 2010, which means that the emergency water transfer had a positive impact on the generation of young P. euphratica trees in the vicinity of the river.展开更多
We evaluated the distribution and accumulation of Cd, Cr, Cu, Ni, Pb and Zn in two plant species （Scirpus tripueter Linn. and Cyperus malaccensis Lam.）, in water and soils sampled from the reclaimed tidal riparian w...We evaluated the distribution and accumulation of Cd, Cr, Cu, Ni, Pb and Zn in two plant species （Scirpus tripueter Linn. and Cyperus malaccensis Lam.）, in water and soils sampled from the reclaimed tidal riparian wetlands （RTRWs） and the natural riparian wetlands （NRWs） in the Pearl River Estuary （PRE）. The results showed that the concentrations of studied heavy metals in soils exceeded the eco-toxic threshold recommended by US EPA. The concentrations of Cd, Cr and Zn in plants may lead to toxic effiects. The heavy metal concentrations were high in water and low in soils of RTRWs compared with that in the NRWs. The accumulation of heavy metals in the roots of plants was higher in NRWs than those in RTRWs while the opposite result was found for heavy metal accumulation in shoots. Based on the bioaccumulation and translocation factors, the plants in NRWs had a higher capacity to accumulate heavy metals while higher abilities to transport heavy metals from roots to shoots were observed in RTRWs. Heavy metal contaminations in RTRWs were dominated by anthropogenic sources from both side uplands and river water, whereas in NRWs, the metal accumulations were simultaneously affected by anthropogenic and natural factors展开更多
The migration of soil dissolved organic carbon(DOC) from terrestrial to aquatic environments has important impacts on the adjacent water quality and the transport of organic and inorganic contaminants.However,few stud...The migration of soil dissolved organic carbon(DOC) from terrestrial to aquatic environments has important impacts on the adjacent water quality and the transport of organic and inorganic contaminants.However,few studies have investigated the sources and properties of DOC in riparian zones.A total of 34 soil samples were collected across four riparian buffer zones(Zones A-D) on Chongming Island,China.The vertical distributions of soil organic carbon(SOC) and DOC,fluorescence excitation-emission matrix(EEM) spectra of DOC and the optical indices,including fluorescence index(FI),index of recent autochthonous contribution(BIX),and humification index(HIX),were measured across the riparian environment to investigate the sources and fluorescence properties of DOC.The results showed that SOC stored in the surface soil(0-30 cm) accounted for 40%of the total soil profile SOC.The DOC accumulated in Zones A-C,which accounted for 5%of the SOC.The fluorescence EEM spectra of DOC showed that DOC contained humic-like and protein-like substances,which were mainly derived from recent plant debris by microbes.A large amount of humic-like substances were sorbed to minerals in the surface soil(0-30 cm).In addition,the riparian topography and soil physico-chemical properties(pH,EC and moisture) dictated the transformation and transport of DOC.The results suggested that EEMs could reveal the source of DOC in riparian soil systems,and that optical indices were complementary tools that revealed the characteristics of soil DOC and provided supplemental evidence about DOC sources.展开更多
This field study investigated the nitrogen concentrations in the shallow groundwater from an ephemeral stream and four land uses： cropland, two-year restored （2yr） and five-years restored （Syr） woodlands, fishpon...This field study investigated the nitrogen concentrations in the shallow groundwater from an ephemeral stream and four land uses： cropland, two-year restored （2yr） and five-years restored （Syr） woodlands, fishponds, and the nitrogen flux in the riparian zone of Yuqiao Reservoir. The groundwater nitrate-N concentrations in cropland were the highest among the four land uses. Total dissolved nitrogen （TDN） and nitrate-N concentrations in the 2yr woodland were significantly （p 〈 0.05） higher than in 5yr woodland. The lowest nitrogen concentrations were detected in fishponds. Nitrate-N was the main form in cropland and 2yr woodland, whereas both nitrate-N and dissolved organic nitrogen （DON） were the main species in 5yr woodland and fishponds. But, ammonium-N was the main form in the ephemeral stream. During the rainy season, the groundwater flow with dissolved nitrogen drains from upland into the reservoir along the hydraulic gradient. The woodland between the cropland and reservoir could act as a buffer to retain shallow groundwater nitrogen. The dominant form of ammonium-N in the groundwater TDN pool in ephemeral stream indicated that nitrogen from the village and orchard in upland flowed into the reservoir via subsurface flow. The fishpond was not an important pollution source for nitrogen transfer via shallow groundwater.展开更多
Plants distributed in riparian regions experience frequent episodes of flooding and drought between years, and hence, riparian plants need to be flood- and drought-tolerant. Riparian plants possess various traits to s...Plants distributed in riparian regions experience frequent episodes of flooding and drought between years, and hence, riparian plants need to be flood- and drought-tolerant. Riparian plants possess various traits to survive flooding, while their sensitivity to drought has received less attention. To investigate the growth and photosynthetic responses of a riparian species （Bolboschoenus planiculmis） to flooding and drought, plants of this species were subjected to 60-d flooding or drought stress under greenhouse conditions. Growth and photosynthetic traits were measured at the end of the treatments. As well, we determined the efficiency of photosynthetic apparatus in mature leaves. Plants of B. planiculmis adequately adjusted their growth and photosynthetic traits under both flooding and drought conditions. Flooding did not affect the above-ground growth of B. planiculmis. Increased growth of roots and rhizomes and the generation of new tubers suggested a high ability of below-ground lateral growth by capturing resources under flooding conditions. Enhanced photosynthetic capacity, retained leaf pigment concentrations and chlorophyll a fluorescence capacity indicated photosynthetic adaptation to flooding. In contrast, drought significantly decreased the above-ground growth of B. planiculmis, especially the leaves, thereby minimizing water loss due to transpiration. Its increased root to shoot ratio and ＂phalanx＂ asexual propagation pattern might enhance soil water uptake ability. Although the functional leaves of B. planiculmis could retain their leaf pigment concentrations, as well as photosynthesis and chlorophyll a fluorescence, the total biomass of plants decreased, which may be a consequence of the reduced leaf area, suggesting adverse effects by drought. Therefore, both growth and photosynthetic responses of B. planiculmis are likely to contribute to the ability of this species to thrive in riparian regions, but remain susceptive to drought.展开更多
Rapid population growth and artificial oasis enlargement did pose great threat to the natural riparian ecosystems of Tarim River and caused seriously ecological deterioration and greater desertification of the Tarim R...Rapid population growth and artificial oasis enlargement did pose great threat to the natural riparian ecosystems of Tarim River and caused seriously ecological deterioration and greater desertification of the Tarim River Basin in the second half of 20 century. Restoration of the endangered riparian ecosystem requires that environmental flow should be restored through restricted and uncontrolled flow diversion irrigation in tributary areas. Implementation of such restriction needs further the basin-wide reallocation of water resources through a set of engineering and non-engineering measures taken to ensure the water requirement in the tributary and maintain effective flows in Tarim River. As one of evolving HELP (Hydrology for Environment, Life and Policy) basins, the article first presents an overview of hydrology, socio-economic development and ecosystem evolution of the Tarim River Basin. Then, those measures for restoring and maintaining environmental flow are reviewed and analyzed along with its applicability and validity. The issues emerging in implementing those measures are also explored, and then the conclusions were summarized. Lessons learned could provide a good example for other basins under similar conditions.展开更多
Many factors can affect the sediment deposition and soil erosion process in riparian zone, including terrain, sediment transport and water level fluctuations. Clarifying the factors influencing sediment deposition pro...Many factors can affect the sediment deposition and soil erosion process in riparian zone, including terrain, sediment transport and water level fluctuations. Clarifying the factors influencing sediment deposition process in the riparian zone of the Three Gorges Reservoirs is an important problem to determine the key area of sediment deposition and its trend of development in the study area. In order to reveal the influence of these environmental factors on the sediment deposition in riparian zone of the Three Gorges Reservoir, this study investigated 1） the amount of deposited sediment in different environmental conditions, 2） the potential factors affecting sediment deposition in riparian zone of the Three Gorges Reservoir, 3） the relationship between the deposited sediment amount and these factors previously mentioned using correlation analysis, and 4） the influence of human activities considered as an additional factor. This study found that 1） slope gradient, elevation, inundating duration and human activities were the main factors influencing sedimentation in riparian zone of the Three Gorges Reservoir, and 2） the impact of each factor varied with spaces. Specifically, in the upper reach from Jiangjin to Fuling, human activities such as gravel dredging, bank revetment and ports and wharfs constructing disturbed considerable amounts of deposited sediment, as a result, there was no natural law to dictate the distribution. In the middle reach from Fuling to Fengjie, slope gradient and inundating duration were the controlling factors, and the sediment deposition amount was greater in the areas with a gentler slope or lower elevation. Water flow on gentler slopes generally had lower velocity, resulting in more sediment to deposit. Sites with lower elevations would be drowned by sediment-laden flow with a longer duration resulting from hydrologic regime controlled by the operating strategy of the Three Gorges Reservoir, leading to a larger amount of sediment deposition. In the lower reach from Fengjie to Zigni, slope gradient was similar to the middle reach, performing a primary factor, while other factors showed little relationship with sediment amount.展开更多
A pot experiment was conducted to investigate the biodegradation dynamics and related microbial ecophysiological responses to butachlor addition in a riparian soil planted with different plants such as Phragmites aust...A pot experiment was conducted to investigate the biodegradation dynamics and related microbial ecophysiological responses to butachlor addition in a riparian soil planted with different plants such as Phragmites australis,Zizania aquatica,and Acorus calamus.The results showed that there were significant differences in microbial degradation dynamics of butachlor in the rhizosphere soils among the three riparian plants.A.calamus displays a significantly higher degradation efficiency of butachlor in the rhizosphere soils,as compared with Z.aquatica and P.australis.Half-life time of butachlor degradation in the rhizospheric soils of P.australis,Z.aquatica,and A.calamus were 7.5,9.8 and 5.4 days,respectively.Residual butachlor concentration in A.calamus rhizosphere soil was 35.2% and 21.7% lower than that in Z.aquatica and P.australis rhizosphere soils,respectively,indicating that A.calamus showed a greater improvement effect on biodegradation of butachlor in rhizosphere soils than the other two riparian plant.In general,microbial biomass and biochemical activities in rhizosphere soils were depressed by butachlor addition,despite the riparian plant types.However,rhizospheric soil microbial ecophysiological responses to butachlor addition significantly （P 0.05） differed between riparian plant species.Compared to Z.aquatica and P.australis,A.calamus showed significantly larger microbial number,higher enzyme activities and soil respiration rates in the rhizosphere soils.The results indicated that A.calamus have a better alleviative effect on inhibition of microbial growth due to butachlor addition and can be used as a suitable riparian plant for detoxifying and remediating butachlor contamination from agricultural nonpoint pollution.展开更多
The dynamic environments in riparian zones support a variety of life-history strategies, which constitute a fundamental mechanism for development and maintenance of biodiversity in riparian forest ecosystems. To demon...The dynamic environments in riparian zones support a variety of life-history strategies, which constitute a fundamental mechanism for development and maintenance of biodiversity in riparian forest ecosystems. To demonstrate the effect of life-history strategies on biodiversity, we investigated community-level diversity and its relationship to environmental variability in the riparian Populus euphratica forests of the Ejina Oasis. Communities were divided into 14 associations on the basis of their species impor- tance values. The Simpson＇s index, Shannon-Wiener index, Pielou＇s evenness index and the regional Whittaker＇s index were applied to calculate community diversity. An ordination of the sample plots was carried out by correspondence analysis （CA）. Biodiversity was relatively low across the entire study area, but there was high community diversity （flw = 8.09） due to the spatial heterogeneity of habitats in different plots. In addition, we investigated the relationship between biodiversity and several environmental factors, such as water availability, community components and soil conditions. We conclude that the heterogeneity of soil and water availability drives community diversity patterns in riparian zones and that community-level diversity favors the maintenance of species diversity in the P euphratica forests in the Ejina Oasis.展开更多
Since the impoundment of the Three Gorges Reservoir(TGR), the riparian zone has been subjected to numerous environmental changes. This study was conducted to recognize the distribution of grass roots and its impacts o...Since the impoundment of the Three Gorges Reservoir(TGR), the riparian zone has been subjected to numerous environmental changes. This study was conducted to recognize the distribution of grass roots and its impacts on soil nutrients in the water level fluctuation zone of TGR. Roots of four predominant herbaceous plants in the study area, specifically, Cynodon dactylon, Hemarthria altissima, Hemarthria compressa, and Paspalum paspaloides, and their corresponding relation with soil nutrient contents were investigated. Root surface area density was determined with Win RHIZO, and the relationships of root distribution with soil depths and soil nutrient contents were studied. The results indicates that most roots are distributed in the top soil layer of 0-10 cm. Estimated root surface area density for the selected grass species ranges from 0.16 to 13.44 cm^2/cm^3, and decreases exponentially with an increase in soil depth. Soil organic matter and total nitrogen contents are significantly lower on bare control area than the corresponding values on the grasslands. Total nutrient contents on grasslands of C. dactylon and H. compressa are higher than those of other grass areas. Root length density and root surface area density are significantly correlated with soil organic matter and total nitrogen content for the four grasslands. The present results suggests that plant roots have significant effects on the distribution of soil nutrients in soil profiles in the riparian zone along the TGR. Nevertheless, additional investigations are needed to reveal the specific interactions between plant roots distribution, soil nutrients and water level fluctuations.展开更多
Nighttime sap flow is a potentially important factor that affects whole-plant water balance and water-use efficiency （WUE）. Its functions include predawn disequilibrium between plant and soil water potentials as wel...Nighttime sap flow is a potentially important factor that affects whole-plant water balance and water-use efficiency （WUE）. Its functions include predawn disequilibrium between plant and soil water potentials as well as between the increments of oxygen supply and nutrient uptake. However, main factors that drive nighttime sap flow remain unclear, and researches related to the relationship between nighttime sap flow velocity and environmental factors are limited. Accordingly, we investigated the variations in the nighttime sap flow of Populus euphratica in a desert riparian forest of an extremely arid region, Northwest China. Results indicated that P. euphratica sap flow occurred throughout the night during the growing season because of the partial stomata opening. Nighttime sap flow for the P. euphratica forest accounted for 31%-47% of its daily sap flow during the growing season. The high value of nighttime sap flow could be the result of high stomatal conductance and could have significant implications for water budgets. Throughout the whole growing season, nighttime sap flow velocity of P. euphratica was positively correlated with the vapor pressure deficit （VPD）, air temperature and soil water content. We found that VPD and soil water content were the main driving factors for nighttime sap flow of P. euphratica.展开更多
基金support of the National Biodiversity Future Center (NBFC) to the University of Padova,the Research Centre for Plant ProtectionCertification (CREA),and the National Research Council (CNR),funded under the National Recovery and Resilience Plan (NRRP)+2 种基金Mission 4 Component 2 Investment 1.4-Call for tender No.3138 of 16 December 2021,rectified by Decree n.3175 of 18 December 2021 of Italian Ministry of University and Research funded by the European Union–NextGenerationEUProject code CN_00000033,Concession Decree No.1034 of 17 June 2022adopted by the Italian Ministry of University and Research,CUP:C93C22002810006,CUP:B83D21014060006,CUP:B83C22002930006,Project title“National Biodiversity Future CenterNBFC”support by Beaver Trust,grant number:1185451
文摘The Eurasian beaver(Castor fiber Linnaeus,1758)can be considered a hydrological ecosystem engineer as it shapes environmental characteristics through its building activities and feeding behaviour.Even if several studies have so far reported beaver impact on multi-taxon biodiversity and forest regeneration,there is a lack of research on forest stand structure evolution following beaver direct activity on trees.This represents a pivotal topic for predicting restoration outcomes and reccommending sound silvicultural and management practices to maintain specific forest conditions.Specifically,the study aims at investigating forest stand structure and tree species diversity changes considering river variability,distance from the riverbank and beaver's gnawing activity intensity.The Eurasian beaver is only recently recolonising the three analysed Mediterranean rivers,but stand structure seems to be already significantly impacted by the species.The number of trees was reduced,increasing mean diameter at breast height at stand level,as most of the youngest and/or smaller trees are entirely cut down.Strongest structural variations can be detected in intensively impacted stands and in the forest portions closer to the riverbank.The absence of a significant effect on most of the diversity indices is likely due to the initially homogeneous composition of the tree layer in each stand and to the limited variety of beaver's diet within the sites.Future resprouting of secondary tree shoots,as well as beaver gnawing activity changes in intensity over time and space,can further produce variations in structural parameters and woody species diversity in the medium-and long-term period.Therefore,it will be crucial to further monitor the long-term effects,as structural shifts can produce significant effects on riparian ecosystem functions.
基金supported by the Third Xinjiang Scientific Expedition and Research Program of the Ministry of Science&Technology of China(Grant No:2022xjkk0300)National Science Foundation of China(Grant No:32260285)+1 种基金Graduate Research Innovation Project of the Xinjiang Uygur Autonomous Region(Grant No:XJ2024G049)Excellent Doctoral Innovation Program of Xinjiang University(Grant No:XJU2024BS121).
文摘The distance from the river is a crucial factor that affects the structure and function of desert riparian forests,impeding their regeneration and biodiversity due to water conditions.However,few studies have confirmed the long-term variation in structure and function of this azonal riparian forest type caused by water stress.We hypothesize that a complex and diverse stand structure is associated with the distance from the river,and tree size plays a crucial role in establishing random frameworks for stability in forest stands.Our investigation was conducted in the lower Trim River.Based on long-term observation from 2005 to 2023,both stand structure parameters and diversity index were used.The variation in stand structure was analyzed using the least significant difference,and stand stability was assessed using Gaussian distribution and bivariate regression methods.Our study indicated that there were no significant differences in the response of size differentiation and crowding to distance from the river.However,a significant divergence in spatial pattern was observed at greater distances from the river,which became more pronounced over time.Regardless of the distance from the river or time-scale,there were significant differences in DBH,crown diameter and length.Furthermore,structural diversity exhibited varying trends with distance from the river and time-scale,indicating a diverse and complex pattern in stand structure due to water stress.The proportion of random frameworks for stability is influenced by the distance from the river,and tree size,especially crown diameter and length,plays an important role.Our research examines the multiple relationships among water conditions,forest structure,and function in an arid region,highlighting the significance of water conditions in the natural restoration of desert riparian forest ecosystems.The findings provide new insights for further exploration of the relationship between stand structure and stability,enhancing our understanding of the theory of random frameworks-stability.Overall,the study provides scientific guidance for sustainable forest management and conservation in the context of a changing climate,particularly regarding water stress.
基金supported by the Young Scientists Fund of the National Natural Science Fund of China(grant numbers 51808065 and 31901152)the General Program of the National Natural Science Foundation of China(grant number 52178031)
文摘Complex hydrological regimes and rugged topography in mountainous cities have increasingly compromised urban riparian zones,presenting marked restoration challenges.This study conducted restoration trials along the Jiulongtan riparian zone,located in the upper reaches of the Yangtze River(URYR),China.It featured 2 major ecological engineering interventions:(a)establishing semi-natural meadows and applying braided branched meshes to the riparian slope revetment and(b)constructing littoral woods and managing microtopography and sediment in the floodplain area.Furthermore,emergy evaluation was utilized to gauge the effectiveness of these restoration strategies and to assess the sustainability of the reconstructed riparian ecosystems.The following results were obtained:(a)Both the restored slope revetment(RSR)and restored floodplain(RF)ecosystems achieved a state of performance equilibrium after their implementation,with the former benefiting from renewable energy investments and the latter effectively utilizing local resources;(b)service yield outcomes highlighted significant enhancements in species diversity within the reconstructed ecosystems;plant diversity emerged as the primary contributor to total service yield,recording 3.71×10^(18)sej/a for the RSR and 5.50×10^(18)sej/a for the RF;(c)the emergy sustainability index values of 1.98 for the RSR and 5.16 for the RF suggest robust sustainability potential,particularly for the RF,even amid intense environmental stresses.These results affirm the success of the innovative restoration strategies employed for riparian reconstruction in the URYR's mountainous urban settings,offering valuable insights and reference for future restorative decisions in response to complex hydrological regimes and topography of urban riparian zones,both within the URYR and elsewhere.
基金supported by the National Natural Science Foundation of China(Grant No.31670473)the Wuhan Institute of Technology funding to Dr.Siyue Li(Grant No.21QD02).
文摘Riparian land use/land cover(LULC)plays a crucial role in maintaining riverine water quality by altering the transport of pollutants and nutrients.Nevertheless,establishing a direct relationship between water quality and LULC is challenging due to the multi-indicator nature of both factors.Water quality encompasses a multitude of physical,chemical,and biological parameters,while LULC represents a diverse array of land use types.Riparian habitat quality(RHQ)serves as an indicator of LULC.Yet,it remains to be seen whether RHQ can act as a proxy of LULC for assessing the impact of LULC on riverine water quality.This study examines the interplay between RHQ,LULC and water quality,and develops a comprehensive indicator to predict water quality.We measured several water quality parameters,including pH(potential of hydrogen),TN(total nitrogen),TP(total phosphorus),T_(water)(water temperature),DO(dissolved oxygen),and EC(electrical conductivity)of the Yue and Jinshui Rivers draining to the Han River during 2016,2017 and 2018.The water quality index(WQI)was further calculated.RHQ is assessed by the InVEST(Integrated Valuation of Ecosystem Services and Tradeoffs)model.Our study found noticeable seasonal differences in water quality,with a higher WQI observed in the dry season.The RHQ was strongly correlated with LULC compositions.RHQ positively correlated with WQI,and DO concentration and vegetation land were negatively correlated with T_(water),TN,TP,EC,cropland,and construction land.These correlations were stronger in the rainy season.Human-dominated land,such as construction land and cropland,significantly contributed to water quality degradation,whereas vegetation promoted water quality.Regression models showed that the RHQ explained variations in WQI better than LULC types.Our study concludes that RHQ is a new and comprehensive indicator for predicting the dynamics of riverine water quality.
文摘The increasing demand for water and energy resources has led to widespread dam construction,particularly in ecologically sensitive regions like the Himalayan Range.This study focuses on the Uttarakhand state in the Western Himalayas,where hydroelectric projects(HEPs)have significantly altered river flow regimes.The research investigates the impact of flow alterations on the composition and structure of riparian vegetation in the Garhwal Himalayas,specifically analysing four rivers regulated by hydroelectric projects.Utilizing the paired-reach comparison method,control(undisturbed),diverted(downstream of barrage/dam),and altered flow conditions(downstream of water outlet)were examined.The research reveals diverse and unique riparian ecosystems,with 89 genera and 113 taxa identified,showcasing the dominance of families like Asteraceae and Lamiaceae.The study unveils the structural importance of key species such as Berberis asiatica and Artemisia nilagirica.The density,diversity,and richness of shrub and herb species vary significantly across flow conditions.Notably,altered flow conditions demonstrate resilience in vegetation structure,while diverted conditions exhibit decreased species richness and density.The study emphasizes the importance of nuanced environmental flow management for mitigating adverse effects on riparian biodiversity in the fragile Himalayan region.These findings contribute to the global discourse on dam impacts and riparian ecology,shedding light on the complexities of this dynamic relationship in a vulnerable ecosystem.
基金This study was supported by the Chinese Academy of Sciences (A grant KZCX2-406) the National Natural Science Foundation of China (NSFC39970123) and Changbai Mountain Open Research Station.
文摘Sixteen different vegetation types of grassland and shrubland were selected to study the component and diversity of plant species of riparian plant communities along main channel in the Three-Gorges areas. Species richness (s), Simpson index (D), and Shannon-Weiner index (H) were used to study the biodiversity and the hierarchical classification was carried out by the methods of TWINSPAN and DCA ordination. The results showed that the components of flora were complex and dominated by the temperate type in the riparian plant communities. Species diversity was not different between the communities, but Shannon-Weiner indexes of different layers in some grassland were significantly different. TWINSPAN and DCA indicated that riparian plant communities distributed along the gradient of moisture.
基金This project was supported by National Natural Science Foundation of China (NSFC39970123) Changbai Mountain Open Research Station, Chinese Acedamy of Science.
文摘Due to the importance of riparian zone in maintaining and protecting regional biodiversity, increasingly more ecologists paid their attentions to riparian zone and had been aware of the important effects of riparian zone in basic study and practical management. In this study, 42 sampling belts (10 m?00 m) parallel to the bank of Xiangxi River at different elevations in Shennongjia Area were selected to investigate the riparian vegetation and rare plants. 14 species of rare plants were found distributing in riparian zone, accounting for 42.4% of the total rare plant species in Shennongjia Area. The main distribution range of the 14 rare plant species was the evergreen and deciduous mixed broadleaved forest at elevation of 1200-1800 m, where, species diversity of plant community was the maximum at the moderate elevation. The analysis of TWINSPAN divided the 14 rare species into 3 groups against the elevation, namely low elevation species group, moderate elevation species group, and high elevation species group. The analysis of DCA ordination showed similar results to that of TWINSPAN. In the paper, the authors discussed the reasons forming the distribution pattern of rare plant species, and pointed out that the important function of riparian zone on rare plant species protection.
文摘This paper analyzed landscape status of the area where Majiagou Riparian Small Park in Harbin City-Wuxing Park was constructed, explained the park's design concept, overall structure layout, landscape and function division, planting design, ecological planning and so on. The purpose of the design was to create for people an urban park with reasonable layout, distinct division, ecological function, historical memory and distinctive feature.
基金supported by the National Natural Sci- ence Foundation of China (No. 30570276)
文摘Riparian wetland is the major transition zone of matter, energy and information transfer between aquatic and terrestrial ecosystems and has important functions of water purification and non-point pollution control. Using the field experiment method and an isotope tracing technique, the agricultural non-point nitrogen pollution control function of different vegetation types in riparian wetland was studied in the Kouma Section of the Yellow River. The results showed that the retention of agricultural non-point nitrogen pollution by riparian wetland soil occurs mainly in top 0-10 cm layer. The amount of nitrogen retained by surface soils associated with three types of vegetation are 0.045 mg/g for Phragmites communis Trin Linn, 0.036 mg/g for Scirpus triqueter Linn, and 0.032 mg/g for Typha angustifolia Linn, which account for 59.21%, 56.25%, and 56.14% of the total nitrogen interception, respectively. Exogenous nitrogen in 0-10 cm soil layer changes more quickly than in other layers. One month after adding KISNO3 to the tested vegetation, nitrogen content was 77.78% for P communis Trin, 68.75% for T. angustifolia, and 8.33% for S. triqueter in the surface soil. After three months, nitrogen content was 93.33% for P. communis Trin, 72.22% for S. triqueter, and 37.50% for T. Angustifolia. There are large differences among vegetation communities respecting to purification of agricultural non-point nitrogen pollution. The nitrogen uptake amount decreases in the sequence： new shoots ofP. communis Trin （9.731 nag/g） 〉 old P. communis Trin （4.939 mg/g） 〉 S. triqueter （0.620 mg/g） 〉 T. angustifolia （0.186 mg/g）. Observations indicated that the presence of riparian wetlands as buffers on and adjacent to stream banks could be recommended to control agricultural non-point pollution.
基金supported by National Natural Science Foundation of China(Grant Nos:31360200,31270742)the German Volkswagen Foundation within the framework of EcoCAR project(Az.:88497)
文摘Since 2000, the Chinese government has implemented emergency water diversion measures to restore the damaged riparian forest ecosystem with dominant tree species Euphrat poplar(Populus euphratica Oliv.)at the lower reaches of the Tarim River. In the present study, comparative analysis of variations in the vitality of P. euphratica trees were made using 2005 and 2010 data to illustrate the revitalization process of riparian forest. Poplar trees within 300 m of the riverbed were positively revitalized, while the vitality of trees farther than 300 m from the river decreased. Population structure was studied to demonstrate the development of poplar community. In the first belt, the class structure for the diameter at breast height(DBH) of P. euphratica fit a logistic model, and the 2nd, 3rd and 4th belt curve fittings were close to a Gaussian model; in other plots they were bimodal. Cluster analysis of the composition of the DBH class of poplar trees demonstrated that those within 16–36 cm DBH were the most abundant(58.49% of total) in study area, under 16 cm of DBH were second(31.36%), and trees >40 cm DBH were the least abundant(10.15%). More than 80% of the trees were young and medium-sized, which means that the poplar forest community in the vicinity of the lower Tarim River is at a stable developmental stage. The abundance of juvenile trees of P. euphratica in the first and second measuring belts was 12.13% in 2005 and increased to 25.52% in 2010, which means that the emergency water transfer had a positive impact on the generation of young P. euphratica trees in the vicinity of the river.
基金supported by the National Natural Science Foundation of China (No. U0833002 41071330)the Fundamental Research Funds for the Central Universities of China (No. 2009SD-24)
文摘We evaluated the distribution and accumulation of Cd, Cr, Cu, Ni, Pb and Zn in two plant species （Scirpus tripueter Linn. and Cyperus malaccensis Lam.）, in water and soils sampled from the reclaimed tidal riparian wetlands （RTRWs） and the natural riparian wetlands （NRWs） in the Pearl River Estuary （PRE）. The results showed that the concentrations of studied heavy metals in soils exceeded the eco-toxic threshold recommended by US EPA. The concentrations of Cd, Cr and Zn in plants may lead to toxic effiects. The heavy metal concentrations were high in water and low in soils of RTRWs compared with that in the NRWs. The accumulation of heavy metals in the roots of plants was higher in NRWs than those in RTRWs while the opposite result was found for heavy metal accumulation in shoots. Based on the bioaccumulation and translocation factors, the plants in NRWs had a higher capacity to accumulate heavy metals while higher abilities to transport heavy metals from roots to shoots were observed in RTRWs. Heavy metal contaminations in RTRWs were dominated by anthropogenic sources from both side uplands and river water, whereas in NRWs, the metal accumulations were simultaneously affected by anthropogenic and natural factors
基金supported by the Major Science and Technology Program for Water Pollution Control and Treatment of China(Nos.2011ZX07303-001 and 2014ZX07303-003)the State Key Laboratory of Soil and Sustainable Agriculture,Institute of Soil Science,Chinese Academy of Sciences(No.Y412201426)
文摘The migration of soil dissolved organic carbon(DOC) from terrestrial to aquatic environments has important impacts on the adjacent water quality and the transport of organic and inorganic contaminants.However,few studies have investigated the sources and properties of DOC in riparian zones.A total of 34 soil samples were collected across four riparian buffer zones(Zones A-D) on Chongming Island,China.The vertical distributions of soil organic carbon(SOC) and DOC,fluorescence excitation-emission matrix(EEM) spectra of DOC and the optical indices,including fluorescence index(FI),index of recent autochthonous contribution(BIX),and humification index(HIX),were measured across the riparian environment to investigate the sources and fluorescence properties of DOC.The results showed that SOC stored in the surface soil(0-30 cm) accounted for 40%of the total soil profile SOC.The DOC accumulated in Zones A-C,which accounted for 5%of the SOC.The fluorescence EEM spectra of DOC showed that DOC contained humic-like and protein-like substances,which were mainly derived from recent plant debris by microbes.A large amount of humic-like substances were sorbed to minerals in the surface soil(0-30 cm).In addition,the riparian topography and soil physico-chemical properties(pH,EC and moisture) dictated the transformation and transport of DOC.The results suggested that EEMs could reveal the source of DOC in riparian soil systems,and that optical indices were complementary tools that revealed the characteristics of soil DOC and provided supplemental evidence about DOC sources.
基金supported by the Key Project of Knowledge Innovation Programme of CAS(No.KZCX1-YW-06-02)the National Basic Research Priorities Program of China(No.2006CB403306)the National Natural Science Foundation of China(No.40601036).
文摘This field study investigated the nitrogen concentrations in the shallow groundwater from an ephemeral stream and four land uses： cropland, two-year restored （2yr） and five-years restored （Syr） woodlands, fishponds, and the nitrogen flux in the riparian zone of Yuqiao Reservoir. The groundwater nitrate-N concentrations in cropland were the highest among the four land uses. Total dissolved nitrogen （TDN） and nitrate-N concentrations in the 2yr woodland were significantly （p 〈 0.05） higher than in 5yr woodland. The lowest nitrogen concentrations were detected in fishponds. Nitrate-N was the main form in cropland and 2yr woodland, whereas both nitrate-N and dissolved organic nitrogen （DON） were the main species in 5yr woodland and fishponds. But, ammonium-N was the main form in the ephemeral stream. During the rainy season, the groundwater flow with dissolved nitrogen drains from upland into the reservoir along the hydraulic gradient. The woodland between the cropland and reservoir could act as a buffer to retain shallow groundwater nitrogen. The dominant form of ammonium-N in the groundwater TDN pool in ephemeral stream indicated that nitrogen from the village and orchard in upland flowed into the reservoir via subsurface flow. The fishpond was not an important pollution source for nitrogen transfer via shallow groundwater.
基金supported by the Forestry Commonwealth Project (Grant No. 201004078)the National Science Foundation of China (Grant No.31200314)
文摘Plants distributed in riparian regions experience frequent episodes of flooding and drought between years, and hence, riparian plants need to be flood- and drought-tolerant. Riparian plants possess various traits to survive flooding, while their sensitivity to drought has received less attention. To investigate the growth and photosynthetic responses of a riparian species （Bolboschoenus planiculmis） to flooding and drought, plants of this species were subjected to 60-d flooding or drought stress under greenhouse conditions. Growth and photosynthetic traits were measured at the end of the treatments. As well, we determined the efficiency of photosynthetic apparatus in mature leaves. Plants of B. planiculmis adequately adjusted their growth and photosynthetic traits under both flooding and drought conditions. Flooding did not affect the above-ground growth of B. planiculmis. Increased growth of roots and rhizomes and the generation of new tubers suggested a high ability of below-ground lateral growth by capturing resources under flooding conditions. Enhanced photosynthetic capacity, retained leaf pigment concentrations and chlorophyll a fluorescence capacity indicated photosynthetic adaptation to flooding. In contrast, drought significantly decreased the above-ground growth of B. planiculmis, especially the leaves, thereby minimizing water loss due to transpiration. Its increased root to shoot ratio and ＂phalanx＂ asexual propagation pattern might enhance soil water uptake ability. Although the functional leaves of B. planiculmis could retain their leaf pigment concentrations, as well as photosynthesis and chlorophyll a fluorescence, the total biomass of plants decreased, which may be a consequence of the reduced leaf area, suggesting adverse effects by drought. Therefore, both growth and photosynthetic responses of B. planiculmis are likely to contribute to the ability of this species to thrive in riparian regions, but remain susceptive to drought.
基金the support of the UNESCO HELP programthe support of K.C.Wong Education Foundation,Hong Kong
文摘Rapid population growth and artificial oasis enlargement did pose great threat to the natural riparian ecosystems of Tarim River and caused seriously ecological deterioration and greater desertification of the Tarim River Basin in the second half of 20 century. Restoration of the endangered riparian ecosystem requires that environmental flow should be restored through restricted and uncontrolled flow diversion irrigation in tributary areas. Implementation of such restriction needs further the basin-wide reallocation of water resources through a set of engineering and non-engineering measures taken to ensure the water requirement in the tributary and maintain effective flows in Tarim River. As one of evolving HELP (Hydrology for Environment, Life and Policy) basins, the article first presents an overview of hydrology, socio-economic development and ecosystem evolution of the Tarim River Basin. Then, those measures for restoring and maintaining environmental flow are reviewed and analyzed along with its applicability and validity. The issues emerging in implementing those measures are also explored, and then the conclusions were summarized. Lessons learned could provide a good example for other basins under similar conditions.
基金funded by the Chinese Academy of Sciences(Grant Nos.KFJ-EW-STS-008,KFJSW-STS-175)
文摘Many factors can affect the sediment deposition and soil erosion process in riparian zone, including terrain, sediment transport and water level fluctuations. Clarifying the factors influencing sediment deposition process in the riparian zone of the Three Gorges Reservoirs is an important problem to determine the key area of sediment deposition and its trend of development in the study area. In order to reveal the influence of these environmental factors on the sediment deposition in riparian zone of the Three Gorges Reservoir, this study investigated 1） the amount of deposited sediment in different environmental conditions, 2） the potential factors affecting sediment deposition in riparian zone of the Three Gorges Reservoir, 3） the relationship between the deposited sediment amount and these factors previously mentioned using correlation analysis, and 4） the influence of human activities considered as an additional factor. This study found that 1） slope gradient, elevation, inundating duration and human activities were the main factors influencing sedimentation in riparian zone of the Three Gorges Reservoir, and 2） the impact of each factor varied with spaces. Specifically, in the upper reach from Jiangjin to Fuling, human activities such as gravel dredging, bank revetment and ports and wharfs constructing disturbed considerable amounts of deposited sediment, as a result, there was no natural law to dictate the distribution. In the middle reach from Fuling to Fengjie, slope gradient and inundating duration were the controlling factors, and the sediment deposition amount was greater in the areas with a gentler slope or lower elevation. Water flow on gentler slopes generally had lower velocity, resulting in more sediment to deposit. Sites with lower elevations would be drowned by sediment-laden flow with a longer duration resulting from hydrologic regime controlled by the operating strategy of the Three Gorges Reservoir, leading to a larger amount of sediment deposition. In the lower reach from Fengjie to Zigni, slope gradient was similar to the middle reach, performing a primary factor, while other factors showed little relationship with sediment amount.
基金supported by the Foundation of the State Key Laboratory of Pollution Control and Resource Reuse of China (No.PCRY09005)the National Special Item on Water Resource and Environment (No.2008ZX07316-4)the Key Project in the National Science & Technology Pillar Program (No.2009BAC62B00)
文摘A pot experiment was conducted to investigate the biodegradation dynamics and related microbial ecophysiological responses to butachlor addition in a riparian soil planted with different plants such as Phragmites australis,Zizania aquatica,and Acorus calamus.The results showed that there were significant differences in microbial degradation dynamics of butachlor in the rhizosphere soils among the three riparian plants.A.calamus displays a significantly higher degradation efficiency of butachlor in the rhizosphere soils,as compared with Z.aquatica and P.australis.Half-life time of butachlor degradation in the rhizospheric soils of P.australis,Z.aquatica,and A.calamus were 7.5,9.8 and 5.4 days,respectively.Residual butachlor concentration in A.calamus rhizosphere soil was 35.2% and 21.7% lower than that in Z.aquatica and P.australis rhizosphere soils,respectively,indicating that A.calamus showed a greater improvement effect on biodegradation of butachlor in rhizosphere soils than the other two riparian plant.In general,microbial biomass and biochemical activities in rhizosphere soils were depressed by butachlor addition,despite the riparian plant types.However,rhizospheric soil microbial ecophysiological responses to butachlor addition significantly （P 0.05） differed between riparian plant species.Compared to Z.aquatica and P.australis,A.calamus showed significantly larger microbial number,higher enzyme activities and soil respiration rates in the rhizosphere soils.The results indicated that A.calamus have a better alleviative effect on inhibition of microbial growth due to butachlor addition and can be used as a suitable riparian plant for detoxifying and remediating butachlor contamination from agricultural nonpoint pollution.
基金supported by the National Natural Science Foundation of China (No. 30570332)the 11th Five-Year Plan of the National Scientific and Technological Support Projects (2008BADB0B05)
文摘The dynamic environments in riparian zones support a variety of life-history strategies, which constitute a fundamental mechanism for development and maintenance of biodiversity in riparian forest ecosystems. To demonstrate the effect of life-history strategies on biodiversity, we investigated community-level diversity and its relationship to environmental variability in the riparian Populus euphratica forests of the Ejina Oasis. Communities were divided into 14 associations on the basis of their species impor- tance values. The Simpson＇s index, Shannon-Wiener index, Pielou＇s evenness index and the regional Whittaker＇s index were applied to calculate community diversity. An ordination of the sample plots was carried out by correspondence analysis （CA）. Biodiversity was relatively low across the entire study area, but there was high community diversity （flw = 8.09） due to the spatial heterogeneity of habitats in different plots. In addition, we investigated the relationship between biodiversity and several environmental factors, such as water availability, community components and soil conditions. We conclude that the heterogeneity of soil and water availability drives community diversity patterns in riparian zones and that community-level diversity favors the maintenance of species diversity in the P euphratica forests in the Ejina Oasis.
基金the National Natural Science Foundation of China (Grant Nos.41601296,41571278 and 41771321)China Postdoctoral Science Foundation (Grant No.2016M592720)+1 种基金Applied Basic Research Foundation of Yunnan Province (Grant No.2016FD011)Sichuan Science and Technology Program (2018SZ0132)
文摘Since the impoundment of the Three Gorges Reservoir(TGR), the riparian zone has been subjected to numerous environmental changes. This study was conducted to recognize the distribution of grass roots and its impacts on soil nutrients in the water level fluctuation zone of TGR. Roots of four predominant herbaceous plants in the study area, specifically, Cynodon dactylon, Hemarthria altissima, Hemarthria compressa, and Paspalum paspaloides, and their corresponding relation with soil nutrient contents were investigated. Root surface area density was determined with Win RHIZO, and the relationships of root distribution with soil depths and soil nutrient contents were studied. The results indicates that most roots are distributed in the top soil layer of 0-10 cm. Estimated root surface area density for the selected grass species ranges from 0.16 to 13.44 cm^2/cm^3, and decreases exponentially with an increase in soil depth. Soil organic matter and total nitrogen contents are significantly lower on bare control area than the corresponding values on the grasslands. Total nutrient contents on grasslands of C. dactylon and H. compressa are higher than those of other grass areas. Root length density and root surface area density are significantly correlated with soil organic matter and total nitrogen content for the four grasslands. The present results suggests that plant roots have significant effects on the distribution of soil nutrients in soil profiles in the riparian zone along the TGR. Nevertheless, additional investigations are needed to reveal the specific interactions between plant roots distribution, soil nutrients and water level fluctuations.
基金supported by the Major Research Plan of the National Natural Science Foundation of China (91025024)the Key Project of the Chinese Academy of Sciences (KZZD-EW-04-05)the West Light Foundation of the Chinese Academy of Sciences
文摘Nighttime sap flow is a potentially important factor that affects whole-plant water balance and water-use efficiency （WUE）. Its functions include predawn disequilibrium between plant and soil water potentials as well as between the increments of oxygen supply and nutrient uptake. However, main factors that drive nighttime sap flow remain unclear, and researches related to the relationship between nighttime sap flow velocity and environmental factors are limited. Accordingly, we investigated the variations in the nighttime sap flow of Populus euphratica in a desert riparian forest of an extremely arid region, Northwest China. Results indicated that P. euphratica sap flow occurred throughout the night during the growing season because of the partial stomata opening. Nighttime sap flow for the P. euphratica forest accounted for 31%-47% of its daily sap flow during the growing season. The high value of nighttime sap flow could be the result of high stomatal conductance and could have significant implications for water budgets. Throughout the whole growing season, nighttime sap flow velocity of P. euphratica was positively correlated with the vapor pressure deficit （VPD）, air temperature and soil water content. We found that VPD and soil water content were the main driving factors for nighttime sap flow of P. euphratica.
