Abstract
Riparian plant diversity in arid regions is sensitive to changes in groundwater. Although it is well known that groundwater has a significant influence on plant diversity, there have been few studies on how groundwater and soil salinity impact plant community in desert riparian ecosystems. Therefore, we surveyed 77 quadrats (100 m × 100 m) to examine the relationship between groundwater depth, groundwater salinity, soil salinity and plant community in the upper reaches of the Tarim River. Data were analyzed with two-way indicator species analysis (TWINSPAN), detrended canonical correspondence analysis (DCCA) and principal component analysis (PCA). The results indicated that Populus euphratica, Tamarix ramosissima, and Phragmites australis were the dominant plants among trees, shrubs and herbs, respectively. Five plant community types were classified. There were significant differences in species diversity, soil moisture, soil salinity, groundwater depth and groundwater salinity across the community types. The composition and distribution of plant community are significantly influenced by groundwater depth, groundwater salinity, soil moisture, distances from the river to the quadrats, soil pH, electrical conductivity, total salt, CO32−, Cl−, SO42−, Ca2+, Mg2+, Na+ and K+. Shallow groundwater depth, low groundwater salinity, and high soil moisture and soil salinity were associated with higher plant diversity.
Similar content being viewed by others
Introduction
Riparian areas are in the transition zone between aquatic and terrestrial ecosystems and play a significant role in the energy and nutrient fluxes between the two types of ecosystems1. Riparian habitats comprise a diverse collection of valuable species and are regarded as biodiversity corridors2. Riparian vegetation plays an important role in protecting biodiversity, providing animal food and habitats for animals, and maintaining ecological balance3. However, riparian vegetation has become less stable as groundwater tables have dropped, leading to declines in arid desert river systems4. Therefore, the analysis of the changes in species composition and community distribution is crucial for protecting the biodiversity of riparian ecosystems5.
Riparian vegetation in arid regions is mainly controlled by precipitation, surface runoff, and groundwater6. High rates of evapotranspiration and low annual precipitation are characteristic of arid desert river basins6. The low precipitation and limited surface runoff, both spatially and temporally, in extremely arid regions do not provide any significant source of water for plant growth7. Thus, groundwater constitutes the main water source for vegetation in arid river ecosystems8.
Riparian plant species, as groundwater-dependent vegetation, are referred to as phreatophytes9. Riparian vegetation productivity, biomass, competitiveness, composition, structure, and abundance are controlled by the groundwater10. Increases in water table depth has imposed drought stress on vegetation and reduced plant cover, diversity and richness11,12. Salt accumulation associated with high rate of evaporation of shallow groundwater through the unsaturated zone has been shown to influence plant composition in many arid riparian systems13. The area proximity to river had high salt accumulation12. The soil moisture content, electrical conductivity and pH in the areas nearer to the riverbank were generally higher than other areas14. Riparian plant species richness was positively associated with high soil pH in a riparian forest14,15. Therefore, it is necessary to understand the relationship between groundwater, soil salinity and the plant community in arid riparian ecosystems.
The Tarim River, located in the Tarim Basin, which is the most arid basin in China, is 1321 km long and is the second largest sandy desert on earth6,12. For the period from 1957 to 2000, the average annual inflow along the upper and lower reaches was 4.74 km3/a and 1.42 km3/a, respectively, while the environmental flow was 1.65 km3/a and 0.18 km3/a16, respectively. However, due to the severe misuse of water resources, the annual run-off in the upper reaches of the Tarim River has declined17, causing a reduction in the groundwater level in the upper and lower reaches18. The forests along the lower reaches have already been strongly degraded or even completely destroyed19. To restore and reconstruct the natural degraded arid riparian ecosystems, a 1.8 billion US dollar water diversion project has been invested in by the Chinese government since 2000. The restoration effort has been successful within 800 m from the river channel20. The groundwater depth declined from 12.6 m to 5.5–6.2 m between 2000 and 2015 in the lower reaches21. The riparian ecosystem plays a significant role instabilizing the water balance of the desert oasis and limiting desertification22,23. Many studies have examined the relationship between community and groundwater depth in the lower reaches of the Tarim River6,11,18. For example, Hao et al.6 found that richness and diversity declined with increasing groundwater depth. Li et al.24 found that the community structure changed from trees/shrubs/herbs to trees/shrubs when the groundwater depth increased from shallow to deep. Although it is well known that groundwater has a significant influence on plant diversity, there have been few studies on how groundwater and soil salinity impact the plant community in desert riparian ecosystems. Furthermore, the upper reaches, constituting the core area of the Tarim River riparian zone, are less well studied25.
The objectives of the present study are (1) to characterize the plant composition and community along the upper reaches of the Tarim River and (2) to determine the influences of groundwater depth and soil salinity on the plant communities. Our study provides a scientific foundation for informing government decisions related to ecological protection in arid riparian regions.
Results
Plant community composition
The plant composition categories in the upper reaches of the Tarim River included trees, shrubs, and herbs (Table 1). Twenty-two species were found in the 77 investigated quadrats: 2 tree species, 7 shrub species, and 13 herbaceous species. In the tree layer, the relative density, relative frequency, and relative dominance of P. euphratica were larger than those of P. pruinosa, and the importance value of P. euphratica was 80.31%. In the shrub and herbaceous layers, T. ramosissima and P. australis possessed the largest importance values (65.71% and 26.67%, respectively).
Classification of the plant communities
Five plant community classes were identified using TWINSPAN (Figs. 1b and 2; Fig. A1). Class 1: P. euphratica + Tamarix spp., L. ruthenicum, H. caspica, H. halodendron + A. sparsifolia, K. caspia, H. strobilaceum, C. sibiricum, P. hendersonii, I. salsoloides, and H. polydichotoma. P. euphratica (tree layer), Tamarix spp., L. ruthenicum, H. caspica, H. halodendron (shrub layer) and the herbaceous layer constitute the plant community (Table 2). Class 1 includes eight subclasses, with 17 plant quadrats that were mainly distributed in the direction of the oasis, close to the river channel (Fig. 1b).
Class 2: Populus spp.+ Tamarix spp.+ A. sparsifolia, H. polydichotoma, K. caspia, C. pseudophragmites, P. hendersonii, and P. australis. P. euphratica and P. pruinosa (tree layer), Tamarix spp. (shrub layer) and the herbaceous layer constitute the plant community (Table 2). Class 2 includes seven subclasses, with 29 plant quadrats that were mainly distributed in the direction of the desert, close to the river channel (Fig. 1b).
Class 3: Populus spp. + T. ramosissima + A. sparsifolia, G. inflata, and A. venetum. Populusspp. (tree layer), T. ramosissima (shrub layer), and few herbaceous plants constitute the plant community (Table 2). Class 3 includes 10 subclasses, with 17 plant quadrats that were mainly distributed an average distance of approximately 5 km away from the river channel (Fig. 1b).
Class 4: Tamarix spp., H. ammodendron + H. arachnoideus, and S. ruthenica. This plant community comprises Tamarix spp., H. ammodendron (shrub layer) and few herbaceous plants (Table 2). Class 4 includes six subclasses, with 10 plant quadrats that were mainly distributed an average distance of approximately 23 km away from the river channel (Fig. 1b).
Class 5: P. euphratica + H. arachnoideus, and S. ruthenica. This plant community comprises P. euphratica (tree layer) and few herbaceous plants (Table 2). Class 5 includes four subclasses, with four plant quadrats that were mainly distributed an average distance of approximately 22 km away from the river channel (Fig. 1b).
Plant diversity and environmental factors under different plant community types
Significant differences in the Shannon-Weiner index, Simpson index, evenness index, richness index, groundwater depth, distance from the river channel, soil pH, electrical conductivity, total salt, CO32−, Cl−, and SO42− were found among the five plant community types (Fig. 3; Table 3). The values of the plant diversity indices, groundwater and soil salinity for each community were ranked from the highest to the lowest values. The plant diversity indices, soil moisture, pH, EC, TS, CO32−, Cl−, and SO42− were ranked as follows: class 1, class 2, class 3, class 4, and class 5; distance from the river channel and groundwater depth: class 4, class 5, class 3, class 2, and class 1; groundwater salinity: class 5, class 4, class 3, class 2, and class 1.
DCCA analysis of the plant community and environmental factors
The results of the DCCA are displayed in ordination diagrams, with 77 quadrats or 22 species (Fig. 4). The triangles represent the species, and the vectors represent the 15 environmental parameters. The eigenvalues of the first two ordinations were 0.935 and 0.832. The first DCCA represents a gradient with increasing groundwater depth, distance from the river channel to the quadrat, and groundwater salinity, while soil moisture declines from left to right. The corresponding plant communities shift from classes 1 and 2 to classes 5 and 4. This suggests that plant community changes from high water consumers to drought-tolerant species. The community structure shifts from a tree-shrub-herb structure to a tree-herb or shrub-herb structure. The dominant plant species changed from P. euphratica, T. ramosissima and L. ruthenicum to P. euphratica or T. hispida as the distance from the river channel increased (Fig. 4a; A1). The composition of the herbaceous species changed from P. australis, K. caspia, H. strobilaceum and C. pseudophragmites to S. ruthenica and H. arachnoideus.
The second DCCA represents a gradient within declining soil salt (pH, EC, TS, CO32−, Cl−, SO42−, Ca2+, Mg2+, Na+, and K+), while groundwater salinity increases from top to bottom. The plant communities changed from classes 2 and 1 to class 3. The community structure changed from a tree-shrub-herb structure to a tree-shrub structure. The dominant species of the plant communities showed almost no change, but the soil salinity and groundwater salinity affected the herbaceous layer. There were few herbaceous plants, such as A. venetum and G. inflata, in class 3.
PCA of the environmental factors in the different plant communities
Groundwater depth, groundwater salinity, soil moisture and soil salinity in the five plant communities were assessed using PCA (Tables 4 and 5). Five principal components (g1, g2, g3, g4, and g5) were extracted with eigenvalues > 1.0, and their cumulative contribution rate reached 95.95%. The orders of the comprehensive appraisal value scores of the environmental factors were as follows: class 1 > class 2 > class 3 > class 4 > class 5 (Table 5), which is consistent with the plant diversity index result (Fig. 3).
Discussion
The Tarim River is China’s largest river and is the world’s fifth largest endorheic river20. In the present study, 22 plant species were found in the upper reaches of the Tarim River, which is higher than the number of species recorded in the lower reaches33. The plant species richness in the Tarim River is similar to that in the Syr Darya and Amu Darya Rivers34,35 but is low compared to that in the Gurbantünggüt Desert of the Junggar Basin in China36. In this study, the plant importance value analysis showed that P. euphratica and T. ramosissima were the most significant species in the tree and shrub layers, respectively (Table 1). This suggests that P. euphratica and T. ramosissima are dominant species in the upper reaches of the Tarim River, which corroborates the study of Hao et al.33 in the lower reaches of the Tarim River. It is possible that P. euphratica and T. ramosissima utilize a “sit-and-wait” strategy to avoid the disturbances from river runoff, resulting in them being the dominant species in the riparian plant communities of the upper and lower reaches37.
In the riparian forests of the upper reaches of the Tarim River, 2 trees, 7 shrubs and 13 herbaceous species were found during the survey. TWINSPAN successfully distinguished the riparian forests into five classes, which is greater than that recorded in the lower reaches of the Tarim River38. A partial overlap in species composition among the five classes was identified, indicating that some species exhibit broad environmental tolerance. For example, the keystone species P. euphratica and Tamarix spp. can exist from the riverside to the oasis and desert margins9,12. It is possible that P. euphratica and Tamarix spp. are flood-tolerant species37,39,40 and that they have evolved a unique allocation strategy that allows them to withstand flooding. For example, they often lose part of their aboveground biomass during flooding and increase the allocation of biomass to their roots during favorable times41. This supports the storage effect theory that carbohydrates stored in belowground tissue during favorable times allow the plants to survive flooding. Additionally, P. euphratica and Tamarix spp. are drought-tolerant species, and P. euphratica was found to growing in locations with a groundwater depth of up to 13 m (Table 3), which was in agreement with the finding of Gries et al.42 and Thomas et al.43. Tamarix spp. were found growing in locations with a groundwater depth of more than 14 m and had a greater ability than that of the other species to extract water from a relatively dry soil5, which was in agreement with the results presented by Gries et al.42.
Water availability plays an important role in the composition and distribution of plant communities, particularly in arid and semi-arid regions43. The DCCA indicated that the plant communities changed from classes 1and 2 to classes 5 and 4, transitioning from a tree-shrub dominated communities to a tree or shrub dominated communities as the water conditions changed from good to poor. The herbaceous species changed from P. australis, K. caspia, H. strobilaceum and C. pseudophragmites to S. ruthenica and H. arachnoideus as the distance from the river channel increased. This may be because herbaceous plants with shallow root systems are eliminated when the groundwater depth is too deep45,46. However, the herbaceous species S. ruthenica and H. arachnoideus can grow in desert habitats. These two herbaceous species exist under the dominant species P. euphratica and Tamarix spp., which have a significant “fertility island” effect44. For example, the plants trap nutrient rich sediments transported during floods, provide a sheltered microhabitat and reduce the surface temperature of the soil in the summer47. Therefore, P. euphratica and Tamarix spp.were the “nurse plants” for these two herbs.
In this study, the dominant species showed almost no change when the plant communities changed from classes 1 and 2 to class 3 as the soil salinity changed from high to low. This may be because the dominant species, P. euphratica and T. ramosissima, have deep roots and are able to access the less saline, shallow groundwater. However, soil salinity affected the herbaceous layer. This may be because the herbaceous plants may be more affected by changes in surface soil salinity because their roots are unable to access the less saline groundwater. There were few herbaceous plants, such as A. venetum and G. inflata, in class 3. A. venetum not only grows in class 3 but is also found in classes 1 and 2. This result indicated that A. venetum is distributed widely across the study area. Therefore, the different soil salinity requirements (i.e., niche differences) of the herbaceous plant reflect the soil salinity can determine the distributions of the herbaceous plants.
Environmental variability is considered to have an important influence on species diversity due to its effects on plant growth, development, and regeneration37,45,48. In this study, we analyzed the environmental characteristics of different plant communities using principal component analysis (PCA). The comprehensive appraisal value scores of the environmental factors of the five communities were ranked as follows: class 1 > class 2 > class 3 > class 4 > class 5. Plant diversity may change in response to environmental gradients49. The quadrats in classes 1 and 2 were mainly distributed close to the river; this area is associated with shallow groundwater depth, low groundwater salinity, and high soil moisture and soil salinity. These environmental factors have positive effects on species diversity14,20,21,49. It is also possible that the quadrats close to the river experienced flooding disturbances, and as plant diversity is highest at moderate flooding stress, this supports the intermediate disturbance hypothesis2,50. The quadrats in classes 4 and 5 were mainly distributed at the edge of the desert; this area is characterized by a deep groundwater depth, high groundwater salinity, and low soil moisture. These environmental factors have negative effects on species diversity10,38,43. The seedlings of the dominant species, P. euphratica and Tamarix spp., were mainly established in a moist environment near the river channel5, while almost no seedlings had established at the edge of the desert12. The spatial variation in key environmental variables resulted in different plant assemblages at the patch scale which contributes to plant diversity at larger spatial scales. Therefore, the environmental factors that are creating the habitat heterogeneity which in turn affects plant diversity.
The extent of riparian vegetation has declined significantly in response to changes in the environment. The area of the tugai forest declined by 3.0 × 105 ha from 1958 to 1978 in the Tarim Basin and by 4.3× 105 ha from 1950 to 1998 in the Aral Sea Basin51. Furthermore, the P. euphratica forest has decreased from 5.4 × 104 hm2 to 0.67 × 104 hm224, and this species has been listed as an endangered national level three protected plant in China48. The tugai forests thus constitute a highly threatened ecosystem52. Plant species diversity and richness are considered to be the primary objectives of successful restoration53. Our study demonstrates that the plant diversity indices in classes 1 and 2 were higher than those in classes 4 and 5 (Fig. 3). This might indicate that the environmental factors of classes 1 and 2, such as groundwater depth, groundwater salinity, and soil moisture, were more suitable for plant growth than those of classes 4 and 5. Classes 1 and 2 were characterized as tree-shrub-herb structures, which are highly stable and have a stronger sand stabilization ability than that of classes 4 and 538. However, classes 4 and 5 were characterized as shrub-herb and tree-herb structures, respectively. These structures are also effective at sand stabilization. Therefore, we suggest that to protect the riparian plant community, all habitats, rather than some, should be considered for conservation. Conservation managers need to ensure that a sufficient amount of habitat is maintained for the structural and functional sustainability of the riparian forest. This finding has great significance for the restoration and protection of damaged desert riparian ecosystems.
Material and methods
Study area
In this study, the upper reaches of the Tarim River were selected as the study area (Fig. 1). The elevation ranges from 900 m to 1050 m above sea level; the annual precipitation ranges from 50 mm to 70 mm; and the annual pan evaporation is more than 2100 mm12. The average annual temperature is 10.6–11.5 °C, with a minimum and maximum temperature of −27.5 °C and 43.6 °C25, respectively. The vegetation mainly includes Populus euphratica, Tamarix spp., and Alhagi sparsifolia5,12.
Plant quadrats and measurements
In this study, the survey work was performed in July 2016 in the upper reaches of the Tarim River. There are obvious differences in plant diversity from the river channel to the edge of the desert in this area12. The distance from the river channel to the edge of the desert is approximately 30 km12. Therefore, to fully understand the correlations between the plant assemblage and the environmental variables, 77 quadrats were investigated. Nuclear magnetic resonance (GMR, Vista Clara Inc., WA, USA) and ground penetrating radar (RIS-2K, IDS Ingegneria dei Sistemi S.p.A., Italy) were used to ascertain the groundwater depth. Groundwater salinity (GS) was determined based on the method reported in Zhou26. The size of the plant quadrats was 100 m × 100 m. Sixteen sub-quadrats of 25 m × 25 m were used for recording the characteristics of the tree and shrub plants in each plant quadrat. For example, the diameter of trees at breast height (DBH) (breast height = 1.3 m) was recorded for each tree (≥5 cm DBH)12. The height, width, and number of species were recorded for the tree layer and shrub layer. Four sampling quadrats of 5 m×5 m were used for recording the number, height, and width of herbs in each sub-quadrat (25 m ×25 m). A GPS was used to record the quadrat locations.
Soil sampling and measurement
In each quadrat, the soil samples were randomly collected from five location in the upper 20 cm soil layer. The samples were air-dried and then passed through 2 mm sieves before the soil analyses. The soil pH, electrical conductivity (EC), and total salt (TS) were determined using a suspension of the soil sample and deionized water (ratio of 1: 5)27,28. A glass electrode pH meter was used to determine the soil pH27, the dry residue method was used to determine the TS, anda conductivity meter was used to determine the EC28. The neutral double indicator method was used to test for bicarbonate (HCO3−) and carbonate (CO32−). AgNO3 titration and EDTA indirect titration were used to determine sulfate (SO42−) and chloride (Cl−), respectively. Complexometry was used to determine the calcium (Ca2+) and magnesium (Mg2+), the flame photometer method was used to determine the sodium (Na+) and potassium (K+), and the soil moisture was determined by oven-drying the samples.
Calculation of diversity
The plant species diversity was determined using the Simpson diversity index (DS)29, Shannon-Weiner diversity index (H)30, and Pielou evenness index (JSW)31. The following formulae were used:
where S is the number of species, and N is the number of individuals of all the species in a community. In \({P}_{i}={n}_{i}/N\), ni is the importance value of species i in a community, and N is the sum of the importance values of all the species.
Calculation of the relationship between the environment and plant community
Two-Way indicator species analysis (TWINSPAN) method was used to identify the riparian plant communities based on the importance value of the species in all the quadrats7. The plant importance value was calculated according to the following equation7,12:
The diameter at breast height was used for the determination of the relative dominance of the trees, while basal coverage was used for the shrubs and herbs.
TWINSPAN was performed using PC-ORD5.0. Detrended canonical correspondence analysis (DCCA) wasused to analyze the relationship between the environmental factors and the plant community composition7. Two data matrices are required for DCCA. Oneisa species-by-quadrats matrix, and the other one is an environment-by-quadrats matrix. The ordination program CANOCO 4.5 was used to perform the DCCA7. The differences in the species diversity indices, groundwater and soil salinity between the five plant community classes analyzed here were compared individually using multiple comparisons [Tukey’shonest significant difference (HSD) tests at P < 0.05].
Principal component analysis (PCA)32 method was used to assess the comprehensive appraisal value (g) of groundwater and soil salinity in different plant communities. The following formulae was used:
where g is the value of the comprehensive appraisal of the environmental characteristic, n is the number of principal components, xi is the eigenvalue of the ith principal component, \({x}_{i}/\mathop{\sum }\limits_{i=1}^{n}{x}_{i}\)is the weighing factor of the ith principal component, and gi is the ith principal component score. All the principal components extracted from the variables with eigenvalues > 1.0 and a cumulative contribution rate of extraction ≥ 85% were retained32.
References
Goebel, P. C., Palik, B. J. & Pregitzer, K. S. Plant diversity contributions of riparian areas inwatersheds of the northern lake states, USA. Ecol. Appl. 13, 1595–1609 (2003).
Mligo, C. Diversity and distribution pattern of riparian plant species in the Wami River system, Tanzania. J. Plant. Ecol. 10, 259–270 (2017).
Gong, Z. et al. Dynamic simulation of vegetation abundance in a reservoir riparian zone using a sub-pixel Markov model. Int. J. Appl. Earth Obs. 35, 175–186 (2015).
Li, J. et al. Physiological and morphological responses of Tamarix ramosissima and Populus euphratica to altered groundwater availability. Tree physiol. 33, 57–68 (2012).
Stromberg, J. C., McCluney, K. E., Dixon, M. D. & Meixner, T. Dryland riparian ecosystems in the American southwest: sensitivity and resilience to climatic extremes. Ecosystems 16, 411–415 (2013).
Hao, X. et al. Assessment of the groundwater threshold of desert riparian forest vegetation along the middle and lower reaches of the Tarim River, China. Hydrol. Process. 24, 178–186 (2010).
Xi, H. et al. Effects of water and salinity on plant species composition and community succession in Ejina Desert Oasis, northwest China. Environ. Earth. Sci. 75, 138 (2016).
Lamontagne, S., Cook, P. G., O’Grady, A. & Eamus, D. Groundwater use by vegetation in a tropical savanna riparian zone (daly river, australia). J. Hydrol. 310, 280–293 (2016).
Naumburg, E. et al. Phreatophytic vegetation and groundwater fluctuations: a review of current research and application of ecosystem response modeling with an emphasis on Great Basin vegetation. Environ. Manage. 35, 726–740 (2005).
Sarneel, J. M., Kardol, P. & Nilsson, C. The importance of priority effects for riparian plant community dynamics. J. Veg. Sci. 27, 658–667 (2016).
Chen, Y. et al. Desert riparian vegetation and groundwater in the lower reaches of the Tarim River basin. Environ. Earth. Sci. 73, 547–558 (2015).
Zeng, Y. et al. Effect of groundwater depth on riparian plant diversity along riverside-desert gradients in the Tarim River. J. Plant Ecol. 12, 564–573 (2019).
Ma, Y. et al. Relationships between typical vegetations, soil salinity, and groundwater depth in the Yellow River Delta of China. Chin. J. Appl. Ecol. 24, 2423–2430. (In Chinese)(2013).
Zhang, X. et al. Influence of edaphic factors on plant distribution and diversity in the arid area of Xinjiang, Northwest China. Arid Land Res. Manag. 32, 38–56 (2018).
Azizi, S., Tabari, M. & Striker, G. G. Growth, physiology, and leaf ion concentration responses to long-term flooding with fresh or saline water of Populus euphratica. S. Afr. J. Bot. 108, 229–236 (2017).
Peng, H., Thevs, N. & Ott, K. Water distribution in the perspectives of stakeholders and water users in the Tarim River Catchment, Xinjiang, China. J. Water Resour. Prot. 6, 543 (2014).
Thevs, N. Water scarcity and allocation in the Tarim Basin: decision structures and adaptations on the local level. J. Curr. Chin. Affair. 40, 113–137 (2011).
Deng, X. et al. Impact of long-term zero-flow and ecological water conveyance on the radial increment of Populus euphratica in the lower reaches of the Tarim River, Xinjiang, China. Reg. Environ. Change. 15, 13–23 (2015).
Ling, H. et al. Evaluation of the ecological protective effect of the “large basin” comprehensive management system in the Tarim River basin, China. Sci. Total Environ. 650, 1696–1706 (2019).
Glenn, E. P., Nagler, P. L., Shafroth, P. B. & Jarchow, C. J. Effectiveness of environmental flows for riparian restoration in arid regions: A tale of four rivers. Ecol.Eng. 106, 695–703 (2017).
Hou, P., Beeton, R. J. S., Carter, R. W., Dong, X. & Li, X. Response to environmental flows in the lower Tarim River, Xinjiang, China: ground water. J.Environ. Manage. 83, 371–382 (2007).
Ye, Z., Chen, Y. & Zhang, X. Dynamics of runoff, river sediments and climate change in the upper reaches of the Tarim River, China. Quatern.Int. 336, 13–19 (2014).
Xu, H., Wang, X., Ling, H. & Bai, Y. Response of species diversity of desert riparian forest to the changes of groundwater depth in middle reaches of Tarim River. Acta Bot. Boreal. –Occident. Sin. 33, 2017–2076 (2013).
Li, W., Zhou, H., Fu, A. & Chen, Y. Ecological response and hydrological mechanism of desert riparian forest in inland river, northwest of China. Ecohydrology 6, 949–955 (2013).
Ran, Q. et al. Temporal and spatial variation characteristics of natural woodland in the upper reaches of the Tarim River in recent 25 years. Earth. Environ. Sci. 57, 012055 (2017).
Zhou, J. Study on groundwater in Xinjiang. 216 (Yellow River Water Publication, China). (In Chinese) (2010).
McLean, E. O. Soil pH and lime requirement. 199–224 (Wisconsin Publication, USA) (1982).
Bresler, E. B. Limitations in usefulness of irreversible thermodynamics as applied to combined convective and diffusive flow across membranes. Soil Sci. Soc. Amer. Proc. 353, 12–25 (1972).
Simpson, E. H. Measurement of diversity. Nature 163, 688 (1949).
Spellerberg, I. F. & Fedor, P. J. A tribute to Claude Shannon (1916–2001) and a plea for more rigorous use of species richness, species diversity and the ‘Shannon–Wiener’Index. Globalecol. Biogeogr. 12, 177–179 (1949).
Alatalo, R. V. Problems in the measurement of evenness in ecology. Oikos 37, 199–204 (1981).
Li, S. & Liber, K. Influence of different revegetation choices on plant community and soil development nine years after initial planting on a reclaimed coal gob pile in the Shanxi mining area, China. Sci. Total. Environ. 618, 1314–1323 (2018).
Hao, X., Chen, Y. & Li, W. Indicating appropriate groundwater tables for desert river-bank forest at the Tarim River, Xinjiang, China. Environ. Monit. Assess. 152, 167–177 (2009).
Aladin, N. V. & Potts, W. T. W. Changes in the Aral Sea ecosystems during the period 1960–1990. Hydrobiologia 237, 67–79 (1992).
Novikova, N.M. Ecological basis for botanical diversity conservation within the Amudarya and Syrdarya River Deltas. 84–94 (Springer Publication, Berlin, 2001).
Zeng, Y. et al. Effects of climate change on plant composition and diversity in the Gurbantünggüt Desert of northwestern China. Ecol. Res. 31, 427–439 (2016).
Wu, G. et al. Early direct competition does not determine the community structure in a desert riparian forest. Sci. Rep. 8, 4531 (2018).
Wang, X. et al. Relationships between Plant Communities and Environmental Factors in an Extremely Arid Area: A Case Study in China. Pol. J. Environ. Stud. 28, 359–370 (2019).
Rajput, V. D. et al. A review on salinity adaptation mechanism and characteristics of Populus euphratica, a boon for arid ecosystems. ActaEcol. Sin. 36, 497–503 (2016).
He, X. et al. Effects of Tamarisk shrub on physicochemical properties of soil in coastal wetland of the Bohai Sea. Acta Oceanol. Sin. 35, 106–112 (2016).
Barratt-Segretain, M. H. Biomass allocation in three macrophyte species in relation to the disturbance level of their habitat. Freshwater Biol. 46, 935–945 (1997).
Gries, D. et al. Growth and water relations of Tamarix ramosissima and Populus euphratica on Taklamakan desert dunes in relation to depth to a permanent water table. Plant Cell Environ. 26, 725–736 (2003).
Thomas, F. M., Jeschke, M., Zhang, X. & Lang, P. Stand structure and productivity of Populus euphratica along a gradient of groundwater distances at the Tarim River (NW China). J. Plant Ecol. 10, 753–764 (2016).
Yang, Y., Chen, Y. & Li, W. Relationship between soil properties and plant diversity in a desert riparian forest in the lower reaches of the Tarim River, Xinjiang, China. Arid Land Res.Manag. 23, 283–296 (2009).
Mata-González, R. et al. Vegetation as affected by groundwater depth and micro-topography in a shallow aquifer area of the Great Basin. Ecohydrology 5, 54–63 (2012).
Huang, F., Zhang, D. & Chen, X. Vegetation Response to Groundwater Variation in Arid Environments: Visualization of Research Evolution, Synthesis of Response Types, and Estimation of Groundwater Threshold. Int. J. Environ.Res.Public health. 16, 1849 (2019).
Li, J., Zhao, C., Zhu, H., Li, Y. & Wang, F. Effect of plant species on shrub fertile island at an oasis–desert ecotone in the South Junggar Basin, China. J.Arid Environ. 71, 350–361 (2007).
Ling, H., Zhang, P., Xu, H. & Zhao, X. How to regenerate and protect desert riparian Populus euphratica forest in arid areas. Sci. Rep. 5, 15418 (2015).
Huang, T., Pang, Z., Chen, Y. & Kong, Y. Groundwater circulation relative to water quality and vegetation in an arid transitional zone linking oasis, desert and river. Chin. Sci. Bull. 58, 3088–3097 (2013).
Xu, X. et al. Effects of water-table depth and soil moisture on plant biomass, diversity, and distribution at a seasonally flooded wetland of Poyang Lake, China. Chin. Geogr. Sci. 25, 739–756 (2015).
Wortley, L., Hero, J. M. & Howes, M. Evaluating ecological restoration success: a review of the literature. Restor. Ecol. 21, 537–543 (2013).
Thevs, N. et al. Structure, reproduction and flood-induced dynamics of riparian Tugai forests at the Tarim River in Xinjiang, NW China. Forestry 81, 45–57 (2008).
Zhao, J., Lu, G. & Chen, X. Relationship between ecological stoichiometry and community diversity of plant ecosystems in the upper reaches of the Tarim River, China. BioRxiv 2018, 432278 (2018).
Acknowledgements
This study was funded by the Key National Natural Science Foundation project (41671030, U1403281), the Chinese Academy of Sciences (CAS) Project (Y52410) and the project of Thousand Young Talents Program (Chinese Academy of Sciences) (Y772121).
Author information
Authors and Affiliations
Contributions
Y.Z., C.Z. designed the study; Y.Z., C.Z., and F.S. performed the experiments; Y.Z. and C.Z. analyzed the data; and Y.Z., C.Z., F.S., M.S., G.L. and Y.L. wrote the manuscript. All authors read and approved the final manuscript.
Corresponding author
Ethics declarations
Competing interests
The authors declare no competing interests.
Additional information
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
The authors have no competing interests as defined by Nature Research, or other interests that might be perceived to influence the results and/or discussion reported in this paper.
Supplementary information
Rights and permissions
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.
About this article
Cite this article
Zeng, Y., Zhao, C., Shi, F. et al. Impact of groundwater depth and soil salinity on riparian plant diversity and distribution in an arid area of China. Sci Rep 10, 7272 (2020). https://doi.org/10.1038/s41598-020-64045-w
Received:
Accepted:
Published:
DOI: https://doi.org/10.1038/s41598-020-64045-w
This article is cited by
-
Review: Recent progress on groundwater recharge research in arid and semiarid areas of China
Hydrogeology Journal (2024)
-
Crop coefficients of natural wetlands and riparian vegetation to compute ecosystem evapotranspiration and the water balance
Irrigation Science (2024)
-
Coexistence Desert Plants Respond to Soil Phosphorus Availability by Altering the Allocation Patterns of Foliar Phosphorus Fractions and Acquiring Different forms of Soil Phosphorus
Journal of Plant Growth Regulation (2023)
-
A framework of ecological sensitivity assessment for the groundwater system in the Mi River basin, Eastern China
Environmental Earth Sciences (2023)
-
Responses of arid plant species diversity and composition to environmental factors
Journal of Forestry Research (2023)
Comments
By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.