Fine-Scale Distribution Patterns of Phragmites australis Populations Across an Environmental Gradient in the Salt Marsh Wetland of Dunhuang, China

Abstract

The spatial distribution pattern of plants often reflects their ecological adaptation strategy and is formed by their long-term interaction with environmental factors. In this paper, the clonal plant, Phragmites australis, was investigated across environmental gradients, including the wet zone, the transitional zone and the desert zone of the salt marsh wetland of Dunhuang, China. The characteristics and influencing factors of their fine-scale spatial distribution patterns were studied by point pattern analysis, redundancy analysis and simple linear regression. The results show that: (1) the spatial distribution pattern of Phragmites australis changes from aggregation to non-aggregation (random and regular distribution) from the wet zone to the desert zone. (2) The soil water content, pH and salinity all affect Phragmites australis’ spatial distribution intensity. Simple linear regression reveals that the water content in each soil layer, the pH of the deep soil layer and the salinity of the surface and deep soil layers are the main soil conditions of Phragmites australis’ spatial distribution pattern. (3) Phragmites australis’ population characteristics and clonal characteristics also have significant effects on its spatial distribution intensity. Specifically, the intensity of its spatial distribution pattern is significantly positively correlated with its cover, frequency, density, height, biomass, node number, ramet number and stem diameter (p < 0.01), while it is significantly negatively correlated with its rhizome internode length, spacer length and branch angle (p < 0.01). This research clarified the relationship between the spatial distribution pattern of Phragmites australis with soil environmental factors, plant clonal characteristics and population characteristics. The results provide a theoretical basis for understanding the ecological adaptation mechanism of clonal plants and protecting the sustainability of fragile and sensitive inland river wetland ecosystems.

Ecophysiological responses of Phragmites australis populations to a tidal flat gradient in the Yangtze River Estuary, China

“…Appropriate salt supplementation can increase fiber content and biomass, making it healthier and more robust ( Guan et al., 2017 ). Soil salinity plays a dominant role in determining the growth of P. australis , and high salinity limits the population’s survival ( Schenck et al., 2018 ; Jiao et al., 2020 ; Zhang et al., 2021b ; Barbafieri et al., 2023 ). The results showed that the variation coefficients of plant height at low tidal flat and biomass at high tidal flat of P. australis were 37.06% and 44.6%, respectively, indicating that these two morphological traits were largely affected by environmental factors ( Table 2 ).…”

“…Soil water content, pH and salinity all affected the spatial distribution intensity of P. australis . Specifically, the spatial distribution pattern intensity was positively correlated with density, height, biomass and stem diameter ( P < 0.01) ( Jiao et al., 2020 ). Soil salinity plays a leading role in the stoichiometric characteristics of carbon, nitrogen, and phosphorus in P. australis leaves and roots ( Zhang et al., 2021b ), which indicates that soil salinity also indirectly influences the stoichiometric characteristics of soil carbon, nitrogen, and phosphorus in P. australis habitat.…”

Adaptive Strategies Employed by Clonal Plants in Heterogeneous Patches

“…recent studies have demonstrated that some clonal plants may be suitable for repairing and restoring vulnerable habitats. These include (a) clonal plants in karst landform habitats, such as Ficus tikoua [20], Alchornea trewioides [21], and Drepanostachyum luodianense [22]; (b) clonal plants in deserts, such as Calamagrostis epigejos [23], Hedysarum leave [24], Hippophae rhamnoides L., Psammochloa villosa [25], and Stenocereus eruca (Cactaceae) [26]; (c) clonal plants in grasslands, such as Leymus chinensis [27,28], Zoysia japonica Steud [29,30], and Buchloe dactyloides [31]; (d) clonal plants in wetlands, such as Phragmites australis [32,33], Paspalum paspaloides [34], Acorus calamus L., and Spartina alterniflora Loisel [34]. Researchers have also been keen to study the invasion mechanism in invasive clonal plants such as Alternanthera philoxeroides [35], Solidago canadensis L. [36], Carpobrotus edulis [37], and Mikania micrantha H.B.K.…”

Spatial Analysis as a Tool for Plant Population Conservation: A Case Study of Tamarix chinensis in the Yellow River Delta, China

“…As a result, some potential limitations are gradually emerging in the sustainable restoration efficiency [6]. Plant populations present different spatial patterns at different spatial scales under the influence of these biological interactions and ecological processes [7]. Therefore, the potential biological interactions and ecological process within saltcedar populations can be explored through spatial pattern analysis, which will provide theoretical guidance for saltcedar restoration [8][9][10].…”