Effects of water-table depth and soil moisture on plant biomass, diversity, and distribution at a seasonally flooded wetland of Poyang Lake, China

Abstract

Hydrological regime has been widely recognized as one of the major forces determining vegetation distribution in seasonally flooded wetland. Poyang Lake, the largest freshwater lake in China, has been encountering dramatic changes in hydrological conditions in last decade, which greatly influenced the wetland vegetations. To explore the relationships between hydrology and vegetation distribution, water-table depth, soil moisture, species composition, diversity and biomass were measured at a seasonally flooded wetland section at Wucheng National Nature Reserve. Three plant communities, Artemisia capillaris, Phragmites australis and Carex cinerascens communities, were examined which are zonally distributed from upland to lakeshore with decreasing elevation. Canonical correspondence analysis (CCA), spearmen correlation and logistic regression were adopted to analyze the relationships between vegetation characteristics and hydrological variables of water-table depth and soil moisture. Results show that significant hydrological gradient exist along the wetland transect. Water-table demonstrates a seasonal variation and is consistently deepest in A. capillaris community (ranging from -0.5 m above ground to +10.3 m below ground), intermediate in P. australis community (-2.6 m to +7.8 m) and shallowest in C. cinerascens community (-4.5 m to +6.1 m). Soil moisture is lowest and most variable in A. capillaris community, highest and least variable in P. australis community, and intermediate and moderate variable in C. cinerascens community. The CCA ordination indicated that variables of water-table depth and soil moisture are strongly related to community distribution, which explained 81.7% of the vegetation variations. Species diversity indices are significantly positively correlated with soil moisture and negatively correlated with moisture variability, while above-and belowground biomass are positively correlated with moisture. Above-and belowground biomass present Gaussian models along the gradient of average water-table depth in growing season, while species diversity indices show bimodal patterns. The optimal average water-table depths for above-and belowground biomass are 0.8 m and 0.5 m, respectively, and are 2.2 m and 2.4 m for species richness and Shannon-Wiener indices, respectively. Outcomes of this work improved the understandings of the relationship between hydrology and vegetation.

Temporal and spatial variations of vegetation in a riparian zone of South Korea

“…4). Moisture content was the primary factor driving vegetation patterns in a riparian zone as shown in other studies (Xu et al 2015). Variations in soil moisture content are due to elevation above the water level and distance from the water front.…”

The Influence of Hydrometeorological Conditions on Changes in Littoral and Riparian Vegetation of a Meromictic Lake in the Last Half-Century

“…The shift of vegetation zones and expansion of plants into open water would not have been possible if not for the large fluctuations in the water level in the lake and the continuing trend of a lowering water level observed since the beginning of the 1990s (Figure 4). In addition to the hydrology of the reservoir itself and the morphology of the lake basin, the wind exposure and hence the height of the waving were very important factors affecting the development of vegetation [45,46].…”

Seasonal variability of groundwater level effects on the growth of Carex cinerascens in lake wetlands

“…Surprisingly, previous studies testing the effects of groundwater level on plant growth were mostly conducted during few months and during one growing season only ( e.g., Hanke, Ludewig, & Jensen, ; Kotowski et al, ; Li et al, ). Climatic parameters like temperature and precipitation can strongly vary across the seasons (Xu et al, ) and some previous studies reported that the main hydrologic factors for plant growth and vegetation distribution differ between spring and autumn (Dai et al, ; Runhaar et al, ). However, to our knowledge, the extent to which variations in groundwater level could affect plant parameters during distinct plant growing periods ( i.e., spring vs. autumn) in relation to varying meteorological conditions remains poorly studied.…”

“…Groundwater level is crucial for wetland development and maintenance, as it affects community assembly and composition (Deane et al, 2018;Hose, Bailey, Stumpp, & Fryirs, 2014;Valdez, Hartig, Fennel, & Poschlod, 2019) as well as the stability of plant communities (Ridolfi, D'Odorico, & Laio, 2006;Runhaar, Witte, & Verburg, 1997). Groundwater level is also a key factor determining plant growth and reproductive parameters (Booth & Loheide, 2012;Steed, Dewald, & Kolb, 2002) as the depth of the groundwater table strongly controls water, oxygen, and nutrient availability for plants (Kotowski, Andel, Diggelen, & Hogendorf, 2001;Muneepeerakul, Miralles-Wilhelm, Tamea, Rinaldo, & Rodriguez-Iturbe, 2008;Paul et al, 2003;Xu, Zhang, Tan, Li, & Wang, 2015). For example, Van der Valk and Baalman (2018) found that increasing groundwater level induced greater species richness and shoot density of meadow plant species in a mesocosm experiment.…”