Understanding wetland plant dynamics in response to water table changes through ecohydrological modelling

Abstract

Vulnerability of wetland vegetation to water table changes is a widely studied topic in the field of ecology. Extreme flood or drought conditions imposed on wetlands cause disappearance of plants or shift in the vegetation regime. The recovery of such plant compositions is of particular importance when the wetland is subjected to frequent water table fluctuations resulting from land use changes and requires knowledge of mechanisms underlying evolution of plant growth to changing hydrologic conditions. We used a spatially varying, coupled groundwater–vegetation growth model to investigate the survival mechanism of wetland herbaceous plants. The plants were subjected to long‐term water table drainage because of land use changes that caused the disappearance of one of the species composition. In an effort to revive the disappeared species, hypothetical soil saturation was introduced onto the study domain through elevated water table level. Even though the system had returned to hydrologically favourable environment, the disappeared species was unable to recover, which in turn led to the evaluation of factors that determine the re‐emergence of the species through sensitivity analysis. The results of the sensitivity analysis showed that the disappeared species recovered during scenarios of reduced duration of drawdown, increased assimilation rates and increased competitiveness. The analysis also showed that the competitiveness of the plants, which was modelled by the classic Lotka–Volterra algorithm, supersedes any of the unfavourable plant growth characteristics. The results of this study demonstrated the ability of the groundwater–vegetation response model to facilitate an understanding of plant development and a hierarchy of important factors that promote their growth in altered hydrologic conditions. Copyright © 2012 John Wiley & Sons, Ltd.

Monitoring Spatial and Temporal Dynamics of Flood Regimes and Their Relation to Wetland Landscape Patterns in Dongting Lake from MODIS Time-Series Imagery

“…The mechanism of vegetation succession is a part of the most important theoretical foundations for wetland restoration and conservation, and has become a central issue of wetland science [1][2][3][4][5][6][7]. Although several factors (such as soil nutrients and moisture, as well as the predation, competition, and promotion among wetland plants) influence the succession of wetland vegetation, hydrological conditions are the most significant and complicated elements [8,9].…”

An approach for modelling the effects of changes in hydrological environmental variables on tropical primary forest vegetation

“…Milzow et al (2010) have studied the future ecoregion distributions within the Okavango Delta wetlands based on the hydrological simulations and future climate and development scenarios. More recently, Chui et al (2011) have developed a model coupling ground water movement and plant growth dynamics for wetlands, and have used the model to understand the ecohydrological impact due to hypothetical construction drainage, and the hierarchy of factors that promote plant's growth in altered hydrologic conditions (Palanisamy and Chui, 2012). Most of such models may be viewed as proof -of -concept models due to the inherent difficulties in building practically applicable models.…”

Empirical Equations to Predict the Characteristics of Hyporheic Exchange in a Pool‐Riffle Sequence

“…Ecosystem functions and physicochemical and biological processes are generally sensitive to hydrological conditions (Palanisamy and Chui ), and those in the hyporheic zone are sensitive to the dynamics of HE (Storey et al ). The flux and scale of HE determine the amount and extent of the vertical and horizontal penetration of solute‐laden surface water into the streambed (Tonina ; Zarnetske et al ).…”

“…HE transports suspended and dissolved solutes such as nutrients, contaminants, organic carbon, and oxygen into the hyporheic zone (Tonina 2012). With the supply of water and solutes, the hyporheic zone governs important physicochemical processes such as redox reactions, contaminant filtration, and the cycling of nitrogen, carbon, and phosphorus, and creates a rich biocenosis composed of species that temporarily and Ecosystem functions and physicochemical and biological processes are generally sensitive to hydrological conditions (Palanisamy and Chui 2013), and those in the hyporheic zone are sensitive to the dynamics of HE (Storey et al 2003). The flux and scale of HE determine the amount and extent of the vertical and horizontal penetration of solute-laden surface water into the streambed (Tonina 2005;Zarnetske et al 2011).…”