The Role of River Morphodynamic Disturbance and Groundwater Hydrology As Driving Factors of Riparian Landscape Patterns in Mediterranean Rivers

Abstract

Fluvial disturbances, especially floods and droughts, are the main drivers of the successional patterns of riparian vegetation. Those disturbances control the riparian landscape dynamics through the direct interaction between flow and vegetation. The main aim of this work is to investigate the specific paths by which fluvial disturbances, distributed by its components of groundwater hydrology (grndh) and morphodynamic disturbance (mrphd), drive riparian landscape patterns as characterized by the location (position in the river corridor) and shape (physical form of the patch) of vegetation patches in Mediterranean rivers. Specifically, this work assesses how the different components of fluvial disturbances affect these features in general and particularly in each succession phase of riparian vegetation. grndh and mrphd were defined by time and intensity weighted indexes calculated, respectively, from the mean annual water table elevations and the annual maximum instantaneous discharge shear stresses of the previous decade. The interactions between riparian landscape features and fluvial disturbances were assessed by confirmatory factor analysis using structural equation modeling. Two hypothetical models for patch location and shape were conceptualized and tested against empirical data collected from 220 patches at four different study sites. Both models were successfully fitted, meaning that they adequately depicted the relationships between the variables. Furthermore, the models achieved a good adjustment for the observed data, based on the evaluation of several approximate fit indexes. The patch location model explained approximately 80% of the patch location variability, demonstrating that the location of the riparian patches is primarily driven by grndh, while the mrphd had very little effect on this feature. In a multigroup analysis regarding the succession phases of riparian vegetation, the fitted model explained more than 68% of the variance of the data, confirming the results of the general model. The patch shape model explained nearly 13% of the patch shape variability, in which the disturbances came to have less influence on driving this feature. However, grndh continues to be the primary driver of riparian vegetation between the two disturbance factors, despite the proportional increase of the mrphd effect to approximately a third of the grndh effect.

Succession of the Abandoned Rice Fields Restores the Riparian Forest

“…Fluvial disturbances, especially floods, are the main drivers of the successional patterns of riparian vegetation. Those disturbances control the riparian landscape dynamics through the direct interaction between flow and vegetation [ 88 ]. The spatial distribution of riparian vegetation types in different developmental stages reflects the disturbance regime ( Figure 5 and Figure 6 ).…”

Effects of South-to-North Water Diversion Project Cascade Dams on Riparian Vegetation Along the Middle and Lower Reaches of the Hanjiang River, China

“…Natural flow variability is the primary driver of riverine ecosystem functions and structures ( Wang et al, 2015 ). Natural disturbances, such as floods and droughts, are integral components of riparian ecosystems ( Lytle and Poff, 2004 ; Rivaes et al, 2017 ). River water transmission has a positive effect on the migration of vegetation communities along river bank zones, and vegetation responds to climate change and land use changes through river water migration ( Nilsson et al, 2010 ).…”

The combined effect of surface water and groundwater on environmental heterogeneity reveals the basis of beta diversity pattern in desert oasis communities

“…Regarding plant diversity, the coexistence mechanism and diversity characteristics of species respond well to environmental processes such as latitude [ 18 , 19 ], altitude [ 20 , 21 ], and drought stress [ 22 ]. Surface water disturbance and water stress caused by groundwater depth are the two main factors affecting riparian vegetation patterns [ 23 , 24 ]. Surface water disturbance can also be understood as flood pulse, which refers to the sudden fluctuation of the water volume of a river during a flood resulting in overflow [ 25 ].…”