Effects of hydrologic modifications to riparian plant communities in a large river system in northern China

Abstract

Hydrologic modifications to rivers caused by anthropogenic activity have major impacts on riparian ecosystems. Alterations to the hydrologic regime and their interactions with natural environmental parameters exert selective pressures on riparian vegetation, resulting in adaptations to specific flow attributes. However, few studies have attempted to detect these effects under multiple hydrologic conditions, especially for rivers in semi-dry and semi-humid regions. Using the ''space-for-time substitution'' method, we investigated the effects of hydrologic modifications to the riparian plant community along the Yongding River of northern China, by comparing community structure metrics (diversity, plant moisture affinity group, and lifespan) and a function metric (biomass) under three streamflows (perennial, seasonal and dried-up). Among these streamflows, seasonal flow reaches had the greatest plant diversity. Responses of plant moisture group and lifespan were inconsistent in different hydrologic stages, although they varied significantly (P < 0.01). Annuals and biennials greatly increased from perennial to seasonal streamflow ($59 %), while perennials decreased ($41 %). However, from seasonal to dried-up flow, the percentage of mesics and xerics increased by 12.8 and 11.8 %, respectively, while hydrics decreased dramatically (by 24.6 %). Perennial flow had significantly greater aboveground biomass (P < 0.05) than the other two flows. Hydrologic conditions and their related soil nutrients were the main driving factors of community structure and function, which explained 21.0 and 18.0 % of variation, respectively. These findings reveal the response process of the riparian plant community during hydrologic modification from perennial to dried-up streamflow.

The Effects of Edaphic Factors on Riparian Plants in the Middle and Lower Reaches of the Hanjiang River, China

“…Redundancy analysis (RDA) results showed that soil moisture strongly influenced the species hydrophilic types. Hydrophilicity of plants is the most direct manifestation of their adaptation to the environment [26]. Generally, hydric and mesic species have certain flood resistance abilities, with the majority having both vegetative propagation and seed reproduction capabilities, enabling them to quickly germinate after flood events [27].…”

Large‐scale environmental flow results in mixed outcomes with short‐term benefits for a semi‐arid floodplain plant community

“…However, multi‐taxa models are rarely applied to plant research (but see Chen, Kery, Plattner, Ma, & Gardner, ) and default methods of determining community patterns include modelling community summary metrics (e.g. Laine, Kettenring, & Roper, ; Xiu, Gerisch, Ilg, Henle, & Ouyang, ) or multivariate techniques such as non‐metric multidimensional scaling (e.g. Hough‐Snee, Roper, Wheaton, & Lokteff, ) or detrended correspondence analysis (e.g.…”

“…Hough‐Snee, Roper, Wheaton, & Lokteff, ) or detrended correspondence analysis (e.g. Xiu et al., ). Although most of our metrics capture general community patterns fairly well, we see the additional taxa‐specific information and the predictive capabilities of our modelling technique as a substantial advantage when attempting to inform plant community management.…”

Insights from long-term variations in gravel riverbed topography as an indicator of vegetation–morphology interactions

“…Flooding shapes the fluvial landforms and habitat gradients for the establishment and development of riparian vegetation [1][2][3][4][5]. Consequently, the flow regime is critical in the formation of plant communities [6][7][8][9][10], seed banks [11][12][13] and nutrient dynamics [14][15][16][17][18]. Riparian vegetation consistently adjusts to flood disturbances and sedimentation process (erosion and deposition of sediments) driven by the flooding history to maintain a dynamic equilibrium, with new conditions correlated with the elevation relative to the river water level [19][20][21][22][23][24].…”