| Ecological restoration and conservation works as a key factor for connecting reservoir riparian zones and human-intervened river shorelines. The restored sites recover former connections for maintaining integration, which is crucial for ecological safety of whole river system. Factors influencing ecological restoration and conservation are concerned in this paper. Species dominance and community composition collected by field investigation in middle and lower reaches of Han River reveal species composition and community structure, working as background for further analysis. Database propagule dispersal traits with distribution pattern, combining flotation experiment, and model species’SSR molecule study explain dispersal mechanisms in riverside, and the potential dispersal impact on community construction. While database species’traits with important value, and species interactions are used to explain community construction mechanism in different angles. A controlled chamber experiment was conducted to study species life-history strategies in community construction. Our analyses enrich dispersal and community construction principles mechanism principles in riversides. The results could be used to direct community restoration and conservation in riparian zones and river shorelines.1. Totally 165 sites with 3276 quadrats were sampled in investigation.76 sites with 983quadrats from 29 rivers were selected as river shoreline sites, while 89 sites with 2293quadrats from 87 reservoirs as reservoir riparian sites.57 families,147 genera and 194angiosperm species were detected. River shoreline sites contained 48 families,121 genera and 160 species; reservoir riparian sites contained 39 families,108 genera and 139 species. Analysis reveals large families with abundant species and small families with only one species widely distributed in both areas. The geographical distributions of these species were dominated by the Cosmopolitan, Pantropic and North Temperate, which highly correlated with its geographic and climate conditions.2. Overall, in site level, the differences of community compositions, community structures, and community diversities between riparian zones and reservoir shorelines were not significant. Reservoirs riparian zones and river shorelines were highly connected to each other. The species richness, Shannon-Weiner diversity and Simpson diversity in reservoir riparian zones were slightly higher than river shorelines. Numerical taxonomy categorized investigation sites into 7 classes,5 of which mainly on riparian zones and 2 on river shorelines. Edificators were dominated by Poaceae, Asteraceae and Cyperaceae; indicator species contained Polygonaceae as well. Although spatial analysis displayed obvious distribution pattern, life-history, life form and propagule dispersal traits showed no significant differences.3. Twenty dispersal traits with 39 indicators were summarized in study. Comparing dispersal traits with frequentness, anemochory indicator-terminal velocity, and hydrochory indicator-flotation, with one flotation related appendages showed significant relationship with plant dispersal potentials, working as vital factors influencing propagule disperse. The significant positive appearances increased by flotation, and recorded percentages of Anemochory reveal that hydrochory and anemochory are important dispersal mechanisms in study areas.4. Flotation experiment studied relationships of 43 species seed flotation ability with their distribution frequency.60% of them Q50 (50% seeds submerged) took more than 2 days.86% Q50 also more than 2 days. It indicates most of species have potentials for long distance dispersal by hydrochory, which further imposes the importance of hydrochory in riparian zones and river shorelines.5. With an amazing flotation ability, Cyperus michelianus is widely distributed in investigated areas, especially in riparian zones. It then selected as a model species to study plant dispersal.31 sites with totally 321 samples were taken in field survey.131 pair SSR markers were used to detect potential gene differences for genetic geography comparison. Result reveals that Cyperus michelianus communities in middle and downstream Han river basin share highly genetic similarities, in a same gene pool.6. The study of 27 plant traits,67 indicators with dominance revealed six traits were important in community construction. Flotation, flotation related appendages, LDMC and semi-rosette leaf distribution along the stem enriching the dominance; while two vegetative clonal growth organs poor positive. In investigation areas,42 species in riparian zones,25 species in river shorelines, and totally 39 species in all sites had a frequency larger than 20%. Positive and negative species interaction both existed in study areas, with a quite equally distributed amount, but different degree. Positive interactions with higher r value dominated investigated. Overall, hydrochory and vegetative propagules are important factors influencing community construction. In river shorelines, resistance works more important than competition in community construction.7.Four elevation-different annual species, Panicum bisulcatum, Cyperus michelianus, Fimbristylis littoralis and Eclipta prostrata, which widely distributed in study area, were chosen as study materials for water-controlled chamber experiment. Initial sowing dates were used as the controlled factor to simulate hydrologic disturbances. Plant life history traits were collected for studying life history adaptation strategies. Results show that all four species produced non-dormant seeds that survived prolonged submergence; germination percentage was independent of the time of exposure by receding waters. Although growth was reduced as a result of shorter growing seasons, all four species completed their life cycles and produced seeds before winter. All species responded to later establishment with a reduced vegetative growth period before seed production.Our results reveal, in Han River basin, Cyperus michelianus, an edificator in waterfront zones, has strong flotation ability, and flexible life history adaptation strategies, reservoir riparian zones and river shoreline sites show high integration in plant compositions and community functional traits. Plant life history strategies work as an adaptation mechanism for highly changeable hydrologic disturbances. Hydrochory is vital for propagule dispersal; while hydrochory and vegetative growth are vital for community construction. |
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