| The global precipitation pattern has changed significantly in the changing climate scenario.Precipitation changes regulate plant community characteristics and functional traits by altering soil physical and chemical properties on terrestrial ecosystems.Exploring how precipitation changes affect plant community characteristics and functional traits is essential to assessing variation in ecosystem processes in future climate change scenarios,as community characteristics and functional traits are fundamental elements in understanding the structure and function of terrestrial ecosystems.In recent years,most studies of the effect of precipitation changes on plant community characteristics and functional traits have focused on grassland and forest ecosystems.However,with few studies on estuarine wetland ecosystems and underlying mechanisms remain elusive.We examined the effects of precipitation changes on plant community characteristics and functional traits according to a manipulated precipitation experiment in wetland of the Yellow River Delta.The field manipulative experiment with five precipitation treatments,including 60% decreased precipitation,40% decreased precipitation,natural precipitation(as control),40% decreased precipitation and 60% decreased precipitation treatment.The main results were as follows:(1)Precipitation changes altered soil physical and chemical properties of wetland in the Yellow River Delta.Compared with the control,the 40% decreased precipitation treatment significantly decreased soil moisture.Increased precipitation treatments significantly decreased soil electrical conductivity compared with the 40% decreased precipitation treatment.The 60% increased precipitation treatment significantly decreased soil p H.The contents of soil total nitrogen and total phosphorus were lower than the national average among different precipitation treatments in wetland of the Yellow River Delta.Compared with the control,the content of soil available phosphorus decreased slightly,but did not reach a significant level.(2)Precipitation changes altered plant community compositions,species importance values varied significantly among different precipitation treatments.The 40% decreased precipitation treatment significantly increased importance value of Suaeda salsa than other precipitation treatments.Compared with the control and 60% decreased precipitation treatments,the 40% decreased precipitation treatment significantly decreased importance values of Suaeda glauca and Tripolium vulgare.Triarrhena sacchariflora only appeared in the increased precipitation treatments,and the important value increased with increasing precipitation.The increased precipitation treatments significantly decreased importance values of Suaeda salsa,Suaeda glauca and Tripolium vulgare.Precipitation changes had no significant effect on the absolute dominance of Phragmites australis.(3)Precipitation changes significantly altered the growth characteristics of plant community in wetland of the Yellow River Delta.The plant community height increased significantly with increasing precipitation.Meanwhile,the community density and coverage increased first and then decreased with increasing precipitation.The growth characteristics of plant community are mainly affected by soil electrical conductivity and available phosphorus.In addition,the growth characteristics of plant community are mainly altered by soil electrical conductivity and available phosphorus with precipitation changes.Soil electrical conductivity were negatively related to plant community height,and positively related to community density.Soil available phosphorus had significantly positive relationships with community coverage and density.(4)Precipitation changes significantly altered functional traits of Phragmites australisin wetland of the Yellow River Delta.The plant height,stem diameter,leaf length,leaf width,specific leaf area,photosynthetic rate,transpiration rate and stomatal conductance of Phragmites australis increased significantly with increasing precipitation.The water use efficiency of Phragmites australis decreased significantly with increasing precipitation.The leaf nitrogen phosphorus ratio of Phragmites australis is greater than 16 with precipitation changes,indicating that the Phragmites australis are limited by phosphorus and not limited by nitrogen in wetland of the Yellow River Delta.Meanwhile,the functional traits of Phragmites australis were significantly correlated among different precipitation treatments,which indicated that there were significant synergies and trade-offs between the functional traits of Phragmites australis.In addition,the functional traits of Phragmites australis are mainly altered by soil electrical conductivity and moisture with precipitation changes.Soil electrical conductivity were negatively related to plant height,leaf length,photosynthetic rate,transpiration rate and stomatal conductance,and positively related to water use efficiency of Phragmites australis.Soil moisture had significantly positive relationships with photosynthetic rate,transpiration rate and stomatal conductance of Phragmites australis.Therefore,increased precipitation made Phragmites australis tend to adopt resource acquisitive strategy,while decreased precipitation made it tend to adopt resource conservation strategy.In conclusion,our results revealed that precipitation changes regulate plant community characteristics and functional traits by altering soil physical and chemical properties in a estuarine wetland.This study further complements and perfects the process and mechanism of effects of precipitation changes on plant community of estuarine wetland,and is of great significance to explore the dynamic changes of estuarine wetland ecosystem. |
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