Ecological Adaptation Strategies Of Three Aquatic Clonal Plants To Heterogeneous And Polluted Habitats

Climate change caused by human activities leads to nitrogen deposition,phosphorus input,and changes in rainfall patterns,resulting in heterogeneous distribution patterns of resources and biological invasion.Various pollutants such as heavy metals,pharmaceutical and personal care products,microplastics and the like are detected in the environment with frequent human activities.Clonal plants grow in environments with spatial and temporal heterogeneity;they can effectively adapt to heterogeneous environments and further increase growth performance through their unique characteristics.The strong clonal ability may help invasive species take advantage of heterogeneous environments.The effects of soil nutrients and water heterogeneity on the growth performance and foraging behavior of exotic and native aquatic plants,and the risk-spreading capacity of aquatic plants in heterogeneous stressed habitats were investigated.Similar life-type invasive species Alternanthera philoxeroides,Myriophyllum aquaticum and native species Ludwigia peploides were selected in these controlled experiments.The results are as follows:1.The effects of soil nutrients and water heterogeneity on the growth performance of invasive species A.philoxeroides,M.aquaticum and native species L.peploides were investigated.Three types of nutrient heterogeneity(two heterogeneous soils consisting of patches of nitrogen and phosphorus,mixed evenly,and low-nutrient soils,and one homogeneous type which the nitrogen and phosphorus soils were mixed homogeneously)and two types of water heterogeneity(the water heterogeneous type of low frequency water supply and the water homogenous types of high frequency water supply)were designed.The results showed that: all three species increased or maintained their growth performance in heterogeneous soils compared with homogeneous soils.There were no significant effects of water heterogeneity on the growth performance of A.philoxeroides and M.aquaticum,the effects of soil nutrient heterogeneity on L.peploides changed with the supply mode of water.In addition,A.philoxeroides and L.peploides showed prominent preferential selective placements of foraging organs in resource-rich patches and further increased whole plant growth.2.To study the risk-spreading ability of aquatic plants in stressed habitats,experiment examined the effects of clonal integration and resource transfer on exotic and native species under the stress environment,which included microplastics and triclosan,four types of pollution stress(controlled,microplastic pollution,triclosan pollution,mixed pollution),two types of directions of resource transmission(acopetal translocation and basipetal translocation)and two types of clone integration(integration and disintegration).The results showed that the clonal integration enhanced the growth performance of A.philoxeroides,M.aquaticum and L.peploides under heterogeneous pollution stress habitats,and the effect of clonal integration was more evident in the acropetal translocation.The mixed pollution of microplastics and triclosan enhanced the growth performance of A.philoxeroides.Moreover,A.philoxeroides,M.aquaticum and L.peploides can alleviate the stress through the different antioxidant enzyme regulation mechanisms.3.To study the risk-spreading ability of L.peploides in polluted environment of microplastic and copper,experiment examined the effect of clonal integration on native aquatic plants under the stress environment of microplastics and copper pollution,five types of pollution stress(controlled,low concentration copper pollution,high concentration copper pollution,mixed pollution of low concentration copper and microplastics,mixed pollution of high concentration copper and microplastics)and two types of clone integration(integration and disintegration)were set up.The results showed that with clonal integration,the plant height of L.peploides was significantly increased by mixed pollution.In contrast,the total biomass of L.peploides was decreased by adding copper pollution alone,and L.peploides can alleviate the stress through the different antioxidant enzyme regulation mechanisms.In conclusion,these three clonal plants have high adaptability to heterogeneous and pollution stress environments due to their clonal integration and foraging behavior,and this adaptation ability is more likely to contribute to the invasion of A.philoxeroides.