Impact Of The Exotic Plant, Alternanthera Philoxeroides(Mart.)griseb., On Soil Ecosystem

Alternanthera philoxeroides originated in South America,and was first introduced in China in 1930 s and rapid spread,growth and production,has been one of the serious environmental weeds in China.Alternanthera philoxeroides invasion will rapidly colonized with diffusion,and competed for resourses with native species,caused by invasive species diversity decreased,crop yield reduction and eutrophication of water,also easy to breed mosquitoes,affect the environmental sanitation.Invasive plants were closely related to biological diversity and underground ecological processes at invaded areas through plant-soil feedback interaction.This paper chose invasive plant A.philoxeroides as the research object,through the traditional method of measuring physical and chemical properties,soil fauna Tullgren method and microbial high-throughput sequencing method,study on the different degrees of invasion on soil physical nature,animals and soil microbial community diversity,aimed at understanding the Alternanthera philoxeroides on soil ecosystem effects,and for management and restoration of Alternanthera philoxeroides invasion ecological functions to provide a theoretical basis.1.The imapcts of the invasive plant on soil physicochemical propertiesWith the same depth mixed soil sample to do the soil properties analysis,the result shows: the soil organic matter,total nitrogen,available potassium,available phosphorus content and water content was increased with the degree of invasion,which soil organic matter and total nitrogen content in heavily invaded district was 4.2 times and 3.5 times corresponding to non-invaded area,and 1.4 times and 1.5 times corresponding to slight invaded area;Soil physical and chemical properties of different depths at the same invasion intensity difference shows: with the soil depth increased,the soil organic carbon,total nitrogen,potassium levels were significantly decreased,showed significantly surface accumulate in the vertical distribution.2.The impacts of the invasive plant on soil animal communityFour surveys were isolated 2406 soil meso-and micro animals,belonging to 7 classes,16 orders and 25 classes.The dominant population was mites and Collembola,which accounted for 64.52% of the total soil animals.With Alternanthera philoxeroides invasion degree increases,the total individual number of soil animals showed increased first and then decreased trend,group number tends to be stable;Of intrusion regional diversity index analysis indicated that from slight invaded area to heavilyinvaded area,the community diversity index showed intermediate high on both sides of the lower trend,means that Alternanthera philoxeroides invasion to the degree of influence of soil animal community and moderate intrusion condition is more suitable for soil animals to survive.In different soil depth of soil animal community diversity survey found that,with the increase of soil depth,the micro soil fauna number and individual density in the vertical direction the obvious surface accumulation,showed that soil animal is suitable for living in the soil nutrient is abundant rich shallow soil.Through the analysis of correlation between soil properties and soil animal community.The results show that the influence of the distribution of soil animal may be affected by the content of total K.3.The impacts of the invasive plant on soil microbial communityThis study used high-throughput sequencing technology.In the investigation of bacteria,four samples were obtained from 77260 16 srDNA sequences,which were divided into 4596 OTU,and 32 groups were divided into the classification level of the phylum.Proteobacteria was a total of dominant species,in the four species plots were accounted for 45% of the above;ratio of Bacteroidetes,Acidobacteria and Verrucomicrobia was decreased with the increase of the intrusion,Proportion of actinobacteria and Chloroflexi increases with the increase of intrusion;With Alternanthera philoxeroides invasion of increased bacterial diversity index showed a trend of first increased and then decreased,moderate invasion of diversity of the region a higher degree,invasion area and non-invaded area were difference significantly.On fungal investigation,four samples were obtained 51481 sequences,943 OTU and in phylum classification level is divided into 5 groups,Ascomycota as the dominant microflora accounted for 88.5%;Variation in the degree of invasion of fungal community structure was not significantly affected,similar difference was also not significant,Alternanthera philoxeroides invasion on the fungal community diversity effect still need further investigation.