Response Of Benthos To Habitat Change In Paddy Field And Its Safety Assessment

In the present work,benthic animals wereused as indicator organisms in order to understand their response to habitat change in rice fields and evaluate their safety.three aspects of rice field habitat changes were studied in the rice growing area of Shanghua village,Dongjiao,Xiangxiang Township,Xiangtan City,Hunan Province,for three years.Based on the analysis of individual number,community similarity,dominant species distribution,species richness,community diversity index,evenness index and dominant concentration index of benthic fauna in rice fields,some conclusions were drawn,it is expected to provide reference basis for agricultural production and ecological security.1.Application of organic fertilizer to increase the content of relevant elements in paddy soil.The application of organic fertilizer and "Genguowang" compound microbial fertilizer in paddy field can improve the soil fertility and increase the content of available phosphorus,available nitrogen,total nitrogen,organic matter and total potassium.Compared with chemical fertilizer,compound microbial fertilizer could effectively maintain the content of alkali-hydrolyzed nitrogen in paddy soil.The results also showed that the content of available potassium in the two types of paddy fields decreased greatly.It is suggested that the proportion of organic fertilizer should be increased and the proportion of chemical fertilizer should be increased in order to maintain soil nutrient requirement.2.Effects of organic fertilizer application on zoobenthos community in rice field and ecological securityOne-crop rice was planted in 2017 and 2018.In 2017,RPOM collected 17 species of benthos,RPCF collected 19 species of benthos and 13 common species,the similarity of community was 0.8263.The dominant species of RPOM and RPCF were 4 species and 2 species in common.In 2018,16 species of zoobenthos and 11 species of community were collected from rice fields in RPOM and RPCF,and the community similarity was 0.6875.There were 1 dominant species of RPOM and 2 dominant species of RPCF.Limnodrilus Hoffmeisteri was the common dominant species.The parameters of zoobenthos in paddy field showed that compared with chemical fertilizer application,the application of compound microbial bacterial fertilizer of "Genguowang" in paddy field,the community as a whole had no significant impact on the species composition and structure,diversity,dominant species composition and community evenness of the benthic community in rice fields.However,it has a significant effect on the individual number of benthic animals per unit volume,that is,it reduces the number of individual of the dominant species,and has no obvious effect on other benthic animals.3.Response of rice benthos to different rice varieties in paddy fieldEarly and late rice were planted in 2018,and three different varieties of rice were planted each season.Early Rice JY433 collected 29 species of benthos,TY535 collected 20 species of Benthos,WFY317 collected 21 species of benthos,14 common species.LY228 collected 20 species of benthos,YY518 collected 17 species of benthos,5YYZ collected 24 species of benthos and 13 common species.Limnodrilus Hoffmeisteri of three early rice varieties.It was the absolute dominant species in three rice fields,and there was no significant difference among the dominant species of each variety.Three species of late rice midges Bezzis Sp.And Limnodrilus Hoffmeisteriwere the dominant species in three groups.The experimental parameters showed that there were no significant adverse effects on the macrozoobenthos community between early rice and late rice,such as no significant differences in species composition,dominant species composition,and high similarity of the community,however,the abundance of benthos in JY433 was significantly higher than that in TY535 and WFY317,and that in late rice 5YYZ was significantly higher than that in LY288 and YY518.All varieties of early and late rice are suitable and safe for rice planting.4.The experiment cycle of response of benthos to heterogeneousIn 2018 and 2019,the HHR collected 10 species of benthos,the LHR collected 12 species of benthos,7 common species,and the community similarity was 0.6364.In 2019,the HHR collected 12 species of benthos,the LHR collected 13 species of benthos and 11 common species,the similarity of the two habitat communities was 0.8800.The parameters showed that the species composition of the benthic communities of HHR and LHR were similar.But the species richness and the number of individuals per square meter of benthic community in HHR were lower than those in LHR,diversity index and evenness index were higher than that in LHR,dominance concentration index HHR was lower than that in LHR,but there was no significant difference.From the time dynamic analysis,the number of individuals at booting stage was HHR very significantly or significantly lower than LHR.The highly heterogeneous environment is helpful for species diversity protection,community development and ecological stability of benthic animals.