| Insect communities,as a large component of grassland ecosystem,play a vital role in maintaining the stability of grassland ecosystem and providing a good environment for herbage growth.At present,the research on grassland insect community is incomplete in Hebei province.Therefore,the structure,diversity and environmental factors of insect community of different grassland types under three different management modes of enclosed area,mowing area and grazing area in Hongsongwa pasture of Chengde City in the summer of 2018,Hebei Province were investigated to explore the natural grassland insect community under different management modes.The structure and diversity and their correlation with environmental factors provide theoretical basis for the rational implementation of grassland management.The results are as follows:(1)A total of 115 species of insects belonging to 54 families and 8 orders were recorded in natural grassland of Hongsongwa pasture.Among them,the dominant species were 1 order,1 family and 2 species,the common species were 4 orders,17 families and 19 species,the rare species were 8 orders,45 families and 94 species,the pests were 7 orders,33 families and 74 species,and the natural enemies were 4 orders,12 families and 30 species.(2)There were significant differences in species number,individual number,diversity index and evenness of insect communities among different management modes(P<0.05).The similarities of insect communities in enclosure,mowing and grazing areas were low.The change trend of insect community species from high to low was mowing area >enclosure area > grazing area(P<0.05).Enclosure significantly increased the number of insects and species in natural grassland(P<0.05),mowing significantly increased the number of insects(P<0.05),while grazing significantly reduced the number of insects and individuals(P<0.05),but significantly increased the evenness of insects(P<0.05).Different management modes have different effects on pests and natural enemies: for pests,enclosure can significantly increase the number of individual pests(P<0.05),mowing can significantly improve their species diversity(P<0.05);for natural enemies,enclosure can significantly increase the number of species and individuals of natural enemies(P<0.05),grazing can significantly reduce the number of species and individuals of natural enemies(P<0.05),but mowing can significantly increase the number of species and individuals ofnatural enemies(P<0.05).The number of natural enemies was significantly increased(P<0.05).The similarities between pest communities under different management modes and natural enemy communities under different management modes were low.(3)There were significant differences in species number and diversity index of insect communities among different grassland ecological types(P<0.05);the complexity of herbaceous plant communities could significantly increase the number of insect species(P<0.05),and the emergence of shrubs could significantly increase the number of individual insects in meadow.The effects of different grassland types on pests and natural enemies were not identical: for pests,the species number of pests could be significantly increased in the enclosed Sanguisorba officinalis-Artemisia fissure weed meadow(P<0.05),the individual number of pests could be significantly increased in the enclosed area(P<0.05),and the diversity of pest community could be significantly increased in the mowed area(P<0.05).In the enclosed area,Sanguisorba officinalis-Artemisia weed meadow could significantly increase the species diversity of natural enemies(P<0.05),Carex meadow could significantly increase the species diversity of natural enemies(P<0.05),and Sanguisorba officinalis-Artemisia weed meadow and Carex meadow could significantly increase the species diversity of natural enemies(P<0.05).The similarity between pest communities of different grassland types and natural enemy communities of different grassland types was low.(4)Insect community parameters are related to environmental factors.The number of insects,pests and natural enemies was positively or significantly correlated with the height of plant communities.In addition,the number of natural enemies was positively correlated with plant coverage(P<0.05)and negatively correlated with the evenness of plant communities(P<0.05).The coverage and evenness of plant communities had significant effects on the number of natural enemies.There was a significant negative correlation between the number of individuals in insect communities and wind speed(P<0.05),and strong wind was not conducive to the increase of the number of individuals in insect communities.There was a significant positive correlation between pest community diversity and soil N content(P<0.05).Low N environment was conducive to reducing pest community diversity.The number of natural enemies was negatively correlated with soil calcium carbonate(P<0.05),the diversity of natural enemies was positively correlated with soil organic matter content(P<0.05),the homogeneity of natural enemies was negatively correlated with soil pH and compactness(P<0.05),and positively correlated with soil organic matter content(P<0.01);soil pH,organic matter content and soil calcium carbonate had important effects on the community structure of natural enemies: high organic matter content Quantity can improve the diversity of natural enemy community,while high calcium carbonate content can reduce the diversity of natural enemy community;soil with high organic matter content,low pH and compactness can improve the evennessof natural enemy community.There was a significant correlation between pest community diversity and natural enemy community diversity in all grassland ecological types.This study provides a theoretical basis for seeking suitable management models and vegetation restoration of degraded grassland under different management modes in different regions,and confirms that the changes of different management modes and environmental factors can affect grassland ecosystem through insect diversity. |
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