Characteristics Of Soil Nematode Community In Bayanbulak Grassland Under Human Disturbance

Soil nematodes are sensitive to environmental changes and can develop in coordination with the environment for a long time.It can not only reflect the degree of disturbance of the soil ecosystem by external activities,but also indicate the health of the soil ecosystem.Xinjiang Bayanbulak has a unique geographical location and climate characteristics,making it extremely sensitive to climate change and human disturbance.In this study,grassland under different water conditions without human disturbance,degraded grassland affected by grazing intensity,and long-term enclosed grassland(grassland meadow,meadow grassland and typical alpine grassland)are the research objects.The soil nematodes were separated by the continuous extraction method of shallow disc separation and sucrose centrifugal flotation.Stereoscopic and optical microscopes were used for quantitative statistics and identification,the characteristics of nematode community structure and the determination of soil environment related indexes were used,carried out research on the influence of human disturbance on soil nematode community structure characteristics in Bayanbulak grassland,understands soil nematode community structure characteristics under different disturbances,and reveals soil nematodes The relationship between community structure characteristics and changes in soil environmental factors provides important theoretical support and practical reference for the evaluation of the soil environment of the grassland ecosystem,the optimization of grassland ecosystem protection and management strategies,and the early warning of grassland degradation.The results show:(1)The soil nematodes in Bayanbulak grassland are mainly distributed in the 0?5 cm soil layer,and the number of soil nematodes decreases with the increase of soil depth;the soil nematodes obtained from the three water conditions of the undisturbed plot belong to 25 families 43 genera.The soil nematodes obtained from the grazing plot belonged to 32 families and 38 genera,and the soil nematodes obtained from the three grassland types under enclosure conditions belonged to 30 families and 56 genera.(2)Helicotylenchus were the dominant genus under natural conditions.Mesodorylaimus were the dominant genus in the perennial and seasonal water accumulation areas,while Eucephalobus were the dominant genus only in the seasonal water accumulation areas;the dominant genus of soil nematodes under light and moderate grazing intensity was mainly Plectus and Prodorylaimus;the dominant genera of soil nematodes under heavy grazing intensity were Acrobeles and Microdorylaimus.The dominant genera inside and outside the fence was different for different grassland types after long-term enclosure.The dominant genera in the grassland meadow fence were Mesodorylaimus and Aporcelaimus,the dominant genera outside the fence were Eucephalobus,and the common dominant genera inside and outside the fence were Helicotylenchus,Tylencholaimus,Eudorylaimus and Criconema;the dominant genera in the meadow grassland fence were Eucephalobus and Rotylenchus,the dominant genera outside the fence were Tylenchus,and the common dominant genera inside and outside the fence were Helicotylenchus.The dominant genera in the typical alpine steppe fence were Leptolaimus and Microdorylaimus,and the dominant genera outside the fence were Acrobeles,Tylencholaimus,Helicotylenchus,and Eudorylaimus.(3)Both undisturbed grassland and enclosed grassland have the highest proportion of plant parasitic nematodes.Undisturbed grassland has the largest number of soil nematodes under seasonal stagnant water conditions;plant parasitic nematodes account for the highest proportion of nutrient groups under different water conditions,reaching 41.06% and 48.77% under perennial stagnant water,perennial stagnant water,and perennial dry conditions,respectively 41.06%,48.77% and 83.69%.The number of nematodes under moderate grazing intensity was significantly higher than that of light grazing and heavy grazing(P<0.05).Under grazing disturbance,the nematode nutrient groups in the soil were mainly bacterivore nematodes.The ratios were 43.47%,39.55% and 39.81%.The nutrient groups of nematodes in the soil outside the fence of grassland meadows are mainly plant parasitic nematodes(47.96%),and the proportion of omnivores predator nematodes in the fence was the highest(40.23%).The proportion of plant parasitic nematodes both inside and outside the fence of meadow grassland and typical alpine grassland was the highest,and the proportion of plant parasitic nematodes inside and outside the fence of meadow grassland is higher than that outside the fence of typical alpine grassland.(4)Through multiple ecological index evaluations of soil nematodes,it is concluded that the seasonal water area is relatively stable relative to the other two water conditions,and the soil ecosystem food web under moderate grazing intensity is relatively stable compared with the other two grazing intensity soil ecosystem food webs.Stable.The soil health status of grassland meadows and typical alpine grasslands has improved significantly after the existing years.