Effects Of Seasonal Rotational Grazing And Mowing On Soil Nematodes In Typical Grasslands Of Inner Mongolia

Nematodes are important members of soil fauna.They have complex interactions with other members of soil fauna,and play an important role in promoting the material cycle and energy flow of ecosystems and maintaining the stability of the system.Grazing and mowing are the most important utilization and management measures of typical grasslands.The responses of soil nematodes to seasonal grazing and mowing in typical grasslands of Inner Mongolia were investigated in spring,summer and autumn with 8 treatments including 5 successive seasons grazing?T₁?,5 seasonal rotational grazing?T₂,T₃,T₄,T₅ and T₆?,autumn mowing?T₈?and no CK.The aim was to provide basis for rational utilization of grassland resources.The main results are as follows:?1?Compared with CK,grazing and mowing all season reduced the abundance,genera and diversity of soil nematodes and increased the biomass of soil nematodes.Moreover,the community abundance and Shannon-Weiner diversity index of soil nematode in mowing treatment were significantly lower than those in whole season grazing?P<0.05?.?2?The abundance,biomass and genera of soil nematode communities were reduced by five seasonal rotational grazing.In comparison,the average values of nematode abundance?13264 nematodes?and biomass?230.06 ug?of two grazing treatments in spring and summer and three diversity indices of two grazing treatments in autumn were higher than those of other rotational grazing treatments.Means of Simpson dominance index and Peiluou evenness index were higher in summer and autumn grazing treatments and summer grazing treatments respectively.?3?The results of the analysis of the effect of rotational grazing on nematode functional groups showed that the abundance of functional groups was relatively high in different treatments.That is to say,the predator/omnivorous nematode functional group in T₂ treatment,Bacterial-feeding nematode and predator/omnivorous nematode in T₃,parasitic nematode in T₄,fungal-feeding nematode in T₅ and T₆.?4?Among the five seasonal rotational grazing treatments,the order of the mean value of the nutrient diversity index of nematode community was T₃>T₅>T₆>T₂>T₄.That is to say,the diversity of soil nematode feeding habits in two grazing treatments?T₃?in summer and autumn was relatively high.?5?The results of the maturity index of soil nematode community showed that the maturity index of nematode community in two grazing cycles?T₂?in spring and summer was significantly higher than that in the other four grazing cycles?T₃,T₄,T₅and T₆ were 2.27,2.17,2.18 and 2.16,respectively??P<0.05?.That is to say,the soil environment of T₂ treatment is relatively stable.In summary,the effects of whole season grazing on soil nematode community abundance,genera number and diversity were slighter than that of mowing management.Different rotational grazing treatments were beneficial to different community indices of soil nematodes;overall,T₂ had less negative impact on the abundance,biomass,diversity and maturity indices of soil nematode communities;T₃treatment was more beneficial to the stability of soil nematode community functional groups,litter layer and soil layer habitats,and nutritional diversity indices.It can be concluded that the suitable rotation grazing patterns for soil nematodes in typical grasslands of Inner Mongolia are 2 grazing times in spring and summer?T₂?,2grazing times in summer and 2 grazing times in autumn?T₃?.