Effect Of Mowing On Community Characteristics And Forage Yield And Quality In Stipa Grandis Steppe

Mowing is one of the most common way of grasslands utilization.However,plant growth and reproduction,grassland productivity and species diversity are effected to a certain extent by aboveground removing.Consequently,the grassland ecosystem sustainability is negatively impacted.As a traditional utilization way of Stipa gradis typical steppe,haymaking plays an important role in providing adequate forage in spring and winter to maintain animal husbandry production.Thereby mowing properly is beneficial to grassland healthy and sustainability.A two-factor randomized block experiment was designed in 2014,and consecutively been carried out in 2015-2016 with different mowing date,including mowing in 1 st-August,16th-August,and 31 st-August,and different intensity,including 2cm-stubbed height,5cm-stubbed height,8cm-stubbed height and no mown as control(CK).Through the evaluation of mowing date and mowing intensity effects on grassland community characteristics,species diversity,and forage yield and quality,to determine the optimal mowing patterns.The main results are as follows:1.Aboveground net primary productivity of community and perennial bunch grass decreased under mowing(p<0.05),while perennial forbs and annual and biennial herbs'aboveground net primary productivity increased(p<0.05).The proportion of grass increased and forbs decreased with the delay of mowing date and the increase of mowing intensity(p<0.05).2.The root shoot ratio was also increased(p<0.05)as mowing intensity increasing.Above-below ground biomass trade-off tended to weight more on aboveground in the higher precipitation year,while an opposite tendency in the lower precipitation year.Nonetheless,plant trade-off can be converted from weighting on aboveground to belowground with the increase of mowing intensity.3.Species richness increased with the increasing of mowing intensity(p<0.05),the higher of community species richness was due to the improvement of species richness of annual and biennial herbs.4.Forage yield increased in the higher precipitation year but decreased in the lower precipitation year with the delay of mowing date(p<0.05).Forage crude protein decreased with the delay of mowing date and increasing mowing intensity(p<0.05).Taking grassland productivity,species diversity,forage yield and quality into consideration,we can simply draw a conclusion that the optimal mowing date in S.gradis typical steppe is on late August in the higher precipitation year,and on mid-August in the lower precipitation year,with the stubble height of 5-8 cm in short-term mowing study.