Effects Of Grazing Animal Type And Intensity On The Typical Steppe Ecosystem In Inner Mongolia–Preliminary Results From An Experimental Research

Grazing is an important way for utilization and management of grassland ecosystems.In order to understand the effects of grazing animal types and grazing intensity on the grassland ecosystems,we conducted two experimental research on the effects of four sheep grazing intensities?light,moderate and heavy grazing,and no-grazing control in Experiment and moderate grazing of three animal types?sheep,goat,cattle and no-grzing control in Experiment on the plant community structure and production,soil properties and fertility,and animal production performance,as well as their interactions.The main results are as follows:1?Grazing had a significant effect on soil physical properties in top soil layers?0-10 cm?.With the increase of grazing intensity,soil bulk density increased,moisture content declined,TOC content decreased.Moderate grazing of sheep or goat significantly decreased soil bulk density and moisture content,and moderate grazing of goat and cattle also decreased soil TOC.Grazing had no significant effects on soil pH.2?At the same moderate grazing intensity during the summer and autumn period?June-August?,the average daily forage intake of cattle was 9.03 kg·head^-1;Cattle prefered to graze Stipa grandis,Carex korshinskyi and some non-dominant forbs,but not Leymus chinensis and Cleistogenes squarrosa.The average daily forage intake of sheep was1.79 kg·head^-1;Sheep prefered to graze Leymus chinensis,Carex korshibskyi and other non-dominant forage species,including forbs,but not Stipa grandis or Cleistogenes squarrosa.The average daily intake of goat was 1.71 kg·head^-11 for goat;goat prefered to graze Carex korshibskyi,Cleistogenes squarrosa and other non-dominant species,inclduing forbs,but not Stipa grandis and Leymus chinensis.3)With the increase of grazing intensity,the relative biomass of perennial rhizome grasses showed no significant changes,while that of bunchgrasses declined,and that of annuals and biennials increased.Compared to fenced grassland,the relative biomass of bunchgrasses in grazed grassland decreased,and that of annuals and biennials increased,while that of rizomatious grass and forbs showed no significnat changes.4)The grassland productivity increased first and then decreased with the increase of grazing intensity.Compared with enclosured grassland,cattle grazing significantly increased?P<0.05?,while sheep orgoat grazing had no significant effect on grassland productivity.5)Plant belowground biomass in top soil layer?0-10 cm?declined with the increase of grazing intensity?over the two year period?;plant belowground biomass under moderate grazing of cattle and goats were lower than that in enclosed no-grazing grassland.No significant difference in plant belowground biomass was detected between years.6)For different animals grazing on the typical steppe of Inner Mongolia over the June-August period,the average daily bodyweight gain wass 0.15 kg per head for sheep,0.13 kg per head for goat,and 0.64kg per head for cattle.The daily bodyweight gain of sheep was correlated with daily feed intake,and declined with grazing intensity.Our research results provide new data and principles for the development of grassland management systems for both grassland resource use and ecological security.Some resultd form this study need to be verified in the continuation of this long-term grazing experiment.