| To research Hongyuan area to siberian wildrye for advantage species grass of plant communities of main number features characteristics and the soil physical characteristics on different grazing strength of response, used four a grazing strength:controlled CK(buckle cage),and Light grazing LG(foraging rate 50%),and in the Moderate grazing MG(foraging rate 70%) and Heavy degrees grazing HG (foraging rate 90%),in plant growth quarter for classified district rotational grazing test. On plant communities species rich degrees cover degrees, height, plant community diversity, uniform degrees, community ground now stock, underground biomass volume; plant communities ground underground part soluble carbohydrates content, community photosynthesis CO2 and H2O of net pass volume changes; soil firming degrees, and capacity heavy, and moisture of research and analysis, reveals has different grazing pressure siberian wildrye straw to community features and soil of changes features and law, for the area of agricultural production provides reference data. Results of the study are shown as follows:1 Effects of different grazing intensities on community characteristics1.1 Community species richness, the height, the coverage is reduced as grazing intensity increases. The average of community species characterized by LG(12.87)>CK(1.55)>MG(10.21)>HG(8.45), and CK has no significant difference between LG and MG(P>0.05),HG has difference(P<0.05); CK>LG>MG>HG, with light grazing with control of no significant difference(P>0.05).From month, these indicators are rising in August and reach the maximum value, then decrease;1.2 Uniformity of diversity index for first increasing and then decreasing trends, through the characteristics of LG(1.4178)>CK(1.2333)>MG(1.0849)>HG(0.7879),CK and LG differ significa ntly(P<0.05), and MG and HG have no significant difference(P>0.05).1.3 Each month CK above ground biomass was significantly higher than that of the grazing areas, significant difference(P<0.05), LG was significantly higher than that of MG and HG, si gnificant difference(P<0.05), the maximum in August, which are CK(0.3792Kg/m2), LG (0.33 26Kg/m2), MG (0.258 1Kg/m2),HG(0.1853Kg/m2).The underground biomass in the0-30cmcha nge is mainly reflected in the 0-10cm depth, the depth of the underground biomass mainly con centrated amount of 0-30cm,the distribution characteristics of CK(0.0134g/cm3)>LG(0.0099g/ cm3)>MG(0.0079g/cm3)>HG(0.0067g/cm3), and CK differences among grazing treatments sign ificantly(P<0.05), grazing only LG and HG showed significant difference(P<0.05), undergroun d biomass and each treatment was maximum in September. In the 10-20,20-30cm depth, und erground biomass CK greater than 3 grazing areas, significant difference(P<0.05), values were 0.0059g/cm3,0.004 lg/cm3, no significant difference between various grazing plot(P>0.05).1.4 Several plants in soluble carbohydrate change with time and the content increased, reache d the maximum in August, then tend to be stable. Among the different treatments showed on CK(374.5325ug/g)>LG(334.1525ug/g)>MG(258.1525ug/g)>HG(225.9700ug/g),the undergroun d part of CK(285.3700ug/g)>LG(248.5733ug/g)>MG(199.2500ug/g)>HG(194.7933ug/g),CK an d LG difference was not significant(P>0.05), and in August 7, the increase was more apparen t. MG and HG are significantly different than CK(P<0.05), the content is relatively low. The underground part of soluble carbohydrate in July decreased, and then increased with time, hea vy grazing did not reflect this change.1.5 Characteristics of CO2 flux in each experimental group increased first and then decrease d, and reached the peak in August, as CK(133.42umol/m2·2)>LG(117.31umol/m2·s)>MG (88.7 8umol/m2·s)>MG(77.08umol/m2·s), significant differences(P<0.05), with the increase of grazin g intensity, flux decline. In the trend of H2O flux in severe area, the other three areas are pres ented for flux decreased first and then increased and then decreased, but not significantly he avy grazing changes, the overall trend stationary.2 Effect of different grazing intensity on soil physical properties0-10cm depth of CK compaction in July(61.05±1.02Psi), June(57.65±1.75Psi), August(69.85 ±1.11Psi), September(71.03±1.03Psi), October(93.3±2.66Psi) is much lower than the other thr ee grazing intensity of compactness, significant difference(P<0.05),July is because the entire month less rainfall and temperature is relatively higher, and the difference was not significa nt(P>0.05).10-20,20-30cm depth and two most of the performance of no significant differe nce(P>0.05),soil compaction are generally with the increase of grazing intensity and showed increasing trend, trend of bulk density and compaction are similar, increases with the increa se of grazing intensety, the control group 0-10cm depth soil bulk density each month were 1 ower than that of grazing group, there were significant differences(P<0.05), and the change s of 10-20 and 20-30cm depth is not obvious, the difference was not significant betweengr azing group(P>0.05). CK soil water content than other grazing group, July CK moisture cont ent was significantly higher than that of the other three grazing intensity area(P<0.05), bu t between each test area variation is not obvious. |
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