Study On Succession Rules And Community Stability Of Poa Pratensis L.cv.Qinghai Cultivated Grassland

The new varieties of wild forage-Poa pratensis L.cv.Qinghai successfuldomestication and breeding was used for treatment degraded grassland in the sourceregion of Three Rivers. It was important that the succession rules and communitystability of Poa pratensis L.cv.Qinghai cultivated grassland are useful for "black soiltype" degraded grassland vegetation recovery in alpine region and the stability ofcultivated grassland in alpine meadow. In the source region of Three Rivers, thesurvey continued2years time(2010-2011), selected1age to4age,10age and11agePoa pratensis L.cv.Qinghai cultivated grasslands as research object, non-degradednatural grassland and severely degraded grassland as control, the plant communitystructure, diversity, biomass, soil properties, seed yield and quality characters ofgrasslands were studied by on field investigation and laboratory experiments, thesuccession tendency and community stability of cultivated grasslands were discussed,the results are as follows:1. Along the succession procession, the Poa pratensisL.cv.Qinghai cultivatedgrassland community changes gradually stabilized, grassland ecological-stability andproduction-stability were well maintained, It indicted that the measures of use PoapratensisL.cv.Qinghai cultivated grassland restoration "black soil type" degradedgrassland in the source region of Three Rivers were feasible.2. The important succession rules of Poa pratensisL.cv.Qinghai cultivated grasslandare as follows: the changes of grassland species composition and number is relativelystable, the important values of Poa pratensis L.cv.Qinghai presented a low-high-low change trend, the differences of diversity index in cultivated grasslands weresignificant(P<0.05);2age Poa pratensisL.cv.Qinghai cultivated grassland totalcoverage, the dominant species coverage and plant height were highest, with thecontinuous succession of the communities, the total coverage, dominant speciescoverage and plant height were downward trend, but in the end these changed tostabililize; The total above-ground biomass and the dominant species of Poa pratensisL.cv.Qinghai above-ground biomass showed the trend of increased first andthen decreased, with the succession of cultivated grassland, total above-groundbiomass and bluegrass and dominant species of Poa pratensisL.cv.Qinghaiabove-ground biomass were not significant with non-degraded grassland; Theunder-ground biomass of cultivated grassland are mainly distributed in the depth of0~10cm;The ratio of under-ground and above-ground changed from7.92to13.98,and gradually close to the non-degraded natural grassland. With the cultivatedgrassland succession, soil moisture increased, soil bulk density declined, soil physicalproperties significantly improved; Soil pH value was alkaline, the content of soilorganic matter, total nitrogen, available nitrogen, total phosphorus and availablephosphorus all showed low-high-low trend；With the cultivated grasslandsuccession, seed yield and quality characters showed a downward trend.3. Comprehensive evaluation on stability of Poa pratensisL.cv.Qinghai cultivatedgrassland community: cultivated grassland community composition, diversity,community structure characters, and biomass dynamic changes basically stabilized,this results showed that community ecology-stability and production-stabilityrelatively increased; Poa pratensisL.cv.Qinghai cultivated grassland soil physicalproperties obviously improved, soil nutrient content changes also showed a certainamount of regularity, and soil properties generally tended to develop in a positivedirection, Seed yield and quality traits in decline, the dynamic changes of soilproperties and seed yield and quality adapted to community succession, the wholechanges to stabilize.