Structure And Dynamics Of Reaumuria Soongorica Population In Different Habitats

Reaumuria soongorica（Pall.）Maxim, the most widespread shrub type in thedesert region. It is an important biological barrier for protecting desertification landwith strong stress resistance, more ecological plasticity, strong drought resistance,salt tolerance and sand setting. According to the natural distribution of R. soongoricain Gansu province, we selected three typical distribution areas (Zhangye, Wuwei,Lanzhou, where the mainly constructive plant species of R.soongorica) from east towest as the objected area. Field survey was carried on R. soongorica population indifferent habitats. The age structure, survival curve, spatial distribution pattern of thepopulation were studied and analyzed, the static life table were determined, thepopulation age class structure were simulated and predicted by single movingaverage of time sequence analysis, and the population dynamics were also describedquantitatively. Base on all the analyses mentioned above, we put forward somemeasures for the conservation of this species. Theoretical basis were provided for theeffective protection and rational utilization of this species. The results showed that：1) The age structure of the three populations was very similar, the plants weredistributed in every age class level and almost distributed in the middle age-class;The age structure of three populations was basically a bell-shaped one, showed thatthese three populations were stabilized. Zhangye R. soongorica population numbersbegan declined sharply after4years later and stepped in senescence; Wuwei andLanzhou R. soongorica populations’ quantity began reducing in their7years andbegan coming to the period of decline.2) Zhangye R. soongorica population’s survival curve mainly belonged toDeevey Ⅱ type, theirdeath rate closed to each ages and the population was stable.Wuwei and Lanzhou R. soongorica populations’ survival curve mainly belonged toDeeveyⅠ type, It’s showed that the R. soongorica populations had a lower earlydeath and the population quantity growing faster, Over time in figure showedsurvivals began significantly reducing in7years and start to decrease, at last it reached to a stable state, this result as same as static life table, reflected thepopulations are increase types.3) Next2to4years later, Zhangye R. soongorica population will showedgrowth trend, But4years later its growth will slowed. Wuwei R. soongoricapopulation’s growth rate faster than Zhangye R. soongorica population, each ageamount will be increased and grow quickly4years later. Lanzhou R. soongoricapopulation had the quickest growth rate, in the early time has a faster growth rate.But with growth and time passed by, the growth rate will become reduced; thepopulation is tending towards stability.4) Zhangye R. soongorica population is in a state of growth, the population’sgrowth rate between1and2year was the most remarkable. Wuwei R. soongoricapopulation’s dynamic variation index is0.21, indicated that the population is actuallygrowing; Lanzhou R. soongorica population has the biggest dynamic variationindex(0.92),From the first age in a Long-term growth trends until8years,thengoing to be maximized.5) These three R. soongorica populations’ spatial pattern were aggregateddistribution and they had different aggregation extent, the aggregation degree ofthese three R.soongorica populations were in the order Wuwei R.soongoricapopulation(3.3142)> Zhangye R. soongorica population(2.9835)> Lanzhou R.soongorica population(2.8760). In the same population, aggregating intensity wasdistinct during different growth periods, which manifested the young stand had themaximum level of aggregation, closely followed by aging population andMiddle-aged had the smallest intensity index.