| Natural Haloxylon, theⅢlevel protected plants in China, belongs to the Haloxylon ammodendron Bunge shrub or small tree of Chenopodiaceae which is cold and drought resistance and adapted to wind erosion and sand bury. It is is an important ecological protection barrier for northwestern China and even for the whole country's ecological security. According to the landform, physiognomy, soil moisturewat, soil salinity and artificial and other natural factors, the habitat of Ulan Buh Desert is divided into followings: hill, gentle and flat ground terrain, fixed dunes, semi-fixed and moving dunes, Wa≤1.35%,1.35% <Wa≤7.09% and Wa≥7.09%,Sa<0.44%,0.18%≤Sa<0.44% and Sa≥0.44%,closed area and grazing area. Meanwhile the paper analyzed the population characteristics of natural Haloxylon ammodendron, which is based on the system theory of species character. And fully understand the population of Haloxylon, which provided scientific basis for effective protection and utilization of the region Haloxylon. Results of this study are as follows:(1)The spatial patterns of natural Haloxylon ammodendron populationThe following habitat about the population of natural Haloxylon ammodendron which presents aggregation distribution: gentle and flat ground terrain, 1.35% <Wa≤7.09%, Sa<0.44% and 0.18%≤Sa<0.44%,closed area.The following habitat about the population of natural Haloxylon ammodendron which presents mainly uniform distribution pattern: hill, Wa≤1.35% and Wa≥7.09%,Sa≥0.44%,grazing area.(2)Quantitative characteristics of natural Haloxylon ammodendron populationThe density and coverage of natural Haloxylon ammodendron Population in the Ulan Buh Desert were larger than the ones of natural Haloxylon ammodendron Population in Kumtag Desert and Minqin; the height and ground diameter in the Ulan Buh Desert were smaller than the ones in Kumtag desert, but bigger than the ones in Minqin.Natural Haloxylon ammodendron was not significant not different between crown width and height of the Haloxylon ammodendron in a hill, gentle and flat ground terrain, ground diameter of Haloxylon ammodendron in fixed dunes, semi-fixed and moving dunes, Haloxylon ammodendron density in Wa≤1.35%, 1.35% <Wa≤7.09% and Wa≥7.09%, Haloxylon ammodendron density in Sa<0.18%, 0.18%≤Sa<0.44% and Sa≥0.44% and Haloxylon ammodendron density and coverage in closed area and the grazing area. Natural Haloxylon ammodendron was significant difference of coverage of Haloxylon ammodendron in fixed dunes, semi-fixed and moving dunes, coverage of Haloxylon ammodendron in Wa≤1.35%, 1.35% <Wa≤7.09% and Wa≥7.09% and Haloxylon ammodendron crown width, height and ground diameter in closed area and the grazing area.(3)Age structure of natural Haloxylon ammodendron populationThe age structure of Haloxylon ammodendron population belonged to increasing type.It manifested that the age structure of Haloxylon ammodendron was an increasing type in hill, gentle and flat ground terrain, fixed dunes, semi-fixed, Wa≤1.35% and 1.35% <Wa≤7.09%,Sa<0.18% and Sa≥0.44%,closed area and grazing area.It manifested that the age structure of Haloxylon ammodendron was an stable type in moving dunes, Wa≥7.09%,0.18%≤Sa<0.44%.(4)Life table and survival analysis of natural Haloxylon ammodendron PopulationThe survival curve of the natural Haloxylon ammodendron population in Ulan Buh Desert belonged to concave curve of Deevey-Ⅲtype on the whole, which presented the characteristics of prophase growth, mid-term stability and late recession.The following habitat about the survival curve of the natural Haloxylon ammodendron population belonged to concave curve of Deevey-Ⅲtype on the whole: hill, gentle and flat ground terrain, fixed dunes, semi-fixed and moving dunes, Wa≤1.35% and1.35% <Wa≤7.09%,Sa≥0.44% and Sa<0.18%,closed area and grazing area.The following habitat about the survival curve of the natural Haloxylon ammodendron population belonged to concave curve of Deevey-Ⅱtype on the whole:Wa≥7.09%,0.18%≤Sa<0.44%, the mortality probability in different age class changed little.The survival condition of Haloxylon ammodendron in Ulan Buh Desert isⅠage class of Haloxylon ammodendron seedlings,Ⅳage class of Haloxylon ammodendron which grown vigorous andⅤage class of decline Haloxylon ammodendron.The habitats of in closing region is the same as the survival condition in Ulan Buh Desert, which is the habitats of hill, gentle ,fixed dunes, semi-fixed dune, Wa≤1.35%, closed area.The survival condition of Haloxylon ammodendron in Ulan Buh Desert isⅠage class of Haloxylon ammodendron seedlings,Ⅳage class of Haloxylon ammodendron which grown vigorous andⅥage class of decline Haloxylon ammodendron. The habitats in moving dunes is the same as Wa≥7.09%,Sa<0.18% and 0.18%≤Sa<0.44%.The survival condition of Haloxylon ammodendron in grazing region was classⅠwas the seedling age, classⅢwas strong, classⅣwas decline when the habitats is the flat ground terrain, Sa≥0.44% and soil moisture 1.35%<Wa≤7.09%. The habitats in flat ground terrain is the same as 1.35% <Wa≤7.09%,Sa≥0.44%, and grazing area.(5)Fecundity table and survival forecast of natural Haloxylon ammodendron populationFrom the fecundity table and matrix model analysis of Leslie, we concluded that the average period of whole generation about natural Haloxylon ammodendron population was 9.5a in Ulan Buh Desert, which was mainly for the steady growth.It manifested that the age structure of Haloxylon ammodendron was an increasing type in hill, gentle and flat ground terrain, fixed dunes, semi-fixed dune, Wa≤1.35% and 1.35% <Wa≤7.09%,Sa<0.18% and Sa≥0.44%,closed area and grazing area.It manifested that the age structure of Haloxylon ammodendron was an stable type in moving dunes, Wa≥7.09%,0.18%≤Sa<0.44%. |
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