Spatial Pattern Of Artemisia Ordosica Population In Mu Us Sandland, In Inner Mongolia

As one of the four huge sandlands in china, Mu Us sandland is in the ecotone betweensemi-arid and sub-humid zone in northern China. Due to climate and human disturbancefactors, some problem came out, such as fixed dunes activation, pasture decline in productvity,biodiversity loss and degradation of agriculture lands. The desertification developed rapidly inMu Us sandland.Artemisia ordosica was desert plant, which distributed in warm temperate drygrassland and desert steppe belt, born in the fixed sandy soil and overlying sand, and it wasconstructive species and excellent sand-fixation plants in steppe sandy shrub communities.Based on field survey and remote sensing data, spatial distribution pattern of the Artemisiaordosica population and its components in Mu Us sandland was studied with the methods aspoint pattern analysis,geostatistics,multivatiate statistics, and block variance. Results showed:(1) In the scope of small-scale domain, with the improvement of the sandy habitats,Artemisia ordosica population density gradually became larger, and the crown showed adecreasing trend, so was its extent of spatial heterogeneity. With the increasing of intervaldistance, the extent of spatial autocorrelation of Artemisia ordosica population decreasedrapidly, and it showed high extent of spatial autocorrelation in the scale of0.6m. With theincrease of Artemisia ordosica coverage, the extent of spatial autocorrelation weakened morerapidly. With the interval distance, and extent of spatial heterogeneity increased more rapidly,while the range of semi-variance model of Artemisia ordosica population significantly reduced.As the coverage of Artemisia ordosica population <30%, there was2-3patch differentiation,while the differentiation occured in the scale of2-2.5m in individual level,6m in small grouplevel, and11-15.5m in large group level. As the coverage of Artemisia ordosica population>35%, there was2-3patch differentiation, while the differentiation occured in the scale of1-1.5m,4m in the small group level, and7.5-15.5m in large group level. The differentiation extent of individual level was higher than group level. The block scale of differentiation waslarger in individual level when the coverage of Artemisia ordosica population was smaller.(2) Spatial pattern of Artemisia ordosica populations in mesoscale domain divided intothree types, first the rise style, second wave style, and third for the smooth style. Spatialautocorrelation range of Artemisia ordosica populations was large in the plots of rise style.Spatial heterogeneity of Artemisia ordosica populations increased more slowly with theincrease of scale, and the phenomenon of patch differentiation just occured in large block scale,while the spatial pattern of sandy landscape showed the similar characteristics. Thesemivariance function of Artemisia ordosica populations of wave style had relatively smallerranges and the larger fractal dimension, while its spatial heterogeneity showed wave-likecharacteristics with increasing scale, and the wave function curve became stabilized gradually.Artemisia ordosica populations pattern showed significant level distributioncharacteristics. Artemisia ordosica populations had patch differentiation in various block scales,and the differentiation extent in intermediate block scale was small. The rang and fractaldimension of semi-variance function in smooth style plots was between the rise andwave-style,and it had a high goodness of fit, its semi-variance function curve was relativelystable. The phenomenon of patch differentiation occured in intermediate block scale. Spatialpattern of the sandy landscape had the similar characteristics as Artemisia ordosica populationsand sandy landscape in mesoscale domain was rise style–wave style–smooth style.(3) The fowering Artemisia ordosica showed non-aggregeted distribution in small scalesand aggregated. Distribution in large scales. The extent of aggregation decreased graduallywith increasing scale and tends to be random distribution. The non-flowering Artemisiaordosica showed aggregated distribution in small scales and tend to be randomly distributed asthe scales>6m. The L(r) function of dead Artemisia ordosica showed non-aggregateddistribution in small scales and aggregated or random distribution in large scales. The g(r)function of dead Artemisia ordosica showed aggregated distribution in small scales andrandom distribution in large scales. With the improvement of the sandy environment, spatial point pattern of floweringArtemisia ordosica turned from random distribution into uniform distribution in the small scale,while the extent of aggregated distribution decreased gratually, with a trend into randomdistribution. With the improvement of the sandy enviroment, the L(r) function showed that theextent of aggregation of non-flowering Artemisia ordosica firstly increased and thendecareased. The g(r) function showed that spatial point pattern of non-flowering Artemisiaordosica turned from random distribution into aggregated distribution and then randomdistribution. Dead Artemisia ordosica experienced the process of aggregation–random–aggregation. The spatial point pattern of living Artemisia ordosica was as similar as floweringArtemisia ordosica.