[Multi-scale and multi-parameter spatial distribution patterns of Seriphidium terrae-albae and Artemisia songarica populations in Gurbantunggut Desert of Northeast China].[Pubmed: 24564127]

The researches on the plant population spatial pattern were mostly based on 0-D plant point (0-D IND) or 0-D plant count, and only a few was based on the 2-D projective cover (2-D PC) and 3-D aboveground biomass (3-D AGB reflected by canopy volume). Until now, the plant population spatial distribution patterns incarnated by these parameters were still unclear. Taking the widely distributed small semi-shrubs Seriphidium terrae-albae and Artemisia songarica in Gurbantunggut Desert of Northwest China as test objects, this paper studied the IND, PC, and AGB of each individual at two sampling plots. Through six-scale division of plot coordinate system with GIS, and by using aggregation analysis, coefficient of variation (CV) , and a scaling exponent between the CV and six scales, the characteristics of the population spatial distribution patterns with the above mentioned parameters were comparatively analyzed. At all scales, the IND (except for the S. terrae-albae population at 0.5 m scale) and the AGB of the two shrubs all presented a clumped distribution, and the aggregation intensity increased' with increasing scale. However, the PC had a uniform distribution (except for the A. songarica population at 5 and 8 m scales). With increasing scale, the CV values of the two shrubs decreased. The absolute value of scaling exponent (k value) of the IND was higher than those of the PC and AGB, and there was no significant difference in the k values between the PC and AGB, indicating that the scale variation scope of the struc- tural complexity of the IND was larger than that of the PC and AGB. The k value of each parameter for S. terrae-albae was higher than that for A. songarica, which could be related to the populations' interspecific relationship and plant size. In sum, the IND and AGB had similar spatial patterns, while the PC and AGB had almost same spatial pattern complexity and scale change characteristics.

Similarity and difference in vegetation structure of three desert shrub communities under the same temperate climate but with different microhabitats.[Pubmed: 28510895]

Community structure and species composition are closely related to plant diversity and ecosystem stability. To explore the similarity in vegetation structure of shrub communities under the same temperate climate but with different microhabitats, 36, 28 and 13 sampling plots in Ephedra distachya, Seriphidium terrae-albae and Artemisia songarica communities were selected respectively, during the course of three seasons (early spring, summer, autumn) in Gurbantunggut Desert, north-western China. The species composition, abundance, biomass and soil nutrients were investigated. Floristic changes were characterized by similarity and ordination methods.

Plant traits with different dimensions of shrubs represent different spatial patterns and plant-to-plant interactions in a temperate desert.[Pubmed: 26600733]

Projective cover (PC) and aboveground biomass (AGB) are the key traits with space attributes of individual plants. They are crucial to the understanding of the plant dynamics and plant patterns at population level. Spatial patterns based on individual plant positions (IND) have been extensively investigated in previous studies. However, very few have focused on PC and AGB. We tested the hypothesis that different plant traits represent different spatial patterns and plant-to-plant interactions. Two 40 m × 40 m plots of two typical desert shrub populations (Seriphidium terrae-albae and Artemisia songarica) were surveyed in the Gurbantunggut Desert of north-western China. Each plot was divided into a series of subplots (grids) at different scales (17 scales from 0.5 m to 20 m) using GIS (geographic information system). The spatial patterns of IND, PC and AGB were determined using aggregation and information dimension analyses together with changes in the scales. The IND and AGB of the two populations exhibited clumped tendencies at all scales (except at the 0.5 m scale for S. terrae-albae), whereas PC showed uniform distribution patterns at the moderate and small scales, (0.5 m to 8.0 m for S. terrae-albae and 0.5 m to 4.0 m for A. songarica), indicating that crown-to-crown competition for sunlight was strong at these scales. Although IND had a slightly higher coefficient of variation at the small scales, its information dimension was smaller than those of PC and AGB, indicating that PC and AGB had higher spatial complexities. In conclusion, the three parameters represented different spatial patterns across multiple scales; PC and AGB showed strong spatial complexities and PC was also an accurate indicator of plant-to-plant competition.

[Studies on the flavonoids from whole herbs of Seriphidium terrae-albae].[Pubmed: 17048665]

To investigate the chemical constituents of whole herbs of Seriphidium terrae-albae.