Volume Fractal Dimension of Soil Particles and Relationships with Soil Physical-Chemical Properties and Plant Species Diversity in Bayinbuluk Alpine Grassland

Fractal geometry is an important method in soil science, and many studies have used fractal theory to examine soil properties and the relationships with other eco-environmental factors. However, there have been few studies examining soil particle volume fractal dimension in alpine grasslands.

Bayinbuluk grassland is one of the largest alpine grasslands in China, and it has a special significance for the ecological conservation in Xinjiang. In the recent years, the grassland has degraded seriously due to some disturbance factors such as overgrazing, mowing, use of pesticides for the control of mice and insects, and the development of tourism. As a result, researchers have paid an increasing attention to environmental problems in this grassland. There are quite many investigations to the alpine vegetation, but few studies address the volume fractal dimension of soil particles (D) in this region.

To study the D and its relationships with soil salt, soil nutrient and plant species diversity, we conducted an experiment on an alpine grassland under different disturbance degrees: non-disturbance (N₀), light disturbance (L), moderate disturbance (M) and heavy disturbance (H).

The results showed that Ds varied from 2.573 to 2.635 among the different disturbance degrees and increased with increasing degrees of disturbance. Shannon-Wiener diversity index, Pielou’s evenness index and Margalef richness index reached their highest values at the M degree, indicating that moderate disturbance is beneficial to the increase of plant species diversity. In the L and M degrees, there was a significant positive correlation between D and clay content and a significant negative correlation between D and soil organic matter (SOM). In the H degree, D was significantly and positively correlated with total salt (TS). The results suggested that to a certain extent, D can be used to characterize the uniformity of soil texture in addition to soil fertility characteristics. For the L degree, there was a significant negative correlation between D and the Shannon-Wiener diversity index; while for the M degree, there was a significant negative correlation between D and Pielou’s evenness index.

The study was published in Journal of Arid Land in December 2013.