Abstract: The traditional point pattern analysis based on species mapped points has its limitation when the plant individual difference is very large or the scale of the interest is of the same order of magnitude as the size of plant individual. This paper introduced a grid-based approach, extending point pattern analysis, to analyze the spatial distribution pattern and ecological process of some objects with special shape and area. Taking the spatial pattern of endemic Tetraena mongolica population with narrow area distribution in west Erdos of Inner Mongolia as a case, a community block of 30 m × 30 m was randomly selected, and divided into 1600 sub-blocks of 75 cm × 75 cm. All the photos of the study site were obtained by photography orientation method, and then processed and digitized by image processing software and GIS software. All the analyses were done by the software Programita. By using the extending point pattern analysis to analyze the spatial pattern of T. mongolica and its relationships with Zygophyllum xanthoxylum in the community, it was shown that there was a uniform distribution for the T. mongolica population at a scale of 69-99 cm, and a negative correlation betweenT. mongolica  and Z. xanthoxylum at a scale of 350-570 cm. The grid-based method was a better way to understand the spatial pattern of shrub population.

Key words: Petrophytia moss, Forest vegetation, Disturbance, Water and soil conservation