Community, Ecological and Reproduction Properties of an Endangered Plant Species: Helianthemum ordosicum

摘要

Helianthemum ordosicum, Y.Z. Zhao, Z.Y. Zhu et R. Cao, is a third generation remnant endemic species found in East Alashan and the West Ordos desert of the Mongolian plateau. We studied the community ecological and reproductive properties of the H. ordosicum for 5 years; i.e. habitat, environmental adaptation, relationship with other plant communities, pollination, seed formation, and sprouting. The study was based on field observations, sampling, and laboratory analyses. Our results indicate that the distribution range of H. ordosicum is decreasing. The plant community has gradually adapted to dry-climate conditions, and has an old, age structure. These results indicate both the effects of environmental change and disturbances relating to human activities. Our study shows that sexual propagation was not accomplished, pollination efficiency was low, and that embryos rarely reached maturity. Vegetative reproduction is performed by stem breaking. However, seeds of H. ordosicum were readily sprouted and cultivated in the laboratory, and the sprouting rate was high. We suggest, therefore, that this method could be a means of protecting certain endangered plant species.Helianthemum ordosicum belongs to the Cistaceae (1) family, is a third generation remnant species which is also characteristic of the Mediterranean flora. It is distributed at the foot of Zhuozi mountains in the West Ordos of Inner Mongolia, China (2). The distribution range is very limited. The environment in West Ordos and the East Alashan desert is subject to severe extremes (3). The climate ranges from very cold in winter to very hot in summer. The area is also windy, and has only very slight precipitation 200-252 mm yr~(-1) (4). The evaporation level is 3000 mm yr~(-1). The soil in the region is brown calcium or sandy soil, which is prone to serious erosion.