The ‘peak-cluster landscape’ is the most common type of karst landscape in southwest China, which has very shallow soils and a high degree of bedrock exposure. On karst mountain peaks, the soils can be readily saturated by rainfall and then rapidly dried by solarization. Therefore, the soil habitat on karst mountain peaks may differ from that of other soil habitats in the karst peak cluster landscape and climatic zones. Nematodes are the most abundant metazoa on the Earth. However, information on the composition of soil nematode communities on karst mountain peaks is lacking. 

Nematodes are ubiquitous in soil and are assigned to main trophic groups (bacterivores, fungivores, herbivores, omnivores, and predators) and functional guilds. Rhabdolaimus is generally rare in terrestrial ecosystems but is common in aquatic ecosystems. The arising question is that how does a common aquatic nematode dominate a relatively arid terrestrial soil habitat? 

Researchers from the Institute of Subtropical Agriculture, Chinese Academy of Sciences (ISA) determined the composition of soil nematode communities along a vegetation succession sere on karst mountain peaks in the wet and dry seasons, at karst Huanjiang Observation Research Station for Karst Ecosystems in Guangxi. They divided four common plant communities into moss crust, moss crust with sparse grasses, sparse grasses and sparse dwarf shrubs. 

"The nematode communities were unusual, and Rhabdolaimus was the most abundant nematode genus, and Aphelenchoides and Acrobeloides were the sub-dominate genera."said leader researcher ZHAO Jie from ISA. The team also found that Rhabdolaimus is a common aquatic nematode genus that has been detected in hot springs but has not been previously reported as the dominant genus in relatively arid and semi-arid soils. "Therefore, tolerance to extremely high soil temperatures and rapid wet- dry cycles may help explain why Rhabdolaimus dominates the nematode communities in the soils of karst mountain peaks in southwest China."

Besides, different plant community compositions are general correlated with different soil conditions (soil organic matter, total nitrogen content, moisture, temperature, pH, etc.), which also affect soil nematodes. 

This research was supported by the Chinese Academy of Sciences Action Plan for the Development of Western China (KZCX2-XB3-10) and the program of the Youth Innovation Promotion Association of Chinese Academy of Sciences (2015303). 

The study entitled “Unusual soil nematode communities on karst mountain peaks in southwest China” has been published in the Volume 88, 2015 of Soil Biology & Biochemistry, details could be found at http://www.sciencedirect.com/science/article/pii/S0038071715002254.