Species richness and co-occurrence patterns of Galliformes in China at three large spatial scales : does scale size matter ?

Summary.— Null model analysis was used to investigate the existence of structure in the communities of Galliformes from China at three large spatial scales. The following questions were asked : (1) Are there non-random patterns in community structure of Galliformes in China at different spatial scales ? (2) If so, what are they ? (3) Are observed patterns consistent across three different yet large spatial levels ? We used species richness (i. e., the number of species) for each grid cell to test for non-random patterns of species co-occurrence at three spatial scales : 1° ×1°, 5° ×5° and 10° ×10° respectively. We compiled matrices with presence / absence information of 51 species of Galliformes occurring in China, in which each species represents a row and each site a column. We used the C-score as a quantitative co-occurrence index, and pseudo-community analysis was performed with 30 000 Monte Carlo simulations to contrast real data with random data. Our study shows that the regions of highest species richness are situated in the SW China-Yunan and Sichuan Provinces. Species co-occurrence pattern was in part scale-dependent, with non-random co-occurrence patterns emerging at the two smaller spatial scales. Co-occurrence analysis of guilds (based on diet and habitat types) suggested that species assemblage is random for most of the null models at three spatial levels. Overall, our results indicate that interspecific competition could not be sufficient to explain the species randomness pattern of Galliformes species.