Factors influencing dominance structure of common rodent species in Vietnamese tropical forests

It has been shown that the balance between the common rat species belonging to the genera Maxomys and Niviventer in Vietnam regularly changes depending on the geographical latitude. The highest total rate of the genus Niviventer rats (82% of the total catch) has been observed in the northern region (22°0′N) in the Fansipan highland forests (1800–2000 m above the sea level) and has gradually decreased southward to its minimal value (1% of the total catch) in the lowland dipterocarp forests of Ma Da (11°10′N). On the contrary, Ma Da, the southernmost point, displays the highest rate of Maxomys rats, which decreases northward, reaching less than 2% in the Fansipan forests. The ecological advantages of these common genera are associated with the specific features of their origin and establishment. A case study of a particular area, the Cat Tien National Park, has demonstrated the effects of forest structure and the degree of its disturbance in the balance between the three dominant species, namely, the rats Maxomys surifer and Niviventer fulvescens and the squirrel Callosciurus flavimanus. An additional factor that influences the populations of the rats in question in local areas is their interspecific interactions with the rats of the genus Rattus.