Recovery of a rodent community in an agro‐ecosystem after flooding

Abstract

The Dongting Lake region is one of the areas prone to flood disaster in China. Despite the frequent occurrence of flooding in this area, few studies have analysed its effects on rodent communities, especially their recovery after withdrawal of floodwaters. We carried out a study of rodent recovery after flooding of the Dongting Lake region in 1998. Rodent population monitoring in the flooded countryside of the Dongting Lake region was conducted during 1998-2001. The census was conducted in Anzao polder of Anxian County in Hunan Province, where the dike burst in 1998 and thousands of hectares of farmland were flooded from July to October. The results indicate that flood disaster could provide important changes in rodent community structure. Firstly, species abundance in the post-flood area became less than in the normal area. Striped field mice Apodemus agrarius colonized the flooded area in farmland until March 2000, and Norway rats Rattus norvegicus and house mice Mus musculus occurred in July and December 2000, respectively. The degree of the effect on the rodent community in residential premises is less than that in farmland. However, the rodent community in the flooded area could recover and become similar to the normal community. The recovery of rodent species composition was faster in residential premises than in farmland after flooding. Secondly, there was a similar tendency of the dominant concentration indices between post-flood and normal areas. Thirdly, inundation for a long period could reduce the species diversity of the rodent community in farmland. The significant difference in abundance was continued to 2000 in postflooded farmland; however, the influence on the rodent community in residential premises was less and their diversity indices did not differ in 1999. Similarity indices indicated that variation between post-flood and normal areas had been gradually becoming low from 1999 to 2001. Finally, the monitoring data showed that rodent populations in the flooded area were less than those in the normal area in the first step after withdrawal of floodwaters. However, the rodent population increased rapidly in the flooded area, and became greater than that in the unflooded area in half a year. The population in the flooded area also increased faster than that in unflooded neighbouring area after the application of rodenticide. Another phenomenon was that the population density of rodents could reach levels greater than the normal area, and may continue for more than 2 years. Flood disasters could reduce population densities and species abundance, species diversity and evenness, while increasing dominant concentration indices of the rodent community. However, after 3 years, the rodent community structure became similar to that in the non-flooded area, except for high density. The recovery of rodent communities in residential premises was faster than that in farmland for a lesser degree of flooding.

The influence of spring floods on small mammal communities in the Nemunas River Delta, Lithuania

“…Long duration heavy flooding has more detrimental consequences to small mammals, though this may be buffered by the presence of refuges and the mobility of organisms (Zhang et al 2007). The disruptive consequences of a flood depend on the water level, the duration of a flood and the speed of water rise (Andersen et al 2000).…”

“…Small mammals have to repopulate from adjacent sites (Ellis et al 1997), and the flood consequences on rodent communities are shortterm (Zhang et al 2007). In the case of M. oeconomus, it is known that the re-population of formerly flooded areas occurs along linear structures of the landscape, such as roads, channels and rivers (Tast 1966).…”

“…Flooding of coastal and river areas affects mammals, amphibians and plants (Berry 2009). The influence of flooding on different species may be affected by its duration and coverage, as well as by the habitat structure of the area (Zhang et al 2007). With the exclusion of arboreal species, flooding may become a lethal agent for most of the small mammals in the area (Andersen et al 2000;Zhang et al 2007) or significantly decrease their numbers (Chamberlain & Leopold 2003).…”

Effects of moisture conditions on the small mammal communities of floodplain forests in south Moravia (Czech Republic)

“…The indirect effect of floods -which is the high primary production following the floods -has positive effects on their population density (Zejda 1991). The small mammal species (Rodentia, Eulipotyphla) are well known to be responsive to the variation in moisture in terms of changes in community structure and their monitoring can therefore be of bioindicative significance (Wijnhoven et al 2005;2006;Zejda 1976;1985;Zhang et al 2007). …”

Candidate Vectors and Rodent Hosts of Venezuelan Equine Encephalitis Virus, Chiapas, 2006–2007

“…51 It has been shown that flooding can reduce both rodent abundance and species diversity for up to 2 years after a farmland-flooding event. 52 With a large reduction in the number of available reservoir/amplifying hosts, virus lineages can die off resulting in transmission-focus fragmentation or elimination. Our collections, which were begun 9 months after the storm, could lack the seroprevalence found in pre-storm collections because of interruption of the natural transmission cycle.…”