Near-complete extinction of native small mammal fauna from forest fragments

Background/Question/Methods

Tropical forests are becoming increasingly fragmented by ongoing deforestation patterns and the construction of roads and other structures, leading to biodiversity declines. A key question is how rapidly species disappear from forest fragments and how quickly human interventions much be taken to avoid extinctions. We surveyed small mammal communities on recently formed islands in Chiew Larn reservoir, Thailand during two time periods: 5-7 and 25-26 years following isolation. 

Results/Conclusions

We observed the near-total collapse of native small mammal communities within 5 years from <10 hectare fragments and within 25 years from 10-100 hectare fragments. Although the presence of a non-native species might have contributed to the rapid extinction rates observed in our study, species invasions are becoming increasingly common in degraded forest fragments and our results therefore remain particularly relevant and informative to other fragmented forest landscapes. Our results show that small forest fragments provide little value for biodiversity, and suggest that conservation efforts should instead focus on preserving large expanses of undisturbed forests.