SINGAPORE – For years, scientists had thought that the loss of nearly all of Singapore’s original forests over the past two centuries had wiped out about two-thirds of its biodiversity.
Following the founding of modern Singapore in 1819, swathes of lush forest and its natural inhabitants were cleared to make way for people, plantations, and buildings.
But a recent report has revealed that 37 per cent of the city-state’s flora and fauna species had vanished during this period of deforestation and urbanisation. While it is a significant amount, it is less than previously estimated. In fact, it is nearly half of the estimated extinction rate of 73 per cent in a well-cited 2003 paper.
The latest study involving 27 experts and junior researchers, which used novel mathematical models, was published in scientific journal PNAS in December 2023.
Notably, the decade-long research led by theoretical ecologist Ryan Chisholm from the National University of Singapore (NUS) developed statistical methods that accounted for dark extinctions – the unknown number of plants and animals that died out before they were discovered.
Globally, these silent extinctions have posed a problem for scientists looking to chart the true scale of human-driven extinction.
“The findings are significant for Singapore,” said Associate Professor Chisholm, who conceived the research idea in 2012.
“(The study) gives more accurate estimates of extinctions than past studies, and it identifies large and charismatic species as having been particularly vulnerable to extinction here.”
Charismatic species are fauna and flora that garner more public interest due to their aesthetic appeal or cultural significance. In the Singapore context, examples of these species include pangolins and orchids, said Prof Chisholm.
Historic records for flora and fauna groups here that are not as well-studied can be too sparse, making it difficult to figure out just how many species once existed on the island.
Dr Tan Heok Hui, fish curator at NUS’ natural history museum, who co-authored the recent paper, said much of the original freshwater fish on the island was likely to have been unrecorded as the earliest checklist dates back to the 1960s, almost two decades after large tracts of mangrove and freshwater forests had been cleared.
He said: “The freshwater fish records may not be complete, but nonetheless provide a vital clue to past events.”
To paint the most accurate picture of extinctions in Singapore, the researchers painstakingly assembled a comprehensive database of records, comprising more than 50,600 observations of over 3,060 species from 10 major animal and plant groups.
The library ranges from the oldest natural history material obtained in Singapore – a sea teak stalk collected in 1796 – to social media sightings and citizen records, like a photo taken by Prime Minister Lee Hsien Loong of a black-headed collared snake, which is a vulnerable species here.