Part of Holland Plain, home to orchid once thought extinct, up for conservation

SINGAPORE - A patch of scrubland in Holland Plain is slated for conservation, with the authorities planning to earmark land in the private housing precinct to protect an orchid once thought extinct in Singapore, as well as a stronghold for pitcher plants.

Holland Plain is one of two locations here formally disclosed in publications where the straggly rush orchid (Dendrobium lobbii) can be found. Critically endangered here, it was rediscovered in the forest near MacRitchie Reservoir in 2007, after going undetected for over 70 years.

Conserving the parcel, estimated to be about 0.34ha or nearly half the size of a football field, will also save a sliver of space for Singapore’s pitcher plants. The area is naturally home to all three of the Republic’s native species, two of which are locally vulnerable.

Retaining the patch – located near Clementi Forest – was among recommendations by two environmental impact assessments for the development of housing in Holland Plain and the enhancement of its road network. Both assessments were made public on Dec 12.

To balance development with conservation, the Urban Redevelopment Authority (URA) will be amending its masterplan to incorporate the scrubland, said the environmental impact assessment for the project site, which covers a quarter of the land parcels slated for housing in Holland Plain.

Part of the scrubland had been identified as an area of high conservation value by an earlier environmental study assessing the impact of the Cross Island Line on Turf City and Holland Plain.

The patch will be incorporated as a “green finger” into a future park, wedged between two residential plots, according to the report.

When ready, the new neighbourhood will comprise about 2,500 homes as well as parks and recreational spaces, the URA said on its website.

However, the recently released 260-page report by engineering consultancy AECOM warned that despite conserving this parcel, “the large loss of the scrubland habitat” will still heavily impact biodiversity.

Vegetation, including about 1.56ha of forest dominated by exotic trees and roughly 2.71ha of scrubland, is expected to be cleared.

The assessment also noted that the locally vulnerable Raffles’ pitcher plant (Nepenthes rafflesiana), recorded at the site by the Cross Island Line study, was not found during recent visits.

It recommended that access to the orchid and carnivorous plants be strictly controlled to prevent poaching by hobbyists. This could be implemented through raised boardwalks and railings.

In total, six plant species were deemed to be of conservation significance in the 14.5ha area assessed for environmental impact, with the report calling for at-risk flora to be transplanted before construction begins.

Drawing on previous studies, the report said a total of 131 animal species, including the critically endangered straw-headed bulbul and Sunda pangolin, were found within the study area, part of which was identified as a key stopover point for wildlife to rest as they travel between Singapore’s dwindling green spaces.

Separately, an environmental impact assessment commissioned by the Land Transport Authority (LTA) to redevelop Laurel Wood Avenue linked to the Holland Plain site also recommended measures to limit impact on wildlife.

The road borders the 27ha Greenleaf forest to the east of the Rail Corridor; the forest is slated for future housing.

The 106-page report prepared by consultancy Aurecon found a notable diversity of bats, logging eight out of Singapore’s 20 bat species. This included high numbers of the glossy horseshoe bat (Rhinolophus refulgens), a species typically found in major forest reserves.

These were detected during field surveys for the 106-page assessment between July 2022 and September 2022.

To limit the development’s impact, the report recommended, among other measures, installing special street lighting on the new road to minimise light pollution, which disrupts bat navigation, roosting and feeding.

Second-year environmental earth systems science undergraduate Emma Chao, who co-authored a report in NUS’ Singapore Biodiversity Records showing that glossy horseshoe bats used the Rail Corridor, called for the recommended measures to be implemented.

“Horseshoe bats have evolved a form of echolocation suited to cluttered habitat, and although the species can endure some road crossings, too much light and noise could drive them away,” said the Nanyang Technological University student, who has helped out in three bat research projects here.

“Care must be taken to thoroughly shield lights and reduce nocturnal noise, with consideration for when bats are most active.”

She noted that any loss of tree cover in the Laurel Wood Avenue site will degrade the amount of habitat for glossy horseshoe bats to feed in, as the species requires dense vegetation.

For the Holland Plain site, the clearance of forest could encroach on the sole corridor that connects the horseshoe bats to sites like Laurel Wood Avenue, said Ms Chao.

Mr Muhammad Nasry Abdul Nasir, executive director of nature group Singapore Youth Voices for Biodiversity, welcomed the conservation of the Holland Plain patch, but raised some concerns.

He was consulted for both engagements as a representative for nature groups.

He noted that insufficient data was collected for the Laurel Wood Avenue report, citing the short timeframe of the surveys and the omission of a nearby canal that could harbour wildlife.

“A survey was conducted in August, just before migratory season begins, which naturally means that only resident birds will be found in the survey,” said Mr Nasry.

He also called for a 100m-long buffer to shield a freshwater marsh in the Holland Plain neighbourhood.

Following the 2022 Cross Island Line environmental impact assessment, which earmarked the marsh for development, his group has taken residents and members of the hiking community on walks there, in the hope that the increasingly rare habitat could be saved.

The previous report had described the marsh, which likely formed more than 40 years ago, as one that supports a diverse community of dragonflies and damselflies.

While the authorities have since started the construction of a replacement habitat, dozens of new residents moving to the area could easily destroy the recreated marsh, he warned.

Without an adequate buffer, he added, the delicate ecosystem could be threatened by future residents.

“All it takes is for a resident to complain about the marsh years from now, leading to routine mosquito fogging that could wipe out dragonflies and frogs that naturally control mosquitoes,” he said.

The Holland Plain report noted that fumigation is anticipated to be infrequent with the implementation of effective measures to control mosquitoes and other pests.

The public have until Jan 8 to read and provide feedback on the Holland Plain report at this website. Those interested to give feedback on the Laurel Wood Avenue report can do so here.

To date, four environmental impact assessments have been released in December.

Correction note: In an earlier version of the story, we said the URA amended its masterplan to conserve the patch of scrubland. It has since been clarified that the masterplan will be amended.