I had so much fun at the Singapore Botanic Gardens field trip on the 5th of February 2022! That is a com-peat (‘complete’) understatement to describe my joy in discovering the stark and unusual world of flora that thrives in the acidic soils of the swampy forest. Whenever I think of freshwater swamp forest (FWSF), I am reminded of the last remaining patch of primary FWSF, the Nee Soon Swamp Forest (NSSF) which occupies a mere 0.87 km2 and home to many endemic species such as the Reticulated Swamp Crab, (Parathelphusa reticulata) and the recently discovered Singapore Firefly, Luciola singapura.  FWSF used to occupy 16% of primeval Singapore’s land but today, it is occupies only a minuscule 0.39%. FWSF are well-known for their environmental benefits in peat accumulation and as carbon sink. Regionally, they have been cleared and used for their rich, fertile soil to grow oil palms plantations. It takes millenniums for peat to form in wetlands conditions. It’s a shame that in the past century, vast areas of FWSF have been cleared for development or drained for oil palm plantations. The field trip, however, has invigorated me with hope in conservation and restoration knowing that there are other FWSF in Singapore! To swamp you with the joy of conservation, the Gardens by the Bay has announced a new freshwater wetland too!

My map of the Keppel Discovery Wetlands at the Singapore Botanic Gardens (Ophelia Ong)

On our walk around the Keppel Discovery Wetlands guided by Prof Gretchen, I was treated to an orchestra of the calls of the lineated barbet, yellow-vented bulbuls and crickets. I occasionally pulled down my mask to take in the smell of the woody, damp forest that is not exactly grassy. I observed a myriad of adaptations the flora of FWSF that must cope with the hydric (anoxic) soils! We call these the hydrophytic plants.

Exposed, prop roots of (a) Java almond (Sterculia foetida) on the left and (b) Screwpine (Pandanus spp.) on the right enables gas exchange above the anoxic soils

Hanguana malayana are native herbaceous plants and their roots are great spots for dragonflies to hang out!

On left, Marsh Pulai (Alstonia spatulata) is a vulnerable, native species which gave the Keppel Discovery Wetland its original name, Pulai Marsh and (b) on right, its whorled leaves arrangement

Prof Gretchen fascinating over the flowers of the Barringtonia reticulata that is usually found further inland but the limited space of the Keppel Discovery Wetland limits the zonation belts

Crossing a bioswale that helps to drain water naturally during high rainfall events

After immersing in the biodiversity of the Keppel Discovery Wetlands, Samuel, a soil enthusiast shared on the methods used to understand soil characteristics through sampling soil moisture, soil texture and examining the soil profile! It is intriguing how soil tells so much about the site!

Samuel referred to the Munsel Colour Chart to determine the soil colour

(a) On left, the layers in the soil profile is not distinct and the top layer is possibly soil that was added on site (b) on right, it is evident that the soil at Keppel Discovery Wetlands is a random mix of clay, sand and silt, unlike the soil profile of a natural FWSF

Soil texture is determined by rubbing the soil into a ribbon

The probes of the Field Scout 300 TDR (Time Domain Reflectometry) Soil Moisture Meter measure the water content of the soil

Other monitoring techniques that I found interesting were (a) on left, the Bushnell camera traps were operated by batteries like this and (b) on right, the CNPS cover diagrams to refer to after looking through a densitometer to derive the aerial cover of tree canopy

Indeed, botanic gardens are highly undervalued conservation spaces for educating the public (like myself) and also constitute beacons of hope! Our guided walk and experience in trying out various monitoring techniques ended when the sunset but my learning has only just begun. I could not help but ponder on what Prof Gretchen said when we were looking at the invasiveness of the hydrillas. It has been a few months since regular clearing of hydrilla has halted as the standard five-year restoration funding has ended and hydrilla soon found its way across the entire wetlands! This reminded me of how costly it is to maintain restoration projects and the almost irreversible impact of man’s action.

Hydrilla explodes at two different sites of the Keppel Discovery Wetlands

I hope that my reignition in hope resonates with you. I believe conservation and restoration of the Keppel Discovery Wetlands can still persist in the millenniums to come. This can manifest through citizen science and also monthly volunteering opportunities to clear the hydrilla and other invasive aquatic species monthly. Hopefully then, the otters will be able to swim freely in the wetlands again and a primary freshwater swamp forest develops for our future generations to witness.

Written by: Ophelia ONG XING JIE