Ecology of Paphiopedilum rothschildianum at the type locality in Kinabalu Park (Sabah, Malaysia)

Abstract

Rothschild’s slipper orchid (Paphiopedilum rothschildianum), originating from Kinabalu Park in the Malaysian state of Sabah, on Borneo Island, is one of the most famous orchid species in the world. It caused a sensation when it was first discovered in the nineteenth century, and the precise details of its habitat were long kept a (trade) secret. The species is now widely available as a result of artificial propagation in culture, but the ecology of this species in the wild remained largely unknown. An expedition was organised by the authors to collect detailed habitat information, and to perform chemical analysis on P. rothschildianum leaves and associated rhizosphere soils. The species occurs on serpentinite (ultramafic) landslides at 500–1800 m asl on slightly acidic (means ranging from pH 5.8–6.7) soils with a cation exchange complex dominated by magnesium. The nutrient status (rhizosphere soil concentrations of phosphorus and potassium) is low, both the plant-available fraction and the total concentrations. The extreme soil chemistry was also reflected in the P. rothschildianum leaf chemistry with low concentrations of these elements and low foliar nitrogen, potassium and phosphorus. Reciprocal transplantation of P. rothschildianum on non-ultramafic soils has proven successful, which shows that soil chemistry is not limiting its growth, at least in culture. Rather, P. rothschildianum is restricted to open vegetation with a lack of competition brought about by a very unusual combination of factors: recurring landslides setting back vegetation succession, and extreme soil chemistry limiting plant establishment. Finally, the IUCN Red List status of P. rothschildianum and other Paphiopedilum-species of Kinabalu Park was provisionally assessed.