Quantifying anthropogenic threats to orchids using the IUCN Red List

Abstract

Orchids are diverse, occur in a wide range of habitats and dominate threatened species lists, but which orchids are threatened, where and by what? Using the International Union for Conservation of Nature Red List, we assessed the range and diversity of threats to orchids globally including identifying four threat syndromes: (1) terrestrial orchids in forests that are endemic to a country and threatened by illegal collecting; (2) orchids threatened by climate change, pollution, transportation and disturbance/development for tourism, and recreation activities, often in East Asia; (3) epiphytic orchids in Sub-Saharan Africa including Madagascar with diverse threats; and (4) South and Southeast Asia orchids threatened by land clearing for shifting agriculture. Despite limitations in the Red List data, the results highlight how conservation efforts can focus on clusters of co-occurring threats in regions while remaining aware of the trifecta of broad threats from plant collecting, land clearing and climate change.

Keywords: Conservation; Global biodiversity; Human impacts; Illegal plant collection; Threatened species.

Fig. 1

Bray–Curtis similarity resemblance plot showing the levels of similarity among threats to the 442 orchid species on the IUCN Red List

Fig. 2

The number of orchid species in different regions threatened by biological resource use, agriculture and aquaculture, human intrusion and disturbance or development, based on data for 442 species of orchids on the IUCN Red List

Fig. 3

The number of orchid species of each growth form affected by each of the major types of threats on the IUCN Red List, terrestrial species (light grey), epiphytic (mid grey) and lithophytic species (black)

Fig. 4

The number of Cypripedium (light grey) and Paphiopedilum (mid grey) orchids affected by the 11 major types of threats on the IUCN Red List compared to all other genera (black)

Fig. 5

Bray–Curtis similarity resemblance plot showing the levels of similarity among threats, land regions, habitats, endemism and growth form to the 442 orchid species on the IUCN Red List and the four identified threat syndromes labelled 1–4 based on percent similarity, including (1) terrestrial species of orchids in forests that are endemic to at least one country and that are threatened by illegal plant collection; (2) orchids in East Asia affected by climate change, pollution, transportation including roads and railroads, and disturbance/development for tourism and recreation activities; (3) epiphytic species in Sub-Saharan Africa including in Madagascar, but with a range of threats; and (4) orchids in South and Southeast Asia that are affected by land clearing for non-timber agricultural crops