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Orchids: Flagship species for monitoring sensitive global ecosystems
By: S. K. Basu1 and W. Cetzal-Ix2*
Orchidaceae is the largest family of flowering plants with ~ 24000 distributed globally and is divided into six separate sub-families: Apostasiodeae, Cypripediodeae, Epidendroideae, Orchidoideae and Vanilloideae. This fascinating family of flowering plants is distributed widely in the tropical sub-tropical belts and some restricted temperate regions of the continents of Asia, Africa, Oceania; and in the North and the Neotropics of the Latin Americas. Orchids survive in a wide diversity of habitats and ecological zones and a spectacularly successful group of flowering plants that have migrated and evolved to slowly become one of the most astounding and diversely distributed families of flowering plants. The species of this family are particularly dominant and abundant in the ecosystems of tropical rainforests and temperate regions with high humidity. The plants are pollinated by mechanical means as well as by several biological pollinators such as small mammals, birds and a wide diversity of insect species. Majority of orchids being epiphytes are abundant on high canopy forming trees of the forest and hence represent a special niche of the existing forest ecosystem. Orchid flowers are known all over the world for their spectacular form, shape, color and fragrance; and hence have attracted botanists, horticulturists, nursery and greenhouse businessmen dealing with expensive, spectacular and exotic ornamental plants and general public at large. Expensive orchids add grace to a floral bouquet all over the planet. Due to such extreme ornamental values orchids across the world have been exposed to serious over-exploitation, illegal harvest, trade and trafficking exposing several orchids from the tropics and neotropics almost to the verge of extinction. Several anthropogenic factors such as encroachments within forested areas and sensitive ecosystems, cattle grazing, uncontrolled forest fires, timber trade, devegetation, habitat fragmentation, shifting cultivation practices, climate change etc have been impacting orchid populations globally. Since orchids are associated with the canopy forming tree species in any major forest ecosystems in the tropics, subtropics, Neotropics and certain temperate regions like eastern Himalayas, they represent an unique ecosystem and habitat of their own within a distinct ecosystem. In other words, orchids represent “micro-ecosystem” with their own species, their distinct pollinators and host and semi-host tree species and micro-climatic regimes within broad major, “mega-ecosystems”. Hence, they are being currently, potentially exploited by researchers as an important flagship species for monitoring sensitive and general health of a forest ecosystem. If an ecosystem represents a wide diversity (abundant biodiversity) of different orchid species in primary good health and in profuse numbers and are surviving, propagating, pollinating, disseminating, breeding and also producing different natural hybrids, that ecosystem broadly represents a healthy one with less anthropogenic impacts and holds promise for a better future. The orchid diversity can therefore be manipulated as target “flagship” species representing general health and conditions of an ecosystem and hence could easily be regarded as an environmental and ecological biomonitors or as plant biomonitors or phytomonitors.
1University of Lethbridge, AB, Canada; 2Centro de Investigación Científica de Yucatán, Mérida, Yucatán, México; *corresponding author: [email protected]
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