Orchid diversity in antropogenic-induced degraded tropical rainforest, an extrapolation towards conservation

Abstract

The uncontrolled logging in Peninsular Malaysia and the resulting mudslides in the lowland areas have been perilous, not to just humans, but also to another biodiversity, including the wild orchids. Their survival in these highly depleted areas is being overlooked due to the inaccessible and harsh environment. This paper reports on the rescue of orchids at risk from the disturbed forests for ex-situ conservation, the identification of the diversity of orchids and the evaluation of the influence of micro-climatic changes induced by clear-cut logging towards the resilience of orchids in the flood-disturbed secondary forests and logged forests in Terengganu and Kelantan, located at the central region of Peninsular Malaysia, where the forest destruction by logging activities has been extensive. 109 orchid species belonging to 40 genera were collected from the disturbed areas. The diversity and data analyses show that the disturbed secondary forests had a higher orchid density (0.0133 plants/m2) than the logged sites (0.0040 plants/m2) as the habitat conditions were more dependable. Nevertheless, the logged forests harboured a higher diversity of orchids (H=4.50 and D=0.99) of which 97.9% were epiphytes. Eleven rare species were found along with six species endemic to Peninsular Malaysia, with two species new to science. The results highlighted the factors that allow the orchids to flourish or suffer in the disturbed forests. The logged forests had a higher ambient temperature and lower moisture level than the mud flood-disturbed and canopy-covered secondary forests. Apart from the extensive ground vegetation due to logs dragging extraction, low soil moisture and absence of leaf litter were believed to be the major attributes causing the low abundance of terrestrial orchids. The high abundance and diversity of epiphytic orchids and the large difference of their densities between the logged sites were influenced by the densities of fallen trees hosting orchid(s), disturbance-induced dryness stresses, durations of exposure to the anthropogenic-induced disturbance, and less favourable soil conditions for the terrestrial orchids.
 
 Key words: conservation, diversity, dryness stress, ecology, epiphyte, logged forest, mudslides, Orchidaceae

A checklist of vascular plants and uses of some species for livelihood-making in Setiu Wetlands, Terengganu, Malaysia

“…Thus, to date, there are 56 species of orchids found in SW from which 14 species were recorded by Siti Fatimah et al (2015) and 42 represent new records in SW, mostly being recent collections by Dome Nikong. The highest number of orchid species in SW, as expected, are in the widespread genera Bulbophyllum and Dendrobium , similar to the results of Besi et al (2019) in Tasik Kenyir logging sites. Both genera are found to be most abundant epiphytic orchids growing in disturbed and logged forests in which the weather and microclimate are favourable for growth and reproductive processes.…”

“…The Orchidaceae (Fig. 4 ) are well represented in SW, representing 23% of 245 orchid species recently reported in Terengganu ( Besi et al 2019 ). Thus, to date, there are 56 species of orchids found in SW from which 14 species were recorded by Siti Fatimah et al (2015) and 42 represent new records in SW, mostly being recent collections by Dome Nikong.…”

“…Both genera are found to be most abundant epiphytic orchids growing in disturbed and logged forests in which the weather and microclimate are favourable for growth and reproductive processes. However, orchid density is due in part to the severity of the disturbance in which highly disturbed logging sites harbour lower density than somewhat disturbed sites ( Besi et al 2019 ). Among the species recorded in SW, there are some that are exceptional.…”

Wild orchid diversity of highland forest in the Heart of Borneo: Long Banga and Tama Abu, Sarawak

“…It may probably be caused by the presence of large and varied types of host plants for epiphyte colonisation. It could be e�pected that shade�demanding species of Bulbophyllum, Dendrobium and Coelogyne would be in the highest abun� dance in canopy�protected forests with less direct e�posure to the sun rays as favourable (Ling & Sang, 2018;Besi et al, 2019b). These groups are mostly composed of highland orchid species with coria� ceous or leathery leaves, with or without pseudob� ulbs, and adapted only to wet and cool conditions (Seidenfaden & Wood, 1992;Wood et al, 1993;Besi et al, 2019b).…”

Macro- and micro-morphologies and conservation status of Hymenorchis javanica (Orchidaceae: Aeridinae): the only representative of the genus in Malaysia

“…Presumably, it might be probably due to the plants' sensitiveness and slow adaptation to sudden changes in irradiance, nutrients, and atmospheric-nitrogen deposition (Zhang et al 2018). Also, the plants are lacking pseudobulbous organs that can store nutrients and water during dry periods (Yang et al 2016;Besi et al 2019b). Though epiphytic orchids have greater capacity to conserve water and avoid the damaging effects of drought based on their root functioning (Li et al 2018).…”