What constrains the distribution of orchid populations?

Abstract

Summary The distribution and abundance of orchid populations depend on a suite of biological and ecological factors, including seed production and dispersal, availability of mycorrhizal fungi and appropriate environmental conditions, with the weighting of these factors depending on the spatial scale considered. Disentangling the factors determining successful orchid establishment represents a major challenge, involving seed germination experiments, molecular techniques and assessment of environmental conditions. Identification of fungi from large‐scale surveys of mycorrhizal associations in a range of orchid species has shown that mycorrhizal fungi may be widespread and occur in varied habitats. Further, a meta‐analysis of seed introduction experiments revealed similar seed germination in occupied and unoccupied habitat patches. Orchid rarity was also unrelated to mycorrhizal specificity. Nonetheless, seed germination within sites appears to depend on both biotic and abiotic conditions. In the few cases that have been examined, coexisting orchids have distinct mycorrhizal communities and show strong spatial segregation, suggesting that mycorrhizal fungi are important drivers of niche partitioning and contribute to orchid coexistence. A broader investigation of orchid mycorrhizal fungus distribution in the soil, coupled with fungus and recruitment mapping, is needed to translate fungal abundance to orchid population dynamics and may lead to better orchid conservation.

Cypripedium calceolus (Orchidaceae) in Central Russia: a case study for its populations in two protected areas in the Republic of Mordovia (Russia)

“…A high proportion of species have declined in abundance and are considered to be rare, threatened, or endangered, primarily as a result of habitat loss (Kull & Hutchings 2006, Pillon & Chase 2007. Patterns of orchid richness are regulated by habitat size and elevation range at large scales (Acharya et al 2011), while by light availability, soil moisture, canopy height and area (especially for the epiphytic orchids) at fine scales (McCormick & Jacquemyn 2014). LANKESTERIANA About 130 orchid species belonging to 42 genera are documented in the Russian Federation (Varlygina 2011).…”

“…It includes about 880 genera with more than 25,000 species in the world (Cribb et al 2003). Due to mycorrhizal specificity (McCormick & Jacquemyn 2014), pollinator specialization (Cozzolino & Widmer 2005) and limited germination rates (Dearnaley et al 2012), most orchids are extremely susceptible to habitat disturbance as compared to other plants (Cozzolino & Widmer 2005, Jacquemyn et al 2007. Orchids frequently occur in very specific habitats (Wotavova et al 2004).…”

Comparative Chemical Characterisation of Soils at Cypripedium Calceolus Sites in Latvia

“…The great majority of mycorrhizal fungi associated with the Cypripedium genus are members of narrow clades within the fungal family Tulasnellaceae (Shefferson et al, 2005). It is possible that rare occurrence of the fungus or its specific environmental demands may affect occurrence of orchid species (McCormick and Jacquemyn, 2014). Phosphorous concentration in orchid leaves was sufficient in all of the sites studied, with values from 0.20 to 0.24, except at Egïupe, where the soil P concentration was also low.…”

Terrestrial orchids in a tropical forest: best sites for abundance differ from those for reproduction

“…A central goal in ecology is to understand the underlying mechanisms that determine where a species is found (Brown et al 1995, Brotons et al 2004, Cunningham and Lindenmayer 2005, McCormick and Jacquemyn 2014 and how this relates to fitness (Mro´z andKosiba 2011, Lasky et al 2014). Species distribution modeling (SDM) can provide valuable insights on the environmental characteristics underlying where a species is located (Franklin 2009, Peterson et al 2011).…”

“…Using a combination of both presence-absence and abundance data within SDMs can help to distinguish between sites suitable not only for colonization, but also for recruitment or survival (Brown et al 1995). Identifying factors that influence population distributions or establishment is an important, yet challenging, goal for organisms with complex ecological relationships that change depending on life history stage (Tremblay et al 2006, Comita et al 2009, McCormick and Jacquemyn 2014.…”