Host affinity and vertical distribution of epiphytic orchids in a montane cloud forest in southern Mexico

Abstract

<p class="Standard1"><strong>Background</strong>: The host´s structural characteristics provide diverse microhabitats that influence the distribution patterns of the epiphytes at different vertical zones and among tree species.</p><p class="Standard1"><strong>Hypotheses</strong>: Epiphytic orchids have preference for larger host trees and with non-exfoliating rough bark, while the limiting hosts will be those of smaller size and smooth and exfoliating bark, and there will be fewer individuals in the upper canopy of the host trees because the micro-environmental conditions are more stressful compared to the middle and lower parts of the host trees.</p><p class="Standard1"><strong>Methods</strong>: The host preferences and vertical distribution<strong> </strong>of the epiphytic orchids were analyzed in 20 montane cloud forest fragments. In each fragment, two transects of 2 × 50 m were drawn, and the trees with a diameter at a breast height ≥ 20 cm were recorded. In each tree, basal area was quantified and bark texture was characterized. In each tree and vertical zone, the orchid species present were identified and quantified.</p><p><strong>Results</strong>: Orchid distribution patterns vary between vertical zones and host tree species, and the richness is related to host size and bark texture. The highest species richness and number of epiphytic orchid’s individuals were recorded in host trees with fissured bark and larger size. The distribution of orchids in the host was not homogeneous nor was it related to any particular host species. However, five trees species were considered as host preferred, while five tree species were limiting hosts. The highest richness was recorded in vertical zone II and the lowest in zones I and V.</p><p class="Standard1"><strong>Conclusions</strong>: Larger trees contain greater richness of epiphytic orchids, because they offer better conditions for their establishment, provide a great diversity of microhabitats, greater time and area for epiphytic colonization events. The texture of the bark is a relevant factor in the host preference, and in the hosts with smooth bark, the presence of epiphytic orchids depends on the accumulation of organic matter.</p>

Laelia anceps Lindl. (Orchidaceae) adaptation on phorophytes within an anthropized landscape, Amatlán de los Reyes, Veracruz, Mexico

“…with fissured and slightly fissured bark, respectively, favored early emergence of new roots and longer root length. These observations are in agreement with the research by Hernández-Pérez et al (2018) in which a higher wealth and abundance of orchids was found in 23 species of fissured-bark trees and a lower wealth in 12 species of smoothbark trees. Similarly, Alzate-Q et al (2019) found that the phorophyte Clethra macrophylla presented a higher richness of epiphytic species (41%) related to its multiple branches and rough bark.…”

Relações ecológicas entre orquídeas e forófitos em Floresta Ombrófila Mista sob influência nebular, Planalto Serrano Catarinense

“…Zotz & Vollrath (2003) afirmam que a ocupação epifítica, assim como, a abundância por forófito, correlacionam-se axiomaticamente, com a idade da árvore e área do substrato. Existindo assim, uma especificidade entre orquídeas e altura e diâmetro do forófito (Hernández-Pérez et al 2018). À medida que as árvores crescem, tanto em diâmetro, quanto em altura, contribuem para mudanças na estrutura da sinúsia epifítica, aumentando a heterogeneidade de micro-hábitats, especialmente, dentro das copas (Woods et al 2015).…”

“…Esta espécie também foi verificada colonizando caule (colmo) de taquaras, em locais adjacentes a área de estudo. Estas variações de abundância, na estratificação vertical, ou preferências por zonas do forófito são, comumente, evidenciadas em outros estudos sobre epífitos (Zimmerman & Olmestd 1992;Rogalski & Zanin 2003;Kersten & Silva 2001;Hernández-Pérez et al 2018).…”

“…Estudos em assembleias de epífitas descrevem que troncos rugosos têm maiores probabilidades de ocupação (Callaway et al 2002;Medeiros et al 2014). Entretanto, outros autores elencaram ritidomas fissurados como as mais importantes na colonização de orquídeas, enfatizando que a espessura é fundamental (quanto mais espessa, maior a colonização) (Hernández- Pérez et al 2018). Características presentes no ritidoma rugoso facilitam o acúmulo de material orgânico e água, recursos fundamentais para ampliar o sucesso de colonização e o estabelecimento das epífitas (Callaway et al 2002;Medeiros et al 2014;Wagner et al 2015).…”

“…As Orchidaceae, assim como outras epífitas, podem demonstrar preferência por algum forófito. Esta relação pode decorrer devido a propriedades ou características do forófito, como o tipo da casca, características arquiteturais (Wagner et al 2015) e do tamanho da árvore (Hernández-Pérez et al 2018).…”