LANKESTERIANA 7(1-2): 102-106. 2007.
SPATIAL STRUCTURE OF PLEUROTHALLIS, MASDEVALLIA,
LEPANTHES AND EPIDENDRUM EPIPHYTIC ORCHIDS IN A FRAGMENT
OF MONTANE CLOUD FOREST IN SOUTH ECUADOR
LORENA RIOFRÍO1,3, CARLOS NARANJO1, JOSÉ M. IRIONDO2 & ELENA TORRES2
Universidad Técnica Particular de Loja, San Cayetano Alto s/n, Loja, Ecuador
Universidad Politécnica de Madrid, Ciudad Universitaria s/n, E-28040 - Madrid, Spain
Author for correspondence: firstname.lastname@example.org
KEY WORDS: altitudinal range, colonization, phorophyte specificity, phorophyte trunk diameter, seed disper-
sal, spatial patterns
Orchids are the most diverse family of vascular dinal range of the fragment studied? Are there specif-
plants in Ecuador with 228 genera and nearly 4000 ic patterns in their spatial distribution resulting from
species. More than 60% of these species are epi- seed dispersal characteristics? Do plants of these
phytes, being Pleurothallis R.Br., Epidendrum L., orchids exhibit any preference over the trees where
Lepanthes Sw. and Masdevallia Ruiz & Pav., with they grow? Does phorophyte trunk diameter affect
472, 358, 314 and 226 species respectively, some of the establishment of these orchids? The results pre-
the genera with greater number of epiphytic orchids sented, although preliminary, provide useful informa-
(Dodson 1994-2003). tion for orchid management plans.
Although Ecuador is among those countries with the The study was carried out in a fragment of regener-
highest orchid biodiversity in the world, it also has one ated forest located on the Loja-Zamora Chinchipe road,
of the highest rates of deforestation: 1.2% of the coun- on the border of Podocarpus National Park (southern
try’s forests are lost each year (FAO 2005). Extensive Ecuador). The age of the forest is about 30 years old,
deforestation practices currently taking place pose a and it is characterized by a steep slope (51%), with
major threat for the survival of these orchids as they trees 5-8 m high and lianas that are over 10 m long.
are greatly dependent on the environmental conditions Mean annual precipitation is 2700 mm, and annual
of the forests that sustain them, and the host trees mean temperature is 15.5 º C (14.4 - 17.5 º C).
(phorophytes) on which they grow. Thus, understand- A total of nine 10 x 10 m plots were established at
ing of orchid-phorophyte interactions, as well as the 2200, 2230 and 2250 m a.s.l. (three plots in each alti-
patterns of spatial distribution and colonization in sec- tude). All trees (including fern trees), shrubs and lianas
ondary succession forests regenerated after deforesta- of diameter at breast height (DBH) over 1 cm were
tion, is essential for the in situ conservation. determined at the genus level, measured and mapped.
Nevertheless, few studies have been conducted in this The census included 1025 vascular plants belonging to
field, and scientific basis supporting population rein- more than 70 different genera. Miconia Ruiz & Pav.
forcement or reintroduction actions is scarce. (148 trees), Nectandra Rol. ex Rottb. (65 trees), Clusia
The purpose of this study is to assess the spatial L. (59 trees), Elaeagia Wedd. (59 trees) and Psammisia
distribution of epiphytic orchids of the above-men- Klotzsch (56) were the most frequent genera.
tioned genera in an Ecuadorian fragment of secondary Presence and abundance of all orchids occurring in
montane cloud forest to infer patterns of seed disper- the first 3 m height were also recorded. In this zone,
sal and colonization. In addition, the effects of phoro- which corresponds to zone 1 of Johansson’s scheme,
phyte identity and size on orchid establishment are the microclimatic conditions are relatively constant
analyzed. Specifically the questions posed are: Do the (Johansson 1974). In total 2798 orchids belonging to
distributions of Pleurothallis, Epidendrum, 12 genera were identified. Although it is difficult to
Lepanthes, and Masdevallia plants vary in the altitu- make comparisons between different researches