Vascular epiphytes in the temperate zones–a review

Abstract

Vascular epiphytes are typically associated with tropical rainforests, whereas their occurrence in temperate forests is little appreciated. This review summarises the available information on epiphytism in the temperate zones ͑ Ͼ 23.5°latitude͒, which has not been reviewed comprehensively for more than a century, and critically analyses the proposed mechanisms behind the observed biogeographical patterns. Although in the temperate zone epiphytic vascular plants are rarely as impressive as in tropical forests, there are noteworthy exceptions. Temperate rain forests of Chile and New Zealand, or montane forests in the Himalayas are comparable to many tropical forests in terms of epiphyte biomass and diversity, but differ in their taxonomic spectrum: temperate epiphyte communities are generally dominated by ferns and fern-allies. Other temperate areas are not, however, necessarily barren of epiphytes, as repeatedly implied. Quite in contrast, local populations of epiphytes in a large number of other non-tropical areas in both the southern and the northern hemisphere can be quite conspicuous. The proposed reasons for the latitudinal gradients in epiphyte abundance and diversity ͑water scarcity or low temperatures͒ are not fully convincing and, moreover, still await experimental verification. Other factors, both historical ͑e.g., Pleistocene extinctions͒ and ecological ͑e.g., prevalence of conifers in the northern hemisphere͒, should also be taken into consideration to obtain a comprehensive explanation of the extant global distribution of vascular epiphytes.

Drought and extreme temperature tolerance for <em>Tillandsia dasyliriifolia</em>, an epiphytic bromeliad from the northern coastal dune scrubland in Yucatan, Mexico

“…As a general rule, low temperatures are used to explain species abundance in colder regions mainly because of damage by frost (Zotz, 2005). Low temperature causes change in carbohydrate metabolism, hormonal regulation and inhibit or decreases plant growth (Nievola et al, 2005;Guy et al, 2008;Hua, 2009;Mollo et al, 2011).…”

“…However, for the atmospheric Tillandsia usneoides (L.) L. low temperature is not limiting (Garth, 1964). Similarly, for Polypodium vulgare L., an epiphytic fern, long severe expositions to frost don't lead to visible damage (Zotz, 2005). Studies of tolerance to high temperatures in epiphytes are lacking.…”

“…Three of the most important ecological factors influencing plant development and distribution are water, irradiance and temperature (Adams et al, 1997;Lambers et al, 2008;Smith et al, 1997;Zotz 2005).…”

Vascular epiphytes at the treeline – composition of species assemblages and population biology

“…This probably reflects the fact that tree crowns buffer against radiation frost (Aussenac, 2000), and we measured air temperatures in the central crowns of four Comarostaphylis arbutoides trees. Although some frost tolerance has been documented for vascular epiphytes (Halbinger, 1941;Jenkins, 1999), potential protection of epiphytes against frost by host tree crowns may be relevant when discussing altitudinal and latitudinal limits to epiphyte occurrence, where frost is frequently invoked as a prime limiting factor (Kessler, 2002;Zotz, 2005).…”

Diversidad y abundancia de bromelias epifitas en “El Punto” Santa Catarina Ixtepeji, Oaxaca

“…Los bosques cuentan con variaciones en temperatura y humedad, los cuales en niveles bajos son los principales factores ambientales limitantes en la diversidad y abundancia de epifitas como lo son las bromelias (Acebey y Kromer, 2001;Zotz, 2005;Rzedowsk, 2006;San Martín et al, 2008). Otro aspecto de suma importancia relacionado con la diversidad es la identidad del forófito.…”