BIOTROPICA 37(3): 457–461 2005 10.1111/j.1744-7429.2005.00060.x Epiphyte Orchid Establishment on Termite Carton Trails 1 Alejandro Flores-Palacios 2 and Ra´ ul Ortiz-Pulido 3 Departamento de Ecolog´ ıa Vegetal, Instituto de Ecolog´ ıa A. C. Apdo. Postal 63, 91000, Xalapa, Ver., M´ exico ABSTRACT In the coastal zone of central Veracruz, Mexico, we recorded the abundance of orchid plants growing on termite carton trails or directly on the peeling bark of Bursera fagaroides. Although only 19 percent of the surveyed trees contained termite carton trails, trees with termites hosted 92 percent of all orchid individuals. A disproportionate number of orchid seedlings occurred on termite cartons given the relative availability of carton and bark substrate. Our results show for the first time that orchids can establish on termite trails, and we discuss the potential for termite facilitation of orchid populations. RESUMEN En la zona costera de la regi´ on central de Veracruz, M´ exico, documentamos la abundancia de orqu´ ıdeas sobre senderos de cart´ on de termitas y sobre la corteza exfoliante del ´ arbol Bursera fagaroides Engl. (Burseraceae). Aunque solamente el 19 por ciento de los ´ arboles investigados ten´ ıan senderos de termitas, estos albergaban el 92 por ciento de las orqu´ ıdeas. Un n´ umero desproporcionado de pl´ antulas de orqu´ ıdea crec´ ıan sobre el cart´ on de las termitas a pesar de la abundancia relativa de cart´ on y corteza. Nuestros resultados demuestran, por primera vez, que las orqu´ ıdeas pueden establecerse sobre senderos de termitas y discutimos la posible facilitaci´ on de las termitas en la poblaci´ on de orqu´ ıdeas. Key words: Bursera; Brassavola; epiphytes; Mexico; Myrmecophila; Nasutitermes; safe sites; tropical dry forest. EPIPHYTES FACE A SPATIAL AND TEMPORAL MOSAIC OF SUBSTRATES on which they can establish, but substrate quality varies. Epiphyte population growth therefore depends on the abundance of safe sites (Bennett 1986, Ackerman et al. 1996). One strategy for dealing with this environmental variability is the development of seeds that have a high germination capacity on any substrate (Benzing 1990), causing the host species to be unimportant (Callaway et al. 2002). There are, however, host species (e.g., trees with peeling bark) that have consistently fewer epiphytes, suggesting that their characteristics prevent epiphyte establishment (Johansson 1974). Many epiphyte species establish directly on tree bark, and it has been shown that their success depends on several factors such as the presence or absence of alellochemicals, the water-holding capacity of bark, and bark stability (Frei 1974, Castro-Hern´ andez et al. 1997, Callaway et al. 2002). Other epiphytes establish on trees due to the presence of facilitators such as fungi, lichens, or ant carton structures. Some epiphytes are dispersed by ants or in the fecal material of vertebrates and deposited within a pool of organic matter (Longino 1986, Davidson 1988, Catling 1997). Some tropical epiphytes are facilitated by ant activity, and the interaction between ants and epiphytes has received much attention. This interaction is sometimes a mutualism: ants can disperse epi- phyte seeds to safe sites where the epiphytes receive protection and 1 Received 25 June 2004; Revision accepted 3 December 2004. 2 Corresponding author. Current address: Departamento de Ecolog´ ıa y Conser- vaci´ on, CEAMISH, Universidad Aut´ onoma del Estado de Morelos, Av. Uni- versidad 1001, Col. Chamilpa, 62000, Cuernavaca, Morelos, M´ exico; e-mail: alejandro.florez@uaem.mx 3 Current address: Laboratorio de Ecolog´ ıa de Poblaciones. Centro de Investi- gaciones Biol´ ogicas, Universidad Aut´ onoma del Estado de Hidalgo, A. P. 69, Pachuca, Hidalgo, 42001, M´ exico; e-mail: raulortizpulido@yahoo.com nutrition, while the ants obtain food and use epiphytes as nests or to form part of their carton nest structure (Longino 1986, Rico-Gray et al. 1989, Yu 1994, Catling 1997). In Neotropical canopies, ter- mites of the genus Nasutitermes (Isoptera: Termitidae) are also com- mon. Like ants, they use epiphyte resources, and they may compete with ants for access to epiphyte domatia (sensu Huxley 1980) and for tree holes in which to make nests (Thorne et al. 1996a, 1996b; Dejean et al. 2003). However, epiphytes rarely use carton struc- tures made by termites. Bl¨ uthgen et al. (2001) suggested that a termite carton has a lower nutrient content and is harder than an ant carton. We report here the first account of epiphytic orchid es- tablishment on carton-covered foraging trails made by a nasutiform termite. This study was conducted at “La Mancha” Coastal Research Center (CICOLMA, 19 ◦ 35 ′ 12 ′′ N–19 ◦ 36 ′ 18 ′′ N, 96 ◦ 22 ′ 18 ′′ W– 96 ◦ 23 ′ 24 ′′ W, 0–150 m asl) in Veracruz, Mexico. The climate is warm and subhumid, with an average minimum temperature of 18 ◦ C and an average maximum of 34 ◦ C; total annual rainfall ranges from 1200 to 1500 mm and is concentrated in the summer (Castillo- Campos & Medina-Abreo 2003). There are eight different vegeta- tion types at CICOLMA. This research was done in savannah-type vegetation (Castillo-Campos & Medina-Abreo 2003), an herba- ceous community with abundant isolated dwarf trees. The trees are 3–7 m in height, and characteristic species are Bursera fagaroides Engl. var. purpusii (Brandegee) McVaugh & Rzed. (Burseraceae) (hereafter B. fagaroides), Byrsonima crassifolia (L.) HBK (Malpighi- aceae), and Coccoloba barbadensis Jacq. (Polygonaceae). The most frequent epiphytes in savannah trees are bromeliads, but there are also orchid species, the most abundant being Brassavola no- dosa (L.) Lindl. and Myrmecophila grandiflora (Lindl.) Carnevali, 457