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Figure 7.1. Bromeliaceae on rocky substrates. (A) Tillandsia recurvata growing as an epiphyte on a lithophytic shrub while nearby Tillandsia kurt-horstii is anchored just as exclusively on the surrounding rock in south Bahia State, Brazil. (B) Unidenti ed Encholirium sp. featured in E dislodged to expose its extensive super cial root system. (C) Tillandsia tenuifolia forming a characteristic debris-collecting colony on

Figure 7.1. Bromeliaceae on rocky substrates. (A) Tillandsia recurvata growing as an epiphyte on a lithophytic shrub while nearby Tillandsia kurt-horstii is anchored just as exclusively on the surrounding rock in south Bahia State, Brazil. (B) Unidenti ed Encholirium sp. featured in E dislodged to expose its extensive super cial root system. (C) Tillandsia tenuifolia forming a characteristic debris-collecting colony on conditions in situ. Next, the bromeliads are treated as components of communities, with an examination of how they affect co-occurring vegetation and interact with neighboring fauna. Our review concludes with effects on integrative processes in ecosystems, primarily mineral cycling and energetics. Once again the epiphytes receive top billing, but only because less is known about the terrestrials. For the moment, cultivated Ananas comosus and related Bromelia humilis, plus a scattering of additional, soil-rooted species, must represent this more broadly varied of the two ecologically distinct groups of bromeliads.

Frost-tolerance

Bromeliaceae range higher into montane habitats to above 4000 m, and farther poleward than members of several other sizable, predominantly tropical families (e.g., Arecaceae). However, relatively few populations, just a handful including members of Tillandsia, Greigia, Chilean Ochagavia and closely related Fascicularia, Puya (Fig. 14.2C) and a scattering of other Pitcairnioideae, regularly experience subfreezing temperatures. Tolerance for more protracted frost at higher latitudes is even less common. More precisely, geographic ranges, plant morphology and mostly undescribed ecophysiology divide frost-tolerant Bromeliaceae into two categories.

Several species of Puya, and similarly long-lived "giant rosette herbs in several other families (e.g., Asteraceae, Lobeliaceae), comprise a convergent ora native to tropical alpine habitats around the globe (e.g., also Africa, Hawaii). Frost and intense UV-B-enriched radiation oblige congested, highly re ective foliage often invested with a dense indumentum of woolly trichomes (Fig. 7.2). Sunrise ends the nightly cooling cycle, which if much extended would overwhelm the well-insulated but otherwise vulnerable shoot meristem. Small size increases risk to the extent that only the rare seedling survives beyond the rst year or two of life. Miller and Silander (1991) reported that virtually every specimen of large-bodied Ecuadorian Puya clava-herculis to reach a certain modest size eventually owers, an achievement that requires a nurse plant, usually a tussock grass rather than a shrub or high cushion or mat-forming type.

the side of a granite outcrop in Bahia State, Brazil. (D) Alcantarea sp. on a granite outcrop in Rio de Janeiro State, Brazil. (E) A near monoculture of a lithophytic Encholirium sp. in Bahia State, Brazil. (F) Orthophytum sp. on granite in northern Minas Gerais State, Brazil. (G) Seedlings of lithophytic Tillandsia araujei and an unidenti ed Vriesea sp. illustrating the rough texture of this highly stable medium.

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