A habitat cascade is a common type of a facilitation cascade. where "indirect positive effects on focal organisms are mediated by successive formation or modification of biogenic habitat".
A habitat cascade is composed of at least three organisms: a primary habitat former or modifier; a secondary habitat former or modifier; and a focal organism that utilizes the secondary habitat former or modifier. For example, primary habitat forming trees can provide habitat for secondary habitat forming epiphytes, lianas, or vines that again can provide habitat to focal organisms like insects and birds.
The primary vs. secondary habitat formers are sometimes referred to as ultimate vs. proximate habitat formers, basal vs. intermediate habitat formers, primary vs. secondary ecosystem engineers, primary vs. secondary foundation species,Angelini, C., et al., Interactions among foundation species and their consequences for community organization, biodiversity, and conservation. BioScience, 2011. 61: p. 782-789. basibionts vs. epibionts, basizoids (if animal) or basiphytes (if plant) vs. epizooids (if animal) or epiphytes (if plant),Wahl, M., Epibiosis Ecology, Effects and Defences Ecological Studies, Marine Hard Bottom Communities, Part 1, 2009. 206: p. 61-72. or hosts vs. structural parasites. Focal organisms have been referred to as clients, end-users, habitat-users, inhabitants or hyperepibionts
Secondary habitat formers are typically attached to, entangled around, or embedded within the primary habitat former. Habitat cascades are strongest when the secondary habitat former is more effective than the primary habitat former at allowing focal organisms to avoid stress and enemies, and find resources and other facilitators.
Habitat cascades promote increased biodiversity in ecosystems dominated by large and long-lived sessile or slow-moving structural organisms. For example, habitat cascades have been documented in tropical forests, temperate forests,Díaz, I., et al., A field experiment links forest structure and biodiversity: epiphytes enhance canopy invertebrates in Chilean forests. Ecosphere, 2012. 3(1): p. 3:art5.Watson, D.M., Effects of mistletoe on diversity: a case-study from southern New South Wales. Emu, 2002. 102(3): p. 275-281. salt marshes,Dijkstra, J.A., J. Boudreau, and M. Dionne, Species‐specific mediation of temperature and community interactions by multiple foundation species. Oikos, 2012. 121(5): p. 646-654. coral reefs,Bergsma, G.S., Coral mutualists enhance fish abundance and diversity through a morphology-mediated facilitation cascade. Marine Ecology Progress Series, 2012. 451: p. 151-161.Bergsma, G.S., Mutualists alter coral susceptibility and response to biotic disturbance through cascading trait-mediated indirect interactions. Coral Reefs, 2012. seagrass beds,Edgar, G.J. and A.I. Robertson, The influence of seagrass structure on the distribution and abundance of mobile epifauna: pattern and processes in a Western Australian Amphibolis bed. Journal of Experimental Marine Biology and Ecology, 1992. 160: p. 13-31.Hall, M. and S. Bell, Response of small motile epifauna to complexity of epiphytic algae on seagrass blades. Journal of Marine Research, 1988. 46: p. 613-630.Thomsen, M.S., et al., Harmful algae are not harmful to everyone. Harmful Algae, 2012. 16(0): p. 74-80. mangrove stands,Bishop, M.J., J. Fraser, and P.E. Gribben, Morphological traits and density of foundation species modulate a facilitation cascade in Australian mangroves. Ecology, 2013. 94: p. 1927–1936. polychaete gardens, seaweed covered rocky coasts and mollusc reefs.Thomsen, M.S., et al., Effects of the invasive macroalgae Gracilaria vermiculophylla on two co-occurring foundation species and associated invertebrates. Aquatic Invasions, 2013. 8: p. 133-145.
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