Masting is a worldwide phenomenon but appears to be especially prevalent in the New Zealand flora (Webb and Kelly 1993, Schauber et al. 2002, Kelly and Sork 2002). One remarkable thing about masting here is that it is not only found in trees (the usual candidates overseas) but also in herbaceous plants, such as grasses, Aciphylla species (Apiaceae), and New Zealand flax (previously in Agavaceae, recently moved into Phormiaceae). The ultimate reasons for high masting prevalence in New Zealand are mysterious, but New Zealand’s long history before humans and mammalian herbivores arrived may have enabled even herbs and grasses to evolve long life spans, which are necessary for masting to be a viable strategy.
Webb and Kelly (1993) provide a table listing some of the diverse families which have masting species in New Zealand. The masting genera are ecologically diverse in several respects:
- Chionochloa (snow tussocks) have wind-pollinated flowers and gravity-dispersed seeds. Several Chionochloa suffer severe predispersal predation on seeds and florets by specialist insects, and masting appears to benefit the plants by satiating these predators (Kelly et al. 1992, Kelly and Sullivan 1997, Kelly et al. 2000).
- Nothofagus (southern beeches) are angiosperm trees of lowland and montane habitats noted for producing highly variable seed crops over large spatial scales (Wardle 1984, Allen and Platt 1990, Burrows and Allen 1991). Nothofagus have wind-pollinated flowers and wind-dispersed seeds; the latter are important foods for a variety of native birds (Wardle 1984, Wilson et al. 1998), as well as introduced birds and rodents (King 1983, O'Donnell and Phillipson 1996).
- Phormium spp. (New Zealand flax, or harakeke) have large bird-pollinated flowers and dry wind-dispersed seeds. The larger species, P. tenax, grows mostly in damper lowland habitats, while the smaller species P. cookianum has an upland distribution.
- Dacrydium cupressinum (rimu) is a long-lived conifer in the Podocarpaceae which inhabits lowland and lower montane habitats. Rimu cones are wind-pollinated, while the seeds are carried on fleshy podocarps, which are dispersed by several native birds (Norton and Kelly 1988, O'Donnell and Dilks 1994).
|flax in Otago|
|Craigieburn beech forest||rimu|
|beech tree flowers||snow tussock|