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Forest Vines to Snow Tussocks: The Story of New Zealand Plants


Cycles (Fig. 64)

Field observations by a number of botanists have led to some questioning of the above sequence of events. Some have suggested that, rather than there being a succession leading to a climax, there may in fact be repetitive cycles. For example, on the volcanic plateau of the central North Island it has been observed in forests with emergent podocarps page 108over a main canopy of kamahi, or kamahi and tawa, that where a podocarp falls the gap is occupied by tree ferns. Kamahi establishes epiphytically on the tree ferns and podocarps then regenerate under the kamahi and eventually overtop them.66,67 A similar sequence has been observed in south Westland.68

Probably because of their importance as timber trees, the lack of regeneration of podocarps in some New Zealand conifer broadleaf forests has received particular attention. According to the successional and cyclic hypotheses just reviewed this would be a normal consequence of forest development.