The diversity and conservation status of pakihi vegetation in north Westland

Twenty-eight areas of pakihi vegetation in 7 Ecological Districts in north Westland were sampled using non-area plots and analysed by TWINSPAN and DECORANA. Soil profile data and manuka stem ages were recorded. Twelve plot groupings were identified ranging from forest to scrub and open herbaceous vegetation. The main factors determining the regional patterns are drainage, nutrient status, and fire frequency. Most pakihi areas supported forest, many of them in European times. They are being invaded by manuka, which in turn is being invaded by potentially taller tree species.

Pakihi bird species are either characteristic of higher altitudes, widespread, or more common at lower altitudes, or widespread. The lower altitude species include many of the more distinctive pakihi birds more common in open pakihi. In contrast, fernbirds which have been a major stimulus for conserving pakihi, prefer structurally complex vegetation. This raises questions for management of pakihi reserves. There are many good reserves, but there is potential for improving the regional coverage.