Pilot trials of secondary seed dispersal potential from tree weta frass by the endemic dung beetle, Saphobius edwardsi in the Punakaiki Coastal Restoration Project, New Zealand

Abstract

There has been little research to our knowledge on quantifying ecosystem functions such as potential secondary seed dispersal of endemic dung beetles in New Zealand, especially on the West Coast. The Punakaiki Coastal Restoration Project (PCRP) site is adjacent to the 20.2 ha Nikau Scenic Reserve which is a rare remnant of lowland coastal forest opposite Paparoa National Park within the Punakaiki Ecological District. The site was cleared and surveyed for mining, then farmed until around 1970. It is now the centre of a restoration project to restore a functioning ecosystem while promoting conservation and tourism. As part of the PCRP we investigated the potential of S. edwardsi in providing secondary seed dispersal as an ecosystem function. Our objectives were to gain some understanding on whether S. edwardsi utilised tree weta frass, quantifying frass utilised per night, the distance S. edwardsi travelled per night, seed burial depth and what seeds could be dispersed by tree weta at the site which have potential for secondary seed dispersal by S. edwardsi. We hypothesised that S. edwardsi would utilise 0.01 g of tree weta frass/night/beetle and move a maximum distance of 5 m/night while burying dung and seeds a maximum depth of 40 mm which would allow most seeds to germinate. This information would enable the estimation of the population density, recycling of organic and potential secondary seed dispersal of S. edwardsi at the restoration site.