ITS ANOTHER WARM, sunny summer day, ideal for tree growth. Just south of the Waiotapu pub, on the Rotorua-to-Taupo highway, I head into one of New Zealand’s largest pine forests, Kaingaroa Forest, to check my pitfall traps and see how many insects I’ve caught.

After parking the dusty ute and donning the usual high-vis reflective clothing, it’s into the blackberry and gorse that seem to protect the edge of many pine plantations from all but the most curious of people. In the open it’s already hot, but inside the forest it’s cool and damp, with a lush carpet of mosses and ferns underfoot. The first of my insect traps is only a few hundred metres inside; however, along the way there are several diversions. A fantail flitters behind me as I push through increasingly dense tree ferns and small native shrubs. Rotten tree stumps have been heavily damaged by a pig that has spent a recent evening feasting on the huhu grubs within. The remains of last night’s work by the local spiders sparkle with morning dew, and webs strung between trees catch my face.

My first pitfall trap is placed next to a grove of tree ferns. It consists of a plastic cup sunk to ground level with a rain cover and panels that guide ground-dwelling invertebrates to the central collecting pottles. A robin hops along to have a look at my haul of weta, millipedes, beetles, flies and a myriad other creatures. I transfer these to a jar of alcohol for later examination and move on, as I have only five days to check over 400 such traps spread throughout Kaingaroa and Tarawera Forests and some smaller neighbouring plantations. Besides which, Ecki, who is attending to the other half of the trap line in the adjacent compartment, will soon be waiting at the truck, and we still have another 11 trap lines to check before the end of the day.

How rich are our exotic pine plantations in native flora and fauna? It was Ecki who brought the biodiversity value of pine forests to my attention at the start of my studies. In his work in Rotoehu and Kaingaroa Forests (near Rotorua), Hochstetter Forest (on the West Coast) and Eyrewell Forest (in North Canterbury) he found a total of 202 native and 70 introduced plant species in only 60 small study plots. This number of native plants represents almost 10 per cent of New Zealand’s total, a very respectable figure indeed considering the small size of the area assessed. Plant diversity is pretty much confined to the understorey, however, the upper canopy in older stands consisting entirely of pine. So far my insect traps, part of a large-scale project investigating the impact of the size of clearfell harvest areas on invertebrate biodiversity in pine forests, are showing similar results. I’ve found over 350 species of native beetle alone, and the number keeps climbing.

Pine forests are a mosaic of stands of different ages, with recently harvested areas, young trees and mature pines in relatively close proximity. This provides a wide range of habitats, and also helps me to navigate. A forest-establishment map and an eye for different tree heights (and thus ages) allow me to find my way to various sites, despite the maze of unnamed roads that leave first-time visitors disoriented.

Introduced plant species such as buddleia, gorse, broom and grasses tend to dominate in the open—in harvested areas and skid sites (where timber is collected for transportation) and along
roadsides—although many natives are also present in these places. This tends to be all that the average passing motorist sees of the country’s pine plantations, which does little for an appreciation of the diversity of native plants in the understorey. to slip in under the cloud base.