Brief Abstract:

Worldwide, agricultural intensification has caused biodiversity loss. The New Zealand dairy industry relies on its ?clean & green? image for market access. However, given the recent increase in consumer demands for environmentally-sustainable food production systems, the dairy industry may need to work on promoting native biodiversity on dairy farms, to secure market access in the future.  Dr Fukuda investigated the ways in which biodiversity conservation could be promoted on dairy farms, using three approaches: 1) a survey on farmers? attitudes towards tree planting and shelterbelt management on their properties; 2) a field study on the effects of farming practice and shelterbelts on invertebrate biodiversity and 3) a manipulative field experiment to investigate the effects of native tree corridors on invertebrate dispersal on farms.

There were 457 returns of the survey from the 2000 farmers approached.  Respondents identified their current levels of tree planting, their main reasons for planting them, and the barriers to planting more trees.  The rank order of importance of barriers to more planting turned out to be: insufficient space/competition with grass production, fencing costs, maintenance costs, the farmer did not see benefits from planting, labour costs, and cost of purchasing trees).

Field study of a random selection of 2-6 shelterbelts within each of 6 pairs of conventional and organic farms detailed (a) shelterbelt attributes (the origin of shelterbelt trees, conifers vs. broadleaves, fenced or unfenced, stature, porosity) and (b) spider and beetle abundance and diversity above and underneath shelterbelt litter and in adjacent pastures.  In general invertebrate biodiversity increased when native trees were provided for shelter, when the shelterbelts were fenced and where farm management was organic.

Field experiments deployed mahoe shrubs placed at 20, 60 and 180 m intervals from native forests on four Waikato Dairy farms and monitored the colonisation and population establishment of native insects.  Spread of some insects was most rapid and extensive when the shortest planting interval (20m) was used, but most forest insects did not colonise the plants in pasture at all. In general farmers should design new plantings to maximise ecological connectivity and colonisation and restoration of native invertebrate biodiversity may take decades.