TIME | 4 June 2009, 4pm onwards
LOCATION | Suite 12, Centre for Innovation, 87 St. David St.
SPEAKER | Dr. Yuki Fukuda
Beetles and spiders comprise more than one quarter of the world’s total species diversity. Globally, invertebrate diversity may be declining more rapidly than those of plants and vertebrates. Many reported decline in invertebrate diversity have been evident in agricultural landscapes where the original habitats have been cleared, pastures have been created and the inputs of chemicals have been increased through agricultural intensification. In New Zealand, agricultural intensification has been considered as one of the major causes of the decline of invertebrate biodiversity. Invertebrates, such as beetles and spiders, often immigrate from the surrounding landscape, and are also influenced by local management practices. Therefore, landscape diversification and organic farming may both promote invertebrate biodiversity on farmlands, but their relative role and potential interactions have rarely been investigated. The aim of this study was to determine the effects of farming practice and shelterbelts on beetles and spider assemblages on dairy farms. Six pairs of organic and conventional farms were selected. Ground-dwelling beetles and spiders were collected using a vacuum suction from underneath shelterbelts, and 10 m into pasture. Ground vegetation was monitored within 1 m2 quadrats from shelterbelts and pastures. Our results suggest that plant species richness was higher on organic farms compared with conventional ones, but not plant biomass or weed biomass. Organic farming practice increased spider densities, particularly native species, but did not influence their species richness, nor have any measurable influence on beetle communities.. Pastures on conventional farms had significantly higher density of herbivorous beetles. Habitat diversification did not influence spider density, but had a positive impact on species richness of spiders and the density of predatory and detritivorous beetles. Although direct mechanisms of predation by spiders on herbivorous beetles are not clearly established from our study, organic farming practice appears to successfully suppress pest insects by increasing the abundance of their natural enemies, such as spiders. Shelterbelts also play a key role in supporting biodiversity of beetles and spiders on dairy farms and, therefore, needs to be maintained within farm landscapes.
Dr Yuki Fukuda is a Postdoctoral Fellow in the ARGOS environment team. She is interested in increasing native biodiversity through greening production landscapes. After finishing her high school in Tokyo, Japan, Yuki completed a BSc with Honours (Ecology and Conservation) at Lincoln University. During her honours, she studied pest bird management using visual birdscarers in Canterbury vineyards. She wanted experience much richer biodiversity, so she went to the University of Queensland for her PhD. Yuki used various ecological indicators (soil, vegetation & ants) to determine the process of landscape restoration in a western Queensland national park that was previously pastoral farmland. Yuki is based at Landcare Research in Hamilton to be close to her study sites in the Waikato. She enjoys the challenge of solving ecological problems, while accommodating social and economical needs in ARGOS projects and working with the people that matter the most – the farmers.