Project reference: 2001-03
Are Plantation Forests with Increased Biodiversity More Resistant to Pest Outbreaks?
Project description:
Background
Biodiversity is of increasing relevance to the sustainable management of plantation forests. The Montreal Process, recent Government policies, and the certification of plantations, mostly through the Forest Stewardship Council (FSC), require attention to biodiversity issues beyond the conservation estate (Brockerhoff et al. 2001). A different aspect of biodiversity relates to plantation ecosystem functioning, and this has received very little attention so far. An exciting question is whether promoting biodiversity in plantations could help to prevent outbreaks of pests such as defoliating insects.
Defoliators such as the European pine shoot moth (which gobbles up Chile´s radiata plantations) and the nun moth (a close relative of the much-feared gypsy moth) pose a great biosecurity threat to our plantation forests. Occasionally, native defoliators have caused considerable damage to plantations. For example, the native looper Pseudocoremia suavis had outbreaks in the 1950´s in pine plantations in Canterbury, and in the early 1970´s in Douglas-fir stands in Kaingaroa Forest (Alma 1977). Although our knowledge of the population dynamics of the native defoliators of pines is limited, predators and parasitoids are likely to be important. Plantation forests are akin to agricultural ecosystems in that they are usually less diverse than native ecosystems and may be unsuitable as habitat for natural enemies. Because of this, they could be less resistant to pest problems. Applied ecologists are increasingly aware of this and promote habitat management to create agricultural environments that are more favourable to natural enemies (Landis et al. 2000).
Objectives
We propose to examine whether there are relationships in New Zealand pine plantations:
(1) Between the diversity of understorey plants and the diversity of predators (ground beetles) ---andparasitoids (parasitic wasps), and (2) Between the diversity of plants / natural enemies and the abundance of defoliators of pines.
Methods, research team and funding
To address these questions, a replicated study will be carried out in young and mature radiata pine stands. Understorey plant diversity will be assessed with the Recce plot method. The abundance of defoliators will be determined by collecting caterpillars of common looper and tortricid defoliators and by trapping adult moths using pheromone traps. (Potential target species are Pseudocoremia suavis, Ctenopseustis obliquana and Planotortrix notophaea; the selection will depend on their occurrence at the study sites.) We will collect ground beetles by using pitfall traps, and parasitoids by rearing and dissecting caterpillars.
This is a collaborative project between Eckehard Brockerhoff and Chris Ecroyd of Forest Research and Herve Jactel of INRA, France, who works on similar research in French pine plantations (e.g., Jactel et al. 1994) and will spend about one year in New Zealand on a sabbatical visit. INRA and the French Government provide funding for the sabbatical (salary for Dr. Jactel and travel to NZ). New Zealand staff are mostly covered through our FRST funded research on plant and insect diversity in plantations. We are seeking additional support from the Forest Health Research Collaborative to cover local costs including technical assistance, equipment and field trips.
Outputs / outcomes
The results will be published in a NZ forestry journal (e.g. NZ J. of Forestry). Dr. Jactel will also be available to give a presentation to the FHRC on his research on insect pest problems and biodiversity in French pine plantations
Research Provider:
Forest Research
National Institute for Agricultural Research (France)
