Grant Blackwell

Intensification of New Zealand agriculture: Implications for biodiversity

Abstract Intensification of New Zealand agricultural practices is an ongoing and accelerating process which potentially threatens the environment, biodiversity and even the sustainability of agricultural production. However, neither the exact nature of this threat nor the extent of its impact has received adequate analysis. There is clear evidence that agricultural intensification has degraded aquatic biodiversity, but there is a critical lack of research and monitoring of robust indicators of terrestrial biodiversity in New Zealand production landscapes. Therefore, we can only infer a generalised likelihood that intensification has also reduced terrestrial biodiversity and agro‐ecosystem resilience. It is unknown whether biodiversity and ecological services provided by the actual land growing crops, pasture or wood fibre are degrading because of intensification. Increased use of ecological subsidies (nutrient and energy inputs) may have compensated, at least in part, for the increased rate of food production (nutrient and energy outputs). Lasting practical solutions to enhance sustainability can only be identified by long‐term transdisciplinary research of ecological disturbance in agro‐ecosystems. Working with intensification to identify environmental and social gains at the same time as capturing economic efficiencies is more likely to support biodiversity than simply attempting to stem or reverse intensification. A change in world view of both rural and urban dwellers, from the predominant philosophy that allocates land to either preservation or production to one that promotes sustainable land‐use practices that integrate extractive resource use with conservation, is the key to mitigating impacts of agricultural intensification in modified landscapes.

Pathways for integration of biodiversity conservation into New Zealand's agricultural production

Our claim that integration approaches will be more effective than land allocation approaches for conserving biodiversity in New Zealands agricultural production landscapes (Moller et al. 2008b) has been challenged by Lee et al. (2008, this issue). Our critics also disagree with our conclusion that ongoing intensification is inevitable and assert that it must be counteracted if New Zealands globally

Social‐ecological scales and sites of action: Keys to conserving biodiversity while intensifying New Zealand's agriculture?

1 The Forum section contains short opinion articles on topics within the scope of the New Zealand Journal of Agricultural Research. Forum articles are not refereed, and editing is limited to style matters. They should be no more than the equivalent of 2500 words including references. Articles commenting on a specific paper will be referred to the author(s) of that paper for right of reply before publication. Forum articles should not be cited as scientific papers.

Abundance and diversity of herbaceous weeds in sheep/beef pastures, South Island, New Zealand

Abstract This study compared species diversity, abundance and size of broad-leaved herbaceous weeds on 28 South Island sheep/beef farms that employed either organic, integrated management (IM) or conventional management (CM) systems. Three or six paddocks per farm were surveyed using walked transects in November 2005, and the presence and number of individuals of each weed species encountered were recorded. 39 broad-leaved herbaceous weeds were recorded on all the farms in the study, but 76.7% of occurrences were of just three species (Californian thistle (Cirsium arvense L.), dandelion (Taraxacum officinale) Weber and daisy (Bellis perennis L.)). The ten next most abundant species made up 21% of records and the remaining 26 species just 1.9%. Very few significant differences were found in the geographic distribution, species richness or Shannon diversity index, abundance, cover or size of broad-leaved herbaceous weeds present on farms employing the different management techniques. However, there were significantly fewer Californian thistle per m2 on CM than on organic or IM farms and cover of all herbaceous weeds averaged 5.0, 5.6 and 2.1 on organic, IM and CM farms, respectively. Weed infestation varied enormously by region and between individual farms, so the statistical power of the comparisons was relatively low. Until further research is reported, the authors caution against general and unquantified assertions that the sustainability of organic pastoral farming is, or is not, compromised by weed infestations.