Intensification and diversification of New Zealand agriculture since 1960: An evaluation of current indicators of land use change

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Abstract

Previous studies of New Zealand's environmental and agricultural history have provided a broad-brush characterisation of land use change that potentially misses pivotal fluctuations in land use policy and practice that would inform us of key drivers of ongoing agricultural land use change. Of particular interest to policy makers is the period after the end of agriculture's ‘long boom’ in the late 1970s, when a dramatic change in economic policy occurred and farming subsidies were removed. A review and principal components analysis of 35 New Zealand agricultural statistics from the past 40 years identified two main patterns of change in land use, production, and farm inputs. One set of variables, which explained 49% of the variation, indicates an overarching, strong and steady trend for agricultural intensification and to a lesser extent diversification, as indicated by (a) increasing stocking rates and yields, (b) increased farm fertiliser, pesticide and food stock inputs, (c) conversion to more intensive forms of agriculture, and (d) diversification into forestry and deer farming. A second group of variables, which explained 22% of overall variation, inflects around 1982/1983, the time of a major shift in agri-economic policy that removed farm subsidies. The second group of changes included some contraction in agriculture (especially in sheep farming) and its associated inputs and a decline in rural population. There is evidence of acceleration in intensification and diversification in the past decade and for slowing in the contraction of the second set of variables between 1997 and 2001. The drivers of these changes are poorly understood and their impacts on biodiversity conservation in farmed landscapes cannot be discerned from the national indicators currently being monitored. The accelerating agricultural intensification over the past 40 years raises concern about whether New Zealand farming is broadly ecologically sustainable now, and especially whether it could remain so in future.

Introduction

New Zealand's species-rich lowland ecosystems have been dramatically modified by several significant changes in land use since the arrival of humans (MfE, 1997, Norton and Miller, 2000). Alluvial floodplain forests, fertile wetlands and indigenous grasslands are now largely replaced by agricultural landscapes pre-dominately pastures of introduced grasses and clover Trifolium spp. The agricultural sector plays a key role in influencing New Zealand's economy and society, with agricultural-based products currently representing about 53% of merchandise exports (Ballingall and Lattimore, 2004, Statistics New Zealand, 2004).

Modification of lowland and montane forests began between 750 and 500 years ago when an increasing Polynesian population used fire to clear the land for agriculture (McGlone, 1989). This was followed by more rapid and dramatic modification of the landscape upon the arrival of European settlers in the early 19th century (Aitken, 1944, Molloy, 1980, MfE, 1997, Norton and Miller, 2000). Between 1900 and the mid-1970s, the portion of New Zealand covered by agricultural land and exotic plantations increased from 35% to 60% (Molloy, 1980). Five major phases of agricultural development have been categorised for the period between 1840 and 2002: colonisation, expansion, early intensification, diversification, and later intensification (Molloy, 1980, Langer, 1990, Glasby, 1991, PCE, 2004).

During the colonisation phase (1840–1870), large areas of indigenous grasslands were burnt for grazing and the sheep population increased dramatically (Molloy, 1980, Langer, 1990). These ‘unimproved’ grasslands were quickly depleted because energy inputs to the system were minimal, and sheep numbers declined. The introduction of refrigerated shipping in 1882 led to an expansion phase driven by rapid removal of indigenous forest and expansion of permanent pasture (Molloy, 1980, Langer, 1990).

The early phase of intensification began around 1920, facilitated by the application of new soil science, fertilisers, and improvements in plant and animal breeding. Between 1920 and 1970, the area of sown pasture remained fairly stable but the number of stocking units increased by about 150% (Molloy, 1980). At the same time, national meat and dairy productivity doubled and wool production tripled (Langer, 1990). However, it is unclear how long this early phase of intensification lasted. Some reports suggest that it ended in the late 1940s (Glasby, 1991, PCE, 2004). Others indicate that the rate of intensification increased after World War II (Molloy, 1980) and continued until as late as 1970 (Molloy, 1980, Langer, 1990).

Similar disparities are reported for the starting date and duration of the next phase of agricultural development, diversification (Molloy, 1980, Langer, 1990, Glasby, 1991, PCE, 2004). There was probably at least some overlap between the early intensification and diversification phases. For example, farmers were able to develop infertile hill country land because the introduction of aerial top dressing in the late 1940s enabled them to fertilise previously inaccessible areas (Molloy, 1980, Langer, 1990). During this phase, the agricultural sector diversified from the traditional sheep and cattle farming to include deer, goats, horticulture and agroforestry.

A later phase of intensification is thought to have started in the 1980s and continued to the present day (PCE, 2004). Certainly, there is evidence of a general trend for more intensive farming systems in the last 10 years (PCE, 2004).

The foregoing broad-brush characterisation of New Zealand's environmental and agricultural history potentially misses pivotal fluctuations in land use policy and practice that would inform us of key drivers of ongoing agricultural land use change. In particular, there is a lack of a published synthesis of various agricultural land use and production statistics since the end of agriculture's ‘long boom’ in the late 1970s. The period is of particular interest to agricultural policy makers because dramatic changes in economic policy, broadly characterised as removal of farming subsidies, were imposed in the early and mid-1980s (Dalziel and Lattimore, 2004). This review attempts a broad-ranging quantitative review of New Zealand agricultural statistics for the 20 years before and after this shock. Our primary aim was to better categorise periods and trends in New Zealand agriculture, but also to consider whether intensification and diversification is accelerating, and how long the agricultural reforms of the 1980s impacted on national-level agricultural statistics.

Over the last few decades in New Zealand, there has been considerable debate about how farming can be conducted to maintain natural capital as well as social well being and economic viability (PCE, 2004). The Ministry of Agriculture and Forestry has, therefore, defined ‘sustainable agriculture’ as: ‘… the use of farming practices which maintain or improve the natural resource base of agriculture, and any parts of the environment influenced by agriculture. Sustainability also requires that agriculture is profitable; that the quality and safety of the food, fibre and other agricultural products are maintained; and that people and communities are able to provide for their social and cultural well-being.’ Our secondary aim was, therefore, to evaluate the utility of the available data and identify gaps in knowledge for future monitoring as part of a more widely ranging review of whether New Zealand is sustainable now and will remain so in future.

Our review complements the recent research of the New Zealand Parliamentary Commissioner for the Environment (PCE, 2004), which examined the environmental sustainability of more intensive farming in New Zealand. The PCE report focused primarily on land use change and collated fragmentary data on management practices within individual sectors mainly during the last decade (Table 1). By searching for national trends in fewer agricultural statistics but over a longer period we sought to put the findings of the PCE into a more historical perspective and assess the agricultural reform impacts. Elsewhere, we will consider potential impacts of agricultural intensification on New Zealand's biodiversity and challenge current conservation priorities in New Zealand.

Section snippets

Methods

Annual data for 48 agricultural variables for the period 1960–2002 were derived mainly from the Statistics New Zealand's annual reports on New Zealand Agricultural Statistics and the FAOSTAT database (http://faostat.fao.org/faostat). Appendix A lists the agricultural variables, data sources, and the years that data were available. Changes in the number or type of data presented by Statistics New Zealand in some years meant that some annual estimates were missing for some variables. For each

Areas of different land uses

The total area of land classified as occupied for agricultural use in New Zealand is reported very differently by our two main sources of data for this review (Fig. 1a). According to the New Zealand Agricultural Statistics database, the total area of land increased by 20% (0.92% per annum) during the 1960s and 1970s (Fig. 1a), but then declined again over the next 20 years (−1.48% per annum) to such an extent that the occupied area in 2001 was 10% lower than in 1961. However, the rapid step up

Evaluation of agricultural indicators used in this review

The indicators used in this review are coarse and can only monitor changes in agricultural management at the national scale. Agricultural activity and the impact of land management practices on local rural communities and biodiversity will depend on a number of factors acting at different scales, i.e. national, regional, farm and field levels (Benton et al., 2003). For example, the nature and extent of historical land use change may have varied significantly between regions.

The national

Conclusion: Is New Zealand agriculture sustainable?

Our review highlights the overall and relentless nature of agricultural intensification over the past 40 years. Coarser indicators emphasise that this intensification has proceeded at least for the 80 years before the period we have reviewed (Molloy, 1980, Langer, 1990, Glasby, 1991). Some of the indices of intensification involve increased inputs to the agroecosystem (especially fertilisers and water, but recently also livestock foods) and these may partially or wholly compensate for the

Acknowledgements

We are grateful to Grant Blackwell, Tom Brooking, Richard Duncan, John Fairweather, Julia Haggerty, Jon Manhire, Chris Rosin and three anonymous referees for commenting on an earlier draft of this manuscript. We thank Sean Bithell, Dan Chamberlain, Bill Griffin's research team, Neil Gow, Nick Pyke and Jack Richardson for helpful discussion in the initial stage of this project. This work was partly funded by a Landcare Research Hayward Postdoctoral Fellowship awarded to CJM. HM's work was funded

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