Conditions and Trends of Ecosystem Services in New Zealand—a Synopsis

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Landcare Research
Much of the mountains and steep hill country of New Zealand remain in indigenous forest.

In Brief

New Zealand is highly dependent on ecosystems for a range of services. Since the arrival of Europeans in the 19th century, many natural ecosystems have been converted to managed ecosystems. This conversion has been accompanied by biological invasions. Managing the balance between natural and managed ecosystems is crucial. In this article, we review the conditions and trends of ecosystem services in New Zealand. We find that natural resource management is maintaining services, but there are several opportunities for enhancement. These include better matching of land use to soil capacity and improved management of riparian zones for water quality. A more systematic approach to evaluating trade-offs among invasive species and native biodiversity would also be helpful.


Key Concepts

  • In terms of biodiversity, New Zealand is a unique country with a very high level of endemicity, making it deserving of a New Zealand-relevant ecosystem service assessment.

  • New Zealand landscapes have experienced widespread change since the arrival of Māori (c. 1200 AD) and Europeans (c. 1800 AD).

  • Biological invasions resulting from Māori and European arrival continue to have major impacts on natural ecosystems.

  • Intensification of farming systems are increasing pressure on river water quality.

  • 1. Natural resource management is maintaining ecosystem services; however, there are several opportunities for enhancement.

The Millennium Ecosystem Assessment (MEA) identified many services provided to humans by nature, termed ecosystem services (ES),1 and demonstrated that these services make major contributions to improving human well-being. More recently, the Economics of Ecosystems and Biodiversity (TEEB) study advocated that ecosystem services should be measured and valued to facilitate their inclusion into decisions.2 The importance of this inclusion was first articulated by Costanza et al., who valued global ecosystem services at about 30 trillion dollars per year, that is, approximately twice the global Gross Domestic Product (GDP).3

Life is divided into six kingdoms. In order of increasing complexity, these are bacteria, protozoa, chromista, fungi, plants, and animals.4 New Zealand is a unique country in terms of biodiversity with a very high level of endemicity, that is, the proportion of unique species found nowhere else.5 For example, 81 percent of seed plants, 99 percent of the 5,000 beetles, 89 percent of 18,000 arthropods, all 29 species of stick insects and 34 species of cicada, 96 percent of 1,600 spiders, and 99 percent of 1000 species of land snails are endemic. And inside New Zealand’s extended economic zone live almost three-quarters of the world’s penguins, albatross, and petrels.

The MEA was necessarily conducted at a global scale. However, management of biodiversity and natural resources are typically carried out at national and regional scales. If we are to improve management in New Zealand through a more inclusive and direct consideration of benefits, then assessment of ecosystem services needs to be at these scales, within the context of high endemicity.

The recently published book Ecosystem Services in New Zealand – Conditions and Trends is the first assessment of ecosystem services at national and regional scales for New Zealand.6 The authors of the chapters in Part 1, which relates to particular ecosystems, were asked to characterise the ecosystem, describe fundamental processes associated with ecosystem services, and review conditions and trends. Information on other issues touching upon natural resource management was also requested depending upon the ecosystem. The authors of the chapters in Part 2, which relates to particular ecosystem services, were asked to describe the fundamental processes, review conditions and trends, and outline drivers of change. Likewise, information on other issues was requested where deemed relevant to natural resource management. This article presents a synopsis of the book. We provide perspectives on risks to services, and identify opportunities for enhancing ecosystem services.

Natural Terrestrial Ecosystems

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Landcare Research
A dairy farm in the lowlands with production forestry on the hills.

Terrestrial ecosystems in New Zealand encompass the full range of temperate vegetation types including forests, shrublands, grasslands, and dozens of naturally uncommon ecosystems such as volcanic dunes and unique geothermal communities. Indigenous forests are the most common, covering about 6.5 million hectares, equivalent to 25 percent of New Zealand’s land surface. Most indigenous forests are on conservation land and thus protected. Although there is a continuing small loss of indigenous forests on private land, this is more than compensated for by about one million hectares of indigenous shrubland regenerating back to mature forest. Tussock grasslands cover 2.6 million hectares, mostly in the South Island high country, which is characterised by extensive pastoral management and sweeping vistas. These grasslands are rich in endemic flora and fauna, but many areas are being invaded by non-native trees such as pines or Douglas fir, and animals such as rabbits, rats, brushtail possums, or stoats. While there is some ongoing conversion of tussock grasslands to exotic grassland (500 ha/yr), a tenure review process of high country farms has created 10 new conservation parks of 580,000 ha over the past decade. Naturally uncommon ecosystems are not large in areal extent but contain unique flora and fauna. Of the 72 different types, 17 are endangered, and 18 are critically endangered.7

Managed Terrestrial Ecosystems

Pastoral farming is the dominant land use in New Zealand. Sheep and beef farming occupy over 9 million ha. The climate in New Zealand favours pasture growth, which provides over 95 percent of animal feed in grazing systems. The annual value of meat and wool products is $8.5 billion (Figure 1), with $7.5 billion of that in exports. The area of pastoral agriculture has marginally declined due to reversion of marginal pasture lands to shrublands, but the efficiency of the sector has increased through improved management and technology. Dairy farming (1.6 million ha) occupies less area than sheep and beef farming, but provides $12.6 billion of dairy products, $12 billion of that in exports. Arable cropping is limited to 174,000 ha and provides $2.2 billion of food, $0.6 billion of that in exports. Horticulture occupies only 70,000 ha of land yet it generates $6.4 billion, $3.5 billion of that in exports. This high provision of income per hectare is second only to mining (Figure 2).

Planted forest occupies 1.72 million ha of land, with Monterey pine (Pinus radiata) the most common forest species. The annual value of ecosystem services from planted forests is $8.7 billion, which includes exports of $4.3 billion and important nonprovisioning services such as carbon sequestration ($250 million), avoided soil erosion ($250 million), and bioenergy ($920 million).

While urban-dwellers make up 85 percent of the population, population densities are low relative to cities elsewhere in the world. Cities are generally green, with large private gardens and accessible city parks. Most residents are able to travel by car to some kind of park in less than two and a half minutes, and most residents live within 5 km of the sea. Regulation of water quality, stormwater, flood and erosion control, waste disposal, and air quality is important in our cities. Cultural services such as recreation and sense of belonging are notably important.

Soils and Mineral Resources

Soils are a key component in ecosystems and directly provide a number of ecosystem services. Soil quality indicators monitored in New Zealand include total carbon, total nitrogen, pH, Olsen P, mineralisable N, bulk density, and macroporosity. These have been used to identify regional issues including soil compaction, organic matter decline, excessive fertility, erosion risk, and accumulation of contaminants. ‘High class soils’ are those soils that have high functional capacity for primary production and are also highly versatile. While urbanisation has long been a cause of concern for the loss of high class soils, lifestyle blocks have a greater potential to lock productive land out of future production. It has been shown that 10 percent of high class soils are currently under lifestyle block farming, with concerns over the rapid expansion of lifestyle blocks in recent years.8

New Zealand is also rich in minerals, coal, and hydrocarbons and has been a significant producer of coal and gold since early European settlement. Production has grown in the last 25 years, with peak production of coal in 2006.

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Figure 1: Gross ecosystem services in billions of dollars (y axis) for the six main managed ecosystems (x axis).

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Landcare Research
Figure 2: Gross ecosystem services in thousands of dollars per hectare (y axis) for the six main managed ecosystems (x axis).

Freshwater Ecosystems

Water quality is generally good in rivers downstream of managed ecosystems and is very good downstream of natural ecosystems. Water quality in some rivers has improved due to better treatment of effluent from cities but has decreased in some rivers downstream of intensifying agriculture. Generally, freshwater biodiversity, both fish and invertebrate, is declining.

Most rivers experience sustained water flows throughout the seasons, but in some rivers the total amount of water allocable for human use at low-flow has been exceeded. In addition to rivers, New Zealand’s lakes provide fishing, cultural, and recreational services; however, the cumulative effects of agricultural land use, particularly nutrient runoff, are causing declining water quality.

Wetlands are at the interface between terrestrial and freshwater ecosystems. They provide important habitat for many species and ecosystem services including food provision, water quality improvement, flood abatement, and cultural services. In the last 150 years, more than 90 percent of wetlands have been lost, and many of those remaining are under pressure from drainage, nutrient enrichment, and invasive plants and animals.

Saline Ecosystems

Many estuaries in New Zealand provide important fish and bird breeding habitats, and important cultural and recreational services. They process contaminants from land and fuel productivity on the adjacent coast but are coming under threat from sediment loading. New Zealand’s marine realm (defined by the continental shelf) has an area of 5.7 million sq. km, about 21 times the land area. It has one of the most diverse ranges of marine habitats on earth, with rich and mostly endemic flora and fauna. Some marine ecosystem services are very important, such as CO2 uptake and O2 production (both ~1.7 percent of global levels). The annual fish catch is worth $1.4 billion.

Regulating Services

Erosion rates in New Zealand are naturally high due to high rainfall and steep terrain. With the arrival of Europeans in the 19th century, much of the indigenous forest has been converted to pasture, serving to increase erosion even further. However, the increasing trend of erosion is gradually reversing through widespread soil conservation measures (i.e. tree planting in highly erodible areas) and scrub reversion (i.e. reversion of pasture to shrublands on marginal hill country).

Both natural and managed ecosystems have significant impacts on greenhouse gas emissions. The population of New Zealand is small at 4.4 million and consequently, the annual emission from the energy sector is comparatively low at 38 Mt CO2-eq. The agricultural sector, however, contributes another 34 Mt CO2-eq. Counteracting these emissions are sinks associated with shrublands, planted forests, and erosion. There are over one million hectares of shrublands, which are growing steadily into indigenous forest and sequester 10 Mt CO2-eq per year. Planted forests sequester 20 Mt CO2-eq per year. Soil erosion is responsible for sequestering 12 Mt CO2-eq through soil replacement and the burial of soil carbon at the bottom of the ocean. In addition to the land sinks, the ocean in New Zealand’s extended economic zone sinks 50 Mt CO2-eq per year. On balance, New Zealand is thus a net sink of greenhouse gas emissions.

Pollination by animals is a crucial ecosystem service as it underpins New Zealand’s agriculturally dependent economy. Honey bees are the most important pollinators for most commercial crops, with bumble bees becoming more commonly used. Background pollination is under stress with the invasion of the varroa mite, which has caused the demise of feral bee colonies. Other stresses to honey bees are pesticides and declining floral resources through (perversely) improved weed management.

Cultural Services

Cultural ecosystem services are very important in New Zealand. Although 85 percent of people are urban dwellers, many have strong connections to the land either through farming or through outdoor recreational pursuits. Indeed, the value of sport and recreation is over $12 billion per year. New Zealanders appreciate wild and scenic landscapes for walking, fishing, or hunting. As such, wild foods form an important cultural service. As an example, eight million snapper fish are caught recreationally each year (i.e. about two for each man, woman, and child). The tourism industry, which contributes over $6 billion to GDP, is also dependent on our scenic landscapes.

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Figure 3: Estimated trends of ecosystem services over the last two decades.

The Māori perspective of ecosystem services is more integrated than the European concept, with people and ecosystems being interdependent—people caring for ecosystems (manaaki whenua) and ecosystems caring for people (manaaki tangata). This is distinct from the western viewpoint of separating ecosystems from people.

Trends

Figure 3 highlights estimated trends in ecosystem services (over the last few decades) presented like the UK National Ecosystem Assessment.9 Trends are classified as improving, some improvement, no net change, some deterioration, or deterioration. A ± indicates where there is improvement in some areas but deterioration in others. The importance of the service (i.e. relative significance of role in providing service) is denoted by the background color, with dark green denoting high importance, light green denoting medium–high importance, cream denoting medium–low importance, and grey denoting low importance. By definition (as ecosystem services necessarily include all services), the results are multidimensional. Most services are maintained, while some are improving, and others deteriorating.

Overall, New Zealand is tracking satisfactorily, with most services being maintained and improvements to services generally balancing deteriorations. However, three services stand out with deterioration being prominent: pest regulation, pollination, and provision of natural habitat free of weeds and pests. These along with several other services offer opportunities for enhancement of the service. It is worth noting that Figure 3 represents a starting point based on the science perspectives expressed in the book. However, as with the UK National Ecosystem Assessment,9 it offers promise for developing a complete natural capital assessment through debate and discussion with a range of stakeholders.

Risks and Opportunities

The major risks and opportunities for ecosystem services in New Zealand mirror those globally, but the rate and trajectory of these changes are unique. The two major drivers of changes in ecosystems are the rapid alteration of land use and intensification of biological invasions. For example, nitrogen (N) use has doubled in the past 20 years at the national scale,10 coincident with expansion of some primary industries (i.e. dairy farming) and declines in water quality for some rivers. These risks are, however, being offset by changes in management activity and farm practices, for example, widespread fencing to exclude cattle from streams. This reduces bank erosion and thereby sediment loads to rivers, lakes, and estuaries, thus improving aquatic habitat. Stock exclusion also prevents direct input to streams of phosphorus, nitrogen, and pathogens in animal excreta. Newly fenced riparian areas for systematic planting of trees and shrubs also offer opportunities for high floral resources for bees, helping assure pollination services.

Pest regulation is one service under stress. New Zealand is one of the most profoundly invaded places on earth, with more than half of the plant species currently non-native, and several hundred of these considered to be environmental weeds. To counteract invasion, the number of agents released for biocontrol of weeds has increased in the last 30 years. These releases have had some success, with partial control (heather – Calluna vulgaris) and sometimes even complete control (mist flower – Ageratina Riparia) of weeds. Conversely, pest animal species such as rabbits, rats, brush-tailed possums, deer, and pigs are enduring features in New Zealand and have novel effects on ecosystems because there are no functionally similar native species. Because of the number, abundance, and perceived impacts of these non-native species, pests and weeds are a major focus of both research and management efforts. Important progress has been made in pest animal management, for example, through extirpation of invasive rats or larger mammals from increasingly larger off-shore islands. On the other hand, many long-established invaders such as scotch broom, wilding conifers, and some invasive mammals continue to increase in both abundance and distribution.

More recently, interest is growing in whether pest management has implications for mitigating the impacts of non-native species in ecosystems and the services they provide. This has driven a shift from elimination of individual invasive species as the primary objective, towards consideration of the additional consequences or benefits that weed or pest animal management has on services. As a consequence, a larger-scale ecosystem view is emerging in which conflicts and potential trade-offs among invaders, native diversity, and services are being considered.

A Shifting Paradigm for Resource Management?

The uniting narrative in this book highlights the importance of considering the full range of ecosystem services to ensure effective natural resource management. The monetary valuation of ecosystem services in dollar terms provides a common currency for comparing services and offers a way of incorporating all the dimensions of services within management and policy decisions. Research is ongoing to improve valuation methods and ensure a clear understanding of linkages and interdependencies between natural capital stocks and flows of services. Patterson and Cole have initially estimated the total net value of ecosystem services to be approximately $60 billion per year by summing the net use value and passive value for a national stratification of 14 ecosystems.11

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Ida Kubiszewski
While most services in New Zealand are tracking satisfactorily, there remain several opportunities for enhancement of services.

The Genuine Progress Indicator (GPI) is growing in acceptance as an alternative to GDP. It encompasses a broader perspective of human well-being, taking into account depletion of natural capital and uses principles on use and nonuse value of natural ecosystems. In New Zealand, GDP has doubled in the last 30 years, while GPI has only increased by a half.

Better matching between land use and soil type is necessary for a sustainable future. New software tools have been developed to help determine optimal matches.12 They are able to determine what land use configuration maximizes objectives of ecosystem services within constraints of plausibility. For example, Herzig et al. showed that better matching of land use with soil type could reduce environmental impacts while maintaining food production in several land-use systems.12These tools can also be used to identify remaining headroom for increased agricultural production within environmental limits.

Land-based ecosystem services in New Zealand are estimated to be worth $60 billion per year (Chapter 3.2), equivalent to 30 percent of GDP. Although this proportion is somewhat smaller than the equivalent global figure of 200 percent estimated by Costanza et al.,3 the figure is still high and highlights the importance for considering ecosystem services in natural resource management in New Zealand. The synopsis of the book Ecosystem Services in New Zealand – Conditions and Trends presented here is very brief and touches only lightly on many detailed chapters. While it may point the way to some rapid gains and key issues at play, the long-term management of natural resources in New Zealand is best undertaken on a firm foundation of science-based knowledge. We therefore recommend readers consult relevant chapters of the book as needed.

Acknowledgements
The material presented in the synopsis has come from the book Ecosystem Services in New Zealand – Conditions and Trends. As such, we are indebted to the 118 authors. Senior authors of chapters come from the institutions AgResearch, Geological and Nuclear Sciences, Institute of Environmental Science and Research, Lincoln University, Massey University, National Institute of Water and Atmospheric Research, New Zealand Institute of Economic Research, Plant and Food Research, Scion, University of Otago, and Landcare Research.

Disclaimer
Although based upon the book written by 118 authors, who have been consulted with regards to Figure 3, the overall perspective of condition and trends presented here is the personal opinion of Drs Dymond, Ausseil, Peltzer, and Herzig. This opinion does not necessarily represent that of Landcare Research, nor of the institutions mentioned in the acknowledgements.