What is Biodiversity? - The University of Auckland

The Importance of Ecosystems

Sustainability, biodiversity, eco this and eco that. We’ve all heard these words so often they’ve become clichés but what do they actually mean and why does science increasingly see them as important concepts? Likewise we’re all familiar with the clean green image that is used to market New Zealand overseas. But is this image really justified? What impacts are agriculture and other human activities having on New Zealand ecosystems? Should we be worried? Is New Zealand agriculture and horticulture capable of meeting the environmental and economic demands of the 21st Century?

Questions like this are at the heart of research being carried out by the Bio-Protection Research Centre at Lincoln University. The Centre’s goal is to lead a shift away from pesticides to control pests and towards fully sustainable productive ecosystems for New Zealand's plant-based primary industries.

To be able to answer the questions at the start, we need to understand the importance of ecosystems to the functioning and survival of human societies.

Ecosystems provide us with goods such as fuel, timber, food for humans and domesticated animals and pharmaceutical products. What many people don’t appreciate is the importance of ecosystems in providing fundamental life-support services. These include the purification of air and water, detoxification and decomposition of wastes, regulation of climate, maintenance and regeneration of soil fertility and the lessening of the impact of droughts and floods (1).

Historically, society has tended to undervalue the importance of the functions provided by ecosystems, yet our survival depends on them. Therefore, understanding how to maintain healthy ecosystems is of vital importance and the reason behind the establishment of the Bio-Protection Research Centre.

This increasing awareness has led to the development of the concept of Ecosystem Services - the range of benefits that humans obtain from ecosystems that sustain and underpin life. They are sometimes called environmental or nature’s services. Ecosystem services can be categorised according to their function - Provision, Support, Regulation and Culture (Figure 1).

Increasingly ecosystem services are being assigned a monetary value as a way of measuring and comparing their contribution to our society and the impact of human activity on ecosystems and their ability to continue to deliver the services.

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Improving Ecosystem Services

Research at the Bio-Protection Research Centre has focused on increasing biodiversity in and around vineyards and pastoral farms with the goal of significantly increasing the variety, quantity and quality of ecosystem services provided, including the biological control of pests and diseases.

Deputy Director of the Centre, Steve Wratten is particularly interested in improving conditions for natural enemies by using Conservation Biological Control (CBC) - the management of pests by modifying the environment to encourage the presence of natural enemies.

Conservation Biological Control can potentially improve farm profitability by increasing yields as pest damage is reduced. Profitability increases due to a reduction in pesticide use therefore lowering costs without loss of yield, and increased demand for the product due to reduced levels of pesticide residues. There is a further benefit from public perception of a healthier environment.

How do you go about improving conditions for natural enemies? Steve uses the acronym SNAP to summarise the four key factors that natural enemies need: Shelter, Nectar, Alternative food and Pollen (Figure 2). By providing food and habitat sources for beneficial species, biodiversity is boosted and hopefully the numbers of natural enemies are increased.

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Biodiversity

Biodiversity delivers ecosystem services. If biodiversity changes then this can affect ecosystem processes such as primary production, nutrient and water cycling, pollination, pest and disease control as well as soil formation and retention. Increased biodiversity is correlated with stability of ecosystems and lower rates of ecosystem collapse and extinction of species.

Biodiversity is the variety of living organisms from all sources, including terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part. This includes diversity within and between species and of ecosystems. Biodiversity also includes diversity at multiple scales of biological organisation (genes, populations, species, and ecosystems) (3)

The changes in biodiversity caused by human action have been more rapid in the last 50 years than at any other time in human history. We are now in a situation where virtually all of earth’s ecosystems have been changed in some way by human activity. One of the main causes of loss of biodiversity is the conversion of land to agricultural use. More land was converted to farmland in the 30 years after 1950 than in the 150 years between 1700 and 1850. One quarter of Earth’s land surface is now cultivated (3).

The expansion and intensification of agriculture has occurred in response to demand for food and fibre from an increasing world population but at the cost of the ability of ecosystems to provide ecosystem services. Modern agricultural ecosystems tend to be large-scale monocultures (the production of one crop over wide areas with high inputs of fertilisers, pesticides and water). This lack of biodiversity is associated with low provision of ecosystem services. Figure 3 shows a natural ecosystem and an agricultural ecosystem. Look closely at the pictures and think about the differences between these ecosystems in, for example, their food webs.

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References and Acknowledgements

1. Daily, G. C., Alexander, S., Ehrlich, P. R., Goulder, L., Lubchenco, J., Matson, P. A., et al. (1997). Ecosystem Services: Benefits supplied to human societies by natural ecosystems. Issues in Ecology 2, 1-8.

2. Barnes, A. M., Wratten, S. D., & Sandhu, H. S. (2009). Harnessing biodiversity to improve vineyard sustainability. Outlooks on Pest Management, 20, 250-255.

3. Millennium Ecosystem Assessment. (2005). Ecosystems and human well-being: Synthesis. Washington, DC: Island Press.

4. Ministry for the Environment. (2019). Environment Aotearoa 2019. Wellington: Ministry for the Environment.

Photos and diagrams are from Steve Wratten, The Bio-Protection Research Centre , i-Stock or LENScience, unless otherwise stated.

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