28 June 2011

Life is a Garden, Dig it- and plant some green manure while you’re at it!




This article was prepared by postgraduate student Scott Sharp-Heward as part of the ECOL 608 Research Methods in Ecology course.

New Zealand: land of the long brown dairy farm. Or at least it sometimes feels like that, what with the proliferation of dairy farming over the last 10-15 years. This typically intensive farming method is often associated with loss of biodiversity due to removal of natural habitat and food sources for endemic species. However, one of the largest and most varied reservoirs of life, the soil, is often not taken into account when examining the effects of farming practices. This seems like a huge oversight when the pesticides and fertilisers being applied in conventional agriculture are likely to directly affect soil-borne life. In contrast to this, organic farming often concentrates on soil microbial health to a great extent, something which can be seen in such international organisations as Soil Foodweb. It is often thought that organic farms have a much wider diversity and larger amount of microbial life in soil than conventional farms, but is this truly the case?


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Christine Stark, Leo Condron and their team at Lincoln University sought to address this question by carrying out a study on the links between soil microbial properties and agricultural production systems. In particular, the effects of long term land use management and short term land use practices on soil microbiology were studied.






So why care about microbial diversity and abundance in soil? Well, as any keen So why care about microbial diversity and abundance in soil? Well, as any keen gardener will tell you, earthworms are indicators and facilitators of fertility in soil; they are present in healthy conditions and help turnover nutrients in soil so they can be used by plants. Soil micro-organisms are the same; even though they may be invisible to the unaided human eye. Micro-organisms are working constantly by breaking down and consuming nutrients that aren’t available to plants and excreting nutrients which are. If there were no micro-organisms in soil there would be no break-down of dead material and hence no new nutrients for plant growth! These micro-organisms include filamentous fungi, bustling bacteria, predatory protozoa, and ancient archaeans (some of which are seen in the picture on the right). It is good to have a diverse bunch of these different micro-organisms as they all occupy their own unique position in the soil food-web and will be adept at breaking down different things.






In this study performed at Lincoln University, soil taken from two farms of different long-term management types (one conventional farming, one organic farming) had different nitrogen fertiliser treatments applied to examine the effect on soil life. These fertiliser treatments included use of an organic form of nitrogen (green manure lupin) and use of an inorganic form of nitrogen (urea fertiliser). It was found by Dr. Stark and her colleagues that while there was slightly greater microbial life to begin with in the organically farmed soil, it was not statistically greater, so it was concluded that there was no major difference in soil life between the long-term farm management types. However, when it came to getting a response from the soil micro-organisms from the different types of nitrogen fertiliser that were applied, the green manure lupins stimulated not only a massive increase in both soil microbe population but also in diversity- even in conventionally farmed soil! This was in stark contrast to the Urea fertiliser which didn’t elicit any response in the soil microbial community when applied.






So the results are clear- if you want soil with a bustling microbial population, make sure you till plant matter back into the soil and grow a green manure crop whenever you can!






Stark, C., Condron, L.M., Stewart, A., Di, H.J., O’Callaghan, M. (2007). Influence of organic and mineral amendments on microbial soil properties and processes. Journal of Applied Soil Ecology Vol. 35 Iss. 1, pgs 79-93.













24 June 2011

Kiwi vision: the blind side

This article was prepared by postgraduate student Mortiz Schmid as part of the ECOL 608 Research Methods in Ecology course.


Photo by Kerry-Jayne Wilson, Lincoln University.


One of the basic principles of vision is that an eye which is supposed to maximize information gained at low light levels needs to be large. Information is gained through two cell types in the eye (cone cells for colour vision and rod cells for contrast) that detect and convert light into electro-chemical signals that can be processed by the brain structure. This poses a particular problem for nocturnal (active at night) flying birds since they need huge eyes in order to compensate for the low intensity of natural light and unfortunately large eyes are heavy. To be able to fly, there is always selective pressure (traits that are favoured by evolution) among birds to reduce their overall body mass.


What about kiwi?
We would think that as a nocturnal bird that is not subject to the mass constraints of flying, Kiwi would develop huge eyes. But they didn’t. This brings into question: Why?

Graham Martin, Professor of Avian Sensory Science, at the University of Birmingham and Kerry-Jayne Wilson, who has recently retired from Lincoln University in conjunction with J. Martin Wild, Stuart Parsons, M. Fabiana Kubke, Jeremy Corfield, investigated this paradox.

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The researchers looked at the eye, brain and bill structure and measured the visual field (the part of the sphere around the head the bird is able to see, Fig. 1) in two species of Kiwi. They discovered that Kiwi rely minimally on their visual sense, instead relying more on their olfactory (what they smell) and tactile (what they touch) senses. This situation is similar to some nocturnal mammals, but Kiwi and nocturnal mammals evolved these features independently. The researchers propose that the visual system of Kiwi has undergone an adaptive regressive evolution, meaning that through evolution, they have lost a highly developed visual system in favour of the other senses which became more developed. This regressive evolution may have been driven by the trade-off between the low amount of visual information that can be gained at low light levels and the energy costs of the processes involved.

Each structure that was investigated pointed clearly towards a bird that relies mostly on its olfactory and tactile senses, but not so much on its visual sense. On the one hand, the overall eye shape of Kiwi was similar to birds which are active during daylight. The visual field of Kiwi are the smallest yet reported, with a very small binocular area (where both eyes can see something), a relatively small monocular area (visible with one eye) and a very large area in which there is no vision, the blind sector. Comparison with three different species (Barn Owl, Emu and Pigeon) showed that Kiwi have by far the smallest optic nerve diameter (which transmits information from the eye to the brain) and the area of the brain devoted to visual information is virtually absent in Kiwi while they are very large in the other species. On the other hand, the nostrils of Kiwis are right at the tip of the bill. Here, there is also a high concentration of mechanoreceptors which detect mechanical cues that are produced when the bill touches something. In addition, brain centers representing tactile and olfactory processing are well developed. This information supports the idea that the bill is the focus for gathering olfactory and tactile information. Regarding the close relationship between Moa (with large eyes) and Kiwi (with small eyes), it seems plausible that the evolutionary step that led to a reliance on olfactory and tactile cues, which happened in Kiwi, was caused by the low light level on the forest floor. Where the costs of maintaining a visual system adapted to low light intensity was higher than the benefits which were gained by relying on olfactory and tactile cues. Here, the scientists were able to reveal this very important principle regarding kiwi vision which now can be included in all kinds of kiwi recovery projects and makes for a new perspective in kiwi habitat management.

17 June 2011

Bringing nature (back) into cities...

This article was prepared by postgraduate student Cynthia Resendiz as part of the ECOL 608 Research Methods in Ecology course.

“Canterbury plains are one of the worst examples of the loss of native plants in New Zealand...less than 0.5% of native vegetation remains on our plains”, New Zealand’s Spellerberg, a Lincoln University scientist, said in a blog interview in 2010. Trees that live in cities come from different parts of the world; however, not all trees are suitable for all environments. Each species has special requirements to grow successfully, but native trees are already adapted, and they are a good choice for urban spaces.

We need trees in cities. Trees, especially native species, have many functions and values, producing economic, social and environmental benefits. They can provide us with goods and services such as: improving air quality, recreation, saving energy, and ornamentation.

The kind of trees found in a city depends on public preferences, planning decisions and even historical reasons. There are many areas in cities reforested with new trees, but mainly using non-native trees. Particularly in New Zealand, due to the historical influence of the United Kingdom, urban trees are chiefly non-native, and often from the northern hemisphere.

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The use of exotic trees is becoming old-fashioned. There is a global tendency to plant native trees. For example cities such as Adelaide in Australia or Warrington New Town in United Kingdom are implementing programs to redress the loss of native vegetation.

Many scientific studies suggest that native trees are the best option for cities. One of these studies was published in Landscape Review by Ian Spellerberg in 2008. He highly recommends planting native trees and gives the following criteria for choosing trees:
• Besides an aesthetic and functional tree, we need to think carefully about why we need a tree and where it will be planted. We must have in mind that this is a long-term decision.
• The genetic origin of the plant is important, particularly when it is a indigenous tree. We should ask for native species grown from seeds from the local area (eco-sourcing).
• Try new species, especially trees indigenous to your area. These kinds of trees have low maintenance requirements. This is important because life in cities is busy and you should not have to worry about your tree. If you are living in Canterbury, the organizations Trees for Canterbury or Motukarara Conservation Nursery may help you to make your choice.
• Learn about possible nuisance factors. This involves safety and structural problems. Sometimes trees can cause health problems (i.e. allergies). Also the anatomy of the tree can bring problems to houses and people (e.g. root spread can damage pipes).
The diversity of species and ages of trees are important. It is recommended to have patches that include a mixture of them.

We should be proud of New Zealand’s natural heritage. Planting native trees contribute to conserve genetic resources that are exclusive from New Zealand. This will attract native wildlife, such as native birds, providing sources of food and habitat.

“I think New Zealand’s more precious natural heritage are native plants. Therefore, we should celebrate native plants by having a native only policy for urban areas” – Ian Spellerberg said in May 2011.

Given these points, the decision around planting a tree is very important and must be taken carefully, because it is an investment for the long term, which can bring us invaluable benefits. Your tree must be adaptable to urban conditions, otherwise we can get the opposite result, and the tree can bring us problems. Buying a tree seems simple, but it is an important decision that can contribute to nature conservation. Next time, look at the trees growing around you, and think about what kind of tree you would like to plant.

Kind regards John Maillard for the photo of Ian Spellerberg

15 June 2011

Quake


Two large aftershocks hit the Canterbury region yesterday (a 5.6 at 1pm and a 6.3 at 2.20pm). They were extremely unpleasant to be in on the 5th floor of Ecology! The building got a real sway on. The university was evacuated as a precaution and was shut today while buildings were inspected. Apart from liquefaction in areas close to Lincoln, there was no obvious problems with the university and township. We are up and running again today (15th June).


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09 June 2011

A Burning Issue for Magpies

This article was prepared by postgraduate student Laura Hollerbach as part of the ECOL 608 Research Methods in Ecology course.

The Azure-Winged Magpie (Cyanopica cyanus) occurs over wide parts of Asia and Iberia. The species, unhesitatingly described by Haojin Tan (Jin) as “pretty loud and noisy” has been studied throughout its range but most recently a population in Northern Mongolia has been researched. Jin has spent two summers following these birds around watching how they adapted to the aftermath of a fire in 2009. The fire was human-induced and devastated 70,000 ha of wood- and grassland.
Jin recently completed her Lincoln University thesis on habitat use and population dynamics of the Azure-Winged Magpie and their response to fire in Northern Mongolia.

The Azure-Winged Magpie is a cooperative breeder, meaning that mainly non-breeding individuals help the breeding pair rear their chicks. Both sexes are similar in plumage and size - they have a black hood and pale blue wings and tails. The magpies mainly feed on invertebrates, seeds and fruits and live in social flocks. They lay five to nine eggs between April and July which are incubated by the females.

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Jin conducted her fieldwork in Khonin Nuga, which is a valley in the West-Khentey region of Northern Mongolia. She was based in the research station of Georg-August University Göttingen (Germany) that was established in cooperation with the National University of Mongolia in 1997. The Khentey Mountains where the Siberian forest (also referred to as Taiga) meets the steppe are still widely untouched by humans.

Jin located a 1.2 km2 home range for “her” colony with six areas utilised by the birds, one of which was particularly preferred. The preferred area was least affected by the fire and was characterised by having the densest, protective Padus asiatica shrub and the highest diversity in other plant species utilized by the magpies. The birds seem to have expanded their home range after the fire, which can possibly be explained by food availability being affected by the catastrophe.

In order to analyse population dynamics, Jin obtained data collected over a four-year period (2006-2009) from previous studies on the same colony. She found that over the years the colony size at the beginning of each breeding season was constant. However, the number of chicks that hatched and fledged declined significantly, and the adult survival rate decreased. This might be explained by the harsh winter and the fire during the study period. A constant juvenile survival rate is possibly associated with intensified helping behaviour after the fire. Jin found that the colony was an open population, meaning breeding with other populations occurs. The proportion of breeding adults was 26-67%, and one quarter of the females abandoned the partners they bred successfully with and approached a new male between breeding seasons.

Jin is about to finish her Master’s degree in “International Nature Conservation”. This degree is jointly offered by Lincoln University and Georg-August University and includes one semester at each university and a compulsory internship semester that provides an opportunity to work in a practical project anywhere in the world. The last section of the degree involves writing the master thesis.
“It was very hard work”, Jin admits, yet with a smile on her face. For Jin, working in Mongolia was a precious experience that provided her with a unique insight into the Mongolian culture. “It was interesting to learn about the Mongolians’ perspective on life. They are not hurried and solve problems on a day-to-day basis. You don’t find that any more in the developed world.” She also enjoyed the transportation which was riding the horse to work every day: “That’s something most people will never get to do in their lives.”

“After having finished my thesis I have more questions about the topic than before”, Jin laughs. Further research is required to identify long-term effects of fire on the colony.



This article was prepared by postgraduate student Laura Hollerbach as part of the ECOL 608 Research Methods in Ecology course.


02 June 2011

Voice Hears His Calling – An Interview with David Voice, Graduate of Lincoln University

David Voice is an entomological scientist at the Ministry of Agriculture and Forestry in Christchurch, New Zealand; he completed a Master of Applied Science under the supervision of Bruce Chapman at Lincoln University in 2000. His thesis was done through the entomology department on insecticide resistance in offspring of crossed diamond backed moths. Juliane Diamond, ECOL 608 student, interviewed him to get his opinion on the program and the relevance it had to his career.
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Why did you decide to pursue the degree?
Before beginning the degree, while working for the Ministry of Agriculture and Forestry in quarantine, on the border, I would find something suspicious and have to send it to the lab. That is where I took an interest in what I was finding. I began to be able to do some basic identification and save the trip to the lab. It is from that initial interest that I decided to pursue a science degree program.


David Voice and Tommy
Photo by Juli Diamond

What does your job now entail?
My title is Scientist, in the Entomology department of the Plant Health and Environment Laboratory at the Ministry of Agriculture and Forestry.

Primarily I work as a lab coordinator. I do diagnostics and project work on high impact species that would cause harm to the environment in New Zealand if they arrived.

I practice diagnostic entomology, which is the study and identification of insects, and that requires me to spend some time behind a microscope. I also do surveillance of fruit fly trends and eradication procedures. I recognize research opportunities and design experiments.

How do you feel Lincoln University did at preparing you for this career and what courses were most useful to you?
I feel Lincoln prepared me well because in this field you have to learn the basics about taxonomy, and you need to understand where the creature lies in the greater animal kingdom, as well as the relationship between species and how to ensure accuracy in identification.

Therefore, the courses I took in taxonomy, systematics and pest management were most beneficial to what I was doing. The program itself allowed me to customise my studies towards my career, and courses were available that strengthened my knowledge of the field. I feel Lincoln had excellent lecturers and staff.

What is your impression of your time at Lincoln University and the entomology department?
I thought Lincoln was great, I really enjoyed it. I felt a bit awkward at first - being a senior student, but they were great and treated me like a peer. At that time there was a full entomology department and there were a lot of people working on different insect-related research. I felt the work being done was really comprehensive. I also was very motivated because I could see how I could apply what I was learning directly to my job.

What advice do you have for current or prospective students regarding how to make the most of their study at Lincoln University?
I’d like to say that biosecurity is a highly significant field that New Zealand needs to take great heed of, because we still haven’t seen the worst invasive species. I think there are a lot of opportunities in the biosecurity sector, including policy and laboratory work. There is a lot at stake and we need more individuals to come out of university knowing about these issues who can make good policy and protect New Zealand from exotic pests and disease.

Any other comments?
I’d like to close saying that studying entomology gives you a wonderful understanding of how nature operates. There is a lot going on in the environment and there should be a balance, and when that gets disturbed things can go wrong. That is often how pests emerge and by knowing and understanding the system we will be able to prevent that from happening.

David Voice felt very positive about his experience studying entomology at Lincoln University, are you interested in learning more about the program? Contact John Marris, Curator of the Entomology Research Museum for more information.

This article was prepared by postgraduate student Juliane Diamond as part of the ECOL 608 Research Methods in Ecology course.