EcoLincNZ

Category: Soil

  • The next big thing… arbuscular mycorrhizal fungi

    The next big thing… arbuscular mycorrhizal fungi

    Aotearoa’s nature is defined by its iconic species like kauri and pōhutukawa, kiwi and kea, and even insects like wētā. These species are undeniably important, but it’s now time for some credit to be given to a less visible group – arbuscular mycorrhizal fungi (AMF). 

    Little known to most, AMF have been an important part of the Earth’s ecosystems for 450 million years. Around 80% of all plant species live in symbiotic relationships with AMF.

    AMF colonise plant roots and support the host plant by extending fine filaments, called hyphae, into the soil. These tiny hyphae can access water and nutrients that would otherwise be missed by the host plant’s roots. This gives plants a major boost. The extra intake of limited nutrients, like nitrogen and phosphate, enhances the plant’s resistance to environmental stressors – such as disease or climate change.

    Native Forest, Tauranga. You can’t see them, but AMF are in this photo! Photo by Ngaire Ferriss

    But it’s not all one-sided. AMF benefit too, receiving carbohydrates and fatty acids from the plants in return for their work. 

    It’s no secret that native Aotearoa ecosystems are struggling. Anthropogenic challenges, like climate change, deforestation, invasive species, and soil depletion (I could keep going), make it difficult for our native plants, and the fauna which they support, to thrive.

    The same goes for our valuable agricultural systems, which struggle with similar challenges. Luckily, a recent review of AMF in Aotearoa’s ecosystems suggests that these fungi may be able to help us out.  

    Aotearoa is home to 38 identified species of AMF. It is thought that there is functional specialisation across species, meaning that each species can offer different benefits to its host plant. 

    Kānuka forest, Paparoa. Kānuka commonly interacts with AMF. Photo by Ngaire Ferriss

    Studies show that AMF have the ability to improve plant growth. For example, kānuka and mānuka growth was significantly enhanced when AMF was added to the soil. Another study showed an increase in root and shoot growth in the sample apple trees. These benefits can assist with disease resilience, as greater size means greater defence. 

    Crop plants can also benefit from this growth. When New Zealand-made mycorrhizal products were applied to plants like lettuce and plantain it increased the size of the crops. Other plant species saw an improved nutrient uptake, which can assist with carbon storage in soils. Aside from helping plant health, this is a global warming win, locking carbon away and preventing it from accumulating in the atmosphere. And unlike chemical fertilisers, mycorrhizal products don’t contribute to soil depletion. While a great temporary solution, crops relying on fertilisers lack many of the components soil needs to thrive. On the other hand, AMF add organic matter, nutrient availability, and long-term soil health. 

    So far, it’s sounding pretty good. However, AMF isn’t the solution to all our problems yet. Research is expensive, and we currently lack knowledge on AMF species, functions, and relationships with plants. The next steps in advancing AMF research include increasing AMF culture collections, characterising communities at a precise level, and discovering associations with plant species. If this can happen, a whole world of benefits could be unlocked. Native plant diversity and abundance could shoot up with specific applications of AMF – increasing resilience to stress, enhancing growth, improving soil quality, and improving competition with invasive species. Agriculture could also be supported by these fungi, using crops which support diverse AMF communities. By making use of the skills of different AMF species, crop plants could enjoy increased nutrient uptake and resilience, creating more productive and sustainable farms.  

    It seems our secret weapon has been beneath our feet all along. Now that AMF have had their big introduction, perhaps they can help forge a new path toward healthier soils, healthier ecosystems, and a healthier Aotearoa.  

    This article was prepared by Postgraduate Diploma in Applied Science student Ngaire Ferriss as part of the ECOL608 Research Methods in Ecology course.

  • Is nitrogen the only driver of freshwater eutrophication?

    Is nitrogen the only driver of freshwater eutrophication?

    Imagine a typical stream or river running through farmland. It looks clear enough at first glance, but you start to notice something is not right. Algae begins appearing over time. The water quality gradually declines. Something is leaking into the ecosystem and altering the natural environment.

    So the question becomes: what is responsible?

    For a long time, scientists suspected a single culprit. But, in the early 2000s, soil scientist Andrew Sharpley and his colleagues, including Lincoln University researcher Professor Richard McDowell, set out to investigate why water quality problems persisted even when nutrient management practices were in place.

    Their research, published in Plant and Soil (Sharpley et al.,2001), revealed that nutrient loss from farms to freshwater was far more complicated than previously thought.

    Instead of one obvious offender, the evidence pointed towards two main suspects: nitrogen and phosphorus.

    Solving this mystery changed how we manage nutrients within agricultural landscapes.

    Scoping the area over Waitaki River at Ikawai, Canterbury. Photo taken by author. CC-BY-NC

    Suspect #1: Nitrogen- a.k.a ‘the quiet traveler’

    Nitrogen moves easily through soil, making it difficult to trace back to its source.

    Unlike phosphorus, which tends to stick to soil particles, nitrogen is highly mobile. It likes to dissolve in water and travels easily through the soil profile into groundwater systems, ultimately reaching streams and rivers. Because of this MO (Method of Operation/ Modus Operandi), nitrogen losses often occur out of sight below the surface, making them harder to catch and manage.

    For a long time, nutrient management strategies focused heavily on the reduction of nitrogen loss. That made sense. If nitrogen moved easily through soil and into waterways, then controlling it should have solved the problem, right?

    Well it didn’t.

    Even when nitrogen losses were reduced and put under house arrest, freshwater quality issues often remained. This meant something else was involved… nitrogen had an apprentice picking up the slack.

    Suspect #2: Phosphorus- a.k.a ‘the one hiding in plain sight’

    Phosphorus has a different MO to nitrogen. Instead of traveling through groundwater channels, phosphorus often attaches itself to soil and sediment particles and is transported during rainfall and runoff events. Although dissolved phosphorus can also contribute to eutrophication, most phosphorus losses are strongly linked to surface processes, such as erosion and overland flow. It, essentially, disguises its movements during significant events, helping to evade detection.

    Sharpley and colleagues showed that this difference between nutrients matters. Managing nitrogen alone was not enough, because phosphorus followed different pathways through the landscape.

    Even more interestingly, strategies that were designed to reduce nitrogen loss sometimes came with unintended consequences. In some cases, the application of manure that was applied based on the crops nitrogen requirements, had repercussions that caused phosphorus to accumulate in soils, increasing the risk of phosphorus loss during runoff events.

    So the investigation suddenly became more complicated.

    It wasn’t just about catching one suspect anymore.

    An event that our suspect uses to disguise its movements while being attached to soil particles. This example is the Leith River, Otago, in flood. Photo taken by author. CC-BY-NC

    A breakthrough clue: location matters more than we thought

    By this point, researchers realised that nitrogen and phosphorus behave differently, travel through landscapes in different ways, and require different management strategies.

    One of the most important insights from this research was that nutrient loss doesn’t happen evenly across farms. Instead, it tends to occur in specific areas where high nutrient availability overlaps with the active transport pathways, such as runoff.

    These are known as Critical source areas.

    Think of them as the crime scene hotspots.

    Not every paddock contributes equally to nutrient loss. Some areas of the farm are more prone to loss than others, especially where saturated soils, slopes or drainage pathways allow for nutrients to move quickly into waterways.

    This changed the way scientists and researchers approached nutrient management. Instead of trying to control the nutrients everywhere at once, the attention shifted towards identifying the places where interventions would make the biggest difference.

    Following the evidence: the phosphorus index

    Once researchers realised that location played such an important role, they needed a way to identify where losses were most likely to occur. This led to the development of tools like the phosphorus index.

    Rather than simply measuring how much phosphorus was present in the soil, the phosphorus index combines information about soil phosphorus levels with landscape features, such as slope, runoff risk and transport pathways. Together, these factors help identify where phosphorus is most likely to leave the farm and enter waterways.

    Instead of treating entire farms the same way, the phosphorus index helps target management practices to the places that matter most.

    Almost like predicting the potential next target location.

    Example of potential critical source area where nutrient runoff and drainage pathways overlap. Photo CC BY-SA 2.0 by Doug Kerr.

    Plot twist: solving one problem can create another

    One of the most interesting outcomes from this research was the discovery that managing nitrogen and phosphorus separately can sometimes create trade-offs between them.

    Practices that were designed to reduce nitrogen losses can increase phosphorus accumulation in soils simultaneously. At the same time, strategies that reduce phosphorus runoff can increase nitrogen losses through drainage pathways.

    This meant nutrient management couldn’t focus on just one suspect anymore. Both needed to be considered together.

    That shift in thinking helped to reshape how scientists and land managers approach water quality protection today.

    Despite these advantages, the case is far from closed. Excess nitrogen and phosphorus continue to enter waterways in New Zealand and around the world, contributing to algal blooms, reduced water clarity, oxygen depletion and the degradation of freshwater ecosystems. While researches now have better tools to identify and manage nutrient losses, protecting water quality remains an ongoing challenge.

    Why does this case still matter?

    The work by Sharpley and colleagues helped move nutrient management away from simple nutrient solutions towards more integrated approaches that recognise how nitrogen and phosphorus interact across landscapes.

    Instead of asking how many nutrients are present, researchers began asking: Where are they most likely to move to?

    That question led to better tools, better targeting of mitigation strategies and a stronger understanding of how agricultural systems influence freshwater quality.

    By recognising that both nitrogen and phosphorus contribute to eutrophication through different pathways, scientists and land managers are better equipped to reduce excessive algal growth and protect the health of rivers, streams and lakes.

    The mystery of nutrient loss is far from completely solved. But thanks to research, we now know where to look and which suspects deserve the most attention.

    This article was prepared by Master of Science student Emma Meikle as part of the ECOL608 Research Methods in Ecology course.

    • Sharpley, A. N., McDowell, R. W., & Kleinman, P. J. A. (2001). Phosphorus loss from land to water: integrating agricultural and environmental management. Plant and Soil, 237(2), 287–307. https://doi.org/10.1023/a:1013335814593
  • The war beneath your feet: soil decides the fate of plants

    The war beneath your feet: soil decides the fate of plants

    You stride through lush grasslands. The scenery seems perfect. But lurking just below your feet is a battlefield.

    It’s not an obvious one, of course. There are no bombs going off or explosions or yelling; but there are millions of tiny creatures locked in battle for resources and life. And whoever wins determines whether the plant life above it survives.

    This blog post has been inspired by research published in 2015 by scientists of Lincoln University, AgResearch, and their international colleagues. They examined whether soils from different pastures in New Zealand naturally inhibit soil-borne plant pathogens.

    Figure 1. Grass roots penetrating the soil. The majority of activities that affect plants occur below ground level. Source: iStock/Getty Images

    The Invisible Threat

    Many important plant diseases originate underground rather than from the aerial parts of plants, such as leaves. They attack plant roots and stems before visible symptoms appear above ground. By the time one notices any symptoms of disease, the damage may already have been done.

    And here is the scary part: these silent killers can reduce pasture productivity by 40–50%. Can you imagine how devastating it is to lose nearly half of your production to something unseen? Such is the case in pastures where crop rotation and chemical controls cannot always solve the problem.

    Instead of asking the conventional question, scientists started to wonder:

    What if the soil could defend itself?

    Soil Is Not Just Dirt

    It is easy to think of the soil as lifeless material, but this is far from the truth. Soil is one of the most biologically diverse ecosystems on Earth. A complete microbiota lives within it: bacteria, fungi, and other microorganisms interact continuously. While some assist plants in absorbing nutrients, others … kill them.

    Some soils inhibit diseases. Such soils are referred to as disease-suppressive soils, and their action falls into two categories:

    General suppression: the microbiota competes with the pathogen,
    Specific suppression: some microbiota attack the pathogen itself.

    Soils with high plant diversity likely contain more diverse microbiotas, which suggests a high disease-suppression capacity.

    But how can one measure such a phenomenon?

    A Clever Way to Test Soil

    The researchers developed an interesting experiment to test the soil under examination. Rather than using conventional grass or legumes that can be found on pastures, they opted for something completely out of the ordinary: kale.

    And why kale? This plant is not usually used on pastures. If disease does not occur, then it shows that the soil is pathogen-resistant in general.

    Furthermore, they exposed the plants to a well-known pathogenic fungus named Rhizoctonia solani. And this one leads to a specific disease called damping-off. Plants affected by the disease exhibit dark lesions near the base of the stem which cause plants to fall, like broken wires.

    So, basically, the process works as follows:
    Introduce the same plant into different soils;
    Infect the plant with the same pathogen;
    Observe the results.

    Figure 2. Seedling damping off showing dark spots on stem bases. Seedling damping off may result in death of the seedling before establishment. Image credit: AA Seif and AM Varela, icipe. Source: CABI PlantwisePlus Knowledge Bank.

    All Soils Are Not Equal

    The experiment was conducted using four New Zealand pasture soils, including Lincoln, Eyrewell, Rotorua, and Kurow soils.

    Same plant. Same pathogen. Entirely different results.

    Some soils promoted rapid spread of pathogens; others reduced their effect considerably. There were significant differences between disease levels in the various soils.

    • Final disease levels were highest in Rotorua soil.
    • Disease progression rate was highest in Kurow soil.
    • Lincoln soil displayed maximum resistance, with minimal disease levels in the control.

    Same experiment. Different soil. Entirely different results.

    And here comes the moment when it all becomes evident:

    Soil is not just a neutral element. It actively influences the experiment.

    If a soil keeps plants healthy, it’s suppressive. If plants collapse… not so much.

    Figure 3. Sampling the soil is essential for research purposes on the properties and disease suppression abilities of soils. Image credit: William, Adobe Stock. Source: Farmers Weekly.

    The Twist: Some Soils Had Been Infected Already

    Without even having introduced the pathogen, some soils exhibited symptoms of infection. For instance, in Kurow soils, damping-off disease symptoms appeared in the control group as well. This indicated that the pathogen was already present but dormant until the required environmental conditions prevailed.

    It could be termed an underlying threat embedded in the soil. Furthermore, pathogens, such as Rhizoctonia solani, can survive between successive cropping seasons, affecting both pastures and future agricultural crop growth.

    It’s Not Only “How Many” but Also “How Quickly”

    Besides assessing how many of the plants became diseased, the authors also took into account the dynamics of disease development. Why does this matter?

    This is important because a slowly developing disease will allow the plants to develop properly before being affected. The faster moving disease will kill them much earlier.

    Two metrics were used to assess this:
    Disease Incidence (DI) – number of infected plants at the end;
    Area Under Disease Progress Curve (AUDPC) – a measure of disease development over time.
    Imagine that:
    DI is the final result
    AUDPC is the whole game
    And often, their narratives may be very different.

    Why It All Matters

    It isn’t just scientific research for research’s sake. With knowledge of how soils resist disease, we could:

    • Improve our soil management techniques,
    • Cut down on chemical use,
    • Increase productivity from our crops and pastures,
    • Create a more sustainable agricultural process.

    Rather than battling pathogens directly, we could fortify our soil against disease.

    That’s where it gets revolutionary.

    The Bigger Picture

    Agriculture of the future may rely less on adding things to soil…
    And more on what is already thriving beneath its surface.

    When you look at a flourishing farm, remember this:
    It is not only the plants that prosper. There is an entire ecosystem underground, sustaining all life. And in this unseen world, each microbe counts in the battle beneath our feet.

    This blog was prepared by Vikram Shankar Malagi, a Master of Bioprotection student at Lincoln University, as part of an assignment for ECOL608 Research Methods in Ecology.

    References:

    Dignam, B. E. A., O’Callaghan, M., Condron, L. M., Raaijmakers, J. M., Kowalchuk, G. A., & Wakelin, S. A. (2015). A bioassay to compare the disease suppressive capacity of pasture soils. New Zealand Plant Protection, 68, 151–159.

    http://www.nzpps.org/nzpp_abstract.php?paper=681510



  • The pines are invading! Planting non-native species increases re-invasion

    The pines are invading! Planting non-native species increases re-invasion

    Soil is life

    I’m not sure if you’re aware, as I was not aware of this before coming to Lincoln University, but soil is very much alive. There are millions of organisms in a single handful of soil. These critters perform the majority of the ecosystem services provided by soils.

    In New Zealand, these organisms range from burrowing animals, to soil-dwelling invertebrates, to fungi, to microscopic bacteria and much more. So next time you walk on soil, think about how much life is beneath your feet.

    For plants, a major component of successful growth and survivability is the soil microbiota, such as bacteria, fungi, viruses, nematodes (tiny worms), and many more. I have much love for fungi in the soil microbiota, especially mycorrhizal fungi that are essential for plant growth.

    Mycorrhizal fungi form mutualistic relationships (beneficial for both organisms) with plant roots. The fungi extend their network to increase the nutrient intake in exchange for carbohydrates that the fungi cannot produce itself.

    There are two major types of mycorrhizal fungi, ectomycorrhizal fungi, which infect the outside of plant roots, and arbuscular mycorrhizal fungi (AMF or endomycorrhizal), which infect the inside of plant roots.

    I did a project on ectomycorrhizal fungi abundance on red beech tree roots for SCIE393 where I took this photo of an ectomycorrhizal fungal fruiting body (mushroom) under the microscope (which I thought was very cool). This is really where my love for mycorrhizal fungi started to blossom.

    Ectomycorrhizal fruiting body under the microscope – Photo by Lucas Watkin (CC-BY-NC)

    Exotic plants are strong invaders

    That’s enough about me for now, time to talk about invasions from non-native plants. As I’m sure everyone who lives in New Zealand is aware, we live in an invaded country, full of exotic predators, pests, and weeds.

    While everyone tends to think of the worst invaders are pests like possums and mustelids, the worst invaders are actually the weeds. Approximately half of all the vascular plants in the wild in New Zealand are non-native. There are around 25,000 exotic plant species that have been introduced to New Zealand, with around 2,700 of these becoming wild. Compared to around 2,500 native plants, this is an insane numbers of exotic plants and so to conserve our native species, we must do something about all of these exotic species.

    From grassland to pineland: The rapid invasion of black pine into well grazed high country pasture – Photo by Jon Sullivan (CC BY-NC 2.0)

    One of the worst exotic plant species are wilding pines, such as lodgepole pine and radiata pine. Lodgepole pine was introduced into New Zealand in 1880 to combat erosion. Burning of forests, overgrazing, and introduced browsers, such as deer, goats and rabbits, were clearing the hillsides of our native plants, leading to more slips. The New Zealand government decided to plant exotic plants, specifically Douglas-fir and lodgepole pine to cover the hillsides and reduce erosion.

    These pines did stop the erosion, however, what was not anticipated was the enormous dispersal ability of these wilding pines. Seeds of wilding pines can survive for a decade in their cones, grow roughly anywhere, and can travel kilometers from their parent. There is now roughly 800,000 hectares of wilding exotics in the South Island alone, two thirds of which is lodgepole pine!

    Wilding pines of Flock Hill Station: The very many wilding pines coming out from the experimental forestry plots in adjacent Craigieburn Forest Park – Photo by Jon Sullivan (CC BY-NC 2.0)

    Be careful what you plant!

    This paper headed by Joanna Green has contributions from my lovely thesis supervisor Lauren Waller. In it they describe the effects of planting non-native plants on the soil microbiota, and how that can impact what grows there afterwards. They were specifically looking at how well lodgepole pines grow in soils that have been used and conditioned by exotic plant species.

    Joanna and Lauren started by using soils that had already been conditioned by 19 native and 20 exotic plant species from another two experiments by Warwick Allen and Lauren Waller. The soil microbiota, the nutrients in the soil, and other factors, like the pH of the soil, had been changed to best suit the plant that had been grown in that soil.

    An example of part of the soil microbiota that was conditioned were the ectomycorrhizal fungi. These fungi are required for successful growth by some of our native species, such as our beech, mānuka, and kānuka species. However, exotic species use different species of ectomycorrhizal fungi than our native species. Therefore, when exotic species are grown in soil they will grow well with their species of ectomycorrhiza.

    Basically, think of it like this. If you owned a garden and really liked roses, you would grow a lot of roses. You might grow some other plants but the focus of the garden would be on roses. Now, if someone else came in and took over the garden for themselves, they might not like roses as much but might really like petunias. They will then plant petunias in place of where the roses used to be, altering the state of that garden.

    In terms of ectomycorrhiza, they require associations to survive, so the native ectomycorrhiza species that were in the soil will die after their native plant partners are gone. Exotic ectomycorrhiza species associated with exotic plant species will then survive. Due to this, it will become a lot more difficult for our native species to grow back in that soil due to a lack of ectomycorrhiza that they can grow with. Conversely, it will be a lot easier for exotic plant species to grow in partnership with a large number of exotic ectomycorrhiza.

    Anyway, back to the paper. The researchers found that lodgepole pine grew better in soils that had been conditioned by exotic species, such as black alder, cocks-foot, spear thistle, gorse, and many more. And this was regardless of whether pines had been planted there or not! Lodgepole pine will have a much easier time establishing and invading into areas that have previously had exotic species growing there.

    Lodgepole pine tree near Lake Benmore – Photo by abcdefgewing (CC-BY-NC)

    So why does this matter?

    To conserve our native plants, sometimes we must plant them in areas that have previously grown exotic species. Joanna and Lauren’s research shows that the soil will be conditioned to favour growth of exotic species, and so growing native plants will be more difficult. It will also be a lot easier for exotic species, such as lodgepole pine, to re-invade and take over the conservation site. Therefore, conservation managers must be aware of this soil legacy and decisions must be made in order to manage this re-invasion potential.

    So, next time you want to plant an exotic plant, think about the soil, and whether you would rather plant a native instead.

    This article was prepared by postgraduate student Lucas Watkin, Master of Science in Conservation and Ecology, for an assignment in ECOL608 Research Methods in Ecology.

    Green, J. L., Waller, L. P., Allen, W. J., Orwin, K. H., Pelser, P. B., Smaill, S., & Dickie, I. A. (2025). Plant-soil feedback from non-native communities increases pine invasion and re-invasion potential. Plant Soil, 514(2), 2461-2474. https://doi.org/10.1007/s11104-025-07528-x

    Featured image: Did somebody order pines? The rapid invasion of black pine into well grazed high country pasture – Photo by Jon Sullivan (CC BY-NC 2.0)

  • Polka dots, patches and pinstripes? Productive pasture patterns

    Polka dots, patches and pinstripes? Productive pasture patterns

    Do I need to apologise for the overly alliterative title? The excessive use of P’s aside, this title is still ridiculous, who has seen a polka dot pasture? Or a pinstripey paddock? They sound like a figment of Dr. Seuss’ imagination!

    But they’re not, it’s science – an ingenious recipe, mixing landscape design, with a pinch of ecology, and a tablespoon of agriculture. Let’s get cooking!

    When did we (and by we I mean the human race/ Homo sapiens/ mankind/ womankind/ humanity/ Earthlings), when did we decide that livestock grazing pastures were to be squares of fenced grass? It was probably somewhere around 12,000 years ago when we stopped being nomadic and started agricultural farming.

    Fenced grass pastures work, they have been working for thousands of years. But times they are a’changing (insert a “back in my day…” quote here). The human population (no more we’s, it’s getting serious now) has swelled into the billions (8,286,120,266 at the time of writing), requiring massive agricultural landscape expansion to sustain us.

    There is no better example of this than where I live; the Canterbury Plains of Aotearoa New Zealand. Less than 0.5% of Canterbury Plains’ native bushland has survived the ever-expanding agricultural and residential landscapes. This is where we run into our big pinch of ecology – if we were to put the native plants and animals back, where would they go?

    The answer – into polka dots, patches and pinstripes.

    I’ll explain what the patterns are about, as I know you’ve been waiting patiently. They are landscape design patterns of native woody plants within an agricultural livestock pastural setting. They are the answer – cohabitation of native habitats and productive farming, all within one landscape.

    Lincoln University‘s multi-disciplinary researchers, James Eggers, Shannon Davis, Crile Doscher and Pablo Gregorini, are the large brains behind this pioneering conceptual design. In their study, they list ideal native woody plant species that can be used to both enhance livestock welfare and restore bush habitats for native birds.

    Now we’re cooking with renewable energy, and we’re baking three cakes in one pan – through increasing foraging opportunities for livestock, providing shade and shelter for these livestock, and establishing native bird sanctuaries. Wow!

    Picture this – you’re a farmer and this is your Canterbury Plains farm. Nice, right! You have multiple grass paddocks where you graze sheep and cattle. In reality, this is Lincoln University’s Ashley Dene Farm which was used as a case study for this research, but in this virtual Blog, it’s yours.

    Figure 1: Aerial view of Ashley Dene Farm Image © 2023 by J. Eggers et. al. Licensee MDPI, Basel, Switzerland. CC-BY 4.0

    Let’s say you want to increase foraging opportunities for your livestock. You know that foraging woody vegetation has long been recognised as beneficial. Woody vegetation tolerates poor soils and weather conditions. It provides a range of nutrients and medicinal properties for optimal livestock health. Also, a diversity of forage enhances livestock consumption and can lengthen the grazing season. Finally, foraging allows livestock to exhibit natural browsing behaviour, thereby boosting welfare.

    Lucky for you, thanks to this research, we have a list of optimal foraging native shrubs and small trees (shorter plants for livestock access) selected for palatability, tolerance for browsing and growth rate. Now for the fun part – how to arrange these plants. We have three patterns…

    Polka dots (or patches): vary in size and are placed within pastures. The central area is fenced to prevent overgrazing and to accommodate natural seedling regeneration.

    Figure 2: Polkadots. Image © 2023 by J. Eggers et. al. Licensee MDPI, Basel, Switzerland. CC-BY 4.0

    Spreading: balances access to forage, preventing over browsing through the use of a central fenced off strip. It preserves maximal grazing pasture by running along pre-existing fence lines. Livestock can be moved between paddocks/sides of the spreading forage to allow for regeneration on one side whilst the other is browsed.

    Figure 3: Spreading. Image © 2023 by J. Eggers et. al. Licensee MDPI, Basel, Switzerland. CC-BY 4.0

    Pinstripes (or just stripes): maximises foraging opportunities and is compatible with farming that uses large machinery. The stripes are within a single paddock, placed 40 m apart for optimal browsing, and temporary fencing is used to designate/restrict feeding areas.

    Figure 4: Stripes. Image © 2023 by J. Eggers et. al. Licensee MDPI, Basel, Switzerland. CC-BY 4.0

    Back to your hypothetical farm, you now have an amazing amount of native forage for your livestock. However, with your farm being on the Canterbury Plains, it is constantly hounded by northeasterly, hot northwesterly, and cold southwesterly winds. Your animals need shelter. Shade and shelter for livestock reduces heat/cold stress, excess moisture loss, improves animal wellbeing, increases feed intake and lamb survival rate.

    Here is a native solution with multiple benefits, no more English hedgerows that provide little to no food for wildlife. Native trees and dense shrubs are selected for their height, shade, canopy, and provision of shelter. Unlike the foraging designs, these shelter patterns are fully fenced off to allow for optimal plant growth without the pressure of grazing.

    Straight shelter: a pretty straight-forward design (see what I did there) providing shelter in areas of limited space.

    Figure 5: Straight shelter. Image © 2023 by J. Eggers et. al. Licensee MDPI, Basel, Switzerland. CC-BY 4.0

    Meandering shelter: similar to the straight design, however, with a greater width to act as a wildlife corridor and habitat.

    Figure 6: Meandering shelter. Image © 2023 by J. Eggers et. al. Licensee MDPI, Basel, Switzerland. CC-BY 4.0

    In-paddock shade trees: taller trees are placed through paddocks, in groups or individually, to provide shade. There is no underplanting to allow for a cooling breeze.

    Figure 7: In-paddock shade trees. Image © 2023 by J. Eggers et. al. Licensee MDPI, Basel, Switzerland. CC-BY 4.0

    Ah, that’s nice. Now your sheep and cattle are well fed and comfortable. The productive capacity of your farm is in order. But, you also care deeply about native wildlife and want to do everything you can to protect them (but not with a loss of productivity for your farm). Is this possible? Well, let’s see…

    James and his team designed native bird bush habitats around a wetland corridor, an area of pre-existing mature trees, and a densely planted area. Densely planting native bushland are better at dealing with edge effects, reducing the distance that light and sound pollution can travel into the patch, and increasing bushland’s suitability for sensitive birds (like kererū). The mature trees act as nurse species for the native seedlings and the wetlands will breed waterborne insects – an additional snack for many bird species.

    Whilst the forage and shelter plantings were determined by the needs and landscape of the farm, placement of bush habitats required consideration of the wider landscape. Preference was given to the native bird habitat locations as they had specific requirements. Native bird habitats must connect to a wider established ecological network for birds to be able to travel to the site (within 5-25km distance dependent on the bird species). Amazingly, native bird abundance can almost quadruple with the addition of restored bushland to agricultural landscapes. This research identified ultimate native plants that provide bird food sources and nesting sites.

    Figure 8: A comparison of your farm with and without native woody vegetation additions in a combination of design patterns for livestock forage, shade and shelter and native bird bush habitats. Image © 2023 by J. Eggers et. al. Licensee MDPI, Basel, Switzerland. CC-BY 4.0

    So now you have an ideal farm! It balances livestock productivity and native bird habitats through adding an abundance and variety of native plants (an increase of 30% woody vegetation in the case study farm). And yes, there may be a reduction in the grazing land area, but, this is offset by increased forage vegetation, combined with fallen organic matter improving soil health and productivity. The addition of native bird habitats will likely have little impact on farming operations.

    Forage patterns can be integrated into shelter patterns to maximise land use for grazing. Likewise, forage plantings can be placed next to bush habitats to create multifunctional areas. Shelter and forage plantings can complement the bush habitats, by acting as wildlife corridors, edge habitats, and increase plant species diversity. Your imagination is the limit when it comes to combining and implementing the design patterns, however, site specifications, soil types, climate conditions, livestock density, paddock use, and wildlife reserve proximity need to be considered… so maybe your imagination isn’t the limit, as every farming landscape has different specifications.

    We are achieving an agricultural ecological landscape in one location, with broader ecosystem benefits. Restoring and integrating native habitats into farming practice can encourage others to follow, and together we can support the revival of native birds to our currently fragmented landscape. This research kneads together two strong cultural identities of Aotearoa New Zealand – its rich farming history and outstanding natural biodiversity – fortifying and concentrating both.

    As these Patches, Polka dots, and Pinstripes do sound like a Dr. Seuss story, it is only appropriate to end with,

    “Unless someone like you cares a whole awful lot,

    nothing is going to get better.

    It’s not.” – Dr. Seuss’ The Lorax

    So thanks to all of you reading this, farmers or not, I know that you care a whole awful lot.

    This article was prepared by Klara Royster, Master of International Nature Conservation student, for an assignment in ECOL608 Research Methods in Ecology.

    Reference Research Journal Article: Eggers, J., Davis, S., Doscher, C., Gregorini, P. (2023). Enhancing Multifunctionality in Agricultural Landscapes with Native Woody Vegetation. Sustainability Journal, 15, 11295.

  • The Magical World of Grass and Clover

    The Magical World of Grass and Clover

    *Disclaimer: This article contains Harry Potter references

    After four years of living and studying together, you would think you know someone pretty well. Alas, last week it turned out one of my flat mates had never seen (or read) Harry Potter… shocked, heartbroken, and outraged – the only way to solve this flat feud was to start from the beginning and watch Harry Potter and the Philosopher’s Stone.

    The next day, it was back to study. However, I couldn’t get the wizarding world out of my mind, especially knowing that the second movie, the Chamber of Secrets, was scheduled for that night. It got me thinking. Every hero has a sidekick. Batman and Robin, Frodo and Sam, Harry and Ron. But what if these iconic heroes don’t only exist in the worlds of Gotham City, Middle-earth, or Hogwarts. What if the heroes on this earth have sidekicks too?

    Legumes (like clovers) are heroes. Destined for greatness and capable of incredible things, they can capture nitrogen (N) from the atmosphere and convert it into ammonia, a biological form of nitrogen that fuels the ecosystem. Farmers often incorporate clovers into their pastures to provide nitrogen into the system. Because of their magic-like nitrogen capturing abilities, clovers boost the growth of neighbouring grasses and create an increase in food quality and quantity for grazing animals.

    White Clover (Trifolium repens). CC BY 2.0. Harry Rose

    It is generally understood that this is a one-way relationship, meaning clovers are humble heroes that provide N to the grasses and plants surrounding them. However, through my muggle research, I came across a recent study titled “Grasses procure key soil nutrients for clovers” by PhD student Zhang Wei.

    Could it be? A sidekick to our green three-leaf (sometimes four if you’re lucky) hero?

    Wei and his team questioned whether we properly understand the relationship between clovers and grasses. For the purpose of this article, let’s think of clovers and grasses as characters to understand better their relationship and how they work together.

    Perennial Ryegrass (Lolium perenne). CC BY-SA 4.0. Michel Langeveld

    Different plant species have various magic-like abilities to acquire nutrients. Grasses, for example, are potion makers and can release chemical substances into the soil to make elements such as iron (Fe), zinc (Zn), copper (Cu), and manganese(Mn) more available in the soil. Other plants call on the Room of Requirement and collaborate with fungi to increase access to nutrients through the fungal networks. Like how the Room of Requirement appears for those who need it most, fungi create symbiotic relationships with plants, enabling more nutrients to ‘appear’ and become more accessible in the soil. And clovers, as you now know, use their spellwork to fix atmospheric nitrogen (N).

    However, just like the spell “Wing-gar-dium Levi-o-sa” requires a certain pronunciation, N fixation requires a certain nutrient – phosphorus. Phosphorus is a nutrient constantly in high demand for clovers due to N fixation being such a taxing process.

    Zhang Wei and his research team carried out experiments to better understand how grasses influence the nutrient availability for clovers. Clovers and grasses were grown separately in individual pots, much like Harry living alone in the cupboard under the stairs. They were also grown together in shared pots, similar to Harry and Ron bunking together at Hogwarts. Measurements were then taken from the soil and leaves in all the pots to understand how the clovers and grasses influence each other’s growth.

    The researchers found that grasses promoted the growth of clovers when grown together. This was evident when higher amounts of nutrients such as nitrogen (N), phosphorus (P), potassium (K), and sulphur (S) were found in clover leaves growing with grasses compared to clovers that grew alone. Grasses give clovers a boost in accessing essential nutrients, much like how Ron supports Harry, offering the strength and loyalty he needs to face He-Who-Must-Not-Be-Named.

    Mixed sward of White Clover (Trifolium repens) and pasture grasses growing together. Nicole Parnell. 2025.

    Additionally, more biomass was achieved when both clovers and grasses were grown together compared to when they were grown apart. How would Harry have gotten through his years at Hogwarts without his friends by his side? They achieve more when they work together. By sharing their resources, the plants could increase their biomass, which boosts livestock feed while lowering fertiliser demand.

    The muggle authors acknowledge that more research is needed to fully understand the complexities of how nutrients move through the soil in plant communities like this, especially under field conditions. In 2023, Zhang Wei and his supervisors took the study into the field and, once again, saw enhanced legume growth when grown alongside a diverse range of pasture grass species. Think of Harry’s resilience and leadership, Ron’s loyalty and humour, and Hermione’s intelligence and discipline, all of which work together to create a strong, unbeatable partnership. Similarly, there is an enhancement of nutrient uptake in diverse pastures with legumes (including native legumes) and grasses. This suggests a possible reduction in fertiliser requirements in pastures with increased plant diversity.

    A study that referenced Zhang Wei’s work similarly found that plant mixtures with various legume and grass species reduced intraspecific competition, a term that explains competition between individuals of the same species (think Gryffindor vs Slytherin). This means that the growth and productivity of both legumes and grasses were further enhanced when grown together.

    Zhang Wei’s PhD study provided further insights into the flow of nutrients within plant communities, demonstrating that grasses also play a vital role in nutrient availability and enhancement. This study builds on the argument that pasture diversity can reduce reliance on artificial fertilisers and promote sustainable farming methods. These methods can increase the ecosystem’s stability, making it more resilient to disturbances such as droughts and/or floods. Like any partnership, growing together makes them stronger.

    That’s where the magic happens.

    This article was prepared by Master of Science student Nicole Parnell as part of the ECOL608 Research Methods in Ecology course.

  • Enemies with benefits

    Enemies with benefits

    The idea of ‘friends with benefits’ is reasonably widespread and understood. Having good interactions with others will often lead to even more productive outcomes. But what about ‘enemies with benefits’? Are there times where your enemy can give you some positive benefits?

    Invasive species cause ecological harm worldwide, threatening biodiversity, disrupting nutrient cycling and displacing native species. Pacific islands, with their characteristically high rates of endemism, experience out-sized effects from plant invasions (Bellard et al. 2014). In biodiversity hotspots, such as New Zealand, exotic invasive plant species now outnumber native species in area and in number.

    But, how do they do it?

    New Zealand habitats are prone to invasion by exotic plant species. Why is this?

    A study by Lauren Waller and other Lincoln University and University of Canterbury colleagues, published in Journal of Ecology attempts to find some answers. Lauren shows that exotic plants may gain their competitive edge by accumulating enemies in the soil and sharing them with neighbouring native plants, a phenomenon that plant ecologists call pathogen spillover.

    Lauren set up a large mesocosm (self-contained area) experiment. These were areas where new species could be added to a known group of native species in a very manageable process. The health and growth of all plants could be measured and microorganisms both present at the start and brought in on the introduced plants could be identified.

    Lauren expected exotic plants to experience improved growth due to escape from pathogens (leaving the burden of enemies behind when they come to NZ). This assumption comes in large part from two well-known hypotheses, the Enemy Release Hypothesis and the Evolution of Increased Competitive Ability (EICA) Hypothesis. Enemy Release states that exotic plants can gain incredible success when they move to a new location lacking the enemy pressure they experienced in their home range, particularly co-evolved specialist enemies. EICA goes a step further to suggest that if exotic plants can escape enemy pressure in their new range, those plants will have more resources to allocate to growth over defence.

    Somewhat supporting Enemy Release, exotic plants did not appear to suffer much from specialist fungal pathogens. However, exotic plants did associate with generalist pathogens. Also, in support of Enemy Release, exotic plants did not appear to allocate resources to defence. Instead, exotic plants appeared to tolerate generalist pathogen pressure without reducing their growth.

    Native Poa grown in a native versus exotic dominated plot.

    Lauren did not expect to see big impacts by exotic plants on native plants, and boy, did they! Native plants just wasted away when grown with exotic plants. It was very sad to watch. This photo shows an example of a native bunch-grass, grown with all native neighbours (left) or in communities dominated by exotic plants (right).

    What explained the out-sized effect of exotic plants on native plant growth? Our network analysis showed that exotics not only accumulated and tolerated generalist pathogens, but they shared their pathogens with native plants. Native plants did not appear to have the same tolerance for this enemy pressure like the exotic plants did. 

    We started by asking ‘are there times where your enemy can give you some positive benefits?’. It turns out that yes there are times when your enemies can help you a lot. In this case if species cause you problems it will be OK for you if they cause competing species even more problems! With invasive species, your microbial enemies can do you a good turn but taking out the opposition.

    Now that’s a real enemy with benefits!

    Lauren Waller and Adrian Paterson wrote this together (and not as enemies!). They are lecturers in the Department of Pest-management and Conservation.

    Bellard, C., Leclerc, C., Leroy, B., Bakkenes, M., Veloz, S., Thuiller, W., & Courchamp, F. (2014). Vulnerability of biodiversity hotspots to global change. Global Ecology and Biogeography, 23(12), 1376-1386

  • Microbes matter in breaking down nitrogen in dairy pastures

    Our eyes are captivated by the breathtaking diversity of the living world, where billions of plants and animals enchant us with their variety and richness, thriving above ground or in water. But we often overlook the organisms beneath our feet, in the hidden world of soil, where an equally mesmerizing realm teems with life.

    E. R. Ingham: “Just one spoonful of soil can be home to millions of microbes“- the astonishing dynamic of these tiny, unseen organisms would blow our minds, if we only knew their story.

    I am fascinated by the biodiversity of the massive underground community. Countless small living things, such as microbes, insects, and earthworms, are tirelessly at work, busily breaking down organic matter and waste like leaf litter, faeces, and other dead organisms.

    Soil sample under the microscope, Image credit: © William Edge
    from Dreamstime.com CC BY-NC 2.0

    These organisms play fundamental roles in decomposition and also contribute to unlocking essential nutrients, like nitrogen and phosphorus, making these nutrients more available to plants. However, some microbial species can degrade useful substances, primarily affecting the cropping system and leading to lower crop yields in agriculture.

    In New Zealand, our grazing pastures face a significant challenge of soil microbes depleting essential nitrogen (N) in the soil. The NZ dairy industry has a substantial economic impact. A report by Sense Partners highlights that DairyNZ accounted for a quarter of New Zealand’s total export earnings (26 million) in 2023, making it a crucial contributor to national prosperity. For dairy farmers, “grass is green gold” because high-quality pasture is the key to their success, supporting healthy and productive livestock.

    Nitrogen boosts pasture supply, especially when N fertilizer is applied in mid to late spring. In most regions, this application results in an optimal and reliable grass response of around 10 to 15 kg DM/kg N. Why the need to apply synthetic fertiliser when nitrogen is abundant in the atmosphere, which contains 78% nitrogen. The catch is that atmospheric nitrogen is not directly available to most plants (except for legumes) due to its highly stable form (N2).

    Given the necessity of nitrogen fertilisers in grazing pasture systems, a go-to choice is urea. It’s most cost-effective and the most widely applied nitrogen fertiliser in NZ dairy pastures. The scale of its usage is staggering, with over 400,000 tonnes of urea being used annually in dairy farm systems since 2013.

    Two Cows by Martin Gommel | Flickr | CC BY-NC 2.0

    There is a downside. Ammonia-oxidizing soil microbes release an enzyme called urease that can break down over 80-90% of urea fertiliser when soil moisture is high. This leads to significant economic losses for farmers and contributes to environmental pollution through nitrate leaching.

    Note: Urea is the substance of solid nitrogen fertilizer, while urease is an enzyme found in plant tissues, fungi, bacteria, and some invertebrates, but not in animals.

    Dr. Hossein Alizadeh, a senior researcher in the Department of Agricultural Sciences at Lincoln University, leads a team focused on addressing the problem of nitrogen loss in soil. They have identified key culprits of rapid nitrogen loss in the soil – urease-producing microbes.

    By understanding these microbes better, the team can develop solutions to enhance the uptake of nitrogen nutrients by pastures and reduce greenhouse gas emissions. This is crucial because nitrogen from livestock urine and agricultural fertilisers converts to nitrous oxide (N2O), contributing to about one-sixth of New Zealand’s CO2 equivalent greenhouse gas emissions.

    To detect the nationwide urea degradation levels in dairy farm pastures, Dr. Alizadeh and his research team collected soil samples from various regions, including Auckland, Canterbury, Manawatu, Marlborough, Nelson, Otago, Taranaki, Waikato, Wairarapa, and the West Coast. The sampled pastures primarily consisted of ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.). Some grazing lands were relatively young, only nine months old, while others had 60 years of usage.

    To determine whether urease-producing microbes are present in different soil samples, researchers measured ammonium production. Urease breaks down urea and nitrogen in the soil converts to ammonia gas (NH3) and nitrate (NO3-) leaching. In the lab, if the urease producer actively breaks down urea and releases ammonia, the Petri dish with cultured microbes will show a pink colour (see Figure below). Additionally, to identify microbial bacteria and fungi, they applied the PCR (polymerase chain reaction) technique, morphological identification methods.

    Urease detection medium for isolation of soil urease producing microorganisms (left) and a purified urease (right). Own work CC BY-NC 2.0

    Hossein found some novel microbial species, such as Pochonia bulbillosa, Mariannaea elegans, and Gliomastixsp., which were reported for the first time for their urease production. The study also revealed variations in urease activity among the isolates and a diverse microbial community composition across different locations. For instance, in Nelson, bacteria were the dominant urease producers in the soil, while in Oxford, it was fungi, marking a significant discovery in soil microbiology.

    The groundbreaking research by Dr. Hossein and his team on identifying urease-producing microbes not only provides fundamental knowledge but also opens up possibilities for practical applications. The findings suggest the potential of manipulating these microbial populations in soil to reduce urease activity, a concept that is being further explored in the N-Bio Boost program led by Professor John Hampton of Seed Technology at Lincoln University. This project, funded by the New Zealand government and the fertilizer co-op Ravensdown, aims to harness a naturally occurring fungal species in the soil to enhance the nitrogen efficiency of plants, promising both environmental and economic benefits for New Zealand.

    So next time you are walking on pasture, pause and appreciate the busy world that is found under your feet!

    This article was prepared by Master of Pest Management postgraduate student Danyu Li as part of the ECOL608 Research Methods in Ecology course.

    Alizadeh, H., Kandula, D. R. W., Hampton, J. G., Stewart, A., Leung, D. W. M., Edwards, Y., & Smith, C. (2017). Urease producing microorganisms under dairy pasture management in soils across New Zealand. Geoderma Regional, 11, 78–85. https://doi.org/10.1016/j.geodrs.2017.10.003

  • Dirty little secrets or tiny heroes of the soil world?

    Dirt was one of my first friends. My earliest days were spent collecting worms from the backyard and trying to convince my parents I hadn’t done any dirt taste testing that day (I probably had, but for purely scientific reasons). I was fascinated by what seemed like an entirely different world in the soil of my parent’s garden. I could find all kinds of goodies from insects to plant roots.

    At university I was introduced to the truly magical world in soil: microbes. Although not visible to the naked eye, the tiny worlds inhabited by fungi, bacteria, viruses, and other unbelievably small things, should not be overlooked. These tiny worlds are called the microbial community and they have important roles in New Zealand forests.

    Photo of soil microbes under a microscope. Photo by Pacific Northwest National Laboratory (CC-BY-NC-SA 2.0)

    A good place to start thinking about microbial communities is our own bodies. Most people have heard of their gut microbiome. The microbes in our digestive system are important for our health from immune function to digestion (especially for dirt tasters). However, some microbes, such as the COVID-19 virus, can make us sick. Soil microbes in forests are not so different.

    Forests are dependent on microbes that cycle nutrients, decompose waster, and aid plants in nutrient uptake. Like humans and the common cold, some soil microbes hurt their associated plants. An example of this is kauri dieback disease, a disease spread by a spore in the soil that attacks tree roots and trunks. This disease hinders the tree’s ability to uptake and transport nutrients, essentially starving and killing the tree. Kauri dieback is incurable and fatal for kauri.

    Tāne Mahuta, the largest surviving kauri. Photo by Jodie Wiltse (Author)

    Kauri dieback is named after the tree it infects, New Zealand’s mighty kauri tree. The Department of Conservation explains that kauri can grow up to 16 m in circumference and live over 2000 years. The legendary status of kauri is clear in the language used to describe them. The largest surviving kauri is called Tāne Mahuta, which means ‘lord of the forest’. If you were to visit Tāne Mahuta today, you would find boot cleaning stations, warning signs, and only be able to view the great tree from a platform. Moreso, entire trails have been shutdown to stop people from spreading soil around kauri. Why?

    A soil microbe, Phytophthora agathidicida, travels under the name of kauri dieback. This microbe cannot be seen with the naked eye but has the power to kill tremendously large kauri trees. In humans, the heroic microbes of our immune system save us when nasty microbes make us sick. Are there unseen heroes hiding in the soil that can help kauri?

    During a PhD project at Lincoln University, Dr. Alexa Byers studied soil microbial communities under kauri to find out. The goal was to identify microbes that suppress kauri dieback and can aid in kauri conservation.

    The first step was to understand how microbial communities under kauri react to kauri dieback disease. Alexa infected kauri seedlings with kauri dieback and looked for changes in the soil microbial community. When humans are attacked by illness causing microbes, our immune system amps up to protect us. When soils were infected, Alexa found bacteria that were involved in disease suppression. This was a promising result suggesting that heroic soil microbes could build up their numbers to fight off kauri dieback.

    Kauri tree bleeding resin, a common symptom of kauri dieback disease. Photo by Onco p53 (CC BY-SA 4.0).

    Next, Alexa looked into how specific strains of bacteria from kauri soil impacted the development of kauri dieback. She identified Paraburkholderia and Penicillium microbes that inhibited the growth of kauri dieback in soils. Paraburkholderia are known to enhance plant growth and fix nitrogen. Penicillium are fungi that can kill or stop growth of other bacteria. We officially have some heroic contenders!

    The battles between heroic microbes and kauri dieback in the soil could determine the fate of the kauri above them. Hopefully, researchers can find a way to rig microbial battles in favour of these unseen heroes. More research is needed to determine their true potential, but these soil microbes could be called to action in the near future.

    The world under kauri is just one example of fascinating soil microbes. Soil microbes have been found to be key for carbon storage, impact the taste of tea, and reduce nitrogen runoff from agriculture, among many other amazing things. This is your reminder to appreciate the little things, even the things so little you cannot see them. Next time you play in a garden or walk through a forest, I hope you take a moment to think about all the tiny microbes working away in the soil to help (or hinder) plants and make the natural world work.

    This article was prepared by Master of International Nature Conservation student Jodie Wiltse as part of the ECOL608 Research Methods in Ecology course.

    Research Paper: Byers, A.K. (2021). The soil microbiota associated with New Zealand’s kauri (Agathis australis) forests under threat from dieback disease: A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at Lincoln University. Lincoln University. https://hdl.handle.net/10182/13887

  • Farming and biodiversity: what’s on 0.5% of Canterbury Plains?

    Imagine the Canterbury Plains blanketed in tall trees interwoven with small hardwoods. This beautiful, unique landscape is then singed into dry grassland with the arrival of Māori. Continue to imagine European settlers introduce weedy exotics that infest the landscapes, once again modifying the region. Now, picture the current landscape – a monotonous cover of dairy farms. Which of these images would you think is best for our native and endemic species?

    Prior to humans or today? (Think from an insect’s perspective)

    The plains have been a dynamic landscape ever since humans stepped foot in our vulnerable country. They will continue to experience dramatic changes in the future with the ever growing population leading to climate change, urban expansion and agriculture intensification.

    The 1940s saw the commencement of irrigation on the plains so that farmers could have a reliable water source to enhance the production of pasture and crops. Water facilitated the development of dairying from sheep farming, into the landscape we see today. Between 2002 and 2012, the Canterbury herd increased by 115%, accounting for 13.5% of the Aotearoa dairy herd.

    These drastic landscape changes have been detrimental to many of our precious native species by creating unfavourable conditions and habitats, species such as the bellbird (Anthornis melanura) have suffered. Some species, such as paradise shelducks (Tadorna variegata), have exploded in population numbers due to the favorable wet conditions caused from irrigating.

    Within the Canterbury Plains, less than 0.5% of this area is still the original remnant forest. Canterbury has been described as the most biological deprived and most modified environment in Aotearoa due to the intensification of agriculture. However, agriculture is a big portion of the country’s economy, bringing in approximately $10.6 billion (5%) of the country’s Gross Domestic Product (GDP).

    The food and fiber sector are major employer, providing jobs to over 359,000 people. Not only does it feed New Zealanders, it is also a big player in the global food market. in order to come to terms with this environmental dilemma, farms need to incorporate more sustainable agricultural practices, to feed the world and to support biodiversity. Currently through education and awareness this is already becoming a point of discussion.

    There has been a push to introduce native vegetation into farming systems. Several studies have examined the impacts of intensive dairy farming on soil health, vegetation, and life below ground. Farmers are now starting to see the benefits of even simple things, such as planting native vegetation. Such plantings not only positively impact farms, but also our are good for our native species, from small bugs to cryptic skinks and chatty birds.

    Mike Bowie from Lincoln University, like me, grew up on a family farm, and went on to tertiary education in ecology. This brings a helpful perspective to topics around the interaction of agriculture and ecology. It led Bowie to check out the biodiversity in the Bankside dryland remnant that is surrounded by an intensive dairy farming landscape. The Bankside Scientific Reserve in a 2.6-hectare area established in 1969. Mike wanted to know how adjacent agricultural land impacts the soil composition and fauna in this reserve area.

    Aerial photograph of the Bankside Scientific Reserve with kānuka and matagouri dotted throughout. (From Bowie et al., 2015)

    In 1970, an initial vegetation survey was conducted by Molloy within the new reserve. Bowie’s survey in 2015 found that only 31% of plants that Molloy surveyed still remained and that 27 new exotic species were present. The fauna found in the remnant were different to that of the neighbouring agricultural land. Bowie discovered the presence of four native earthworm species along with six exotic species. The number of the exotic worm species decreased with distance into the reserve.

    Bowie and his fellow researchers found 112 specimens of invertebrates, including many beetles as well as a significant native species, the ground weta! Soil pH, nitrate, and phosphate levels were all lower in the reserve compared to the surrounding paddocks.

    These observations highlight the need to retain existing dryland remnants and to establish other reserves throughout the plains. A diverse landscape will support a diverse range of species. I think farmers and the community are now starting to see the value of incorporating native vegetation and agroecological principles into their system, such as mixed species pasture systems.

    We don’t all need to put three hectares away into a reserve. Even small steps, such as planting a row of diverse natives along a fence line or waterway, will make a huge difference, if many farms join in.

    One thing that is highlighted in this study is the need for continued maintenance of restoration and remnant projects. It is not a plant and leave situation (no pun was intended…). Weed and pest control should be continually applied in these areas to prevent exotic weeds and animals from becoming established and smothering and displacing the natives.

    An example of this is in practice Te Ara Kakariki group that is establishing green dots (tiny native areas) from the Southern Alps to Lake Ellesmere/Te Waihora on private properties. This increases the connectivity of native planting, further increasing the power that these small areas can make overall. Animals and invertebrates will be able to spread throughout these dots and over the region.

    Farming has transformed the landscape of the Canterbury Plains. Image from Adrian Paterson.

    Farmers are becoming more aware of sustainable principles through education from organisations such as Te Ara Kakariki, DairyNZ, Landcare trust, and councils. Through education, ecology is becoming more interwoven into their practices. It will be a trick balancing the need for feeding the world and protecting the environment. Ecology is an excellent way to find this balance in agriculture, it can be adapted to any farming system to suit their needs and desires.

    Mike wants to help bridge this gap, not only in this study, but also others that he has conducted throughout his time at Lincoln University. Mike has examined how native plantings encourage native and beneficial invertebrates on Canterbury dairy farms, plus many more. I too believe that ecology and agriculture can work together to create a more sustainable agriculture sector that can efficiently produce food and improve food security, whilst supporting the health of the soil, water and biodiversity.

    This article was prepared by Master of Science postgraduate student Sam Fitzgerald as part of her ECOL608 Research Methods in Ecology course.

    Further reading

    Practical guide for landowner and farmers for landcare

    Improving biodiversity – Beef + lamb