EcoLincNZ

Category: ecosystem services

  • Our plants are not being poisoned by 1080 possum baits

    Our plants are not being poisoned by 1080 possum baits

    I’ll admit, before taking the 16 hour flight from Arizona to Christchurch, I didn’t know much about New Zealand besides ‘What We Do in the Shadows’, Karl Urban, and affordable yarn. I was especially excited to get my hands on possum yarn.  

    Possum yarn is coveted by the knitting community for its lightweightedness and warmth, only surpassed by the fur of arctic foxes and polar bears. And let me say that I absolutely think that the possum yarn was worth every dollar. With just 400 meters (one skein/ball) I was able to knit up a cabled hat, mittens, and still have some left over for some ankle length socks!  

    The feeling of possum yarn is incredibly soft and the natural brown color of the possum fur mixed with merino sheep wool makes for a more muted (in a good way) color palette. However, I recognise that the brushtail possum is a prevalent pest in New Zealand; so much so that drastic measures like Compound 1080 poison baits have been used since the mid-1950’s to control this introduced species. 

    Common Brushtail Possum by Catching The Eye, 2014 (CC BY-NC) 

    Compound 1080 for pest control in New Zealand 

    To put it simply, sodium fluoroacetate (AKA Compound 1080) is a vertebrate pesticide used to control introduced mammal species, such as rats, mice, feral cats, and possums. Without Compound 1080, these species decimate the population of endemic plants and animals only found in New Zealand. The compound is dispersed by aircraft(i.e. helicopters or fixed-wing planes) in either a carrot or cereal bait.  

    According to my professors, everyone has an opinion on the use of 1080. While Compound 1080 is great when it works, there are concerns from both the general public and Māori communities. From a public perspective, 1080 does have the real danger of killing people’s cats and dogs if accidentally ingested. As a pet owner myself, this is especially scary because my cat and dog would likely eat the bait before I’d have a chance to recognise what it was. Additionally, the Māori community has concerns about Compound 1080 leaching into the soil and then poisoning plants used for food or medicinal purposes.  

    Back in September 2003, a cooperative effort was made in New Zealand by the Ecology Department at Lincoln University, Landscape Research, Lake Waikaremoana Hapu Restoration Trust, and the Tūhoe Tuawhenua Trust to determine if Compound 1080 negatively impacts plant species used by the Ngāi Tūhoe Māori and if not, how to get this information spread among the iwi. To achieve this, a study was conducted on wild-growing pikopiko (AKA hen and chicken fern) and Karamuramu plants in State Forest Block 100, just south of Lake Waikaremoana. 

    Hen and Chickens Fern – Asplenium bulbiferum by John B, 2016 (CC BY-NC) 

    Ten individuals of each plant species were chosen and placed underneath wire mesh as protection against herbivory. Of the twenty plants, 3 of each species were exposed to a single Whanganui No. 7 cereal 1080 bait. Samples were taken from the plants throughout the study (days 0, 3, 7, 14, 28, and 56) as well as bait samples at the very beginning and end, to test for potential shift in potency over time.  

    More than 99% of the 1080 had disappeared from the baits by day 56 and all but one plant sample had no remaining amounts of 1080 within their systems. Of the twenty plants sampled, only one Karamuramu plant retained the toxin; and that was at most 5 parts per billion (ppb) and was completely gone by day 28.  

    Foodweb database 

    Karamuramu plant – Coprosma robusta by eyemac23, 2025 (CC BY-NC) 

    I don’t know about you, but I’ve never been a huge fan of reading scientific articles. They’re always confusing, too long, and to be honest, a bit dry. Sometimes I wish I could, instead, just scroll through a presentation with all the information presented short and sweetly.  

    Oh wait, this article did just that and made up not only a comprehensive food web on the interactions of the forest environment with 1080, but also added hyperlinks to it that opens a PowerPoint!(Note: the article did not include the link to the original PowerPoint, only an image of one of the slides.) Each PowerPoint slide focuses on a single plant or animal species impacted by 1080, the intensity of 1080 impact, and additional reference sources. It’s easy to digest and leaves room for more research if one wanted to do so.  

    Concerns from the Māori community 

    In conclusion, I get why using Compound 1080 is necessary against invasive species, like the brushtail possum and it will likely never impact me on a personal level unless it somehow leaches into a batch of yarn or something. However, I also can understand why the Ngāi Tūhoe Māori tribe are still hesitant as 1080 is still a toxin and we may not know the full impacts. While the decision to use Compound 1080 in the Te Urewera area is complicated, in 2016 those from the Ngāi Tūhoe tribe largely oppose aerial drops since it cannot be controlled.  

    Final thoughts 

    I think it’s important to note that for a 70 kg person to actually die from consuming 1080 that has remained in a Karamuramu plant, (and even in this example the probability of death is only 50%), they would have to eat 28 tons (28,000 kg) of the stuff. And that’s also if the plant is eaten raw, normally it’s boiled in water as a tea and diluted even more. Personally, after reading this I wouldn’t be too worried about Compound 1080 in my plants but I will still leave the risk assessment up to those in the Māori community on an individual level. 

    For now, I will continue to enjoy knitting with the luxurious possum yarn until the pests are eradicated from New Zealand once and for all.  

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

    OGILVIE, S.C., ATARIA, J.M., WAIWAI, J., DOHERTY, J., MILLER, A., ROSS, J.G. and EASON, C.T. (2010), Vertebrate pesticide risk assessment by indigenous communities in New Zealand. Integrative Zoology, 5: 37-43. https://doi.org/10.1111/j.1749-4877.2010.00190.x  

  • Forests from grass: natural regeneration of woody vegetation on hill farms

    Forests from grass: natural regeneration of woody vegetation on hill farms

    If you’ve spent any amount of time travelling around Aotearoa New Zealand, you will have noticed the abysmal amount of forest trees in much of our country. Pre-human New Zealand was almost entirely covered in indigenous forest. You may have heard that statement before, but let’s just appreciate it for a second. 96% of the North Island and 72% of the South used to be lush with native podocarps, hardwoods, broadleaves, and beech trees. 

    Over the course of our relatively short history, we eventually destroyed a massive 14 million hectares of indigenous forest to make way for housing, industry, and farms. We were particularly keen on clearing drier and more arable regions like Canterbury and Central Otago, which have lost nearly 90% of their original vegetation. 

    By 2002, only a quarter of that indigenous vegetation remained. Don’t get me wrong, I like living here, that people can make money here, and I like eating fresh food. But, damn, I also like breathing oxygen…

    Looking around Akaroa Harbour, the hills have mostly been cleared of indigenous vegetation at one point or another since human arrival to the area (own photos).

    In all seriousness, native trees play much more important roles than that. Native forests can protect us from wildfires, help us avoid droughts, increase soil, water, and air quality, reduce erosion, and provide habitat for unique native species that do their part in making all of these ecosystem services available to us. As well as that, the land itself, the rugged forests, and activities like hiking through native trees forms part of our cultural identity, not to mention a reasonable chunk of our tourism industry.

    What’s more, our native forests store an incredible amount of carbon – an estimated 1.7 billion tonnes.

    In order for New Zealand to transition to a low-emissions economy and reach its climate change targets by 2050, we need to plant a lot more trees …up to 2.8 million hectares’ worth. The Productivity Commission suggested that most of this land could come from marginal farmland. As it turns out, there is an estimated 2.8 million hectares’ worth of suitable hill country that could be converted to forest. Hill country is essentially steep slopes at higher altitudes. It’s referred to as ‘marginal’ farmland because the economic gains are quite low compared to other landscapes. Steeper gradients are prone to erosion, and high-altitude climates don’t always lend themselves to agricultural productivity.

    Steep slopes at high altitudes are key characteristics of New Zealand’s hill country (own photo).

    So, how do we go about converting hill country farmland into a thriving native forest? Pedley, McWilliam, and Doscher discuss the factors that we must take into account.

    Hill country revegetation projects are tough for the same reasons as hill country farming is tough, there are costs associated with buying nursery-raised seedlings and then planting on difficult terrain. As Pedley and colleagues suggest, the cheaper alternative is to simply let nature do its thing. Allowing forests to regenerate naturally is a form of passive or minimal interference management (MIM). Landowners, especially farmers, are among the most well-placed in the country to protect and expand our country’s native forest cover, and MIM is an attractive solution to the costs.

    When it comes to revegetating farmland, Pedley and colleagues point out two major considerations.

    One difficulty is that pasture grasses often suppress native seeds from establishing, so it’s important to help the seeds get a head start. The easiest way to do this is with nurse crops, which shade out the grass, shelter the natives, and protect them from browsers (particularly possums and ungulates, like deer and goats). Nurse crops can be exotic or indigenous shrubs and trees, and even existing weeds, like gorse, can be made useful. This is because NZ natives generally prefer to start out in the shade, eventually growing tall enough to overgrow the nurse crops.

    Next is the issue of livestock that can be detrimental to natural regeneration. It does depend on which livestock species you have and which tree species are regenerating. Cattle can be extremely destructive to new plants, paddocks, and pre-existing vegetation. Sheep, on the other hand, don’t really seem to make a difference, though they tend to snack on broadleaved species that are a necessity for a healthy forest ecosystem.

    Cattle should be reduced or excluded entirely from a revegetating area. Sheep can be reduced or excluded until there are a good amount of established seedlings, which usually aren’t as palatable to them. Just don’t forget to also keep out those pesky possums and unwelcome ungulates.

    Cattle can be destructive to pastures and newly planted vegetation (“Cow Path to the Forest” by Tristan Schmurr, CC BY 2.0)

    The most important part of natural regeneration is that the seeds have to come from somewhere. This means that the existing native vegetation on your property is one of your most important assets. This is the ‘passive’ part of the process and the money-saver, because you won’t need to buy seeds or establish nurse crops – the trees have got it covered. The native trees will shade out the grass in the space directly adjacent, enabling the seeds to gain a foothold and gradually expand the forest. Fencing off this area, or the paddock the trees are in, is enough to start the process.

    A fair warning though: promoting natural regeneration with MIM can be slow, particularly through grazed pasture. Pedley and colleagues detected an annual regeneration rate of 0.2% from 2003 to 2019 at a southern Banks Peninsula station. At a time when New Zealand desperately needs to plant more trees, MIM is one of the ways landowners with limited resources can contribute, though more active management strategies will speed up the process. For example, consider pest management to exclude browsers (e.g. trapping, hunting, or fencing) and supplementary planting, especially if your remnant vegetation is limited to a few individual trees or species.

    Policy and the barriers to getting involved

    Finally, especially for those of us in the political and conservation sectors, I think it is our responsibility to encourage native tree planting among landowners, while understanding their barriers to doing so.

    The most obvious barrier in converting farmland to forestry is the loss of income, however minor it is. Landowners meeting certain land and forest requirements may be eligible to participate in the New Zealand Emissions Trading Scheme (NZ ETS). With one hectare of ten-year-old forest, you might earn anything from 8-24 NZU per year, depending on the tree species. If sold at $58 per NZU, that’s an annual income of $464-$1392 per year – for essentially leaving the land alone. These figures grow as the forest matures, and with better policy, these figures could grow even more.

    Our policies currently favour exotics over natives, and plantations over constantly-regenerating forest. Not all models consider the amount of carbon stored in the forest understory, which is much denser and richer in a native forest compared to a pine forest. New evidence shows that native ecosystems store much more carbon than previously thought, and over a much greater period of time than pine species.

    Mature beech forest understory (own photo)
    Mature pine forest understory (“Mount Thomas pines” by Jon Sullivan, CC BY-NC 2.0)

    Another barrier to entry is our individualistic culture around climate change action. Many sheep and beef farmers report that pro-biodiversity action is not necessarily about a lack of resources, but the belief that their actions don’t benefit their own farms, or that they aren’t helpful in the bigger picture. It’s important that we change this mindset, because 89% of New Zealand’s emissions are created by our primary industries.

    MIM cuts costs, but adding more trees to your property and protecting them not only benefits the landowner and the immediate environment, but also the rest of the country. It benefits the natural resources on which we all rely, stabilises the landscape, and protects us from fires and droughts. Natural regeneration of natives results in improved biodiversity outcomes, with higher richness and abundance of plants, birds and invertebrates, which not only make all of this possible, but also make the system sustainable. This means that landowners can cut costs in the long run by working with nature, using its natural characteristics and processes to their advantage.

    In any case, growing a forest on a farm is not an overnight process

    It requires a lot of patience, but those who are able to encourage native regrowth are safeguarding the country’s biodiversity and resources for all of us, and contributing to our sustainability. Native forests hold a much more strategic long-term position in the bid to plant more trees, and hill country farmers are the most well-placed to allow their regeneration.

    Perhaps one day we will have the privilege of living and working alongside the lush and bustling forests that once supported us, as we learn to support them.

    Mature beech forest (own photo).

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

    Based on the article by Pedley, D., McWilliam, W. and Doscher, C. (2023). Forests from the grass: natural regeneration of woody vegetation in temperate marginal hill farmland under minimum interference management. Restoration Ecology 31:3. https://doi.org/10.1111/rec.13852

  • 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.

  • Why don’t restored streams bounce back?

    In New Zealand, many would agree that fresh water is one of our most loved natural resources. We drink it, we swim in it, we use it to farm and to make a living, we even use it to generate our power! Unfortunately, especially in Canterbury after some major earthquakes, many of our streams and rivers are struggling. They look something like this:

    Kowhai River, Kaikōura. From Environment Canterbury, ND.

    In stream restoration, we want to return the features of a stream back to their original state, before things like urban development or introduced species affected the quality. This includes adding native plants, allowing fish to make their way out to sea or further upstream, and making sure farm animals can’t walk straight into the stream. All of these things and more can help us to make healthier waterways.

    It does not always go to plan, with some hardy introduced species putting a spanner in the works and refusing to co-operate with careful scientific methods. Imagine a beautiful stream that’s been through tough times—pollution, habitat destruction, earthquakes you name it. People step in – scientists, council members, developers, maybe the general public, and they work hard to restore it, but here’s the kicker: sometimes, things just don’t bounce back like they should. Why? That’s exactly what a recent study by Issie Barrett and her team set out to uncover.

    To understand why streams struggle to recover even after the most thorough restoration efforts, we need to understand a few key factors.

    1. Species Interactions: In a healthy stream, different plants and animals interact in specific ways, such as some animals eating others or different plants competing for space. When a stream is damaged and then restored, these interactions might not work the same way anymore. This can make it harder for the original species to come back and thrive.

    A particular species of snail, the New Zealand mud snail (P. antipodarum) is particularly good at living in these degraded streams, they thrive under pressure and limited food sources. These snails are perfect species to take over a degraded environment and reduce the recovery ability! So even when original species are introduced, such as the mayfly, the same food source now has double the competition, meaning a negative reaction – that habitat can’t provide that much food even in a restored state.

    New Zealand mud snail Potamopyrgus antipodarum. Photo Credit Michal Maňas 2014

    2. Negative Resistance: This is a big concept, which in essence means that even when the physical conditions of a stream improve (like cleaning up pollution or adding new habitats), the plants and animals in the stream don’t always come back as quickly or fully as hoped.

    During the stream’s degradation years, new species like the mud snails might move in – kind of like uninvited guests crashing a party. Even after things are cleaned up, these newbies can stick around and hog resources, making it harder for the original gang to make a comeback. This is what they call “negative resistance.” This can happen because the habitat is too degraded for the ideal species to thrive even if they did before.

    3. Resilience Mechanisms: This means the ability of a system to absorb and adapt to change, ultimately returning to the restored ideal. This is where our negative resistance comes into play. If the species or the system is already not functioning as it should, we are going to have a hard time creating a resilient system that can adapt to a changing environment and overcome any future issues.

    For example, a high level of nitrogen could change the make-up of the riverbed so drastically that a species sensitive to nitrates may never repopulate that system. Understanding the relationship between negative resistance and resilience is important for predicting and enhancing any successful restoration efforts.

    What can we do?

    Look at the Big Picture: When restoring a stream, it’s not just about fixing what we can see. We need to think about how all the different plants and animals interact with each other. This includes what nutrients are in the water and what microscopic invertebrates might be living in that water.

    Keep Checking In: It’s important to keep watching restored streams over time to make sure they’re getting better and to fix any problems that come up. If we don’t see an improvement in 5 or 10 years, there must be something else we can do.

    Be Flexible: Sometimes, we might need to change our restoration plans based on what we learn from watching how the stream responds. As scientists we have to be okay with admitting our first idea didn’t work, and then be willing to help come up with a better solution for the future.

    Vegetated drain in Canterbury with optimum riparian planting. Photo credit Jon Sullivan, ND.

    Why it matters

    Overall, there are some pretty complex systems that are at play in stream restoration projects. It is not as simple as putting in some better plants and some bigger, cooler rocks and hoping it will all work out in 10 years. By paying attention to how plants, animals, and the environment all work together, perhaps we can work towards a deeper understanding of the best ways to help our New Zealand streams thrive for many more generations to come.

    I think it would be pretty cool to keep swimming in our rivers and looking for fish in the summer, but next time you go to your local river, have a look and see what plants and other animals would really love to keep living there too.

    This article was prepared by Postgraduate Diploma in Environmental Management student Tayla Cross as part of the ECOL608 Research Methods in Ecology course.

  • 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

  • Creeks spread invasive herbs in New Zealand

    Invasive plants can have a devastating impact on our natural environment.

    What are invasive plants? Put simply, they are non-native plants that spread rapidly within New Zealand and pose a significant threat to ecosystems, agricultural production, or human health. It sounds awful.It is even worse than it sounds.

    Lodgepole pine (Pinus contorta) CC BY by Chris Schnepf, University of Idaho, Bugwood.org

    Invasive plants pose a threat to natural ecosystems as they are often highly competitive compared to native plants. Invasive species also spread rapidly to take over the living space of native plants, alter ecosystem structures, and reduce biodiversity.

    Many exotic plants are invasive, such as lodgepole pine (Pinus contorta) and Scotch thistle (Cirsium vulgare). Invasive plants change the composition of plant communities and affect food webs and ecosystem balance. For example, the introduction of eucalyptus alters soil chemistry and moisture content, affecting the survival of other plants and animals (Mengistu, 2022).

    Invasive plants also impact agriculture and grazing and can cause massive economic damage. Scotch thistle (Cirsium vulgare) can quickly spread and take over farmland, reducing crop yields. Unpalatable invasive plants can compete with pasture grasses, reducing the area of grassland available for grazing and affecting livestock husbandry (Massey Universy).

    Scotch thistle (Cirsium vulgare) CC BY by John Barkla,  

    Some exotic plants are harmful to human healthy, like Giant Hogweed (Heracleum mantegazzianum),  which can cause third-degree burns and even blindness by simply touching it!

    Knowing how invasive plants spread can help us to control them effectively. A study conducted at Lincoln University in 2013 focused on whether creek habitats are a source of spread for these invasive plants.

    Researchers from Lincoln University (Alice Miller and colleagues) studied Hieracium lepidulum (Asteraceae), an invasive herbaceous plant that has proliferated in the South Island in recent decades. It now occurs in a wide range of upland habitats, from improved short tussock grasslands, to intact beech forests, to alpine herbaceous fields. Hieracium is a more shade-tolerant relative of the widespread pasture hawkeed.

    Historical data suggests that Hieracium is common in naturally disturbed habitats, such as stream edges and forest canopy gaps. Alice selected creek catchments in the area with the longest known history of  H. lepidulum invasion in New Zealand:  Craigieburn Forest Park on the eastern side of the Southern Alps, Canterbury, New Zealand. She surveyed 1,144 spots along 17 creek catchments.

    Giant Hogweed (Heracleum mantegazzianum). CBS News

    Alice and colleagues found that creek habitats (e.g., stream edges and disturbed areas) play an important source role in the dispersal of H. lepidulum. These areas tend to be subject to more natural and human-caused disturbances, which provide a suitable growing environment for  H. lepidulum, and contribute to its rapid reproduction and accumulation in these areas.

    The high resource availability and frequency of disturbance at stream edges allow H. lepidulum to colonise and spread rapidly. Disturbed areas, such as forest clearings and trail edges, provide similarly favourable conditions. Stream habitats provide connected linear dispersal paths that allow H. lepidulum to spread rapidly along streams and from there into neighbouring areas.

    The dispersal patterns of H. lepidulum in forests and subalpine areas were found to differ. In forests, the dense canopy and ground vegetation form a natural barrier to the spread of this plant. As a result, the density of H. lepidulum in forests decreases rapidly with increasing distance from creeks, except in areas with higher light availability, such as tree-fall gaps.

    Forested areas near creek edges remain vulnerable to invasion. In contrast, in subalpine habitats, H. lepidulum density declined more gently with increasing distance from creeks. This suggests that these areas are less restricted to seed dispersal corridors and more susceptible to invasion.

    Location of study area with the 17 surveyed creeks in bold and indicated by an asterisk. From Google Map

    The study also found that multiple environmental variables had an effect on H. lepidulum abundance, with dense canopy cover reducing light and inhibiting its growth. Areas closer to stream mouths were usually more frequently disturbed and H. lepidulum abundance was relatively higher. Higher elevation areas pose a challenge to H. lepidulum growth due to harsher climatic conditions, but the invasion is still significant in subalpine areas. Disturbances, such as human activities, increase the chances of reproduction and dispersal of H. lepidulum.

    Alice provided several recommendations for managing and conserving areas affected by H. lepidulum. First, she suggested prioritising efforts to limit the spread of this invasive plant by reducing disturbances in the environment and using biological control methods. Second, she recommended setting up monitoring systems in vulnerable subalpine habitats to detect and control H. lepidulum early and prevent it from forming large populations. Finally, while disturbances are natural in these ecosystems, it is important for managers to consider the additional impact of human activities, such as building roads and trails, which can exacerbate the invasion, especially in subalpine areas where the barriers to invasion are lower.

    Hieracium lepidulum Stenstr. (Asteraceae).CC BY by John Barkla

    Through this study, we have gained valuable insights into the dispersal patterns and environmental impacts of the invasive plant H. lepidulum. This hardy invader tends to thrive along creek margins and in disturbed areas, making these locations hotspots for its spread. It is our responsibility to protect these pristine landscapes from invasive species.

    If you’re hiking in New Zealand’s stunning mountains, keep an eye out for those little H. lepidulum spreading on the sly. Let’s be the guardians of nature and protect this pristine land from these “little invaders” that are taking over our ecosystem.We can help preserve the natural beauty and biodiversity of New Zealand’s ecosystems, ensuring that these “little invaders” do not take over and disrupt the delicate balance of our environment.

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

    References:

    Mengistu, B., Amayu, F., Bekele, W., & Dibaba, Z. (2022). Effects of Eucalyptus species plantations and crop land on selected soil properties. Geology, Ecology, and Landscapes, 6(4), 277-285. https://www.tandfonline.com/doi/full/10.1080/24749508.2020.1833627

    Miller, A. L., Wiser, S. K., Sullivan, J. J., & Duncan, R. P. (2015). Creek habitats as sources for the spread of an invasive herb in a New Zealand mountain landscape. New Zealand Journal of Ecology, 39(1), 71-78. https://www.jstor.org/stable/26198696

    massey.ac.nz/about/colleges-schools-and-institutes/college-of-sciences/our-research/themes-and-research-strengths/plant-science-research/new-zealand-weeds-database/scotch-thistle/

    https://www.cbsnews.com/news/giant-hogweed-plant-causes-blindness-third-degree-burns-discovered-in-virginia-other-states/

  • Fire-resisting superpowers in plants

    I don’t know what you like to eat at barbecues, but I like some nice roasted veggies! What I don’t fancy are burned broccoli or charred cauliflower. Who would want to eat that, right? Do you have an idea what causes huge amounts of burnt veggies each year? It’s wildfires!

    Seasoned vegetables,
    by polaristest (Flickr)

    With 8-11% of wildfires globally occurring on agricultural land you can imagine that these cause a lot of unenjoyable vegetables. Agricultural wildfires mostly derive from accidental ignition from machinery use or through the escape of fires initially deliberately lit for management purposes. Because 38% of land worldwide is used for grazing and cropping, there is a lot of potential for fire, which highlights the importance of reducing the fire risk to secure our major food sources.

    We don’t have to go far to realise the significance of this topic, as Canterbury accounts for around 20% of New Zealand’s total farmland, roughly 2,600,000 hectares of land. That is about the size of 3,700,000 rugby fields! Canterbury has a climate characterised by low precipitation and dry winds, good ingredients for an easily flammable outdoor barbecue.

    Local wildfires take away many people’s chance to roast their veggies themselves as well as causing a huge amount of economic and ecological loss. But what if we could use farmland for fire prevention? What if some crops actually had the superpower to fight against wildfires, or at least survive them?

    Canterbury NZ, by Simon (Flickr)

    There is a lot of information on how to plant mindfully, using low-flammability plants to create buffer zones that allow us to keep wildfires under control and stop them from spreading. Those ‘green fire breaks’ were tactically planted after the Port Hill fires in 2017 to prevent history from repeating itself. As green fire breaks can only help reduce the impact of wildfires to some extent, planting smart on farmland might add to the best practice, especially in fire-prone areas like Canterbury.

    That is exactly what was tested in a study by Lincoln University in 2023. Masters student Tanmayi Pagadala, with colleagues Azhar Alam, Tom Maxwell, and Tim Curran, tested 47 different agricultural plants for their flammability superpowers, following a simple recipe.

    Ingredients:
    – 47 different shoots and plants of the following groups: cereal crops, forage crops, fruit trees, grazing forbs, pasture grasses, weeds, pasture legumes, vegetables, and wine grapes.

    Utensils:
    – Infrared laser thermometer
    – Lighter
    – Plant barbecue (“a 44 gallon drum cut in half with a grill on top”) 

    Plant barbecue
    (Image by Hanna Hoeffner)

    Instructions:
    – Heat the grill by turning on the burner (125-199 °C)
    – Place your sample on the grill in a horizontal position and leave for 2 minutes
    – Turn on the blowtorch for 10 seconds to ignite the sample
    – Wait until the plant stops burning

    Following this recipe, one can evaluate the ignition time, the maximum temperature reached, the burning time, and how much of the sample was burned.

    After many days of barbecues, Tanmayi’s team was able to tell which plants have the superpower to resist fires better than others. Fruits and cereal crops had significantly higher flammability compared to vegetables, weeds, winegrapes, forage crops, grazing herbs, pasture grasses and legumes. Or, to make it more understandable, easily flammable crops dry faster, are generally dryer, and retain more dead material. Veggie superheroes were bell peppers, spring onions, and potatoes.

    Tanmayi’s team created “A fire-wise mixed cropping farm system” as a guideline for purposeful planting on farmland. The idea of fire-wise cropping is similar to green fire breaks. Using low-flammability native tree, grass and legume species as boundaries around higher flammable crops. 

    Broccoloid, by CaptainEdawardTeague (deviantart)

    Higher flammability species are then protected from wildfires that start outside of the farmland and also prevent fires started on the farm from spreading to neighbouring properties. While you must consider other factors, like local environmental conditions, economics, and goals like enhancing biodiversity, this approach can add to existing green fire breaks. By redesigning farms, we can utilise the fire-resistant superpowers of some species to safely plant non-super-powered plants and minimise increasing the wildfire risk.

    Even though this research was conducted in New Zealand, many of the species tested are common crops worldwide. Therefore, their superpowers could come in handy in many places with continuously increasing fire risks, putting veggies at the forefront of the fight against wildfires!

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

    Pagadala, T., Alam, M. A., Maxwell, T. M., & Curran, T. J. (2024). Measuring flammability of crops, pastures, fruit trees, and weeds: A novel tool to fight wildfires in agricultural landscapes. Science of the Total Environment, 906, 167489. https://doi.org/10.1016/j.scitotenv.2023.167489

  • Fighting fire with farming: flammability of pastures and crops

    The Port Hills are a highly valued geographical feature of Chirstchurch. Located southeast of the city, they are home to a wide range of activities, including rock climbing and mountain biking, as well as being popular among walkers and joggers. Vegetation throughout the Port Hills is varied, containing a range of tussockland, pine forestry blocks, native scrub, farmed grassland, gorse and broom scrub and small pockets of remnant forest.

    On the 14th of February 2024, over 700 hectares of land was ravaged by wildfire in the Port Hills of Christchurch, New Zealand. Over 80 residents were evacuated, and around 130 firefighters with 12 helicopters were involved. Drought conditions and vegetation structure contributed to this event, but could the damage caused by the blaze have been reduced? Could grazing these hills with livestock have reduced the amount of tall dry grass present which fuelled the fire, or could different pasture or shrub species have helped to reduce the flammability of the Port Hills.

    A recent paper from Lincoln University’s own Tanmayi Pagadala, Azharul Alam, Tim Curran and Tom Maxwell has highlighted the differences in flammability between different pasture, crop, weed and shrub species found commonly on farms throughout Canterbury.

    Marley’s Hill on fire. February 15 2024. (Image CC BY-NC by Jon Sullivan)

    A good range of scientific work is available which has investigated the flammability of various plant species in New Zealand, but this has been mainly focused on species in natural areas (both native and exotic), rather than in agricultural environments. Gorse, eucalypts, pines and long grass are well known to be extremely flammable, so why is it that certain areas of the port hills were allowed to return to their same fuel rich state following the 2017 blaze which destroyed over 1600 hectares? It must be acknowledged that efforts were made to replant some of the previously burnt areas in green firebreaks and others in less flammable native species, which were shown to survive the previous blaze in well-established areas.

    Species that regrow following a fire are often also very flammable (eg. gorse and pine). Unfortunately, a significant proportion of the burned land was in pines for forestry, which has since been replanted and will likely create another significant fire risk for the foreseeable future. Continuing the efforts of plant firebreaks of less flammable tree species throughout the Port Hills, as well as within pine forestry blocks, should not be underestimated.

    Individually these breaks may not appear significant, but a thorough network of them throughout the Port Hills could be exactly what is needed to slow the spread of the next blaze and allow firefighters to gain control sooner. Minimising the presence of long, rank grass could also help to slow the spread of the burn.

    Could additional efforts be made in to reducing the presence of long rank grass through the addition of cattle to grazed areas which would trample and eat this dry plant material? Or perhaps planting more drought tolerant, water-efficient forages which can be grazed down during dry periods to minimise the fuel loading of grasslands could be beneficial.

    Dry, rank grass fuelling the blaze on Christchurch’s Port Hills. (Image CC BY Francis Vallance)

    There is a huge range of flammability in different crop and pasture species common to Canterbury farming systems. Assessments carried out on Lincoln University’s trusty ‘plant BBQ’ tested 47 different plant species and varieties common throughout Canterbury farms (see table below), including cereals, forage crops, fruit crops, forage herbs, forage grasses, forage legumes, vegetable crops, weeds and a range of wine grape varieties.

    Unsurprisingly, the majority of forage and pasture species showed very low flammability, as did some vegetable crops and wine grapes. Cereal crops behaved as expected, showing high flammability as they matured and dried off. Surprisingly, apple trees, pears and raspberries showed a high degree of flammability.

    Table of plant species and their relative flammability assessed by Pagadala and colleagues

    The slope of the Port Hills, and an average annual rainfall of 700 mm, means that using low flammability crops like potatoes or peas is not practical. There are, however, a range of pastoral species that show the potential to be beneficial in reducing the flammability of farmland. Forage crops, herbs, legumes and grasses all showed very low flammability scores, which is due to their high moisture content and quality traits meaning they carry very little dead material (the ideal fuel for fires).

    Knowing these flammability scores in addition to the the drought tolerant traits of species, such as lucerne, cocksfoot, red clover, plantain and chicory, raises the question: why are these species currently not implemented throughout the fire prone Port Hills as a method of reducing fire risk? Yes, these forages will become flammable if they are allowed to turn to a reproductive state. However, their drought tolerance and palatability will allow them to be well grazed during dry periods and not contribute to the fuel loading of hills anywhere near the amount that browntop and other native grasses will.

    Chicory next to native pasture in Taranaki. (© Blake Gunn – used with permission)

    The photos above paint a picture of a potential solution to the Port Hills fire woes. At the very least, an effort should be made to ensure that flammable biomass throughout the Port Hills is minimal. Minimising the presence of flammable species, such as gorse and pines, through manual removal or switching to planting less-flammable alternatives, such as native shrubs, are some potential solutions.

    Preventing the planting of pine plantations near the city and other populated areas seems like another fairly logical solution to reducing the fire risk in populated areas, as does surrounding these potential high-risk areas with low flammability and native shrub species. Another area of focus could be to focus more on the management of cattle and/or sheep to intensively graze the hillsides and ensure that a bank of highly flammable fuel does not build up over time. Intensive grazing will not only prevent grass banks from building up, but the ‘hoof and tooth’ activity from grazing may also prevent other flammable species, such as gorse and broom, from re-establishing.

    Lucerne transforming a Central Otago farm system (© Allister Moorhead – used with permission)

    Functional firebreaks could also be of huge benefit to these hillsides. In areas where tractor access is possible, consideration should be given to the establishment of drought-tolerant, low-flammability species, such as red clover, chicory, or lucerne. These will create ‘green zones’ throughout the hillsides that could slow the spread of the next inevitable fire, especially compared to the current vegetation which is prone to turning to a dry, reproductive state over summer.

    To wrap up, logic suggests that previous fires in 2017 and 2024 on the Port Hills, in combination with the presence of flammable vegetation, make another blaze in the future almost inevitable. The findings from recent research on the flammability of pasture and crop species commonly found on Canterbury farms, combined with modern grazing regimes present a real opportunity to significantly reduce the fire risk on the Port Hills. The use of firebreaks planted with native, low flammability species around high risk areas such as pine forestry blocks, along with the protection of existing pockets of native scrub/forest should also help to reduce the fire risk on the Port Hills.

    This article was prepared by Master of Science postgraduate student Kaylee Spain as part of the ECOL608 Research Methods in Ecology course.

    Reference article:
    Pagadala, T., Alam, M. A., Maxwell, T., & Curran, T. (2023). Measuring flammability of crops, pastures, fruit trees, and weeds: A novel tool to fight wildfires in agricultural landscapes. Science of the total environment, 906(1). https://doi.org/10.1016/j.scitotenv.2023.167489

  • Sounds idyllic

    As a kid I explored the waters of the Marlborough Sounds. I caught my first fish there at seven years old and, one New Year’s day, my biggest snapper weighing about 25 pounds. I have been awed by watching fish and bird feeding frenzies- the food chain in practice. I learnt to dive off boats in emerald waters and spent many evenings watching the sunset and roasting s’mores at an isolated and tranquil DOC campsite. A place we call our “bach”.

    But I have never seen a Southern Right Whale, nor an Elephant Seal, or a Waitaha Penguin, in the Marlborough Sounds. Prior to my childhood it was a different Marlborough Sounds. Stephen Urlich and Sean Handley delve into the historical changes of this beautiful location, exploring how food webs have been disrupted since human settlement. The aim of the study was to address knowledge gaps by taking an integrated approach to examining how land use has impacted on coastal ecosystems.

    Stephen and Sean focused on keystone species. They traced the history of whaling in Port Underwood, within the Sounds. When John Guard’s first whaling ship entered the harbour in 1828, whales were abundant. Sadly, by 1836, there were 18 vessels sending out 70 whaling boats to chase these majestic creatures. Whaling led to a significant transformation of the Sounds’ ecosystem.

    Image by Author- Out in the Sounds

    Keystone species, like the Southern Right Whale, play a crucial role in transferring energy within the coastal food web. Their role as ecosystem engineers, essential for habitat formation, was lost by human greed. Sadly, as the authors remind us, the Southern Right Whale was not the first animal hunted by humans in the Sounds. During Maori colonisation, the Elephant Seal, New Zealand Fur Seal, New Zealand Sea Lion, and Waitaha Penguin were all harvested. Hunting led to the decline of the Fur Seal population and the local extinction of the Sea Lion, Elephant Seal, and the Waitaha Penguin.

    What is happening to our waterways? Who is responsible for the ongoing transformation of precious natural environments? Us. Once the habitats of the Marlborough Sounds flourished. The study highlights that in the past, there were various subtidal habitats formed by species such as giant kelp forests, as well as communities of hydroids and sponges. As early as 1863 there was dredging for oysters in the Tory Channel and trawling began in 1904. Both of these disturbed the habitat and permanently changed the landscape. Since the 1970s, commercial enterprises of dredging for subtidal green-lipped mussels has been destroying these habitats.

    The destruction has continued into my lifetime. For example, in the dramatic 2021 floods , my friends bach slid down a hill. A shocking destruction of a home filled with memories. But the hidden impact of mud slides is far more devastating. Mudslides cause excessive amounts of brown sediment to be displaced from the land, settling in the Sounds and leading to extensive physical disturbance to vulnerable habitats.

    Image by Author- Commercial Mussels Farms

    But why so brown? Once Europeans arrived the Sounds continued to change. By the 1970s pine plantations had become widespread and clear felling had begun. Harvested and existing forest makes up about 18% of the land surface in the Marlborough Sounds but contributes to around 65% of landslides in 2021 and 2022 (Hart, 2023). Over the last 50 years sediment accumulation rates skyrocketed and continue to remain elevated. This is seen clearly in the Havelock estuary, which increased soft mud habitat by 34 ha from 2001 to 2014. Steep indigenous forested areas also receive this rainfall but are unrepresented in the slip data.

    The idea of ecosystem-based management (EBM) is also promoted by Urlich and Handley as a way of improving the catchment management. The suggested aim for Marlborough Sounds would be to restore ecological functions so that biodiversity can be maintained. Marine protection is an important part of EBM in New Zealand. It helps to protect remaining high quality habitat and can help with the recovery of more diverse habitats. With proper management maybe one day we will be able to see the return of more mussel beds and marine mammals.

    Is New Zealand really ‘Clean and Green’? Maybe on the surface. But what is happening to habitats in places like the tranquil depths of the Marlborough Sounds? The factors impacting marine habitats are often not well understood. Urlich and Handley suggest that the Marlborough Sounds could rather be referred to ‘brown and down’. This is partially due to the fragmented nature of marine management, where various institutions operate at different scales under diverse legislation.

    Image by Author – My campsite “bach”

    Urlich and Handley highlight that the current marine protection of the Sounds is inadequate as there is only one fully protected reserve. The management of habitats outside this reserve has become an ongoing legal issue. Since the 1880s, calls for additional marine protection within the Sounds has been disregarded. Conservation effort in the Marlborough Sounds is extremely challenging. This study highlights the urgent need for transformative changes in the Marlborough Sounds. It is suggested that the EBM needs to focus on managing seabed disturbance, reducing sedimentation and including Matauranga Maori ecosystem-based management. The EBM has the opportunity to change the narrative back to clean and green from ‘brown and down’ by providing innovative management (Urlich & Handley, 2020).

    Now, when I go out in the Marlborough Sounds, where I was once catching multiple snapper, I am now spending days catching absolutely nothing. With hindsight I need to ask myself: was I part of the problem? Recreational overfishing has contributed to a decline in species.

    Additionally, where once I was surrounded by deep blue sea, now it is often a murky mix. It is time for Marlburians, and New Zealanders as a whole, to take responsibility. We don’t want a collapsing, deteriorating ecosystem. We want an ecosystem that thrives. We want to restore ecological resilience. We want generations to come and sit on remote beaches in the Sounds, benefiting from a thriving ecosystem.

    This article was prepared by Applied Science Postgraduate Diploma student Hannah Smit as part of the ECOL608 Research Methods Class. 

    Urlich. S.C., Handley. S.J. (2020). From ‘Clean and Green’ to ‘Brown and Down’: A synthesis of historical changes to biodiversity and marine ecosystems in the Marlborough Sounds New Zealand. Ocean and Coastal Management. https://www.sciencedirect.com/science/article/pii/S0964569120302593 

    Hart, M. (2023). Human activity a ‘dominant factor’ in Marlborough Sounds Slips. https://www.rnz.co.nz/news/ldr/494507/human-activity-a-dominant-factor-in-marlborough-sounds-slips 

  • Climate change and biodiversity: predicting impacts of the sixth mass extinction

    It is widely known that some 66 million years ago an asteroid hit the Earth, contributing to mass destruction and extinctions, most popularly of the dinosaurs. But did you also know that a very common animal class, birds, are direct relatives to avian dinosaurs? They are literally the only dinosaur descendants. The American Museum of Natural History sheds a light on this, and also names some non-dinosaur animals that persisted through the asteroid impact.

    While tough, thick-skinned crocodiles and alligators surviving may not come as a surprise; frogs, lizards, and some mammals living through the Chicxulub asteroid (with a diameter of 10 to 15 km) impacting with the Earth surely is impressive! If they hadn’t made it through who knows if we would be here today? Those survivors are the origin of our current biodiversity.

    Sadly, this biodiversity is now threatened by one of its own. Many species are going extinct because of us humans. We overuse finite resources, pollute and destroy natural environments to build cities, malls and farms, import invasive species that out compete native ones, … The list goes on.

    There is one really important factor to add here: climate change. By burning fossil fuels, such as coal, gas, and oil, we release gigantic amounts of CO2 into the atmosphere: 37.55 billion metric tons in 2023 alone. The CO2 and other greenhouse gases produced block the escape of heat from the Earth, and our atmosphere becomes warmer. Not only does it become warmer globally, but extreme weather events, such as floods, droughts and storms, become more common, and sea levels rise due to expanding oceans, as well as glacial and polar ice melting.

    Climate change already has a major impact on our planet’s biodiversity. It affects 1,688 threatened or near-threatened species listed in the IUCN red list, a categorisation of the threat status of species, and has been ranked the 7th most important “biodiversity killer“.

    Concepts central to climate change causes and consequences. CC BY-SA, author: typographyimages (pixabay.com)

    Steps are being taken to slow climate change on an international scale, though they haven’t been too successful so far. Governments issue restrictions on emissions produced by industries, promote the use of public transport, and invest in renewable energy production. In 2015, 196 countries signed the Paris Agreement. This created an international plan of action to limit global warming to 1.5°C above the average global temperature in pre-industrial times.

    Even though these measures are being taken, it is likely that climate change will continue to increase in importance for the biodiversity crisis. Measures to limit greenhouse gas emissions will have a delayed impact on the global climate. Thus, the effect of our current emissions will only become visible in 10-20 years‘ time, and in the coming decades, climate change will intensify as a result of past emissions.

    As this is the case, we need to think about what it means for the Earth’s biodiversity. One of the most famous examples of the impacts of climate change on species are polar bears (Ursus maritimus). They only live in the Arctic, which is warming twice as fast as any other region of the world. There, polar bears live and hunt for seals on the ice shelves. Due to higher temperatures, the ice melts and the bears quite literally lose their home and their hunting territory, easily becoming undernourished and sick. To add insult to injury, Arctic warming makes the huge oil and gas fields under the ice more accessible, so that some countries and companies have started exploiting the Arctic. As Greta Thunberg would say, “How dare you?“.

    Polar bears are just one example to illustrate how a species is affected by climate change. Of course, its impacts vary between ecosystems and species, and a polar bear has different challenges to an alpine plant or desert mammal.

    Polar Bear. Creative Commons, author: Andrea Weith.
    Polar Bear eating a seal. CC BY-SA, author: Andrea Weith.

    It has become common for biologists to make predictions on how a species will react to climate change. Historically, only the current climatic conditions of a species’ home range were used to simulate how that range could shift with climate change. Those predictions are then used to inform conservation decisions, which is why it is important that they are as accurate as possible.

    Unfortunately, those conservative models lack a lot of information. If we think back to the polar bears, losing its habitat and hunting range hugely impacts the species, but other associated factors also will influence how they fare in the future. For example, it is predicted that the higher energetic costs of hunting due to climate change will impact female reproduction, and reduce the number and size of healthy litters. Modelling a population with its current demography (its reproductive, survival, and mortality rates), can lead to unrealistic projections, because it doesn’t account for possible future changes to it.

    A study by Urban and multiple colleagues, including Lincoln University’s William Godsoe, looked at ways to improve the accuracy of biodiversity predictions in the face of climate change. They found that including just six biological factors would drastically improve the accuracy of models. Data on the demography of the species, its interaction with other species, its evolution and responses to environmental changes can strongly affect modelling results. So can information on how good it is at dispersing (spreading) as well as its physiology (bodily functions). However, though it may sound easy to include those factors, we lack this data for most species. It is always a challenge trying to make predictions more accurate but lacking data to do so.

    A few strategies can be used to make up for this lack of data. For example, one could focus on modelling the future of keystone species, those that have a more important impact on their environment than others do. Or, researchers could focus on species that are supposedly more sensitive to climate change than others, because if we protect those, others likely also would benefit.

    Unfortunately, with our current knowledge, it is mostly a guessing game to know which species will survive the burden of climate change that we put on the Earth. Though progress has been made, and more integrative predictive models suggested, we still have many questions to answer. Which will be the modern equivalent of birds to the dinosaurs? Or of the crocodiles, reptiles and few mammals that survived the Chicxulub?

    Though predictions always have uncertainty, trying to make the models better by including more information is really important to help us better protect our rich biodiversity!

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

    M. C. Urban et al. (2016) Improving the forecast for biodiversity under climate change. Science Vol. 353, Issue 6304, aad8466. DOI:10.1126/science.aad8466