Category: Uncategorized

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
September 21, 2026
New beetle reveals New Zealand origin story

Beginning the journey

Just before Christmas in 1999, Dr. Eric Scott collected an unusual ground beetle from the Wangapeka Track, in Kahurangi National Park. His wife also suffered a broken arm after a bad fall along the track and Eric safely supported her through the tough walk out for medical care. You will also be pleased to know that the beetle specimen was safely delivered to the Entomology Research Museum at Lincoln University. All in a day’s work for an entomologist!

At that time, no one knew that this tiny beetle would become crucial evidence in a controversial biogeographical debate years later.

Classification work

The scientific name of this newly discovered ground beetle species was Orthoglymma wangapeka (there is no common name). This species belongs to the ground beetle family (Carabidae, Coleoptera). It is quite small, with a body length about the size of a fingernail. The beetle is elongated and narrowed at the ‘neck’ position. Its entire body is covered in a dark brown, polished exoskeleton.

It looks like a normal brown beetle at first glance. However, careful examination of both its external structure and internal reproductive organs, led an international research team, including John Marris and Rowan Emberson from Lincoln University, to discover that this was a new species, different from any other known Orthoglymma species.

Dorsal View of Orthoglymma wangapeka, Scale bar: 1 mm.
Photo Citation: Lincoln University Living Heritage: Tikaka Tuku Iho (6th Mar 2023). Coleoptera Orthoglymma wangapeka Holotype. In Website Lincoln University Living Heritage: Tikaka Tuku Iho. Retrieved 17th Apr 2026 12:00, from https://livingheritage.lincoln.ac.nz/nodes/view/36272, used under CC BY 3.0 NZ

The research team placed the newly named Orthoglymma (from Ancient Greek for straight carved lines – referring to the lined on the abdomen) wangapeka (from the locality of collection) in a tribe called Broscini.

They obtained data on 73 physical traits and compared with closely related beetles. The closest relatives of this species are all found only in New Zealand, Australia, and southern South America. This suggests that the ancestor of these Orthoglymma species was found in these areas. Fossil evidence of Broscini ground beetles in other research suggests that this group originated before the Gondwana breakup.

Ancient biota debate

What is the Gondwana breakup? Based on earth science research, Gondwana was a supercontinent that formed around 600 million years ago. It included many of the current continents, such as South America, Africa, Antarctica, Australia, and our homeland, New Zealand. The supercontinent Gondwana began to break apart around 180 million years ago.

The continent of Zealandia started separating from Gondwana about 85 million years ago, becoming isolated around 70 million years ago, leading to the formation of the Tasman Sea.

The long process of the fragmentation is known as the Gondwana breakup. This history explains why New Zealand’s biology shares high similarities with other southern landmasses, like Australia, South America, and Southern Africa, which were also part of the original landmass and neighbours to New Zealand.

A map of the supercontinent Gondwana. At this stage in the earth’s history, Zealandia had not formed a distinct continent yet.
Photo Citation: Mikocheung, CC BY-SA 4.0, via Wikimedia Commons

A second critical event occurred in New Zealand after the Gondwana breakup. New Zealand experienced a significant rise in sea level due to the sinking of the Zealandia continent around 25 million years ago. This is known as the ‘Oligocene Drowning’ theory.

There has been a heated debate about the extent of this drowning in the academic world. Some experts argue that New Zealand was completely submerged under the ocean during the Oligocene Drowning, which would cause all local terrestrial organisms to go extinct. From this perspective, our current animals and plants would have had to colonise New Zealand by crossing the sea after the drowning. On the other hand, the opposing experts claim that parts of New Zealand must have remained above the ocean, providing a refuge for ancient species to survive.

Beetles and land

Orthoglymma wangapeka is a tiny ground beetle that belongs to an ancient branch that evolved before the Gondwana breakup began. These beetles are flightless, lacking the obvious ability to disperse long distances across oceans. Their ancestors almost certainly were present in the pre-break up New Zealand region of the supercontinent Gondwana. Their presence is a powerful piece of evidence suggesting that New Zealand was not completely submerged in the ocean during the Oligocene Drowning.

The area where Orthoglymma wangapeka was collected belongs to the Buller Terrane, which is one of the oldest rock formations in New Zealand and originated on the eastern margin of Gondwana. The species may be a Gondwanan relict, a survivor of extreme environmental change in this area.

Other ‘living fossil’ are also found in this area suggesting that the Nelson area might have been an island that provided insects, including ground beetles, wētā, and micropterigid moths, with dry land to avoid extinction during the Oligocene Drowning.

View of Wangapeka Track, where Orthoglymma wangapeka was collected.
Photo Citation: Michal Klajban, CC BY-SA 4.0, via Wikimedia Commons

Summary

As an ecology student, I am deeply drawn to this story because it is remarkable that a newly discovered species could play a vital role in a long-standing unsolved debate in earth science.

It fascinates me how a tiny organism can carry such a wealth of information about our country’s ancient past. This case demonstrates how biodiversity research connects with other subjects and provides a priceless value in broadening knowledge and highlights the importance of environmental conservation.

Without conservation of the habitat, this new species could have gone extinct before it was collected, and we would have missed a critical piece to the puzzle to understand the ancient geographical secrets of our country.

Next time you walk a trail in New Zealand (first watch where you are walking – don’t break and arm!), keep in mind that everything that exists in the environment might carry some undiscovered secrets of the earth’s history, even a tiny ground beetle.

This article was prepared by Master’s of Bioprotection student, Ethan Harland, as part of the ECOL608 Research Methods in Ecology course.

References

Liebherr, J. K., Marris, J. W. M., Emberson, R. M., Syrett, P., & ROIG‐JUÑENT, S. (2011). Orthoglymma wangapeka gen.n., sp.n. (Coleoptera: Carabidae: Broscini): a newly discovered relict from the Buller Terrane, north‐western South Island, New Zealand, corroborates a general pattern of Gondwanan endemism. Systematic Entomology, 36, 395-414. https://doi.org/10.1111/j.1365-3113.2011.00569.x

Matt McGlone, Evolution of plants and animals, Te Ara – the Encyclopedia of New Zealand, https://teara.govt.nz/en/evolution-of-plants-and-animals (accessed 23 April 2026). Story by Matt McGlone, published 1 March 2009.

Mildenhall, D. C., Mortimer, N., Bassett, K. N., & Kennedy, E. M. (2014). Oligocene paleogeography of New Zealand: maximum marine transgression. New Zealand Journal of Geology and Geophysics, 57(2), 107-109. https://doi.org/10.1080/00288306.2014.904387

September 9, 2026
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
September 7, 2026
Bellbird Babel: Dialect differences in NZ bellbirds

Bellbirds love to sing; they sing for everything that they do. Communicating, courtship, foraging, defending their homes, it’s almost like they’re living in a musical. I’ve always been captivated by the song of bellbirds. Whether I’m on a walk in the Port Hills, or at Willowbank Wildlife Reserve looking at the capybara and otters, I hear bellbirds singing in the background.

The New Zealand Bellbird, or Anthornis melanura, is a honeyeater species and a close relative of New Zealand’s Tūī (Prosthemadera novaeseelandiae). They have a variable diet, feeding primarily on nectar, but also fruits, insects, and scale insect honeydew. In Christchurch, bellbirds spend their summers in the Port Hills, feeding from the large nectar supplies that come from flowering native vegetation. Then, in the winter, some move to the city, where urbanisation creates a warmer environment, and sugar feeders and exotic plantings provide food.

In 2019, PhD student Jennifer Dent studied foraging and migratory patterns of bellbirds in Christchurch for her thesis, using their calls to determine where different groups were. Bellbirds in different areas make different calls, basically a different accent, language, or singing a song in a different key, and this is referred to as dialect.

New Zealand Bellbird. Photo CC0 Max G.W. Verheij. https://www.inaturalist.org/observations/162255122

For this, Jennifer placed DOC AR4 audio recorders at 59 locations. 29 locations were in the Port Hills, where recording took place in autumn. Sites were everywhere from Rapanui Bush in the east to Ahuriri Reserve in the west, totalling 15 km around the Port Hills. The other 30 recording locations were in Christchurch city during winter, from as far north as the Groynes, as far east as Sumner, and as far west and south as Lincoln. From this, Jennifer matched dialects in the Port Hills in autumn to those recorded in Christchurch city in winter.

Christchurch dialects

Jennifer found four different bellbird dialects in Christchurch.

Dialect A was the most common dialect. It was spread across the northern region of the Port Hills, as well as in more central areas, such as the Botanic Gardens.

Dialect B was the next most common. In the Port Hills, it was found in Kennedy’s Bush, and in the city, it was in south-western areas, such as Halswell and Hoon Hay.

Dialect C was the least common dialect that Jennifer observed. In the Port Hills, it was found in Omahu Bush, and in Christchurch, it was found outside of the city, but only as far as Tai Tapu and Lincoln.

Dialect D was the last dialect. This pattern is unusual because it was not found in the autumn Port Hills recordings, but was found in the winter Christchurch recordings around the eastern and northern parts of Christchurch, such as Sumner, the Groynes, and Riccarton Bush, but because it was not found in the autumn recordings, it is not known where they went after winter.

Map of Dialect Locations in Christchurch. Photo CC-BY Jennifer Dent https://researcharchive.lincoln.ac.nz/server/api/core/bitstreams/82c22265-dec3-419b-8880-4eb37f1aaee2/content

Why don’t the dialects overlap?

It’s surprising that four different dialects were found both so close together and with very little overlap, especially since there are no geographic barriers stopping members of one group from flying to another. Jenny suggested that there could be two main reasons for this: limited dispersal and vocal imitation.

Limited dispersal, or philopatry, is the theory that states that birds remain in the areas where they were born and raised perhaps because it is harder to survive outside their own groups. A second theory is that vocal imitation by bellbirds occurs when birds move between groups, but we don’t notice it because they are so quick to pick up on the new dialect. It is possible that both of these theories are occurring simultaneously.

Following bellbirds into the city

The presence of all Port Hills dialects in the Christchurch recordings suggests that seasonal dispersal from the Port Hills to Christchurch is a shared behaviour among all populations. Furthermore, as shown by the map, dispersing to the nearest suitable location rather than spreading across all of Christchurch also seems to be a shared behaviour.

Bellbirds in Christchurch likely remember foraging areas for different times of the year, but rather than remembering many locations across Christchurch, they remember only a few patches that are close together. This is referred to as patch-scale resource tracking, and it has been shown to be a low-work, high-reward technique for foraging by bellbirds.

Next time you hear a bellbird singing, you aren’t just hearing background noise, you’re hearing a local neighbour. That bellbird might be a Cashmere regular or a member of the Tai Tapu community. It makes Christchurch a more lively city, as it’s not only just a place for us, but for birds following their own routines, singing their songs as they go about their day.

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

Paper reference: Dent, J. M. (2019). Information use during foraging by New Zealand bellbirds (Anthornis melanura) : A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at Lincoln University. Lincoln University. https://researcharchive.lincoln.ac.nz/server/api/core/bitstreams/82c22265-dec3-419b-8880-4eb37f1aaee2/content

September 2, 2026
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)

August 31, 2026
Wasps aren’t all aggressive, just misunderstood

Uncategorized, behaviour, conservation, entomology, student blog, wildlife management

If you had asked me four years ago where I would be today, I would not have said ‘planning to study wasps’, and I would NOT have said ‘New Zealand’! But here I am and that’s what I’m doing.

My interest in this field originates from my research on ants, and more specifically their unique behaviour. Ants belong to the order Hymenoptera, the same order as bees and wasps.

Just like humans, wasps can be social creatures, and just like humans they display different levels of aggression (although most types of wasps are not social). Despite there being around 100,000 described wasp species, only around 1,000 of them are social. Which seems crazy, because when you see one wasp, you always seem to see more.

Vespula wasps are what’s called eusocial, this means that they are organised into groups and all work together under a single queen. Eusociality is impressively efficient. E.O Wilson, a famed ant biologist, once said that humans display a weak form of eusociality, and I have to say I agree with him.

Now, back to how wasps display different levels of aggression. Have you ever noticed that when you walk past a nest or sit near a wasp sometimes you will be harassed while other times they will completely ignore you? That’s because different colonies of wasps display their own levels of aggression!

Vespula germanica, David Nicholls, Ratby garden, 22 April 2016

There are many reasons why wasps may vary in aggression. Some may be more aggressive to drive away predators or outcompete other colonies. Others may be more passive to hide from mammals who could destroy their nests.

A group of brave researchers, including Mateus Detoni from Lincoln University, put themselves in harm’s way to determine what factors cause wasps to display varying levels of aggression.

One hypothesis that they developed was that foraging and temperature could increase aggression because that is when wasps are the most active. The methods used for testing the aggression of the wasps included a target made from two black plastic plates that had been clasped together and a black cloth. Inside the plates was an omnidirectional microphone that had been connected to a camera.

As you may know, wasps are a super invasive pest species in New Zealand. Since the early 1900s they have been having a devastating impact on the beech forests and the native ecosystem as a whole. There are two species in New Zealand Vespula vulgaris and Vespula germanica, both having colonised from Europe in the 20th Century.

To survive, wasps need sugars and protein, so they go hunting. The main thing wasps are foraging for, especially in beech forests, is honeydew. This is a type of sugar that has been pooped out by scale insects, which live on and inside beech trees. The main source of protein for wasps is, well, anything that is soft enough for them to bring back to their nest.

Wasp foraging for honey dew on a southern beech tree. Image from Adrian Paterson.

The study found that, surprisingly, neither foraging activity nor temperature seemed to have any role in indicating whether a colony would be particularly more aggressive than another. So, the researchers turned to the next question, could it have something to do with nest and colony size? Unfortunately, this lead was also a bust. Yes, the larger colony size did allow for higher foraging activity but there was still no indication that a larger nest and colony would increase aggression.

Did aggression have something to do with the age of wasps? Eusocial insect colonies span generations of individuals meaning there are both juvenile and mature workers alive simultaneously. This was a topic that Mateus had previously studied. Age can play a role in aggression, as the older wasps have more experience defending the nest, which can cause them to have a more aggressive response when agitated.

Vespula wasp colonies were observed through their life, and it was concluded that the behaviour on a colony level is consistent throughout development. However, one key thing was noted “behaviour can change as an individual, or colony develops” and “consistent differences within a population can still be observed”.

Aggressiveness could depend on the ratio of aggressive to nonaggressive individuals in the colony. Wasps having their own individual personalities is not something that most people consider, as they are often thought of as all being worker drones. But I guess a lot of that can be attributed to the media shaping how we view wasps, bees, and ants.

In Europe, wasps have predators that both keep the population in check and give them a reason to be aggressive. The researchers suggested that external pressures may cause certain behaviour to be passed down through generations. In a place where they do not have predators, such as New Zealand, they can learn to pass on behaviour that is less aggressive.

Wasps are insects that have individual personalities influencing the aggression levels of the colonies that they live in. Eusociality truly is one of the most interesting concepts in the animal kingdom.

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

Reference:

Jandt, J. M., Detoni, M., Loope, K. J., & Santoro, D. (2020). Vespula wasps show consistent differences in colony-level aggression over time and across contexts. Insectes Sociaux, 67(3), 367–381. https://doi.org/10.1007/s00040-020-00768-3

August 26, 2026
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.

August 11, 2026
It’s not you, it’s your species: Mate choice in fishing spiders

Dating is hard and confusing for most… but especially for these guys.

A recent study on two native semi aquatic spiders, Dolomedes aquaticus and Dolomedes minor, revealed that spider dating is dramatic, but beneficial for their evolution. These spider species spend a lot of time diving for their prey in rivers and streams.

Male fishing spiders (Dolomedes species) perform complex courtship displays for their partners, which include vibratory, visual, and chemical signals, all just to avoid being killed by the female they are trying to impress, and just so he gets the opportunity to copulate.

D. aquaticus at Boyle River. Photo by Nicky Lowther (CC BY-NC)

Unfortunately for these eight-legged boys, their ladies are often aggressive, sexual cannibalism common, and dates often making up a significant portion of these feisty ladies diets.

These fishing spider species are found throughout New Zealand. In a particular area in the lower South Island, something interesting is going on… they are hybridising!… but only in one direction.

DNA analysis has revealed that mitochondrial introgression has occurred between D. aquaticus females and D. minor males. Introgression is when DNA moves from one species to another. But why, and why only one way? This study investigated the one way introgression between these two species, coauthored by one of New Zealand’s preeminent arachnologists, the one and only Cor Vink.

These species are closely related and have been observed to interbreed. This causes genes from one species to pass to the other; this process is called introgression. Introgression between these species has only been observed in one direction between female D. aquaticus and male D. minor. Introgression has also only been seen in one location, in the south of the South Island, the “introgression zone.”

Distribution of Dolomedes aquaticus and D. minor within New Zealand, with introgressed D. minor specimens shown. Data from Vink and Dupérré 2010 and Lattimore et al 2011. Also shows collection locations of spiders for laboratory experiments, and Waipara field monitoring site. The introgression zone is shown by the square box. (Content subject to copyright: please see the study image notes for details)

The purpose of this study was to investigate life history traits and mating behaviour that promoted and limited introgression that occurs only one way and is limited to one area.

Spiders were collected from within and outside the introgression zone and mating behaviour was tested in a lab.

From these experiments, it was found that males from outside the introgression zone were less willing to continue courtship once realising the female was of a different species from themselves, often ghosting halfway through, an experience familiar to those of us in the dating pool. On the other hand, D. minor males within the introgression zone were happy to flirt with any female. This unfussy selection seems familiar. Whether this is a spider phenomenon or a southern cultural trait remains unclear.

Another interesting find was that female D. minor were more short tempered when it comes to D. aquaticus males, having much higher attack and rejection rates towards D. aquaticus males than the opposite pairing. When a D. aquaticus male attempted courtship, the females often attacked and ate him. This suggests the differences in female behaviour between the two species may have just as much influence on gene flow as mate choice.

Female receptiveness to male courtship is key for introgression to occur, including female ability to recognise male courtship, female choice, and premating aggressive behaviour, these could all prevent interbreeding in ways that could vary throughout the species’ range.

Pairings were more successful if the pairings were similar in size. Females in both species are much larger than males, although D. aquaticus is larger overall. It was suggested that one way introgression could be because a female D. aquaticus assumes that a smaller male would be an easier snack, not a great mate!

D. aquaticus at Boyle River. Photo by Nicky Lowther (CC BY-NC)

Other potential factors could include that partners in the south could be less choosy in their mate selection as their breeding seasons may be shorter due to natural conditions. D. aquaticus females may think males of their species are rarer, or D. aquaticus male and D. minor female genitalia may not be compatible.

In summary, it is likely that mating behaviour has a strong influence on the dynamics of introgression gene transfer between these species within the introgression zone.

Male behaviour may limit introgression one way, preventing mating between D. minor females and D. aquaticus males. Also, female behaviour and choice may limit introgression because of a preference: mate or meal?

In the end, these spiders prove one thing: rejection is natural selection, and preference is important in evolution. So, next time you have a bad date, consider yourself grateful that your rejection did not end in sexual cannibalism. 🕷️

This article was prepared by Master of Bioprotection student Nicky Lowther as part of the ECOL608 Research Methods in Ecology course

Connolly, S. J., Hunt, J., Curtis, K. M., Painting, C. J., Cooney, C., & Vink, C. (2025). Mating behaviour influences the direction and geographic extent of introgression in New Zealand fishing spiders (Dolomedes). Journal of Evolutionary Biology, 38(3), 291–304. https://doi.org/10.1093/jeb/voae147

August 5, 2026
The shrubland invasion: What’s driving it?

Plant communities dominated by mānuka/kāhikatoa (Leptospermum species)or kānuka (Kunzea species) are an extremely common feature of New Zealand’s native biodiversity. They are found in all manner of shapes, sizes, and habitats – dry and wet, high and low, warm and cold. We’ll call these communities ‘shrublands‘ throughout this text. Reality is much more complex with other types of native shrublands made up of different plant species as well as kānuka and mānuka also forming forests or scrub. There’s a great piece here if you want some more details.

If you’ve ever bashed through young, dense, mānuka/kānuka shrublands whilst out tramping you might have noticed they aren’t very diverse. That’s because during this young phase they form such a thick canopy and dense shade that other plants find it difficult to establish. Once these stands age the canopy opens up and lets light in allowing other species to take off.

The weed Spanish heath (Erica lusitanica), the lighter yellow-brown plants near the ground, invading gaps in mānuka (Leptospermum scoparium var. scoparium) shrubland on Bealey Spur. Photo Will Todhunter

These shrublands are important for our native biodiversity. Some are remnants from before humans arrived. Others have expanded following human induced forest clearance and subsequent regeneration. These regenerating shrublands are what we call seral, an intermediate stage in ecological succession.

Succession occurs when an intact ecosystem is disturbed and doesn’t immediately go back to its final climax vegetation. Instead subsequent vegetation communities gradually replace one another until a climax, or stable, state is reached. Under the right set of conditions kānuka and mānuka can shade out introduced grass species and support a transition of landscapes back to native forest.

Banks Peninsula has many classic examples of this phenomenon, and if you go for a walk up Bowenvale Valley, in Christchurch, you should be able to spot large areas of planted kānuka where Christchurch City Council is trying to jumpstart this process.

Including these shrubland species, Aotearoa has a grand total of 2,522 native vascular plant species. This total is far outnumbered by the staggering amount of introduced plant species, with at least 24,744.

In many cases introduced plants can establish in the wild and invade natural ecosystems, including native shrublands. We will call these invasive introduced species weeds. These exotic weeds can negatively impact our biodiversity, displacing native plants and changing the ways our ecosystems function. Weed invasion has been well studied in forest and grassland ecosystems in New Zealand, but less so in shrublands. It is important to understand what drives weeds to invade shrublands, as this can help guide us when considering actions to protect these habitats.

Laureline Rossignaud and Philip Hulme are researchers from Lincoln University who focus their research efforts on biological invasions, including weeds. They looked at information from 247 monitoring plots placed within shrublands across the country to better understand weed invasion into these habitats. Many studies have already investigated whether the number of native plant species in an ecosystem is related to weed invasions, but few studies have also considered the influence of climate, landscape features and the structure of the plant community in question. So, when this pair dived deeper into this topic, what did they find?

Both the number of different species (species richness) and the size of the area covered by a species (its cover) play a role, but they don’t always align. Some shrublands had high numbers of species with low cover, whilst others had low numbers of exotic species but these were high in cover. This second example can be seen when a few aggressive weeds dominate.

Shrubland on Banks Peninsula. Photo by Will Todhunter CC BY

Low species richness, high species cover. The above image captures this, showing vegetation in a mature kānuka stand on Banks Peninsula. An open canopy of kānuka sits above a lower tier of native saplings of māhoe (Melicytus ramiflorus subsp. ramiflorus), poroporo (Solanum laciniatum) and kawakawa (Piper excelsum subsp. excelsum), and a dense ground cover of the highly invasive exotic veldt grass (Ehrharta erecta). The veldt grass forms such dense mats that it limits the establishment of most other plants and was once voted NZ’s worst weed!

A clear takeaway from the study was that the physical structure of shrublands plays a big role in determining how susceptible they are to exotic plants. Shrublands with dense canopies and multiple layers of vegetation act like a shield, limiting open ground and leaving less space for weeds. Shrublands with open areas let in more sunlight and have more available options for weeds to gain a foothold.

The surrounding land cover and land use heavily influenced weed invasions. Where shrublands were close to human modified landscapes ,weed invasion increased, and the same when shrublands were close to rivers. Modified landscapes typically had a higher number of weed species, providing a seed source that can then move into more natural areas.

Size and shape of shrublands matters. Shrublands with long edges experienced higher levels of weed invasion, with edges often having more disturbance and being more accessible to invaders. This is known as an “edge effect“. Topography is another contributor, with lower and flatter areas more invaded than those that are steep and/or at higher elevation

Unsurprisingly, climate also played a major role. Warmer temperatures were shown to increase weed invasion, and many introduced plants thrived in mild conditions. The expansion of suitable habitat ranges of weeds through a warming climate is yet another reason to be concerned about climate change!

Scrubland on Onawe Peninsula, Banks Peninsula. Photo by Adrian Paterson

Lastly, these researchers found that no single factor could fully explain weed invasion, it’s all about a combination of various factors. Something that readers might have expected.

Through my work in conservation I’ve been lucky enough to spend time in a range of shrublands. Some of the most special are the fragmented remains of the once extensive kanuka drylands of the Canterbury Plains, such as Motukānuka Scientific Reserve. Research has found that intensive land use change adjacent to these remnants has strongly contributed to increased weed invasion on the edges. Irrigation changing water availability and increased nitrogen availability from surrounding farms were attributed as two of the main drivers here.

There’s a couple things we can learn from these studies when thinking about protecting shrublands. To reduce the impacts of exotic plant invasion, the larger the area of shrubland the better. Dense, structurally rich vegetation is going to be more resilient to invasion. However, often small fragments of biodiversity are all that are left to work with, so factoring in a buffer from surrounding land use then becomes important.

In many situations active management of weeds, such as physical control using herbicide, is essential to protect native species and ecosystem function’s from their impacts.

So now that you know a bit more about shrublands, keep an eye out for some of the features discussed here. Keep learning about the native and introduced plants of New Zealand, and get out there with the right people and deal to some weeds!

This article was prepared by Will Todhunter, Postgraduate Diploma in Applied Science student, for an assignment in ECOL608 Research Methods in Ecology.

Rossignaud, L., & Hulme, P. E. (2023). Native vegetation structure, landscape features and climate shape non-native plant richness and cover in New Zealand native shrublands. Diversity and Distributions, 29(8), 1009–1020. https://doi.org/10.1111/ddi.13713

July 29, 2026
It’s only forever, not long at all

Time has very much been on my mind lately.

To be exact, it is probably the comprehension of time that has been at the forefront.

I just went to the 40th anniversary of the movie ‘Labyrinth’, a quirky movie by Jim Henson of muppets fame, written by Monty Python Terry Jones, and starring David Bowie as the Goblin King (and who also wrote the songs) and Jennifer Connolly in her first role. Essentially a teen babysitting her baby half-brother wishes the goblins would take him when he cries to much. They do and many dream-like twists and turns occur in the goblin labyrinth as Sarah finally outwits the Goblin King to get the baby back.

I was 19 when I went to the cinemas to see this movie. It’s a little intimidating to think that 40 years have passed since that that fresh-faced Adrian was starting his honours year at Otago. In some ways it seems like yesterday, in others a lifetime has passed by. I mean I’ve done a PhD, got married, became a lecturer, raised three sons to independence, supervised 78 postgraduates to completion, travelled, read a lot of Tolkien, listened to a lot of Kate Bush, played a lot of games, coached a lot of cricket and so on.

Adrian in 1989 – starting his research career with behavioural work on native bees. Image by Adrian.

(By the way the movie holds up well, the practical effects are still amazing, the songs catchy, Bowie’s pants are still alarmingly tight, although there are parts that have not aged well, especially the early computer effects – I’d like to think of that as a metaphor for something!)

At a smaller scale, my granddaughter is about to turn one. (Note even the idea of being a grandfather makes me contemplate time a lot!) As an evolutionary biologist I have always said to my classes that, from an evolutionary fitness point of view, becoming a grandparent is the goal – you have reproduced and your children have reproduced. There’s not much more that you can do.

I’ve also found that being a grandfather is a wonderful job in its own right! It feels like the most important thing that I could be doing. So yah for evolution!

The last year has whizzed by and granddaughter has changed from an organic lump into a moving, noise-making, interactive Individual. Biology is amazing. But where did that year go?

The perception of time is a funny old thing. With regards to my granddaughter the last year has sped by. On the other hand, I got a bad concussion last January (I zigged when I should have zagged) and the recovery from that, still ongoing, seems to have taken a decade. Same period of time but contrasting experiences!

Adrian in 2026 with granddaughter. Image by Julie Paterson.

Our poor human perception of passing time can really get in the way of understanding science, especially the sciences that take place over long periods, such as evolution, geology, astronomy. A particular issues is getting our minds to comprehend just how much time there has been.

In my teaching I have used several analogies to try and get across the sheer scope of time. You want to take something familiar and use that as a metaphor. I’ve walked around the classroom where every step is 50 million years, I’ve used a rugby game where every minute is 25 million years. Usually, I am trying to emphasise that the dramatic stuff that we are most interested in happened recently and a looooooong time from the beginning.

So here I go again trying to give a sense of the time available for the history of the Earth! This time let’s think about ‘The Lord of the Rings‘. Most people know the basic story: Bilbo gives Frodo a magic ring which turns out to be the source of the Big Bad of the world’s power that must be destroyed in the volcano where it was made. Shenanigans ensue.

So, lets say we start with Chapter one and finish when the hobbits destroy the ring at Mount Doom (I know there is a prologue and there are several chapters after this but let’s stick with this basic journey of Shire to Mordor). In my copy of the ‘The Lord of the Rings‘ (LotR)this part of the story takes 916 pages. If the Earth forms with the first sentence of Chapter 1 “When Mr Bilbo Baggins of Bag End announced…” we are at 4.5 billion years ago.

Each subsequent page is then the equivalent of 5 million years (still a period of time that is unimaginably long!).

First evidence of life on Earth appears around page 54/916. In our read through of LotR this is in the The Fellowship of the Ring – Three is Company where Sam and Frodo meet Gildor and the elves within the Shire as they camp after leaving Bag End.

“Before long the elves came down the lane towards the valley”

Prokaryote fossils (bacteria) appear in the fossil record around page 114/916 where Tom Bombadil rescues the hobbits from the clutches of a barrow wight. (The Fellowship of the Ring – Fog on the Barrow Downs)

“At these words there was a cry and part of the inner end of the chamber fell in with a crash.”

We finally see complex cells (eukaryotes) – the kind that would lead to you, me and the trees over half way through on page 503/916. Gandalf and Aragorn are talking to a defeated Saruman in the wreck of Isengard (The Two Towers – The Voice of Saruman).

“They came now to the foot of Orthanc.”

Note that we have missed the hobbits fleeing the Nazgul and the Shire, Rivendell, the Mines of Moria, Lothlorien, Boromir’s death, the breaking of the Fellowship, Gollum, Ents, Rohan and Helms Deep!

Gollum by Julie Paterson

Multicellularity, sticking more than one cell together to form more complex organisms occurs on page 709/916. Pippin and Gandalf have ridden to Gondor and are meeting with Lord Denethor (The Return of the King – The Siege of Gondor).

“Before long he was walking with Gandalf once more down the long cold corridor to the door of the Tower Hall.”

The Cambrian Explosion, a point in time where we see fossils suddenly appear for almost all modern groups happens on page 803/916. We have sped past the journeys with Gollum, the encounter with Faramir and the Oliphaunt, and Gollum’s betrayal of the hobbits to Shelob and arrive at Sam rescuing Frodo from orcs after he has been poisoned by the spider (The Return of the King – The Tower of Cirith Ungol)

“At that rage blazed in Sam’s heart to a sudden fury.”

Land is colonised by plants and animals on page 833/916.The siege of Gondor is in full swing and Denethor perishes in a bonfire meant for the wounded Faramir (The Return of the King – The Pyre of Denethor).

“Gandalf in grief and horror turned his face away and closed the door.”

Reptiles, particularly lineages leading to dinosaurs become dominant by page 847/916 (The Return of the King – The Houses of Healing). Aragorn, Gandalf, Pippin and the wounded Merry reunite after the Battle of the Pellenor Fields where the Mordor forces have been beaten back and the Witch King destroyed.

“And get the pipe out of my pack, if it is unbroken.”

The extinction of the dinosaurs and many other things occurs on page 893/916 where Frodo and Sam are lost in the mountain border of Mordor (The Return of the King –The Land of Shadow).

“The tops of the Morgai were grassless, bare, jagged, barren as a slate.”

The Primate lineage that becomes the Hominids, our ancestors, evolves on page 906/916. Frodo and Sam, starving and thirsty, approach Mount Doom through the surrounding wasteland (The Return of the King – Mount Doom).

“Then let me carry it a bit for you.”

Finally, on page 916 we come to the last 5 million year. Frodo and Sam are slumped on the slope of an erupting Mount Doom after destroying the ring (The Return of the King –Mount Doom). All of human history fits into the last sentence

“Here at the end of all things, Sam.”

So is this effective? I guess one needs to know the story to get the full effect but even just looking at the page numbers will give you the right idea. Most of the interesting stuff happens in the last few pages. Almost nothing much happens in the first two thirds. Life, itself, arrives surprisingly early.

I feel like it helps me with to work with the notion of lots of time.

“It’s only forever, not long at all”

sings David Bowie in the song Underground in the Movie Labyrinth. The more I think about it, the more I think that this is a very perceptive line.

Still, I am out of time for now. I’m off to celebrate my granddaughter’s birthday.

The author, Adrian Paterson, is a lecturer in the Department of Pest-management and Conservation at Te Whare Wānaka o Aoraki Lincoln University. He has experienced a lot of time.

February 16, 2026