EcoLincNZ

Category: Tolkien

  • 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

  • Induced resistance, Sting, and the blades of Westernesse

    It’s a big, bad world out there and it is nice to find something that adds to our protection.This can range from vaccines against viruses, to seatbelts in cars, to laws against causing physical harm. As a naked ape we are not especially intimidating on our own and we often seek out tools to make us safer.

    “With both hands he held the elven-blade point upwards …; and so Shelob, with the driving force of her own cruel will, with strength greater than any warrior’s hand, thrust herself upon a bitter spike. Deep, deep it pricked, as Sam was crushed slowly to the ground.
    No such anguish had Shelob ever known, or dreamed of knowing, in all her long world of wickedness. Not the doughtiest soldier of old Gondor, nor the most savage Orc entrapped, had ever thus endured her, or set blade to her beloved flesh.” Lord of the Rings, JRR Tolkien (Image by Tony Galuidi; main image by Alan Lee)

    One of the key points of “The Lord of the Rings” (and all of Tolkien’s writing) is that small, seemingly ineffectual, individuals can make a real difference in the world. It’s not by chance that hobbits are smaller than humans, weaker than dwarves, less knowledgeable than elves. Tolkien emphasised their ‘normality’.

    Hobbits do have their strengths though, especially in resilience. They are able to withstand the corruption of the ring far longer than other races. Boromir, a doughty man, only has to see the ring once before plotting to ‘borrow it’ for helping with his people. Both Bilbo and Sam, ordinary hobbits, are both able to wear the ring and give it up freely, which no others have done.

    Still, even Tolkien realised that the hobbits needed a little bit of an assist, something that would help to bring out their resilient traits. Tolkien chose to give each hobbit a long dagger with an ancient pedigree. Sting was found by Bilbo. It was a blade that shone with a faint light when evil was near. Sting was made long ago in the first age by elves of Gondolin. Tom Bombadil rescues the hobbits from a barrow wight and gives them each a dagger of Westernesse. These were made a couple of thousand years before in the early Third Age by men of the Dunedain Northern kingdom.

    Each of these blades become crucial to the hobbits achieving beyond their expectations. Pippin stabs a troll chief, who are largely immune to most weapons, and makes a difference at the Battle of the Moranon. Merry cuts the Witch King’s sinews allowing Eowyn to destroy the head Nazgûl in the Battle of the Pelennor Fields, when no one else can touch him. Sam uses Sting to wound Shelob and scare her off, when nothing else would work.

    Importantly, the blades were built with different foes in mind. The blades of Westernesse were built to fight the Witch King and his minions but are useless against giant spiders. Sting was built at a time when Ungoliant’s spider brood were numerous and roaming the world, and so it is effective against Shelob and her webs.

    Merry stabs the Witch King and breaks the spell allowing Eowyn to destroy him.
    “No other blade, not though mightier hands had wielded it, would have dealt that foe a wound so bitter, cleaving the undead flesh, breaking the spell that knit his unseen sinews to his will.” – Lord of the Rings, JRR Tolkien

    So, the hobbits left the Shire with their natural hardiness and common sense, but were primed with blades to make themselves more resilient to the difficult situations that they were to face.

    There is a similar concept when it comes to immune systems. Most plants and animals have evolved sophisticated immune systems that respond to pathogens in the surrounding environment. Having a complex immune response is especially important in dense populations where disease and parasites can quickly spread. One such situation is with crop species.

    Crops, where individuals from one species are packed tightly together, are targets for various pest species that can infect an individual and easily move to the next. For the last 100 years or so we have had the luxury of applying chemicals to help keep the plants healthy by reducing pathogens. This is no longer an an attractive option as it once was as pathogens have become resistant and people have become less tolerant of nasty chemicals in their landscapes and food sources.

    One solution is to create induced resistance through biological and chemical inducers. These inducers can artificially trigger immune defences and enhance their responses. For example, grape crops can suffer from downy mildew. Chitosan, a sugar obtained from the shell of crabs, can be sprayed on vines, triggering immune responses that can reduce downy mildew by 90%, compared to what would happen if grapes responded ‘normally’!

    “His little sword was something new in the way of stings for them. How it darted to and fro! It shone with delight as he stabbed at them.” The Hobbit, JRR Tolkien (Image by J. Catlin)

    Just like the blades of Westernesse helped the hobbits, these inducers allow the individuals to respond faster, more intensely, and achieve more than they would otherwise be able to do. Some inducers are useful for a variety of pathogens in many crops, such as Acibenzolar-S-methyl (ASM), and some are very specific, such as Saccharomyces yeast extract.

    Helen Rees, Lincoln University, and colleagues from Plant and Food, University of Auckland, and Scotland’s Rural College have put together a review in the journal Phytopathology about where the field of induced resistance in crop species stands. They look at what has worked on particular crops and the future roles and opportunities for inducers. They conclude that it is an exciting time for this field and that future crop protection may revolve around the next generation of inducers, playing a pivotal role in moving to a reduced pesticide future.

    While inducers may not have the glamour of a Bilbo using Sting to free dwarves from giant spider webs in Mirkwood, they have world-wide contributions to make to feeding a hungry planet by countering the ravening hordes of crop pathogens. Cutting edge indeed!

    Adrian Paterson is a lecturer in Pest-Management and Conservation at Lincoln University. He likes Sting (both in the Lord of the Rings and in The Police).

  • The legacy of Smaug: Exotic worms conquer New Zealand’s soils

    My armour is like tenfold shields, my teeth are swords, my claws spears, the shock of my tail is a thunderbolt, my wings a hurricane, and my breath death!” Smaug from The Hobbit, by JRR Tolkien.

    Wyrms or worms? It’s probably not the introduction you’d expect from your typical friendly neighbourhood earthworm, but as it turns out, they’re not as harmless as they may seem. Could it be that introduced specimens are actually taking over the home-soils of worms native to Aotearoa New Zealand?

    I am king under the mountain!
    Image by whadatobexy (CC)

    An invasion as ruthless as that of Smaug (you know, the “specially greedy, strong and wicked worm” described in JRR Tolkiens “The Hobbit”), when he drives the dwarves from their tunnels beneath the Lonely Mountain? Well, maybe.

    New Zealand is actually one of the countries with the highest number of endemic earthworms (“endemic” meaning they exist nowhere else in the world). It has over 200 different species, all of them in the Megascolescidae family.

    They thrive in soils of native vegetation but rarely survive in land used for agricultural purposes. For this reason, it’s fair to assume that the land-use-change, caused first by the Māori, then the Europeans, was not appreciated by the worms living in that ground. With the introduction of agriculture and pastures, it didn’t take long for native earthworms to disappear, only hanging on in areas that were still covered with the original vegetation.

    Twenty-three species of European earthworms (from the Lumbricidae family) were introduced. They quickly took over the changed habitats and ecological functions from their New Zealand worm-cousins, which themselves continued to live in exile, deep within the realms of untouched soils (this, and further information can be found here).

    Can we mingle?
    Image by Petr Kratochvil (CC0)

    As described here, European species have been moving from agricultural land into adjacent native vegetation. We know from other parts of the world, like the US, that the presence of invading exotic earthworms causes changes in the soil, such as nutrient levels. This has effects on the entire ecosystem as well as on the native worms living there.

    One of the first studies to look at the co-existence of the exotic and native earthworm species in New Zealand was done by researchers from Lincoln University in 2016. The study was called “Response of endemic and exotic earthworm communities to ecological restoration“. The goal of the project was to find out if endemic earthworm species would come back to recolonise areas where native vegetation has been restored. The study looked at  two sites, located on the east and on the west coasts of New Zealand’s South Island. On one of them, plant restoration had been happening for over 30 years, on the other for 8 years.

    The team of researchers excavated soil from each site and hand-sorted out all worms present. In the lab, they were carefully identified as either endemic or exotic. After the slimy work was done, the following conclusion was reached: the populations of endemic worms increases alongside the length of the restoration period. In the meantime, the population of exotics remained more or less stable.

    In restored sites exotic and endemic earthworms can co-exist in native soil. However, exotics may make life more difficult for New Zealand’s endemic worms, perhaps by making the soil less favourable for them, or just eating up the yummy leaf-debris. Further studies are urgently needed! However, despite these negative implications, are exotic earthworms just another invasive species in New Zealand, something we should get rid of to save the natives?

    Care for a handful?
    Image by Sippakorn Yamkasikorn (CC)

    The endemic worms are definitely not as feisty as JRR Tolkiens dwarves (I imagine them perhaps with more of a sedate and gentle character, more hobbit-like really, lots of second breakfasts and idling around the Shire). They most likely aren’t planning a revolt to reconquer their homeland that has been turned into pastures and cropland.

    Today, agriculture plays an immense role in New Zealand, and the European worms have become indispensable to the farmland areas, as as they provide many benefits in terms of waste recycling, soil fertility and crop productivity. This has encouraged efforts to continue increasing the dispersion of exotic earthworms in New Zealand’s agricultural land in recent years. It seems the exotic worms, like Smaug, are already hoarding the “gold” of the New Zealand’s fertile lowland agricultural soils and have begun expanding their sovereignty into the depths of the native land.

    Our native worms may need their own King Under the Mountain to come and save the day!

    This article was prepared by international exchange postgraduate student Nicola Wegmayr as part of the ECOL608 Research Methods in Ecology course.

    The study this blog is based on can be read here. It is the source of most of the factual knowledge that has been included.

    Boyer, S., Kim, Y.-N., Bowie, M., Lefort, M.-C., and Dickinson, N. (2016). Response of endemic and exotic earthworm communities to ecological restoration. Restoration Ecology, 24(6):717-721. https://dx.doi.org/10.1111/rec.12416

  • I see you: Sauron and the panda

    “I wish we could get away from these hills! I hate them. I feel all naked on the east side, stuck up here with nothing but the dead flats between me and that Shadow yonder. There’s an Eye in it. Come on! We’ve got to get down today somehow.” JRR Tolkien, The Lord of the Rings

    We’ve all had that feeling of being watched, of something that has taken an interest in what we are doing, and not perhaps with our best interests. It makes us fell uncomfortable, awkward, and we often change our behaviour in response, become more cautious, less spontaneous.

    Tolkien knew the power of the watching individual. Sauron, the chief antagonist in The Lord of the Rings, is literally portrayed as the Great Eye – “The Eye was rimmed with fire, but was itself glazed, yellow as a cat’s, watchful and intent, and the black slit of its pupil opened on a pit, a window into nothing. Then the Eye began to rove, searching this way and that; and Frodo knew with certainty and horror that among the many things that it sought he himself was one.” Knowing that someone can see you wherever you are is about as big a threat as we can imagine, whether it is Sauron, your boss, or your mother! We generally hate the concept that someone is watching us.

    Tolkien loved the word ‘watch’ (he used it over 330 times in the Lord of the Rings!). The watch-tower of Weathertop is the site of Frodo’s wounding, a Watcher-in-the-water nearly ends the journey at the entrance to Moria, there are Silent Watchers at the gates of Cirith Ungol, the menace of the Old Forest, Fangorn (known as the Watchwood to the Ents). Threats are usually described in the language around the feeling of being watched. And it works, it quickens the pulse of the reader. We know the feeling and respond.

    Ever get that feeling that something was looking for you?

    The problem with knowing that you are observed (or can be observed) is that you behave in ways that are different to your normal behaviour. Many species will respond to observation by not performing rarer sorts of behaviour, like play or reproduction, or by moving away from the observer.

    Gollum knows all about the watching eye and this makes him much more cautious in his movements. “His Eye watches that way all the time. It caught Smeagol there, long ago.’ Gollum shuddered. ‘But Smeagol has used his eyes since then, yes, yes: I’ve used eyes and feet and nose since then. I know other ways. More difficult, not so quick; but better, if we don’t want Him to see. Follow Smeagol! He can take you through the marshes, through the mists, nice thick mists. Follow Smeagol very carefully, and you may go a long way, quite a long way, before He catches you, yes perhaps.’ Gollum scuttles about because he does not want to be observed.

    Frodo, under the wearying influence of the ring as he stumbles through Mordor, almost completely changes his normal behaviour under the threat of constant detection. “Anxiously Sam had noted how his master’s left hand would often be raised as if to ward off a blow, or to screen his shrinking eyes from a dreadful Eye that sought to look in them. And sometimes his right hand would creep to his breast, clutching, and then slowly, as the will recovered mastery, it would be withdrawn.” If not for Sam, who does not have this anxiety, Frodo would not make it to Mt Doom.

    In animal behaviour we have a similar problem. We usually want to observe an animal’s ‘normal’ behaviour but they will often change their behaviour if they can see a human watching them. Today, technology can come to our aid.

    Yes, yes we realise you are the cutest species… Red Panda resting. Image from Kat Bugler.

    One of the more powerful new-ish tools available to those that study animal behaviour are trail cameras. These devices allow us to observe animals in the field 24/7 (just as long as they wander past the unsleeping gaze of the lens and trigger the image capture). This is a huge improvement for behavioural studies, as we can watch without the actual presence of human observers. We have used cameras in many studies here at Lincoln, mostly in understanding the life history and behaviour of nocturnal mammalian pest species..

    Recently, we used trail cameras to find out more about red panda in Nepal. Cameras were placed on red panda latrine trees (which are exactly what you are imagining). We were able to record activity patterns of wild red panda in their natural environment. Such data is useful in working out management plans to help with their conservation. We were also able to record other wild species that share their habitat.

    In some of these captured images, it appeared that the red pandas were looking at the trail cameras. If they are aware of the cameras then this might alter their behaviour. Maybe they are curious and spend more time loitering in the areas? Maybe they are frightened and don’t behave in their normal way?

    Kat Bugler, as part of her MSc at Lincoln University (with supervisors Adrian Paterson and James Ross), decided to examine whether red pandas were camera shy. Kat was able to get permission from zoos in New Zealand and Australia to observe their captive red panda in their enclosures. Each habitat was different but Kat was able to set up trail cameras to record behaviour around the main activity areas and platforms. She had a more powerful camera set up out of the enclosure to record behaviour of the pandas in these areas and around the trail cameras. Kat also spent time recording her own observations.

    Trail camera setup in a zoo enclosure. Image from Kat Bugler.

    In a paper published in Animals, Kat was able to show that there was a difference in red panda behaviour when a human observer was watching them, compared to a camera. When red panda were being watched by an individual they defecated less, ate less, moved less, played less, rested less, and slept more than when they were only being ‘watched’ by the trail cameras. Red panda were much slower to change behaviours when being observed. Interestingly, there were similar differences, if not as large, when comparing behaviour recorded by the outside camera compared to the enclosure trail cameras. The presence of people changes red panda behaviour, but so does the presence of a trail camera.

    These are subtle changes. Trail cameras are hardly the eye of Sauron: “And suddenly he felt the Eye. There was an eye in the Dark Tower that did not sleep. He knew that it had become aware of his gaze. A fierce eager will was there. It leaped towards him; almost like a finger he felt it, searching for him.” Are trail cameras useful for monitoring red panda behaviour if they can cause changes in behaviour? Absolutely, they do record all of the behaviour that red pandas exhibit, they just may alter the duration and frequency of occurrence. As long as we bear that in mind then we have a great tool to use in the wilds of the Himalayas and in understanding more about the red panda.

    “He did not feel invisible at all, but horribly and uniquely visible; and he knew that somewhere an Eye was searching for him” Maybe Sauron would have been better off putting trail cameras on all of the paths into Mordor!

  • The big, bold, redbacks of Buckland

    “No, Mr Baggins has gone away. Went this morning, and my Sam went with him: anyway, all his stuff went. Yes, sold out and gone, I teller. Why? Why’s none of my business, or yours. Where to? That ain’t no secret. He’s moved to Bucklebury or some such place, way done yonder. Yes it is – a tidy way. I’ve never been so far myself; they’re queer folks in Buckland. No, I can’t give no message. Good night to you!” JRR Tolkien – The Fellowship of the Ring

    One of the greatest illustrations of Tolkien’s work, IMHO, The Gaffer and the Black Rider by Stephen Hickman.

    I’ve always liked this passage where old Gaffer Gamgee is talking, unbeknown, to a nazghul. It is an important story point but delivered in the type of conversation that you could hear all over the world. ‘Those people that live 20 – 30 km away are just so different and weird!‘ Are the people of Buckland really so different to the good, honest folk of the Shire? If so, how did this happen by simply crossing a river?

    There is a question around invasive species whether the individuals that arrive in a new area are just a random selection of the individuals (and their traits) that live in their home area or whether they represent a group of individuals with consistent and particular traits that make them more likely to have successfully invaded the new area.

    For example, all humans in Aotearoa/New Zealand have arrived from outside these shores over the last 1000 years. Were the people that made their way here more bold and explorative than the rest who stayed behind? Or were they no different than their neighbours who stayed at home? Maybe they just simply had the opportunity to go?

    These ideas are important in thinking about why invasive species are successful at establishing or not. If any old random subset of the population can turn up then they are less often going to successful at establishing (they may not be fit-for-purpose!) compared to if they arrive with skills that allow them to survive better in a new environment (or even to survive the journey).

    Being large might help give invasive individuals an advantage over native species. Likewise, producing more offspring, growing faster, being bold, exploring more, dispersing sooner, having a broader diet, could all help with invading and establishing.

    What about our Bucklanders?

    “Long ago Gorhendad Oldbuck, head of the Oldbuck family, one of the oldest in the Marish or indeed in the Shire [has had high evolutionary fitness over many generations], had crossed the river [successfully able to disperse relative to other hobbits and to explore more], which was the original boundary of the land eastwards. He built (and excavated) Brandy Hall, changed his name to Brandybuck, and settled down to become master of what was virtually a small independent country. His family grew and grew [high fecundity in offspring production], and after his days, continued to grow, until Brandy Hall occupied the whole of the low hill, and had three large front-doors, many side-doors, and about a hundred windows. The Brandybucks and their numerous dependants then began to burrow, and later to build, all round about … The people in the Marish were friendly with the Bucklanders … But most of the folk of the old Shire regarded the Bucklanders as peculiar, half foreigners as it were [suggests a slightly different distribution of traits compared to the parent population].Though, as a matter of fact, they were not very different from the other hobbits of the Four Farthings. Except in one point: they were fond of boats, and some of them could swim [bold and innovative behaviours].” JRR Tolkien- The Fellowship of the Ring

    Captive redback with web. Image by Adrian Paterson.

    We are also told elsewhere that the Brandybucks and Tooks (another bold lineage of hobbits) are generally taller than average Shire hobbits. Tolkien, as I have said in many other places (taxonomy of orcs and hobbits, evolutionary biology ideas, burrow architecture, mammal pest management, fire and ecosystems), was rather accurate when it came to integrating biology into his writing. Did he get it right here?

    To test this invasion idea you need a species that is well-studied in it’s native range as well as in its colonising range. You also need to be able to measure all of those traits. Spiders fit the bill nicely. They’re small and have short generations, are easy to fit into small experimental set ups, and some are venomous and, therefore, well studied. Enter the redback spider (Latrodectus hasselti), invasive in Japan and New Zealand and well studied in its Australian homeland.

    Cor Vink, New Zealand’s leading arachnologist, joined a group based in Toronto, Canada headed by Monica Mowery, to look at individuals from these three areas. They measured the size of individuals (bigger is usually better in interactions with competitors), their egg sac production (producing more young may give you more opportunities for at least some surviving), and length of generation times in captive populations (shorter allows for faster replacement, longer allows for larger more long-lived individuals).

    A redback – amazing photo from the talented Bryce McQuillan

    They measured the behaviour of the redbacks, such as frequency of cannibalism (you never know when a snack might come in handy!). Also, individual spiders were placed in a new environment and the speeds at which they started spinning webs (exploration) or moving after being exposed to a puff of wind (boldness) were measured. Spiders were also placed into a warm arena with a small simulated breeze to see whether they would balloon (effectively float away in the wind) or rappel (climb using their web silk) away from the start point (dispersal).

    The outcomes from this work were published in Biological Invasions. Redbacks from the invasive populations showed more dispersal behaviour than the home populations. They also tended to be larger in size, more cannibalistic, and produced more offspring. Interestingly, the redbacks in Japan and New Zealand did not seem to be more bold or explorative than in Aussie. Overall though, the invasive populations looked and acted differently to the source population.

    It appears that populations that successfully disperse and establish in new areas might do so because they are settled by individuals with useful traits that differ a little from the source population. This may help us to figure out which species potentially pose the most invasive threats.

    What about those strange Bucklanders? The Gaffer was mostly right. They are a bit different. Bucklanders are a population that managed to successfully disperse to an isolated area. Bucklanders are larger and more fecund. Tolkien does not record whether the Bucklanders tended to be more cannibalistic than hobbits in the Shire, but that would be a prediction!

    We can certainly sympathise with the Gaffer’s concerns about his Sam going to live among them.