Kingdom of Plants – Life in the Wet Zone


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A sharing economy for plants: Seed libraries are sprouting up



File 20181116 194516 3q61w9.jpg?ixlib=rb 1.1
Got a license for those seeds?
xuanhuongho/Shutterstock.com

Michael Carolan, Colorado State University

Thanksgiving may be uniquely American, but its core spirit was exported from harvest festivals stretching back for millennia. Its essence is being grateful for what one has, while noting a duty to share one’s good fortune.

In my new book, “The Food Sharing Revolution: How Start-Ups, Pop-Ups, and Co-Ops are Changing the Way We Eat,” I look at sharing from a variety of angles – good, bad and downright ugly. One example is the custom of seed sharing, which can be traced from indigenous societies and the earliest fall festivals that ultimately inspired American Thanksgiving.

For centuries, people in agrarian societies shared seeds to help each other subsist from year to year. Today, thanks to intellectual property rights and often well-intentioned laws, our ability to share seeds is restricted. Realizing this, food activists, garden enthusiasts and community leaders are trying to make it easier by making seeds available through libraries. Surely there’s nothing controversial about that, right? Actually, there is.

Seed swap at the ‘Harvesting Change: Food and Community’ gathering in Detroit, Michigan, May 20, 2014.
W.K. Kellogg Foundation, CC BY-ND

Free seeds by mail

Until the early 1800s, U.S. farmers either saved seed from their own crops or obtained it through personal networks. Then in 1819, Treasury Secretary William Crawford called upon all ambassadors and military officers stationed overseas to collect seeds and bring them home, where they would be shared freely.

Seed advertising card, 1887.
Boston Public Library, CC BY

Initially this program was informal, but in 1839 Commissioner of Patents Henry Ellsworth persuaded Congress to appropriate funds for it. Ellsworth owned large tracts of land in the Midwest, so his motives may not have been strictly public-minded. Soon his office was distributing 60,000 seed packages annually through the U.S. mail. By the turn of the 20th century, the Department of Agriculture was shipping a billion free packages of seed each year.

This was relatively uncontroversial until 1883, when a group of representatives from mostly vegetable seed trade firms formed the American Seed Trade Association. No business model can work if the government gives away for free what private merchants want to sell.

After decades of lobbying, the group convinced Congress to end the free seed program in 1924. Without granting ownership rights to plant breeders, members argued, there would be no incentive to “improve” seed for qualities such as yield, tolerance, germination length, root depth or aesthetics. As two plant breeders put it in 1919:

“The man who originates a new plant which may be of incalculable benefit to the whole country gets nothing – not even fame – for his pains, as the plants can be propagated by anyone.”

The 1930 Plant Patent Act was a watershed. It initially applied only to nursery plants propagated through cuttings, such as roses and apple trees. Soon, however, breeders of agricultural commodities pressed to expand the law in recognition of their labor. As a result, the majority of commercial crops and garden plants in use today were developed by agricultural companies, to the point that three companies – Bayer Monsanto, DuPont and Syngenta – account for roughly 50 percent of all global seed sales.

Today the seed industry is highly controlled. Every state has laws that require suppliers to obtain licenses, test seeds to ensure they are the variety advertised and properly label them. And the federal government regulates seed sales across state lines.

These laws exist for good reason. If farmers buy seed that turns out to be the wrong variety, or doesn’t germinate, their livelihood is at risk. Seed laws hold providers accountable and protect buyers. Some laws apply even to those who offer seeds for barter, exchange or trade.

Benton County Nursery Co. seed catalogue, 1960.
Internet Archive Book Images

Seed sharing redux: Seed libraries

But another community pillar is distributing seeds without charge: Libraries. The process works much the same as with books. Patrons receive seeds and plant them, then allow some of their plants to go to seed and return those seeds to the library for others’ use.

According to some proponents, there are more than 660 seed libraries in 48 states. Public libraries, universities and secondary schools are getting involved. Their motives range from preserving plant diversity and local history to enhancing food access and building regional agricultural resiliency in the face of climate change.

One of the nation’s first seed libraries is the Bay Area Seed Interchange Library, or BASIL, which opened in 2000 at the Berkeley Ecology Center in Berkeley, California and is run by volunteers. Sascha DuBrul, its founder, is said to have came up with the idea after wanting to find a home for seeds that were left when the University of California, Berkeley closed its campus farm.

A librarian from the Tulsa City and County Community Library in Oklahoma explains their seed program.

People who I interviewed for my research say the seed library movement has grown exponentially, starting with a few pioneers but expanding rapidly in the past five years. The movement includes food and community activists, gardeners, lawyers and citizens who support the idea that everyone has a right to seed.

Libraries don’t test seeds or place expiration dates on packaged seed, so some states have moved to regulate seed libraries. For example, in 2014 the Pennsylvania Department of Agriculture informed the Joseph T. Simpson Public Library in Mechanicsburg that it was violating the state’s Seed Act of 2004 and needed to follow the same stringent requirements as agricultural supply companies.

Labels had to be in English and clearly state the plant’s species name or commonly accepted name, and the library had to conduct germination and purity analyses. Failure to do so, one county commissioner asserted, could threaten local food supplies through what she called “agri-terrorism.”

The seed library eventually reopened after officials
agreed that patrons would not be required to bring seed back to the
library, and that seeds it provided would be commercially packaged. It now hosts seed swap events to encourage person-to-person sharing.

Defending the right to share

Seed sharing advocates believe, as one who I will call Barry told me, that “people ought to be able share seeds without being treated like they’re Monsanto.” Many are alarmed by government crackdowns on seed libraries.

I met Barry in Lincoln, Nebraska, where he was advising state officials on adding an exemption to the state’s seed law for seed libraries. “I’ve made the rounds”, he confessed when asked how many states’ revised seed laws have his fingerprints on them.

Since 2015, states ranging from Minnesota to Nebraska, Illinois and, more recently, Alaska have adopted such exemptions. In North Carolina, seed libraries are legal thanks to a blanket seed sharing exemption that applies to all nonprofit oganizations. Alabama exempts any providers who sell up to US$3,000 worth of seed.

In September 2016, California Governor Jerry Brown signed Assembly Bill 1810, known among activists as the Seed Exchange Democracy Act, into law. The measure amended state law to exempt seed libraries from burdensome testing and labeling requirements.

Despite these successes, a number of activists I spoke with fear that agribusinesses seeking to protect their intellectual property rights will push back if the seed library movement keeps expanding. The hard reality is that sharing is not a right, even in this age of the so-called sharing economy, if the thing people want to share is a valuable commodity.The Conversation

Michael Carolan, Professor of Sociology and Associate Dean for Research & Graduate Affairs, College of Liberal Arts, Colorado State University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Figs, ferns and featherwoods: learn all about Australia’s native trees and plants


File 20180810 30458 7p3gcy.jpg?ixlib=rb 1.1
You love Australian plants, I love Australian plants, we all love Australian plants!
Percita/Flickr

Madeleine De Gabriele, The Conversation and Molly Glassey, The Conversation

Sign up to the special Beating Around the Bush newsletter here.


Australia is classified as “megadiverse” meaning it’s a global hotspot for plant and animal diversity, and has vast numbers of unique species found nowhere else on Earth. With this newsletter we want you to be able to wander down the garden path, off the beaten track, and smell the gum leaves. Specifically, what kind of gum leaf? What is it from? Where does it grow?




Read more:
Bunya pines are ancient, delicious and possibly deadly


We’ll let you know every time a new edition in our Beating Around the Bush series comes out, putting the spotlight on a different native plant every time. We’re on a roughly fortnightly schedule, but like any garden there might be a few surprises along the way. I’ll also be rounding up some of the greatest hits from our archives, and talking about what’s new in the plant world.

This one is for all you floraphiles out there.
Felicity Burke/The Conversation

The ConversationIf someone else in your life might enjoy this mix in their inbox, please let them know about it. And if you have any feedback, feel free to let us know in the comments.

Madeleine De Gabriele, Deputy Editor: Energy + Environment, The Conversation and Molly Glassey, Audience Development Manager, The Conversation

This article was originally published on The Conversation. Read the original article.

Polar invasion: how plants and animals would colonise an ice-free Antarctica



Image 20150914 4680 8vs2vt.jpg?ixlib=rb 1.1

Tom Hart, Author provided

Peter Convey, British Antarctic Survey and Tom Hart, University of Oxford

Antarctica’s ice sheets could totally collapse if the world’s fossil fuels are burnt off, according to a recent climate change simulation. While we are unlikely to see such a dramatic event any time soon, we are already observing big changes and it’s worth considering what the worst case scenario might look like for the continent’s ecosystems. How long before Antarctica turns into grassy tundra?

For now, life thrives mostly at the very edge of the continent – it’s driven by the plankton-rich Southern Ocean and clustered around seasonally ice-free areas of coastal land. The interior might be sparsely inhabited, but the continent is not as barren as many think. There are around 110 native species of moss and two flowering plants, the Antarctic hairgrass and pearlwort. These plants have flourished along the relatively mild Antarctic Peninsula in recent decades. However they can’t go much further – they already occur at almost the most southern suitable ice-free ground.

With ice-caps and glaciers receding already in the Peninsula region, native land plants and animals are benefiting from more easily available liquid water. Already we are starting to see increased populations, greater areas occupied and faster growth rates, consequences only expected to increase – everything is currently limited by the extreme physical environment.

The world’s most southerly flower, the Antarctic hairgrass (Deschampsia Antarctica)
British Antarctic Survey, Author provided

It may eventually prove too warm for some native species, but the bigger issue in upcoming decades and centuries will be whether new and currently “non-native” species will arrive that are stronger competitors than the native organisms.

Antarctic invasions

Native polar species are inherently weak competitors, as they have evolved in an environment where surviving the cold, dry conditions is the overriding selective pressure rather than competition from other biological sources. If humans (or other wildlife expanding their range southwards) bring new competitors and diseases to Antarctica, that may pose a very grave risk to the existing biodiversity. Some native species would likely be pushed into the remaining more extreme regions where they can avoid competition and continue to rely on their inherent stress tolerance abilities.

Tom Hart with two million chinstrap penguins. Isolation has made Antarctic species vulnerable to introduced competition.
Richard White, Author provided

We usually split the process of natural colonisation – which applies even today in Antarctica – and that of movement of “alien” species by human agency. The best available data for the Antarctic region come from some sub-Antarctic islands, where it appears humans have been responsible for many more successful colonisations than nature. In fact, over the recent centuries of human contact with the region we have introduced 200-300 species compared to just two or three known natural colonisations.

Penguins, seals and flying seabirds move between islands and the Antarctic Peninsula, so there is potential for some natural colonisation. Vagrant birds are regularly observed across the sub-Antarctic and even along the Peninsula, some of which have colonised successfully (such as the starlings, redpolls and mallard ducks on Macquarie Island).

Migrants such as skuas and gulls, which spend time on land at both ends of their migration, could be important natural vectors of transfer for invertebrates, plant seeds and spores, and microbes into an ice-free Antarctica. Importantly, bird colonies also fertilise surrounding rock and soil with faeces, eggshells and carcasses. Plant and animal life flourishes near seabird colonies, encouraged by this enrichment.

What’s hitching a ride on this skua?
Tom Hart, Author provided

However it can be tough to predict what Antarctic melt would mean for individual species, never mind entire ecosystems. Take penguins, for instance – they have already survived previous inter-glacial retreats, but at reduced population sizes. This time round it is likely that Adélie and emperor penguins who are more dependent upon sea ice would decline, while less ice-dependent species such as gentoos and chinstraps might benefit. Indeed, there is already some evidence that emperors are struggling (although also that they may be adapting and learning to emigrate).

However the fact fish-eating gentoo penguins are increasing on the Peninsula while Adélies and chinstraps (both krill eaters) aren’t doing so well suggests prey availability can be more to blame than ice cover. Figuring out the impact of large-scale environmental change at ecosystem or food-web level is hard – it’s a complex process that will no doubt throw up some unexpected results.

This flightless midge comes from South Georgia but has been introduced further south.
British Antarctic Survey, Author provided

The sub-Antarctic islands are full of examples of such unexpected impacts. Pigs, dogs, cats, sheep, reindeer and rabbits have all been intentionally introduced in the past, with often devastating effects. Rats and mice were introduced to South Georgia and other islands accidentally by sealers and whalers, for instance, and have decimated seabird populations. A recent eradication campaign appears to have been successful and pipits, ducks and small seabirds are showing some immediate signs of recovery.

The removal of non-native cats from Macquarie and Marion Islands has similarly helped native burrowing seabirds, although responses in such ecosystems can be far more complex and unpredictable – the removal of cats from Macquarie also led to increase in the introduced rabbit population, and considerably increased damage to sensitive native vegetation.

Antarctic biodiversity is far more complex than widely assumed, with up to 15 distinct biogeographic regions that have been evolutionarily isolated for many millions of years. Humans present the greatest threat, not only of introducing new species, but also of moving “native” species between regions within Antarctica. This could be even more damaging, as these native species would already be pre-adapted to polar life.

Visitors to Antarctica are subject to increasingly strict biosecurity measures but accidental introductions continue to occur, often through food shipments for scientists. Changes in sea and land ice affect access to new areas, so we can only expect plant and invertebrate invasions to increase unless biosecurity becomes more effective.

The ConversationWhile cost issues may be raised, it is worth remembering that prevention will always be better – and cheaper – than subsequent control and eradication, even if such action is possible.

Peter Convey, Terrestrial Ecologist, British Antarctic Survey and Tom Hart, Penguinologist, University of Oxford

This article was originally published on The Conversation. Read the original article.

Bunya pines are ancient, delicious and possibly deadly



File 20180522 51135 rg8xdp.png?ixlib=rb 1.1

Flickr/Tatters/The Conversation, CC BY-SA

Ian Wright, Western Sydney University

Welcome to the first edition of Beating Around the Bush, a series that profiles native plants: part gardening column, part dispatches from country, entirely Australian. Read more about the series here or get in touch to pitch a plant at batb@theconversation.edu.au.


The Bunya pine is a unique and majestic Australian tree – my favourite tree, in fact. Sometimes simply called Bunya or the Bunya Bunya, I love its pleasingly symmetrical dome shape.

But what I really love about it is that there are just so many bizarre and colourful stories about this tree – the more you learn, the more you find it fascinating. (That is, unless the tree has harmed you; they come with some hazard warnings.)




Read more:
Curious Kids: Where did trees come from?



CC BY-ND

Can you grow it?

Bunya pines (botanical name: Aracauria bidwilli) are living fossils. They come come from a fascinating family of flora, the Araucariaceae, which grew across the world in the Jurassic period. Many of its “cousins” are extinct. The remaining members of the family are spread across the former landmasses of Gondwana, particularly South America, New Zealand, Malaysia and New Caledonia, as well as Australia.

This family includes one of the most amazing botanical discoveries of the 20th century, the Wollemi pine (Wollemia nobilis).




Read more:
Where the old things are: Australia’s most ancient trees


Bunyas used to be much more widespread than they are now. Today they grow in the wild in only a few locations in southeast and north Queensland. One such area, the Bunya Mountains, is the remains of an old shield volcano – about 30 million years old, with peaks rising to more than 1,100 metres. The Bunya pines grow in fertile basalt soils in this cool and moist mountain environment.

If you want to grow a Bunya, I would suggest that you need a large garden. The tree needs fertile and well-drained soil, and regular watering in drier climates. A shaded position will also help – it can struggle in direct sunlight in its youth.

Bunyas also produce highly valued timber, which is used for musical instruments. It is particularly valued as “tonewood” for producing stringed instruments’ sound boards. Saw logs for Bunyas come from plantations only, as they are protected in their national park wild habitat.

Stand well back!

While many people love Bunya pines, this love affair comes with a health warning. They are best regarded with both distance and respect!

The trees are big and typically range from 20m to 50m in height. Their leaves have strings of very rigid and sharply pointed leaves. If you come into physical contact with its leaves or branches, you must wear protective clothes and carefully handle them to avoid pain or even cuts. As a child, the swinging branch of a Bunya made a formidable garden weapon.

But that is nothing compared to this tree’s ability to hit you on the head, possibly with serious consequences. When in season (generally December to March) they can produce dozens of massive cones weighing up to 10 kilograms. These can drop from up to 50m without warning.


TreeMappa 2.0/Flickr, CC BY

I first learned of this when a fellow university student in the 1980s scored an impressively large Bunya cone dent in the roof of his battleship-solid FB Holden ute. My university campus has beautiful gardens displaying dozens of massive Bunyas, but one was perhaps a bit close to the car park. My university friend was lucky not to get hit. Many people have not been so lucky and some have even been hospitalised.

Bunya pines are beautiful trees in large gardens and are a feature of parks around Australia, but their habit of “bombing” people and property causes considerable angst. Many local councils erect warning signs or rope off the danger zone during cone season. Others hire contractors to remove the cones to protect their residents (and perhaps limit their own legal liability). Sadly, some Bunya pines have been cut down to remove the risk.

Indigenous use

The cultural connection of the Bunya pine to Aboriginal Australians is very powerful. The Bunya Mountains in southeast Queensland used to host massive gatherings of Aboriginal groups.

People came to visit the Bunya pines and feasted on the nuts in their abundant cones. Some travelled from hundreds of kilometres away, and traditional hostilities were dropped to allow access. The seed in the Bunya cone is a delicious and nutritious food, a famous and celebrated example of Australian bush tucker.


TreeMappa 2.0/Flickr, CC BY

Today some trees remain marked with hand and foot holes that Aborigines made in the trunks of older Bunyas. The climbers must have been brave and agile to harvest the cones from such heights.

Sadly, the last of the Aboriginal Bunya festivals was held in about 1900, as European loggers came to the area for its many timber resources.

The ConversationBut even those European timber pioneers realised the significance of the Bunya Mountains area. The Bunya Mountains National Park was declared in 1908, creating Queensland’s second national park.

Ian Wright, Senior Lecturer in Environmental Science, Western Sydney University

This article was originally published on The Conversation. Read the original article.

Plants use advertising-like strategies to attract bees with colour and scent


File 20180411 540 1wj58ue.jpg?ixlib=rb 1.1
A honeybee (left), a scarab beetle (middle), and a fly (right) feeding on flowers of the white rock rose in a Mediterranean scrubland.
Aphrodite Kantsa., Author provided

Aphrodite Kantsa, University of the Aegean and Adrian Dyer, RMIT University

Watching plants and pollinators such as bees can teach us a lot about how complex networks work in nature.

There are thousands of species of bees around the world, and they all share a common visual system: their eyes are sensitive to ultraviolet, blue and green wavelengths of the light spectrum.

This ancient colour visual system predates the evolution of flowers, and so flowers from around the world have typically evolved colourful blooms that are easily seen by bees.

For example, flowers as perceived by ultraviolet-sensitive visual systems look completely different than what humans can see.

However, we know that flowers also produce a variety of complex, captivating scents. So in complex natural environments, what signal should best enable a bee to find flowers: colour or scent?

Our latest research uncovered a surprising outcome. It seems that rather that trying to out-compete each other in colour and scent for bee attention, flowers may work together to attract pollinators en masse. It’s the sort of approach that also works in the world of advertising.




Read more:
Want a better camera? Just copy bees and their extra light-sensing eyes


Daunting amount of field work

Classic thinking would suggest that flowers of a particular species should have reasonably unique flower signatures. It makes sense that this should promote the capacity of a bee to constantly find the same rewarding species of flower, promoting efficient transfer of pollen.

So a competition view of flower evolution for different flower species with the same colour – for example purple – would suggest that each flowering plant species should benefit from having different scents to enable pollinator constancy and flower fidelity. By the same logic, flowers with the same scents should have different colours so they’re easily distinguished.

To know for sure what happens requires a daunting amount of field work. The challenges include measuring flower colours using a spectrophotometer (a very sensitive instrument that detects subtle colour differences) and also capturing live flower scent emissions with special pumps and chemical traps.

A wild bee of the genus Anthophora upon making the decision to visit the flowers of purple viper’s bugloss, in a Mediterranean scrubland in Greece.
Aphrodite Kantsa.

At the same time, in order to record the actual pollinator “clientele” of the flowers, detailed recordings of visits are required. These data are then built into models for bee perception. Statistical analyses allow us to understand the complex interactions that are present in a real world evolved system.

Not what we thought

And what we found was unexpected. In two new papers, published in Nature Ecology & Evolution and in Nature Communications, we found the opposite to competition happens: flowers have evolved signals that work together to facilitate visits by bees.

So flowers of different, completely unrelated species might “smell like purple”, whilst red coloured species share another scent. This is not what is expected at all by competition, so why in a highly evolved classical signal receiver has this happened?

The data suggests that flowers do better by attracting more pollinators to a set of reliable signals, rather than trying to use unique signals to maximise individual species.

By having reliable multimodal signals that act in concert to allow for easy finding of rewarding flowers, even of different species, more pollinators must be facilitated to transfer pollen between flowers of the same species.




Read more:
Which square is bigger? Honeybees see visual illusions like humans do


Lessons for advertising

A lot of research on advertising and marketing is concerned with consumer behaviour: how we make choices. What drives our decision-making when foraging in a complex environment?

While a lot of modern marketing emphasises product differentiation and competition to promote sales, our new research suggests that nature can favour facilitation. It appears that by sharing desirable characteristics, a system can be more efficient.

This facilitation mechanism is sometimes favoured by industry bodies, for example Australian avocados and Australian honey. En masse promotion of the desirable characteristics of similar products can grow supporter base and build sales. Our research suggests evolution has favoured this solution, which may hold important lessons for other complex market based systems.

A successful colour–scent combination targeted at attracting bees can be adopted by several different plant species in the same community, implying that natural ecosystems can function as a “buyers markets”.




Read more:
Curious Kids: Do bees ever accidentally sting other bees?


We also know from research that flowers can evolve and change colours to suit the local pollinators. Colours can thus be changed by flowers if instead of bees pollinating flowers, flies, with different colour perception and preferences, dominate the community.

These findings can also prove useful for identifying those colour-scent combinations that are the most influential for the community. This way, the restoration of damaged or disrupted plant-pollinator communities can become better managed to be more efficient in the future.

The ConversationWhen next enjoying a walk in a blooming meadow, remember plants’ strategies. The colourful flowers and the mesmerising scents you experience may have evolved to cleverly allure the efficient pollinators of the region.

Aphrodite Kantsa, Postdoctoral Researcher, University of the Aegean and Adrian Dyer, Associate Professor, RMIT University

This article was originally published on The Conversation. Read the original article.

Polar invasion: how plants and animals would colonise an ice-free Antarctica



Image 20150914 4680 8vs2vt.jpg?ixlib=rb 1.1

Tom Hart, Author provided

Peter Convey, British Antarctic Survey and Tom Hart, University of Oxford

Antarctica’s ice sheets could totally collapse if the world’s fossil fuels are burnt off, according to a recent climate change simulation. While we are unlikely to see such a dramatic event any time soon, we are already observing big changes and it’s worth considering what the worst case scenario might look like for the continent’s ecosystems. How long before Antarctica turns into grassy tundra?

For now, life thrives mostly at the very edge of the continent – it’s driven by the plankton-rich Southern Ocean and clustered around seasonally ice-free areas of coastal land. The interior might be sparsely inhabited, but the continent is not as barren as many think. There are around 110 native species of moss and two flowering plants, the Antarctic hairgrass and pearlwort. These plants have flourished along the relatively mild Antarctic Peninsula in recent decades. However they can’t go much further – they already occur at almost the most southern suitable ice-free ground.

With ice-caps and glaciers receding already in the Peninsula region, native land plants and animals are benefiting from more easily available liquid water. Already we are starting to see increased populations, greater areas occupied and faster growth rates, consequences only expected to increase – everything is currently limited by the extreme physical environment.

The world’s most southerly flower, the Antarctic hairgrass (Deschampsia Antarctica)
British Antarctic Survey, Author provided

It may eventually prove too warm for some native species, but the bigger issue in upcoming decades and centuries will be whether new and currently “non-native” species will arrive that are stronger competitors than the native organisms.

Antarctic invasions

Native polar species are inherently weak competitors, as they have evolved in an environment where surviving the cold, dry conditions is the overriding selective pressure rather than competition from other biological sources. If humans (or other wildlife expanding their range southwards) bring new competitors and diseases to Antarctica, that may pose a very grave risk to the existing biodiversity. Some native species would likely be pushed into the remaining more extreme regions where they can avoid competition and continue to rely on their inherent stress tolerance abilities.

Tom Hart with two million chinstrap penguins. Isolation has made Antarctic species vulnerable to introduced competition.
Richard White, Author provided

We usually split the process of natural colonisation – which applies even today in Antarctica – and that of movement of “alien” species by human agency. The best available data for the Antarctic region come from some sub-Antarctic islands, where it appears humans have been responsible for many more successful colonisations than nature. In fact, over the recent centuries of human contact with the region we have introduced 200-300 species compared to just two or three known natural colonisations.

Penguins, seals and flying seabirds move between islands and the Antarctic Peninsula, so there is potential for some natural colonisation. Vagrant birds are regularly observed across the sub-Antarctic and even along the Peninsula, some of which have colonised successfully (such as the starlings, redpolls and mallard ducks on Macquarie Island).

Migrants such as skuas and gulls, which spend time on land at both ends of their migration, could be important natural vectors of transfer for invertebrates, plant seeds and spores, and microbes into an ice-free Antarctica. Importantly, bird colonies also fertilise surrounding rock and soil with faeces, eggshells and carcasses. Plant and animal life flourishes near seabird colonies, encouraged by this enrichment.

What’s hitching a ride on this skua?
Tom Hart, Author provided

However it can be tough to predict what Antarctic melt would mean for individual species, never mind entire ecosystems. Take penguins, for instance – they have already survived previous inter-glacial retreats, but at reduced population sizes. This time round it is likely that Adélie and emperor penguins who are more dependent upon sea ice would decline, while less ice-dependent species such as gentoos and chinstraps might benefit. Indeed, there is already some evidence that emperors are struggling (although also that they may be adapting and learning to emigrate).

However the fact fish-eating gentoo penguins are increasing on the Peninsula while Adélies and chinstraps (both krill eaters) aren’t doing so well suggests prey availability can be more to blame than ice cover. Figuring out the impact of large-scale environmental change at ecosystem or food-web level is hard – it’s a complex process that will no doubt throw up some unexpected results.

This flightless midge comes from South Georgia but has been introduced further south.
British Antarctic Survey, Author provided

The sub-Antarctic islands are full of examples of such unexpected impacts. Pigs, dogs, cats, sheep, reindeer and rabbits have all been intentionally introduced in the past, with often devastating effects. Rats and mice were introduced to South Georgia and other islands accidentally by sealers and whalers, for instance, and have decimated seabird populations. A recent eradication campaign appears to have been successful and pipits, ducks and small seabirds are showing some immediate signs of recovery.

The removal of non-native cats from Macquarie and Marion Islands has similarly helped native burrowing seabirds, although responses in such ecosystems can be far more complex and unpredictable – the removal of cats from Macquarie also led to increase in the introduced rabbit population, and considerably increased damage to sensitive native vegetation.

Antarctic biodiversity is far more complex than widely assumed, with up to 15 distinct biogeographic regions that have been evolutionarily isolated for many millions of years. Humans present the greatest threat, not only of introducing new species, but also of moving “native” species between regions within Antarctica. This could be even more damaging, as these native species would already be pre-adapted to polar life.

Visitors to Antarctica are subject to increasingly strict biosecurity measures but accidental introductions continue to occur, often through food shipments for scientists. Changes in sea and land ice affect access to new areas, so we can only expect plant and invertebrate invasions to increase unless biosecurity becomes more effective.

The ConversationWhile cost issues may be raised, it is worth remembering that prevention will always be better – and cheaper – than subsequent control and eradication, even if such action is possible.

Peter Convey, Terrestrial Ecologist, British Antarctic Survey and Tom Hart, Penguinologist, University of Oxford

This article was originally published on The Conversation. Read the original article.