The Water Fern Azolla filiculoides

I have not been able to find much on the internet about this little water fern so have had to look at it myself. The roots look like I expected them to but under higher magnification there appeared to be many little root hairs, but then each one looked like club shaped bristles covering the whole root, just like a bottle brush. I then looked at the roots of the duck weed Lemna minor
and found it strange that they should be the same even though they are not at all related. Maybe the rootlets are infected with a .The mycorrhiza would assist the plants in obtaining phosphorus and nitrogen from the water while they in turn benefit by obtaining energy from the plants.The design of these two species shows convergence,with both solving their problems the same way.

These two pictures show Azola filiculoides root at the top and duck weed at the bottom

On the surface of the water there is what looks like a of green smudge covering much of the pond. On examination under the microscope I was horrified to fine that is made up of tiny new plantlets of duck weed exactly like the adults but really minute. About the size of a pin prick. I was unable to photograph them as the camera would no focus.

Invasive plants gain an advantage by being able to reproduce rapidly, vegetatively and sexually. Sexual reproduction would would make for variety and those lines most adapted would produce vegetatively faster than their rivals.




Bottom picture shows small bunches of new plantlets next to of duck weed parent plants more on duckweed and water fern association
After a few weeks of the pond being almost clear the Azolla has completely covered it. The few green patches are the duck weed. The azolla is so thick that after the rain water can be seen as small pools on the surface.

An interesting fact is that Azola is used as a fertilizer in rice paddies. Work is being done on its use in South Africa.

The Duckweed Azolla Assocoation










Kingdom: Plantae
Division: Pteridophyta
Class: Pteridopsida
Order: Marsileales
Family: Azollaceae
Genus: Azolla
Species: A.filiconoides








Kingdom: Plantae
Division:Magnoliophyta
Class: Liliopsida
Order: Alismatales
Family: Araceae
Genus: Lemna
Spcies: L.minor

The Azola water fern and duck weed Lemna minor are in no way related as can be seen above. L. minor is related to the arum lilly and the water fern to the tree fern so how far apart could they be.However they have both solved their problems the same way and often live in close association, so much so that they both seem to share the same species of mycorrhiza. It appears to be an Ectomycorrhiza association with a mantel hypha sheath, a Hartig net and external hypha.I have not been able to discover any reference to the micorrhiza in any of the numerous descriptions of duck weed on the internet.None of the drawings or photos of roots show mycorrhiza.

Micorrhizas perform the task of making phosphate available to plants but it has been discovered that in fact in L. minor the roots
do not take up nutrients at all. Roots are for keeping the plant upright in the water, and by entwining with other roots as the top photo shows and keep the plants together to form a mat on the surface of the water.The nutrients are taken in through the bottom side of the leaflets. Whether this holds for the water fern as well I do not know.

L.minor is very widespread through many countries and is very invasive but not necessarily always a problem.

Another curious thing is that there are structures attached to the roots like long root hairs,these are shown in the bottom photo. The photo of the glass container is of Azolla and duckweed growing together

More thoughts on Erosion

I have found more pictures I took after the floods of 2004One shows even more damage than I saw in the others.It was taken with the telephoto

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This picture shows the subsoil which is like marble size balls. When they become wet they are very greasy and slippery and during excessive rainfall they simply roll down the slope taking the top soil and grass with them..

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This pic shows the root system of two African grasses, on the left and far right, Eragrostis curvula and centre Themeda triandra, root development is down two feet showing the tremedous ability to hold the soil together. The roots are very tough and fibrous.

This picture shows the poor root growth of ryegrass growing on a hillside.Some very weak roots do go down deeper but they are so weak and non fibrous that they cannot hold the soil.

Some thoughts on Evolution

Most evolutionary scientists accept Evolution as fact. Problems only arise when deciding how it occurs. There are several theories, and perhaps all may play a part,
though surely Darwin's natural selection acts in combination with the other theories, and is the architect.

When Mendel found the mechanism for variation, it solved Darwin's dilemma of not knowing what enabled the variations. Later neo-Darwinism was born with the uniting of Mendelism and Darwinism, which accounted for the gradual evolutionary change. Yet as Darwin knew with the breeding of dogs and pigeons that there is a great amount of variation stored in each species which enabled breeders to change their shape and size,.Plants and animals can adapt to the environment by making use of the great variation stored in the genes, but this is is not in itself evolution. If the environment changed back to its original status so would the species change back too.Over many many generations this adaptation may bring about a new species if separation prevented any gene mixing. I feel that its not just the appearance of the species that will make for a new species but a fundamental change in its physiology which will prevent it breeding with the species from which it was separated. That is why pigeons breeds have never become separate species.There would have to be a change in their physiology.

Punctuated equilibrium is another theory, advocated by Stephen J.Gould. This means that after a great extinction there where many niches open to the surviving species.They were able to explode into the vacant ground and evolution and speciation was rapid eventually ending in a period of stasis. This may well be correct with natural selection playing its part. During this so called stasis period slow evolution continued to fine tune with natural selection still the architect. Invasive plants do the same, moving out of their natural environment with all the constraints of co evolved partners, parasites and competition holding them in place,they are freed to adapt or even evolve to spread unhindered into their new environment.

Lynn Margulis makes a great deal of sense with her symbiogenesis whereby plants join together for their mutual benefit as in the Azolla fern in my pond.
Genetic variation is proposed to mainly occur as a result of transfer of nuclear information between bacterial cells or viruses and eukaryotic cells.
see also
Then there is the hybridisation of two species which produce more competitive individuals, which will eventually cause the extinction of the parent species and they themselves will become a species in their own right. Up to now it sees the only examples I have,have been brought about by man.
see article on wild radish
Killer bees were the product of the African bee and the European. Neither of these species were overly aggressive. I have had experience with both of them.The hybrid now seems to have adapted pretty well and has invaded much of the territory to the north from where it escaped.
see article on fire ants
read about how hybridisation improves adaptation
So these are cases where the evolutionary branches have actually joined together again. I'm sure this is a natural process occurring all the time but we can never find it in the act.read
radish

Gaia

Well James Lovelock and Lynn Margulis have written quite a bit about this.It was Lovelock's theory, ably aided a abetted by Lyn Margulis. Now I have to write and say what it means in a few lines today.

As I see it life began about 3500 million years ago plus or minus.Life started changing the environment it found itself in by gradually rusting the earth. Oxydising it until the excess Oxygen started accumulating in the atmosphere which had been mostly CO2 to begin with. Oxygen was of course toxic to many of the bacteria at the time an so made it more unfavorable for themselves but favorable for the creatures that evolved and were able to use the oxygen themselves.The earth as we know it now was created by life itself and is in a delicate balance.It seems to maintain that balance of temperature, pH,Oxygen, Co2, methane,hydrogen and a few other elements, mainly Nitrogen and the chemistry of the oceans. If the oxygen was to increase to say 30% everything from forests to grasslands would simply self ignite and combust. Below 15% we would find it difficult to exist.So our very existence depends on this balance, yet we are busy trying to change it through the distruction of the forests and life in the sea, soil erosion, pollution, burning of fossil fuels and so on.

Gaia acts as a self regulating living organism, but will it be able to self regulate if we change the environment to a point of no return or will it just shrug us off and carry on with out us. Take New Zealand as an example. Life that created the environment consisted of forests yet we have destroyed a greater part of those forests and replaced them with ryegrass and clover with little root system to hold the soil which is being lost at twenty times as fast as it was under forest. Can these pastures play as greater part in this self regulation as the forests?.

Soil Erosion in New Zealand

This picture shows old slips that have been revegitated with ryegrass and clover.

These pictures are an update of the latest damage done in Central Hawkes Bay by a water bomb. Some 600mm of rain fell in twenty four hours along the coast in May 2011. I intend to take more pics when I have the opportunity.The slips are not going to go away in a hurry.

This is how the temperate forests that once covered New Zealand looked like.Click the panoramic picture to see the full extent of the deforestation in the Hawkes Bay area.

We always associate deforestation with Third World countries and all the repercussions that go with it, but most developed countries deforestation occurred centuries ago and this is forgotten. Now with climate change and the extreme weather conditions with more frequent storms that go with it, the chickens are coming home to roost. New Zealand is a prime example. Once the whole of the two islands was covered with temperate forests, but with colonization by humans and the removal of these forests by slashing and burning, their replacement by clover and rye grass pasture gives the impression of a clean green land, and that everything is healthy.The picture above shows slips that have 'healed'. This whole area was once covered in thick temperate forest.



Erosion in New Zealand during the floods February 2004




The sheep have grazed the grass short and transformed the the hills into little terraces. The short grass means shallower root growth and less to hold the soil together.


Even though all appeared right, erosion was carrying on all the time. Before deforestation the rivers ran clear and deep, and in some cases could be navigated by small craft, but now they are wide and braided. River metal has filled the rivers which now continually change course and have to be kept in place by means of stop banks. At each heavy rain they fill up rapidly bringing down soil and stone because the water is no longer held in the catchments to be released slowly afterwards.


The rains and floods in the last few years in certain parts have been the heaviest in living memory, in one hundred years, or possibly since colonisation. Waipawa experienced in excess of 150mm in twenty four hours. It can be expected that these rains may now be of a more regular occurrence so that some thought will have to be given to deal with the problem at its source. Unfortunately this will impact on the whole country's immediate economy, namely the sheep. The sheep are dependent on the clover and rye grass, and the grass and rye grass grow mainly on the hill slopes of the hill country, from whence all the run off comes. Top Picture River in full flood carrying large amounts of soil. Below Normal flow





Bruce Levy wrote in1951 in his book '‘Grasslands of New Zealand',’ 'In a rain-forest climate, with its annual precipitation of between 35 in. and 200 in. of rain per annum, the all-important question is whether a thin veneer of grass
will stay a cycle of accelerated erosion as evidently took place in the initial sculpturing of our country's topography. There is evidence in districts where the ground consists of papa clay or mudstone that the grass sward cannot by itself hold the country together and prevent large-scale slipping and slumping to lower levels. On the other hand, there is ample world evidence to show that in most circumstances a sward of grass can preserve the earth's surface or can so slow up surface soil movement as to make the problem of soil erosion negligible. Our problem is to constitute and manage the turf so that it will serve the grazing animal and also maintain enough cover to stay soil movement. Where this is not possible, additional stabilizing factors, such as trees, concrete structures and earthworks must be provided. Much hill country is in a delicate state of slope equilibrium, and large-scale slumping occurs if this equilibrium is upset by removal of the stumps and roots, by the action of running water in cutting way of the toe of the slope, or by the degrading of the valley floor. Neither tree cover nor grass cover on the hills can avail against slope movement once the toe of the slope is undermined or the valley bottom deepens. Stability must be brought to the toe of the slope by work in the gullies'.

It can now be seen that this 'thin veneer of grass' cannot hold the country together under the increased precipitation that is likely to occur through climate change. The world evidence to show that 'A sward of grass can preserve the earth's surface or can so slow up surface soil movement as to make the problem of soil erosion negligible, has perhaps not been fully understood. The grass sward holding the earth together is usually a grass cover that has evolved through millions of years and is the natural vegetation made up of many different species with deep soil forming roots and taller top growth. This ' Sward of grass' holding the earth together is not the rye grass short enough to serve as a golf course fairway, that is supposed to hold New Zealand's hill country together.There may be a very good reason why the slips have increased in recent years. After deforestation the soil was underpinned by the roots of the forest trees which remained there for decades. It is known that the native trees are very resistant to rotting and are used for fence poles and last for decades.Once these disappeared the soil became very vulnerable to erosion.
Read More thoughts on erosion





These pictures are of the visible form of soil erosion,the invisible erosion is from the soil surface, washing off every time there is a heavy rain.
The present system of farming in New Zealand is not sustainable over the long term.

I have found more pictures I took after the floods of 2004. One shows even more damage than I saw in the others.It was taken with the telephoto

.



.

This picture shows the subsoil which is like marble size balls. When they become wet they are very greasy and slippery and during excessive rainfall they simply roll down the slope taking the top soil and grass with them..

.




.




.



.

This pic shows the root system of two African grasses, on the left and far right, Eragrostis curvula and centre Themeda triandra, root development is down two feet showing the tremedous ability to hold the soil together. The roots are very tough and fibrous.

This picture shows the poor root growth of ryegrass growing on a hillside.Some very weak roots do go down deeper but they are so weak and non fibrous that they cannot hold the soil.

The bottom picture shows attemps to stabilize the soil on old slips. This whole area has slipped and revegitated but is still in danger of slipping again. Poplar poles are planted into the area and these will root and bind the soil.

Paradise Ducks

The Paradise Duck

Tadorna variegata is a large gooselike duck native to New Zealand. It was discovered first by Captain Cook at Dusky Sound in 1773 during his second voyage. Cook called it the Painted Duck It was formally, before the settlement by Europeans, fairly rare but with the clearing of forests, the establishment of pastures and the construction of many thousands of small dams they have become very common indeed.

A species does not have to be alien to be invasive as the paradise duck shows, but on the other hand this increase in population has not damaged any ecosystem even though it may have become a nuisance to farmers.The alteration of the environment by man has opened up more space for the ducks to move into.The ducks may also have adapted or evolved to fit this new environment. A census in 1981 showed that there were 70000 on the North Island and 50000 on the South Island and numbers have increased considerably since then. Hundreds of pairs can sometimes be seen grazing on pastures. And will raid other crops particularly when moulting In fact, special paradise duck hunting seasons are necessary to stop large mobs damaging farm paddocks with their grazing.

They live in pars staying together for life though it is said that the male is more faithful than the female in that if the female is injured the male will remain with her but if the male is injured the female will soon find another healthy mate. They reach sexual maturity at two years, and build nests in long grass,underneath logs or sometimes in trees, lining the nests with grass and down. Chicks fledge at eight weeks. Like many other duck they will feign injury and use this guise as a decoy to protect their young, taking the danger on a ‘wild goose chase’.

Both the male and female have striking plumage, the male has a black head and barred black body with white on the wing when flying, the female a white head with a chestnut or bronze body. Their calls are diverse, a deep ‘zonk zonk’ from the male and a shrill ‘zeek zeek’ from the female.