Overview of the Carbon Cycle

Reduced to its simplest form, the Carbon cycle describes the flow of Carbon, and the gas Carbon dioxide, through the organic processes that happen in our world.

The Oxford English dictionary definition of the Carbon cycle is, “The movement of carbon through the surface, interior, and atmosphere of the Earth. Carbon exists in atmospheric gases, in dissolved ions in the hydrosphere, and in solids as a major component of organic matter and sedimentary rocks.” So we’re already looking at Carbon in the air, in earth, in rocks, and in water.  As ions in solid and gas form.  Maybe that illustration won’t be so straight-forward after all.

Early thumbnail sketch trying to incorporate the different elements of the Carbon cycle

When plants and animals die, they rot down, depositing carbon into the soil.  This travels and seeps through the soil, and although some is used by micro-organisms, fungal hyphae, and roots in the soil; some turns into sedimentary rocks.  Over time, some will be compressed and form fossil fuels.

Now we need to introduce Carbon dioxide, a gas, into the cycle.  This is exhaled by animals, both below the soil on a microscopic scale, and on land (and in water and air), on microscopic and macroscopic scale. Carbon dioxide (CO2)  is used in photosynthesis.  This image is getting complicated.

Completed tree with roots, fungal hyphae, and leaf litter.  No gas clouds added…yet

The Carbon cycle and Photosynthesis and Cellular Respiration

An extra and vital step in the Carbon cycle is the role of both photosynthesis, and respiration.  Photosynthesis occurs within green leaves and produces sugar and Oxygen in sunlight, created from water and Carbon dioxide.  Respiration is practised by all living organisms (including plants) and is almost a reversal of photosynthesis.  Oxygen and sugar are broken down to release ATP (whose purpose is defined in the Encyclopedia Britannica as, “ATP captures chemical energy obtained from the breakdown of food molecules and releases it to fuel other cellular processes.”)  By-products are CO2, and water.

Diagram showing the process of photosynthesis (purple arrows are glucose, red arrows CO2, pale blue arrows O2 and dark blue arrows show water)

Perhaps an easier way of showing photosynthesis is using an entire plant?  At this stage, I’m wondering how to streamline the cycle and manage to show all the elements involved.  Looking at work I’ve done in the past for other jobs (like this leaf and plant diagram) is really helpful, although provides no instant solution to the challenge.

Annotated Photosynthesis diagram using the Japanese Knotweed

Untangling the steps of the Cycle

Having got my head round what needs including, I have to decide the best way to do this.

I want the entire illustration to be more or less cyclical, although it’s not as clean-cut as perhaps an illustration of the water cycle might be.  So the central image needs to be a tree.  Let’s make it stately, with plenty of room under the soil for roots, and enough of a canopy above to give space to include information on photosynthesis and respiration.  I illustrated a tree which will provide the perfect scaffold for the cycle last year.

White Oak Quercus alba with stylized root system

Other images can be shown as vignettes.  It’s important to make this picture visually pleasing as well as comprehensible, so I’ll balance the vignettes.  One on either side below the soil.  A mirrored pair at soil level.  And two overlaid on the tree canopy.  Sounds like a plan.

Vignettes: Below the soil: Micro-organisms

One shows soil micro-organisms.  These use Carbon from the tree and the soil to build themselves.  They also release Carbon when they die, and as CO2 from respiration.  Organisms living in the soil like this are often tiny, and can be simplified to six main groups.  Bacteria, virus, algae, fungi, protists, and nematodes.  It goes without saying that there is vast variety in each group, and these vary from habitat to habitat.

Micro-organisms in the soil

So I show a simplified representative of each.  The virus look like spiky balls.  Bacteria are spherical or rod-shaped.  The fluffy spores and hyphae on the right represent fungus.  Protists are shown by the flagellates in the centre.  Algae are represented by the diatom at the top left and the volvox-like organism by the hyphae.  Wriggling behind, we have the head end of a nematode worm.

Vignettes: Below the soil: Roots

The sister vignette on the opposite side shows a close-up of a root-tip.  It grows (using Carbon), practises respiration (producing CO2) and dies (releasing Carbon).   I can’t really show it dying in such a small space.  I’m hoping accompanying text will cover this.  The root tip cells which slough off should suggest this senescence, if the viewer knows about root anatomy.  Each root cell has a cellulose cell wall, a central space or vacuole, and cytoplasm around the edge.  In truth this is a gross simplification.  Cells in the root tip can become Parenchyma cells, which absorb and carry nutrients.  Or they can be Sclerencyma cells, which form the cell wall.   In the cytoplasmic matrix are all the cell’s organelles, along with a nucleus.

Cellular image of a root tip

The lateral projections are tiny root hairs.  These increase the surface area of the root, and allow for absorption of water and nutrients from the surrounding soil.

At the tip of the root you find the root cap.  This area is vital to plants.  Information as to gravitational and growth response occurs here, along with responses to different external environmental stimuli.  The root cap also protects the growing meristem cells.  Root cap cells are short-lived, being sloughed off  and destroyed as they nose their way through tough soil particles.  In the root cap you also have acidic hydrogen ions.  These break down the soil chemically, which allows minerals and nutrients to be absorbed by the root hairs.  For more on the structure of root tips, please visit the ehow site, or this overview from the Journal of Experimental Biology (June 2015, Kumf and Nowak).

Vignettes at Soil level: Detritovores

Mirrored vignettes at soil level show detritovores which break down Carbon from fallen leaves and twigs.  These are just flipped around the central axis of the tree trunk.  The creatures in this assemblage also breathe, exhaling CO2.  When they die, they release Carbon back into the soil.  And, of course, they use Carbon in the soil to build and grow themselves.

This is my favourite part of the illustration.  I get to cram lots of delicious invertebrates into this vignette.  Despite my best efforts, this illustration only touches the surface of the animals that make their home in the leaf litter and surface layers of soil.  As before, it’s grossly simplified.  Every habitat, in fact every plant, may have a different assemblage of detritovores associated with it.  This activity from Scientific American tells you how to see what decomposers are in your local patch of leaf litter.

Detritovores in the leaf litter

Representatives I include here are based on invertebrates I find most often when scrabbling about in leaf litter.  And ones I love illustrating.  So there are snails and slugs.  Spiders and mites.  We have a woodlouse (I love woodlice as they carry their developing young around with them, slung in a brood pouch).  And an earthworm.  I could have included another Nematode, but the scale made it tricky.  We have ground beetles, some of whom are ferocious predators, capable of slicing a slug in half with one snip of their mandibles.

Earwigs scuttle about, as do the remarkable Psedoscorpions.  There are millipedes and centipedes.

Detritovores that don’t get included

As with all of these vignettes, it has to be simplified.  Remember in fact that even within this assemblage you have herbivores (like the millipede) and carnivores (like the centipede).  Hunters (like the ground beetle and spider) and prey (the slug).  You even have parasitic relationships going on, with mites exploiting ground beetles.

Centipede

Some sources, such as Frontiers, prefer to show the leaf litter as a cycle in its own right.  This makes sense, especially when we remember that there are the same micro-organisms at play in the leaf litter, along with fungal and tree activity.

Lots of fabulous invertebrates, like springtails, thrips and ants, failed to make the cut.  For an overview on detritovores by the Biology dictionary, click here.

Soil level: The importance of fungus

At soil level, other things need to be included if we’re going to see the Carbon cycle as a whole.  Fungus is front and centre.  It’s only comparatively recently that the intense and vital relationship between roots of plants and of fungus is coming into view.  Brilliant books like “Entangled Life” by Merlin Sheldrake have popularised it, and we’re now realising that fungus plays a massive role in allowing communities of trees and other plants to communicate at a sub-soil level.

Irrelevant of communication, fungus are also indispensable to the carbon cycle.  Their hyphae spread out under the soil, going massively further than the surface-level fruiting bodies might suggest.

Fungus with hyphae diagram

These mycelium break down wood and other organic matter.  They can also store and disperse these nutrients.  At this point in my research I also clocked that, if I was going to do this right, I ought to tie in the Nitrogen and Phosphorous cycles.  But you have to draw a line somewhere!  Mycelium move Carbon and other nutrients cover vast networks, using them for their own growth and delivering them to plant roots.  It’s well understood that plant and fungal roots are symbionts.  For more on how these sharing networks can be studies, check out “The role of wood decay fungi in the carbon and nitrogen dynamics of the forest floor” by Watkinson, Bebber et al (2009)

Fungus in my Carbon cycle illustration

I choose a few representative fungal species I see often in leaf litter.  These include notorious wood rotting species like the Honey fungus Armillaria mellea, which attacks living as well as dead wood.  There’s a representative Russula species, and a Shaggy Ink cap Coprinus comatus.

Fungus in the Carbon cycle

I also include the Fly agaric (on the opposite side of the illustration), because it’s so instantly recognizable as “fungi”.  This is disingenuous.  Agarics have lost the enzymes needed to decompose leaf litter, and are wholly reliant on their tree hosts for nutrients.  With the network or entangled roots described above, they’re the epitome of a symbiotic relationship between tree and fungus.  The fungus carry nutrients to the tree, the tree feeds the Fly agaric. (Read more on this on Woodlands.uk blog).

Fly agaric Amanita muscaria

I pop in some representative lichen.  Lichen is a symbiotic organism, composed of algae and fungus (or cyanobacteria).  Their role in the Carbon cycle is less as a decomposer, but more as a Nitrogen and Carbon fixer. They’re vital to both cycles, so need including, but on a diagram of this scale there’s no space to explain that rather than rotting down wood and leaves, they’re more important for their role as photosynthesizers.  The same is true of the tufts of moss I include.

Soil level: Larger animals and death

Obviously, it’s not just the micro-organisms and invertebrates in the leaf litter that contribute to the Carbon cycle.  Larger animals exhale CO2, and when they rot, they’re turned back into Carbon and basic nutrients by animals living in the leaf litter.  Some specialised creatures, like the rather glorious Sexton beetles, have eveolved to fit this ecological niche. I choose a rabbit as my larger animal representative, and just the other side of a log, I add some bones to show how death and decay feed into the cycle.

Bones

Soil level: Leaves

It’s self-evident, but probably worth mentioning that the main component of leaf litter is…leaves.  There are twigs, branches, dead detritovores and a host of other goodies in leaf litter.  But your main component are leaves.  These need to be shown as they rot down, but also falling from the tree, bringing their own personal packet of Carbon to the ground.

Falling leaves adding to the leaf litter layer

I include leaves from other species too, easily representing this in a simplified form by varying the leaf margins.  I make some fresh and green, and others browned or yellowing, referring to the glut of carbon-rich leaves which fall every autumn.

Now, finally, we can cast our eyes upward.

Vignettes at Sky level: Photosynthesis and Respiration

I want to include visual information on Photosynthesis, but representing it in diagrammatic form proves tricky, and too complicated.  This is also true of Respiration.

Initial Thumbnail rough Carbon cycle

I’m relieved when the client asks if we can replace the leaf cross sections you can see in the rough above with the equation for each process.  However, I don’t want the space around each equation to feel dead, so I provide simplified motifs for Carbon dioxide, Oxygen, Sugars (C6 H12 O6), Water (H2O), and ATP.

Simplifying photosynthesis

For the record, the equation for Photosynthesis, which occurs thanks to chlorophyll, in the presence of sunlight, is CO2 + H2O = O2 + C6 H12 O6 (glucose).  Respiration, occurring in plants as well as animals, is O2 + C6H12O6 = H2O + CO2 +release of ATP.  And no, I’m not tempted to get into the details of how turning ATP into ADP gives living organisms the energy they need to exist!  If you want more on that chemical process, also known as Hydrolysis, find it here.

Simplifying respiration

The last thing that needs adding to the carbon cycle illustration is, oddly, a suggestion of day and night.  This is because photosynthesis can only occur in the presence of sunlight.  And, in most plants, respiration occurs mainly at night.  I add a little sun above the Photosynthesis equation, and although I want to add a little moon above the respiration one, this is vetoed by the client.

Done.

Annotated Carbon cycle illustration

Conclusion

So several rabbit holes and a whole lot of research later, I finish my Carbon cycle illustration.  It’s too simple and doesn’t reflect the complexity of nature.  It fails to reference the interactions between the Nitrogen, Phosphate and Carbon cycle.  It doesn’t show the ongoing inter actions on a smaller scale, or how each living animal is exhaling CO2, and rotting down to Carbon after death.  I’ve more or less left out the Carbon getting trapped in soil, and rocks.  I’ve only given a superficial nod to the accumulation of carbon in the soil in rocks which get compressed to form fossil fuels  And when I introduce arrows, I feel the whole image becomes more, rather than less complicated.  But nature doesn’t keep to clean, proscriptive shapes; there are endless exchanges on a smaller level, and fascinating details like fungus, lichen, and insect parasitism to consider.

Finished and annotated carbon cycle

However, as an exploration and an illustration to accompany those four little words,. “illustrate the Carbon Cycle”?  I think it’ll do.

And here it is, on the pages of the Tradgardens Klimatnytta brochure, produced by Riksforbundet Svensk Tradgard.  The brochure will be published soon.

Carbon cycle page from the TRÄDGÅRDENS KLIMATNYTTA brochure, produced by Riksforbundet Svensk Tradgard

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Ink and watercolour is a classic, intriguing combination that creates some really amazing effects when accomplished with the right tools.  Black outlines define a beautiful watercolour painting that jumps off the page!

Fig illustration with top wash of watercolour

Do you want to know how you can create ink and watercolour pieces that affect people?  Well, you are going to need the right tools for the job.  I am going to walk you through what makes for a good watercolour pen and review my top pens and ink that are designed for watercolour work.  Let’s begin!

What Makes for a Great Watercolour Pen and Ink?

What makes for a good pen or ink when it comes to watercolour?  Here are the things to consider:

What Makes for a Great Watercolour Pen and Ink: Waterproofness

Arguably the most important, you want to find ink pens or ink bottles that are labeled waterproof.  It can get confusing as they may say “water-resistant” as well as some terms that mean the opposite, which we look at in the next section.

You need a waterproof pen or ink so there is no bleeding or smudging of any kind when you apply your watercolours to it.  A quality ink will allow you to draw beautiful, strong lines without any bleeding or transfer of colors.

Crab with top wash of watercolour

What Makes for a Great Watercolour Pen and Ink: Avoid “Water-Soluble”

It is likely you’ll come across a couple inks and pens that are labeled water-soluble or water-based.  Avoid these like the plague!  Water-soluble inks and pens are made with water and will run when you start painting with watercolour.  A safe rule to follow is that any pens you find that don’t state they are waterproof or water-resistant are likely to be water-soluble and won’t work well with watercolour paint.

Small tortoiseshell butterfly Aglais urticae life cycle illustrated in pen and ink with watercolour top wash.  If the inks had bled, the butterfly would have been a disaster.

What Makes for a Great Watercolour Pen and Ink: Pigments

It can be, at times, unclear if the pen is waterproof, especially with foriegn pens or inks.  You can look for “pigments” or “pigmented ink.”  If a pen or ink is labeled that it is made with pigments, this is a sign that a pen is very likely waterproof.  Pigments are tiny colored material that does not dissolve in water, so they are not water-soluble or water-based.

What Makes for a Great Watercolour Pen and Ink: Ink Dry Time

Another thing to consider is how long the ink takes to dry!  Applying watercolour too soon can cause bleeding, fading, or smudging.  For most inks, you want to wait at least an hour or two hours for the ink to dry onto the paper.  If you are a fast sketcher or just want better dry times, there are fast-drying inks that only take a few minutes to be completely dry and smudge-proof!  We recommend our top fast-drying ink below, so keep reading.

Red spider mite Tetranychus urticae pen and ink with watercolour top wash.  The fast-drying ink dried within 20 minutes, allowing immediate work into the illustration.

What Are The Best Waterproof Pens For Watercolour

Let’s review the top-rated pens to use for an ink and watercolour project.  We suggest trying out a couple of these so you can find your personal favorite!

1. The Uni-Ball Signo Gel Pen

On the top of our list we have a great, beginner friendly gel pen that works wonderfully for any watercolour project.  The Uni-Ball Signo is an affordable waterproof pen that draws straight clean lines that never gives unwanted ink blots on your paper.  We’ve found the Uni-Ball to be a favorite for quick ink and watercolour work that we can always rely on and have several laying around.

2. Sakura Pigma Fineliner Micron Series

Our second on this list is a fineliner, particularly the Micron Series by Sakura.  A fineliner is a great type of pen that creates beautiful, professional lines that are straight, thin and just look great.  The Sakura Pigma is completely waterproof and we’ve found it to be one of the best pens to use for ink and watercolour paintings.

Sakura pigma Micron 0.1 inkpen, used to do the ink work under the top watercolour wash on this Cherry illustration

3. Fountain Pen by Visconti

We recommend considering a fountain pen that you can load up with your own ink.  If you foresee working with ink for more than a year, disposable pens get expensive, and the very best ink for use with watercolour can only be bought as an ink bottle (not to mention with a fountain pen, you can get various colored inks to play around with!).

Oil seed rape Brassica napus.  I use disposable pens and get through 20 – 50 a year depending on the jobs I get commissioned to do.  Maybe I need to consider shifting to a fountain pen?

Our favorite fountain pens are from the company Visconti.  Our favorite fountain pens for watercolour artwork are the Visconti pens from Goldspot Pens.  Visconti has a diverse range of fountain pen options.  A fountain pen works wonders for ink and watercolour projects.  You can scroll down to our ink suggestions and combine it with a fountain pen ink and the result is unbeatable.

4. Uni-Ball Impact Gel Pen

This is another great gel pen option for watercolour.  The pen is completely waterproof and fade-proof.  You should consider giving the Impact Uni-Ball Pen a try. But before you buy, you need to check out drawings made with it, as the lines are broader than many gel pens and may not be the best for very detailed ink work.  The Impact does amazing outlines and so makes for a good little watercolour pen.  It can work especially well for cartoon or comic styles.

5. Tombow Fudenosuke Brush Pen

Using a brush pen for your ink and watercolour work is a really neat option that I know some of you will want to go with.  Tombow’s Fudenosuke pen is a seriously great option for watercolour.  It is waterproof even though the labeling is fairly confusing as it mentions water-based and pigmented ink, but we went with it and it does great with watercolour paints.

A brush pen is a neat option that gives you the new ability to change the width of the line you are drawing by changing your pressure applied to the pen.  This allows for some really creative use of ink and watercolour that I’d love to see how people use to make unique ink brush and watercolour creations.

Mallard duck Anas platyrhynchos duckling.  This illustration was done in pencil, but would be a perfect candidate for a brush pen.

6. The Unipin Fine Line

This is an interesting and fun waterproof pen we found and really enjoyed.  The drawback is that when using an eraser we find the ink fades and blurs, but if that’s not a problem, this is a great pen for your project.  It draws really nicely and feels natural in your hand.  The Unipin Fine Line is definitely an option to consider.

Quince pen and ink illustration with watercolour top wash – completed using my favourite of these recommendations – the Unipin Fine Line 0.1

7. Winsor and Newton’s Fineliner

I am a big fan of Winsor and Newton and find their products to be a great addition to any artist’s toolbelt.  Their new finliner works great with watercolours, so I had to include it on this list.  Even better, the fineliner comes in various sizes and colors that you can choose on their website!

Winsor and Newton’s new fineliner pen works with watercolour really well and is an overall very professional pen that you can use for your next project.

Rainbow agama lizard Agama agama pen and ink.  Completed some years before Winsor & Newton bought out their fineliners, but now I’m excited to try similar subjects with these new pens.

8. Pocket Brush Pen from Pentel

I needed to add another brush pen to this list because they’re so fun.  The Pocket Pen from Pentel is a keeper.  The pen was originally created to be used for japanese calligraphy and draws beautiful brush strokes and is made with waterproof ink that is suitable for watercolour.  The brush tip is very sensitive so it easily changes the width of your lines.  This is both a pro and a con.  It gives you so much control and feels great when you master it, but it is easier to make a mistake.  We highly recommend this pen if you are used to drawing with brush pens.

9. Parker Pens

If you are enticed by the idea of a fountain pen to use with watercolour, another top recommendation is the Parker fountain pen from Goldspot.  Kaweco is a historic brand that has been known to produce very smooth and beautiful drawing and writing pens for over 100 years.  The Kaweco Sport and Kaweco Liliput are two fountain pens that are praised for their beautiful drawing lines.  If you get one of the best inks for watercolour into one of these pens, it becomes a very good option for ink and watercolour.

Parker pen

10. Assorted Pens from Faber-Castell

Faber-Castell is a truly historic brand that was founded in 1761.  You heard that right, this pen company was founded over 250 years ago!  They are still crafting beautiful pens, from fountain pens to fineliners and brush pens.

The Pitt Artist Pen set they released is an amazing set of fineliners and brush pens that are all waterproof and made with high quality India Ink.  This is definitely a good option for ink and watercolour, and it gives so much variety to play around with!  You get 4 fineliners and 4 brush pens that gradually increase in size.  Faber-Castell has a history of great craftsmanship and with these new waterproof pens, you have an alluring option to check out.

Cedar of Lebanon pine cones with watercolour top wash – completed with Faber & Castell Ecco pigment 0.1

Best Ink for Watercolour

What matters most with any of the pen options we looked at in the previous section is the ink that’s in them.  For many of them, you can’t be certain you are really getting the highest quality ink.  In my experience, the best ink for watercolour comes in a bottle right from the manufacturers.  Here are our top picks for a waterproof ink to use with watercolour.

Wind pollinators showing close up of individual flowers

1. Platinum Carbon

Our top recommendation is Platinum Carbon Ink.  This is a black ink that has a beautiful texturing done over it that gives it a pure natural black appearance.  Platinum Carbon is a permanent waterproof ink resistant to any smudging, fading, or bleeding.  Needless to say, it works incredibly with watercolour.  If you don’t know which ink bottle is for you, this is our recommendation.

Platinum carbon ink

2. de Atramentis Archive Ink

The de Atramentis Archive is another of the best ink options for watercolour.  This is a black ink that has less texturing than the Platinum Carbon while still presenting a professional matte black appearance.  The number one benefit to this ink is that it is extremely waterproof and a fast-drying ink.  This ink dries in just a few minutes and can be used with watercolour right after for no distortion or transfer of color at all.  Out of all the inks on this list, the de Atramentis may just be the most waterproof and fastest drying.

Plum Prunus domestica.  Pen and ink with watercolour top wash.  Fast drying inks really simplify this technique!

3. Speedball Super Black India Ink

Our top recommendation for a pure black ink is Speedball’s Super Black India Ink.  Most people don’t know that most inks that are in pens are actually made with black mixed with various other colors like blue and grays.  If you want truly pure black ink, you want to go with India ink.  Speedball has made a great waterproof India ink for use with watercolours that you should definitely check out.  It is a solid black that makes for some very strong borders and outlines.

4. Sailor Kiwa-Guro

I really like Sailor as a company.  They are a historic Japanese brand that creates top-quality fountain pens and inks.  The Sailor Kiwa-Guro is a really great ink that is fully usable for watercolour and ink artwork.

Kiwi-Guro by Sailor

The only problem with it is that it has been reported that if you leave it in the bottle for several months, it can lose its waterproofness.  This brings it lower on my list as this could be a real problem for watercolourists who are looking for a long-term ink for their work.  If you do not mind that, this is an amazing ink that looks beautiful with watercolour.

Ink retaining its’ waterproof quality is essential for diagrams such as this male House sparrow done for the RSPB Spotlight Sparrows book

5. Winsor and Newton Ink

We have another high-quality Winsor and Newton product: this is their high-quality waterproof ink.  The Winsor and Newton ink is a great beginner ink.  It has a cute matte black color to it that looks really good for cartoon or comic styles, and modern styles.  The ink takes two hours to dry, but is a great waterproof and fade-proof option when it is completely dry.

How To Find The Right Pen and Ink For You

The most important thing in buying any art supplies is finding what works best for your style and preferences.  I advise that you research several of these pens and inks to find what’s best for you, and, if you have the opportunity, I would recommend picking up a few of these so you can try out first-hand which is your favorite.

Let us know in the comments which you found to be your favorite!  We hope you find your perfect pen and ink for your artwork.

Ladybird Coccinella septempunctata diagram with outstretched wing in pen and in with watercoloour top wash

The post Equipment: How to Choose a Waterproof Pen and Ink for Watercolour appeared first on Lizzie Harper.