Beyond the Tower of Babel …

A week after I return from China, I was off on my travels again; this time to Vienna for a workshop between molecular ecology specialists and ECOSTAT, the committee of Member State representatives who oversee ecological aspects of Water Framework Directive implementation.   As ever, I found some time to visit some art galleries around the meeting and, as Vienna has one of the most impressive collections of paintings by Pieter Brueghel, I could not resist spending some time in front of his “Tower of Babel”.  A few years ago I cheerfully included this picture in a talk on EU ecological assessment methods, as we tried to make sense of the myriad national approaches.   Three years after the Brexit vote, however, it seems to better reflect UK domestic politics where, ironically, language is one of the few things that all protagonists do have in common.

The River Danube seems to encapsulate the reasons why Europe needs collaborative thinking on the state of the environment.  It is the second longest river in Europe, after the Volga, and flows through ten countries, with tributaries extending into nine more.   Eight of the nine countries through which the river flows are members of the EU (the ninth, Serbia, is in the process of joining) so the river represents a case study, of sorts, on whether EU environmental policies actually work.   This is not just an academic question: ecologists are generally in favour of integrated management of entire catchments whilst the EU operates on a principle of “subsidiarity”, which means that decision-making is devolved to the lowest competent authority (individual Member States in the case of the environment).   Finding the right balance between these principles takes a lot of patient discussion and is one reason why EU decision-making can appear to be agonisingly slow.

Pieter Bruegel’s “Tower of Babel” in the Kunsthistorisches Museum in Vienna.

And there are more problems: the Water Framework Directive evaluates the sustainability of water bodies by their naturalness yet very large rivers such as the Danube have been very heavily modified by human use for centuries.   The river has been broadened, deepened and impounded, and its banks have been straightened and strengthened in order to make it navigable, and there is a huge human population, with associated industry, living on its banks.  The stretch of the Danube along which I walked on my last morning in Vienna was also lined with embankments to protect the surrounding land from flooding but these, at the same time, cut the river off from the ecological benefits of the floodplain.

What hope for a large river such as the Danube in the face of all these challenges?   First of all, when dealing with rivers such as these we need to adjust our expectations, recognising that they are so central to the economic life of the regions through which they flow that there are limits to their capacity to ever resemble truly natural rivers.   Once we have done this, we can start to unpick the challenges that can be addressed by individual Member States.  In the case of water quality, in particular, the story for the Danube is encouraging and European environmental legislation has played its role in this process.  By the time the Danube reaches the borders with Romania, for example, nutrient concentrations are low enough for many of the benthic algal-communities to meet criteria for “good ecological status”.

You can see this in the graph below, from a paper that we’ve published recently.   The Romanian sites are largely clustered at the top left hand side of the graph, relative to data from other countries – indicating low phosphorus concentrations and good ecology (expressed as “ecological quality ratios”, EQRs).   Thanks to an extensive exercise that took place a few years before I started grappling with the Romanian data, we already had a consensus view of the EQR boundaries for high and good status, and most of the Romanian data fits into the band representing “good status”.  That’s encouraging and whilst these communities are just one element of a much more complex ecosystem, but it is a clear step in the right direction.

The relationship between dissolved phosphorus and ecological stataus of the phytobenthos (expressed as the Ecological Quality Ratio, EQR, based on the intercalibration common metric (which gives a harmonised view of status between Member States).   Horizontal lines show the average position of “high” (blue) and “good” (green) status boundaries.   RO = Romanian data; XGIG = data from other Member States.   See Kelly et al. (2018) for more details.  

Romania is, of course, a long way downstream from where I was standing in Vienna.  Before the Danube gets there it has to cross Slovakia, Hungary and Serbia.  The river also forms the boundary between Romania and Bulgaria for about 300 kilometres, so it is important that there is joined-up thinking between those responsible for water quality on the two opposite banks.  That’s why the EU is so important for the environment on a pan-European scale.  It is easy for those of us crammed onto our insignificant archipelago in the north-west corner of the continent to overlook this, but the Danube is really a great success stories for European environmental collaboration and, indeed, a reason for staying with this ambitious project into the future.   Too late, I know, but it needs to be said.

Reference

Kelly, M.G., Chiriac, G., Soare-Minea, A., Hamchevici, C. & Birk, S. (2018).  Defining ecological status of phytobenthos in very large rivers: a case study of practical implementation of the Water Framework Directive in Romania.  Hydrobiologia 828: 353-367.

Sightseeing in Vienna: Stefansdom, the historic cathedral in the city centre and the Ferris wheel at the Prater amusement park, which played a starring role in Graham Greene’s The Third Man.

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The limits of science …

Back in a rather smoggy Chengdu I find it easier to describe the environmental problems that China faces than it is to propose solutions but perhaps that is the nature of my calling. Coming from a scientific background, I tend to think primarily in terms of technological ‘fixes’.  I help to define ecological and chemical targets in order that a motley band of regulators and engineers can restore a lake or river to good ecological status.  But these targets, as is the case with most legislation, really define the lower limits of acceptable behaviour, setting a threshold for the point at which the state should intervene to limit bad behaviour.  Achieving ecological targets does not, necessarily, equate to morally good behaviour.

This brings to mind a quotation from the US environmental lawyer Gus Speth: ‘I used to think the top environmental problems were biodiversity loss, ecosystem collapse and climate change. I thought that with 30 years of good science we could address those problems.  But I was wrong.  The top environmental problems are selfishness, greed and apathy … to deal with these we need a spiritual and cultural transformation – and we scientists don’t know how to do that.’

The only part of that statement with which I disagree is the need for 30 years of good science. In the case of aquatic ecosystem health, I think we already know what needs to be done in broad terms.  Reconciling the investment required with the ‘willingness to pay’ is as big a challenge in China just as much as in Europe.   Willingness to pay recognises that environmental improvements come with an ‘opportunity cost’ – a pleasure that has to be foregone.   And by focussing attention on selfishness, greed and apathy, Gus Speth is spot on, for China just as for the West.

The irony of the situation in China is that two of its most prominent religions – Buddhism and Daoism – have a philosophy that should, in theory, provide a justification for a less materialistic lifestyle but which, somehow, exist in an uneasy equilibrium with modern China’s capitalism.  This is amply summed up by the photograph at the top of this post: showing the Daci Bhuddhist temple close to the centre of Chengdu overlooked by the gleaming skyscrapers that encapsulate modern Chinese capitalism.   The monks and continue their devotions just a few metres from an upmarket shopping mall that has been built around this temple complex, complete with Western brands such as Gucci, Dior, Louis Vuitton and Cartier (see “Reflections from the banks of the Yangtze” for another of these paradoxes).

The shrine to Guanyin, goddess of mercy and compassion, at the Yuántōng Temple in Kūnmíng. 

It maybe that we in the West see Buddhism, in particular, through rose-tinted spectacles.  The reality is that most Chinese are only nominally Buddhist (often with a seasoning of Daoism and Confucianism too) rather than strict in their adherence.   Somehow, these eastern religions co-exist with materialism, just as Christianity does in the West.   The infrastructure of all religions depends upon individuals producing more than they need for basic sustenance and being prepared to donate part of the surplus as ‘alms’ or ‘tithes’ in return for the benefits that the religion confers.  This is exemplified by the prominent shrines to Guanyin, the goddess of compassion and mercy (roughly equivalent to the Virgin Mary in Catholicism) and a mediator between worshippers and the divine.   The temple becomes a focus for transactions, rather than for reflection and transformation.  In this way, Buddhism can be one more part of a system that indirectly encourages wants and desires even if the religion, in theory, is about transcending these.

I would encourage you to read Kate Raworth’s Doughnut Economics, for an inspirational look at how modern economic theory has resulted in an unsustainable situation.  She also proposes solutions yet, for these to work, each of us will have to accept that creating a sustainable world will carry a considerable opportunity cost.  That will mean an adjustment in expectations, and a need to find a source of contentment that is independent of materialism.   The environment, to be blunt, cannot be considered without also thinking about economics.  At the same time, radical thinking about economics will need to be accompanied by a deeper shift in behaviour and attitudes if it is to succeed.  That pushes us to the very edges of rationalism, and into the realms of mysticism.

And, yes, this whole post was written in China so I have to admit to an element of hypocrisy if I am to write about a more sustainable world whilst still indulging in long-distance air travel.  More about that in a future post.

Pagodas at the Chongsheng temple complex at Dàlī, with Ērhāi Hú in the background.

The Chongsheng temple complex at Dàlī, against the backdrop of the Cāng Shān mountains.

Approaching the tipping point?

From Kunming we travelled by train 200 km to the east, to Dàlī, which sits between Ērhāi Hú (literally ‘ear-shaped lake’), another of Yúnnán’s plateau lakes, and the Cāng Shān mountains.  These rise to about 4000 metres and still, even at this time of year, have patches of snow near their summits.   Dàlī’s old city has escaped the ravages of modernisation that have blighted many Chinese cities and we spent hours wandering the narrow streets lined with the traditional Bai architecture, along with a very large number of Chinese tourists.

On one day we hired bicycles and cycled along quiet roads lined with market gardens to reach the lake, then turned north and followed the lake shore for about five kilometres.  There were many areas of semi-natural shoreline along this stretch, with a fringe of wetland, but the filamentous algae (mostly Cladophora) coating the rocks that had been piled up along the settled parts of the shoreline told their own story.  This lake is clearly in better health than Diān Chí but it, too, is nutrient-rich.

A fringe of filamentous algae, along with floating leaves of Trapas natans(Eurasian water chestnut) growing on a jetty beside Ērhāi Hú.

Just after midday we pulled into a small family-run restaurant at the edge of a village.   A short conversation between the waitress and Ed (our only Mandarin-speaker) revealed that they specialised in serving fish from the lake so that seemed to be the obvious choice for our lunch.  The waitress disappeared, then reappeared with a net which she dunked into a tank behind our table and, with a couple of deft flicks, pulled it up with two carp wriggling inside.   These she quickly dispatched, cleaned and took into the kitchen.   About twenty minutes later she reappeared with a delicious stew comprising the whole fish cut into chunks, a generous seasoning of dried red chilli and tongue-numbing Sichuan pepper, lightly-pickled vegetables (white radish, celery and turnip) and some green leaves.   This, along with rice and endless green tea, and with Ērhāi Hú as a backdrop, created a perfect lunch for appetites whetted by our exercise.

From tank to table in twenty minutes: our fish stew made from carp from Ērhāi Hú.

We had seen some locals fishing with poles, and there is also some commercial fishing using cormorants in the area. However, the abundance of fish on the menu confirmed my hunch that the many booms we could see across bays along the lakeshore were fish farms (maybe ‘fish ranches’ is a more appropriate term when the fish have, relatively speaking, plenty of space in which to roam and forage).   The nutrients pouring into the lake here are, at least, able to support a economically-viable industry rather than undermine the supply of resources, as is the case for Diān Chí.

Of course, the story is not that simple.   In the past, Ērhāi Hú, like Diān Chí, had some endemic species, found nowhere else, but these have not been recorded for about 20 years.   Pollution from surrounding cities is the most likely explanation and, if Ērhāi Hú is in a better state than Diān Chí, then this is partly because the lake is larger and deeper, the catchment area is bigger and the scale of urban development is smaller (Dàlī is about a twentieth of the size of Kunming).  That said, local scientists have identified a significant declining trend in water quality, particularly over the past 25 years.   Importantly, however, they also note that it is not too late to do something about the situation.

Fishermen cleaning their nets beside Ērhāi Hú.  

In brief, nutrient concentrations in Ērhāi Hú are increasing. That leads to a more productive ecosystem which is, up to a point, good for commercial fishing but also means that oxygen concentrations drop, which is bad for the fish.   High nutrient concentrations also mean more algae but, at the present, these are not so high that cyanobacterial blooms develop as they have done in Diān Chí.  That means that the water in the lake can still be used as a drinking water supply for Dàlī and its environs.   However, if nutrient concentrations rise further then oxygen concentrations may pass a tipping point when it becomes almost impossible to manage lake phosphorus concentrations.

This is because phosphorus and other nutrients accumulate over time in lake sediments.  Phosphorus is not very soluble in the presence of oxygen, but becomes more soluble as conditions in the sediment and overlying water turn anoxic.   That means that when dissolved oxygen concentrations fall to the point where there is none at the sediment surface, the sediments are no longer a ‘sink’ for excess phosphorus, but become a ‘source’, releasing the stored nutrients back into the water.   From this point forwards, eutrophication in the lake becomes self-perpetuating and no amount of regulation alone will reverse this.

Better regulation now, on the other hand, might prevent the lake reaching this stage.  That, in turn, will protect the drinking water supply for the region, the economic benefits from the fishery and other ecosystem services. A survey of the local community revealed a willingness to pay an extra 27 Yuan a month for five years continuously in order to achieve this.  This is a small sum in absolute terms (27 Yuan is just over £3), but represents, on average, 1.7% of household income.   The economics of water quality improvement must look even more attractive to the regional government: if Ērhāi Hú crosses this tipping point then the investment in alternative water supplies, as was required in Kunming, will be equally expensive.  Looking at it from this perspective, applying a sensible ‘polluter pays’ policy now should be no more painful for the average resident than having to pay for new reservoirs to replace the resource on their doorstep.

The stretch of lakefront along which we cycled also had a steady trade in photographs, with photographers ready with diaphanous dresses for prospective models, and a number of ways for them to pose.  The girls in the photograph below posed, informally, on stones whilst friends photographed them using smartphones, but some photographers placed their models on the tops of jeeps or in hanging chairs, with an uninterrupted view of the lake behind. In their own way, they were valuing the broad scale panorama that the lake offered, just as we had enjoyed more local offerings during our lunch.  The challenge for the next decade, then, is to make the links between these valuations and the ecology of the lake, so that any price increases are recognised as sound investments in the future of Dàlī rather than as yet another form of negative taxation.

Women posing for photographs with Ērhāi Hú as a backdrop

References

Wang, H., Shi, Y., Kim, Y. & Kamata, T. (2015).  Economic value of water quality improvement by one grade level in Erhai Lake: a willingness-to-pay survey and a benefit-transfer study.   Frontiers of Economics in China 10: 168-199.

Wang, S., Zhang, L., Ni, L., Zhao, H., Jiao, L., Yang, S., Guo, L. & Shen, J. (2015). Ecological degeneration of Erhai Lake and prevention measures.  Environmental Earth Sciences74: 3839-3847.

Zhang, K., Dong, X., Yang, X., Kattel, G., Zhao, Y. & Wang, R. (2018).  Ecological shift and resilience in China’s lake systems during the last two centuries.  Global and Planetary Change165: 147-159.

 

Blooms from above

Saturday’s excursion saw us travelling to the southern end of the Kunming metro and joining a procession of locals trekking up the wooded slopes of the Xī Shān hills to the settlement of Lóng Mén (‘Dragon’s Gate’), which gave us some spectacular views over Diān Chí (Dian Lake) stretching away into the distance, After a lunch of fried noodles from one of the many takeaway stalls at Lóng Mén, we travelled back down to lake level by cable car, which gave us our second panoramic view of Cyanobacteria in three days.   The lake, China’s eighth largest, had a very conspicuous Cyanobacterial bloom that serves as the ‘yin’ to the Green Lake’s ‘yang’.

The environmental problems of Diān Chí are well known with an article in Newsweek describing it as the ‘ground zero of China’s toxic algae problem’.  The problems starts with Diān Chí’s location on a high plateau (1886 m above sea level) in Yunnan, which means that it has a relatively small catchment area relative to its size (40 km long, about 300 square kilometres area and with an average depth of 4.4 metres).   The city of Kunming sits at the north end of this lake and now has a population of over six million people.   For a long time, their untreated sewage was pumped directly into the lake, leading to high concentrations of phosphorus which, in turn, fertilised the lake water, allowing blooms of Microcystis aeruginosa to develop.   Many genera of Cyanobacteria, including Microcystis, produce potent toxins that attack the liver or nervous system, and which can cause skin rashes.

Unfortunately, the city of Kunming depended upon Diān Chí for its water supply in its past but now, due to this contamination, it has to rely upon reservoirs upstream of the city.  It has, according to the Newsweek article, invested $660 million dollars to reduce industrial pollutants, building sewage treatment works, intercepting polluted water and banning detergents containing phosphorus but that, as my photograph from the cable car shows, has had little effect.   There are two reasons for this.  The first of these is a reluctance to control fertiliser use in the productive agricultural areas to the west of the lake (China is not unique in this respect; a similar tardiness can be found in the West, where agriculture is a potent political lobby).  The second is that much of the phosphorus that was pumped into the lake in the past is still there, sitting in the sediments and being constantly recycled by the algae.  In small lakes it might be possible, albeit expensive, to dredge out this sediment but on a lake the size of Diān Chí this is an unimaginable prospect.

Another paper that I found online demonstrated a dramatic loss of higher plants and fish from Diān Chí. Since the 1950s, over half of all native higher plant species have been lost, along with 84 per cent of native fish.  Diān Chí also had a number of unique species, which evolved in this remote habitat, but 90 per cent of these, too, have been lost since the 1950s.  That is a catastrophe in biodiversity terms, but the collapse of the lake ecosystem also led to the loss of valuable commercial fisheries.  In the past, some of the fish and shellfish that we ate in local restaurants might have been bought from fishermen who worked the lake; now they have to be imported.

A view from the cable car over Diān Chí, with yellow rafts bearing reaeration apparatus visible on the lake surface.  The picture at the top of the lake shows one edge of the Cyanobacteria bloom, with clearer water along a channel flushed by inflow from a lagoon.

We can see, in other words, another interesting case study in competing ecosystem services emerging. We might imagine a time in the far past when there was a balance between the use of the lake as a supply of resources (drinking water, fish and shellfish, irrigation water) was not compromised by the use of the lake’s natural biogeochemical cycles to break down any waste products that flowed in from the catchment.   More likely, human and animal wastes would have been recycled more directly as manure for local agriculture so, again, some sort of equilibrium would have pertained.   Now, we see the ‘provisioning’ services compromised due to the overuse of the ‘regulating’ services and, at the same time, opportunities for ‘cultural’ services such as recreation are also much reduced.

Thinking more widely, what about the ecosystem services lost due to the construction of the new water supply reservoirs around Kunming?   But then, rather than end on an overly sanctimonious tone, to what extent have we in the West, ‘solved’ some of our own environmental problems in recent decades through the contraction of our own manufacturing industries in the face of competition from countries such as China?  \

A view south along Diān Chí with the far shore, 40 km away, just visible in the distance.

References

Liu, J., Luo, X., Zhang, N. & Wu, Y. (2016).  Phosphorus released from sediment of Dianchi Lake and its effect on growth of Microcystis aeruginosa.  Environmental Science and Pollution Research23: 16321-16328.

Wang, S., Wang, J., Li, M., Du, F., Yang, Y., Lassoie, J.P. & Hassan, M.Z. (2013).  Six decades of changes in vascular hydrophyte and fish species in three plateau lakes in Yunnan, China.  Biodiversity and Conservation222: 3197-3221.

Zhu, L., Wu, Y., Song, L. & Gan, N. (2014).  Ecological dynamics of toxic Microcystis spp. and microcystin-degrading bacteria in Dianchi Lake, China.  Applied and Environmental Microbiology80: 1874-1881.

Notes:many authors, Western and Chinese, refer to ‘Dianchi Lake’.  However, as ‘chí’ means ‘lake’, I have just referred to ‘Diān Chí’ throughout.  See “Lake lakelake lake” for more about this. “La Grande Assiette de Lac Léman”  describes a similar conflict between ecosystem services in Lake Geneva, albeit with more positive outcomes.

 

Reflections from a Green Lake

Our guest house in Kunming is a few hundred metres from the Green Lake, which sounds like an obvious magnet to someone with an interest in algae.   The name itself seems to embody the well-publicised problems of water pollution in this huge country and I walked down to the edge fully expecting to gather material for a post about extreme eutrophication.

This is not a post about extreme eutrophication.  That’s partly because it is not easy to get close enough to the water itself in order to look closely at the algae.  I did see some floating cyanobacterial scums amidst the duck weed and lotus plants, but I’m also not equipped with a high-power microscope whilst on my travels, so would not have been able to make a detailed diagnosis, even if I could have got a sample.   However, my feelings about the lake have changed over the four days that I have been here, and as I believe that travellers should prepared to be changed by what they encounter, I thought I should explain my change of heart.

Green lake is a small lake with a perimeter of about two kilometres and an area of about 15 hectares set in the middle of Kunming.   According to a book I have been reading, this whole area used to be part of the much larger Dianchi Lake (which will be the subject of a future post). However, during the Ming Dynasty, about 600 years ago, the area that we now know as Kunming was reclaimed, leaving Green Lake as a low-lying remnant.   At this time it was known as “Caihaizi”, the vegetable lake, perhaps because of the lotus plants that grew there.   If you want to apply a very basic measure of ‘naturalness’ to a lake, you could start by measuring the proportion of the perimeter that is artificial. In the case of Green Lake, the perimeter is 100 per cent artificial, unless you add in the islands and the causeways leading to these, in which case the proportion of artificial margins rises to 200 per cent or more.

A corner of Green Lake, showing duckweed blooms in the foreground and one of the causeways on the right.  The upper picture shows the lake with lotus plants in the foreground and Kunming rising up in the background. 

Yet the lake margins and the islands are thrumming with activity: joggers use the lake margin as a running track, badminton players set up nets between trees and thrash shuttlecocks back and forth whilst elderly men show off wiry torsos on the gym equipment.  Then there are the more quintessentially Chinese activities: groups of people practising Tai’chi and Quigong just a few metres from a dance class practising some moves.   On one of the islands about half a dozen different styles of dance are taking place, each moving to an amplified tune, all of which seem to bleed into one another.  We sat and ate cold noodles (local speciality: better than it sounds) in a café at one side until the noise drove us away.   A little further from here, on a bandstand on one of the causeways, a group of musicians played traditional instruments.   There were also pedalos and motorboats for hire on some of the sections of the lake, plus shops selling Yunnan tea and coffee and other souvenirs.

Cultural ecosystem services at Green Lake, Kunming.  The top image shows a group practising tai’chi and the bottom image shows a dance class nearby. 

After a few days here I am growing to love Green Lake.   It is a small ‘green lung’ set in the heart of a large, busy city to which local inhabitants, especially the elderly, seem to gravitate.  I have not written about ecosystem services – the benefits humankind derive from natural systems – for some time.  When I last touched on this subject, it was to consider the conflict between conservationist’s desire for naturalness and ‘cultural ecosystem services’ (see “More about ecosystem services”).   Green Lake seems to encapsulate this conflict very well: it is about as far from a ‘natural’ lake as it is possible to get yet, at the same time, it plays a role in the health and vitality of the local community partly as a result of the many modifications that have occurred over time.

To paraphrase jay-z, China has 99 [environmental] problems but Green Lake ain’t one.   I’ll come back to one of these in the next post but, meanwhile, I’m going to take one more stroll through the elaborately decorated gates at the entrance to the closest causeway and enjoy the pleasures of Green Lake for a final time before we move on.

A gateway to one of the Green Lake’s causeways in Kunming.

Reference

The book to which I refer is “Green Lake: Reflections from the Surface of China” by Hardy Wieting Jr (www.chinagreenlake.com), a conservationist who happened to be staying at the Lost Garden Guest House, near Green Lake, at the same time as us.

Algae in a stone forest

A change in location from the previous post: this one is being written on the roof terrace of a guest house in Kunming, in Yunnan Province, China, whilst sipping a cup of the local pu’er tea.   I’m in China with my family visiting my eldest son who works in Chengdu, a sprawling metropolis of 11 million people in Sichuan Province, and have escaped to the warmer climate and more sedate environs of Kunming (only 6 million people) for a few days.  We’ll then move on to Dali (a mere village, by comparison, with less than half a million people) before returning to Chengdu.

From Kunming we travelled about 120 km southeast to Shílín, the site of a strange Karst phenomenon known as the “stone forest”, a collection of upright pillars of limestone often with other limestone blocks perched precariously on top.   In geomorphological terms, we are looking at a limestone pavement on a huge scale, but with substantial erosion of the “grykes” (the gaps between the “clints”).   Geologically, it is a little more complicated than that, with the Permian limestone being later overlain by basalt which was subsequently eroded away to leave a red soil.  However, that is enough to give you some context for what follows.

The photograph at the top of the post gives you some idea of what the stone forest looks like, and also some idea of the crowds to be expected at mainstream tourist attractions in China.  At times, the mass of people and, in particular, the overlapping amplified commentaries from tour guides, dressed in the costumes of the local Sani ethnic minority, made the experience almost unbearable.  But then, as is often the case, you turn a corner, the hubbub dies away, and you are able to enjoy the ethereal landscapes almost undisturbed.  In our case, however, we turned a corner too many, found ourselves outside the officially-sanctioned tourist beat and were unceremoniously ejected by an officious security guard.

Once we had talked our way back into the park through the main entrance, using Ed’s Mandarin skills, the park was noticeably quieter.   Most of the organised tours squeeze the stone forest and a local cave network into the same trip so the morning crowds had been hustled back onto their coaches, and the whole experience in the park was much more pleasant.   Walking through the Major Stone Forest gives you an ants-eye experience of living in a limestone pavement habitat, with the clints towering above you and only occasional glimpses of sunshine.   The park authorities have provided a concrete path and steps to lead you through but it is, at times, an arduous trek with some narrow and low gaps through which to squeeze.   This, in turn, lets you get up close to the limestone and, in my case, gets the phycological antennae twitching …

The Major Stone Forest at Shílín from the inside.   The photo at the top of the post shows the Major Stone Forest from the main public viewing area.

The limestone from which the stone forest is made is largely slate-grey in colour, rather than the creamy beige that I normally associate with this rock.   Only after reading one of the interpretation boards in the park did the penny drop, and I realised that I, and thousands of other tourists, had each spent 130 RNB to stare at algae.   After my brush with officialdom in the morning I was not in the mood to scrape at the rocks to collect a sample but am guessing we are looking at the Cyanobacterium Gloeocapsa alpina or something similar (see “The mysteries of Clapham Junction …”).   We were visiting the park close to the end of the long dry season but for the next few months the climate here will be much damper, creating a more conducive environment for these microorganisms to grow.

A few of the rock faces, particularly those associated with seepages, had multicolour streaks, with the grey supplemented with pinks and greens.  The former may well be other Cyanobacteria (possibly Schizothrix) and the greens could be Apatococcus, Desmococcus or a relative (see “Little round green things …”).  There were also a few orange-red patches of Trentepohlia (see “Fake tans in the Yorkshire Dales”).   All of these are forms are familiar to me from the UK and, whilst it would be rash to assume that the species were identical to those I find back home, the genera are generally cosmopolitan, so some extrapolation can be permitted.

Algal crusts on rocks in the Major Stone Forest at Shílín, April 2019. The left hand image shows a mixture of Cyanobacteria and (possibly) green algae on a vertical surface associated with a seepage; the right hand image shows Heather photographing a growth of Trentepohlia nearby.

Trentepohlia growths inin the Major Stone Forest at Shílín, April 2019.  The picture frame spans about 10 centimetres. Photograph: Heather Kelly.

I did hunt around for some verification for these names but it is not possible to access Google Scholar in China without a VPN.  I am limited to whatever Bing throws up, and have not yet been able to find any papers on the algae of Shílín.  What I did find, during these searches, however, was an article about the world’s largest Haematococus farm, which is very close to here.   I’ve described Haematococcus in earlier posts (see “An encounter with a green alga that is red”) and mentioned that it was the source of the food colouring astaxanthin.   The combination of the limestone geology, warm weather and the huge market for food additives in China makes this possible.  Travelling in China with two vegetarians makes me realise that, even in this enormous, technocratic country, the market for natural products is growing.

 

 

How to make an ecosystem (2)

My most recent visit to Ennerdale and the River Ehen almost did not happen: unexpected overnight snowfall led to my wheels spinning on the Whinlatter Pass before I retraced my steps to Braithwaite and followed roads at lower altitudes around the outskirts of the fells.   Fieldwork in the morning took place amidst intermittent snow showers but, by the afternoon, it was dry if not quite as balmy as the visit I described in “Croasdale Beck in February”.   “Unseasonable”, I was reminded, is a two-edged term.

There was little incentive to linger with my arm in the agonisingly cold water, so this post is about some algae growing on dry land that caught my eye.   Amidst the gravel in a farmyard in Ennerdale Bridge I saw some dark brown leathery growths that I recognised straight away as the Cyanobacterium Nostoc commune (see “Nosing around for blue-green algae …”).  It looks rather nondescript, even slightly unsavoury, with the naked eye but, under the microscope, the rosary-like structure of the filaments suspended within a jelly-like matrix is revealed.  The slightly larger cells with thicker walls and lighter contents are the heterocysts, responsible for fixing nitrogen from the atmosphere (fulfilling the same function as the nodules on the roots of legumes).

A patch of Nostoc communein a farmyard in Ennerdale Bridge in April 2019.   The picture frame covers about 30 centimetres. 

Nostoc communefrom Ennerdale Bridge under the microscope.  Scale bar: 10 micrometres (= 100^thof a millimetre). 

This type of coarse, well-drained gravel is a good habitat for Nostoc and, once you know what you are looking for, it is a common sight on gravel driveways, usually to the annoyance of the owners.   If there is only a small amount, the best way to control it is simply to pick up the colonies and toss them onto the compost heap.  However, once it is established, this can be a big undertaking and many people are quite happy to tolerate some of this brown gunk on their driveways.   On the other hand, it can sometimes get out of hand and the consequences of not doing anything are well illustrated by the photograph below.  The Nostoc colonies have spread but these, in turn, have created a habitat into which first mosses and later grasses can establish.

This small farmyard on the edge of the Lake District contains, in short, the first stage of an ecological succession.  We could think of a gravel driveway as a mini-desert, as the copious Cumbrian rainfall will not be retained in the surface layers, making it hard for plants to survive.   However, if a tough organism such as Nostoc is able to establish itself, then this, in turn, will trap water and make the driveway more amenable to slightly more fussy organisms such as mosses.   As the moss and Nostoc grow together so, eventually, grasses are able to establish too.  Were there to be no interruption to this process then, eventually, decades later, we might even see trees growing on this driveway.

It is hard to imagine, but just about every type of terrestrial habitat started out, aeons ago, as a bare rock surface.  Various forms of physical weathering start the process of breaking this up allowing, over time, organisms such as Nostocto get a foothold and convert the virgin surface into a mature ecosystem (you can read about another example in “How to make an ecosystem”).   It may take centuries for this to happen in the natural world, so it is particularly fortuitous to see this human-assisted succession so well developed.  At some stage, I suspect, the owner will decide that enough is enough, and rake the gravel.  Meanwhile, however, we have a rare opportunity to reflect on the role that primitive micro-organisms play in shaping even the grandest of our natural habitats.

A lawn of Nostoc, moss and grass growing on a gravel driveway in Ennerdale Bridge, April 2019.  

Reference

Miles, J. & Walton, D.W.H. (1993).  Primary Succession on Land.  Special Publication of the British Ecological Society 12, Blackwell Scientific Publications, Oxford.