Head in the clouds: Vulnerability of cloud forests to climate change

When I first encountered an article on science daily written about 'cloud forests', I became instantly intrigued to find out what they were as images of fluffy cloud trees flashed through my mind.

Blue cloud topped trees- only believable in fantasy. 

However, after some investigating on the internet, I came across more and more articles describing cloud forest reserves and their vulnerability to climate change in the Age of the Anthropocene. Eureeeeka! A blog topic for this weeks post was discovered.

Tropical Montane cloud forests are among the most vulnerable terrestrial ecosystems in the face of climate change (Ponce- Reyes et al. 2012).  They have restricted climatic requirements and fragmented distributions. The forests support a range of endemic species and with such a unique biodiversity it is vital this ecosystem is protected.

A cloud forest is a tropical or sub-tropical evergreen forest characterised by a low level cloud cover. They also can be called mossy forests due their abundance of ground mosses and vegetation (UNEP, n/d). The forests gain their moisture from the low settling clouds surrounding them. The plants in the canopy have  adapted to be able to extract water directly from the clouds using 'horizontal precipitation'. 

Image of mountain cloud forests with the characteristic 

fluffy cloud top. 

These forests however are heavily dependent on local climates, due to the fact they only occur within narrow altitudinal limits and therefore are extremely vulnerable to climate change. Tropical montane cloud forests are distributed 23 degrees North to 25 degrees South. Important areas of cloud forest include Mexico, Central and South America, Indonesia, Philippines and the Caribbean. 

                                Locations of Tropical Montane Cloud forests (Aldrich et al. 1997)

'12% of Mexican cloud forest is protected, however it is still not known if reserves will ensure the persistence of this special ecosystem and the biodiversity it provides a habitat for' (Ponce- Reyes et al. 2012). In Mexico, cloud forests account for 1% of land cover, but support the highest concentration of plant and animal diversity of any other Mexican ecosystem. 30% of all flowering plants in these forests are endemic to just cloud forests and around 90% of Mexican cloud forests have already been cleared for agriculture, cropping, grazing and extraction of natural products. It is worrying that with climate change the conditions needed for these spectacular ecosystems to exist will become reduced, ultimately reducing the potential expansion rate of the cloud forests. What really stuck in my mind was the statistic that 'loss of cloud forest directly attritable to climate change would lead to the extinction of 37 vertebrates restricted to this region of forest'.  Clearly, immediate action is needed and it should be an urgent priority to extend the protected areas. 

Currently the world land trust (WLT) is working with the local conservation group 'ecologic Sierra Gorga' (GESG) to save as much of this threatened habitat as possible. 

To liven up the post and provide a real insight into the Mexican cloud forests and the anthropogenic threats posed to them, have a look at the following short video. It explains the reliance on these moist rich ecosystems for various types of agriculture and what this is causing to happen to the sensitive ecosystem. 

Score Board Update: Anthropocene 6 - 3 Biodiversity 

Have a Holly Jolly christmas...

First things first, Merry Christmas! Hope everyone had wonderful day. The blog post today is going to be christmassy themed to hopefully keep you all in the spirit of christmas, at least till the new year when coursework deadlines will be deeming. To begin to set the mood, before you read on and discover the wonders of christmas holly (Ilex aquifolium) give the song a listen and dance around. Christmas day itself may have passed but the christmas holidays are still upon us.

Now we have you all in the mood, let me introduce today's topic 'English Holly' or sometimes known as 'Christmas Holly'. I did not realise that this seemingly harmless festive tradition is also a problematic invasive species in some areas such as in America and Pacific Northwest. Ilex aquifolium is a broad leaf evergreen shrub that can grow from 5-18 metres high. With its pretty waxy leaves and red berries, it has become, in Britain, to epitomise the essence of christmas. 

Image. English Holly with its poisonous red berries on the female plant. 

The holly is shade tolerant and highly competitive with other native understory plants (Boersma et al. 2006). This particular holly has escaped into forested areas where it grows in shade or sun on well drained soils. Due to the way it can grow vegetatively or by seed, it is resilient to changes in climate. It is particularly detrimental to native plants as it is a water hog, preventing sufficient water for the surrounding vegetation. With climate change, English Holly is going to be affected much like any other species on the Earth. In the IPCC 4th report, it stated that ' English Holly would see a poleward shift of the northern margin due to increasing winter temperatures' `(WWF, n/d). The same shifting is also predicted to occur with European Mistletoe (Viscum album) which is gaining altitude in response to climate change. The study reveals that the plant has climbed 656 feet in the last hundred years (National Geographic, 2010). 

Till next time, eat, drink and be merry!

Eutrophication Looming...

Freshwater habitats are disproportionally diverse compared to other ecosystems, with them only covering 1% of the world surface yet providing habitat for over 25% of described vertebrates (Kipping, 2008). It has been estimated by the ICUN that there are around 27,400 freshwater species including fish, crabs, dragonflies and plants. With such a vast biodiversity, freshwater ecosystems provide many important goods and services not only to ecology but to humans also, including building materials and  flood and erosion control. Many of the world's poorest neighbourhoods rely solely on these ecosystems. 

Since the industrial revolution, many anthropogenic activities have caused alterations in the structure and functioning of freshwater environments (Millbrook, 2009). By increasing demands of aquatic environments, eutrophication has lead to undesirable changes in freshwater biodiversity (Smith et al. 1999). Changes in land use, including land clearing for agriculture, forestry, animal husbandry and urbanisation has caused an increase in the available limiting nutrients, nitrogen and phosphorous in global biochemical cycles, that have been polluting lakes and streams worldwide (Vitousek et al. 1997). This surplus of nitrogen in terrestrial soils can move easily from land to surface water, migrating into groundwaters, increasing the toxicity (Nolan et al. 1997). With increasing human population densities, the increasing combustion of fossil fuels has been causing additional atmospheric nitrogen to enter water sources, increasing nutrient levels in many water bodies that are located near heavily populated areas. To understand how freshwater biodiversity is severely threatened by nutrient loading, it becomes vital to understand firstly, what is meant by this word 'eutrophication'. 

'Eutrophication is the process by which water bodies are made more eutrophic through an increase in their nutrient supply. This can choke rivers, lakes and other waterways by excess algae growth which has been simulated by fertilisers and poor disposal of human sewage' (Smith et al. 1999). 

Eutrophication influences the production of blue-green algae (cyanobacteria) and the growth of vascular plants in freshwater ecosystems which can effect light penetration into water bodies. The impacts are much more wide reaching than plant growth alone. Eutrophication also causes degradation of such water bodies resulting in a loss of species. (Postel and Carpenter, 1996). 

Blue-green algae (a easily observable green layer covering a fresh water source). 

In recent decades, eutrophication has been highlighted as one of the most serious environmental problems facing water managers. In Europe, this is especially seen as a highly destructive problem, hence why the European Water Framework Directive has allocated it as a important issue on their agenda (Sandergaard et al. 2007). Billions has already been invested to curb this issue by improved water treatment, however, despite this, eutrophication still remains a devastating problem in many areas. Saandergaard et al. (2007) portrays how internal mechanisms, both chemical and biological can prevent lake recovery. Such internal mechanisms include, internal loading from lake sediments (Marsden, 1989) and the 'development of zooplanktivorous and bethivorous fish in eutrophic lakes which reduces the top down control of zooplankton and phytoplankton' (Shapiro and Wright, 1984). 

Whether there is success or not from eutrophication conservation strategies, it has been certified that permanent effects of restoration can only be achieved if external nutrient loading is reduced sufficiently to low levels. Millbrook (2009) explains how

'historically environmental management strategies of freshwater systems have focused on reducing phosphorus pollution. While this has minimised freshwater algae blooms, it passed a great deal of nitrogen pollution to coastal systems'. 

With eutrophication a GLOBAL concern (affecting not only freshwater ecosystems, but coastal and marine systems),  it is becoming ever more important to acknowledge reliable management strategies. With the numbers of human population sporadically rising- euthrophication continually poses a greater threat to one of the world's most vulnerable ecosystem!

Score board update: Anthropocene 5 - 3 Biodiversity 

A melting world? Indirect impacts of sea ice loss

With the last post concentrated on the direct effects of sea ice loss in the Arctic, this post will look again at tithe phenomena of sea ice, but with a particular focus on the indirect impacts of Arctic sea ice disappearance. Below is a short video which aims to portray ice minimum volume from 1979 to 2013.

Sea ice loss may influence ecological dynamics indirectly through effects on species movements and disease transmission causing species to become more vulnerable. Arctic populations isolated when an ice free season occurs in the Arctic, the declining presence of sea ice could reduce inter-island migration. With the lengthening of the ice free season, genetic isolation among populations is encouraged (Post et al. 2013). For some species, sea ice can act as a barrier to dispersal, due to the lengthening of the sea ice free season will increase population mixing, reducing genetic differentiation. This impending loss of sea ice will increase contact among closely related series for which it currently acts as a mixing barrier. Hybridisation is likely to become increasingly common. Polar bears and grizzly bears may be the result of increasing inland presence of polar bears as a result of prolonged ice free seasons (Hoflinger, 2013).  In Canada, the projected decrease in sea ice cover with Arctic warming, will increase contact between Eastern and Western Arctic species.

Image of a 'pizzly' the grizzly-polar bear hybrid. 

A second indirect impact is changes that occur in animal behaviour as a result of sea ice loss. In the Canadian Arctic, later ice seasons and increased shipping traffic due to the lengthened ice free seasons could prevent migration of the Dolphin and Caribou (Poole et al. 2010). It is widely understood by ecologists that migration can decrease the likelihood of parasitism. The changes in ice formation within the Arctic could change the amount of parasite loads among the Dolphin migration herds. However, sea ice loss is not always looked on negatively, with the reduction of sea ice promotion migration hence preventing disease epidemics where the sea ice provides a corridor for pathogen transmission (Post et al. 2013).

Image. Caribou migration route in the Arctic. 

Sea ice loss also effects terrestrial ecosystems including especially, land adjacent to the sea ice. Arctic warming, delayed freeze season and sea ice loss will promote permafrost warming increasing terrestrial primary productivity. There has been increases in the abundance and cover of shrubs occurring across the Arctic. 

A recent report by the Arctic council and the National Oceanic and Atmospheric administration (2013) shows evidence of a shift to a new warmer, greener state. The major findings of this report include:

1) Vegetation in the Arctic is greener with a longer growing season. 

2) Wildlife and large land mammal populations continued declining trends with Caribou having unusually low numbers. 

3) Sea ice extent in September 2013 was the sixth lowest since observations began in 1979. 

4) Northward migration into the Arctic of fish such as Atlantic Mackerel and Atlantic Cod. 

This report shows that recently there has been increased concerns over this region of sea ice loss. With the academic community trying to understand how extensive the impacts of sea ice loss are. With conditions changing for many species in the Arctic, it is important to note that sea ice decline is not itself solely responsible for many individual species decline, however it plays a role with a combination of other factors. Declining sea ice is not uniform and therefore individual species responses will remain varied (Mueter and Litzow, 2007).

As we can see from the last two posts, sea ice loss can have both negative and positive effects on the ecological diversity of the Arctic. Keep your eyes peeled for the next post which will offer some insight into a completely different area of global biodiversity, one that is extremely threatened- freshwater biodiversity.


Score Board Update.

Anthropocene 4 - 3 Biodiversity 

Biodiversity in the cryosphere

As one of Earth's major biomes, the Cryosphere (taken from the Greek 'krios' meaning cold, frost or ice) is extremely important to consider when trying to understand global biodiversity. The Cryosphere encompasses those parts of the world which are frozen including, ice sheets, glaciers, frozen rivers, lakes, sea ice, permafrost and ice shelves. Today, I am focusing on the importance of sea ice to Arctic biodiversity after being fascinated by the paper published from Post et al (2013) introduced to me by my global environmental change lecture on the 6th December. With it being published only a few months ago, I decided to read the full paper and became instantly intrigued by polar biodiversity.

Sea ice compromises unique ecosystems in, on and under the ice. This habitat is critical for many species including vertebrates, diatoms, also terrestrial productivity and aquatic diversity. With 80% of the tundra in the Arctic lying within 100km of an sea ice covered ocean, Arctic ice loss driven from amplification Arctic warming is vital for ecological dynamics in this area (Post et al. 2013). Arctic amplification is the melting of ice due to a positive feedback albedo system. Ice has a high albedo therefore reflecting sunlight keeping the poles cool. However through ice melt, more of the Arctic ocean becomes exposed and due to oceans being darker they have a much lower albedo. This means they absorb heat warming the oceans and the atmosphere. As the oceans absorb heat, they also have to release this increased heat to enable the sea ice to form for the next year. Due to this feedback, the more ice loss the longer it takes for oceans to release the heat it has absorbed and therefore sea ice formation gets delayed. This can have affects for semi-aquatic species such as polar bears which use the sea ice for reproduction ground and for resting during long migration routes.

With anthropogenic warming Arctic sea ice extent has slowly been declining.

Source. A) Graph showing the declining annual minimum Arctic sea ice extent from 1979 to 2012. Although,  there is seasonal variability the overarching trend is a decline. B/C) Two maps showing the percentage concentration loss of sea ice with the scale bar showing -5% to 5% change. B is from 1979-1999 and C from 2000 -2011. 


The trend seen in the maps is showing percentage loss, especially around the edges of the sea ice, due to warming oceans.

The direct effects of Arctic sea ice loss

1. Primary producers depend on the sea ice habitat, underpinning the whole Arctic marine food web.

- With the loss of sea ice, this is a loss of habitat for algae and phytoplankton.  The timing of the algae bloom which is ultimately driven by light penetrating the ice when it is thin enough, is vital for the reproduction of zooplankton grazers. Disruption of this timing due to accelerated ice melt has created mismatches for zooplankton production timing and the consumers up the food chain.
- Earlier phytoplankton blooms can shorten the length for primary productivity consequently affecting the zooplankton production and the Arctic cod species that feed on them (Post et al. 2013).

2. With ice melt comes increasing freshness of the Arctic ocean.
- This reduces the nutrient availability for phytoplankton which limits their productivity despite increased solar penetration through ice thinning.

3. As previously touched upon, vertebrate species such as polar bears require sea ice for reproduction and resting and therefore they are directly implicated by sea ice thinning. One species also effected is the ringed seal (Gohring, 2012). More than two thirds of the Arctic has been estimated to have insufficient snow cover for ringed seals to reproduce challenging their whole survival. A ringed seal is currently under consideration for the threatened species list due to the way it builds caves to rear its offspring in snow drifts on sea ice (NOAA, 2013).  (Hezel et al. 2012) estimated that snow drifts must be at least 20cm deep to support the caves. As sea ice disappears, there is no where for the snow to pile up, ultimately declining the area where the seals can reproduce. What is also worrying is that with earlier snow melt year on year, the caves will melt also much earlier, leaving the young vulnerable to the outside conditions and predators.

Next week, I will be continuing the polar theme by exploring the indirect impacts of sea ice loss in the Arctic so keep those eyes peeled. Only two weeks till christmas!!

Score Board Update: Anthropocene 4 - 2 Biodiversity. 

Discovery of new species everyday: Is biodiversity increasing?

Moving away from the ocean focus from the past two weeks, todays post explores a recent article by the BBC about the identification of a new wild cat in Brazil by Coles (2013).

Everyday I look on Nature and there is an article about a new species being discovered. These new species are found in a range of locations from Burma to closer to home in the United Kingdom. With new species being discovered everyday, is it possible to make the judgement that biodiversity is possibly increasing on local scales around the world?

Check out the Coles (2013) article and make up your own judgements. It is important to note that we do not know everything about the natural world and therefore to make all encompassing conclusions about global biodiversity, is extremely difficult.  These conclusions are strictly based on the knowledge we do have while accepting the unknown.

Articles to check out:

New species of Hammerhead shark discovered off Carolina coast (Kenniff, 2013)

Spectacular New Species Found in the Lost World (Dell'Amore, 2013).

New Species of 'Skeleton Shrimp' discovered (Vincent, 2013).

Score Board Update: Anthropocene 3 - 2 Biodiversity 

Coral Catastrophe?

Being an ecology enthusiast with a particular fondness for corals, todays post is one of my favourites so far. We all acknowledge that coral reef ecosystems are extremely important to the health of the oceans. While they cover only 1% of the oceans, it is estimated that one quarter of all marine biodiversity spends, at least part of their life on a coral reef. When corals are mentioned most people think of tropical waters and an instant picture of the Great Barrier Reef pops into mind. To me the term 'coral' automatically conjures up brightly coloured images present in the Pixar film, Finding Nemo.

However, as the NOAA state shallow water corals are only one type. There are cold water corals and deep sea corals that have limited light producing soft corals. 

What are corals?

The Oxford English Dictionary defines corals as ' hard stony substance secreted by certain marine coelenterates as an external skeleton, typically forming large reefs in warm seas'. 

Corals are invertebrate animals belonging to a group called the Cnidaria. They can exhibit a wide range of colours, shapes and come in all sizes. Each coral is made up of hermatypic polyps and most live in colonies. A coral colony can grow to be very large indeed. The hermatypic polyps produce calcium carbonate to form calyx (NOAA, 2011). The calcium carbonate adds to the coral skeleton forming the beginnings of the coral structure. Corals develop slowly over millions of years, today the corals you see have been growing for around 50 million years. To date there are around 800 known species of hard coral and more being discovered, just as new species of marine animals are being found in the most remote ocean locations every day. 

Source. Coral forming diagram.

Where are corals found?

Coral reefs are found throughout the oceans, from deep, cold waters to the shallow tropical waters of the Indian Ocean. Tropical reefs extend from 30 degrees North and South of the equator. However, cold corals can also be found in places closer to home such as off the West coast of Scotland and Ireland. Cold water reefs have also been found in the Mediterranean. 

There are various factors that cause the pattern of coral reefs throughout the world. 

These include:

The role of ocean temperature

The effects of emersion

Bathymetry

Levels of sedimentation



Types of Coral Reef

• Fringing Reef: most common type of coral reef located close to land. 

• Barrier Reef: looks like a fringing reef, however, it is located further away from the shore. They are separated from the shore by a band of water.

• Atoll: large ring shaped reef, which create a lagoon in the middle. 

Anthropogenic threats to coral reefs
Corals are ecosystems that have been developing for years, and in this time have been subjected to natural change. The worry now is that with increasing human stresses, corals may not be able to cope.   WWF (2010) states that already 'one quarter of coral reefs are subjected to damage beyond repair, with another two thirds under threat'. With reef building corals representing a critical component for marine biodiversity, it becomes important to conserve these ecosystems in order to conserve the species that use coral environments (Huang and Roy, 2013). 



Destructive fishing practices: Blast, dynamic fishing and bottom trawling are types of fishing practices that cause devastation to sensitive coral reefs. Bottom trawling has been widespreadsince the 1980s. The large rubber tires on the nets can damage the coral structures. Dynamic fishing is  where explosives are set off underwater destroying coral. This has been particularly a problem in South East Asia (Cadwell and Fox, 2006). 



Pollution: Urban and industrial waste being released into the oceans which are poisoning the reefs.  Pollutants increase the amount of nitrogen in the waters causing an overgrowth of algae, which can smother the reefs, concealing them from sunlight which the polyps need to survive (McManus, 2000).



Sedimentation: Anthropogenic coastal construction, mining, logging and tourism developments can cause erosion. This erosion causes increased levels of sediment being produced. Sediment covers coral, almost suffocating it and causing the corals to produce a protective mucus (MES, 2002). This process takes incredible amounts of energy and if corals are overworked they can die. 



Ocean acidification: As mentioned in my previous post, marine environments are particularly threatened by climate change and the increasing pH of ocean waters. Since the beginning of the industrial revolution, the oceans have been absorbing increasing amounts of excess carbon dioxide. With ocean acidification, corals cannot absorb the calcium carbonate needed to maintain their structures and therefore the reef will dissolve (SCOR, 2009). 



        
Ocean acidification effects on coral reefs. 


Global warming and coral bleaching: In the Anthropocene, global warming is a known threat to many ecosystems. It occurs because carbon dioxide and other greenhouse gases cause a blanket, preventing heat from the sun to escape, warming the atmosphere. Ocean warming is extremely devastating to coral biodiversity, which is sensitive to changes in temperature. If oceans stay warm for several weeks, zooplankton leave the corals, turning them white in the process, because it is the zooplankton that gives corals their unique colours. NOAA (2013) discussed how in 2005, the USA lost half of its coral reefs in the Caribbean in only one year due to a huge coral bleaching disaster. 



       
Coral Bleaching: showing the distinctive white coral. 



However, a recent study showed it is not all bad news. Elevated nitrogen and phosphorous at a study site in Florida Keys from 2009-2012, showed coral bleaching. What this study also noted was that once the injection of pollutants ceased, the corals became able to recover and in a surprisingly short period of time (PhysOrg, 2013). 


There are other threats to corals, however I have rambled on too much already. I hope you enjoy this post and it provides a insight into the marine biome and the anthropogenic impacts of coral ecosystems. Being a corals fanatic, I find it extremely worrying that humans can be having such disastrous effects to one of the world's most beautiful environments. I, for one, want to be able to dive  and explore these unique ecosystems, enjoy their bright colours and extraordinary patterns and it would be devastating if these environments were not there for people to enjoy. 

Score board update: Anthropocene 3 - 1 Biodiversity 

Oceans- What will the future hold?

In previous posts I have concentrated on mainly terrestrial biodiversity (however not on purpose). Today I take a swim with the fishes to investigate one of Earth's most interesting biomes- the ocean.

'The ocean covers nearly three quarters of the Earth's surface, provides about half of the oxygen we breathe and feeds billions of people every year' (Le Roux, 2013). 

The oceans have been protecting the Earth from the worst effects of human induced climate change for years by absorbing excess carbon dioxide (Bijma et al. 2013). This absorption, however, is having a negative effect driving the oceans into an acidic state. Along side this acidification, ocean warming is having grave impacts on the structure of many marine ecosystems. Bijma et al.(2013) coined ocean warming, acidification and deoxygenation the 'deadly trio' of anthropogenic impacts that are causing  accelerated loss of marine populations (Worm et al. 2006). Since the industrial revolution the world's oceans have become 26% more acidic and will continue to force oceans into a acidified state at an unprecedented rate.

Ocean acidification is the reduction in the pH of the ocean waters by the uptake of carbon dioxide from the Earth's atmosphere. It can also be caused by chemical pollution into the oceans. The carbon dioxide dissolves in the seawater generating changes in seawater chemistry. The addition of carbon dioxide increases the concentration of bicarbonate ions and carbonate ions which, consequently lowers the pH making oceans more acidic. For a beginners insight into ocean acidification take a look at the below flow chart, showing the changes in chemistry from slight alkaline to acidified seawater. 

Beginners guide to ocean acidification.

Many recent reports, have discussed how ocean change may be faster than any time in the last 300 million years, predicting that by 2100 there will have been a 170% increase in ocean acidity. But is it all doom and gloom for oceans? There has in fact,  been scientists that have discussed how marine species could survive and even thrive (seagrass) under ocean acidification and warming (McGrath, 2013). 

What environmental scientists are most worried about is the effect of the 'deadly trio' on corals. In the Great Barrier Reef half of the coral cover has been lost over the past 27 years. There have also been dramatic coral bleaching events in 1998 and 2002 due to anthropogenic ocean warming. In the Southern Ocean, we can unfortunately already see corrosion of pteropods (sea snails) shells. In my next post, I aim to expand on corals in more detail, focusing on the threats posed by the anthropocene to these highly sensitive environments. 

Coral Disaster: Great Barrier Reef coral bleaching. Source. 

With a carbon release of around 30 gigatonnes of carbon dioxide a year, it is no surprise that academics are worried about a major ocean extinction. As I touched upon in my previous post a sixth mass extinction' is a upcoming worry. However, speculative this theory may be, oceans are one of the biomes which are most vulnerable to a huge biodiversity decline. With changing ocean conditions, many species could possibly find themselves in unsuitable environments, especially in oxygen poor "dead zones"(Le Roux, 2013). 

What will the future hold for the oceans? Will there be a biodiversity loss in one of the worlds most diverse environments? Keep your eyes peeled for my next post which will look at the threats posed to corals.

Score Board Update. 

Anthropocene 2- 1 Biodiversity.

City Biodiversity and the development of 'Green Urbanism'

As previously suggested we have entered a new geological epoch called the ‘Anthropocene’ where the cumulative impacts of billions of people are being experienced. The impacts are so extreme that we are now disrupting this steady state life system through climate change, toxic air pollution, biodiversity collapse and social inequality (Partington, 2013) Recently, there has been a lot of  discussion in scientific literature surrounding biodiversity and urbanization, especially relating to city biodiversity. Urbanisation is the physical growth of urban areas as a result of global change. With a booming human population, city biodiversity is set to become a major factor in our increasingly interconnected world. The Convention on Biological Diversity (2011) stated that by 2050, almost 3 billion additional people will inhabit the world’s cities and the world will have undergone the largest and fastest period of urban expansion in all of human history. A recent estimate reveals that the area directly impacted by new urban infrastructure within the next 40 years will roughly cover an area the size of Mongolia, with obvious impacts on the natural habitat. Consequently, urban growth will impact the provision of many ecosystem services and the demands of cities will reshape most rural landscapes in the coming decades.

Map showing the transport links of humanity and the interconnectivity of the globe.

One way urbanisation can cause disturbance to biodiversity is through habitat loss (Czech et al. 2000). It is often cited as the primary cause of species endangerment in the United States. As can be seen in the table below, urbanisation caused 275 endangered species in United States and Puerto Rico (Czech et al. 2000). The only human impact that tops urban development is non-native species disturbance. Czech (2004) states that urbanisation is one type of habitat loss and that this anthropogenic implication can transform the “economy of nature” to the human economy. In some cases of habitat loss, natural capital is simply cleared away to make room for human economic infrastructure and enterprises. 

It is not just cities that will have an increasing human population, infact most of the urban expansion is predicted to occur in medium to small urban areas of low economic capacity. Since urbanisation is changing the nature of our planet, preserving biodiversity on this urban world requires going well beyond the traditional conservation approaches of protecting and restoring what we think of as “natural ecosystems,” and trying to infuse such elements in the design of urban spaces (Convention on Biological Diversity Report, 2011). The report also states that 

‘cities already represent a new class of ecosystems shaped by the dynamic interactions between ecological and social systems. As we project the spread of these ecosystems across the globe, we must become more proactive in trying not only to preserve components of earlier ecosystems that they displace, but in imagining and building entirely new kinds of ecosystems that allow for a reconciliation between human development and biodiversity’.

It is refreshing to hear that people are accepting urbanisation and its affect on biodiversity, including trying to think creatively about new spaces in the city to encourage species diversity. While we know that urbanisation, through habitat loss, can displace many species it becomes vital to understand that some species have infact evolved adaptive responses to thrive under urban pressures. Some endangered species find suitable habitats in urban ecosystems, especially with innovations such as rooftop gardens and vertical forests being established. Anthropogenic technological advancements such as supplementary watering systems, have the potential to offer novel habitats and niches for species quite different from those in more natural ecosystems (McKinney, 2002). 

However, just because urbanisation poses a threat to biodiversity, it does not mean that cities cannot sustain diverse ecology. In fact many cities have high species richness and several are located within 'biodiversity hotspots'. Such cities include, Berlin, Brussels, Chicago, Frankfurt, Helsinki, Mexico City, Sao Paulo, Singapore and Vienna. The assessment of Cities and Biodiversity Outlook (CBO) argues that cities should facilitate for a rich biodiversity and look after the multitude of ecosystem services, such a rich biodiversity can provide, rather than being the culprit of enormous ecological footprints. With such a diverse ecology, cities have the potential to mitigate the effects of climate change. The Japanese district of Yokohama, which emitted almost 20 million tonnes of carbon dioxide in 2007, has now recognised the importance of biodiversity in stabilising the local climate. Innovations such as green roof tops and walls have been developed to act as carbon sinks (SRC, n/d). It is now being acknowledged that it is the responsibility of architects to develop 'green' cities, including creating an integrated holistic approach to create sustainable urban infrastructure. 

To create sustainable cities, developments such as green corridors along highways, railways or bikeways have been planned. There are many new and exciting ways in which architecture and biodiversity are becoming linked. Edwards (2010) explains how the political focus on global warming has tended to reduce the importance of architects in protecting biodiversity. However, the impacts that architecture has upon ecosystems, including decisions regarding building materials, sourcing the materials, rehabilitation of existing structures, decisions regarding walls, roofs and landscape, are enormous. Architects can see this as an opportunity to connect architecture to nature. An example of this is by Edwin Lutyens, who created bat and owl boxes within roofs, making them part of a more ecological architecture (Edwards, 2010). Although architecture does not traditionally concern itself with such matters, the growth of sustainability focused global narratives and EU regulation exposes building design and construction to the close scrutiny of the biodiversity movement. Some architects have already started to fill in the gap. The 'cradle to cradle' idea owes much to an understanding of ecological systems, taking principles from nature and applying them to buildings. It is a holistic framework that aims to create systems that are efficient and also essentially waste free. Similarly the 'biomimicry' design movement and such innovations as bioclimatic skyscrapers and green urbanism promoted over a decade ago, have a clear commitment to addressing biodiversity (UICN, 2013). Ken Yeang, a Malaysian architect and ecologist inverted the high-rise to be designed as a 'city-in-the-sky'. The first example of this was the National Library Singapore (2005). The building features large 40m high 'public realms-in-the sky' in the form of two landscaped sky court gardens.  

Urban design provides the framework for the effective use of land, allowing greenery and biodiversity to penetrate the city. With good design, urban areas can provide opportunities, not merely threats, to ecological diversity. These corridors of biodiversity, including urban wetlands, allotment gardens, botanic gardens, parks and roadside trees can be linked into a network, creating a 'green' city. Architects also have a key role to play to reduce energy consumption. The choice between steel, concrete, masonry or timber construction is complex from an energy point of view (UICN, 2013). However, society is trying to gain a better understanding of green construction. 

Two examples, where the connections between urbanisation and biodiversity are being acknowledged are London Heathrow and Mayesbrook Park. London Heathrow has recently completed a new survey of the biodiversity in its 30 hectare site. They found that the airport offered a range of habitats including grassland, and other landscaped habitats. Within these habitats Heathrow was home to a multitude of rare species of bats, spiders and insects. In total it discovered 129 species of spider and 304 species of beetles (Travel News UK, 2013). This goes to prove that not all urbanized areas threaten species biodiversity, in fact, if the design is incorporated with green infrastructure in mind, species can actually flourish in man made habitats. London's Mayesbrook Park, in urban East London, has transformed a rundown 45 hectare park into a showcase of public green space. The project involved creating a new floodplain that can naturally store floodwater, planting new shrubs and trees to enhance habitats for species encouraging increased biodiversity. This £3.8 million project clearly demonstrates how restoration of biodiversity in cities, can also provide other knock on effects such as climate change adaptation and enhance the well being of people living in the city (Convention of Biological Diversity, 2011). 

Mayesbrook Park,  East London

Overall, cities can provide a unique habitat, one that can produce a rich biodiversity. With an increasing urban population, 'green' urbanism is key to producing sustainable cities in the future. It is vital that governments and planning agencies take into account the benefits that new urban spaces can provide to not only biodiversity but also to localised climate change and air pollution. With urban habitats being surprisingly diverse, such richness of habitats also results in the generation of multiple ecosystem services, which can contribute significantly to human well being. With growing awareness of the value of biodiversity and ecosystem services cities with rich native biodiversity should ensure that their biodiversity is conserved. I will leave you with the words of Professor Thomas Elmqvist, scientific editor of the assessment at SRC, 'cities need to learn how to better protect and enhance biodiversity because there is a direct relationship between biodiversity and many ecosystem services'. 

Score Board Update: Anthropocene 1- 1 Biodiversity 

Biodiversity and urbanisation- Introduction

Hi all,  hope everyone is having a good start to their reading week. I am currently in the process of writing my next blog post which will focus on biodiversity and urbanisation. Personally, I find this topic extremely interesting (hence why it seems to be taking so much time to collaborate my many pages of reading notes. I think I went slightly overboard on the whole reading around the topic!). Are you excited yet? Well if the thought of biodiversity makes you yawn with boredom... here is a short video to get you anticipating tomorrows big reveal.

The key questions that I aim to explore in tomorrows post are:

1) What is urbanisation?
2) Do cities have rich or poor biodiversity?
3) How is urbanisation harmful to biodiversity?
4) Is it possible for buildings to restore nature?
5) Can increased urbanisation lead to increased invasive species?
6) Are new schemes being adopted to conserve biodiversity in the age of unregulated urban sprawl?

Enjoy and keep an eye out tomorrow!

Sixth mass extinction just around the corner?

Following on from the videos I posted last week, my post today is going to focus on a recent paper by Barnosky et al. (2011).  Barnosky provides a detailed background to previous mass extinctions and also  focuses on arguments surrounding the possibility of a sixth mass extinction.

What is a mass extinction?

The answer lies in the past. Palaeontologists characterise a mass extinction as a short geological period in Earth's history where more than 75% of estimated species become extinct (Jablonski, 1994).  This type of extinction has only happened 5 times in the past 540 million years (Barnosky et al. 2011). The 5 mass extinctions occurred at the end of the Ordovician, Devonian, Permian, Triassic and Cretaceous periods. Will the anthropocene hold the next mass extinction?

Biodiversity of the planet over time, showing the five mass extinctions in history.
Graph adapted from Wilson (1992)

Why do we care about past extinctions?

Scientists are interested in past extinctions because they provide a key to the future. The most famous species extinction was the Cretaceous- Tertiary which occurred 65 million years ago. This is the extinction that is famed for the death of the dinosaurs. One hypothesis for this decline was climatic cooling causing a reduction in hospitable habitats (this is the worry for current global warming). The Permian extinction (248 million years ago) also causes scientists to quake in their boots due to being caused mainly by global environmental change, including methane release from the sea floor, increased sea level and a shift in ocean circulation (Eldredge, 2011). The main concern is that history will repeat itself? Increasingly, academics are recognising contemporary species extinctions as part of an overarching 'sixth mass extinction'. Anthropogenic influences such as habitat fragmentation, disruption by invasive species and changing global climate all directly contribute to the decline of biodiversity. Scientists are now worried that the Earth will, in a few centuries, be under threat from major species decline.

Before we can come to any sort of conclusions, it remains vital to establish the current situation within the context of  previous mass extinctions. There have been many landmark studies that have told of modern extinction rates an order of magnitude higher than than previous extinction rates (Doubleday, 1992; May et al. 1995). The below chart explores the extinction magnitudes of IUCN assessed taxa in comparison to the 75% benchmark (International Union of Conservation Red List, 2010).  The black icons add the species that are currently 'threatened' species to those that have been extinct for over the past 500 years. Therefore, we can see that all species are threatened in the age of the anthropocene. Groupings such as mammals, birds and amphibians, which have had historically the lowest percentages of species extinctions, nowadays have the highest numbers of endangered and threatened species. Could these species be susceptible to catastrophic extinctions? The current numbers show the sixth mass extinction is looming quite far away, however anthropogenic activities are causing more and more species to become increasingly threatened. Barnosky et al. (2011) suggests that if all 'threatened' species disappeared we would be half way towards a possible anthropocene mass extinction.

Extinction magnitudes of IUCN assessed taxa (2010)

It is not just terrestrial species that are vulnerable, marine species are particularly susceptible to mass extinction. At least 830 marine species have been classified as critically endangered, endangered or vulnerable. Assessments for marine species are lagging behind those for terrestrial species. However, the IUCN aimed to have 20,000 marine species assessed by 2012. It is important to understand that the past drivers of extinction in the oceans are the same as the current threats  (as can be seen in the chart below).  Marine scientists that released the State of the Ocean 2013 report on 3rd October 2013, gave a warning stating 'we are entering an unknown territory of marine ecosystem change, and exposing organisms to intolerable evolutionary pressure. The next mass extinction event may have already begun'. The report explains how the ocean is the world's largest carbon sink and the increasing carbon dioxide levels are creating a 'deadly trio of impacts' including ocean acidification, ocean warming and deoxygenation all of which are threatening marine biodiversity. If you want to know more about this , check out The AnthropoSea, a blog dedicated to investigating the 'deadly trio' and its threat to marine biodiversity. 

What is the situation today? 

Today, the rapidly changing atmospheric conditions and warming of above average interglacial temperatures cause species to become vulnerable. With rising carbon dioxide levels, habitat destruction, pollution, overfishing, over hunting and invasive species, the world now has more ecological stressors than many species have ever experienced before. 

Species extinctions rising with increasing human populations.

The worrying question is how will this affect the already threatened species? It seems quite plausible that if humanity carries on living in the same way, it will not be long before the 'sixth mass extinction' is just around the corner.  It is encouraging that there is still much of Earth's biodiversity that can be saved. However, it is daunting that in order to save such species there must be rapid reversal of escalating threats. How realistic is this? 

While I was researching for this blog post I came across a very interesting short film that had just been released called the 'Last Hours'. The film had been produced for presentation at COP21 (the 21st session of the Conference of the parties to the UNFCCC expected to take place in 2015). The film maker was Thom Hardmann, an American radio talk show host and best selling novelist. I watched the film and I have to say although highly dramatised, with a soundtrack that could rival 'the day after tomorrow', it provides an insight into the possibility of another mass extinction.  The film has caused a media outpour, with the likes of Leonardo DiCaprio tweeting his affection for the film (thats the reason we know it is worth a watch!). 

However, the film has also received criticism for its methane hydrates hypothesis. In the recent IPCC 2013 report, many of the catastrophic changes being forecast were described as likely, unlikely or exceptionally unlikely. The melting of permafrost and the subsequent release of huge reservoirs of methane is deemed exceptionally unlikely, therefore the film has to be taken with a pinch of salt. Why not have a look and make your own judgements. 

Do you think we are in a sixth mass extinction, or are we very close to entering one? 

To end this post here is just a snapshot of some news articles that have documented species extinctions and the catastrophic possibility of another mass extinction.

Ananthaswamy, A (2004) 'Earth faces sixth mass extinction', New Scientist. 

Harvey, F (2013) 'Rate of ocean acidification due to carbon emissions is highest for 300 million years', UK Guardian.

IUNC (2009) 'Wildlife crisis worse than economic crisis', IUNC. 

Mccarthy, M (2011) 'Marine life facing mass extinction within one human generation', Independent. 

Pappas, S (2012) ' Earth's ecosystems nearing catastrophic "tipping point" warn scientists', The  Christian Science Monitor. 

Score board update. 

                                    Anthropocene 1- 0 Biodiversity