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Rising temperatures threaten to drown our forests?

Posted on by Rory Smith
Will rising temperatures create wetter environments? More water means more trees though, right? (Source: YouWall).
Will rising temperatures create wetter environments? More water means more trees though, right? (Source: YouWall)

We all love the view and enchantment of a beautiful forest, at least I know I do. Forests are a place of majesty, exploration and inspiration. They are also arguably the most important vegetation zone on the planet (Myers, 1989).

I have spent the past four months exploring and hiking up as many trails as my legs would allow while staying in a wood cabin in the amazing Colville Forest, Washington. During my stay, I had a lot of time to think to myself and experience nature. I became inspired, inspired to inform others of the dangers that threaten a place I have grown to treasure and so many others hold dear.

Colville National Forest – a splendour of natural beauty (Source: USDA).
Colville National Forest – a splendour of natural beauty (Source: USDA).

Global warming and climate change:

Climate change, is the most pressing environmental concern of our time (Solomon et al., 2009).

Atmospheric carbon dioxide (CO2) levels have been rising since the industrial revolution, and temperatures have been rising ever since (Thuiller, 2007). Temperatures have risen 0.6oC since before the industrial revolution (Lawlor, 2005) but with this rising temperature comes many other changes to global climate (Jump and Penuelas, 2005).

One of the key changes in climate is a different rainfall pattern, regions closer to the equator will receive less rain and regions closer to the poles will receive more (Lawlor, 2005).

Source: Columbia Unviersity
Change in precipitation pattern (Source: Columbia University). 

Of course, a reduction in water for trees at low latitudes will produce negative effects, as trees need water to survive. So, surely an increase in water will be a good thing? Won’t more water result in more trees? It can’t do any harm, can it? Yes, yes it can.

Effects of high rainfall and flooding on trees:

Tree roots absorb oxygen (O2) and minerals from pockets of air in the soil (needed for healthy growth) (Kozlowski, 1986), but after an influx of water these air pockets become saturated and the soil compacted. This rapidly reduces O2 levels in soil and can severely reduce tree growth and even kill trees (Kozlowski, 1984; Kozlowski, 1986). These anaerobic (O2 absent) conditions can also cause the growth of harmful fungi, which can infect the tree roots with a range of diseases, potentially killing the trees (Stolzy and Sojka, 1984).

Why does this matter?

Trees are a vital sink of atmospheric CO2 (Canadell and Raupach, 2008), crucially combatting the effects of climate change by absorbing vast amounts each year. During a process called photosynthesis, plants leaves use light energy to convert CO2 and water into O2 and glucose (food). This is the process crucial to combat the effects on climate change.

Climate change is also altering the distribution of species (Fitzpatrick et al., 2008) and unlike animals, plants cannot migrate fast enough to track the changing climate of the future (Jump and Penuelas, 2005). Therefore, plants must withstand and adapt to future changes.

Not only is Colville National Forest at risk, many more breath-taking forests are at risk of the same effects. So, will forests adapt and continue to play an imperative role in the fight against climate change? Or will they perish?

The future is uncertain and this question remains to be answered.

 

Word Count: 500

References:

Lawlor, D.W., 2005. Plant responses to climate change: impacts and adaptation. In Plant Responses to Air Pollution and Global Change. Springer Japan, pp.81-88.

Solomon, S., Plattner, G.K., Knutti, R. and Friedlingstein, P., 2009. Irreversible climate change due to carbon dioxide emissions. Proceedings of the national academy of sciences, 106(6) pp.1704-1709.

Jump, A.S. and Penuelas, J., 2005. Running to stand still: adaptation and the response of plants to rapid climate change. Ecology Letters, 8(9), pp.1010-1020.

Thuiller, W., 2007. Biodiversity: climate change and the ecologist. Nature, 448(7153), pp.550-552.

Kozlowski, T.T., 1986. Soil aeration and growth of forest trees (review article). Scandinavian Journal of Forest Research, 1(1-4), pp.113-123.

Kozlowski, T.T., 1984. Plant responses to flooding of soil. BioScience, 34(3), pp.162-167.

Canadell, J.G. and Raupach, M.R., 2008. Managing forests for climate change mitigation. science, 320(5882), pp.1456-1457.

Stozly, L.H. and Sojka, R.E., 1984. Effects of Flooding on Plant Disease. In: Kozlowski, T.T. ed. Flooding and Plant Growth. London: Academic Press Inc. Ltd, pp. 221-241.

Fitzpatrick, M.C., Gove, A.D., Sanders, N.J. and Dunn, R.R., 2008. Climate change, plant migration, and range collapse in a global biodiversity hotspot: the Banksia (Proteaceae) of Western Australia. Global Change Biology, 14(6), pp.1337-1352.

Myers, N., 1989. The future of forests. The Fragile Environment: The Darwin College Lectures, pp.22-40.



Is Forest Fragmentation The “New” Deforestation?

Posted on by Ariadne Wilkinson
Global Forest Fragmentation is destroying our most important ecosystems.
Global Forest Fragmentation is destroying our most important ecosystems.

 

It’s a well-known fact that deforestation is happening at extreme rates! Just look at the Amazon rainforest, where 20 football pitches worth of trees are removed every minute (Carrington, 2013). These global environmental changes are associated with our topic for today: fragmentation!

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WHAT IS FRAGMENTATION?

Forest fragmentation occurs when the total cover of a native forest is reduced. It is associated with anthropogenic deforestation, and leads to patchy forests and overall forest loss (Murcia, 1995) (Kupfer et al, 2006).

The isolated patches of forested habitats (remnants) in between the cleared forest cover follow the theory of ‘Island Biogeography’. Principles of Island Biogeography link forest fragmentation with biodiversity loss (Kupfer et al, 2006).

This is a good representation of forest fragmentation by Bacles & Jump (2011). The remnants have a drastically different ecosystem than their surroundings, just like an Island’s ecosystem is isolated from the outside world.
This is a good representation of forest fragmentation by Bacles & Jump (2011). The remnants have a drastically different ecosystem than their surroundings, just like an Island’s ecosystem is isolated from the outside world.

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FRAGMENTATION EFFECTS ON ECOSYSTEMS

 

– Microclimate Change (Saunders et al, 1991)

The microclimate within and surrounding the remnant forest is altered in the following ways:

More solar radiation. This restricts shade-tolerant species and encourages the spread of new species of plants (ex. vines, secondary vegetation) and animals to occupy the forest clearings and edges.

The accompanied temperature rise alters soil moisture and nutrient availability, modifying the local vegetation. It also disturbs species interactions and animal foraging behaviours (ex. Carnaby’s cockatoos).

Image by Georgina Steytler: A Carnaby’s Black-Cockatoo (Calyptorbynchus funereus latirostrus). Higher temperatures in fragmented cockatoo habitats reduced their foraging time available, which led to their local extinction in areas of Western Australia (Saunders et al, 1991)
Image by Georgina Steytler: A Carnaby’s Black-Cockatoo (Calyptorbynchus funereus latirostrus). Higher temperatures in fragmented cockatoo habitats reduced their foraging time available, which led to their local extinction in areas of Western Australia (Saunders et al, 1991).

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Stronger winds. Reducing the denseness of the forest leaves it more exposed to penetrating winds. That, amongst other things, changes vegetation structures and food availability for the forest communities.

Increased water flux. Fragmented forests alter the landscape through heavy water flows that erode the topsoil and transport more particulate matter across the forest cover.

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– Isolation (Saunders et al, 1991)

Remnant forest habitats are usually left crowded, with more species than they can actually support. Therefore, over time species will inevitably be lost due to the lack of resources and space available.

Species survival will generally depend on how well they can adapt to new conditions or migrate to new areas. The most rapid extinctions will occur for species with small populations, or ones that are heavily dependent on native vegetation or large territories.

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– Greenhouse Effect

Tropical rainforests store large amounts of carbon. Destroying them releases this stored carbon into the atmosphere and largely contributes to global warming (Laurance et al, 2002).

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MADAGASCAR

Fragmentation is a serious issue for this biodiversity hotspot, and its all due to human activities.

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Fragmentation is a major concern for Madagascar: The original extent of the eastern rainforest was around 3 times larger than what it currently is!

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Prior to human colonisation the forest on the eastern highland spine of Madagascar was 11.2 million ha, but by 1985 it only covered 3.8 million ha (Green & Sussman, 1990). (These satellite images can be found in Conservation Corridor).

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Its size is diminishing due to fires, illegal logging and agricultural deforestation (Ganzhorn et al, 2001).

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The forest on the Eastern Highland spine of the island is shrinking very fast. Forest can only survive within the gullies, where the fires can’t reach it. Image by: Josia Razafindramanana.
The forest on the Eastern Highland spine of the island is shrinking very fast. Forest can only survive within the gullies, where the fires can’t reach it. Image by: Josia Razafindramanana.

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Many larger species have been lost, and the remainder are unlikely to maintain viable populations beyond 2040. Populations of lemurs with fewer than 40 adults cannot survive. Worryingly, none of the remnant patches on the eastern Madagascar forest are large enough to maintain even such populations (Ganzhorn et al, 2001).

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Lemurs are holding on to the trees for dear life. The high rate of fragmentation is a major concern for these primates, as well as for all of Madagascar’s endemic forest ecosystems. Image by Frank Vassen
Lemurs are holding on to the trees for dear life. The high rate of fragmentation is a major concern for these primates, as well as for all of Madagascar’s endemic forest ecosystems. Image by Frank Vassen.

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THE ONLY SAVING GRACE: CONNECTIVITY

Corridors to connect remnants have proven useful when striving to enhance biodiversity.

They can aid the re-colonisation and immigration of species, provide refuge, and help with further species interactions (Saunders et al, 1991) (Laurance et al, 2002).

The size and shape of the remnants can also affect its vulnerability to external factors:

The best conditions for the conservation management of the ecosystems within remnant patches or forest (here they are termed ‘reserves’ from the “Island-like reserves” biogeography theory) can be seen in this image. The theory of forest connectivity is linked to this.

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Word Count: 499

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FOR MORE INFORMATION ON:

Fragmentation effects on ecosystems you can watch: https://www.youtube.com/watch?v=lzf-uX6kGkk

How Madagascar is managing its lemur populations you can watch: https://www.youtube.com/watch?v=ZhOyD79ymJA

 

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REFERENCES:          

          Carrington, D. (2013). Amazon deforestation increased by one-third in past year. [online] the Guardian. Available at: https://www.theguardian.com/environment/2013/nov/15/amazon-deforestation-increased-one-third [Accessed 18 Mar. 2017].

          Ganzhorn, J., Lowry, P., Schatz, G. and Sommer, S. (2001). The biodiversity of Madagascar: one of the world’s hottest hotspots on its way out. Oryx, 35(04), p.346.

          Green, G. and Sussman, R. (1990). Deforestation History of the Eastern Rain Forests of Madagascar from Satellite Images. Science, 248(4952), pp.212-215.

          Kupfer, J., Malanson, G. and Franklin, S. (2006). Not seeing the ocean for the islands: the mediating influence of matrix-based processes on forest fragmentation effects. Global Ecology and Biogeography, 15(1), pp.8-20.

          Laurance, W., Lovejoy, T., Vasconcelos, H., Bruna, E., Didham, R., Stouffer, P., Gascon, C., Bierregaard, R., Laurance, S. and Sampaio, E. (2002). Ecosystem Decay of Amazonian Forest Fragments: a 22-Year Investigation. Conservation Biology, 16(3), pp.605-618.

          Murcia, C. (1995). Edge effects in fragmented forests: implications for conservation. Trends in Ecology & Evolution, 10(2), pp.58-62.

          SAUNDERS, D., HOBBS, R. and MARGULES, C. (1991). Biological Consequences of Ecosystem Fragmentation: A Review. Conservation Biology, 5(1), pp.18-32.

 

 



Eutrophication: A powerful poison to aquatic life

Posted on by Xi Lan

 

3Such tragic pictures were taken in China telling stories of the low-income people who live on fisheries lost their fishes due to the algae bloom. However, this problem does not only present in China: according to reports, during 1972 to 1999 US commercial fisheries lost over 18 million dollars every year due to the poor water quality (National Science Foundation, 2000).

 

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How is it developed?

Under warm and excessive nutrient conditions (e.g., introduction of nitrogen and phosphorus), algae in the lake starts to grow rapidly. In most healthy lakes, all depths are well oxygenated and the species in lakes are diverse. The excessive nutrient loads leads to the dominance of algae to the lakes, in other word, algae bloom. Massive algae bloom in the surface results in water turbidity increasing therefore the sunlight is blocked from underwater plants. Additionally, algae in the lakes has a short lifespan and depletes the oxygen in water causing a death zone along the water column (hypoxia); some algae can release toxins which are deadly to fish (Hallegraeff, 1993). In this stage the amount of fishes along with aquatic plants decreases rapidly. The healthy, well-oxygenated and clear lake becomes turbid, unsightly with few species alive and a disgusting smell.

 

What happens to ecosystem within the lake?
1The submerged aquatic plants which are adapted themselves to original lake conditions (e.g. high concentration of chlorophyll) are almost wiped out from the lakebed during the algae bloom (Jupp and Spence, 1977). In the case of Taihu lake in China, the area covered by submerged aquatic plants was over 530 km2 which reduced to around 300 km2   in 2009 (Qin et al., 2012).

The decreasing amount aquatic plants would have an impact to the zooplanktons. Less coverage of submerged aquatic plants on lakebed means less refuge capacity provided for zooplanktons (SCHRIVER et al., 1995). Therefore, besides the pressure of hypoxia, zooplanktons are struggling to survive at high predation risk.

One pronounced impact of lake eutrophication is the decreasing trend of overall fish population along with rising algal population as oxygen depleted environment is no longer able to hold big fish population as a healthy lake. Aparting from decreasing quantity of fish community, the fish community quality is also under threat. Generally, highly eutrophic lakes often are dominated by ferocious fish species such as carp (Lee and Jones, 1991). They are more adapted to the poorly oxygenated environment and they are voracious predator of zooplanktons that eat algae, which is an enhancing factor of lake eutrophication (Reinertsen et al., 1990). Decreasing fish community diversity could also happen when low oxygen condition driving deep-water living fish coming to open water under oxygen pressure which result in hybrid with open water fish.

 

Human interference to the ecosystem

Under such environmental pressure, countries like China decides to apply biotic approach to solve the algae bloom causing by eutrophication. Deploying algae-munching fish is well-known as approach to regulate algae population (Andersson et al., 1978). However, massive releasing algae-munching fish would dramatically changing the composition of current aquatic community leading unpredictable problems in future.

 

 

 

References

Andersson, G., Berggren, H., Cronberg, G. and Gelin, C. (1978). Effects of planktivorous and benthivorous fish on organisms and water chemistry in eutrophic lakes. Hydrobiologia, 59(1), pp.9-15.

Hallegraeff, G. (1993). A review of harmful algal blooms and their apparent global increase*. Phycologia, 32(2), pp.79-99.

Jupp, B. and Spence, D. (1977). Limitations on Macrophytes in a Eutrophic Lake, Loch Leven: I. Effects of Phytoplankton. The Journal of Ecology, 65(1), p.175.

Lee, G. and Jones, A. (1991). Effects of Eutrophication on Fisheries. Reviews in Aquatic Science, [online] 5(3). Available at: http://www.gfredlee.com/Nutrients/Effects_Eutroph_Fisheries.pdf             [Accessed 22 Mar. 2017].

McKinnon, J. and Taylor, E. (2012). Biodiversity: Species choked and blended. Nature, 482(7385), pp.313-314.

National Science Foundation, (2000). Estimated Annual Economic Impacts from Harmful Algal Blooms (HABs) in the United States. [online] National Science Foundation. Available at:                       http://www.whoi.edu/cms/files/Economics_report_18564_23050.pdf [Accessed 22 Mar. 2017].

Qin, B., Gao, G., Zhu, G., Zhang, Y., Song, Y., Tang, X., Xu, H. and Deng, J. (2012). Lake eutrophication and its ecosystem response. Chinese Science Bulletin, 58(9), pp.961-970.

Reinertsen, H., Jensen, A., Koksvik, J., Langeland, A. and Olsen, Y. (1990). Effects of Fish Removal on the Limnetic Ecosystem of a Eutrophic Lake. Canadian Journal of Fisheries and Aquatic             Sciences, 47(1), pp.166-173.

SCHRIVER, P., BOGESTRAND, J., JEPPESEN, E. and SoNDERGAARD, M. (1995). Impact of submerged macrophytes on fish-zooplanl phytoplankton interactions: large-scale enclosure                         experiments in a shallow eutrophic lake. Freshwater Biology, 33(2), pp.255-270.

 

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From global warming to global mourning: the effects of climate change on plants

Posted on by Anonymous

Ignore Trump, global warming is real. Climate change can be traced back to as early as 1896, where the Swedish chemist Svante Arrhenius first predicted human activities to affect atmospheric carbon dioxide (CO2) levels (NASA, 1998).

More than one hundred years on, Arrhenius is yet to be proved wrong.

Today, human-induced global change is taking many forms. From increased greenhouse gases to changes in global surface temperature, all species are under threat. The effects on plant functions are particularly important. After all, we need plants for our basic survival – try breathing or eating without them!

Greenhouse gases

Consistent with Arrhenius’ ideas, CO2 levels have increased drastically over the last 250 years (Ainsworth et al., 2008). Plants are dependent on CO2 for photosynthesis, where sunlight converts absorbed CO2 into sugar and oxygen. As carbon is extremely important in plants, forming 45% of their dry mass (Fangmeier et al., 2002), it can only be predicated that this increase will be beneficial to them, right?

An experiment looking at the responses of soybean to elevated CO2 concentrations shines a light on this idea. Results showed that plants were generally positively affected by elevated levels of CO2, shown by an increase in photosynthesis, water-use efficiency and biomass (Ainsworth et al., 2006).

So, what’s the problem with increased CO2? Fundamentally, elevated CO2 reduces the stomatal conductance in plants (the amount of CO2 entering the pore-like components of leaves) (Ainsworth et al., 2006). You may not believe it, but plants are cleverer than you think! A reduction in stomatal pores for gas exchange actually shows that plants are adapting to modern-day conditions by reducing their water loss and enhancing their survival (Beerling & Chaloner, 1993b).

17165920835_de7cf710ef_o-1
Figure 1. Stomata shown on the underside of a leaf.

Other than CO2, increased ozone (O3) also affects plant function. It ages them (a process called senescence, quite different from the old wrinkly plants your imagining), reduces their growth and yield (Fangmeier et al., 2002), and disturbs nutrient levels, shown in snapbeans (Tingey et al., 1986) for example.

Temperature

Oh, and there’s more: rising CO2 has led to a 0.76°C increase in global surface temperature since the 1800s (Ainsworth et al., 2008). With this comes disturbances in pollination timing, alongside increased drought disrupting conditions for efficient plant growth. This has been shown in Australia, where extreme temperature, drought and lowered sea levels resulted in severe mangrove “dieback” (The Guardian, 2017) (see full article here: https://www.theguardian.com/commentisfree/2017/mar/14/gulf-of-carpentarias-record-mangrove-dieback-is-a-case-study-of-extremes).

mangrove-image
Figure 2. The effect of global environment change on mangroves in Australia’s Gulf of Carpentaria.

What about in the long-term?

For plants: Despite the adaption of plants in the short-term, it is unknown how global change will affect them in the long run. However, a photosynthetic acclimation is expected, accompanied by higher carbohydrate concentrations, lower soluble proteins and inhibition of photosynthetic capacity (Drake et al., 1997).

For humans: Plant function and agricultural systems are tightly interlinked, therefore the negative effects of global change could potentially lead to food insecurity. With an estimated 60% increase in global cereal demand by 2050 (Rosegrant and Cline, 2003), the understanding of future plant responses could shape the fate of humanity!

Word count: 490 words

References:

Ainsworth, E.A., Rogers, A. and Leakey, A.D., 2008. Targets for crop biotechnology in a future high-CO2 and high-O3 world. Plant physiology, 147(1), pp.13-19.

Ainsworth, E.A., Rogers, A., Vodkin, L.O., Walter, A. and Schurr, U., 2006. The effects of elevated CO2 concentration on soybean gene expression. An analysis of growing and mature leaves. Plant Physiology, 142(1), pp.135-147.

Beerling, D.J. and Chaloner, W.G., 1993. The impact of atmospheric CO2 and temperature changes on stomatal density: observation from Quercus robur lammas leaves. Annals of Botany, 71(3), pp.231-235.

Drake, B.G., Gonzàlez-Meler, M.A. and Long, S.P., 1997. More efficient plants: a consequence of rising atmospheric CO2?. Annual review of plant biology, 48(1), pp.609-639.

Fangmeier, A., De Temmerman, L., Black, C., Persson, K. and Vorne, V., 2002. Effects of elevated CO 2 and/or ozone on nutrient concentrations and nutrient uptake of potatoes. European Journal of Agronomy, 17(4), pp.353-368.

NASA., 1998. Global Warming. TAPPI JOURNAL.

Rosegrant, M.W. and Cline, S.A., 2003. Global food security: challenges and policies. Science, 302(5652), pp.1917-1919.

The Guardian. (2017). Gulf of Carpentaria’s record mangrove dieback is a case study of extremes. [online] Available at: https://www.theguardian.com/commentisfree/2017/mar/14/gulf-of-carpentarias-record-mangrove-dieback-is-a-case-study-of-extremes [Accessed 19 Mar. 2017].

Tingey, D.T., Rodecap, K.D., Lee, E.H., Moser, T.J. and Hogsett, W.E., 1986. Ozone alters the concentrations of nutrients in bean tissue (No. PB-88-149133/XAB; EPA-600/J-86/431). Environmental Protection Agency, Corvallis, OR (USA). Environmental Research Lab..



Bloom and Bust

Posted on by Lauren Furmidge
‘Blue Marble’ –Earth as seen by Apollo 17 (NASA/ Apollo 17 Crew, 1972)

 

In 1972, one of the most iconic photographs of the Earth was taken from space.  The ‘Blue Marble’ snapped by the astronauts aboard Apollo 17 shows an Earth with deep blue oceans but very little greenery on the land. Now photographs of the Earth from space look very different, with luscious green patches where there was once dull brown.  The spreading and growing of green vegetation is a result of rising CO2 levels in the Earth’s atmosphere.  The Earth has undergone an increase of 18 square kilometres of new vegetation between 1982 and 2009 (Keenan et al., 2016).

 

Since the Industrial Revolution, the burning of fossil fuels such as coal and oil by humans has caused an enormous rise in atmospheric CO2 from 280ppm to over 400ppm today, inducing disastrous effects on the environment such as climate change (Khatiwala et al., 2009).

So if increases in CO2 are so bad, why is a boom in plant growth occurring?

 

Plants use CO2 in photosynthesis; a process in which plants use CO2, water and light from the sun to produce sugars for growth and oxygen which they give off.  The increased rates of photosynthesis are down to a chemical called Rubisco, which helps incorporate CO2 into the photosynthesis process.  Rubisco first evolved long, long ago- far before humans began affecting the world.  At this point in history CO2 levels were much greater than during recent times.  This means that Rubisco is less efficient at lower CO2 levels.  As humans have begun to disturb these lower CO2 concentrations and caused them to rise, Rubisco works better meaning plants are able to photosynthesise at a greater rate, which increases their growth (Taylor et al., 1994).

 

Sun through leaves (Shuttershock, 2013)
Sun through leaves (Shuttershock, 2013)

 

Although this appears to be all good news for the plants, rising atmospheric CO2 levels also bring negative effects, one of them being climate change.  With increasing CO2 comes increases in temperature which can negatively impact plants.  Plants require an optimum temperature in order to survive well and if they are not able to shift their ranges, they will suffer the effects of warmer, dryer environments which are ultimately inhospitable (Hatfield and Prueger, 2015).  So whilst plants prosper in the short term, when temperatures get too high they languish.

Also, there is evidence that rising CO2 reduces the ability of stomata- small pores on plants- to conduct CO2 and perform transpiration- the removal of water-, ultimately leading to reduced photosynthesis (Drake et al., 1997).

 

Although rising CO2 has turned the brown swathes of Earth captured in the ‘Blue Marble’ into luscious green, behind this initial bloom lurks an ominous truth. If humans continue to fuel rising CO2 levels, plants will suffer and food crops will fail. Global temperature increases, rainfall changes and extreme weather events- droughts and floods- jeopardise the functions of plants, ultimately devastating them.

 

Word Count: 468

 

 

References

Drake, B.G., Gonzalez-Meler, M.A., Long, S.P.,1997. More efficient plants: a consequence of rising atmospheric CO? Annu. Rev. Plant Physiol. Plant Mol. Biol. 48, 609 – 639.

Hatfield, J.L. and Prueger, J.H., 2015. Temperature extremes: effect on plant growth and development. Weather and Climate Extremes, 10, pp.4-10.

Keenan, T.F., Prentice, I.C., Canadell, J.G., Williams, C.A., Wang, H., Raupach, M. and Collatz, G.J., 2016. Recent pause in the growth rate of atmospheric CO2 due to enhanced terrestrial carbon uptake. Nature communications, 7.

Khatiwala, S., Primeau, F. and Hall, T., 2009. Reconstruction of the history of anthropogenic CO2 concentrations in the ocean. Nature, 462(7271), pp.346-349.

NASA/ Apollo 17 Crew., 1972., ‘Blue Marble’ –Earth as seen by Apollo 17. [Photograph]

Shuttershock., 2013., Sun through leaves. [Photograph]

Taylor, G., Ranasinghe, S., Bosac, C., Gardner, S.D.L. and Ferris, R., 1994. Elevated CO2 and plant growth: cellular mechanisms and responses of whole plants. Journal of Experimental Botany, 45(Special Issue), pp.1761-1774.

 

 



Fragmentation devastation: Why terrestrial habitats around the globe are being pushed over the edge.

Posted on by Dmitri Dharmasena

Habitat fragmentation is a term describing the process by which a large  habitat is broken up into numerous smaller habitats of decreased area and size, separated by a matrix of new unfamiliar habitat types – driven by the action of habitat loss (Didham, R.K., 2010). The loss of habitat through fragmentation is thought to be one of the main drivers of global biodiversity loss and can be either naturally occurring (climate change, volcanism, fires etc.) or human induced.

 

“70% of remaining forest is within 1km of the forest edge..” (Haddad et al, 2015)

 

Figure 1: The process of habitat fragmentation shown over time. Black regions represent areas of habitat and white regions represent newly formed matrix habitats. (Source: Fahrig, 2003).
Figure 1: The process of habitat fragmentation shown over time. Black regions represent areas of habitat and white regions represent newly formed matrix habitats. (Source: Fahrig, 2003).

 

What are the major effects of habitat fragmentation?

A long term global forest fragmentation study revealed that decreases in fragment area and an increase in fragment isolation, generally causes a drop in the abundance of:

  • Mammals
  • Birds
  • Insects
  • Plants

In tropical forests, reduced fragment sizes led to an increase in the portion of edge habitat exposed to unfamiliar surroundings. Following the increase in edge habitat, a shift in the physical environment was observed which caused a subsequent loss in the oldest and largest trees from these fragments, which had knock-on impacts on the wider community and specifically insect community compositions (Haddad et al, 2015).

Figure 2: Fragmented forests in the tropics.
Figure 2: Forest fragmentation in the tropics (Source: ALERT, 2015).

Fragmentation also effects communities through alterations of predator-prey interactions. It has been theorised that specialist predators are affected more severely by the fragmentation than their prey leading to a lower specialist predator abundance (Ryall & Fahrig, 2006). Generalist predators whom live predominantly within the matrix are thought to be benefited by increased fragmentation, so long as the new matrix is able to provide the generalist predator with alternative resources (Ryall & Fahrig, 2006). These adjustments will have cascading effects down through communities due to a rise or fall in the populations of top predators and their prey.

 

What is being done to help?

Case study: The Bhutanese Tiger corridor

One mechanism that has been implemented around the world is the use of ‘wildlife corridors’ (Silveira et al, 2015), which serve to reconnect fragmented patches of habitat. The Bhutanese Tiger corridor, from Northern India into Bhutan (see figure 2) has proven that this method does work. The corridor connects isolated Tiger habitats that now allow free passage for Tigers and other community species across a far greater space of land. Since its introduction the Bhutanese Tiger population has risen by more than a third of its previous population estimate.

Figure 2: A map visualising the Tiger corridor implemented between North Eastern India and Bhutan.
Figure 3: A map visualising the Tiger corridor implemented between North Eastern India and Bhutan (Source: Broad, 2012).

 

Fragmentation induces diverse changes that progressively filter through ecosystems. It  considerably lowers species richness of both plants and animals and in many cases it has impacted the structure and make up of entire animal communities. Habitat fragmentation is therefore an extreme threat to virtually all terrestrial biodiversity. Consequently, conservation efforts and habitat restoration projects must being immediately in order to prevent catastrophic losses and extinctions of some of the most iconic species on earth.

 

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References

  • ALERT, (2017). Forest fragmentation in the tropics.. [image] Available at: http://alert-conservation.org [Accessed 21 Mar. 2017].
  • Broad, M. (2012). NE Indian Tiger corridor. [image] Available at: http://pictures-of-cats.org/the-tigers-of-bhutan.html [Accessed 20 Mar. 2017].
  • Didham, R.K., 2010. Ecological consequences of habitat fragmentation. eLS.
  • Fahrig, L., 2003. Effects of habitat fragmentation on biodiversity. Annual review of ecology, evolution, and systematics, 34(1), pp.487-515.
  • Haddad, N.M., Brudvig, L.A., Clobert, J., Davies, K.F., Gonzalez, A., Holt, R.D., Lovejoy, T.E., Sexton, J.O., Austin, M.P., Collins, C.D. and Cook, W.M., 2015. Habitat fragmentation and its lasting impact on Earth’s ecosystems. Science Advances, 1(2).
  • Ryall, K.L. and Fahrig, L., 2006. Response of predators to loss and fragmentation of prey habitat: a review of theory. Ecology, 87(5), pp.1086-1093.
  • Silveira, L., Sollmann, R., Jácomo, A.T., Diniz Filho, J.A. and Tôrres, N.M., 2014. The potential for large-scale wildlife corridors between protected areas in Brazil using the jaguar as a model species. Landscape ecology, 29(7), pp.1213-1223.

 



Combatting the change: we must not forget the global change indicators under our feet and above our heads

Posted on by Ellen Williams

The world as we know it, and the species within it, are experiencing rapid changes (MEA, 2005). Us humans are the monsters, with our activity having a huge global impact. This human-induced activity can take many forms, including land-use change, increased CO2 and nitrogen concentration. Many complex interactions exist in the natural world, involving predation and competition, but recent human-induced changes have added great pressure, termed global change (Vitousek, 1994), to these intermingled global connections:

“It would not be surprising to see entire patterns of community organisation jumbled as a result of global change.” (Kareiva et al. 1993).

How can this happen?

Synthetic fertiliser production and industrial processes using fossil fuels over the past 50 years have led to an increase in nitrogen deposition (Suddick et al. 2013). This can consequently result in eutrophication: a literal example of ‘too much of a good thing’, which is explained here:

Nitrogen eutrophication can lead to a great decline in species richness (Börgstrom et al., 2017) but it affects interactions between these species, some which we can and some which we cannot see: An individual species is always part of a bigger story, with the effects of nitrogen eutrophication cascading through many chapters. It is hard to study these hidden interactions, for obvious reasons! But it provides a complete view of what is going on in an ecosystem. It is important to note that drivers of global change do not work in isolation: for example, increasing temperatures only aggravate the effects of nitrogen deposition.

But, how does this work?

For example, insect herbivores above- and below-ground will interact differently in response to nitrogen eutrophication. This has a knock-on effect on the composition of the plant community; affecting worms in the soil, and land mammals which graze on the plants (Börgstrom et al., 2017). Plants gain positively from nitrogen deposition by improved nectar quality and abundance of flowers, yet the negative effects of increased competition outweigh these positives, resulting in a net reduction in pollination. Which again, may have a knock-on effect on seed dispersal by a fruit-eating animal, for example. It can also result in increased plant fungal diseases! (Parmesan, 2006)

Nitrogen deposition favours those plant species which are better adapted to a higher nitrogen concentration, which increases competition between species.

What about on a larger scale?

Migratory birds could potentially connect different ecosystems (Hessen et al. 2017). Eutrophication strongly impacts Arctic freshwater ecosystems, due to increasing geese populations in temperate regions, and improved breeding success in the Arctic. The faeces from the geese provide the environment with increased nutrients (who knew this could be beneficial?!), which can affect the composition of the plant community.

Migrating geese. From: www.planet-science.com.

But, how does this affect us?

Understanding how communities and entire ecosystems respond to nitrogen deposition is important, as our well-being depends on the services they provide, such as wood production and food. Given that effects of global change are widespread (thanks, geese!), an international management of ecosystems will prove useful in the future.

References

Börgstrom, P et al. (2017). Above- and belowground insect herbivory modifies the response of a grassland plant community to nitrogen eutrophication. Ecology. 98:545- 554.

Hessen DO et al. (2017) Global change and ecosystem connectivity: How geese link fields of central Europe to eutrophication of Arctic freshwaters. Ambio. 46:40-47.

Kareiva, PM et al. (1993). Introduction. In: Biotic Interactions and Global Change (eds Kareiva, P.M., King- solver, J.G. & Huey, R.B.). Sinauer Associates Inc., Sunderland, MA, pp. 1–6.

Millennium Ecosystem Assessment (MEA) (2005). Ecosystems and Human Well-Being: Scenarios. Island Press, Washington, DC.

Parmesan, C. (2006). Ecological and evolutionary responses to recent climate change. Annu. Rev. Ecol. Evol. Syst., 37, 637–669.

Suddick EC et al. (2013) The role of nitrogen in climate change and the impacts of nitrogen-climate interactions in the United States: foreword to thematic issue. Biogeochemistry. 114(1):1-10.

Vitousek PM (1994) BEYOND GLOBAL WARMING: ECOLOGY AND GLOBAL CHANGE. Ecology. 75(7):1861-1876.

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The tide is high but I’m holding on: The effect of rising sea level on wetlands

Posted on by Sophie Gibson

Sea levels have been rising over the years due to water expansion and glaciers melting (Jacob et al, 2012). Unfortunately unlike Blondie not all of our coastal systems can ‘hold on’ and survive this. There have been effects on wetlands (Scavia, 2002) such as marshes and mangroves by:

  • Inundation (flooding)
  • Salt water intrusion
  • Erosion

 

Marshes 

A flooded marsh being broken up due to flooding. Image from: http://www.learnnc.org/lp/editions/cede_sealevel/373
A salt marsh being broken up due to flooding. Image from: www.learnnc.org

Rising sea levels increase the frequency and duration of tidal flooding in marshes (Titus, 1988). If these marshes are supplied with additional sediment then they can retreat landwards and keep up with sea level rise.  However if they aren’t Usain Bolt enough to outrun sea level, the marsh grass drowns, soil erodes and the system is lost and often becomes open water. This usually occurs in salt water coastal marshes (Scavia et al, 2002).                                                                                  

Another effect of rising sea level allows salt water to move upstream and inland to the freshwater marshes, causing them to transition into a brackish (slightly salty) marsh. Often, a response is to replace freshwater species with more salt tolerant species, therefore changing the biodiversity and functioning of the system.

Marshes are very important as nursery grounds, giving protection to marine invertebrates and fish larvae and are also an important food source for aquatic birds such as sandpipers as well as other large animals (Titus, 1988). They are also vastly important for humans as they provide services associated with waste treatment and productivity. These processes will likely be affected with the reduction of salt marshes and the transition of fresh water marshes to brackish (Craft et al, 2009).

 

Video summarising the effects of sea level rise on marshes. 

Mangroves 

Mangrove roots supporting biodiversity. Image from: http://www.bbc.co.uk/nature/habitats/Mangrove
Mangrove roots supporting biodiversity.                 Image from: www.bbc.co.uk

Mangroves adjust to a rising sea level by moving into areas of higher elevation. This movement however can be limited by obstacles, steep gradients and the amount of sediment accumulation (Gilman et al, 2008). Different species have different colonisation speeds, leading to competition between species. This can cause some to become more dominant than others, affecting biodiversity. (Di Nitto et al, 2014). 

Mangroves can’t always move faster than sea level rise and the increased flooding can cause roots to weaken, trees to die and the system to become open water. Even when they are able to move, many mangroves are losing elevation relative to sea level (Gilman et al, 2008) (Lovelock et al, 2015).

 Mangroves are important:

  • For supporting biodiversity
  • As fishery nursery habitats
  • For coastal protection 
  • For carbon uptake

 

and are therefore relied on by many human communities (Di Nitto et al, 2014). These effects are likely to get worse in the coming years and therefore more research should be carried out and protection plans put in place. 

Scale model showing how mangrove forests protect the coast from wave erosion.

Overall wetlands are thought to be most affected on the Atlantic Coast of Central and North America, Caribbean islands, the Mediterranean and Baltic (Nicholls, Hoozemans And Marchand, 1999). So remember, wetlands aren’t just some soggy plants! They are vital ecosystems that have important functions and their loss could cause many issues especially in the coming years as sea level continues to rise. 

References 

Craft, C., Clough, J., Ehman, J., Joye, S., Park, R., Pennings, S., Guo, H. and Machmuller, M. (2009). Forecasting the effects of accelerated sea-level rise on tidal marsh ecosystem services. Frontiers in Ecology and the Environment, 7(2), pp.73-78.

Di Nitto, D., Neukermans, G., Koedam, N., Defever, H., Pattyn, F., Kairo, J. and Dahdouh-Guebas, F. (2014). Mangroves facing climate change: landward migration potential in response to projected scenarios of sea level rise. Biogeosciences, 11(3), pp.857-871.

Gilman, E., Ellison, J., Duke, N. and Field, C. (2008). Threats to mangroves from climate change and adaptation options: A review. Aquatic Botany, 89(2), pp.237-250.

Jacob, T., Wahr, J., Pfeffer, W. and Swenson, S. (2012). Recent contributions of glaciers and ice caps to sea level rise. Nature, 482(7386), pp.514-518.

Lovelock, C., Cahoon, D., Friess, D., Guntenspergen, G., Krauss, K., Reef, R., Rogers, K., Saunders, M., Sidik, F., Swales, A., Saintilan, N., Thuyen, L. and Triet, T. (2015). The vulnerability of Indo-Pacific mangrove forests to sea-level rise. Nature, 526(7574), pp.559-563.

Nicholls, R., Hoozemans, F. and Marchand, M. (1999). Increasing flood risk and wetland losses due to global sea-level rise: regional and global analyses. Global Environmental Change, 9, pp.S69-S87.

Scavia, D., Field, J., Boesch, D., Buddemeier, R., Burkett, V., Cayan, D., Fogarty, M., Harwell, M., Howarth, R., Mason, C., Reed, D., Royer, T., Sallenger, A. and Titus, J. (2002). Climate change impacts on U.S. Coastal and Marine Ecosystems. Estuaries, 25(2), pp.149-164.

Titus, J. (1988) Sea Level Rise and Wetland Loss: An Overview U.S Environmental Protection Agency.

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We need to change today, not the day after tomorrow…

Posted on by Alexandra Loveridge

The evidence for global environmental change is overwhelming. Increased levels of CO2 and other pollutants in the atmosphere cause constant and gradual increases in the average global temperature.  This is largely the fault of human activity through the burning of fossil fuels and the release of greenhouse gases. Carbon dioxide is long lived in our atmosphere and so these changes will continue happening for a long time even if we stop producing greenhouse gases.

img_0421
A tree line so straight it could have been drawn on with a ruler.

 

Have you ever gone to the mountains and wondered why there is a distinct sequence in the types of trees you see: deciduous, evergreen, then a well defined tree line above which there are rarely any trees?

This is because most plants can only live in very specific conditions. But global change will increase the amount of CO2 in the atmosphere, which warms the environment…

 

 

What does global environmental change mean for plants in the future?

 

 

 

Firstly, there will be a higher rate of photosynthesis under increased CO2. Rubisco, a key part of the photosynthetic process that fixes CO2, evolved at a time when there was a higher proportion of CO2 in the atmosphere. Under today’s much lower CO2 levels, this enzyme is far less efficient because Rubisco also fixes oxygen, wasting energy. So for plants, more CO2 in the environment means more photosynthesis, right?

Not necessarily true! Bowes (1993) suggested that at high levels of CO2 for a long time some plants may decrease the number of pores (stomata) that absorb CO2 on their leaves and the rate of photosynthesis may actually decrease. As well as this, changes to precipitation and nutrient supply may stop plants from reaching their full photosynthetic potential.

Secondly, rates of growth increase when plants are subjected to higher levels of CO2. Taylor et al. (1994) found that leaves and roots were bigger under higher levels of CO2 and also found that individual cells in the roots got larger too. However, some plants are already living on the edge of their physiological limits and cannot adapt. This may lead to some species dying out if they cannot adapt to the conditions quickly enough.

The UK: a future tropical paradise? Quite unlikely…

Finally plants will need to be hardier to withstand increased temperatures and occurrences of extreme weather events… Some plants have found a clever way to get around the warming problem. In the mountains, trees have gradually been moving higher up to avoid the warmer temperatures (Thuiller et al., 2005). As well as this, species such as mangroves are also shifting north (Field, 1995). This change in latitude is called a range shift. This doesn’t, however, mean that the future beaches around Britain will be warm and sunny and covered in palm trees unfortunately…

 

These changes will have a huge impact on society through reduced food security, changes to our water and power supplies, and may even impact on our health.

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Its not the end of the world quite yet!

How do you think we can reduce these risks? What can people do to reduce their impact on the planet? Leave your thoughts and comments below!

Word Count: 499

All photographs taken by Sophie Loveridge.

 

References

  • Monleon, V. and Lintz, H. (2015). Evidence of Tree Species’ Range Shifts in a Complex Landscape. PLOS ONE, 10(1), p.e0118069.
  • Field, C. (1995). Impact of expected climate change on mangroves. Hydrobiologia, 295(1-3), pp.75-81.
  • Bowes, G. (1993). Facing the Inevitable: Plants and Increasing Atmospheric CO2. Annual Review of Plant Physiology and Plant Molecular Biology, 44(1), pp.309-332.
  • Thuiller, W., Lavorel, S., Araujo, M., Sykes, M. and Prentice, I. (2005). Climate change threats to plant diversity in Europe. Proceedings of the National Academy of Sciences, 102(23), pp.8245-8250.
  • Taylor, G., Ranasinghe, S., Bosac, C., Gardner, S. and Ferris, R. (1994). Elevated CO2 and plant growth: cellular mechanisms and responses of whole plants. Journal of Experimental Botany, 45(Special_Issue), pp.1761-1774.


Believe it or not… CLIMATE CHANGE WILL TRUMP U.S.!

Posted on by Hannah Lesbirel

By Hannah Lesbirel student at University of Southampton

You’ve all seen images of famine and the effect of crop failure on families across the globe. Have you ever pictured that being you? No, me neither.

Surely that can’t happen in the USA- “The greatest country in the World”- people say?

Queues for food rations. This is happening somewhere in the world right now! Imagine, this could be you if nothing is done to reduce the impacts of climate change. Source: http://answersafrica.com/starvation-and-famine-in-africa.htm
Queues for food rations. This is happening somewhere in the world right now! Imagine, this could be you if nothing is done to reduce the impacts of climate change. Source: AnswerAfrica

Some experts argue the increase in CO2 levels, associated with climate change, may in fact contribute to gains in some crops, in some regions of the world. Surely more CO2 means more photosynthesis, right?

However, the negative impacts associated with climate change are expected to reverse the potential benefits (Nelson et al., 2009). Climate change indisputably impacts: global temperatures, frequency and intensity of extreme weather events, CO2 levels and water availability, and without availability of sufficient water and nutrients photosynthesis can’t thrive (Nelson et al., 2009; Hatfield et al., 2011).

The video below summarises the limiting factors of photosynthesis and how they could be influenced by the changing environment.

Temperature Variability

The rate of plant development is primarily influenced by temperature, impacting (Hatfield and Prueger, 2015);

  • Pollen viability
  • Fertilisation
  • Water requirements
  • Grain and fruit formation
  • Length of life cycle

All plants have an optimum temperature in which photosynthesis takes place, too high and enzymes are denatured and too low the catalytic efficiency of these enzymes are reduced. Additionally, higher temperatures are known to encourage weeds, pests and disease.  The figure below shows the predicted temperature due to climate change globally by 2050 (Nelson et al., 2009). If this rise in temperature is to continue, this will reduce crop yields across the globe.

Source: Nelson et al., 2009
Predicted increase in global temperatures by 2050. Source: Nelson et al., 2009
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Once luscious fields becoming barren due to decreased yields as a results of climate change. Source: Crated and Nature 

With warmer temperatures predicted along with the increased probability of extreme temperature events, plant productivity is at serious RISK! Estimations show a significant decline in yields, of between 80-90%, compared to ‘normal’ conditions (Hatfield and Prueger, 2015).

Changes in Precipitation

The concern of rising global temperatures, will be proliferated by changes in precipitation. Increasing the likelihood of crop failure and long term production decline (Nelson et al., 2009).

Despite uncertainty in precipitation change, under future climate change scenarios, the impact of excess and deficit amounts of soil water will be negative for crop production, either drowning or starving the crops of water (Hatfield et al., 2011).

It’s been said that “stronger interannual variability with more extreme year-to-year climate variations…[means] farmers are unable to tune their cropping systems to optimize resources (Bannayan et al., 2010).”

Not only will this have a major impact on human health and well-being. Agriculture contributes over $300 billion to the U.S. economy each year; think of the impact this may have on your health and livelihood.

Decline of Global Markets

On a more global scale, the potential decline in production will reach international levels, as U.S. farms supply 25% of all grain (soybean, wheat and maize) on the global markets (Nelson et al., 2009; USEPA, 2016).

screen-shot-2017-03-06-at-13-24-35
The cycle that could follow the decline in grain production (Nelson et al., 2009).

The ‘domino’ effect of a decline in grain productivity is incomprehensible. The cycle that could follow is shows to the right.

Could we be building a wall between us and future generations? Progress is needed to prevent this shocking reality.

Read more information about the impact of Climate Change on global agriculture from the FAO report on Climate change: Impact on Agriculture and Costs of Adaptation.

 

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Read More:

http://ecoethics.net/cyprus-institute.us/PDF/Rosensweig-Food-Supply.pdf

http://bioenv.gu.se/digitalAssets/1432/1432197_fantahun.pdf

http://www.pnas.org/content/106/37/15594.full