Global Change Ecology (BIO347)

Population control

Most of the environmental problems nowadays like climate change and biodiversity loss, have one thing in common, human overpopulation. According to United Nations the world populations will reach around 9 billion people in 2050 with their ever demanding need for food and fresh water [1], prospects are not looking good. Drastic measures need to take place and in the world we live in nowadays it looks like that is not going to happen. On the climate convention in 2009 in Copenhagen it was decided that temperatures should not raise any more than 2 degrees Celsius without any nations that really wanted to give in [1]. Instead of countries trying to bring down their CO2 emissions they’ve resulted in a global trade of ‘fresh air’ . Belgium for example has spent around 194 million euros on fresh air in order to meet the Kyoto norms [2]. Public awareness is simply too low for governments to take any drastic measures, in the Netherlands for example the green minded party GroenLinks, has since foundation in 1990 never been part of the government and at the last elections they only received 2.3 percent of the overall votes [3].
Democracy seems a great way to govern a country where everybody has an equal vote, but when it comes to affairs that are greater than the wellbeing of a nations inhabitants it seems like it doesn’t work. Every party that has some drastic ideas concerning the environmental preservation, doesn’t get a place in the government because people mostly don’t care, vote in regard to their own wellbeing and they cannot directly perceive the measures a party takes because it takes a long time to notice any environmental change, let alone some ideas about population control which has been established in China a communistic country [4].
Because let’s face it the best way to preserve our environment and wildlife is not by trying to lower our ecological footprint but to control human population growth and preferably make it decline but since that is not a priority in most western countries further boundaries need to be established.

References
1. www.un.org
2. http://www.hln.be België koopt «schone lucht» vooral in het buitenland. 20/11/2013
3. www.parlement.com GroenLinks
4. http://www.telegraph.co.uk/ What is China’s one-child policy? 30/9/2014

Alien species dilemma

Non-native species that have been introduced by humans over the past decades have been known to cause a lot of trouble. For example the introduction of rabbits in Australia who were introduced for the hunting sport but quickly caused the most rapid invasion of animals ever recorded(Animal Control Technologies Australia), or the Nile perch that was introduced in lake Victoria and completely disrupted the lakes ecosystem (Ogutu-ohwayo 1990). All for various reasons, whether it is for the hunting or fishing sport, as with the rabbits and some fish species, or to kill a plague in an area, after which the introduced species handled themselves better than expected (Philips & Shine 2006). Internationalisation doesn’t help much either. Almost every kind of species which is farmed or bred can be spread almost all around the world and are being introduced into an area in which it is not native, where escapees or pollen can cause a lot of trouble on both economical and environmental scales. Transport these enables humans to travel to the other side of world while we unknowingly spread all kinds of plant seeds, spores or even eggs from insects for example (Mack & Lonsdale 2001, Keth 1999). All in all humans have become a greater form of global dispersal rather than mother nature itself we have given the non-native or alien species a very bad reputation.
But we should also consider this, it is by all means clear that humans have had a bigger impact on the global ecosystem than all directly or indirectly introduced species combined, mainly by changing the native species’ original habitat in all kinds of ways (Davis 2011). It is therefore not remarkable that non-native species do so well since the original habitat has shifted to a state not suitable anymore for some native species, and because a lot of non-native species are either intentionally or unintentionally introduced, there is bound to be one or more species among them that are able to adapt to the new environment (Davis 2011). Since we might be too late to restore habitats in their original state (and yet we still try to), an article by Mark Davis argues that rather than trying to get rid of non-native species we should embrace them and maybe use them to our benefits. The article mentions for example that tamarisks, which have been introduced from Europe and Asia to America, fulfil in the habitat the same role as the species it outcompeted in the first place.
Non-native species will be introduced everywhere around the world whether we want it or not. Instead of preventing introductions we should maybe do more research in using alien species to our advantage. We changed to world in major way ourselves, so we should just deal with the consequences.

References

Davis, M. A., Chew, M. K., Hobbs, R. J., Lugo, A. E., Ewel, J. J., Vermeij, G. J., Brwon, J. H., Rosenzweig, M. L., Gardener, M. R., Carroll, S. P., Thompson, K., Pickett, S. T. A., Stromberg, J. C., Del Tredici, P., Suding, K. N., Ehrenfeld, J. G., Grime, J. P., Mascaro, J., Briggs J. C. 2011. Don’t judge species on their origins. Nature 474, 153-154, 09 June 2011.

Keth, A.C. 1999. Three Incidents of Human Myiasis by Rodent Cuterebra (Diptera: Cuterebridae) Larvae in a Localized Region of Western Pennsylvania. Journal of Medical Entomology, Volume 36, Issue 6, 1 November 1999.

Mack, R. N., Lonasdale, W. M. 2001. Humans as Global Plant Dispersers: Getting More Than We Bargained For. Bioscience 51 (2): 95-102, 2001)

Ogutu-Ohwayo, R. 1990. The decline of the native fishes of lakes Victoria and Kyoga (East Africa) and the impact of the introduced species, especially the Nile perch, Lates niloticus, and the Nile tilapia, Oreochromis niloticus*. Evironmental Biology of Fishes 27: 81-96, 1990.

Philips, B. L., Shine, R. 2006. An invasive species induces rapid adaptive change in a native predator: cane toads and black snakes in Australia. Proc. R. Soc. B 22 June 2006 vol. 273 no. 1593 1545-1550

http://www.animalcontrol.com.au/rabbit.htm

Global change affecting trophic interactions between plants and other interactions

Climate change influences trophic interactions. Drivers of global change (e.g. increased CO2 or nitrogen levels or invasions) can alter competitive interactions between different trophic levels. These drivers can perform effects on intensity of pathogen infection, herbivory, predation or they can be helpful for new invasive species (1).

Truth is that global change drivers could have some positive impacts on nature f.e. risen CO₂ or N levels can have positive effects for plant growth (2) or nectar production (3), but negative effects are probably more frequent. Example of negative effect could be competition of pollinator between native and alien plant (4, 5) or shift in timing of plant activities (in their phenology; 6,7). In first case native plant could not be pollinated because pollinator will prefer alien plant and in second case specific pollinator and pollinated plant have “bad timing” because pollinator will not be present at the time when plant is flowering. For pollination mutualisms could be also destructive land use and habitat fragmentation which can easily affect plants through loss of pollinator diversity (8).

Alien plant species could also alter fungal and microbial communities in soil (9) which could have an effect on N and P deposition or they can just overgrow native species because of lack of natural predators.

Global change drivers could also favour some species, for example C4 plants could grow in higher temperatures (9) which can then be more competetively successful, and they can also affect plant-herbivory interactions for example when CO₂ levels are increased, herbivore activity often decline (11). Alien plants can also support herbivores which have then higher reproductive capacity and they can more readily attack native species (12). Invasions of plants into new localities could alter either belowground biota, but in longer term also another (native) plants, like Myrica faya in Hawaii where this plant caused more than fourfold increase of soil nitrogen input and subsequent increase of ecosystem productivity (13).

Examples mentioned above shows either positive but also negative impacts of global change drivers on trophic interactions. Plant abundance is affected by both belowground and aboveground trophic level interactions. These species interactions will alter during climate change, and this will result that some species became rare or even extinct and some will became more abundant.

 

 

1 Tylianakis, J. M., Didham, R. K., Bascompte, J., & Wardle, D. A. (2008). Global change and species interactions in terrestrial ecosystems. Ecology letters, 11(12), 1351-1363.

2 Muñoz, A., Celedon-Neghme, C., Cavieres, L.A. & Arroyo, M.T.K. (2005). Bottom-up effects of nutrient availability on flower production, pollinator visitation, and seed output in a high-Andean shrub. Oecologia, 143, 126–135.

3 Davis, M.A. (2003b). Biotic globalization: does competition from introduced species threaten biodiversity? Bioscience, 53, 481–489.

4 Lopezaraiza-Mikel, M., Hayes, R., Whalley, M. & Memmott, J. (2007). The impact of an alien plant on a native plant–pollinator network: an experimental approach. Ecol. Lett., 10, 539–550.

5 Aizen, M.A., Morales, C.L. & Morales, J.M. (2008). Invasive mutualists erode native pollination webs. PLoS Biol., 6, e31.

6 Memmott, J., Craze, P.G., Waser, N.M. & Price, M.V. (2007). Global warming and the disruption of plant–pollinator interactions. Ecol. Lett., 10, 710–717

7 Cleland, E. E., Chuine, I., Menzel, A., Mooney, H. A., & Schwartz, M. D. (2007). Shifting plant phenology in response to global change. Trends in ecology & evolution, 22(7), 357-365.

8 Chacoff, N.P. & Aizen, M.A. (2006). Edge effects on flower-visiting insects in grapefruit plantations bordering premontane subtropical forest. J. Appl. Ecol., 43, 18–27.

9 Mummey, D.L. & Rillig, M.C. (2006). The invasive plant species Centaurea maculosa alters arbuscular mycorrhizal fungal communities in the field. Plant Soil, 288, 81–90.

10 Pringle, A., Adams, R. I., Cross, H. B., & Bruns, T. D. (2009). The ectomycorrhizal fungus Amanita phalloides was introduced and is expanding its range on the west coast of North America. Molecular Ecology, 18(5), 817-833.

11 Bezemer, T.M. & Jones, T.H. (1998). Plant–insect herbivore interactions in elevated atmospheric CO₂: quantitative analyses and guild effects. Oikos, 82, 212–222.

12 Rand, T.A. & Louda, S.M. (2004). Exotic weed invasion increases the susceptibility of native plants to attack by a biocontrol herbivore.Ecology, 85, 1548–1554

13 P. M. Vitousek, L. R. Walker, Ecol. Monogr. 59, 24(1989).   M. J. Swift, O. W. Heal, J. M. Anderson, Decompositio

 

 

Tomáš Figura

Are European orchids threatened by anorganic nitrogen -one of the main drivers of global change?

fig.1 oligotrophic canopy of P.albida, in albania distr. Tropoje         

           

fig.2 oligotrophic canopy of P.albida with local sheppard in Albania, Tropoje, 2nd Photo by Jaroslav Vojta

 

A quarter of species of the second world biggest plant family – Orchidaceae is at risk of extinction. This could be caused due to smuggling, habitat loss and impact of climate change (1). Orchids have specific physiology, and many researchers have been studying them in last decades either due to their commercial production, their loss from nature or their specific biology. One of their specific trait is that they have minute seeds, almost without nutrients, and they germinate only under specific conditions. Many species are cultivated for commercial or research purposes but some species have never been germinated in conditions in vitro (or in situ), and we do not know why they are not growing. This was the case of Pseudorchis albida, which is and not just according to our study (2), extremely strongly inhibited by inorganic nitrogen. P.albida will not grow when there is even very low concentration of inorganic nitrogen in substrate (2 mg of No3 per liter of growing media).

In Europe, concentrations of anorganic nitrate in soil are between 0.1 – 100 mg/l NO3 (3, 4, 5), and globally N levels are rising. When we look at hygienic limit for concentration of nitrates in tap water in EU, it is 50 mg/l, and this concentration is sometimes reached, or even exceeded. The real data shows e.g. 37,6 and 19,2 mg per liter for Prague (6). But when we look into other sources (7) we can see that the concentration of nitrates in most European water sources is already above 100 mg/l. According to this we can conclude that this species will not grow when watered with tap water from almost all European water sources, because just concentration of 50 mg/l of nitrates inhibits germination 44 times and when sowed on concentration 100 mg/l this species is not growing at all ! (2)

This specific inhibition on seed germination and subsequent growth is not specific just for Pseudorchis albida, but we found similar extremely strong inhibition also on many other orchid species, which are evolutionary or ecologically common to Pseudorchis albida and also some effect on species Orthilia secunda, which belongs to Ericaceae family (yet unpublished data).

We can just speculate why those plants have this inhibition or where is the evolutionary purpose of this inhibitory effect; it could be some mechanism which is protecting the seed from germinating on places which are rich on inorganic nitrogen, and therefore place like this could be easily inhabited by expansive or/and ruderal species, and subsequently that place would not be suitable for growing of an orchid. However it is obvious that many orchid species are disappearing from nature and it looks like that some of them probably just due to the nitrogen – one of the main drivers of global change.

Important information which we should keep in our minds is that because of increased use of fertilizers, there is very steep increase of nitrogen levels in nature in last years (f.e. 8) and one of bad consequences of this could be potential loss of some orchids from nature. This can happen really quickly and even before we find out how to save those species at least using in vitro/in situ cultivation.

 

fig.3.: mycoheterotrophic protocorm of P. albida

 

1 Swarts, N.D., Dixon, K.W.: Terrestrial orchid conservation in the age of extinction. – Ann. Bot. 104: 543-556, 2009.

2 Ponert, J., Figura, T., Vosolsobe, S., Lipavska, H., Vohnik, M., & Jersakova, J. (2013). Asymbiotic germination of mature seeds and protocorm development of Pseudorchis albida (Orchidaceae) are inhibited by nitrates even at extremely low concentrations. Botany

3 Callesen, I., Raulund-Rasmussen, K., Gundersen, P., and Stryhn, H. 1999. Nitrate

concentrations in soil solutions below Danish forests. For. Ecol. Manage.

114(1): 71–82.

4 Fetter, J.C., Brown, R.N., Görres, J.H., Lee, C., and Amador, J.A. 2012. Nitrate and

phosphate leaching under turfgrass fertilized with a squid-based organic

fertilizer. Water Air Soil Pollut. 223(4)

5 Pedersen, A., Petersen, B.M., Eriksen, J., Hansen, S., and Jensen, L.S. 2007. A

model simulation analysis of soil nitrate concentrations — Does soil organic

matter pool structure or catch crop growth parameters matter most? Ecol.

Modell. 205(1-2)

6 http://www.pvk.cz/res/data/001/000205.pdf?seek=2

7 Commision of the europaean communities (2007):Comission staff working

dokument: Accompanying document to the Report to the commission to the council and the europaean parliament on implementation of Council Directive 91/676/EEC concerning the protection of waters against pollution caused by nitrates from agricultural sources for the period 2000-2003 COM (2007) 120 final

8 Tilman, D., Fargione, J., Wolff, B., D’Antonio, C., Dobson, A., Howarth, R., … & Swackhamer, D. (2001). Forecasting agriculturally driven global environmental change. Science, 292(5515), 281-284.

 

Tomáš Figura

How does global change affect trophic interactions between plants and pollinators?

Trophic interactions are complex

A basic principle of trophic interactions is that all species are affected by other species, in one way or another. Trophic interactions are complex and are therefore difficult to study. In high-school biology books, examples of trophic interactions are simplified, and often limited to two-trophic levels. For instance, hawk eats mice, or lynx eats hare. Many would be surprised that the abundance of fish in a mountain lake could affect the abundance of pollinators, that in turn affect plant crops. A decline in the abundance of fish in the lake could lead to more larval dragonfly, and dragonflies predate on pollinators.These multi-trophic interactions are clearly challenging to study. This is one example that illustrates why conserving biodiversity is important, and something everyone should be concerned with. Trophic interactions are so complex, and local extinction or decline in abundance of one species can have unknown consequences.

 

Global changes affect plant-pollinator interactions

Pollination is a mutualistic interaction in which both the pollinator and the plant benefit from the interaction. The pollinator ensures seed-dispersal for the plant, and the plant provides the pollinator with nectar. In other words, pollinators play an important role in ecosystem functions. In addition, pollinators are providers of ecosystem services important to humanity.

The decline in pollinator populations and species has been a hot topic. In my opinion this is largely because of convincing numbers that illustrate the great economical value of pollinators pollinating crops and providing food for humanity. The rapidly changing species distribution of pollinators is concerning. Current global changes impose several threats to pollinators, and there is no denying that human activity is largely to blame. Habitat change, invasive species and climate change have increased the risk of pollinator and plant species going extinct, locally or globally [1].

When speaking of global change in regards to ecology, one usually thinks of climate change. Climate change has been shown to affect phenological events, such as flowering in plants, and the first flight of pollinators [2].There is a tendency that pollinators start their activity earlier in the season than plants. This could cause a mismatch situation where pollinators start their activity before the plants are ready for them, and thereby limiting the opportunity for interaction between them [3].

Climate change may affect species directly, but also indirectly [2]. In addition, trophic partners can become disconnected because they may respond differently to global changes, such as climate change. The mismatch can be both spatial (distributional) and temporal (phenological) [2], however, there is much we do not know as the consequences of mismatches have not been thoroughly studied.

 

 

Invasive species can disrupt existing plant-pollinator interactions

The introduction of new species can affect the trophic interactions. In fact, studies have shown that the presence of an invasive plant species can affect pollinators fidelity and preference to native plants [4]. This could affect the reproductive success of the native plant.It is difficult to predict the consequences. A case study indicated that pollinators will not necessarily prefer an invasive species that has a larger, showier floral display [4]. Another factor that must be taken into consideration is that the interactions can change over the course of an invasion.

 

Why should we bother?

First of all, biodiversity is in my opinion a good enough argument on its own. However, politicians are concerned with economics and numbers. Perhaps it is wise to focus on the arguments that will get their attention, and hopefully convince them to consider how their political decisions can affect biodiversity. Some might argue that focusing on ecosystem services rather than biodiversity being valuable in itself may lead to exploitation or ignoring conservation of species that are in danger of extinction, because they do not provide a significant ecosystem service. However, an important argument in my opinion is that we do not know enough about possible ecosystem services, therefore everyone should be interested in conserving biodiversity.

We may not be able to counteract global warming soon enough for the pollinators’ sake, but we can try to reduce the pressure on them. Habitat change has been declared as the greatest threat to biodiversity and the main reason why species go locally and globally extinct. Maybe this is where we should start.

 

 

 

References

2. Hegland, S. J., Nielsen, A., Lázaro, A., Bjerknes, A.-L. and Totland, Ø. (2009), How does climate warming affect plant-pollinator interactions?. Ecology Letters, 12: 184–195. doi: 10.1111/j.1461-0248.2008.01269.x

3. Memmott, J., Craze, P. G., Waser, N. M. and Price, M. V. (2007), Global warming and the disruption of plant–pollinator interactions. Ecology Letters, 10: 710–717. doi: 10.1111/j.1461-0248.2007.01061.x

4. King, V.M, Sargent, R.D., Presence of an invasive plant species alters pollinator visitation to a native, Accepted: 8 February 2012 Springer Science+Business Media B.V. 2012. Biol Invasions. doi: 10.1007/s10530-012-0191-3

 

All Strangers are not foes

Conservation writer Emma Marris points that many ecologists and conservationists are prejudiced towards non-native species and preoccupied with the ‘native good and non-native bad’ dogma [1]. ‘non-native bad’ notion has much been influenced by philosophical standpoint regarding ‘nature’ and ‘natural’ and also by some overwhelmimg facts associated with some non-native species which have invaded new areas. An anlysis by Davis wilclove shows that Invasive Alien Species (IAS) is the second largest threat to bidiversity in the United states [2]. Much popular ‘IUCN Red List of Threaned species’ also points that IAS is a major cause of species threat and extinctions particularly of birds, fishes and mammals [3]. Many birds and mammals in oceanic islands have already been wiped out by feral species introduced intentionally or accidently. Brown tree snake on Guam-which eradicated 15 native birds, or the Nile Pearch-which caused extinction of 200 fish epitomises non-native species for many. Ecologists are worried that complex and heterogenous ecosystems are turning towards simple and monotonous with increased non-native species.

Of course, introduced species which turned themselves into invasive are real environmental and economic burden and they deserve management intervention, however, considering all non-natives as negetive appers too simple generalization. Management of invasive species is much influenced by native versus non-native dichotomy as pinted by Mark Davis [4].

‘non-native’ species have been vilified for driving beloved ‘native’ species to extinction and generally polluting ‘natural’ environ­ments. Such characteri­zations have helped to create a pervasive bias against alien species that has been embraced by the public, conservationists….….. throughout the world.

It seems that ‘non-native species bad’ has been taken for granted by many policy makers and ecologists which creates bias towards non-natives. Here, I attempt to show that all non-natives are not bad rather they play role in conservation and restoration. And argue native non-native dichotomy largely overlooks social and ecolgical contribution of non-native species.

Ecologists have documented cases where introduced species have played substantial role to enhance biodiversity. Ascension island in the Atlantic-once considered as very poor by Darwin when he visited almsot 200 years ago- now is substantially richer in biodiversity compred to Darwin’s time. Now the area has been forested, species diversiy has manifolded-only one native tree has been accompained by 39 guest tree species [1]. Dov sax published a much counterintuitive result from a mata-anlysis ivolving all the oceanic islands aross the globe[5]. In the islands species brought by human have outnumbered the extinctin and the richness is higher than that would be in absence of introduction by humans. Ariel Lugo in Puerto Rico found that introduced tree plantation performed better in species diversity, biomass accumulaion and nutrient cycling than the native forests [6]. Similarly, a study comparing plant species richness between introduced and native pine forest in islands of western coast of norway reports higher richness in nn-native plantatins [7]. There are several instances where non-native species have supported and conserved native species by providing food and shelter, conserved rare species and substituted extant taxa [8].

But all biologists and ecologists can not enertain the ‘high biodiversity’ and restored ecosystems that contain non-native species. Instead of getting appreciation for their role in conserving other species and maintining diversity those species are getting an axe from environmental managers simply because they were originated somewhere else. Here ‘non-native bad/unnatural’ notion plays to rejection of diversity by nn-natives.

Contrary to ‘non-native bad’ generalization, there are several instances where non native species have played role in restoring the degraded ecosystems. US forest service scientist John Ewel opion that we can consider non-native species in restoration provided they do not pose serious threat to ecosystem health and provide social and ecological services [9]. Ariel Lugo based on his long term research at Puerto Rico concludes [6]:

The invasion of a site and the formation of an alien dominated forest serve important ecological functions, such as repairing soil structure and fertility, and restoring forest cover and biodiversity at degraded sites.

Pinus patula?, a native of mexican highlands brought to Nepal by Australian foresters has been successfully been used to restore degraded forest in hills of Nepal. This species made ground to regenerate native species. Now native broadleaved species are regenerating luxuriantly under the crown of non-native species.

Most of the extinction of native species particularly birds in ocenic islands is resulted from intertrophic interaction- by predation rather than competition. There are very rare instances of extincation in which introduced plant species is attributable culprit. Plant species do not predate but they may pose threat by altering habiat [10]. Therefore, categorically blaming non-native as cause of extincation is also biased.

Movement of species is pervasive and continous, we accept non-natives in fields, avenue plantations and cityscapes. It is likely that more species will move from one parts of world to other to meet aesthetic and economic needs. Eucalypts and mahogany for timber and cherries for urban beauty are accepted away from their origin. During remote past propagules of species might have transported far away from their historic ranges by storm, floods and birds. Species will move towards cooler places to respond global warming. Currently there are translocations of wildlife to save small population crashing. There are attempt even to introduce wildlife as proxy of extant species [1]. These continous flux of species questions the way non-natives are defined. Who knows, species capable of surviving in new environment may best fit in future climate and land use scenarios.

Spread of non-native species has became common phenomenon, definitely not an exception. Public, plicy makers and scientists should admit that environmenal threat has been posed by a small subset of non-native species. Judging species based on ‘what economic and ecological roles they play in new ecosystems’ may be more smart over judgement based on ‘where they originated’ [4, 11]. Native non-native dichotomy should be abandoned and and new classification of species based on their damage to ecosystem health and biodiversity may help manage non-native based on their ecological and economic roles.

References

1. Marris E. 2011. Rambunctious GardenWilcove DS. 1997. Bioscience:
2. Wilcove DS et al 1997. Bioscience 48(8):607-615
3. IUCN 2004 IUCN Red List of Threatened Species.
4. Davis MA et al.2011. Nature 474:153–154
5. Sax DF. 2004. The American Naturalist. 160(6): 766-783
6. Lugo AE 2004. Frnt Ecol Env. 2(5): 265–273
7. Vetaas OR et al 2013. ?:1-13.
8. Schlaepfer MA et al. 2011. Conservation Biology 25(3): 428-437
9. Ewel JJ, Putz FE. 2004. Front Ecol Environ 2(7): 354–360
10. Davis MA 2003. Bioscience 53(5): 481-489
11. Warren CR 2007. Progress in Human Geography 31(4): 427–446

Lila Nath Sharma

The ivory gull, a high-Arctic specialist

by Vegard Finset Fjeldheim

The polar bear is by many regarded as the symbol of the Arctic. White and majestic, and very well adapted to its environment With Snowy Mountains and ice covered fjords. However, the polar bear is not the only animal that depends on the sea ice. The ivory gull is a high-Arctic seabird species, and the only bird associated with sea ice throughout the year [1, 2], It is pure white, with black legs and dark eyes, as shown in Figure 1 and 3 [3]. The ivory gull nest in colonies, sparsely distributed in the northern areas of Canada, Greenland, Norway (Svalbard) and western parts of Russia [1].It has a wide variety of food sources, primarily foraging on polar cod and crustaceans, but also human waste, carrions killed by polar bear and excrements and placenta etc. from marine animals [1]. Observations of the ivory gull, e. g. Inuit communities, indicated that the population was declining, and a study done by Canadian scientist showed a 80 % decline in numbers of nestling gulls in Arctic Canada [4]. What might be the reason for this declination, and do humans somehow contribute to it?

 

 

 

 

 

 

Figure 1. An ivory gull in a nestling colony at Spitsbergen, Svalbard.

It is believed that the ivory gull finds most of its pray close the the ice edge. By attaching small satellite transmitters to ivory gulls from Canadian islands, scientists has been able to monitor their movement during the year [5]. The monitored gulls rarely traveled over open waters free of ice, but tended to remain close to pack ice- and ice floe edges throughout the winter. The areas around Davis Strait and the Labrador Sea was found to important wintering areas for the ivory gull, most likely because these areas provide a predictable food supply along the pack ice edge. These areas are also found to be an important wintering destination for the nestling gulls in Svalbard and Russia [6]. The study also found that the individuals vary greatly in migration routs and timing, most likely due to the gulls affinity to the sea ice and their apparent avoidance of open water. The sea ice formation and extent in the fall vary from year to year, and the ivory gull will choose the migration route with the best foraging opportunities. With warmer temperatures, both in the ocean and atmosphere, the extent and timing of sea ice formation is changing and highly affecting the ivory gulls foraging opportunities, see Figure 2. Warmer ocean temperatures do not only have an impact on the sea ice, but might also alter the distribution of the gulls pray in the water masses [5].

 

(a)                                       (b)

Figure 2. (a) show trends in the mean annual surface temperature from 1960-2011. The highest increase in temperature is found in the Arctic [11]. (b) show average monthly Arctic sea ice extent, with a blue trend line, in September, when the sea ice has its minimum extent [12].

The Arctic is not a clean area unaffected by human activity, but contaminants from the industrialized world is transported to the Arctic by various routes such as oceanic and atmospheric transport [7]. Here, the contaminants are easily incorporated in the Arctic ecosystems. Arctic animals can store large amount of fat for insulation and energy supply when food becomes sparsely [8]. Persistent organic pollutants (POPs) are one type of contaminants transported to the Arctic, and stored in the organism body fat when taken up in the biological system. Since the organisms have no efficient detoxification of such pollutants, it is stored and passed on to the next generation or next organism in the food chain if it is eaten. [2, 9], This means that animals situated high in the food chain may accumulate high levels of these contaminants. The ivory gull, that have polar cod and seal residues in its menu, have a high position in the Arctic food chain. To figure out the level of contaminants in ivory gulls, eggs collected from the Russian and Norwegian Arctic were analyzed [2]. They found that fat soluble organoclochlorines, including PCBs and DDE (a product from decomposition of DDT), dominated the contaminant profile, and the level was among the highest ever reported in Arctic seabirds. As noted in the article, the levels are lower than in eggs from birds of pray and gulls in the 1960s and 1970s in temperate areas when the use of these substances were not regulated, but local sources of emission in the Arctic are still relatively few. The effects of these pollutions are not very well known for the ivory gulls, but it is believed to have a negative long-term effect in the reproductive success. This is mainly based on other studies of seabirds at the top of the Arctic food chain that have shown reproductive, developmental, behavioral and immunological effects with even lover levels of contaminants than found in the ivory gull.

At The International Union for Conservation of Nature and Nature Resources’ (IUCN) Red List of Threatened species, the ivory gull is classified as near threatened with global warming and pollution as major threats [10]. And sadly, the gull is not itself responsible for these changes. It is believed that human activity has a large impact in the global warming we now are facing, and humans are for sure responsible for the pollutant found in ivory gulls and other species in the high-Arctic. On top of this, it is also believed that hunting of ivory gulls, mainly along the cost of Greenland, is a contributing factor to the declination, but the scope of this is not well known [1].

Figure 3. Will this be an even more rare sight in the future?

While we humans sit here in the «south» and live our normal lives, the price of this is paid among others by the ivory gulls and other high-Arctic animals. Our use of chemicals and increased emissions of climate gasses are effecting an changing the Arctic ecosystems and hence the habitat preferences of the ivory gull. How the ivory gull will deal with the declines of extent and duration of sea ice, and the consequences of this, is still not known, but the ivory gull is an ideal bioindicator of the effects of the global warming due to its proximity to the sea ice. To conclude, the ivory gull might be an Arctic climate refugee forced to flee by human activities.

References:

[1] Hallvard Strøm. Ismåken-en arktisk klimaflyktning? Vår Fuglefauna, 30:108–114, 2007.

[2] C. Miljeteig, H. Strøm, M. V. Gavrilo, A. Volkov, B. M. Jenssen, and G. W. Gabrielsen. High levels of contaminants in ivory gull Pagophila eburnea eggs from the russian and norwegian arctic. Enviromental Science & Technology, 40(14):5521–5529, 2009.

[3] Hallvard Strøm. Svalbards fugler. In K. M. Kovacs and C. Lydersen, editors, Svalbards fugler og pattedyr, pages 151–154.Norsk Polarinstitutt, polarhåndbok, 13 edition, 2006.

[4] H. G. Gilchrist and M. L.Mallory. Declines in abundance and distribution of the ivory gull (Pagophila eburnea) in arctic canada. Biological Conservation, 121:303–309, 2005.

[5] N. C. Spencer, H. G. Gilchrist, and M. L.Mallory. Annual movement patterns of endangered ivory gulls: The importance of sea ice. PLoS ONE, 9(12), 2014. doi:10.1371/journal.pone.0115231.

[6] O. Gilg, H. Strøm, A. Aebischer, M. V. Gavrilo, A. E. Volkov, C. Miljeteig, and B. Sabard. Post-breeding movements of northeast atlantic ivory gull Pagophila eburnea populations. Journal of Avian Biology, 41:532–542, 2010. doi:19.1111/j.1600-048x.2010.05125.x.

[7] I. C. Burkow and R. Kallenborn. Sources and transport of persistent pollutants to the arctic. Toxicol. Lett., 112:87–92, 2000.

[8] Pål Prestrud. Adaptions by the arctic fox (Alopex lagopus) to the polar winter. Arctic, 44(2):132–138, 1991.

[9] Samuel C. Byrne. Persistent organic pollutians in the Arctic. A Report for the Delegates of the 4th Conference of the Parties Stockholm Convention on Persistent Organic Pollutants, 2009

[10] The IUCN Red List of Threatened Species. Pagophila eburnea. Version 3, 2014. <www.iucnredlist.org>. Downloaded on 19 February 2015.

[11] National Snow & Ice Data Center. Climate Change in the Arctic <https://nsidc.org/cryosphere/arctic-meteorology/climate_change.html> Downloaded on 19 February 2015.

[12] National Snow & Ice Data Center. Poles apart: A record-breaking summer and winter <http://nsidc.org/arcticseaicenews/2012/10/poles-apart-a-record-breaking-summer-and-winter/> Downloaded 19 February 2015.

 

Climate-driven shifts in plant species along the elevation gradient: Are we close enough to the facts?

Upsetting climate trends

The 21^st century has witnessed the alarming signals of anthropogenic global climate change particularly in the high altitude/latitude regions of the world. This is indicated by the trend showing a rise in global temperatures by almost 0.85 °C over the past 130 years [1]. Regional trends of climate warming are rather distressing. The Himalaya for instance has experienced an increase of 1.5^oC during the past 25 years (1982-2006) [2].

 

Observed impacts

Evidence so far reveals the rapid changes in geographical distribution of several plant species and habitat types across the globe, especially in the mountain regions, as the fingerprints of anthropogenic climate – and/or land-use – change [3]. However, precise quantification of these changes is a big challenge due to complex interactions of their drivers [3], methodological inconsistencies in analysing the species’ responses [4], and unavailability of detailed data [5].

Conceptually, the warming climate has left only three options for the earth’s biota: to shift towards newly suitable geographic locations , to adapt to a new environment , or to die , or some combination of these responses [6]. Elevation is considered a proxy for temperature because atmospheric temperature decreases with an increase in elevation and the realized ecological niche (environmental space within which a species maintains itself in presence of other species) of plant species mostly remain unchanged at least for thousands of years [7]. Therefore, in response to a warmer climate, plant species are expected to shift upslope to the cooler areas to compensate for the increased temperature; whereas those living at extremes of the elevation gradient may undergo extinction. Many authors [8-13] have attributed the upslope or poleward shifts in the range or abundance of plant species to the increase in atmospheric temperature during recent decades. However, there is enormous debate regarding the severity and frequency of these changes at different scales.

 

Lack of consensus

Methodological inconsistencies

To date, assessments of climate-driven distributional changes of species have largely been based on niche-based models. Since these models ignore species’ demography, adaptive potential and biotic interactions, they often tend to predict higher rates of extinction or distributional changes, leading to higher uncertainties [14, 15]. However, the assumption of niche-based models that the intact plant community responds in a similar fashion to the warming climate is unlikely because realized niche and biotic interactions vary greatly among the species of a community [16]. Therefore, a consistent widespread pattern of upward shifts of the species and their assemblages in response to a warmer climate cannot be expected.

The process-based models additionally include the factors responsible for range dynamics such as seedling dispersal, population dynamics, biotic interactions, eco-physiological factors, and the potential persistence of species under deteriorating conditions [14]. However, such models are scarce at the continental scale because these are applicable only to well-known species for which demography or physiology has been studied for a long time.

Other factors: land-use matters !

Several factors other than the changing climate, such as increased deposition of atmospheric nitrogen, dispersal lag in species colonization, changes in moisture regime, highly responsive species pool, and biotic interactions, have also been proposed for the observed upward shift of the plant species along the elevation gradient [see [5]].

Species’ responses observed in several regions are not straightforward as estimated earlier by the niche-based models. In the European mountain summits, the amount of change in species assemblages is found to be unrelated to the amount of climate warming [5]; whereas no shifts or unexpected downward shifts in species’ ranges have been  observed in other regions [17]. Similarly, the downslope retreat of the treeline in Himalaya and Tibetan Plateau is reported as due to the changed precipitation regime rather than the warmer temperature [18]. For several plant species and their assemblages, climatic responses lag behind the degree of temperature increase [16]. For instance, ‘thermophilization’ of plant species in temperate forests of some regions often lags behind warming. Densified forest canopy cover of the forests due to a change in the land-use regime has buffered the effect of regional climate warming via microclimate cooling. The forecasts of climate-related range shifts are thus modified by change in forest cover [19]. Analysing the distributional shifts with a focus on temperature alone might be potentially misleading due to the confounding role of other factors such as precipitation and land-use change [5].

Data-gaps enhancing uncertainties

Most of the low-elevation mountain areas are densely populated; where land-use change often has robust effects on plant communities. However, observations of climate and land-use driven plant community change in lower mountain forests are scarce in comparison to those in high-elevation ecosystems [5, 17]. Studies on climate driven vegetation changes from the biologically more diverse Asian region also remain very scarce; and ecophysiological and cytogenetic data on populations of species are in addition seriously limited [20].

 

Way forward

Analysis of climatic responses of biotic communities is critical for assessing species’ extinction risks and to formulate effective conservation measures. Realistic assessment of climate-driven geographical shifts urgently requires improved monitoring at different scales, and then attributing the observed changes to climatic variables integrated with the non-climatic, ecophysiological, and genetic factors of the species. It is critically important to develop several niche-based as well as process-based models for the same species under the same scenarios and scales, and compare their predictions in order to identify robust results.

 

References

1. IPCC, Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, T.F. Stocker, et al., Editors. 2013, Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 1535 pp.
2. Shrestha, U.B., et al., Widespread Climate Change in the Himalayas and Associated Changes in Local Ecosystems. PLoS ONE 2012. 7(5): p. e36741. doi:10.1371/journal.pone.0036741.
3. MEA, Ecosystems and Human Well-being: Biodiversity Synthesis.World Resources Institute, Washington, DC. 2005.
4. Dawson, T.P., et al., Beyond Predictions: Biodiversity Conservation in a Changing Climate. Science, 2011. 332(6025): p. 53-58.
5. Grytnes, J.-A., et al., Identifying the driving factors behind observed elevational range shifts on European mountains. Global Ecology and Biogeography. DOI: 10.1111/geb.12170, 2014.
6. Lenoir, J. and J.-C. Svenning, Latitudinal and Elevational Range Shifts under Contemporary Climate Change. Encyclopedia of Biodiversity, 2013. 4: p. 599-611.
7. Peterson, A.T., Ecological niche conservatism: a time-structured review of evidence. Journal of Biogeography, 2011. 38(5): p. 817-827.
8. Thuiller, W., et al., Climate change threats to plant diversity in Europe. Proceedings of the National Academy of Sciences of the United States of America, 2005. 102(23): p. 8245-8250.
9. Pauli, H., et al., Signals of range expansions and contractions of vascular plants in the high Alps: observations (1994–2004) at the GLORIA*master site Schrankogel, Tyrol, Austria. Global Change Biology, 2007. 13: p. 147–156.
10. Lenoir, J., et al., A Significant Upward Shift in Plant Species Optimum Elevation During the 20th Century. Science, 2008. 320(5884): p. 1768-1771.
11. Chen, I.-C., et al., Rapid Range Shifts of Species Associated with High Levels of Climate Warming. Science, 2011. 333(6045): p. 1024-1026.
12. Pauli, H., et al., Recent plant diversity changes on Europe’s mountain summits. Science, 2012. 336(6079): p. 353-5.
13. Gottfried, M., et al., Continent-wide response of mountain vegetation to climate change. Nature Climate Change, 2012. 2(2): p. 111-115.
14. Morin, X. and W. Thuiller, Comparing niche- and process-based models to reduce prediction uncertainty in species range shifts under climate change. Ecology, 2009. 90(5): p. 1301-1313.
15. Hampe, A., Bioclimate envelope models: what they detect and what they hide. Global Ecology and Biogeography, 2004. 13: p. 469–476.
16. Bertrand, R., et al., Changes in plant community composition lag behind climate warming in lowland forests. Nature, 2011. 479(7374): p. 517-520.
17. Lenoir, J., et al., Going against the flow: potential mechanisms for unexpected downslope range shifts in a warming climate. Ecography, 2010. 33(2): p. 295-303.
18. www.scientificamerican.com/article/high-altitude-forests-in-the-himalayas-harder-hit-by-droughts/?print=true.
19. De Frenne, P., et al., Microclimate moderates plant responses to macroclimate warming. Proceedings of the National Academy of Sciences, 2013.
20. Parmesan, C., Ecological and Evolutionary Responses to Recent Climate Change. Annual Review of Ecology, Evolution, and Systematics, 2006. 37(1): p. 637-669.

 

Kuber P. Bhatta

«The man on the street»

What do the man on the street know about global warming and what kind of arguments do the scientist give us about this subject? This is in short terms what I want to discuss in this paper. First I want to present some of the evidence scientist use when they discuss global warming and the human impact. Then I will present some of the counter arguments skeptics’ use against the knowledge presented.

How much do people know about global warming? This is not an easy question to answer, and the answer will probably differ a lot from person to person. One thing a lot of people have in common is that they all care about the weather! Already in 2015, Norway has had some of the most extreme storms and temperature variability’s people have ever experienced, and it is only February. The sad thing is that storms and unstable weather are becoming more frequent all over the globe. How often don’t we hear about storm, hurricanes, droughts and flood in the news? One way to explain this is; the globe is changing! But what is changing?

The first and most obvious argument is the globe is getting warmer, global warming. This is often the first thing people mention when they are to discuss global warming. It is documented that the temperature has increased, and the scientists have evidence to support this observation. Since the 1850 the average temperature has increased by 0.85 degrees Celsius (IPCC Fifth Assessment Report: CSIROexperts comment. (2013)). In IPCC Fifth Assessment Report they present two main findings: 1) There is no doubt that Earth is warming. 2) It is extremely likely that more than half of warming over the last 60 years is due to human influence. The extreme likely is used in this report for the first time in 2013. They have over a series of years followed the development and they have now high confidence to believe it is due to human impact.

One example comes from Hawaii. In Hawaii, atmospheric CO₂ have been measured since the 1960s. What we can see from the graph below this section is that the amount of CO₂ in the atmosphere has grown from 320ppm(parts per million) in 1960 to 400ppm today. This isn’t just a linear increase, but an exponential increase, and that is devastating news. The net uptake of CO₂ in the ocean and in the forests is 27% respectively. The remaining 45% goes into the atmosphere. This basically comes from fossil fuels and deforestation in the rainforest. That is almost 1000 tons per second! (Tore Furevik, the Centre for Climate Research University of Bergen).

 

 

 

 

 

 

 

 

 

 

 

 

Figure.1: The figure shows the global carbon budget. (from the lecture notes by Tore Furevik).

Figure.2: The figure shows the linear increase of CO2 in the atmosphere, taken in Hawaii (from the lecture notes by Tore Furevik).

 

How can the “man on the street” notice this increase in ppm (parts per million)? The “man on the street” cannot notice the parts per million, but they can notice the increase in temperature. Temperature rise is the result of what I have presented here with the increase in ppt, and that is what people experience physically. The people who are sceptic towards global warming may not trust the collecting data of these observations. In regard to the temperature increase, they argue and believe the records of the temperatures are unreliable and that they exaggerate the amount of warming due to the “urban heat island” effect. With the Urban heat Island they think about the location of record stations. The measurements are often taken at ground levels, in cities and towns(Totty, 2006). It is true that the stations are on Earth level, but the results presented are collected from all over the planet and converted into one statistic. The fact that the increase in temperature high up in the atmosphere is not significantly bigger does not change the overall trends that indicate global warming(Totty, 2006).

Other evidence people in the north can relate to in understanding and accepting global warming is the amount of precipitation we experience in a year, month or even a week in the most extreme areas. It is actually here in the Northern Hemisphere we find the biggest changes in temperature and precipitation. This is due to the fact that we have a lot more continents in the north. With the large, dark areas now being exposed due to the melting of glaciers and ice coverage, the continents have a larger impact than what the ocean have. The following graph displays the measurements taken in the last decade of temperature and precipitation. In IPCC Fifth Assessment Report (2013) they present the observations of temperature change and precipitation change with high confidence. Again, sceptics can argue that natural factors can be enough to account for this modern warming from the 1900^th. Scientists can relate to the fact that solar energy and natural changes can have quite an impact on the world’s climate. But then again, the natural factors aren’t enough to account for the sharp increase in temperatures and precipitation since the late 1970 as we see here (Totty, 2006).

 

Figure.3: The two graphs show how the annual amounts of precipitation and temperature in Norway have changes since 1900. (from the lecture notes by Tore Furevik).

One of the biggest challenges climate change has today is the amount of CO₂ emission from the industry. We can discuss what to do with this forever. Scientists can present evidence, but they can just do so much. In the end, it is the politicians that have to find some common ground to develop strategies that can save the planet. Lets hope they find this in The United Nations Climate Change Conference in Paris this year.

 

 

References

TOTTY, M. 2006. What Global Warming. The Wall Street Journal, 6. December 2009[Internett] Tilgjengelig fra: <http://www.wsj.com/articles/SB10001424052748703819904574551303527570212>[Lest 6.februar 2015]

Lecture notes from Professor Tore Furevik Bjerknes from the Centre for Climate Research University of Bergen