How non human species adapt to climatic changes

Introduction

This unit explores the effects of anthropogenic climate change on non-human species. It explores examples of the way that different non-human species adapt to climate change. It uses basic ideas in ecology to examine how species will, and already are, adapting to changing climates. Finally, it looks at how these adaptations will affect biodiversity within the UK.

Unit authored by Ronald Macintyre

Learning outcomes

By the end of this unit you should be able to understand:

• key terms in ecology;

• how non-human species adapt to climate change;

• the link between climate change and loss of biodiversity;

• the effects that climate change will have on species diversity within the UK.

1 How mobile species adapt to climate change

1.1 Outline

This unit explores the effects that changes in climate have on the distribution and biodiversity of non-human species within the UK. In this section I will introduce the term biodiversity and look at species distribution. We will explore the effects of changing climate on the migration patterns of bird species and begin to look at how changing climate affects the timing of biological events (phenology) and changing patterns of distribution.

Before we begin I would like to say something about why I am using the term non-human species within this unit.

Much of the discussion on climate change focuses on what climate change will mean for us. This unit tries to redress that imbalance, albeit in a very small way. The focus on, and the use of the term, non-human species is an attempt to highlight the separation we make between the human and the non-human. This attempt relates in part to a desire that debates on climate change address the effects on all species and in part it relates to the idea of value and, in particular, how we value nature.

1.2 Phenology

Phenology is the study of when a recurring natural phenomenon takes place. For example, your first sighting of frog spawn or a snowdrop, or when the berries come on a mountain ash. The arrival and departure of migratory species to and from the UK, in particular birds, is an important ecological (and perhaps cultural) marker of seasonal change.

Those interested in learning more about phenology and getting involved in it should refer to the UK Phenology Network and the Open University's iSpot programme.

1.3 Terminology

In this section we look at the effects that changing climatic conditions have on the migration patterns, abundance and distribution patterns of invertebrates, in particular butterflies. Like birds (and all living things), invertebrates are sensitive to changing climatic conditions. Here, we are going to look at why living things are sensitive to changes in environmental conditions.

Let's first look at some of the relevant terminology.

Different species are able to use or tolerate different types of environment – some can stand cold, some can stand hot – and eat different things; they each occupy slightly different ecological niches. Even within a species, individual organisms may well occupy slightly different niches – the town fox and the country fox. This is because they occupy different types of habitat. Some species are highly adaptable; for example, omnivorous rodents like the brown rat can survive on a wide range of foods over a wide range of climate conditions, as can be appreciated by looking at a map of the brown rat distribution.

Some organisms occupy very narrow and particular ecological niches. The range of habitats they occupy is limited, as they require particular environmental conditions – environment is understood as the interrelationship between the living (e.g. plants and animals) and non-living (geology and climate) of a particular place or set of places. A well-known example of an organism that needs a very specific set of environmental parameters to reproduce successfully is the giant panda.

As species extend their range north and begin to change their seasonal distribution, this changes the dynamics within the ecosystems they inhabit. An ecosystem is simply a collection of living things and the environment in which they live. It can be understood at a number of scales, from the rock pool to the North Sea. Different species can inhabit fairly similar ecological niches (e.g. use particular food plants) in which, as long as they live in slightly different habitats, they will not compete for resources. As environments change, habitats change, and this can lead to species migrating into new habitats. If, aside from the occasional periodic climate event, environments are relatively stable over time, or change very slowly, then species have time to adapt to those changing conditions. Rapid changes, like loss of habitat or changing environmental conditions, can lead to the disappearance of a species from an area (locally extinct), from the UK (national extinction) or even lead to species extinction.

2 Non-human species as indicators of environmental change

2.1 Birds

As we try to understand the relationship between climate and the distribution and diversity of non-human species, migratory birds are an important source of information for two reasons:

• the timing of arrival and departure in the UK seems to be closely correlated with seasonal changes in temperature

• large networks of well-informed people watch carefully for these arrival and departure events, so we have a lot of data about these events.

Let's look at a couple of examples.

Bird migrants to the UK and Europe are arriving earlier and earlier. If you look at the table on page 4 of the UK Phenology Network's spring 2009 report you can see the pattern for migrants like the house martin and the swift.

The timing of recurring events like migration or raising young is tied to variations in environmental conditions; for example, day length and temperature.

The British Trust for Ornithology (BTO) has extensive records on the timing of egg laying for many UK bird populations. Crick (2007) reports that, between 1971 and 1995, 51 of the 65 species studied showed a pattern of earlier egg laying. Most significantly, this was over a range of species from a number of families over a range of different ecosystems.

Phenology can be used as an indicator of changing environmental conditions. You can find out more information about the BTO programmes and other related organisations that help us get a better picture of how changing climatic conditions affect birds at the websites of the following:

• Euring, the European Union for Bird Ringing

• the BTO's Swallow Roost Project.

In addition to the changes in the timing of recurring natural phenomena, scientists have also begun to notice changes in migration patterns, including changes that relate to the distribution of migratory species and the duration of migrations.

Work by Gregory et al. (2009) indicates that changing climate may mean that the migration routes of spring arrivals like warblers may shift further north. This means a change in the distribution of species like the blackcap and the whitethroat. It also means that these birds will have longer and more difficult migration routes, potentially leading to a reduction in bird numbers.

An overview of this research can be found on the RSPB website.

One of the other things that the modelling by Gregory et al.(2009) tells us is about how changing climate might also effect the range and abundance of species within the UK and Europe, where ‘range’ is a term used to indicate the geographical area in which a species is normally found and ‘abundance’ is an estimate of the number of individuals.

While the Gregory et al. (2009) paper itself is necessarily complex, you can find a useful summary on the European Bird Census Council website. If you look at the graphs you will see that the models indicate that the range (or distribution) and populations of some species will drop, while the range and abundance of other species will increase. You will see that, of those that are predicted to rise, some are species normally found in the south of Europe, while some of those predicted to fall are found in the north of Europe. This is because (as noted in the example of the migratory warblers above) as temperatures rise, the range (or distribution) of species tends to extend northwards. This is good for species in the south of Europe; it is not so good for species in the north. I will look at examples of how this will affect species in the UK later in this unit.

For more background information, see the RSPB's ‘user-friendly’ report entitled ‘Climate change: wildlife and adaptation – 20 tough questions, 20 rough answers’.

2.2 Butterflies

It might seem surprising that an organism as apparently delicate as the butterfly might migrate, but it does.

Research on moths and butterflies in the south of England by Sparks et al. (2007) indicates that many more species from mainland Europe are now migrating to the UK, typically involving a 150 km journey. A clear link exists between temperature and increases in the number of moth species commonly found in mainland Europe being cited in the UK. Sparks et al. (2007) suggest that, for every 1°C rise in temperature in southwest Europe, the UK will attract about 14 new moth and butterfly species. In addition, many migrant butterfly and moth species are not overwintering in the UK.

For more information, see the Butterfly Conservation website.

The Environmental Change Network (ECN) has 57 monitoring sites throughout the UK. There is an interactive element to their website, which looks at the relationship between a limited number of species and different environmental parameters.

2.3 Beetles

Here, I want to look at the distribution of beetles, in particular the carnivorous Carabidae.

What researchers at the ECN found is that rising temperatures seem to be affecting different populations of beetles in different parts of the country in very different ways. The trend is for an increase in carabid numbers in the lowlands, the south and the east, and a decrease in population in other monitoring sites – in particular in the uplands and the north. The researchers noted that temperature increases in the northern sites were relatively more pronounced. They also noted that northern and upland species may be much more sensitive to changes in temperature.

For more information on this and information on a range of other organisms, see the 2009 ECN report.

3 Loss of biodiversity and extinction

3.1 Birds

So far, we have looked at examples of species that the UK will ‘gain’ from mainland Europe. In this section we will look at the species we may lose as a result of changing climate. Some of these species, like the ptarmigan and black grouse, are widespread throughout upland and sub-Arctic regions within Europe. Some of these are endemic, like the Scottish crossbill.

Researchers suggest that for some species of upland birds, like the red grouse, changes in climate will mean a reduction in breeding areas and in population and a contraction in range as habitats change – see ‘Birds on the move’.

For other species that are already breeding at or near the edge of their habitat (like the black grouse and capercaillie) the loss of suitable habitat, or the geography of the habitat (already found in the highest peaks in the UK), may leave the species vulnerable to extinction within the UK. This illustrates how species are vulnerable to changing environmental conditions when they are at the edge of their niche or where the habitat is marginal.

You can find distribution maps for a range of European bird species at the European Bird Census Council.

3.2 The relevance of longitude, latitude and altitude

The examples we have looked at so far have alluded to a relationship between the range of a species and changing environmental conditions associated with changing geography, particularly latitude (movements of species south and north). Longitude (movements east and west) and altitude (height above sea level) also play a role.

We can see that there is a relationship between latitude and altitude. The early American ecologist Hopkins developed a rough and ready rule that, for every degree of latitude and every 100–130 m in altitude, spring events are delayed by about 3–4 days.

As temperatures increase, sub-Arctic and upland habitats (on which grouse, for example, are dependent) will move further north and up the hills. If temperatures continue to increase, then these habitats will literally disappear off the top of the mountains.

Even if temperature stabilises, these populations are still vulnerable. I want to illustrate why this is the case by introducing some new terms: fragmentation, resistance and resilience.

3.3 Fragmentation, resistance and resilience

We can use resistance and resilience in relation to individual species and to ecosystems. The term fragmentation applies to species and habitat.

Resistance is the ability to maintain a population or an ecosystem despite changes in conditions. Resilience is the ability to ‘bounce back’ from changes in population (for a species) or conditions (ecosystem). Fragmentation happens as populations of species or ecosystems become more isolated from each other (or fragmented). Fragmentation means that species or ecosystems are more vulnerable to changes in environmental conditions.

Fragmentation is important when we consider resistance and resilience. This is because as a species or population and its range become fragmented, so this changes the population's ability to resist and bounce back from change. This also holds for the habitats and ecosystems.

Let's look back at our grouse, which is already finding it hard to make a living at the edge of its niche. We can see that rapidly changing climates can lead to localised extinctions.

While the disappearance of sub-Arctic habitats and species from the UK is troubling, habitat and populations will persist in other areas. See the example of the black grouse in Finland.

These are localised extinctions, they are serious, but a far greater concern is the extinction of species that are endemic (only found in) the UK. The Scottish crossbill is the only endemic bird species in the UK and is in danger of global extinction.

The Scottish crossbill has a very restricted range and specific habitat requirements. It is largely dependent on Scots pine forest, though is occasionally found in conifer plantations, and is only found in the Scottish Highlands. Its dependence on Scots pine forest is associated with high altitudes and high latitudes. This means that the forests are likely to move northwards and upwards as temperatures increase. If the habitat within Scotland decreases or becomes more fragmented, then the Scottish crossbill is at risk of extinction.

Web resources regarding this topic:

• Details of the UK Biodiversity Action Plan for this species

• BirdLife species factsheet

• Map of Scots pine distribution

• General overview of extinction risk

4 How apparently non-mobile organisms adapt to environmental change

4.1 Introduction

In the unit so far we have looked at relatively mobile species; that is, species where individual organisms can move about and, therefore, have the potential to react to changing environments by shifting location. We also saw that even for apparently mobile species like birds this is not always straightforward.

In this section we are going to consider the effects of changing environmental conditions on non-mobile species. We use the term non-mobile species where individual organisms stay in the same place. The use of the term organism reminds us that we are talking at the level of an individual; we are not talking about the species as a whole or an ecosystem.

Even apparently non-mobile species can migrate. They do so by dispersing seed, or spores in the case of fungi. Indeed, fungal spores can travel thousands of kilometres, and many of those who study food plants are gravely concerned about the effects that the arrival of new plant pathogens will have on UK food security.

Non-mobile species react much more slowly to environmental change. If changes in the environment are gradual then the range of a non-mobile species gradually expands or contracts to account for those changes. Seeds are dispersed and if they fall on favourable conditions they grow. If environmental changes are only short term or are very gradual, then the long time scales (especially in relation to woodland) involved in the dispersal of that non-mobile are of little consequence.

The problem occurs when environment changes happen relatively quickly and are part of a sustained pattern of environmental change. Non-mobile species like plants, especially those with long life cycles (slow growing and slow to mature trees), cannot adapt to rapid and sustained changes in environmental conditions. This issue is likely to be exaggerated in species that only disperse seeds over relatively short distances or where the habitat is fragmented.

4.2 Changing distribution of tree species within the UK

Models have been made to understand the impact on ecosystems in relation to projected changes that indicate a significant loss of these specific ecosystems.

• tundra by 55%

• tundra/taiga by 85%

• boreal conifers by 46%

• temperate evergreen by 52%.

Looking at the potential changes to UK forest cover, a study by the UK Forestry Commission reports that by 2080:

• Sitka spruce will become more suitable across the cooler uplands of Scotland and northern England, and also the eastern side of Scotland; the Suitable area in parts of lowland England may become Unsuitable; the southwest peninsula and Wales should, at least, remain Suitable.

• Corsican pine will become Very Suitable in eastern Scotland where it is currently Suitable, while growth rates will increase across southern England.

• Douglas fir will remain, at least, Suitable across most of south and east England, and Very Suitable in the West Midlands and much of the southwest and east Wales; the climate is predicted to become more suitable for Douglas fir across the whole of Scotland, but particularly in the east.

• Beech is likely to become Very Suitable across much of eastern Scotland, where it is currently marginally Suitable; in England, the areas where it is currently Suitable and Very Suitable are likely to contract northwards, and in areas of southern England, beech may no longer be Suitable.

So beech trees and beech ecosystems will be lost from southern England as they migrate north.

• A summary of the above report is also available from the Forestry Commission website.

• To learn a little more, the same author has produced a short pdf summary on beech and ash and responses to climate change.

5 Disappearing ecosystems: the example of the sub-Arctic willow

You have probably noted that the UK is like a bridge between species associated with mainland Europe and species you might associate with cooler northern climes.

Have a look at the map of world biomes.

The UK is classified as temperate forest. However, it is clear from our earlier discussions that northern and upland areas in the UK (in particular in Scotland) have a great deal in common with Scandinavian countries. Many of the species we share with northern European countries exist at fairly high altitudes in Scotland.

Sub-Arctic willow scrub is an assemblage of species found above the tree line at high altitudes. It contains a mix of Salix (willow) species, some normally associated with Arctic, sub-Arctic, or alpine areas and others with a northern distribution. In the UK its distribution is limited to a few high mountainous areas in the Scottish Highlands. In the UK it is a relic of the last glaciation; the habitat also exists in mountainous areas in Sweden and Finland.

The Scottish Crop Research Unit has published a report entitled ‘Population genetics of sub-Arctic willow’. What we learn from this report is that the willow species within this particular community can reproduce in two different ways: asexually (simply spreading) and sexually through the dispersal of viable seed. One of the issues for these communities is that the chances of sexual reproduction are limited because the plants are either male or female; many of the habitats contain very few genetically different plants, and some only one. This, coupled with the low level of pollen and seed dispersal, leads to populations with low genetic diversity.

This is a problem, because genetic diversity is important in relation to resistance and resilience. If a species within a particular ecosystem is genetically diverse, then the likelihood that there are individuals who are adapted to slightly different environmental conditions is higher.

These plant communities and the numerous invertebrates that depend on them are vulnerable to environmental change because their genetic diversity appears to be decreasing. They occupy habitats that are at the very southern edge of their range; those habitats are highly fragmented. These plant communities are essentially stuck on islands, with the lower and warmer areas between these isolated pockets acting as a barrier to dispersal and migration.

You can learn more about the research into these plant communities at:

• the Joint Nature Conservation Committee website, where you can find more information about the distribution and exact composition of this plant community

• the UK Biodiversity Action Plan website, which has information on wooly willow (Salix lanata)

• the ARKive website, which has more general information.

6 Responding to the challenges of species loss and extinction

It probably feels like there is very little that we as individuals can do directly to help conserve very rare and vulnerable habitats like sub-Arctic willow scrub. Indeed, we may have to accept that, given the predicted levels of anthropogenic climate change, it is very likely that we will lose many species associated with more northerly climates. Some, like the sub-Arctic willow scrub, will continue to exist in the Nordic countries. The future of species like the Scottish crossbill is less certain; further research is required.

What can we do? Together I think we can do a lot. For example:

• we can assist with research through volunteer networks like the UK Phenology Network and the OU's own iSpot biodiversity programme

• we can look at the ways that we manage our own green spaces – private green spaces are a mosaic of habitats that could possibly help species disperse

• you can join the British Trust for Conservation Volunteers and help to restore degraded habitats in your area

• you can take steps to reduce your carbon and ecological footprints.

Acknowledgements

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Text

Unit authored by Ronald Macintyre

Unit image

Getty photodisc

Links

All links accessed 27 November 2009.

Gregory, R.D., Willis, S.G., Jiguet, F., Voříšek, P., Klvaňová, A., et al. (2009) An Indicator of the Impact of Climatic Change on European Bird Populations PLoS ONE 4(3): e4678. doi:10.1371/journal.pone.0004678

Special Issue of Journal Climate Research dedicated to bird migration http://www.int-res.com/abstracts/cr/v35/n1-2/

Sparks, T.H., Dennis, R.L.H., Croûton, P.J., Cade, M. (2007) 'Increased migration of Lepidoptera linked to climate change', European Journal of Entomology, vol.104, pp.139-43, http://www.eje.cz/pdfarticles/1207/eje_104_1_139_Sparks.pdf

Huntley, B., Collingham, Y.C., Willis, S.G., Green, R.E. (2008) Potential Impacts of Climatic Change on European Breeding Birds, PLoS ONE 3(1): e1439. doi:10.1371/journal.pone.0001439, http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0001439, last accessed 21 May 2009

Broadmeadow, M. (2002) Climate Change - Impacts on UK Forests, Forestry Commission Bulletin 125, Forestry Commission Publications, UK

Green, R.E., Harley, M., Miles, L., Scharlemann, J. , Watkinson, A., Watts, O. (2003) Global Climate Change and Biodiversity, http://www.jncc.gov.uk/pdf/MJHGlobalclimatechange_14.08.03.pdf, last accessed 21 May 2009

Scottish Montane Willow Research Group (2005) Biodiversity: Taxonomy, Genetics, and Ecology of Sub-artic Willow Scrub, Edinburgh, Royal Botanic Gardens