Wordles are totally underrated. I think they should be used alongside abstracts. Time to wrap up soon, so here's a wordle of my blog.
Friday, 2 January 2015
Saturday, 27 December 2014
Pollution and phenology
The most alarming of all man's assaults upon the environment is the contamination of air, earth, rivers, and sea with dangerous and even lethal materials. This pollution is for the most part irrecoverable; the chain of evil it initiates not only in the world that must support life but in living tissues is for the most part irreversible. - Rachel CarsonThe above quote is taken from Carson's Silent Spring, published in 1963 but sadly still relevant today. Arguably, climate change has overtaken pollution as a concern for the environmentalism movement.
I was wondering about other environmental changes associated with urbanisation which led me to consider the effect of car exhaust fumes on phenology. Vehicular emissions are the major source of air pollution in urban environments (Brophy et al. 2007). These are mostly made up of nitric oxide (NO) and nitrogen dioxide (NO2).
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Car exhaust fumes. Source: the times |
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Hieracium pilosella. Source: wikipedia |
Traffic is also a major contributor to heavy metal contamination in soils in urban and roadside environments (Zereini et al., 2007). Ryser and Sauder (2006) found that heavy metal contamination of soils delayed flowering phenology in Hieracium pilosella. They found that flowering phenology was highly sensitive to metal contamination, being affected at very low levels.
Thursday, 11 December 2014
Urbanisation (again)
I found a study by Dominoni et al. (2013) which looked at the reproductive phenology of blackbirds (Turdus merula) (Fig. 1) and how this is affected by artificial light. They found that birds affected by night light developed their reproductive system and moulted earlier than those which were not exposed to light. I was interested in this because they used experimental conditions to determine the effect of artificial light, so we can be sure that it wasn't temperature having the effect.
I was thinking there are probably many unaccounted for factors in studies the effects of urbanisation on phenology. Wherever there is a city there will be increased temperatures, light pollution, sources of food, pollution... I'm struggling to find papers that actually separate these effects.
For instance I found this paper by Schoech and Bowman (2008) looking at the reproductive phenology of Florida Scrub-Jays (Aphelocoma coerulescens) (Fig. 2). Those birds from suburban habitats breed sooner in the year. I wrote about how this is makes animals more competitive in a previous post. The authors measured plasma levels of protein, etc. in birds and found it to be higher in the suburban birds vs the rural birds. They inferred from this that earlier breeding is caused by the availability of protein. I think it's good evidence for differences in diet between the two populations. And, they've collected data showing that breeding phenology varies between the two populations. Their results are consistent with their hypothesis that food availability would cause earlier breeding. But, I don't think that necessarily proves the connection because any field study like this will be too confounded.
In fact, the authors found that leutanizing hormone was also elevated in birds. Leutanising hormone is part of the reproductive physiology of birds, the cycle of which is connected to day length (Sharp et al. 1998). Maybe light pollution could have something to do with it, too?
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Fig. 1. Male blackbird. Source: http://shropshirebirder.co.uk/blackbird.html |
I was thinking there are probably many unaccounted for factors in studies the effects of urbanisation on phenology. Wherever there is a city there will be increased temperatures, light pollution, sources of food, pollution... I'm struggling to find papers that actually separate these effects.
For instance I found this paper by Schoech and Bowman (2008) looking at the reproductive phenology of Florida Scrub-Jays (Aphelocoma coerulescens) (Fig. 2). Those birds from suburban habitats breed sooner in the year. I wrote about how this is makes animals more competitive in a previous post. The authors measured plasma levels of protein, etc. in birds and found it to be higher in the suburban birds vs the rural birds. They inferred from this that earlier breeding is caused by the availability of protein. I think it's good evidence for differences in diet between the two populations. And, they've collected data showing that breeding phenology varies between the two populations. Their results are consistent with their hypothesis that food availability would cause earlier breeding. But, I don't think that necessarily proves the connection because any field study like this will be too confounded.
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Fig. 2. Florida Scrub-Jay. Such a beautiful bird! Source: http://barbrichphotography.blogspot.co.uk/2011/05/backyard-birding.html |
Wednesday, 10 December 2014
Urbanisation - light pollution vs urban heat island
Light pollution and the urban heat island are both associated with urbanisation. Since blogging about these I've been wondering how studies can be sure they're really seeing the effect of one or the other on phenology.
During winter birds need to get up early to start feeding, as they use their energy up overnight, and need to eat or they'll die of starvation. Ockendon et al. (2009) separated the urban heat island from effects of light pollution by hypothesis testing. In urban areas, they could get up later if it's warmer because they won't have used as much energy up over night staying warm, or they could get up earlier and start feeding sooner because there are artificial sources of light. They found birds appearing at garden feeders later in the a.m. in urban areas in Britain than in rural ones - pointing towards the urban heat island. They also found a statistically significant difference between the response of species, something you might expect if you've been following this blog. They thought the Eurasian collared dove might be getting up to feed earlier because of competition from feral pigeons (Fig. 1).
They used modelling to show that urbanisation, defined as the percentage of the surrounding 1 km square classified as urban/suburban, is
statistically significant as a predictor variable for time of first bird
arrival. However, they did not separate the effects of light pollution and temperature...
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During winter birds need to get up early to start feeding, as they use their energy up overnight, and need to eat or they'll die of starvation. Ockendon et al. (2009) separated the urban heat island from effects of light pollution by hypothesis testing. In urban areas, they could get up later if it's warmer because they won't have used as much energy up over night staying warm, or they could get up earlier and start feeding sooner because there are artificial sources of light. They found birds appearing at garden feeders later in the a.m. in urban areas in Britain than in rural ones - pointing towards the urban heat island. They also found a statistically significant difference between the response of species, something you might expect if you've been following this blog. They thought the Eurasian collared dove might be getting up to feed earlier because of competition from feral pigeons (Fig. 1).
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Fig. 1. |
Monday, 8 December 2014
Phenology and light pollution (part 2)
Part 2!
Plants
Currently there are no studies on plant phenology and light pollution (Neil and Wu,2006). Although I found this dodgy paper on light pollution impact on tree autumn phenology that reads like it was written by a child and hasn't got proper references
Moths
van Geffen et al. (2014) found that artificial light causes the male Mamestra brassicae (Fig. 1) caterpillar to pupate earlier, The females don't experience this. Differences in pupation duration are strong - by the time the adult moths from the control sample (dark) emerged, after 110 days, ~85% the light polluted moths had already emerged.
I think there is generally not as much research on light pollution and phenology as compared with temperature and phenology.
Plants
Currently there are no studies on plant phenology and light pollution (Neil and Wu,2006). Although I found this dodgy paper on light pollution impact on tree autumn phenology that reads like it was written by a child and hasn't got proper references
Moths
van Geffen et al. (2014) found that artificial light causes the male Mamestra brassicae (Fig. 1) caterpillar to pupate earlier, The females don't experience this. Differences in pupation duration are strong - by the time the adult moths from the control sample (dark) emerged, after 110 days, ~85% the light polluted moths had already emerged.
Fig. 1 Mamesra brassicae moth |
I think there is generally not as much research on light pollution and phenology as compared with temperature and phenology.
Wednesday, 3 December 2014
Phenology and light pollution (part 1)
We've heard about the Urban Heat Island effect before where plant phenology is affected by increased temperatures around urban areas. But, different species' phenologies are affected by many factors other than temperature. In this post and the next one I'll look at how light pollution can affect phenologies (Fig. 1).
Birds
Light pollution can affect bird migration, but can't really affect the timing (phenology). Interestingly, some migratory birds are guided by stars in the night sky, and light pollution confuses them on their way and they can collide into each other and die (Longcore and Rich, 2004; Poot et al., 2008)!
Zooplankton
Aquatic invertebrates move up and down the water column in response to changing light conditions over 24 hours, something called "diel vertical migration" (Gliwicz 1986; cited in Longcore and Rich, 2004). Daphnia is an aquatic invertebrate (Fig. 2). Moore et al. (2000 cited in Longcore and Rich, 2004) found that the range of its diel vertical migration is affected by artifical light sources.
More next time...
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Fig. 1 From Light Cities: Sea Level by David Stephenson (2012) |
Light pollution can affect bird migration, but can't really affect the timing (phenology). Interestingly, some migratory birds are guided by stars in the night sky, and light pollution confuses them on their way and they can collide into each other and die (Longcore and Rich, 2004; Poot et al., 2008)!
Zooplankton
Aquatic invertebrates move up and down the water column in response to changing light conditions over 24 hours, something called "diel vertical migration" (Gliwicz 1986; cited in Longcore and Rich, 2004). Daphnia is an aquatic invertebrate (Fig. 2). Moore et al. (2000 cited in Longcore and Rich, 2004) found that the range of its diel vertical migration is affected by artifical light sources.
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from http://www.micromagus.net/microscopes/pondlife_cladocera.html |
More next time...
Friday, 28 November 2014
Phenological changes and mankind
This post will look at some of the impacts phenological changes can have on mankind, and whether these are good or bad.
"Ecosystem services" are the benefits people gain from ecosystems. They can be split up into into provisioning, regulating, cultural and supporting services (Fig. 1).
Provisioning services
Pelagic plankton and fish in the North Sea show phenological changes in response to warming sea surface temperatures, but their responses are mismatched in time (Edwards and Richardson, 2004). We've heard about decoupling between trophic levels before. In this context, these phenological mismatches could detrimentally effect fisheries, because the success of fish depends on their synchronisation with growth of plankton (because they eat them).
Regulating services
We've heard before that the growing season is lengthening. A longer growing season in northern Europe (Fig. 2) could be beneficial for agricultural yields and insect populations, and allow us to introduce crops to new areas where they previously could not grow (LaValle et al., 2009).
However, again, there is concern that there could be mismatches in the phenology of flower production and pollinator flight activity. Memmott et al. (2007) used phenological data from 1884 - 1916 on the first and last dates of flowering, and visits from pollinators, to predict what would happen to plant-pollinator interactions in a simulation of future global warming for the years 2070-2100. They found that most pollinators would be at risk in this scenario, and that local extinction of pollinators will put plant sexual reproduction at risk, and cause plant populations to decline.
Cultural services
Ecotourism has explicit links with plant phenology:
Sparks et al. (2012) looked at the spring snowflake (Leucojum vernum) (Fig. 3) which the flowering of is a tourist attraction in Poland. They found that earlier flowering was associated with a long flower duration. This would be beneficial for ecotourism.
This is all well and good. But ecosystem services frame the biosphere as valuable only because it provides mankind with something, rather than respecting life for its intrinsic value.
"Ecosystem services" are the benefits people gain from ecosystems. They can be split up into into provisioning, regulating, cultural and supporting services (Fig. 1).
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Fig. 1 Examples of ecosystem services by type. Taken from unep.org. |
Provisioning services
Pelagic plankton and fish in the North Sea show phenological changes in response to warming sea surface temperatures, but their responses are mismatched in time (Edwards and Richardson, 2004). We've heard about decoupling between trophic levels before. In this context, these phenological mismatches could detrimentally effect fisheries, because the success of fish depends on their synchronisation with growth of plankton (because they eat them).
Regulating services
We've heard before that the growing season is lengthening. A longer growing season in northern Europe (Fig. 2) could be beneficial for agricultural yields and insect populations, and allow us to introduce crops to new areas where they previously could not grow (LaValle et al., 2009).
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Fig. 2. Rate of change of crop growing season 1975-2007. Taken from LaValle et al. (2009). |
However, again, there is concern that there could be mismatches in the phenology of flower production and pollinator flight activity. Memmott et al. (2007) used phenological data from 1884 - 1916 on the first and last dates of flowering, and visits from pollinators, to predict what would happen to plant-pollinator interactions in a simulation of future global warming for the years 2070-2100. They found that most pollinators would be at risk in this scenario, and that local extinction of pollinators will put plant sexual reproduction at risk, and cause plant populations to decline.
Cultural services
Ecotourism has explicit links with plant phenology:
"...autumn tourists, including “leaf peepers”, are estimated to spend US$375 m in Vermont alone ... In Japan, both autumn colour watching (“momijigari”) and viewing of spring flowers (“hanami”) are hugely important; 10 million visitors a year visit the famous 59-ha Arashiyama National Forest near Kyoto ... and when cherry flowering coincides with public holidays this attracts an additional 1.4 million tourists to Hirosaki... Cherry flowering is also a huge attraction in Korea, China and across North America where an estimated 700,000 visitors visit Washington D.C. for the cherry blossom festival..." - Sparks et al. (2012; p. 1)
Sparks et al. (2012) looked at the spring snowflake (Leucojum vernum) (Fig. 3) which the flowering of is a tourist attraction in Poland. They found that earlier flowering was associated with a long flower duration. This would be beneficial for ecotourism.
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Fig. 3. Spring snowflake blossom heralds the start of spring. Source: http://www.panoramio.com/photo/68598215 |
This is all well and good. But ecosystem services frame the biosphere as valuable only because it provides mankind with something, rather than respecting life for its intrinsic value.
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