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It’s Happening: The Cost of Convenience
Phenology
Phenology is the study of the timing of natural events in the biological world (“What is
Phenology”). These events include everything from what time flowers bloom during the year to the timing
of whale migrations. Organisms often align themselves with phenological events in order to interact with
one another through predation or symbiosis. Ecosystems are heavily reliant on events working time in
order to function smoothly.
There are three major abiotic factors that affect phenology.
The first is precipitation, or the amount of rain that an area
receives. Plants rely on water to further their life cycles, while
some insects use pools of water to breed and lay eggs.
Precipitation rates often vary throughout the year, signaling
changes in organisms which are rainfall-dependent.
The second abiotic factor is the amount of sunlight an area
receives. In the northern hemisphere, spring and summer occur
when the Earth is farthest from the sun but receives more
Figure 1: An example of precipitation.
radiation due to the tilt of the Earth’s axis. During this time,
days are longer and nights shorter. Fall and winter occur when
the Earth is closest to the sun, but receives less radiation because the Earth is tilting away from the sun.
Nights grow longer during this period and the days shorter. This is reversed in the southern hemisphere.
Plants and other organisms that photosynthesize need sunlight to complete their metabolic cycles. When
days grow shorter and the amount of light increases, plants will revert to anaerobic respiration and often
go into a dormant stage. For example, trees will lose their leaves during fall and winter. When the amount
of light increases, the plants will grow leaves to capture the light for photosynthesis again.
The final abiotic factor that affects phenology is the temperature of an area. Organisms often have
temperature-specific gene and behavioral responses which are triggered by an increase or decrease in
temperature. For example, dogwood trees begin to bloom once the area reaches a certain temperature
which corresponds with spring in most areas, and many animals begin to lose winter molts after
temperatures increase and snow would no longer be present. Temperature also dictates the length of time
an organism may survive in a certain area. Mosquitoes and many other insects begin to breed as the
temperatures grow warmer and them die off or hibernate as cooler temperatures approach, creating a
natural cycle of life and death.
Check This Video: http://www.youtube.com/watch?v=RNs3XpRmRfI for more on how
phenology is defined and how it works.
Of the three factors, temperature and precipitation are the two which are most affected by climate
change. Human actions which cause an increase in greenhouse gases not only result in a warmer overall
temperature, but more specifically affects the established climate in certain areas with dramatically different
results. Locations that have historically been arid could become more inhospitable, perhaps becoming
colder and receiving less rainfall. Areas that are warm and wet could become warmer and receive more
violent storms. This change in precipitation and temperature could affect the phenological cycles of some
organisms and not others, throwing off the delicate timing that the organisms have established over
thousands of years. Additionally, humans change the environment through urbanization and deforestation.
In urban areas, temperatures can deviate from unaltered landscape due to changes in albedo and result in
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It’s Happening: The Cost of Convenience
some species receiving warmer or cooler temperatures than on average. Once again, phenological cycles
that depend on temperature would be altered by this urbanization effort.
Climate change’s impact on phenology is indirect. Overall, the changing climate affects the three
factors that affect phenology directly. Climate is the composite or generally prevailing weather conditions
of a region, such as temperature, air pressure, humidity, precipitation, sunshine, cloudiness, and winds,
throughout the year, averaged over a series of years. As these factors are changing the phenology in
different environments changes as well. For example, take a flower that blossoms when the temperature is
between 50 and 65 degrees Fahrenheit. If the temperature in a specific town begins to grow warmer earlier
over a few years, the blooming date of the species
will move forward in response. This could be
potentially harmful for animals or insects that are
dependent on this species.
Case Study: Edith’s checkerspot butterfly
(Adapted from Hannah 9)
The Edith’s checkerspot butterfly of the
Nymphalidae family lives in the northwestern United
States, particularly along the Sierra Mountains. These
butterflies fed primarily upon the nectar of the blueeyed Mary, whose blossoms while the larvae pupated
and the adults emerged, around March to June
(“Butterflies and Moths”). However, warmer
temperatures have caused the blue-eyed Mary to
bloom earlier than the adults emerged. The checkerspot has recently begun to feed upon the English
plantain more frequently as a result, or have moved to higher elevations where the blooming of the Mary
matched the butterfly’s normal flight time. The blue-eyed Mary now lacks a primary pollinator, which the
English plantain has gained, and is now less capable of
Figure 2: The English Plaintain
reproducing.
Figure 3: The Edith’s Checkerspot Butterfly
Figure 4: The Blue Eyed Mary
As climate change alters the timing of phenological events, organisms that rely on one another can
no longer depend on their relationships to occurs at the same time. As with the case of the Edith’s
checkerspot and the blue-eyed Mary, organisms that have a symbiotic relationship might find one partner
arriving too early or too late, which could result in starvation or other undesirable effects among one or
both of the partners. Conversely, other less-desirable organisms might benefit from the change in
phenological events which could cause considerable damage. As the weather grows warmer and wetter in
some parts of the world, insects are breeding and developing at a more aggressive rate, and staying around
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It’s Happening: The Cost of Convenience
for longer than before. When this occurs with disease vectors, such as the mosquito, the rate of deadly
infections could increase exponentially (USA NPN).
Lab:
A potential lab that could be performed to show the effects of a changing climate is to change
the different amounts of sunlight and water that plants are receiving. This will effectively
demonstrate the responses plants can have to a climate that is constantly changing. To perform this
lab you will need: 4 cosmos flowers, 2 heat lamps and access to water.
1. Place the first flower under a heat lamp. For this flower you will maintain the same amount
of heat, representing an increase in temperature. You must also provide the cosmo with 300
mL of water each day to represent normal water amounts.
2. Place the second flower in sunlight and give the flower 300 mL of water a day. This is your
control plant.
3. Place the third flower under a heat lamp. This plant will recieve 600 mL of water daily. The
increase in water as well as the extra heat represents a climate where an increase in heat and
water has happened.
4. Place the fourth flower into sunlight and give the plant 600 mL of water a day. This plant
represents an environment where no change has taken place in the temperature, but the
amount of water has increased dramatically.
5. Observe the plants daily. Record any observations about the plants including, which plant
blooms first, which plant blooms last, and which factor has the greatest impact on the change
in timing patterns for the plant.
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It’s Happening: The Cost of Convenience
Figure 5: Four examples of cosmos
To further study the effect of climate change on phenology satellite data is a very useful tool. Satellites
have an ability that humans themselves do not have, to scope out changes in phenology in large areas over
large amounts of time. This allows satellites to map the overall effect of climate change on phenology with
ease. As an example below is included photos taken from space of the Southeast United States.
Figure 6: The above data is from 2001.
Figure 7: This above data is from 2012.
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It’s Happening: The Cost of Convenience
In these satellite images the maximum NDVI is represented. NDVI stands for the normalized
difference vegetation index, which is a graphical indication to analyze whether an area contains live
green vegetation. When viewing these images make sure to ask yourself things like how have the max
NDVI months changed for the Southeastern USA between 2001 and 2012. What are some factors that
could account for this change? What consequences could this change create? Keep in mind that climate
change can have both negative and positive effects in different areas.
In addition to ecological damage, changes in phenological events could also cause financial
damage. Insects that develop more quickly and remain for longer periods of time could cause more
damage to crops and affect the size of harvests. This could be even more devastating if helpful creatures,
such as pollinators and natural pest control species, are not available to tend to the crops because of the
changing climate. Additionally, several festivals around the world depend on phenological events. The
cherry blossoms in Washington D.C. bring many tourists in from around the world, who are now often
disappointed to find that the time for the blossoming already passed (USA NPN).
Mathematical Model: http://www.regional.org.au/au/asa/2010/climatechange/futurefarming/7018_griffithsw.htm
This model is a representation of the overall changes of climate change on phenology in grain yield.
The model takes into account the predicted change in climate in Australia and its potential effects on CO2
levels, temperature and rainfall amounts and frequency. The biophysical processes in the model are driven
by the climatic inputs of daily rainfall, minimum and maximum temperature, solar radiation, humidity and
wind run.
Glossary
Phenology-the study of the timing of natural events in the biological world
Abiotic-non-living and not from living organism
Climate-composite or generally prevailing weather conditions of a region, such as temperature, air
pressure, humidity, precipitation, sunshine, cloudiness, and winds, throughout the year, averaged over a
series of years
Symbiosis-a relationship between two different organisms that benefits at least one of the organisms
Vector- an organism that carries a disease
Normalized Difference Vegetation Index-a graphical indication to analyze whether an area contains live
green vegetation
Works Cited
"Butterflies and Moths of North America | Collecting and Sharing Data about Lepidoptera." Butterflies
and Moths of North America | Collecting and Sharing Data about Lepidoptera. Web.
Hannah, Lee Jay. Climate Change Biology. Burlington, MA: Academic, 2011. Print.
"What Is Phenology? - National Wildlife Federation." What Is Phenology? - National Wildlife Federation.
Web.
"USA NPN National Phenology Network." Why Phenology? Web. 19 May 2014.
cosmos-montage-flowers.jpg
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It’s Happening: The Cost of Convenience
http://www.questionsonislam.com/article/miracle-rain
http://phenology.cr.usgs.gov/get_data_250e.php
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