I am looking for a brief peer review on this research paper I have drafted for ENG 102. My instructor has asked me to identify three areas I feel I could improve:
1) Clarity of message/focus, 2) explaining complicated material in an approachable way, 3) Summary of ideas/conclusion
Antarctic Vascular Plants and their Relationship with Climate Change
The southernmost continent of Antarctica ranks among the Earth's most inhospitable
environments. Known to all as a bitter, icy wasteland, it may come as a surprise for some to learn
that Antarctica is home to a diverse collection of exceedingly resilient life-forms. From the
microscopic archaeans buried beneath the ice in the deep south to the myriad of sea creatures
who call the frigid waters along the Antarctic coast their home, perhaps the most unexpected
population is that of Antarctica's flourishing community of mosses, lichens, and even two native
species of flowering plants. Each of these have developed complex systems of survival to protect
themselves against their harsh environment. Climate change, however, threatens to rapidly alter
the Antarctic ecosystem and the plants and animals that comprise it. While warmer temperatures
and wetting growing regions have led to incredible growth for Antarctica's two species of native
flowering plants in particular, long-term warming may threaten the adaptations that make these
plants so unique.
The purpose of this research paper is to discuss and summarize the relationship between
Antarctica's native species of flowering plants. Research conducted and reported by experts in
the field of Antarctic biology and ecology serve as the backbone of this evaluation. Scientists
from around the world have dedicated years to these studies and the study of the Antarctic
continent at large. Their collective efforts, summarized here, are sure to be essential to unlocking
the secrets behind how these plants survive in such a dry, cold environment, and how those
adaptations may produce insight into how to protect Antarctica's vascular plants, as well as how
to better protect other species from the threat of freezing.
Plant life accounts for the vast majority of Antarctica's native species. Most of these
plants grow in the coastal regions and subantarctic islands, where proximity to animal activity
and warmer temperatures (relative to the ice sheets) create a more hospitable growing zone.
According to the British Antarctic Survey, "there are around 100 species of mosses, 25 species of
liverworts, 300 to 400 species of lichens, and 20-odd species of macro fungi," all growing on the
island and coastal regions that amount to roughly 1% of the total Antarctic landmass. Out of all
of these, the majority resides in the western Antarctic peninsula. While some of the more
resilient species can be found deeper into the southern regions, these are rare.
Out of the five hundred or so plant species known to grow in Antarctica, only two are
flowering (or "vascular," by which they will be referred going forward). Vascular plants are
plants that possess "complex vascular structures that transport nutrients throughout their leaves,
stems, and roots," (Bishop). As such, these species are not usually well-adapted to such a cold
environment, as these vascular structures and their complex root systems rely heavily on water
for their transport mechanisms. Against all odds, however, two species have developed
complicated methods by which they survive and gain their nutrients, methods which researchers
are racing to decode.
The first of these species is known as Antarctic hair grass, scientific name Deschampsia
antarctica (D. antarctica), which grows in tall tufts. According to Caitlyn Bishop's article "The
Plants of Antarctica," this grass can be found most commonly comprising coastal meadows. D.
antarctica benefits from growing in the landing grounds for visiting penguin colonies and
elephant seals whose waste contributes essential nutrients to the soil. The other of Antarctica's
two vascular plants is the Antarctic pearlwort, scientific name Colobanthus quitensis (C.
quitensis). Found mostly in rockier regions, C. quitensis grows much smaller than D. antarctica,
reaching a meager average of approximately five centimeters at full growth (Bishop).
Research reported by Phoebe Weston for her article, "Flourishing plants show warming
Antarctica undergoing 'major change'," compares the spread of both Antarctic hair grass and
pearlwort between 1960 to 2009 and 2009 to 2018. This research found that the hair grass spread
five times faster from 2009 to 2018 than it did between 1960 and 2009. Similarly, the pearlwort
saw twice that rate of spread. There are many possible explanations for such increases. The
research Weston cites proposes a measurable increase in average summer temperatures and
changes in seal presence. Other research, however, suggests that there may be more specific
causes for the plants' spread that affect each species independently.
All plants rely on a variety of mineral nutrients. Among these essential minerals is
nitrogen. According to the British Antarctic survey, "in coastal Antarctica, much of the nitrogen
is locked in organic matter in the soil, which has been slow to decompose in cold conditions." As
the climate warms, however, Antarctica's vascular plants may have greater access to previously
unprecedented quantities of organic nitrogen. Research conducted by Claudia Rabert et al. in
2017 evaluates the impact that an increase in nitrogen availability has on Antarctic hair grass and
pearlwort. Their research found evidence that D. antarctica recovered this newly available
nitrogen more efficiently than C. quitensis. Speculation from the British Antarctic Survey also
suggests that decreased fur seal activity provides a less hostile environment for the hair grass to
spread, as the seals are prone to trample and kill off patches of the hair grass. Regarding C.
quitensis, however, research is ongoing. A small increase in nitrogen intake efficiency does little
to explain its population growth, as does the presence or lack of seals outside of their growing
zones.
In order to weather the elements and gain the nutrients they need to survive in one of the
world's most inhospitable landscapes, Antarctic hair grass and pearlwort have had to adapt over
the years. When compared to other vascular plants, these two species possess a remarkable level
of resistance to freezing temperatures. According to Costanza F. Ramirez et al., "different studies
have reported high carbohydrate concentrations in the leaves of both Antarctic vascular species,
mainly soluble sugars." These carbohydrates play a key role in the plants' freezing resistance as
they offer an alternative method by which D. antarctica and C. quitensis can generate energy
when usual methods of respiration like photosynthesis are not as effective. This trait, developed
by way of natural selections over generations, may be at risk. As the Antarctic warms, these
plants' need for such an adaptation diminishes. Already, a study conducted and reported by
Angela Sierra-Almeida et al. has "demonstrated that although both plant species exhibited a great
ability to cope with freezing temperatures during the growing season, their vulnerability to suffer
freezing damage under a warming scenario increase." That is to say, as the plants grow under
increasingly warm conditions, they begin to rely more heavily on more traditional forms of
respiration than previous specimens. When winter's extreme colds and biting winds return, these
plants are becoming less and less likely to survive in great numbers.
Another adaptation prevalent among the Antarctic vascular plants can be observed in the
methods by which the pollinate and reproduce. Since pollinators like bees and birds lack any
significant presence in these plants' growing zones, they have had to rely on alternative methods
in order to spread. Antarctic hair grass, with its long, flowing leaves, takes advantage of its
windy environment to spread its pollen. It can also, in some cases, self-fertilize depending on the
anatomy of a given specimen. Antarctic pearlwort, on the other hand, cannot rely on the wind to
carry its pollen due to its small size. Instead, the Antarctic pearlwort relies entirely on
self-fertilization.
No plant exists in a vacuum. All organisms participate in complicated, sometimes
invisible ecosystems in which multitudes of different species collaborate and coexist in ways that
affect their environment and each other. D. antarctica and C. quitensis are no exceptions. In
order to better understand these plants and their remarkable adaptations, scientists have turned to
the evaluation of their relationship with the ecosystem at large. As the dominant plants in their
respective growing zones due to their vast populations, Antarctic hair grass and pearlwort must
certainly play a pivotal role in the ecology of said growing zones. Data collected and analyzed by
researchers Beenish Naz et al. suggested that these "dominant plants significantly influence
bacterial activity in the soil and plant-associated soil favor more antagonistic bacterial
communities than bulk soil," (8).
Along a similar vein, Jorge Gallardo-Cerda et al. isolated several strains of rhizobacteria
that, when present in the rhizospheres of Antarctic hair grass or pearlwort, significantly increase
the plants' resistance to salinity (an importance resistance thanks to their mostly coastal growing
zones). This evidence suggests a positive relationship between the Antarctic vascular plants and
at least some strains of bacteria found in the soil, as the vascular plants contribute to an active
environment for the bacteria, while the bacteria contribute to the vascular plants' resistance to
one of the harsh influences of their environment. In this case, evaluating the plants' relationships
to their microbial environment helped isolate an important adaptation through which they have
been able to survive the salt-heavy air, soil, and water present in their growing zones.
Research on all of the material referenced in this paper is ongoing, and not all researchers
agree on the findings and their respective significances. An example of this can be observed in
the interaction between Marco A. Molina-Montenegro et al. and Casanova-Katny et al. In a
paper published in the Journal of Vegetation Science, Molina-Montenegro et al. presented the
conclusion that a species of Antarctic macrolichen "[acted] as a 'nurse species' for co-existing
lichens and mosses, and might facilitate the vascular plant Deschampsia antarctica,"
(Molina-Montenegro 606). Soon after, Casanova-Katny et al. published a rebuttal of these
findings, prompting Molina-Montenegro et al. to publish a response reaffirming their original
findings. The consequential proposal of this interaction, which suggests a strong relationship
between Antarctic hair grass and the species of Antarctic macrolichen referenced by both
research groups, goes to demonstrate a deeper connection between Antarctica's vascular species
and the wider ecosystem in which they live.
A warmer climate presents multiple threats to Antarctica's vascular plants. Natural
selection abandoning the cold-resistance mechanisms necessary for their survival is one such
threat. Another, less subtle danger comes in the form of competition. In recent years, a warmer,
wetter climate has served as an open invitation for the arrival of a third, non-native vascular
plant. Annual bluegrass, scientific name Poa annua (P. annua) is an invasive species found all
over the world. Commonly used in golf courses, this species is known for its aggressive behavior
with other grasses, making it a substantial threat to Antarctica's native vascular plants, should
trends continue on as they have in the areas of temperature and water-availability.
Another paper published by Marco A. Molina-Montenegro et al. entitled, "Increasing
impacts by Antarctica's most widespread plant species as a result of direct competition with
native vascular plants," evaluates the impact that P. annua has had thus far on D. antarctica and
C. quitensis. In their research, Molina-Montenegro et al. determined that the survival rates of
both native vascular plants decreased in the presence of the invasive species compared to when
they grow together without P. annua (27). Taking it further, the researchers looked ahead to a
more water-rich scenario to try to determine the invasive grass's possible long-term impacts on
populations of the native plants.
They found that low-density populations of C. quitensis growing alongside higher
densities of D. antarctica and P. annua suffered more greatly than when grown only with D.
antarctica. With a higher population of C. quitensis, however, the observed mortality rate was
even more significant. D. antarctica, however, suffered far less than C. quitensis under the same
conditions. However, the researchers go on to conclude that "C. quitensis communities will
become more resistant to invasion, while those dominated by D. antarctica will become less
resistant," (Molina-Montenegro et al. 1), which holds consistent with the behavior of P. annua in
other grassy environments. Further analysis with P. annua as the minority species indicated that
P. annua suffered only slightly, favoring C. quitensis over D. antarctica. One of the most
concerning findings of this research is the fact that when grown in the presence of the Antarctic
vascular plants, the invasive species saw much greater population growth than when grown
independently.
As climate change continues to change the landscape of Antarctica and the world at large,
researchers race against the clock to uncover as many clues as possible as to the adaptations and
mechanisms that have combined to produce such a unique class of vascular plant. As
documented and discussed in this research paper, many discoveries have led to a more robust
understanding of these plants and their place in the wider Antarctic ecosystem. The release of
previously unobtainable sources of nitrogen due to warming temperatures, the relationships
between the Antarctic vascular plants and the bacteria with which they share their soil, the
discussion on the importance of Antarctic macrolichen on the propagation of the vascular
species, and the threat of an aggressive invasive species are all important pieces of the larger
puzzle. To truly ascertain the full scope of how these plants have evolved and how that
knowledge may go on to contribute to other studies, far more research and study is required.
The potential applications for a mechanism that provides freeze-resistance to vascular
plants could be immensely beneficial. Such a knowledge could lead to more efficient agriculture,
as well as preventing crops from Spring freezes. It could go so far as to unlock the potential for
winter growing seasons, or even the opportunity to cultivate crops in areas previously considered
too hostile for agriculture. With enough resources and time, there's no telling what scientists
could still learn from these fascinating, at-risk species. Time, however, may be running out as
natural selection is bound to abandon these distinctive traits for the sake of efficiency as the
climate gets progressively warmer.
Works Cited
