mpetracchi's blog

To understand just how devastating an increase in greenhouse gases could be for our planet we must first understand how greenhouse gases work. Energy reaches our planet in the form of solar radiation and is either reflected or absorbed and released as infrared radiation. Normally this radiation would leave the planet, however, gases in the atmosphere act as a one way mirror allowing solar radiation in but trapping IR radiation. Without any gas we could not survive, however, too much will cause problems. Our atmosphere is made of 78% N2, 21% O2, 1% Ar, 0.4% H2O and <0.1% of other gases with carbon dioxide at 0.041%. Carbon dioxide levels are 'low' compared to the rest of the gases in the air, so why do speakers use it as a key point of climate change conversation?  Airborne concentrations of this gas have been steadily increasing since data was first recorded in 1960. A longitudinal study by the NOAA Earth System Research Laboratory has shown that from 1960 to today carbon dioxide levels have risen by 90 ppm (parts per million). This seemingly small increase could have devastating affects on our enviornment. Global temperatures have been rising from the increase in efficient green house gases such as carbon dioxide, and also notably, methane, and nitrous oxide. A 2018 study of temperature increases and it's affect on organsim ranges predict that at a 3.2 C change in average temperature could result in the geographic range loss greater than 50% for 49% of insects, 44% of plants, and 26% of vertabrates. These results are worrying. The future of our species and others lies in question. We must make a change now in order to avoid catastrophe.

To understand just how devastating an increase in greenhouse gases could be for our planet we must first understand how greenhouse gases work. Energy reaches our planet from the sun in the form of solar radiation. When it touchs the surface it is either reflected away or is absorbed and released as infrared radiation. This radiation would normally leave the atmosphere however gases in the atmosphere act as a one way mirror and trap some of it. Without any gases we could not survive, however with too much we will also run into problems. Our atmosphere is made of 78% N2, 21% O2, 1% Ar, 0.4% H2O and <0.1% of other gases with carbon dioxide at 0.041%. If carbon dioxide levels are 'low' compared to the rest of the gases in the air, why is it always talked about? The gas is rising in airborne concentrations steadily since data was first taken in 1960. A longitudinal study by the NOAA Earth System Research Laboratory has shown that from 1960 to today carbon dioxide levels have risen by 90 ppm (parts per million). This seemingly small increase could have devastating affects on our enviornment. Global temperatures have been rising from the increase in efficient green house gases such as carbon dioxide, but also notably methane and nitrous oxide. According to a 2018 study of temperature increases and it's affect on organsim ranges predict that at a 3.2 C change in average temperature will result in  geographic range loss greater than 50% for 49% of insects, 44% of plants, and 26% of vertabrates. This temperature is what most countries have accepted in emissions talks. With everything we know about greenhouse gases and their affect on our planet this is an unnexcusable reality we are facing in the near future.

Our group focused our research on lichen abundance and air pollution. It turns out that lichens can be used as bioindicators of air pollution as their abundance of both species and individuals is correlated with pollution rates. Using this knowledge we compared lichen in two spots around campus, the campus pond and the woods behind sylvan residences, and compared the data. Our results yielded no significant difference in lichen abundance between the two spots. Thus we conclude either there is no difference in air pollution between these areas on campus or because we used trees near the outskirts of the sylvan woods they may not have been representative of the area.

Nutrient cycles in an ecosystem move the key components organisms need to survive. Nutrients generally enter a system through 2 channels. Either the weathering of abiotic materials that release the nutrients from its previous form or atmospheric inputs such as deposition and fixation. These nutrients are then soluble and can be absorbed by plants and microorganisms. Plants and microorganisms end up as detritus after their life cycles are terminated. Before becoming detritus some of these individuals will be consumed by heterotrophs which also inevitably become detritus. After time is allowed to pass the detritus decomposes and the nutrients mineralize and enter the soluble pool again. During this process, some of the nutrients are lost. The nutrients can become leached into the soil or be released into the atmosphere as a gaseous loss. This process repeats as long as nutrients are present in the active pools. If the nutrients stop cycling the ecosystem could experience catastrophic loss in biodiversity.

In order to visualize the available energy and biomass at each trophic level, ecologists use the pyramid model. At each trophic level, beginning with the primary producers on the bottom, a rectangle is made proportional to its value in that ecosystem. In terrestrial ecosystems, the energy and biomass pyramids decrease as each trophic level progresses. The primary producers have the most of both and the tertiary consumers are at the top with the least of both values. Aquatic ecosystems share a similar energy pyramid where the primary producers have the greatest amount and the tertiary consumers have the least. However, the biomass pyramid shows a different pattern. At the lowest trophic level, the primary producers, there is the least amount of biomass and as the trophic levels increase the biomass increases. This is known as an inverted pyramid. A pyramid such as this one occurs in aquatic ecosystems because the turnover rates of the primary producers are much higher. In terrestrial ecosystems, a lot of the biomass is inedible so the turnover rates are slower. 

From small mosses to large trees, all flora on earth requires water to survive. So what were to happen if an environment experienced an extreme drought? Could life survive? Some plants have developed methods of preventing their death due to water loss, a state which is also known as desiccation. Living cells would normally shrivel up and cease to function, however, some have become tolerant to that stress. These desiccation-tolerant plants produce proteins and morphological changes in response to low water levels. In a desiccation-tolerant plant, its cells synthesize sugars such as trehalose and transport them to cells who are experiencing shrinkage. Trehalose replaces the water and maintains membrane integrity. Another problem desiccation-tolerant plants face is how to repair damage to UV light and radiation when in this low metabolic state. The solution; produce pigments and extracellular sugars to block the incoming rays before they become a problem. 

All flora on earth requires water to survive. From small mosses to large trees, water is essential to life on earth. So what were to happen if an environment experienced an extreme drought? Could life survive? It turns out many plants have developed methods of preventing their death due to water loss, also known as desiccation. These desiccation-tolerant plants produce proteins and morphological changes in response to low levels of water. Cells are mostly made of water so in the case of water loss they would shrivel up and cease to function. In a D-Tolerant plant, sugars such as trehalose are synthesized and transported to cells who are experiencing shrinkage. They replace the water and maintain membrane integrity. A problem these plants face is how to repair damage to UV light and radiation when in this low metabolic state. One solution is to simply produce more pigments and extracellular sugars to block the incoming rays before they even become a problem.

Basic principles of biological evolution say the organism most suited for its environment will win out over other organisms and no two organisms can inhabit the same niche. Why is it then that planet earth houses such incredible biodiversity? Shouldn't there be a few dominant species and maybe some stragglers? Well, it turns out many species have been able to co-exist with other similarly functioning species by partitioning their resources. There are two ways this can be accomplished. First is through specialization. If in an ecosystem, there are different sizes of the same food then different organisms may slowly develop adaptions that would allow them to better capitalize on a specific part of that food. For example, some birds may develop beaks better designed for small seeds while others could go for large seeds. Both species are feeding on seeds, however, the size of the seed is divided. The second way is through broadening the food types. If there is an increase in variability of the necessary resource then more species can be included in the partitioning. It is important to keep in mind that neither of these methods is based on altruism. Life on earth always looks out for its best interest.

One model of ecological succession is facilitation. This mechanism takes place when a large disturbance has taken place in an environment rendering it useless to the organisms who once called it home. A pioneer species able to survive in this environment gains a foothold and begins to transform its surroundings by simply existing. The type of change it may produce will likely be in favor of its own species while simultaneously making the habitat not suitable for other species. After some time this initial species has become a prominent figure in the budding ecosystem, however, the modifications to the environment have made it ideal for other species. With their upcoming, the pioneer species population may be reduced in size until there is little to none left. The dominant species could not have lived in this environment if it weren't for the pioneer species. For this reason, the model was named 'facilitation, as one pioneer species facilitated the means by which another organism can come up.

Water is one of the fundamental molecules plants, and all organisms for that matter, need in order to survive. Basic photosynthesis, turgor pressure, and many other processes would not be possible without water. So how is water brought into the plant? Plants uptake their nutrients through root systems that tunnel in the soils below. Some plants branch out more than others, however, all of them have thousands of small single-celled root hairs extending into the soil. These root hairs increase the surface area of the roots and provide pathways for nutrients to diffuse into. One of these being water molecules. Once in the root, there are three ways water can reach the xylem, the water transport cells. First is through the apoplast. This area is the space in between cells that cannot regulate what passes by. Eventually, this pathway meets a lignin barrier separating it from the xylem where it must enter a cell in order to pass. The second and third ways are through channels within cells. These are either by aquaporins or transmembrane channels that water molecules can pass through. Eventually, water will again reach the lignin barrier which it can pass without much extra movement as it is already in the cell.