Vegetation Responses to Drought and Nitrogen Deposition in a Cool Desert Ecosystem

Biome Classification and Desert Biomes

Task:

This is an ‘open book’ exam and you may use any materials you need to support your answer. Each exam will be run through a plagiarism program. If you have any questions as to what plagiarism is one of the best sources to look at is plagiarism.org. You are responsible for knowing and understanding what plagiarism is.

Each question has multiple parts so please make sure you have addressed all the points of each question. You will be evaluated not only on your answer to each question but also on your clarity in writing, logical presentation of ideas, in addition to grammar, spelling and punctuation. You have been asked to use references in some of the questions. Please use APA format when citing references. In scientific writing the use of quotes is rarely used. For these essays, there will be no reason to use quotations. Thus you are not allowed to use quotes in any of your responses.  I strongly encourage you to use any illustrations and/or conceptual models to support your essays.

As an undergraduate research assistant you would like to conduct a study on the Colorado Plateau to examine “Vegetation Responses to Drought and Nitrogen Deposition in a Cool Desert Ecosystem.” Both drought intensity and frequency are expected to increase with changing climate over the next century across this region. In addition to changes in drought, there has been increasing levels of nitrogen deposition especially near urban areas. Following this you would like to get funding for your honors thesis project to examine the potential impacts of drought and nitrogen deposition on plant growth. The Nature Conservancy manages the Canyonlands Research Center (CRC) near Canyonlands National Park and you would like to conduct your experiment on CRC lands. You need to sell your research idea to the science and management advisory committee. In this essay, I would like you to put together the main ideas for your proposal that will be submitted to the advisory board. 

The advisory board is a group of scientists and land managers. You will be evaluated on your ability to communicate complex ideas regarding your research in a manner that is easily understood by people not trained in the sciences. Put simply, if you copy highly technical definitions from a book you won’t receive credit.  The ideas that are covered are outlined below.  Please cite all literature in APA format at the end of your essay. (60 POINTS)

A.In a brief introduction discuss the concept of the biome classification, how biomes are distribute globally and some important characteristics of and threats to desert biomes.


B. In order to understand what limits plant growth it is first important to understand how plants produce organic molecules to support the functioning of the plant system. In this section you want to explain to your audience the fundamental concepts related to plant photosynthesis. You will need to start by 1) defining photosynthesis and go on to then explain the 2) light dependent reaction in photosynthesis and 3) the manner in which carbon fixation (i.e. Calvin Cycle) occurs in photosynthesis.


C. You have explained how photosynthesis works so you now need to make the connection to plant growth. You should first explain the potential fate of carbon fixed in photosynthesis and go on to discuss why there may not always be a strong correlation between net photosynthetic rates and plant growth.
 
D. In this next section you need to give your audience some background on water as a factor that limits plant growth in this cool desert ecosystem. Please explain 1) why water is important for plants giving one example of the importance of water to plant function 2) how water moves from the soil system through the plant and to the atmosphere 3) and the trade-offs between water loss and CO2 uptake describing how these are under the control of the plant.

E.In this section you need to give your audience some background on nutrient limitation to plant growth in this cool desert ecosystem. You first should provide background on plant mineral nutrition. Please 1) list the macro and micronutrients that are important for plant function 2) describe the process/es by which nutrients are delivered to the plant discussing the importance of each process 3) choose one element that is limiting to plant growth in terrestrial ecosystems globally and explain how this element is important for plant function 4) then finish by giving one example of mechanism by which plants are able to increase their uptake of this element.

F. In this final section you should formulate two hypotheses. The first hypothesis should included plant growth response to drought. The second hypothesis should include plant growth response to nitrogen deposition. Building on your hypotheses, briefly explain the experimental approach you will take to examine the impacts of drought and nitrogen deposition on plant communities in this cool desert ecosystem. Please cite at least four primary journal articles that support your hypotheses related to water and nutrients. In your experiment you need to identify the factor/s that you are going to manipulate to examine plant responses to drought and nitrogen deposition (independent variable/s) and at least two measurable response variables. I am not looking for descriptions of an experimental design that includes replication or statistical analyses. Just provide a more generalized experimental approach.

2. Global average surface warming is projected to increase in the range of 1.8-4.0°C by the end of the century. I would like you to write an essay discussing C3 and C4 photosynthetic pathways in response to future climate. In this essay give background on: A) the evolution of C3 and C4 photosynthetic pathways B) explain the fundamental differences in these two photosynthetic pathways at the biochemical level 3) two potential advantages C4 plants have over C3 plants and the 4) current distribution of C3 and C4 plants globally.  Following on this background I would like you to make a prediction on how these differences in photosynthetic pathways may play out in a world experiencing temperature increases along with increasing atmospheric CO2 concentrations. You need to support your prediction with at least 3 citations from the primary literature. You need to end your essay by outlining the difficulties in predicting who will “win” under future climate change.