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Grantee Research Project Results

Grantee Research Project Results

Impacts of increased precipitation and nitrogen deposition on desert plant carbon dynamics at Big Bend National Park, Texas

EPA Grant Number: F5F61403
Title: Impacts of increased precipitation and nitrogen deposition on desert plant carbon dynamics at Big Bend National Park, Texas
Investigators: Patrick, Lisa
Institution: Texas Tech University
EPA Project Officer: Zambrana, Jose
Project Period: August 1, 2005 through September 1, 2008
Project Amount: $97,400
RFA: GRO Fellowships for Graduate Environmental Study (2005)
Research Category: Academic Fellowships

Description:

Objective:

I will study the effects of changes in global climate on desert plant biodiversity at Big Bend National Park, Texas. More specifically, I will investigate how increased precipitation and nitrogen deposition will alter the carbon dynamics of the dominant plants in a sotol-grassland ecosystem. Alterations in environmental conditions may change the amount of carbon used by plants for important processes such as photosynthesis, respiration, and the construction of vegetative and reproductive parts. By studying the physiological responses of plants to global climate change, I hope to better understand future changes in plant species' success and biodiversity.

Changes in the global climate system due to increased levels of CO2 and other greenhouse gases are predicted to have a significant impact on arid and semi-arid ecosystems. Global climate models predict that the timing and amount of precipitation will vary, as well as nitrogen deposition patterns, both of which are anticipated to affect plant carbon acquisition, allocation and growth. This project will address the effects of increased precipitation and nitrogen deposition on the desert plant community at Big Bend National Park, Texas. The objective is to determine the effect of changes in precipitation and nitrogen deposition on the overall aboveground carbon balance of the dominant plants in a sotol-grassland ecosystem.

Approach:

In order to determine the carbon balance for a plant, I will measure:

  1. the net energy gained by the system (i.e. individual plant) as the difference between plant photosynthesis (i.e. carbon flux into the system) and plant respiration (i.e. carbon flux out of the system,
  2. and the system energy utilization as plant construction cost (i.e. carbon used to produce plant biomass).

In order to understand the overall response of this sotol-grassland ecosystem, I will develop a model to relate changes in individual plant energetics to community and ecosystem level species’ success.

I plan to study the effects of changes in our global climate on desert plant biodiversity at Big Bend National Park, Texas. More specifically, I will investigate how increased precipitation and nitrogen deposition will alter the carbon dynamics of the dominant plants in a sotol-grassland ecosystem. Alterations in environmental conditions may change the amount of carbon used by plants for important processes such as photosynthesis, respiration, and the construction of vegetative and reproductive parts. By studying the physiological responses of plants to global climate change, I hope to better understand future changes in plant species' success and biodiversity.

Expected Results:

Increased precipitation and nitrogen deposition will increase the net carbon gain of the study plants due to increased rates of photosynthesis. The energetic cost for biomass production (i.e. construction cost) of the plant will not be immediately or greatly affected by increased precipitation, but may decrease with increased nitrogen deposition. Overall, I expect that changes in individual plant responses to increased precipitation and nitrogen deposition will have the potential to alter community and ecosystem level species’ success. I predict that species which can increase carbon gain due to the acquisition of increased water will not only become the dominant members of the community, but also show long term persistence and success in the ecosystem. I further predict that increased nitrogen will not have a large effect on community dynamics unless coupled with increased precipitation, as water is essential for the assimilation of nitrogen by plants.

Supplemental Keywords:

Big Bend National Park, Chihuahuan Desert, competition, construction cost, global climate change, grassland, nitrogen, photosynthesis, physiology, precipitation, respiration,, RFA, Scientific Discipline, Air, INTERNATIONAL COOPERATION, climate change, Air Pollution Effects, Environmental Monitoring, Atmosphere, Global Climate Change, carbon sequestration, atmospheric nitrogen, atmospheric carbon dioxide, biodiversity, climatic influence, consequences of vegetation change, desert plants, green house gas concentrations, precipitation patterns, grassland ecosystem, carbon dioxide, CO2 concentrations

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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