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Smith Lab News

July 21, 2018:

Nick spent the week in Indiana resampling plots at the Prairie Invasion and Climate Experiment (PRICLE).

PRICLE was nitrogen addition by rainfall variability experiment that ran from 2012-2014. The experiment was located in a mixed-grass prairie dominated by Canada goldenrod (Solidago canadensis) and little bluestem (Schizachyrium scoparium). The treatments acted to synergistically reduce plant species diversity and evenness by promoting the dominance of S. canadensis.

Although the experimental treatments ended after the 2014 growing season, the plots were kept in place. Nick resampled the plots this week to examine whether the short-term effects of the treatments persisted after the manipulations ended. That is, were the effects transient or did they result in a permanent change to the plant community?

Stay tuned for the answer!

Nick also got to check out a giant rainfall exclusion experiment in a cornfield! Lots of cool stuff going on at the old stomping grounds!

July 11, 2018:

Nick, along with TTU Biology professors John Zak and Natasja Van Gestel, spent the morning at RN Hopper's farm in Petersburg, TX. They were there with an engaged group of South Central Climate Science Center interns to learn about the impact of alternate management practices on plant and soil health. At the farm, we discussed how "unconventional" management practices such as no-till, dryland, cover cropping, and rotation cropping can reduce costs and increase yields. The students, underrepresented minority undergraduates or recent graduates, came from all over the South Central United States as part of a 3-week internship that includes trips to Texas Tech, the University Oklahoma, Oklahoma State University, and Louisiana State University. As part of their stay at TTU, they will be learning everything from biology to climate modeling to climate communication to social and ethical issues surrounding climate science.

July 3, 2018:

Check out a new paper from the lab, led by colleague Danica Lombardozzi (NCAR), entitled "Triose phosphate limitation in photosynthesis models reduces leaf photosynthesis and global terrestrial carbon storage." The unformatted version of the paper came out in Environmental Research Letters last week. The paper examines the sensitivity of models to TPU limitation, the understudied third limitation of photosynthesis. We find that leaf photosynthesis and global terrestrial biosphere models are sensitive to how TPU limitation is parameterized. For the leaf model, TPU limitation becomes more important at cold temperatures, high CO2 levels, and high light levels. In a global model, the implementation of increased TPU limitation has a negative impact on simulated terrestrial carbon uptake and storage under present-day and future climates. However, while we find TPU is an important process limiting photosynthesis globally, we note that it is highly understudied. We need further experiments dedicated ot understanding TPU under various conditions and the acclimation of this process in particular.

May 23, 2018:

Summer means time for Soybeans and new Students for Lizz's project. Welcome to the lab Angel, Leah, and Zachary!

Some of the full sun soybeans in the greenhouse

Lizz showing Angel (left) and Leah (center) how to scan leaves

Angel (left), Zachary (Center) and Leah (right) grinding leaves for elemental analysis

May 17, 2018:

As part of his editorial duties at the new journal Forest Ecophysiology, Nick will be editing a research topic entitled Physiological Acclimation to Global Change . The collection of articles will examine acclimation responses of forest species to global changes happening now and expected in the future. If you work in this field, consider submitting!

May 7, 2018:

The cotton growing portion of Lizz's light by nitrogen greenhouse experiment has been completed! Time to switch to soybeans and collect elemental data and leaf trait data in the lab!

The last of the cotton plants before biomass harvest. Which grew under high light and which had low light? Which grew with low N vs high N?

Using the Licor 6800s on some low light acclimated cotton

Undergraduate researcher Austin taking care of washing cotton roots

May 4, 2018:

We took our first Mesquite measurements at out NutNet site! We also gathered leaves for C/N and measured LAI in each plot. Data is officially flowing in!

May 1, 2018:

Here are a few images from the journey that produced out new paper in Ecology. I really wish that I was a better photographer!

Donald E. Davis arboretum

Grandfather mountain (not sampled)

Blandy Experimental Farm

Morgan Monroe State Forest

Kellogg Biological Station

Kellogg Biological Station

Kellogg Biological Station

University of Michigan Biological Station

SE Purdue Ag Center

SE Purdue Ag Center

SE Purdue Ag Center

La Selva Biological Station

La Selva Biological Station

La Selva Biological Station

La Selva Biological Station

Apr 30, 2018:

Nick just had a new paper published in Ecology entitled "Drivers of leaf carbon exchange capacity across biomes at the continental scale." The paper examines the factors that influence photosynthetic and leaf respiratory traits across a variety of different plants and ecosystems. The study uses the LCE dataset to drive the analyses. The dataset includes leaf gas exchange and trait data from 98 species spanning a 53° latitudinal gradient from Costa Rica to Alaska.

The study finds that recent temperature and soil moisture interact to influence photosynthetic capacity. In dry areas, photosynthetic capacity is reduced with warming, but the downregulation trend is not apparent in wetter areas. This finding may reconcile meta-analytical studies that have found both a downregulation (Ali et al., 2015) and no response (e.g., Kattge and Knorr, 2007) of photosynthetic capacity to warming. The results also indicate that photosynthesis is more responsive to short-term (weekly) changes in temperature and soil moisture than it is to long-term climate. On the other hand, leaf respiratory capacity is less variable than photosynthesis and more responsive to long-term climate.

In the Smith lab and with a global group of collaborators, we are now working on developing theoretical models to predict these responses from first principles. Stay tuned for more to come!

You can access the article from Ecology's website here.

Figures from the paper:

Apr 27, 2018:

Our NutNet plots are now marked with permanent posts. Once things green up we will begin taking some preliminary measurements. Treatments are scheduled to go in next year. The orange flags in the picture are marking buried resin bags. We are excited to have Juan Garcia-Cancel, a visiting PhD student from the TTU Natural Resources Management department, tracking nutrient flow at our site. Also, the Mesquite is starting to flower!

Also, the Mesquite is starting to flower!

Apr 6, 2018:

The mesquite trees are beginning to leaf out at our NutNet plots. Check out the thorns on those guys! The pink flags in the background are initial markers for the NutNet plots. We hope to have something more permanent in soon!

Mar 19, 2018:

Lizz's light by Nitrogen addition experiment is up and running! She is examining the relative influence of light and N on leaf- and whole plant-level processes. This (relatively) simple experiment will help us better understand how N influences productivity. We hope to use her results to improve the processes represented in Earth System Models.

Mar 18, 2018:

The Smith Lab was just approved to set up a Nutrient Network (or "NutNet" ) site in Lubbock! Along with the core measurements, we will specifically focus on physiological responses to nutrient addition in West Texas Rangeland species. Get in touch if you'd like to collaborate!

Mar 16, 2018:

Check out our new Eos meeting report on modeling global change ecology. The report, led by Susan Cheng with help from Nick and Alison Marklein, examines major topics of discussion from our ESA ignite session last August.

Spring 2018:

We have students in the lab! Mahum Haque, undergraduate (Biological Sciences), will be examining chlorophyll allocation under different light and N environments. Austin Cooper, undergraduate (Biological Sciences), will be examining biomass and nutrient partitioning under different light and N environments. Jorge Orchoa, undergraduate (Natural Resource Management), will be helping to set up our new NutNet experiment. Josh Gutierrez, undergraduate (Biochemistry), will be helping Lizz mix and apply different fertilization treatments in her greenhouse experiment.

Jan 17, 2018:

We just published an new study in Annals of Botany - Plants. The study comes out of the Boston Area Climate Experiment (BACE), a warming by precipitation manipulation experiment in Waltham, MA. In the study, led by Vikki Rodgers, we examined seedling trait responses (from leaf- to whole-plant scale) to the treatments and found that warming exacerbated plant sensitivity to rainfall. These results are consistent with other results at BACE that suggest that warming, while beneficial under high rainfall, can induce water loss that can exacerbate the negative impacts of low rainfall on ecosystem functioning. See PI Jeff Duke's publications for more results from the BACE.


2017 Archive