How do plants manage the tradeoff between carbon and water on a changing planet?

All organisms are built to obtain the resources necessary for survival. But in most cases, obtaining one resource comes at the expense of another. For plants, obtaining carbon from the air comes at the expense of losing water. Our work explores the structure and process of plants that governs this tradeoff.

But there is also a twist…climate change is altering the relationship plant structure and function have to climate. Rainfall, temperature, sunlight, and humidity changes alter plant function and, for some, their ability to survive. Our work finds novel mechanisms of plant function and uses that to find strategies that may work on a changing planet.

Our work spans cellular to ecosystem approaches and takes us to many unique ecosystems: temperate to tropics, savannas to rainforests, coasts to mountaintops.

Our work has three goals: (1) explore novel processes in plants, (2) understand plant strategies for managing acute stress (i.e. drought), and (3) develop new tools for researchers to probe previously unanswered questions.

The effect of drought in Texas. Everything that is grey is dead from drought

Novel Processes in plants

We have learned a great deal about how organisms function, but there is still a lot left to discover. Our work seeks out new ways of thinking about carbon and water management in plants: seeking out new pathways of flow or ideas that were previously understudied. Elucidating these processes has multiple purposes. First, it will reveal new approaches for how plants interact with their environment and allow for better predictions for the fate of species. Secondly, it creates new relationships between plants and their environment that allow for empirical modeling for the movement of carbon and water globally. Two projects tackle these questions:

How does carbon move through forests when canopies are wet? Are wet canopies barriers to carbon flows and photosynthesis or actually creating ideal conditions to optimize carbon gain? Can we model how carbon moves through wet canopies?

What are the mechanisms by which plants increase productivity under diffuse light conditions? Can we alter plant light-use strategies to take advantage of these diffuse light responses?

Plant strategies for managing stress

When stomatal pores on leaves open, plants create opportunities to obtain carbon, allowing them to grow and survive. But this opening leads to an outpouring of water; water needed by the plant for that growth and survival. Plants have build structures from roots to leaves to manage this tradeoff. Sometimes, they build risky structures, sacrificing a lot of water in hopes of growth. Other times, they build conservative structures, being methodical with carbon and water management. Climate change (drought, temperature, light) is pushing these strategies to the limit. Currently, we are tackling these questions in southern pine species trying to understand how plant traits respond to increasing drought stress. Some of our questions are:

How do southern pine species respond to long term drought stress? Do some physiological traits acclimate while others remain static? Are there interactions between drought response and other environmental conditions (fertilization, biotic interactions)? Do some species have different mechanisms that lead to greater concern for their survival under climate change? Can we use our results to inform land managers about new strategies?

New research Tools

Our ability to ask novel questions or create new ideas is hindered by our methods more than our creativity. In our group, as we create new questions, we also brainstorm novel methodological approaches to address those questions. This often expands our thinking into other fields: engineering, physics, chemistry, and math.

Recently, we developed an integrating sphere that interfaces directly with the LiCor 6800 portable photosynthesis machine and allows the user to manipulate the diffuse fraction of light.

We are also developing methods that will allow users to quantify the conductance of leaves when they are wet.

Both approaches open new doors for scientists and provide opportunities to ask an array of questions that we could not tackle previously.