Our research centers around the physiology and ecology of trees and other woody species. We are particularly interested in water transport in plants, which is essential for plant survival. Plant water transport properties are directly related to plant distributions and plant carbon capture (and many other things).

Research

Leaf Hydraulics Research

We are interested in the pathway of water movement inside leaves. The bottlenecks for water flow through leaves has only recently been explored and there is a lot left to figure out! Since the leaf is the organ that is primarily responsible for controlling the water balance of the plant, this is a critical area of research.  Check back soon for some very cool images.....

Whole Plant Hydraulics

We are interested in the water transport properties of entire plants - leaves, branches, roots, trunks. Sometimes this means sampling destructively, but hey, it's for science.

The vast majority of our understanding of plant hydraulics is based on studies of terminal branches. This offers us a very limited understanding of how water moves through whole plants and how drought might affect whole plants.

The above image shows one way of measuring embolism (air bubble formation) in leaf xylem - this method is acoustic emission (super-sensitive microphones). Below is a set of tropical liana stems being prepared for hydraulic measurements.

Seedlings

In nature, most newly-germinated seedlings die.

Mortality in young seedlings is typically >99%!

In order for species to migrate with climate change, seedlings have to establish beyond the current species boundary. Yet, the newly germinated seedling stage is the life stage of trees that we know least about.  We are currently studying the physiology and anatomy of newly-germinated seedlings as they develop during their first year of life.

Drought

Severe droughts are predicted to become more frequent with climate change. Northern Idaho experienced its worst drought on record in 2015 (record keeping began in 1895) and central TX experienced its worst drought in over 1200 years in 2011-2015.

We are trying to understand what this might mean for different tree species in different habitats. Above is an image showing the impact of the 2011-2015 Texas drought. This picture was taken in July of 2013 - everything in grey is dead. We are also working on what happens after drought when precipitation returns. For example, is there a physiological legacy of drought or do plants just go back to business as usual? 

We are using field- and greenhouse-based studies, along with process-based models, to try to understand the mechanisms of drought induced mortality and plant responses to drought alleviation. 

Select Publications

Visit my Google Scholar page

2022

Johnson DM, Katul G, Domec JC. 2022. Catastrophic hydraulic failure and tipping points in plants. Plant, Cell and Environment (accepted, in press)

Benson MC, Miniat CF, Oishi AC, Denham SO, Domec JC, Johnson DM, Missik JE, Phillips RP, Wood JD, Novick KA. 2022. The xylem of anisohydric Quercus alba L. is more vulnerable to embolism than isohydric co-dominants . Plant, Cell and Environment (accepted, in press)

Trueba S, Theroux-Rancourt G, Earles JM, Buckley TN, Love DM, Johnson DM, Brodersen C. 2022.The 3d construction of leaves is coordinated with water use efficiency in conifers. New Phytologist 233:851-861.

2021

Mrad A, Johnson DM, Love DM, Domec JC. 2021. The roles of conduit redundancy and connectivity in xylem hydraulic functions. New Phytologist 231:996-1007.

Domec JC, King JS, Carmichael MJ, Overby AT, Wortemann R, Smith WK, Maio G, Noormets A, Johnson DM. 2021. Root water gates and not changes in root structure provide new insights into plant physiological responses to drought, flooding and salinity. Journal of Experimental Botany 72:4489-4501.

Sonawane BV, Koteyeva N, Johnson DM, Cousins A. 2021. Differences in leaf anatomy determines temperature response of leaf hydraulic and mesophyll CO2 conductance in phylogenetically related C4 and C3 grass species. New Phytologist 230:1802-1814.

Hammond WM, Johnson DM, Meinzer FC. 2021. A thin line between life and death: radial sap flux failure signals trajectory to tree mortality. Plant, Cell and Environment 44:1311-1314.

Feltrin RP, Smith AMS, Adams HD, Kolden CA, Johnson DM. 2021. Short- and long-term effects of fire on stem hydraulics in Pinus ponderosa saplings. Plant, Cell and Environment 44:696-705.

2020

Feltrin RP, Johnson DM, Sparks AM, Adams HD, Kolden CA, Nelson AS, Smith AMS. 2020. Drought increases vulnerability of Pinus ponderosa saplings to fire-induced mortality. Fire 3:56.

Miller ML, Roddy AB, Brodersen CR, McElrone AJ, Johnson DM. 2020. Anatomical and hydraulic responses to desiccation in emergent conifer seedlings. American Journal of Botany 107:1177-1188.

Halbritter AH, De Boeck HJ, plus 113 co-authors (including DMJ). 2019. The handbook for standardized field and laboratory measurements in terrestrial climate-change experiments and observational studies (ClimEx). Methods in Ecology and Evolution 11:22-37.

 

TimberMart-South publishes quarterly and annual reports used by private companies, consultants, landowners, and others to assess market prices in the US South. We have been surveying and reporting timber prices since 1976, and market news since 1996. 

Our quarterly news and prices are available by subscription or by individual issue to provide information on timber market changes in the US South as well as average prices in 22 areas of the southeastern timber markets.

The Harley Langdale Jr. Center for Forest Business webpage has moved. Visit https://cfb.uga.edu/ for more information about the center and its programs.

The University of Georgia’s Harley Langdale Jr. Center for Forest Business integrates pioneering academic research and sound financial methods to provide education and service to forest industry, investors, and landowners throughout the world.

Established in 1997, the center's mission is to provide national leadership in education, research, and service to forest industry, private landowners, and Georgia in:

• The integration of sound forest business principles and practices with contemporary biological and quantitative methods to achieve sustainable forest production
• The investigation of forest resources and forest industry alternatives that are economically competitive in the global marketplace
• The proposal of market-based solutions to forest resource problems and opportunities

Education

The Center for Forest Business offers a graduate-level educational program leading to a Master of Forest Resources (MFR) in Forest Business. This degree is designed to launch your career in a position of leadership in forest operations management, timberland investing, or education in the private or public sector.

Learn More About This Degree Program

Service

The Center for Forest Business serves the forest business community by coordinating and implementing the Sustainable Forest Initiative, in addition to hosting regular educational conferences in forestland investing, economics, and finance. This program oversees several continuing education initiatives:

• Master Timber Harvester logger education program
• Landowner and public outreach
• Inconsistent Practices Hotline

We also produce products to assist landowners and industry professionals in valuation, taxes, and other topics affecting the forest industry. Download our recent guides:

• Handbook of Land and Tree Measurements
• 2021 Current Use Values for Georgia Conservation Use (CUVA) Land and Forest Land Protection Act (FLPA) Land
• Qualified Timber Property guide

View the Full List of Publications

Research

Our research focuses on issues critical to all aspects of forest business, and especially sustaining and enhancing the competitiveness of Georgia’s wood fiber supply.

Fiber supply assessment studies estimate present and future forest inventories, including:

• Acquisition and analysis (spatial and not) of Forest inventory related data;
• Development and implementation of inventory projection models; and
• Spatially explicit simulations of inventory dynamics under varying assumptions.