Throop Lab Research

A smattering of current and past research projects.

Woody encroachment influences on carbon and nitrogen pools and processes
There has been a dramatic increase in the abundance and cover of woody plants (trees and shrubs) in grasslands and savannas globally over the past century. This proliferation of woody vegetation, as well as management approaches to combat it (e.g., prescribed burning, herbicide application, and mechanical removal), strongly affect local, regional, and global C and N cycles.  We are currently involved in several different projects that use field studies and ecosystem modelling to explore how woody plants affect C and N pools and processes.  We are particularly interested in the role of spatial and temporal heterogeneity in these systems.  Ongoing work in this area, funded by an NSF CAREER grant, explores the source and stability of C inputs to soil C pools.  This work takes place at the Santa Rita Experimental Range, Jornada Basin LTER, Sevilleta LTER, and other sites.

Examples of this research:
- Throop & Archer 2008 Global Change Biology
- Throop et al. 2013 Biogeochemistry

Dryland decomposition 

Litter decomposition is an important biogeochemical process. The controls over decomposition are poorly understood in arid and semi-arid systems (drylands) relative to mesic systems.  Recent work suggests that abiotic drivers of decomposition such as UV photodegradation and soil-litter mixing may play a unique role in dryland decomposition.  We are conducting a series of laboratory and field experiments to explore these drivers.  Field work takes place at the Santa Rita Experimental Range, Jornada Basin LTER, and Sevilleta LTER.

Examples of this research:
- Throop & Archer 2007 Ecological Applications
- Lee et al. 2012 Global Change Biology
- Barnes et al. 2015 Progress in Botany

NSF Decomposition Project Web Site

Global change influences on arid systems
Dryland systems are expected to be strongly affected by future changes in climate. We have several projects exploring the impacts of changing precipitation regimes on plant ecophysiology, litter decomposition, and carbon cycling.  We are also working across rainfall gradients in Australia and Namibia to understand moisture controls over carbon cycling.

Example of this research:
Throop et al. 2012 Oecologia
de Graaff et al. 2014 Ecosystems

Carbon cycling in Australian woodlands
In collaboration with David Eldridge (University of New South Wales), we are exploring relationships between vegetation cover and soil carbon pools in arid and semi-arid woodlands in New South Wales. We are interested in understanding how these relationships respond to precipitation, the abundance of introduced and native animals, and land management. These questions are particularly interesting in Australia at present due to the recently instituted (and quickly rescinded!) carbon tax. Carbon taxation measures potentially provide new economic incentives for land management strategies that change carbon uptake or release patterns, but we currently have limited means to monitor or estimate landscape carbon uptake and store patterns.

Example of this research:
Smith et al. 2012 Plant and Soil
Daryanto et al. 2013 Agriculture, Ecosystems and Environment

Animal influences on ecosystems
One of my long-term intellectual curiosities has been exploring the extent to which animals typically influence ecosystem processes. I first started thinking about this for my dissertation research (with Manuel Lerdau in the Department of Ecology and Evolution at SUNY Stony Brook), where I assessed the influence of insect herbivory in combination with atmospheric nitrogen deposition on plant physiology, growth, and reproduction. I adapted CENTURY, a process-based ecosystem model, to include mathematical functions that describe herbivore responses to deposition-induced changes in plant tissue chemistry.

More recently, Jen Funk and I explored whether patterns of structural and chemical defense differ for native and invasive plant species in Hawai’i. Currently, we have two projects exploring the impact of small mammals on soil carbon pools.  We are fortunate to be able to work in The Portal Project in southwestern Arizona. Thanks to all the past and present researchers at this site who have maintained this long-term manipulative study! We are also quantifying the impact of wood rat middens on soil carbon cycling at the Jornada Basin LTER.

Examples of this research:
- Throop & Lerdau 2004 Ecosystems
- Throop et al. 2004 Global Change Biology
- Funk and Throop 2010 Oecologia

The Throop Lab employs and advises a small number of highly motivated undergraduate and graduate students. Check out our Information for Prospective Students.