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Donald Schoolmaster, Ph.D.
Don Schoolmaster's research focuses on the use quatitiative tools to combine ecological theory and data to address important applied questions. Two major avenues his work takes is 1) Using theory in inform causal networks (such as structural equations) that can be tested with data. His work in this area included both the development of methods, such as advanced methods for Structural Equation Modeling (SEM) and applying these method to address ecological problems. 2) Using ecological theory to inform tools of ecological assessment. The methods used to develop quantitative tools such as Ecological Indicators (EI) and Multimetric Indices (MMI) often imply causal assumptions. The usefulness of the final assement tool will often depend critically on how well these assumptions are met. Schoolmaster works to develop quatitiative assement methods that have causal assumptions that are met by ecological theory and expert opinion to insure a match between the assessment tool and understanding of how the systems works.
Science and Products
Influence of Sea-Level Rise on Wetland Vegetation Community Structure, Primary Productivity, Organic Matter Decomposition and Carbon Storage
This study will employ a space for time substitution to show long-term effects of rising sea-level and increasing salinity on vegetation community structure, primary production and decomposition. Productivity and decomposition rates will be estimated for four wetland plant community types defined by salinity zones and dominant plant species.
Land area change in coastal Louisiana (1932 to 2016)
Coastal Louisiana wetlands are one of the most critically threatened environments in the United States. These wetlands are in peril because Louisiana currently experiences greater coastal wetland loss than all other States in the contiguous United States combined. The analyses of landscape change presented here have utilized historical surveys,...Couvillion, Brady R.; Beck, Holly; Schoolmaster, Donald; Fischer, Michelle
Causal mechanisms of soil organic matter decomposition: Deconstructing salinity and flooding impacts in coastal wetlands
Coastal wetlands significantly contribute to global carbon storage potential. Sea-level rise and other climate change-induced disturbances threaten coastal wetland sustainability and carbon storage capacity. It is critical that we understand the mechanisms controlling wetland carbon loss so that we can predict and manage these resources in...Stagg, Camille L.; Schoolmaster, Donald; Krauss, Ken W.; Cormier, Nicole; Conner, William H.
Soils mediate the impact of fine woody debris on invasive and native grasses as whole trees are mechanically shredded into firebreaks in piñon-juniper woodlands
To stem wildfires, trees are being mechanically shredded into firebreaks with the resulting fine woody debris (FWD) potentially exerting immense control over soil and plants. We linked FWD-induced changes in microbial activity and nutrient availability to the frequency of Bromus tectorum and three native, perennial grasses across 31 piñon-juniper...Aanderud, Zachary T.; Schoolmaster, Donald R.; Rigby, Deborah; Bybee, Jordon; Campbell, Tayte; Roundy, Bruce A.
A landscape-scale assessment of above- and belowground primary production in coastal wetlands: Implications for climate change-induced community shifts
Above- and belowground production in coastal wetlands are important contributors to carbon accumulation and ecosystem sustainability. As sea level rises, we can expect shifts to more salt-tolerant communities, which may alter these ecosystem functions and services. Although the direct influence of salinity on species-level primary production has...Stagg, Camille L.; Schoolmaster, Donald R.; Piazza, Sarai C.; Snedden, Gregg; Steyer, Gregory D.; Fischenich, Craig J; McComas, Robert W.
Barrier displacement on a neutral landscape: Towards a theory of continental biogeography
Macroevolutionary theory posits three processes leading to lineage diversification and the formation of regional biotas: dispersal (species geographic range expansion), speciation (species lineage splitting), and extinction (species lineage termination). The Theory of Island Biogeography (TIB) predicts species richness values using just two of...Albert, James S.; Schoolmaster, Donald; Tagliacollo, Victor; Duke-Sylvester, Scott M.
Do the rich get richer? Varying effects of tree species identity and diversity on the richness of understory taxa
Understory herbs and soil invertebrates play key roles in soil formation and nutrient cycling in forests. Studies suggest that diversity in the canopy and in the understory are positively associated, but these studies often confound the effects of tree species diversity with those of tree species identity and abiotic conditions. We combined...Champagne, Juilette; Paine, C. E. Timothy; Schoolmaster, Donald; Stejskal, Robert; Volařík, Daniel; Šebesta, Jan; Trnka, Filip; Koutecký, Tomáš; Švarc, Petr; Svátek, Martin; Hector, Andy; Matula, Radim
Scaling relationships among drivers of aquatic respiration from the smallest to the largest freshwater ecosystems
To address how various environmental parameters control or constrain planktonic respiration (PR), we used geometric scaling relationships and established biological scaling laws to derive quantitative predictions for the relationships among key drivers of PR. We then used empirical measurements of PR and environmental (soluble reactive phosphate [...Hall, Ed K; Schoolmaster, Donald; Amado, A.M; Stets, Edward G.; Lennon, J.T.; Domaine, L.; Cotner, J.B.
Structural equation modeling: building and evaluating causal models: Chapter 8
Scientists frequently wish to study hypotheses about causal relationships, rather than just statistical associations. This chapter addresses the question of how scientists might approach this ambitious task. Here we describe structural equation modeling (SEM), a general modeling framework for the study of causal hypotheses. Our goals are to (a)...Grace, James B.; Scheiner, Samuel M.; Schoolmaster, Donald R.
Connecting the dots: a collaborative USGS-NPS effort to expand the utility of monitoring data
The Natural Resource Challenge (National Park Service 1999) was a call to action. It constituted a mandate for monitoring based on the twin premises that (1) natural resources in national parks require active management and stewardship if we are to protect them from gradual degradation, and (2) we cannot protect what we do not understand. The...Grace, James B.; Schoolmaster, Donald R.; Schweiger, E. William; Mitchell, Brian R.; Miller, Kathryn; Guntenspergen, Glenn R.
A causal examination of the effects of confounding factors on multimetric indices
The development of multimetric indices (MMIs) as a means of providing integrative measures of ecosystem condition is becoming widespread. An increasingly recognized problem for the interpretability of MMIs is controlling for the potentially confounding influences of environmental covariates. Most common approaches to handling covariates are based...Schoolmaster, Donald R.; Grace, James B.; Schweiger, E. William; Mitchell, Brian R.; Guntenspergen, Glenn R.
A general theory of multimetric indices and their properties
1. Stewardship of biological and ecological resources requires the ability to make integrative assessments of ecological integrity. One of the emerging methods for making such integrative assessments is multimetric indices (MMIs). These indices synthesize data, often from multiple levels of biological organization, with the goal of deriving a...Schoolmaster, Donald R.; Grace, James B.; Schweiger, E. William
Guidelines for a graph-theoretic implementation of structural equation modeling
Structural equation modeling (SEM) is increasingly being chosen by researchers as a framework for gaining scientific insights from the quantitative analyses of data. New ideas and methods emerging from the study of causality, influences from the field of graphical modeling, and advances in statistics are expanding the rigor, capability, and even...Grace, James B.; Schoolmaster, Donald R.; Guntenspergen, Glenn R.; Little, Amanda M.; Mitchell, Brian R.; Miller, Kathryn M.; Schweiger, E. William
Lack of Major Hurricanes Since 2008 Is Likely the Main Reason