This large project is led by the Pacific Northwest National Laboratory in collaboration with multiple partners, including the Smithsonian Environmental Research Center (SERC) and Argonne National Lab. The COMPASS - FME project aims to understand the coupled interactions of plants, microbes, soils/sediments, and hydrology within coastal systems to inform multi- scale, integrated models from reaction scales to the coastal terrestrial-aquatic interface (TAI). The projectís research emphasis is primarily on terrestrial and wetland processes that are influenced by coastal waters, such as the fluxes and transformations of carbon, nutrients, and redox elements through these systems. This project includes several national labs, and research institutions in the W. Basin of Lake Erie and Chesapeake Bay
The project comprises two parts: a field study and a coastal modeling study. COMPASS-FME: Field, Measurements, and Experiments, which focuses on field studies and associated process and ecosystem modeling of two coastal interfaces. COMPASS-GLM: Great Lakes Modeling focuses on modeling and analysis of coastal systems in the Great Lakes Region.
Dr. Weintraub is a co-Investigator on COMPASS-FME. COMPASS-FME seeks to advance a scalable, predictive understanding of the fundamental biogeochemical processes, ecological structure, and ecosystem dynamics that distinguish coastal terrestrial-aquatic interfaces (TAIs) from the purely terrestrial or aquatic systems to which they are coupled. To achieve the COMPASS vision, FME will focus on overarching long-term science questions: What fundamental mechanisms control the structure, function, and evolution of coastal TAIs? How do these fundamental mechanisms interact across spatial scales, and what interactions are most important to improving predictive models? The two-year COMPASS-FME pilot study aims to develop predictive understanding of the causes, mechanisms, and consequences of the shift between aerobic and anaerobic conditions at both saltwater and freshwater TAIs.
Biological and geochemical controls on phosphorus bioavailability in arctic tundra
National Science Foundation funded this three-PI/three institution
collaborative project in August 2019. Research and sample collection
began in Summer 2021.
Phosphorus (P) is a nutrient essential for life but its supply in the
environment is often limited, resulting in P limitation to plant growth
and/or decomposition in some environments. Plants and microorganisms
take up P as dissolved phosphate in soil water. Phosphate is also
removed from solution by binding with soil minerals. In particular,
iron minerals strongly bind phosphate and may regulate its availability
to plants and microorganisms. This project will investigate how
geochemical and biological systems “compete” for phosphate in arctic
tundra soils near Toolik Field Station, Alaska, where soil warming and
permafrost thaw are altering carbon and water budgets, which in turn
affects soil moisture and nutrient availability. This research is
broadly important to understanding how soil properties (e.g., soil
saturation and pH) affect this competition for phosphate and
consequently influence plant growth and the ability of arctic
ecosystems to serve as future carbon sources or sinks. The implications
of this work extend beyond arctic systems and will increase the
fundamental understanding of soil P availability.
Winter snow depth as a driver of microbial activity, nutrient cycling, tree growth and treeline advance in the Arctic
The National Science Foundation funded this three-PI/two-institution collaborative project in 2015. The field experiment was setup in September 2016, and research will continue through August 2021. The position of the Arctic treeline is an important regulator of surface energy budgets, carbon cycling and subsistence resources in high latitude environments. It has long been thought that temperature exerts a direct control on the growth of treeline trees and the position of the treeline. However, our recent work in the Arctic with white spruce suggests that indirect effects of temperature on soil nutrient availability may be of equal or greater importance. These results highlight the importance of winter snow depth as a driver of tree growth. If our hypotheses are confirmed by our experimental manipulations, our findings will alter our predictions of where and when treelines may advance. Cold soils at the treeline, particularly during winter, may limit microbial activity and nutrient availability to the point where trees are barely able to survive and grow.
Measurements made during winter have revealed that Arctic forests
maintain snowpacks that are much deeper than observed at treeline.
Trees are thought to trap snow and lead to a deeper snowpack,
insulating the soil from cold air and allowing for greater overwinter
microbial activity and greater nutrient mineralization. Indeed, we
found a strong positive correlation between white spruce growth and
winter snow depth. We are now conducting a field experiment to isolate
the mechanisms underlying this correlation by using snowfences to
manipulate winter snow depth and fertilizer to increase soil nutrient
availability at three treelines that differ in soil moisture. To
provide a test of the importance of temperature as a direct control
treeline tree growth, we are experimentally warming tree shoots. We
predict that both experimental snow and nutrient additions
will lead to
large increases in microbial activity, photosynthesis, tree growth,
seed production, seedling establishment and recruitment
of new trees. We expect to observe
the greatest positive responses
where soils are wet and cold. Meanwhile, we predict that
will lead to negligible changes in growth. This research will elucidate
the relationship between snow depth and soil nutrient availability, and
determine the relative importance of nutrient and temperature
limitations at treeline to white spruce—a dominant member of the boreal
forest and the northernmost tree species in North America.
Microbial control of litter decay
National Science Foundation funded this five-PI/four institution
collaborative project (Weintraub lead PI & project director) in
September 2009. That grant has ended, but this line of research
continues in my lab, including a collaboration with the Pacific
Northwest National Lab's Environmental Molecular Sciences Laboratory.
far, >15 publications and numerous training opportunities for
have resulted from the Toledo component of this ongoing
There is growing interest in understanding the conditions under which
soils gain or lose C, because soils actually contain more C than the
atmosphere and could play either a mitigating or exacerbating role in
global warming. Surprisingly, the microbial interactions with plant
litter chemistry and nutrient availability controlling decomposition
and soil C sequestration are not well understood,
because of surprising gaps in our understanding of the mechanisms
controlling decomposition. The goal of this research is to define these
relationships with integrated field, laboratory, and modeling studies
of the biochemical mechanisms driving interactions between soil C
sequestration, plant litter chemistry, and microbial community
composition and activity during decomposition.
We are investigating the functional links between decomposer
microorganisms, litter chemistry, and temperature using experiments
manipulate C and temperature over the course of
litter decomposition. Molecular studies are
currently under way to further determine the community composition of
active microorganisms capable of metabolizing specific chemical
components of plant litter. Our next goal is to determine how
communities and activities of soil
organisms, microbial enzyme production, and the efficiency of enzymatic
degradation of litter substrates are affected by temperature increases,
particularly at low temperatures, when decomposition is inhibited. This
research provides mechanistic insight into the impacts on plant
litter decomposition from climate change.
Additionally, the outreach activities from this project included
developing an the online Interactive Model Of Leaf Decomposition
Targeting grades 9-12, IMOLD starts with professionally animated
lessons on the C cycle, litter decomposition, and microbes. Users are
then directed to an interactive decomposition model allowing them to
decompose different litters in the same environment, or the same litter
in different environments. Lastly, IMOLD includes lab and classroom
lesson plans developed by teachers. This educational resource is
already being used in high school classrooms throughout the US.
past research projects, please click here.