John Wesley Powell Center for Analysis and Synthesis

Land Resources

Powell Center working groups rarely are just one USGS Mission Area and are sorted into these areas by the groups themselves. Projects may be relevant to additional areas.

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Filter Total Items: 26
Date published: October 22, 2013
Status: Active

Advancing understanding of ecosystem responses to climate change with warming experiments: what we have learned and what is unknown?

Advancing our mechanistic understanding of ecosystem responses to climate change is critical to improve ecological theories, develop predictive models to simulate ecosystem processes, and inform sound policies to manage ecosystems and human activities. Manipulation of temperature in the field, or the “ecosystem warming experiment,” has proved to be a powerful tool to understand ecosystem...

Date published: October 21, 2013
Status: Active

Transport of dissolved organic matter by river networks from mountains to the sea: a re-examination of the role of flow across temporal and spatial scales

The transport of dissolved organic matter (DOM) by rivers is an important component of the global carbon cycle, affects ecosystems and water quality, and reflects biogeochemical and hydrological processes in watersheds. Understanding the fundamental relationships between discharge and DOM concentration and composition reveals important information about watershed flow paths, soil flushing,...

Date published: October 21, 2013
Status: Active

Modeling species response to environmental change: development of integrated, scalable Bayesian models of population persistence

Estimating species response to environmental change is a key challenge for ecologists and a core mission of the USGS. Effective forecasting of species response requires models that are detailed enough to capture critical processes and at the same time general enough to allow broad application. This tradeoff is difficult to reconcile with most existing methods. We propose to extend and combine...

Date published: October 18, 2013
Status: Active

Evidence for shifts in plant species diversity along N deposition gradients: a first synthesis for the United States

The impacts of nitrogen (N) deposition on plant diversity loss have been well documented across N deposition gradients in Europe, but much less so in the U.S. Published N fertilizer studies suggest losses will occur in the US, but many of these were done at levels of N input that were higher than modeled and measured N deposition, and higher than presumed N critical loads. The recent...

Contacts: Matthew Brooks
Date published: September 24, 2013
Status: Active

Understanding and managing for resilience in the face of global change

Resilience science provides a conceptual framework and methodology for quantitatively assessing the ability of a system to remain in a particular state. Probable non-linear ecological responses to global change, including climate change, require a clear framework for understanding and managing resilience. However, much of the resilience research to date has been qualitative in nature, and...

Date published: September 23, 2013
Status: Active

PlioMIP (Pliocene Model Intercomparison Project) Strategy, Communications and Synthesis for the IPCC Fifth Assessment Report (IPCC AR5)

USGS PRISM (Pliocene Research, Interpretation and Synoptic Mapping) Project global data sets of Pliocene conditions, which form the most comprehensive global reconstruction for any warm period prior to the recent past, are used to drive numerical climate model simulations designed to explore the impact of climate forcings and feedbacks during the Pliocene. The Pliocene world provides an...

Date published: September 20, 2013
Status: Active

Animal Migration and Spatial Subsidies: Establishing a Framework for Conservation Markets

Migratory species may provide more ecosystem goods and services to humans in certain parts of their range than others. These areas may or may not coincide with the locations of habitat on which the species is most dependent for its continued population viability. This situation can present significant policy challenges, as locations that most support a given species may be in effect...

Date published: September 19, 2013
Status: Active

Characterizing a link in the terrestrial carbon cycle: a global overview of individual tree mass growth

Forests sequester the majority of the terrestrial biosphere’s carbon and are key components of the global carbon cycle, potentially contributing substantial feedbacks to ongoing climatic changes. It is therefore remarkable that no consensus yet exists about the fundamental nature of tree mass growth (and thus carbon sequestration rate). Specifically, does tree mass growth rate increase,...

Date published: August 6, 2012
Status: Active

Next Generation of Ecological Indicators: Defining Which Microbial Properties Matter Most to Ecosystem Function and How to Measure Them

While it is widely recognized that microorganisms are intimately linked with every biogeochemical cycle in all ecosystems, it is not clear how and when microbial dynamics constrain ecosystem processes. As a result, it is know clear how to apply the value of increasingly detailed characterization of microbial properties to our understanding of ecosystem ecology. Several recent papers have...

Date published: June 7, 2012
Status: Active

Climate change and ecohydrology in temperate dryland ecosystems: a global assessment

Water cycling and availability exert dominant control over ecological processes and the sustainability of ecosystem services in water - limited ecosystems. Consequently, dryland ecosystems have the potential to be dramatically impacted by hydrologic alterations emerging from global change, notably increasing temperature and altered precipitation patterns. In addition, the possibility of...

Date published: June 1, 2012
Status: Active

System analysis of land use and climate effects on ecosystem services affecting C and N exchanges with the atmosphere and water cycles

Current land use practices have affected ecosystem structure and processes in ways that have degraded delivery of key ecosystem services controlling exchanges of carbon and nitrogen with the atmosphere and surface and groundwater systems. These impacts are observed in the emissions of greenhouse gases (GHG) and N pollution in our nation’s water systems and coastal areas. Improvements in...

Date published: April 2, 2012
Status: Active

Global Croplands and Their Water Use for Food Security in the Twenty-first Century

Global climate change is putting unprecedented pressure on global croplands and their water use, vital for ensuring future food security for the world's rapidly expanding human population. The end of the green green revolution (productivity per unit of land) era has meant declining global per capita agricultural production requiring immediate policy responses to safeguard food security amidst...