**Fires and soil biogeochemistry:**

**Characterizing water quality impacts and predicting long-term trends
in ecosystem recovery**

A Proposal for USGS Geologic Science

Raymond F. Kokaly, USGS-Geology Discipline-Central Region, Crustal
Imaging & Characterization Team

**Statement of Problem**

Fire is a major component of forest and rangeland ecosystem dynamics in
the western United States. Warmer, drier winters have led to an increase
in tree mortality from insect damage, which, following decades of fire
suppression, has resulted in high-magnitude forest fires. Complexity
across a burned landscape, including variation in the severity of fire
and natural variations in vegetation, soils, and geology, complicates an
assessment of the short- and long-term consequences of fire for water
quality and vegetation recovery. As called for in recent scientific
publications, comprehensive studies of post-fire ecosystems, including
the physical, chemical and biological composition of soils, are needed
to model erosion, changes in water quality, and vegetation dynamics.
Uniquely, the USGS has broad and deep expertise in all science
disciplines for studying the complex interactions in ecosystems in order
to provide much needed information to land managers and local agencies
on expected impacts to water sources and long-term trends in soil
conditions and vegetation. Human populations are growing, expanding
communities in fire-prone areas, and becoming increasingly reliant on
water resources from wilderness areas; as a result, need for this
scientific understanding will increase in the future. As climate
changes, the role of fire in ecosystems may increase and more attention
may be brought to fire's importance in carbon and nitrogen cycles.

**Objectives:**

-   Establish framework understanding of how the interactions of fire
    severity, pre-fire vegetation cover and geologic substrate relate to
    post-fire soil condition (physical, chemical and biologic
    composition) and vegetation cover (including invasive plant
    species).

-   Model post-fire water and wind erosion of ash and soils, landslide
    potential, water quality, and vegetation mortality and recovery as a
    function of both pre-fire conditions and post-fire soils, surface
    cover, geologic substrate, surviving vegetation, topography and
    climate.

-   Monitor post-fire conditions with multispectral & hyperspectral
    remote sensing & landscape metrics.

-   Develop spatial models of potential post-fire water quality, soil
    condition, and vegetation dynamics.

**Work Strategy**

Expertise from all disciplines of the USGS is required to measure and
model these aspects of the ecosystem: burn severity, soil physical
properties, soil biogeochemistry (including organic carbon content,
nitrogen availability, nutrient pools, metals, trace elements, and
microbial composition), erosion, landslide potential, water quality,
vegetation cover, landscape metrics, and avian, terrestrial and aquatic
wildlife populations. In addition to field studies, remote sensing is
needed for expanded spatial characterization of soils and vegetation.
The proposed study area, the Rocky Mountain region, is a place where
many current and past USGS research projects related to fire science
have been conducted; in the area, human occupation is expanding into
adjacent wilderness. Historical satellite data over abundant past fires
can be used to evaluate the long-term trends in fire frequency, severity
and vegetation recovery, serving as a context for comprehensive field
and modeling studies of newly burned areas. The success of this research
effort will depend on building the existing capabilities of the USGS
geologic discipline to characterize soil components with detailed
laboratory and remote sensing methods, in addition to developing new
abilities in geomicrobiology and metagenomics to define
geologic-biological relationships and processes in soils.

**Relevance and Impact**

In relation to USGS science directions, the proposed science activities
will contribute directly to: (1) *Understanding Ecosystems & Predicting
Ecosystem Change*, and (2) *Quantifying Forecasting & Securing
Freshwater for America's Future*. Site specific results from the
research can be expected to benefit these science directions: (a) *The
Role of the Environment & Wildlife in Human Health*, and (b) *A Natural
Hazards, Risk, & Resilience Assessment Program*. Fire is strongly linked
to climate, thus, additional research can address *Climate Variability &
Change*.

**Partnerships**

Within the USGS, members of a previously funded venture capital project
and members of the fire science thrust are a natural nucleus for
establishing an integrated science plan. The wildland fire science
conference call, recently re-instituted by the USGS fire science
coordinator, demonstrates a broad grass-roots interest and commitment to
the topic by USGS scientists. These participants have conducted
interagency studies with Bureau of Land Management, US Fish and Wildlife
Service, US Forest Service, and National Park Service. The Joint Fire
Science Program, Bureau of Indian Affairs, University of Colorado, and
Colorado State University are likely partners.