Citation:

TALLENT-HALSELL, N. G. EXPOSURE OF RIPARIAN ECOSYSTEMS TO NON-INDIGENOUS PLANT SPECIES: A CONCEPTUAL RISK ASSESSMENT MODEL. Presented at International Society for Exposure Analysis Conference, Durham, NC, October 14, 2007.

Impact/Purpose:

The primary objectives of this research are to:

Develop methodologies so that landscape indicator values generated from different sensors on different dates (but in the same areas) are comparable; differences in metric values result from landscape changes and not differences in the sensors;

Quantify relationships between landscape metrics generated from wall-to-wall spatial data and (1) specific parameters related to water resource conditions in different environmental settings across the US, including but not limited to nutrients, sediment, and benthic communities, and (2) multi-species habitat suitability;

Develop and validate multivariate models based on quantification studies;

Develop GIS/model assessment protocols and tools to characterize risk of nutrient and sediment TMDL exceedence;

Complete an initial draft (potentially web based) of a national landscape condition assessment.

This research directly supports long-term goals established in ORDs multiyear plans related to GPRA Goal 2 (Water) and GPRA Goal 4 (Healthy Communities and Ecosystems), although funding for this task comes from Goal 4. Relative to the GRPA Goal 2 multiyear plan, this research is intended to "provide tools to assess and diagnose impairment in aquatic systems and the sources of associated stressors." Relative to the Goal 4 Multiyear Plan this research is intended to (1) provide states and tribes with an ability to assess the condition of waterbodies in a scientifically defensible and representative way, while allowing for aggregation and assessment of trends at multiple scales, (2) assist Federal, State and Local managers in diagnosing the probable cause and forecasting future conditions in a scientifically defensible manner to protect and restore ecosystems, and (3) provide Federal, State and Local managers with a scientifically defensible way to assess current and future ecological conditions, and probable causes of impairments, and a way to evaluate alternative future management scenarios.

Description:

Biological invasions are one of the foremost threats to the integrity of riparian

ecosystems worldwide, but little is known regarding the long-term invasion dynamics of

non-indigenous plant species (NIPS) along rivers. Riparian ecosystems are of great

importance because they maintain the physical and biochemical integrity of the landwater

interface within watersheds. Indigenous plants that occur along rivers provide

channel stabilization, buffer nutrient and contaminant inputs, and provide unique shelter,

forage, and breeding habitat for wildlife including birds, mammals and fish. The

indigenous plant species of riparian ecosystems have evolved under conditions specific to

transverse and longitudinal extent of the river thus are generally tolerant of the typical

and extreme conditions (i.e., drought, flooding, temperature, pests and diseases) inherent

to the watershed. Natural- and human-caused disturbance such as dams, channel

alterations, and urbanization alter energy and material flow into riverine ecosystems

exposing the riparian corridor to NIPS. However, biotic invasion is possible only when a

vulnerable habitat meets with a species whose traits allow establishment, growth, and

spread. We propose using the risk assessment framework to assess the risk of NIPS on

riparian ecosystems. We will present our conceptual Risk Assessment Model to assess

the exposure of riparian ecosystems to non-indigenous plant species and invite discussion

of this topic from the Exposure Sciences community. Our conceptual model uses a site

and species specific case study (i.e., working with the Jamestown - S'Klallam tribe in the

Dungeness River watershed in northwestern Washington) for problem formation,

analyses, risk characterization and risk management. This process has revealed

information gaps, exposure research needs such as how to characterize the vulnerability

of riparian habitats to NIPS through mapping and identifying specific invasive species

hazards. In addition we present an assessment of the potential costs to native species and

ecosystem components and processes critical to the risk assessment process.

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