Long Term Research in Environmental Biology (LTREB): Stream ecosystem structure and function within a maturing deciduous forest

Project Background

©2003 Stroud Water Research Center

The Stroud Water Research Center and its 800 ha, 3rd-order drainage basin was designated an Experimental Ecological Reserve in 1981 by the National Science Foundation (NSF). This designation, based upon the criteria of site quality, research activities, logistics and financial support, recognized that this field research facility was dedicated to long-term experimental research on an ecosystem this is an outstanding representative of its type. The East Branch of White Clay Creek is classified by the Commonwealth of Pennsylvania as an Exceptional Value stream and watershed. This the highest classification given and affords the watershed special protection against environmental disturbance of anthropogenic origin.

In 1998, the White Clay Creek experimental watershed, extending from the Stroud Water Research Center north to the headwaters, was designated as a site for long-term research in environmental biology (LTREB). The National Science Foundation LTREB grant to Center scientists recognizes that many important questions in ecology require the acquisition of long time series of data. NSF funds are being use to help maintain an on-going long-term research project examining stream and watershed characteristics associated with a riparian zone restoration/reforestation.

The White Clay Creek watershed, like most of the Eastern North American landscape, experienced dramatic anthropogenic disturbances over a relatively short time period (300 years). These are characterized by deforestation for lumber, charcoal, and agriculture, and more recently the broad scale creation of impervious surfaces, introduction of pesticides, increased use of fertilizers, and atmospheric deposition of nitrogen from the combustion of fossil fuels. These landscape and landuse changes have generated conditions that stress stream ecosystems, however, little is known about how streams in the Piedmont physiographic province have responded to these stresses. Even less is known about how streams respond as the disturbed landscapes recover. In this LTREB project, the over arching goals involve discerning the time period, most salient features, and final condition of a recovered state. LTREB funding is being used to: (1) maintain existing watershed installations to continue an on-going acquisition of long-term data on White Clay Creek, (2) address the data management needs of the long-term project, including making the data available to the research community, and (3) testing hypotheses concerning long-term variations in stream ecosystem structure and function under stable and/or recovering conditions.

Site History

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©2003 Stroud Water Research Center

When the Stroud Water Research Center was established in 1967, the agriculturally dominated watershed contained an upstream riparian forest of 60 to 100 year old trees and downstream meadows subject to cattle grazing. Initially, several long-term sampling reaches on the White Clay Creek were selected, including woodland and meadow reaches. When cattle were removed from the meadow reach adjacent to the laboratory, the riparian zone became colonized by multiflora rose (Rosa multiflora (Thunb)). Over a 23-year period the multiflora rose grew to border the stream in a swath that was 3 meters tall and 5 meters wide. In 1989, the Center began a riparian zone restoration and reforestation project with the goal of reestablishing a contiguous deciduous forest extending through the meadow reach upstream to headwater spring seeps 3 km away. Multiflora rose plants were uprooted and tree seedlings of native species were planted. Between 1988 and 1994, five lateral transects from the uplands to the stream were instrumented with wells, lysimeters, and in-stream piezometers. In 1997, the reforestation project was extended into a meadow downstream of the laboratory.

Existing Data Sets for White Clay Creek

Data for White Clay Creek are separated into categories of physical, chemical, and biological parameters and provide information on the site, period of collection, and frequency of collection (Table 1). Included in these categories are: (1) variables such as stream discharge, air and water temperature, rainfall, water chemistry, and aquatic insect emergence that have been collected continuously or regularly for more than 30 years; and (2) other variables such as channel geomorphology, organic matter inputs and exports, and various aspects of the structure and function of stream biota that have been examined intermittently.

Table 1: White Clay Creek Data Sets
Parameters with available datasets are linked.

A major emphasis of the LTREB program during its initial 5-year funding period has been data management and accessibility. We have successfully installed a new computing system at the Stroud Water Research Center based on the Microsoft operating system, and have transferred all electronic data sets to the new system. This has enabled us to begin uploading data for the White Clay Creek to this web site for public access. The initial data sets include 30 years of stream discharge, and water chemistry, and 5 years precipitation. Discharge is presented as daily maximum, precipitation is daily total, and water chemistry is presented as the concentration based on a periodic grab sample. All data are separated into annual reports and presented in a tab-delimited format. At this time, we expect to continue to make annual updates to the data sets on this web site, and to gradually add more of the data sets listed in Table 1 as time allows.