Long-Term Research in Environmental Biology: White Clay Creek, Pennsylvania

325 292 Stroud Water Research Center

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 and 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 is 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 NSF LTREB grant to Stroud Center scientists recognizes that many important questions in ecology require the acquisition of long time series of data. NSF funds are being used to help maintain an on-going long-term research project examining stream and watershed characteristics associated with a riparian zone restoration/reforestation.

In this LTREB project, the overarching goals involve discerning the time period required for recovery and the 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.

Project Site

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.

When 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.


The tables below list our long-term datasets for White Clay Creek, a subset of which are available for download on HydroShare. If you have trouble accessing the data, please email

Physical Data

Discharge is presented as daily maximum and precipitation as daily total.

ParameterSitePeriod of RecordFrequency
DischargeWatershed boundary1969-presentContinuous
TemperatureMeadow, woodland, & springs1969-presentContinuous
Channel GeomorphologyWoodland, meadow, tributaries1972-presentPeriodic
Solar RadiationMeadow1969-presentContinuous

Chemistry Data

Water chemistry is presented as the concentration based on a periodic grab sample.

ParameterSitePeriod of RecordFrequency
Nutrients: NO3, NO2, NH3, PO4Woodland1969-presentWeekly 1969-1995;monthly 1996 present
Meadow1996-presentStorms once/season
Springs & tributaries1969-1989Once to several times annually
Wells & lysimeters1994-1997Every other month, 1994-1997; 1998-present periodic
Nutrients: TKN, TPWoodland1996-presentMonthly
Cations: Ca, K, Mg, a, Zn, Cu, Mn, FeWoodland1969-presentWeekly 1969-1995; monthly 1996-present
Meadow1996-presentStorms once/season
Anions: SO4, ClWoodland1969-presentWeekly 1969-1995; monthly 1996-present
Meadow1996-presentStorms once/season
pH, alkalinityWoodland1969-presentWeekly 1969-1995; monthly 1996-present
ConductivityMeadow1994-presentDaily & each storm
Wells & lysimeters1994-1997
Every other month
Dissolved Organic CarbonMeadow1972-1975Weekly to monthly & seasonal storms
1978-1994Daily to weekly & seasonal storms
1995-presentDaily & all storms
Wells & lysimeters1988-1997
Weekly to every other month
Tributaries & springs1978-presentPeriodic
Classes of Organic Compounds
(lipids, carbohydrates, phenolics, amino
Meadow, tributaries & springs1972-presentPeriodic
Amino acid moleculesMeadow1993-presentSeasonal storms
Carbohydrate moleculesMeadow, wells, lysimeters, & springs1994-1996



Weekly & seasonal storms



Humic substancesMeadow, wells, lysimeters1993-1997Monthly
Humic-Bound Lignin PhenolsMeadow, woodland, wells, & lysimeters1993-1997Periodic
Biodegradable DOCMeadow1992-presentWeekly
Wells & lysimeters1994-presentPeriodic
PesticidesMeadow, woodland & tributaries1993-1997Periodic
Meadow1995-presentAll storms

Biological Data

ParameterSitePeriod of RecordFrequency
Suspended chlorophyllWoodland2001-2004
Benthic Organic MatterWoodland1976, 1997Seasonal
Leaf Litter InputsWoodland1973-1974Weekly
Woodland & meadow1991-2000
Weekly to monthly
Weekly to monthly
Woody DebrisWoodland & meadow1991Late Autumn
Algal BiomassWoodland & meadow1973-1975
Daily to weekly
Community Metabolism
(GPP, Respiration, Net Daily Metabolism)
Woodland & meadow1971-1975
Daily to weekly
Algal Community CompositionWoodland1969-1971Weekly to monthly
Bacterial ProductivityMeadow1980-81;Seasonally
1985-86; 1989Seasonally
Bacterial DensitiesMeadow1980-81; 1985-86; 1989; 1999-presentSeasonally
Bacterial Community CompositionWoodland & meadow1999-presentPeriodic
Protozoan Community CompositionWoodland1969-1970Weekly to monthly
Protozoan DensitiesMeadow & tributary1983-1985Monthly
Protozoan BacterivoryMeadow1984-1985Seasonally
Meiofauna Densities & Ingestion of MicrobesMeadow1993-1995Seasonally
Insect Species Richness, Density, BiomassWoodland1969-72; 1975-76;
1983; 1997-1998; 2003-2004
Monthly to bi-monthly
Meadow1991-1996Late Winter
Meadow & woodland1997-presentLate Winter
Insect EmergenceMeadow & woodland1970-presentWeekly
Insect Genetic StructureWoodland & meadow1983-1987, 2002Periodic
Insect Size and/or Fecundity (selected species)Woodland & meadow1969-1988
Fish Community CompositionWoodland & tributary1972-1973, 1989, 1995, 1997Periodic


This project was initiated with support from the National Science Foundation. Our donors and a suite of projects within the experimental area allow this critical long-term research to continue today.


Spatial scale impacts microbial community composition and distribution within and across stream ecosystems in North and Central America

Bier, R.L., J.J. Mosher, L.A. Kaplan, and J. Kan. 2023. Environmental Microbiology 25(10): 1860–1874.

A variable source area for groundwater evapotranspiration: impacts on modeling stream flow

Tsang, Y.P., G. Hornberger, L.A. KaplanJ.D. Newbold, and A.K. Aufdenkampe. 2014. Hydrological Processes 28(4):2439–2450.

Measuring heterotrophic respiration rates of suspended particulate organic carbon from stream ecosystems

Richardson, D.C., J.D. Newbold, A.K. Aufdenkampe, P.G. Taylor, L.A. Kaplan. 2013. Limnology and Oceanography Methods 11:247–261.

Estimation of dissolved organic carbon contribution from hillslope soils to a headwater stream

Mei, Y., G.M. Hornberger, L.A. Kaplan, J.D. Newbold, and A.K. Aufdenkampe. 2012. Water Resources Research 48(9):W09514.

Biological lability of streamwater fluorescent dissolved organic matter

Cory, R.M., and L.A. Kaplan. 2012. Limnology and Oceanography 57(5):1347–1360.

The impact of terrestrial dissolved organic carbon on stream ecosystems through an investigation of hydrologic sources

McLaughlin, Christine. 2012. Ph.D. dissertation. University of Pennsylvania, Philadelphia. Adviser: L.A. Kaplan.