The Long-Term
Vegetation (LTV) Transects and associated permanent
vegetation plots (see map below) were established on what is
now the Idaho National Laboratory (INL) Site, in 1950 for
the purpose of assessing the impacts of nuclear energy
research and production on surrounding ecosystems.
Vegetation abundance data were first collected in 1950 for
inclusion in an ecological characterization of the Site.
Samples of plant and animal tissues were also collected from
these plots and analyzed for radionuclide concentrations on
an annual basis for several years. The effort to collect
tissue samples was eventually discontinued because the
effects of fallout from nuclear reactors were determined to
be negligible, at least
in terms of radionuclide concentrations in the environment.
However, collection of vegetation abundance data has
continued on a regular basis for nearly sixty years.
The data generated from the LTV Transects comprises one of
the oldest, largest, and most comprehensive vegetation data
sets for sagebrush steppe ecosystems in North America. Since
their establishment, the LTV Transects have been used
extensively for various tasks to support the INL Site
mission and have been the basis for major milestones in
understanding practical and theoretical ecology of sagebrush
steppe vegetation dynamics. Applications of the LTV data
include:
Plant
community classification and mapping,
Assessing
the effects of drought and livestock grazing,
Understanding fire history and recovery,
Characterizing species invasion patterns,
Testing
theories of vegetation succession and change,
As a basis
for habitat suitability modeling for sensitive species,
Supporting
NEPA processes,
Making
appropriate land management recommendations, and
Developing
specific revegetation recommendations.
In addition to the functions listed above, the LTV data set
is still used to assess the impacts of energy development on
the environment, as was intended in 1950. However, impacts
beyond radioactive fallout, such as exotic species invasion,
habitat fragmentation, and global climate change are of
current interest.
The eleventh
LTV data set was collected during the summer of 2006. Two
tasks were undertaken in association with the 2006 data
collection. The first task involves a major effort in
updating and describing the data archives. The second
includes summarization and analysis of the 2006 and all
previously collected abundance data.
The last
attempt at organizing and archiving the LTV data was
completed in the early 1980s. Although care has been taken
to format and store data collected since 1983 in a manner
consistent with the protocol established at that time, the
data archives have become outdated. The software available
for archiving and processing data has improved substantially
over the past 25 years, necessitating an update of the LTV
data files. A considerable amount of the work associated
with entry and summary of the 2006 data included designing
and populating a relational database for all of the LTV data
from 1950-2006. Additionally, the specific sampling
protocol will be documented and a thorough history of the
LTV will be included as part of the reporting effort.
Analyses on
the 2006 and previous data can be summarized under two focus
areas. The first includes characterizing general plant
abundance and community composition trends, similar to
analyses described in previous LTV reports. The second
group of analyses will concentrate on characterizing
patterns of exotic species invasion and determining the
effects of invasion on vegetation cover and composition of
native plant communities subsequent to invasion.
Accomplishments through 2009 include collection of the 2006
data and completion of quality assurance/quality control
procedures on that data set. The 2006 data were also
summarized, formatted, and imported into a comprehensive
relational database. The database was thoroughly documented
and verification/validation routines were performed on the
data contained therein. Verification and validation
processes were used to ensure the integrity and
completeness, as well as to resolve issues associated with
taxonomic classifications and scaling, of the historical
data set. A specific protocol for use in collecting LTV
data was designed and drafted in association with the 2006
data collection effort.
Analyses
summarizing INL Site vegetation trends over the past 56
years were completed in 2009. Changes in abundance and
composition through time were addressed by comparing
absolute cover at the species level over the past decade and
changes in the total cover of functional groups and key
shrub species over the entire 56-year data set. Patterns of
exotic species invasion were investigated using a mapping
exercise to identify changes in the presence and abundance
of cheatgrass and other non-native annual species across the
LTV plots through time. Results of the mapping exercise
were compared to changes in mean density and frequency of
the target species or group of species between sample
periods in an effort to characterize general
spatial/temporal patterns of invasion on the INL Site.
Five chapters
were outlined for inclusion in the final report, and drafts
of each were completed by spring 2009. The five chapters
include: (1) a brief introduction, (2) a comprehensive
history of the LTV permanent plots and associated vegetation
studies, (3) a detailed protocol to be used to guide data
collection efforts and maintain continuity in future data
collection efforts, (4) a thorough documentation of the
updated database structure, and (5) results of analyses
addressing long-term plant community change and invasive
species patterns. The entire report was submitted for
review in 2009.
The database
includes seven raw data and metadata tables. The general
structure of the database is depicted in Figure 13. The
metadata tables include information about plant species on
the INL Site, information about each of the permanent plots
on the LTV Transects, and information about the sampling
history on the LTV plots. Of the four data tables contained
within the database, three tables are comprised of
vegetation abundance data and one includes information about
plot photos. The abundance data tables contain
density/frequency data, cover data estimated using line
interception, and cover data estimated using point
interception. The photograph specifications data table was
designed to consolidate data associated with photos taken
during LTV data collection efforts including photo dates,
exposure, aperture, camera angle, etc. The photo data table
was designed such that the record of each photo can include
a hyperlink to a digital copy of that photo. Accordingly,
all of the historical photos were digitized as part of the
update to the LTV archive. The photograph specification
data table was not populated as a part of the current
effort; however, the historical photos have been properly
archived in a digital format to streamline integration as
part of future efforts.
Results from
analyses on trends in species composition and abundance
indicate that although the cover of major functional groups
remains relatively stable through time, the cover of species
within those groups can vary dramatically over just a
decade. Species composition, it terms of absolute cover,
from the 2006 sampling effort are shown in Table 8. Cover
of big sagebrush (Artemisia tridentata) has continued
to decline through the 2006 sampling effort, and the cover
of crested wheatgrass (Agropyron spp.) is increasing
rapidly, albeit at a local scale. Results from the analyses
on trends of invasive species indicate that the spatial
distribution of cheatgrass has increased over the study
period; however, the mean density and frequency have not
increased as predictably as expected. The abundance and
distribution of other non-native annuals, specifically,
desert madwort (Alyssum desertorum) is increasing far
more rapidly (Forman et al. 2010).
The LTV report will be
finalized and publicly available in calendar year 2010. Two
peer-reviewed publications containing results from the
current LTV data set will also be prepared and submitted as
time and funding allow.
