\log
The initial iteration of the documentation section of this file was
created by Gina Adams in late December 1997. The documentation and
data sections of this file were provided by Gina Adams via floppy
diskette on 23 December 1997. Minor editorial revisions were made
by Mike Hartman, and the file was placed under sccs control on 17
April 2001.
\doc
TITLE. Effect of krummholz establishment on soil previously occupied by
tundra: carbon and nitrogen properties.
ABSTRACT. Previous work has shown that passage of Englemann spruce
(Picea Englemanii) and subalpine fir (Abies lasiocarpa) tree islands
across tundra lowers the soil carbon and nitrogen storage capacity of
the top 15cm of soil (A horizon) (Pauker and Seastedt 1996). This data
forms part of a study which seeks to further examine how changes in
carbon storage capacity are associated with changes in soil physical
properties. Soils were collected in 1994. We sought to determine
whether there were changes in natural abundance of C and N isotopes
associated with previously reported changes in C and N content. Any
such changes in natural abundance of C and N isotopes may indicate
differences in inputs to the ecosystem or differences in ecosystem
processes that may account for the differences in N and C content that
have been observed. In addition to measuring ratios of natural isotopes
of C and N, we also measured C and N contents to provide a comparison with
previous studies. In order to convert % N and C values to Kgs of N and C
per m2 we used bulk density values, meaned across sampling dates, that had
been previously measured for these sites (these raw data are available at:
http://culter.colorado.edu/exec/.extracttoolA?krmslblk.ts).
When N and C soil contents were considered on a percentage basis, levels
at windward sites were significantly lower than those of undisturbed tundra,
but levels directly beneath krummholsz were not significantly different
from tundra soils. Bulk density was significantly lower under krummholz
than other sites. Thus when N and C amounts were expressed on a volume
(Kg m2, to a depth of 15cm) , they were significantly lower in both
krummholz and windward sites than in undisturbed tundra. D13C values
of soils under krummholz were significantly less negative under krummholz
than from windward or undisturbed tundra sites. A less negative
d13C value is indicative of less discrimination and may be attributable
to either vegetation differences or differences in decomposition rates.
D13C signatures of krummholz and tundra vegetation were also examined
and are available at:
http://culter.colorado.edu/exec/.extracttoolA?krmslrts.ts
INVESTIGATOR. Tim Seastedt, INSTAAR, CB 450, University of Colorado,
Boulder, CO, 80309-0450, (303) 492-3302 or (303) 492-0434,
tims@culter.colorado.edu.
VARIABLES. soil N, soil C, soil C:N ratio, soil bulk density, soil d13C,
soil d15N.
KEYWORDS. tundra, krummholz, soil carbon and nitrogen content, soil bulk
density, natural isotopic abundance, d13C, d15N.
LOCATION. Study sites were randomly selected subalpine fir and
Engelmann spruce tree islands in dry meadows on Niwot Ridge. The study
area encompassed the north and south facing slopes of a saddle east of
the tundra lab on Niwot Ridge. The elevation of the study site was
approximately 3600 m. Samples and original data are stored in Research
Laboratory #1 (Room 178a) at INSTAAR.
TIMING. Samples were collected in the summers of 1994-1997.
CITATIONS. [1]Marr, J.W. 1977 The development and movement of tree
islands near the upper limit of tree growth in the Southern Rocky
Mountains. Ecology 58:1159-1164.
[2]Burns, S. 1980. Alpine soil distribution and development. Indian
Peaks, Colorado Front Range. PhD dissertation, University of Colorado,
Boulder. 360 pp.
[3]Thorn, C.E. 1982. Gopher Disturbance: Its variability by Braun-Blanquet
vegetation units in the Niwot ridge alpine tundra zone, Colorado Front Range,
USA. Arctic and Alpine Research 14:45-51.
[4]Holtmeier, F-K and Broll, G. 1992. The influence of tree islands
and microtopography on pedeological conditions in the forest-alpine
tundra ecotone on Niwot Ridge, Colorado Front Range, USA. Arctic and
Alpine Research 24: 216-228.
[5]Pauker, S. J and Seastedt, T.R. 1996. The effect of mobile tree islands
on soil carbon storage in tundra ecosystems. Ecology 77(8): 2563-2576.
[6]Seastedt, T.R. and Adams, G.A. 2001. Effects of mobile tree islands
on alpine tundra soils. Ecology 82:8-15.
COMMENTS. Data were provided by Gina Adams via floppy diskettes. Tree
island samples were collected in minimal snow cover soil described by
Burns (1980) as follows: The soil is composed of Pergelic Cryumbrept of
a loamy-skeletal, mixed type, probably eolian in origin with moderately
thick, fine-textured A horizons overlying a cambic B horizon. Where A
horizons are not thick enough to be classified as umbric epipedon, soil
is classified as Dystric Pergelic Cryochrept of a coarse-loamy, mixed
type. These latter characteristics described the soil on the windward
side of tree islands, which was confirmed by Holtmeier et. al. (1992).
Less than 15% rock cover occurs on the ground surface, although
extremely rocky areas found in this soil type are have been interpreted
to be edges of buried patterned ground, suggesting extensive permafrost
in the past. Vegetational communities dominating this dry meadow area
are primarily Association Selaginello-Kobresietum myosuroidis, and
Association Caricetum elynoidis with some areas of Acomastylis rossii
(Burns 1980). Pocket gopher (Thomomys talpoides) disturbance occurs
regularly in the Acomastylis (Thorn 1982), leaving esker-like mounds of
soil on the surface. Various forbs and willows (Salix brachycarpa) tend
to invade the wind-sheltered leeward side of tree islands, and are
eventually either killed by the advancing tree, or become mixed with
the branches of the island (Marr 1977).
The tree islands used for study were a random sample from a larger
group that met the following criteria: - they were large enough to
have affected the soil for many years (at least 5m long) - they were
not located on the most rocky soils (fell-field) - there was a patch of
undisturbed tundra (dry meadow, dominated by Kobresia mysuroides)
within 5m of the krummholz edge. Soil cores were taken to a depth of
15cm using 3.6 cm diameter PVC pipes. At each tree island, soils were
sampled, within the krummholz (at least 50cm inside the krummholz,
towards the windward end of the tree island (i.e. the location that had
been forested for the greatest length of time)), in the undisturbed
tundra (less than 5m upslope and downslope from the tree island). We
attempted to remove the litter and fragmented organic matter (O
horizon) of the tree island soils. No O horizon existed on tundra
soils. At each location two replicate cores were taken and composited.
The soils were air dried and then sieved through a 2 mm mesh. A
subsample of the soil was ground in a ball mill until it was an
extremely fine powder (about 5 days). Immediately prior to analysis of
% C and % N the soils were placed in an oven at 60C, to remove all
water. % C and % N were analyzed on the samples using a Leco-CHN
analyzer at NREL, CSU, Fort Collins. D15N and d13C were analyzed using
a VG-isochron mass spectrometer at NREl, CSU, Fort Collins.
Sample identification codes are comprised of 7 characters. The first
three characters denote the id of the tree island (T01 through T12).
The codes used to identify tree islands do not provide any other
information about the tree. The next three characters refer to the
location of the soil sample collected. W01 = windward location, <1m
from the tree island,. K01 = inside the krummholz and T01 = soil core
taken from adjacent, undisturbed tundra . The final (7th) character
provides information about the tree species. F = subalpine fir, S =
Engleman Spruce and X = no species information available.
\type
statistical
\header
COL1. label=date sample was collected (mm/dd/yy), type=string,
units=none, missing value indicator=, minimum=06/25/94,
maximum=07/15/94, precision=
COL2. label=sample identification code, type=string, units=none,
missing value indicator=, minimum=, maximum=, precision=
COL3. label=soil percent N, type=real, units=percent, missing value
indicator=, minimum=, maximum=, precision=
COL4. label=soil percent C, type=real, units=percent, missing value
indicator=, minimum=, maximum=, precision=
COL5. label=soil C:N ratio, type=real, units=none, missing value
indicator=, minimum=, maximum=, precision=
COL6. label=bulk density, type=real, units=g, missing value indicator=,
minimum=, maximum=, precision=
COL7. label=soil N, type=real, units=Kg m-2, missing value indicator=,
minimum=, maximum=, precision=
COL8. label=soil C, type=real, units=Kg m-2, missing value indicator=,
minimum=, maximum=, precision=
COL9. label=d15N, type=real, units=%o (parts per thousand), missing
value indicator=, minimum=, maximum=, precision=
COL10. label=d13C, type=real, units=%o (parts per thousand),
missing value indicator=, minimum=, maximum=, precision=
{*********************************************************************
If the data section below contains no data then you will need to
obtain permission from the investigator listed in the documentation
section of this file. If you have obtained permission or if the data
are already contained in this file, include the following
acknowledgment (in addition to an acknowledgment of the investigator)
in any published use of these data: "Logistical support
and/or data were provided by the Niwot Ridge Long-Term Ecological
Research project (NSF DEB 0423662) and the Mountain Research Station
(BIR 9115097)." Please send 4 reprints or high-quality copies of any
such publications to Todd Ackerman, NWT LTER data manager,
INSTAAR, CB 450, University of Colorado, Boulder, CO, 80309-0450.
The data contained in these files have many sources. Generally,
data collected prior to 1993 would have been subjected to quality
control standards imposed by the investigator. Data after 1992
were likely to have been manually entered and/or processed in the
NWT LTER central data management laboratory. Detailed information
on the quality control protocols and programs associated with any
data routed through the NWT LTER data management laboratory will
be supplied upon request. The user of these data should be aware
that, while efforts have been taken to ensure that these data are
of the highest quality, there is no guarantee of perfection for
the data contained herein and the possibility of errors exists.
If you encounter questionable data, please contact the NWT LTER
data manager (todda@culter.colorado.edu; (303) 492-4771) so that
the data can be corrected or qualified. Thus, these data should
be considered dynamic in that past data may be modified and future
data will be appended.
******************************************************************}
\data
06/25/94,T01T01X,0.581,7.872,13.54905,0.398896,0.347638,4.710167,24.7,1.26
06/25/94,T01K01X,1.387,21.32,15.3713,0.17804,0.370411,5.693705,24.13333,1.28
06/25/94,T01W01X,0.812,10.57,13.01724,0.334446,0.407355,5.302638,24.434,2.48
06/25/94,T02T01X,0.641,9.13,14.24337,0.493775,0.474764,6.762243,24.25,2.73
06/25/94,T02K01X,0.848,12.66,14.92925,0.402678,0.512207,7.646863,24.61,3.9
06/25/94,T02W01X,0.469,7.003,14.93177,0.398263,0.280178,4.18355,24.58,3.43
06/25/94,T03T01X,0.471,7.749,16.45223,0.446102,0.315171,5.185265,24.85,3.4
06/25/94,T03K01X,0.656,10.01,15.25915,0.313419,0.308404,4.705989,23.85,4.38
06/25/94,T03W01X,0.403,6.141,15.23821,0.633592,0.383006,5.836334,24.54,4.84
06/25/94,T04T01F,0.661,9.159,13.85628,0.48988,0.485716,6.730217,24.38,4.05
06/25/94,T04K01F,0.795,14.69,18.47799,0.342586,0.408533,7.548873,24.3,4.32
06/25/94,T04W01F,0.429,6.569,15.31235,0.528891,0.340341,5.211424,24.38,3.52
06/25/94,T05T01X,0.352,5.246,14.90341,0.496613,0.262211,3.907844,24.4,3.16
06/25/94,T05K01X,0.56,8.716,15.56429,0.452675,0.380247,5.91827,24.2,4.54
06/25/94,T05W01X,0.481,6.893,14.33056,0.435796,0.314427,4.505912,24.78,3.23
07/06/94,T06T01F,0.568,8.006,14.09507,0.451702,0.38485,5.424487,24.37,3.95
07/06/94,T06K01F,0.321,4.879,15.19938,0.228784,0.11016,1.674357,24.21,3.24
07/06/94,T06W01F,0.51,8.195,16.06863,0.526277,0.402602,6.469254,24.5,3.03
07/06/94,T07T01F,0.442,7.858,17.77828,0.491475,0.325848,5.793017,24.15,2.4
07/06/94,T07K01F,0.414,7.207,17.40821,0.285172,0.177092,3.082854,23.52,1.53
07/06/94,T07W01F,0.171,2.893,16.91813,0.400019,0.102605,1.735882,23.51,2.82
07/06/94,T08T01S,0.747,11.09,14.84605,0.476573,0.534,7.927793,23.95,3.39
07/06/94,T08K01S,0.438,7.397,16.88813,0.368638,0.242195,4.090226,23.7,3.92
07/06/94,T08W01S,0.195,3.073,15.75897,0.425162,0.12436,1.959782,23.44,3.27
07/06/94,T09T01F,0.26,4.334,16.66923,0.641862,0.250326,4.172744,24.1,3.48
07/06/94,T09K01F,0.374,6.685,17.87433,0.603503,0.338565,6.051631,23.25,3.24
07/06/94,T09W01F,0.149,2.592,17.39597,0.427916,0.095639,1.663736,23.7,3.12
07/06/94,T10T01F,0.429,6.544,15.25408,0.463121,0.298018,4.545995,23.93,5.99
07/06/94,T10K01F,0.356,5.287,14.85112,0.416988,0.222672,3.306926,23.83,3.92
07/06/94,T10W01F,0.356,6.229,17.49719,0.456272,0.243649,4.263174,24.51,2.32
07/06/94,T11T01S,0.641,10.44,16.28705,0.523482,0.503327,8.197721,24.72,4.32
07/06/94,T11K01S,0.488,8.156,16.71311,0.348578,0.255159,4.264503,23.81,4.79
07/06/94,T11W01S,0.547,8.252,15.08592,0.435829,0.357598,5.39469,24.52,4.81
07/15/94,T12T01X,0.598,8.132,13.59866,0.494842,0.443874,6.036087,24.81,5.51
07/15/94,T12K01X,0.433,6.698,15.46882,0.375499,0.243886,3.772635,24.02,3.29
07/15/94,T12W01X,0.431,6.352,14.73782,0.574288,0.371277,5.471812,24.3,4.66