PERMFILE65938

• Permit No: M2001001
• IBM Index Class Name: Permit File
• Doc Date: 5/23/2001
• Doc Name: NEWSPAPER CLIPPING
• Media Type: D
• Archive: No

1J ~Ya v1 LIlU tu: cV CNA tl! V LLV Y4aL
1
350 M. t_. Scott and otFrs
mCJI;/JKN'S
years; most were established prior m 1930, apparently
following large floods Q. Friedman unpublished data).
in 1990, a local sand and grave] mining firm pro-
posed m excavate sand from the active channel within a
portion oC the study reach. In cooperation with the
miner-, we designed a controlled, multiyear study of the
effects of water table decline on mature Populvs.
Methods
Field Methods
in October 1990, prior to deep mining of Coal
Creek. Four belt u-ansects 150 m wide were established
perpendicular to the channel 'Itvo transectt were lo-
sated within the proposed area of sand excavation, and
two additional ttarrsects were lorated upstream and down-
stream of the mining area m serve as controls (Figure 1).
The transecu were numbered sequentially from up-
strcam [o downstream and were extended amr>9s the entire
bonomland Because ofadjaccntlanddearing, the width of
transect 1 was reduced m 130 m. The belt tnnsects were
divided inm a series of discrete fluvial geomorphic
surfaces of relatively uniform elevation, hereafter re-
ferred to as surfaces. Elevations of the corners of a
surface were stuveyed using a rod and level Active channel
cross sections were resurveyed twice at each transecc
Three to fora groundwater wells were installed along
the center line of each [ransect using handdriven sand
points for shallow (<5 m) wells and atruck-mounted
drill for deeper wells. All wells were surveyed relative to
a common benchmark, and depth to the water table was
monitored in the wells from August 1990 to November
1994 using a steel tape. Water able depths were mea-
sured once or twice monthly during the growing season
(April-0ctober) and once per month for the remain-
der of the year. For each year, average growing season
depth to water was calculated at each surface by interpo-
lation between the two nearest wells.
Sand mining occurred in three stages; in October of
1990, approximately 0.5-1 m of sand was skimmed from
the surface of the channel at rransec[ 3 (Figure 7 ).This
activity continued slowly upstream over the next year to
a point between tnnsecls 1 and 2; no alluvial groundwa-
terwas exposed as a result of this activity. In December
1991, a shallow trench (<0.5 m) was dug within the
active channel from ttansect 2, downstream m a point
above tnnsect 4. From late June through August 1992,
deep mining of the channel at transect 3lorally lowered
the channel bed up to 2 m.
In June 1991. all [reel within [he bet[ trarrsects and
>2.54 cm diameter a[ breast heigh[ (dbh, 1.3 m) were
numbered with aluminum tags. Measurements of live
crown volume, stem growth, and mortality were initi-
•
aced in August. Stem diameters of all tagged, live trees
were measured in September 1991, October 1999, and
November 1994 by averaging three stem diameter
readings at permanently mazked positions 125, 130,
and 135 crrr above the ground. Live crown volume of
each tree was measured annually from 1991 through
1994 between August and September. This measure-
ment was a visual determination of the percentage of
potential crown volume occupied by live foliage and
branches. We report the average of crown volume
measurements from two independent observers. Survi-
vorship of all tagged trees was determined at the end of
each growing season by comparing the number of live
trees (live crown volume >0) in 1992, 1993, and 1994 to
the number of live trees in 1991. Dead trees were
excluded in calculating the average stem growth and
crown volume. in December 1994, armual branch
elongation for [he previous seven-year period was mea-
sured in all vansects on two randomly selected live trees
on each surface. Five live branches with a[ least seven
years of growth were collected from each selected tree,
and the increments between annual bud scale scars
were measured. Btattch elongaion values were normal-
ized by determining each year's percent deviation from
the premining avenge (1988-1991). The five deviation
values per year per tree were averaged to arrive at a
single avenge value per tree.
We performed a secondary set of measurements to
examine the effects of water table decline on leaf
xeromorphy. In September 1994, individual leaf area
(square centimeters) and~speci6c leaf mass (milligrams
per square centime[er) were measured on leaves from
24 trees. Across all transecrs, a total of eight trees were
randomly selected from each of three classes of water
table change: (I) +05 to -0.25 m; (2) -0.26 to -1.0
m; and (3) < -1.0 m. Fifty leaves were collected per
tree: 25 leaves from five branches removed from the
side of the crown and 25 leaves from five branrhes
removed from the mp of the crown. the leaves were
photocopied and areas were measured [wing a planim-
eter. Dry mass was determined by weighing leaves tha[
had dried in an oven at fi0°C for 72 h.
Statistical Methods
Our overall statistical analysis is presented in terms of
comparisons between tnnsects. Two of the tnnsects
(1 and 4) were relatively distant from the mining
opcntion and had little or no decline in water table
levels. We pooled surfaces from these [tansects in[o a
control group and used pairwise Ttests to compare with
the [Wined ttansects (2 and 3). In most rases sample
sizes and variances were unequal !n these cases we used
an approximate T statistic for unequal variances with
~j004