View
3
Download
0
Category
Preview:
Citation preview
HM
L
BLO
CK
1
H ML
BLO
CK
2
e L e vat i O n a B O v e g r O u n d wat e r
i r r i g at i O n
w e e d C O n t r O L
inti
alh
eig
ht(
cm)
510
1520
number of leaves0 2 4 6 8 10
0.5 0.6 0.7 0.8 0.9 0.95
0.99
02
46
810
number of leaves5
10
15
20
intial height (cm)
00.
20.
40.
60.
81
FRLA
surv
ival
pro
bab
ility
inti
alh
eig
ht(
cm)
1020
3040
5060
initial diameter (mm)5 10 15 20 25 30
0.50.60.70.8 0.90.95 0.99
510
1520
2530
initial diameter (mm)
10
20
30
40
50
60intial height (cm)
00.
20.
40.
60.
81
POFR
surv
ival
pro
bab
ility
number of leaves10 20 30 40
0.90.95
0.99
inti
alh
eig
ht
(cm
)10
2030
4050
60QULO
510
1520
2530 35 40
number of leaves
10
20
30
40
50
60
intial height (cm)
00.
20.
40.
60.
81
surv
ival
pro
bab
ility
ACNE
1
23
45
initial diameter (mm)
10
20
30
40
50
60
intial height (cm)
00.
20.
40.
60.
81
surv
ival
pro
bab
ility
initial diameter (mm)1 2 3 4 5
0.7 0.8 0.9 0.95 0.99
inti
alh
eig
ht
(cm
)10
2030
4050
60
inti
alh
eig
ht(
cm)
510
1520
number of leaves0 2 4 6 8 10
0.5 0.6 0.7 0.8 0.9 0.95
0.99
02
46
810
number of leaves5
10
15
20
intial height (cm)
00.
20.
40.
60.
81
FRLA
surv
ival
pro
bab
ility
inti
alh
eig
ht(
cm)
1020
3040
5060
initial diameter (mm)5 10 15 20 25 30
0.50.60.70.8 0.90.95 0.99
510
1520
2530
initial diameter (mm)
10
20
30
40
50
60intial height (cm)
00.
20.
40.
60.
81
POFR
surv
ival
pro
bab
ility
number of leaves10 20 30 40
0.90.95
0.99
inti
alh
eig
ht
(cm
)10
2030
4050
60QULO
510
1520
2530 35 40
number of leaves
10
20
30
40
50
60
intial height (cm)
00.
20.
40.
60.
81
surv
ival
pro
bab
ility
ACNE
1
23
45
initial diameter (mm)
10
20
30
40
50
60
intial height (cm)
00.
20.
40.
60.
81
surv
ival
pro
bab
ility
initial diameter (mm)1 2 3 4 5
0.7 0.8 0.9 0.95 0.99
inti
alh
eig
ht
(cm
)10
2030
4050
60
inti
alh
eig
ht(
cm)
510
1520
number of leaves0 2 4 6 8 10
0.5 0.6 0.7 0.8 0.9 0.95
0.99
02
46
810
number of leaves5
10
15
20
intial height (cm)
00.
20.
40.
60.
81
FRLA
surv
ival
pro
bab
ility
inti
alh
eig
ht(
cm)
1020
3040
5060
initial diameter (mm)5 10 15 20 25 30
0.50.60.70.8 0.90.95 0.99
510
1520
2530
initial diameter (mm)
10
20
30
40
50
60intial height (cm)
00.
20.
40.
60.
81
POFR
surv
ival
pro
bab
ility
number of leaves10 20 30 40
0.90.95
0.99
inti
alh
eig
ht
(cm
)10
2030
4050
60QULO
510
1520
2530 35 40
number of leaves
10
20
30
40
50
60
intial height (cm)
00.
20.
40.
60.
81
surv
ival
pro
bab
ility
ACNE
1
23
45
initial diameter (mm)
10
20
30
40
50
60
intial height (cm)
00.
20.
40.
60.
81
surv
ival
pro
bab
ility
initial diameter (mm)1 2 3 4 5
0.7 0.8 0.9 0.95 0.99
inti
alh
eig
ht
(cm
)10
2030
4050
60
inti
alh
eig
ht(
cm)
510
1520
number of leaves0 2 4 6 8 10
0.5 0.6 0.7 0.8 0.9 0.95
0.99
02
46
810
number of leaves5
10
15
20
intial height (cm)
00.
20.
40.
60.
81
FRLA
surv
ival
pro
bab
ility
inti
alh
eig
ht(
cm)
1020
3040
5060
initial diameter (mm)5 10 15 20 25 30
0.50.60.70.8 0.90.95 0.99
510
1520
2530
initial diameter (mm)
10
20
30
40
50
60intial height (cm)
00.
20.
40.
60.
81
POFR
surv
ival
pro
bab
ility
number of leaves10 20 30 40
0.90.95
0.99
inti
alh
eig
ht
(cm
)10
2030
4050
60QULO
510
1520
2530 35 40
number of leaves
10
20
30
40
50
60
intial height (cm)
00.
20.
40.
60.
81
surv
ival
pro
bab
ility
ACNE
1
23
45
initial diameter (mm)
10
20
30
40
50
60
intial height (cm)
00.
20.
40.
60.
81
surv
ival
pro
bab
ility
initial diameter (mm)1 2 3 4 5
0.7 0.8 0.9 0.95 0.99
inti
alh
eig
ht
(cm
)10
2030
4050
60
Merced river
Growth patterns did not vary systematically by treat-ment factors, but some factors – block/elevation and ini-tial size - were important for individual species (Figure 1).
a C K n O w L e d g e m e n t s
CALFED Recipient Agreement ERP-02-P12-D
GCAP Services, Inc.
Dr. V.T. Parker (SFSU) for input and equipment
Tom Griggs (River Partners) and Dr. Joe McBride (UC Berkeley) for input to the study design
Shelly Schubert (CDFG) and Harry Hose for their invalu-able fieldwork.
John C. Stella1, Zooey E. Diggory2, Marie D. Reil2, Bruce K. Orr2, John J. Battles3
Restoration of a Severely Degraded LandscapeRevegetation of Native Riparian Trees on Floodplain Dredge Spoils in California’s Central Valley
The Merced River Ranch, (RM 51 to 50) downstream of Crocker-Huffman Dam.
Experimental Design and MethodsThe MRR revegetation experiment tests the effects of depth to groundwater, irrigation duration, and weed reduction treatments on the survival, growth, and water stress, as indicated by xylem water potential, of four riparian tree species.
Altered hydrology, reduced sediment supply, and degraded floodplain conditions in the Mer-ced River’s dredger tailings reach (DTR) strongly limit riparian vegetation establishment and extent, and impact the floristic and structural composition of riparian habitat.
Channel and floodplain restoration is current-ly being planned for the Merced River Ranch (MRR), a 129 ha (318 ac) site with degraded floodplain conditions typical of the DTR. The MRR was purchased by California Department of Fish and Game (CDFG) in 1998 as a source of coarse sediment for future river restoration projects and as a floodplain restoration site.
How do site conditions affect revegetation performance?
Introduction
CHaLLengeEven under restored floodplain conditions, natural recruitment of pioneer riparian plant species is not expected to significantly contribute to the development of the riparian corridor due to reductions in flood flow frequency and magnitude, chang-es in flood flow timing, and lack of fine sediment. Active revegetation of restored floodplains will be necessary to recreate a riparian corridor that provides multiple ecosystem benefits, and to enhance the large areas of the floodplain too far from the river to experience flooding under the regulated flow regime.
sOLutiOnA riparian revegetation experiment was undertaken to reduce uncertainty in how site conditions will affect revegetation performance, and as a response to the rec-ommendations of the Merced River Adaptive Management Forum to improve the linkages between scientific input and project design, conduct active experiments
with revegetation design when the opportunity exists, and increase the amount of transferable information generated from the Merced River. This poster summarizes
the results of the 3-year experiment.
Increase scientific understanding of factors limiting the success of riparian revegetation on restored floodplains.
Provide transferable scientific information that will reduce the scientific uncertainty in future revegetation projects.
•
•
s t u dy g O a L s
Two experimental areas (Block 1 and Block 2) were selected and graded in areas that were representative of overall site conditions but that did not require the disturbance of wetland habitat or high-quality riparian vegetation.
Site Set Up
sPeCiesSixty of each species were planted ran-domly on 2 m-centers in each relative elevation treatment plot, for a total of 1,440 individual plants.
POFRFremont
cottonwoodPopulus fremontii
2-3 ft cuttings
QuLOValley oak
Quercus lobata1 year old
container stock
aCneBox elder
Acer negundo 1 year old
container stock
FRLAOregon ash
Fraxinus latifolia1 year old
container stock
s P e C i e s s e L e C t i O n C r i t e r i a :
Dominant or co-dominant com-ponents of Central Valley mixed riparian forestsExhibit different life history traitsOccur within a range of geomor-phic recruitment positions on riv-er banks and floodplainsKnown to occur naturally at the Merced River Ranch
1.
2.3.
4.
treatments anaLysisEach block contained three elevation above groundwater treatment plots.
Irrigation and weed control treatments were randomly assigned, stratified by species.
NOTE: Elevations were selected to replicate the range of elevations above groundwater likely to occur once the tailing piles have been removed for restoration purposes.
CategoryElevation Above
GroundwaterLow (L) ~1 m above groundwater
Medium (M) ~2 m above groundwater
High (H) ~4 m above groudnwater
Analysis of variance (ANOVA) models were used to test: whether seedlings and cuttings varied significantly in ini-tial size (height, basal diameter and number of leaves upon planting) by the location where they were planted and the effects of experimental treat-ments on water potential. Analysis of covariance (ANCOVA) models were used to test differences in growth be-tween treatment groups. A Cox pro-portional hazard model, a flexible re-gression model for assessing the effects of multiple predictors on time-to-event data, was used to analyze differences in seedling survival between treatment levels in each year of the experiment.
Weed control mat installed at planting
Manual weed removal during the growing season within a 1 m2 area around the plant
•
•
1/3 of plants received 1 year of irrigation
1/3 of surviving plants from Year 1 received 2 years of irrigation
1/3 of suviving plants from Year 2 received 3 years of irrigation
Randomized planting scheme and treatment application for the experiment.
Hypothesis1 Experimental Treatments
Treatment LevelsMonitoring
Metric2
MRR floodplains restored to functional elevations will provide improved condi-tions for revegetated plants (i.e., shorter distances to groundwater), resulting in increased establishment and survival.
Floodplainelevation
Low, middle, and high floodplain relative elevation plots
Plant survival, growth, xylem water potential
Controlling weeds in the immediate vicinity of plantings increases plant surviv-al and growth because of reduced competition from herbaceous plants.
Weedreduction
Weed reduction applied; weed reduction not applied
Plant survival, growth, % cover of weeds
Irrigating seedlings and cuttings after planting will increase survival and growth because of reduced moisture stress. Plants will require irrigation for at least one year to become established. Plants irrigated for greater than one year will demonstrate increased survival over plants irrigated for only one year.
Irrigation Drip irrigation during the growing season for one, two or three years
Plant survival, growth, xylem water potential
1 The hypotheses and factors tested in the experiment were developed in response to the establishment needs of pioneer riparian tree species and designed to answer some of the primary current unknowns in floodplain revegetation specific to dredge tailing areas (AMFSTP 2002). Experimental treatments were refined based on the planting plans, experiences, and results of other Central Valley revegetation efforts on restored floodplain surfaces.
2 Project monitoring was conducted during the plant growing season (April through October) of 2004-2006. Substrate texture and nutrients, groundwater elevation, swale pond and river stage, ambient air temperature, and relative humidity were also monitored for the experiment.
Weed reduction:
No weed reduction:
r e L at i v e e L e vat i O nBased on the significant effect of relative elevation on third year survival, and with the goals of minimizing the need for irrigation and promoting long-term survival of revegetated plants, we recommend that floodplains at the MRR that are to be revegetated to elevations not more than 2 m above groundwater.
i r r i g at i O nWe recommend that at least two years of irrigation be provided to all spe-cies regardless of floodplain elevation. On higher surfaces (>2 m), three or more years of irrigation may be necessary, particularly to establish ACNE and POFR.
w e e d r e d u C t i O nWeed reduction did not emerge as a significant predictor of growth or mor-tality, except as a minor influence on QULO growth. Establishment of weeds at potting soil delivery areas as well as recruitment of cottonwood and wil-low seedlings in, but not outside, the experimental area, suggest that im-proved conditions provided by soil amendments and irrigation will facilitate the recruitment of both native and non-native species. Weed control may be required in areas expected to support a dense cover of weeds, (e.g., wet spots, areas with sand substrates, or where existing vegetation is nearby.) To minimize the introduction of non-native invasive weed species to the MRR, we recommend restricting vehicular access to the site to the greatest extent possible. Further, any soil amendment brought to the site should be certified as sterilized and/or weed-free. Since this is difficult to document, we recommend that, when feasible, organic material from on-sitebe used rather than imported material.
s i z e t H r e s H O L d sTo ensure that adequate survival rates are achieved, we recommend that all cuttings and container stock used in MRR revegetation efforts meet the size thresholds indicated in the logistic regression survival models and summa-rized in Table 3. Where these size thresholds are not met, cuttings or contain-er stock should be rejected and/or grown out in the nursery until they reach adequate sizes.
Recommendations
Condition Thresholds aCne FRLA POFR QuLOHeight -- > 12 cm -- <50 cm
Diameter > 2.5 mm >2 mm >15 mm >5 mmPredicted survival if thresholds met 95% 80% 80% 90%
OTHER:POFR should be planted with less than 50% of the cutting length above ground.In this case, taller QULO plants may have been root-bound.
••
TABLE 3. Initial size and condition thresholds to achieve desired 1st year survival rates.
RESULTS
The influence of initial planting size on 1st year survival underscores the need for planting stock to be healthy and of adequate size to endure the harsh site conditions (see Recommendations). The strong effect of the irrigation treatment on 2nd year sur-vival suggests that irrigation provides sufficient benefits to plants (such as accelerated root growth and/or adequate water supply) that they are able to overcome, or are no longer adversely affected by, greater distances to groundwater (Table 1). The signifi-cant effect of relative elevation on survival in the third year may be a result of plant roots having finally reached permanent groundwater at the lower elevation treatment plots. In this case, irrigation may be necessary to achieve the survival rates required by restoration project environmental compliance documents and permits, but shorter distances to groundwater may be needed to achieve long-term survival, growth and/or canopy density objectives.
Time series from a photo moni-toring station (April 2004 to October 2005).
0 20 40 60 80 100 120 140
050
100
150
200
250 ACNE
0 20 40 60 80 100 120 140
050
100
150
200
250 FRLA
0 20 40 60 80 100 120 140
050
100
150
200
250 POFR
0 20 40 60 80 100 120 140
050
100
150
200
250 QULOHei
ght
(cm
)
Weeks since start of experiment
Yr 1 (2004) Yr 2 (2005) Yr 3 (2006)
Yr 1 (2004) Yr 2 (2005) Yr 3 (2006)Yr 1 (2004) Yr 2 (2005) Yr 3 (2006)
Yr 1 (2004) Yr 2 (2005) Yr 3 (2006)
Low (1m from groundwater)Mid (2m from groundwater)High (4m from groundwater)
0 20 40 60 80 100 120 140
050
100
150
200
250
0 20 40 60 80 100 120 140
050
100
150
200
250 ACNE
0 20 40 60 80 100 120 140
050
100
150
200
250 FRLA
0 20 40 60 80 100 120 140
050
100
150
200
250 POFR
0 20 40 60 80 100 120 140
050
100
150
200
250 QULOHei
ght
(cm
)
Weeks since start of experiment
Yr 1 (2004) Yr 2 (2005) Yr 3 (2006)Yr 1 (2004) Yr 2 (2005) Yr 3 (2006)
Yr 1 (2004) Yr 2 (2005) Yr 3 (2006)Yr 1 (2004) Yr 2 (2005) Yr 3 (2006)Yr 1 (2004) Yr 2 (2005) Yr 3 (2006)Yr 1 (2004) Yr 2 (2005) Yr 3 (2006)
Yr 1 (2004) Yr 2 (2005) Yr 3 (2006)Yr 1 (2004) Yr 2 (2005) Yr 3 (2006)
Low (1m from groundwater)Mid (2m from groundwater)High (4m from groundwater)
Low (1m from groundwater)Low (1m from groundwater)Mid (2m from groundwater)Mid (2m from groundwater)High (4m from groundwater)High (4m from groundwater)
GrowthSurvival
Survival Period Treatment aCne FRLA POFR QuLO
Year 1 (Apr–Oct 2004) All irrigated 1 year 0.96±0.01 0.78±0.03 0.58±0.04 0.96±0.01Year 2 (Apr–Oct 2005) Irrigated 1 year 0.65±0.07 0.44±0.12 0.77±0.07 0.83±0.04
Irrigated 2 years 0.65±0.07 0.44±0.12 0.77±0.07 0.83±0.04Year 3 (Apr–Oct 2004) Irrigated 1 year 0.67±0.08 0.92±0.05 0.69±0.09 0.93±0.03
Irrigated 2 years 0.45±0.1 0.77±0.06 0.76±0.07 0.78±0.05Irrigated 3 years 0.69±0.06 0.84±0.05 0.78±0.07 0.92±0.03
Final Survival (Apr 2004–Oct 2006)
Irrigated 1 year 0.42 0.32 0.31 0.74Irrigated 2 years 0.41 0.52 0.41 0.74Irrigated 3 years 0.64 0.56 0.42 0.87
The initial size of cuttings and container stock had a strong ef-fect on first year survival and growth for most species.
Initial Size
aCne+ Seedlings with a 2 mm diameter were over twice
as likely to die in the first year as one with a di-ameter of 3 mm.
FRLA+ An increase in stem height of 1 cm resulted in a
16% lower probability of mortality.+ An individual with 2 more leaves than another
seedling had less than half the chance of dying in the first year.
POFR+ For two cuttings that differ in stem diameter by 5
mm, the thinner one was 3.5 times more likely to die in the first year compared to the thicker one.
+ Survival advantages due to height appeared to be modest. Plants with shorter above-ground stem height had a higher chance of survival than ones with more above-ground stem exposed.
QuLO- For two seedlings differing by 10 cm at planting,
the shorter one had half the probability of dying in the first year compared to the taller one.
+ A seedling with 10 fewer leaves than another was half as likely to die in the first year.
Correlations (+/-) between initial size param-eters and seedling survival by species (based on 2-yr results). Modeling of survival rates as a function of initial size provides guidelines for the height, diameter, and number of leaves that the four species should have in order to attain certain survival rates.
Water potential values were significantly influenced by species and month.
While effects of irrigation and relative elevation treatments on water potential values were not statistically significant, re-sults were suggestive of an ef-fect (Figure 3).
In general, POFR has higher wa-ter potentials (i.e., is less water stressed) than the other spe-cies. This difference and high pre-dawn values regardless of relative elevation or irrigation treatment level suggest that POFR plantings (at least those that survived to September 2005) had the deepest root-ing system and had reached a reliable groundwater source, but may be the result of wider xylem which do not permit POFR to build up high xylem pressure and therefore result in less negative water potential values.
Water StressACNE
Pre-DawnMid-Day
-4
-3
-2
-1
0
Irr Not Irr NotJune Sept
xyle
mw
ater
po
ten
tial
(MPa
)
FRLA
-4
-3
-2
-1
0
Irr Not Irr NotJune Sept
POFR
-4
-3
-2
-1
0
Irr Not Irr NotJune Sept
QULO
-4
-3
-2
-1
0
Irr Not Irr NotJune Sept
FIGURE 3. Xylem water potential values for irrigation treatment groups. Points shown are the means of all treatment groups (+/- 1SE). Weed reduction did not emerge as a significant predictor of survival or
growth for any species.
The lack of effect on survival is somewhat surprising, since weeds have been report-ed as having severe negative impacts on other revegetation projects in the Central Valley, but may be explained by the harsh conditions at the MRR. In comparison with most floodplains, the MRR does not support much herbaceous vegetation. The coarse substrate and extreme summer temperatures appear to restrict the es-tablishment of perennial herbaceous vegetation, although annual species do estab-lish after winter and spring rains. It could be that the harsh site conditions inhibit weed establishment to the extent that weeds cannot out-compete planted vegeta-tion, particularly container stock that is usually one to two years old at outplanting.
Mortality was influenced most strongly by: initial planting size (in Year 1); irrigation treatment (in Year 2); andrelative elevation (in Year 3).
•••
FIGURE 1. Plant height growth by treatment over the experiment. Points shown are the means of all treatment groups (± 1SE).
No weed control mat or manual weed removalWeeds were allowed to grow to the extent that they did not invade weed-reduc-tion-treatment plants
•
•
Weed Percent Cover
Plot Elevation Year Weed Percent Cover Category**0% 1-5% 6-10% 11-25% 26-50% 51-75% 76-100%
BLOCK 1
Low2004 94 3 0 3 0 0 02005 15 17 22 18 15 8 52006 3 0 7 28 31 25 7
Medium2004 87 10 2 2 0 0 02005 24 13 23 23 12 4 12006 6 8 16 31 22 16 3
High2004 87 11 0 3 0 0 02005 28 22 18 20 7 5 12006 11 6 17 25 27 13 2
BLOCK 2
Low2004 83 8 2 2 3 2 12005 17 12 21 18 21 8 42006 7 5 7 16 35 25 6
Medium2004 98 1 2 0 0 0 02005 56 16 17 8 3 1 02006 50 12 24 11 3 1 0
High2004 97 1 1 2 0 0 02005 26 25 28 11 8 2 02006 31 3 26 24 10 7 0
* Only those experiment plants without the weed reduction treatment are included in percent cal-culations.
** A modified Braun-Blanquet (1965) cover class system was used, and included the following classes: (0) 0%, (1) 1–5%; (2) 6–10%; (3) 11–25%; (4) 26–50%; (5) 51–75%; (6) 76–100%.
TABLE 2. Percent of plants within each weed percent cover category.*
TABLE 1. End-of-year survival (±1SE) by species and irrigation treatment for all three years.*
This temporal change in the primary drivers of mortality is the result of the interac-tion of the treatment regimes with the plants’ growth patterns and changing vulner-ability profiles over time.
1 SUNY College of Environmental Science and Forestry, Syracuse, NY; 2 Stillwater Sciences, Berkeley, CA3 Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA
FIGURE 2. Response surfaces (left series) and contour plots (right series) for the best logistic regression survival models.
groundwater
Low (L)
Medium (M)
High (H)
~4 m
~2 m~1 m
Newly graded and planted vegetation plot at the Merced River Ranch.
No positive irriga-tion effect (i.e., higher growth with increased irrigation duration) is apparent until the third year.
Differences in growth between eleva-tion levels are more apparent. In general, growth is greater for stems on lower sur-faces compared to upper surfaces.*Values are Kaplan-Meier survival estimates and represent the proportion of those plants alive at the beginning of each growing season (April)
still alive at the end of the growing season (October). Final survival represents the survival of the original cohort over the three years.
Recommended