growth of native and exotic plants during the 2000 low steady summer flows or: be careful what you...
TRANSCRIPT
Growth of native and exotic plants during the 2000 Low Steady Summer Flows
Or: Be careful what you ask for…
Marianne E. Porter Michael J.C. Kearsley
Dept. of Biol. Sciences Northern AZ. University
Flagstaff, AZ
Possible LSSF Experiment Outcomes:
* Bla Bla Bla native fish recruitment
* Bla Bla Bla seasonal hydrology
* Bla Bla Bla near-shore current velocity
* Bla Bla Bla increased water temperature
*Recruitment of clonal herbaceous species (Equisetum, Juncus, Phragmites)
*Recruitment of exotic species (Tamarix, Alhagi) in near shore areas
Importance of plant colonization
Vegetated shoreline: vegetation (primarily Tamarix chinensis) in or directly over the water, either rooted or inundated. May have intermittent stretches of other shoreline types.
Densities of humpback chub are nearly double those found in other shoreline types (Converse et al 1998).
31,500
19,000
8,000
River Stage
Pre-Low Flows Conditions
Pre-Low Flows Conditions
Research Questions:
Do plants colonize newly available habitat?(8 kcfs – 19 kcfs)
Nature of these colonists? Native / Exotics?Clonal / Seed-dispersed?
Impacts of a short-duration high flow?
Effects of low flows on extant vegetation at the31 kcfs stage elevation?
Sampling Transect Design31 kcfs
19 kcfs
8 kcfs
= 0.25 m2 Plot
5 – 18 Plots / Transects
6 – 14 Transects / Site
Sampled Monthly June – Sept 2000 April 2001
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Flo
w (
kcf
s)
0
10
20
30
Study Period Hydrograph
Sampling
Nearshore Vegetation Study Sites
Data Analysis
Repeated Measures AOV on Plant Densities
Time, Site, Time*Site Data Transformations
All Species Individual Species Tamarisk, Equisetum
Plant colonization: June
Plant colonization: August
Date
May Jun Jul Aug Sep Oct Nov
Pla
nt
Den
sity
(st
ems
/ m2 )
0
100
200
300
400
500Clonal species Tamarisk All species
Plants Below 19 kcfs
High elevation Equisetum
All Equisetum
Date
May Jun Jul Aug Sep Oct Nov
Equisetum
Den
sity
(st
ems
/ m2 )
0
10
20
30
40
50
19,000 cfs31000 cfs Below 19,000 cfs
Date
May Jun Jul Aug Sep Oct Nov
Tamarix
Den
sity
(st
ems
/ m2 )
0
500
1000
1500Cathedral lowCathedral allBadger lowBadger all
Low and High Elevation Tamarisk
Date
May Sep Jan May
Exo
tic
Den
sity
(st
ems
/ m2 )
0
500
1000
1500CathedralBadgerSoap CreekAnasazi LCR Tanner
Winter Mortality is Low
Date
May Sep Jan May
Exo
tic
Den
sity
(st
ems
/ m2 )
0
500
1000
1500Cathedral allCathedral lowBadger allBadger low
River’s Edge Mortality
Conclusions
•Plants colonized areas below 19,000 cfscreating subadult fish habitat
•Colonists primarily Tamarisk
•Clonal herbaceous species were slower
•Fall high flows reduced plant densities
•Winter mortality was low for all species
•Recreation impacts of near-shore plants