Are we creating the ideal conditions for Arundo donax for Arundo donax invasion in California? ... C...
Transcript of Are we creating the ideal conditions for Arundo donax for Arundo donax invasion in California? ... C...
Are we creating the idealconditions for Arundo donax
invasion in California?
Gretchen CoffmanRichard F. Ambrose
Tom DudleyPhil W. Rundel
UCLA
Arundo (Arundo donax)• Indigenous to northern
India and southern Nepal, a Wet-Dry Tropical Climate
• Bamboo-like member of Grass family
• 8-10 meters tall• Spreads via massive
rhizomes
PROBLEM
• Introduced globally for use in erosion control, ceilings, roofs, fences, baskets, and around hot springs
• Successful invader in river systems of Southern CA in past 35 years
Why is Arundo So Successful?• Easily dispersed via rhizomes• Disturbance colonizer • Successful in Mediterranean-type
climate– fast growing (up to 7 cm per day)– reaches >8 m in height after only
a few months– grows 3-4 times faster than native
plants• Outcompetes indigenous plant
species for resources Bell 1994
Invasion Hypothesis
Increased water, nutrients, light, and fire in riparian ecosystems have made a significant contribution to the successful invasion of Arundo (Arundo donax) throughout river systems in Mediterranean-type climates like California
Study Approaches
• Experimental study -• large-scale field experiment (2002-5)
• Correlational field study -• opportunistic fire study (2003-4)
Riparian Field Experiment
• Large-scale field experiment (0.4 ha)– 1,152 plants – 8 competition treatments (4 species)– 3 nutrient treatments– 2 water treatments– 2 light treatments
Study Design1 2 3 4 5 6 7 8 9
M A C C M A W A M M W A A A M A C C C C C A M M A A A A W W C A W A C A A C M M W C A M W W W WL H L L H L H H L H H L H L H L
A M C C A M A W M M A W A A A M C C C C A C M M A A A A W W A C A W A C M W M M M A C W W W W W
M M W A M M C A W A A A M A M A A A W W W A C C C C C A M M A A M A C C M A W M W W W W A M C AL H H L L H L H H L H H L H L L
M M A W M M A C A W A A A M C W A A W W A W C C C C A C M M A A A M C C A M A C W W W W W C A C
C C M A C A W C W A M A M M C W W W C C W A C C M C M M A A A A M M C A W W M A C A W W A A W AH L L H L H L H H H L L L H H L
C C A M A C A M A W A M M M A M W W C C A W C C W A M M A A A A M M A C W W A M A C W W A A A W
C A C A A A W W M M M M W A W W A A M A W A A A C C W A C C C A M A M A M W C A C C W W A W M ML L L L L H H L H H H L H H L H
A C A C A A W W M M M M A W W W A A A M A W A A C C A W C C A C A M A M A C W M C C W W C M M M
W A A A C A C C C A M M C C C A W A W W A A C C M A W W M A A A C A M M W A M M A W M A M C W WH H L L H H L L H L L H L H L
A W A A A C C C A C M M C C M W A W W W A A C C A M W W A M A A A C M M A W M M M C A M W A W W
W A C C W A W A C W M M M M A A C A M A A A W A W C A A C A C C W W W W W W C C M A C A M M M AH H H L L L H L L H H L H L H L
A W C C M C A W M A M M M M A A A C A M A A A W A M A A A C C C W W W W W W C C A M A C M M A M
LEGEND:
A = Arundo donax (Giant Reed) = Open treatmentC = Black Cottonwood (Populus balsamifera ssp. trichocarpa ) = Shade treatment (80%)M = Mule Fat (Baccharis salicifolia ) = Plant grouping numberW = Red Willow (Salix laevigata ) C AH = High N fertilizer treatment H = Plant groupingL = Low N fertilizer treatment A C
249 250 251245 246 247 248241 242 243 244
200 201 202 203
153 154 155
193 194 195 196 197 198 199
149 150 151 152145 146 147 148
104 105 106 107
57 58 59
97 98 99 100 101 102 103
53 54 55 5649 50 51 52
261 262 263 264257 258 259 260253 254 255 256
213 214 215 216209 210 211 212205 206 207 208
165 166 167 168161 162 163 164157 158 159 160
117 118 119 120113 114 115 116109 110 111 112
69 70 71 7265 66 67 6861 62 63 64
21 22 23 2417 18 19 2013 14 15 16
11
10 11 12
60
108
156
204
252
Groundwater wellsand soil moisture sensors
Measurements• Biomass• Growth• Soil moisture• Groundwater levels• Soil grain size• Leaf area• Leaf nutrient
content• Water potential
Plant Species
Dry
Abo
vegr
ound
Bio
mas
s (g
)
0
200
400
600
800
1000
1200
1400
1600
High Soil Moisture Low Soil Moisture
Arundo donaxBlack
CottonwoodMulefat
Red Willow
Water AvailabilitySoil Moisture
Light Availability
Plant Species
Dry
Abo
vegr
ound
Bio
mas
s (g
)
0
200
400
600
800
1000
1200
1400
1600
1800
Arundo donaxBlack
CottonwoodMulefat
Red Willow
Plant Species
0
200
400
600
800
1000
SHADEOPEN
Arundo donaxBlack
Cottonwood MulefatRed Willow
Low Soil MoistureHigh Soil Moisture
Summer 2003
Nutrient Availability
Plant Species
Dry
Abo
vegr
ound
Bio
mas
s (g
)
0
200
400
600
800
1000
1200
1400
1600
1800
2000
Arundo donaxBlack
Cottonwood MulefatRed Willow
Plant Species
0
200
400
600
800
1000
NO FERTILIZER LOW FERTILIZER HIGH FERTILIZER
Arundo donaxBlack
Cottonwood MulefatRed Willow
High Soil Moisture Low Soil Moisture
Summer 2003
1
23 46 5
7-1415
Fire Studies• Documented
historical spread of fire through Arundoin 9 rivers in Southern CA
• Measured growth, density and % cover of Arundo vs. natives after fire
Extent of fire
Post-Fire Growth
Time after FireNovember
DecemberJanuary
February March April May June JulyAugust
September
Ave
rage
Ran
dom
Hei
ght (
cm)
-50
0
50
100
150
200
250
300
350
Arundo donaxNative Plant SpeciesTrends over time
Time Post-fire (2004)
March April June July August SeptemberM
ean
Den
sity
(ste
m/m
2 )
0
5
10
15
20
25
30
Arundo donaxNative Plant SpeciesTrends over time
Plant Abundance
0
20
40
60
80
Arundo donaxNative Plants
Summer 2003Pre-fire
July 2004Post-fire
Time
Plan
t Abu
ndan
ce (p
erce
nt c
over
/m2 )
Acknowledgements• Funding:
– UC Water Resources Center– State Coastal Conservancy– Santa Clara River Trustee Council– The Nature Conservancy– University Research Expedition Program– Rico International– UCLA/UCSB
• Thanks to my many field assistants and volunteers in the Western Cape, South Africa and Southern California who made this research possible!