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Do soil communities differ between native and invasive dune grasses on
Great Lakes sand dunes?
Matthew L. Reid & Sarah M. Emery
MIPN Invasive Plant Symposium
December 10, 2015
Exotic Plants
www.inps.gov
www.iextension.entm.purdue.edu
Plant-Plant Competition
Plant-Herbivore Interactions
Plant-Mutualist Interactions
Plant Host-Parasite Interactions
Plant-Plant Competition
Plant-Herbivore Interactions
Plant-Mutualist Interactions
Plant Host-Parasite Interactions
Plant-Plant Competition
Plant-Herbivore Interactions
Plant-Mutualist Interactions
Plant Host-Parasite Interactions
Plant-Soil Feedbacks
Herbivores Parasites
Mutualists Competitors
Plant-Plant Competition
Plant-Mutualist Interactions
Plant-Herbivore Interactions
Plant Host-Parasite Interactions
Invasive Plants & Soil Interactions
• Enemy Release
– Root herbivores & parasites
• Reduced Dependence on Native Mutualists
– But may utilize native mutualists to their advantage
Belowground Interactions
Arbuscular mycorrhizal fungi Nematodes
www.ipm.iastate.edu http://mycorrhizas.info/vam.html
Nematode Functional Groups
Plant-parasite
Fungal-feeder Bacteria-feeder
Predator
www.wageningenur.nl www. plpnemweb2.ucdavis.edu/nemaplex
www.und.edu www.urbanext.illinois.edu
Enemy Release
Plant-parasite
www.wageningenur.nl
Invasive Plants Fewer plant-parasites
Arbuscular Mycorrhizal Fungi
• Nutrient uptake
• Bioprotection
Reduced Mycorrhizal Dependence
Invasive Plants Lower AMF abundance (root colonization, spores)
Study System
www.earthobservatory.nasa.gov
Aquatic-terrestrial interface
Extent 275,000 acres of dunes in MI
Dune Grasses
Ammophila breviligulata Leymus arenarius
Native Exotic
Leymus arenarius
• Biomass
• Height
• Leaf length & width
• Flower production
• Seed mass
Primary Succession
Ammophila colonizes & stabilizes dune
Ammophila dieback
Colonization by later successional species Emery. 2010. Nature Education Knowledge.
Primary Succession
Ammophila colonizes & stabilizes dune
Ammophila dieback
Colonization by later successional species Emery. 2010. Nature Education Knowledge.
Research Questions
1. Is invasion by Leymus associated with different soil communities?
2. Can invasion by Leymus be facilitated by belowground interactions with arbuscular mycorrhizal fungi and nematodes?
Research Questions
1. Is invasion by Leymus associated with different soil communities?
– Field survey
2. Can invasion by Leymus be facilitated by belowground interactions with arbuscular mycorrhizal fungi and nematodes?
– Greenhouse experiment
Research Questions
1. Is invasion by Leymus associated with different soil communities?
– Field survey
2. Can invasion by Leymus be facilitated by belowground interactions with arbuscular mycorrhizal fungi and nematodes?
– Greenhouse experiment
Hypotheses
1. Reduced mycorrhizal dependence
– Leymus will have a weaker association with AMF.
2. Enemy release
– Leymus soil will harbor fewer plant-parasitic nematodes.
2014 Field Survey
Field Survey Methods
• Vegetation survey
• 10 composite soil cores
– Nematodes and roots for AMF
• Collect tiller for nutrient analyses
20 m
1m2
Field Survey Methods
• AMF staining via vinegar-ink
• Nematode extraction via sugar flotation
• Functional group ID
• Analyses
– Mixed model ANOVA
• Fixed effect: Native (Ammophila)/Exotic (Leymus)
• Random effect: Site, Site*Species
• Response – AMF: Root colonization
• Response – Nematodes: Abundance per functional group
Results – Root Colonization
• Site and site*species interaction non-significant
• No difference in levels of root colonization
% R
oo
t C
olo
niz
atio
n
Ammophila Leymus
0
10
20
30
40
p = 0.330
Results – Total Nematodes
• Site and site*species interaction non-significant
• No difference in total nematode abundance
p = 0.5864
Ammophila Leymus 0
20
40
60
80
100
Nem
ato
de
s/1
00
mL s
an
d
Ammophila Leymus 0
10
20
30
40
50
60
Nem
ato
des/1
00m
L s
and
Results – Plant Parasites
• Site and site*species interaction non-significant
• No difference in abundance of plant-parasites
p = 0.559
Results – Predators
• Site and site*species interaction non-significant
• No difference in abundance of predators
p = 0.415
Ammophila Leymus 0
5
10
15
20
Nem
ato
des/1
00m
L s
and
Results – Bacteria-Feeders
• Site and site*species interaction non-significant
• Marginal difference in abundance
p = 0.066
Ammophila Leymus 0
10
20
30
Nem
ato
de
s/1
00
mL s
an
d
Field Survey Results
• No evidence supporting reduced mycorrhizal dependence
• No evidence supporting release from plant-parasitic nematodes
• Trend of increased abundance for bacterial-feeding nematodes – Litter quality or quantity?
– Root exudates?
– Root turnover?
Field Survey Results
• Plant Tissue Properties
Site Species % Nitrogen % Phosphorus
Green Point Dunes Leymus 0.90% 0.13%
Green Point Dunes Ammophila 1.13% 0.12%
Ludington State Park Leymus 0.92% 0.08%
Ludington State Park Ammophila 1.14% 0.11%
Meinert Park Leymus 1.66% 0.10%
Meinert Park Ammophila 1.52% 0.08%
Field Survey Results
• Soil Properties
Site Species Organic Matter Total Nitrogen
Green Point Dunes Leymus 0.52% 0.009%
Green Point Dunes Ammophila 0.67% 0.009%
Ludington State Park Leymus 0.28% 0.013%
Ludington State Park Ammophila 0.34% 0.009%
Meinert Park Leymus 0.12% 0.015%
Meinert Park Ammophila 0.17% 0.008%
Nematode Community Composition
Dorylaimoides sp. Acrobeles sp.
Trophurus sp.
2015 Field Survey
Research Questions
1. Is invasion by Leymus associated with different soil communities?
– Field survey
2. Can invasion by Leymus be facilitated by belowground interactions with arbuscular mycorrhizal fungi and nematodes?
– Greenhouse experiment
Hypotheses
1. Leymus will be less susceptible to plant-parasitic nematodes (PPN).
2. Leymus will be less dependent on arbuscular mycorrhizal fungi (AMF).
3. Leymus will have altered interactions with AMF and PPN in combination.
Methods
• Treatments:
–Native Ammophila
– Invasive Leymus
AMF
PP
N
-AMF -PPN
+AMF -PPN
+AMF +PPN
-AMF +PPN
AMF = Rhizophagus intraradices
• Obtained from INVAM at West Virginia University
PPN = Pratylenchus penetrans
• Migratory endoparasite
www.nematode.unl.edu
• Replication: 10 per treatment combination
• Data Analyses: 3-way ANOVA
Methods
• Response variables of interest
– Root colonization
– Nematode abundance
– Biomass
• Root, shoot, total
– Other traits
• Root architecture, shoot characteristics
Methods
Direct effect of AMF
p = 0.904
Direct effect of AMF
• AMF
– (P = 0.015)
• AMF*Species
– (P = 0.444)
– Leymus 30% increase
– Ammophila 41% increase
Direct effect of PPN
• PPN
– (P < 0.001)
• PPN*Species
– (P = 0.089)
– Leymus 50% decrease
– Ammophila 63% decrease
AMF enhance growth in the presence of plant-parasitic nematodes
Hypotheses
1. Leymus will be less susceptible to plant-parasitic nematodes (PPN).
– Some support
2. Leymus will be less dependent on arbuscular mycorrhizal fungi (AMF).
– Not supported
3. Leymus will have altered interactions with AMF and PPN in combination.
– Supported
Implications
• Potential competitive displacement
• Altered successional trajectories?
• Management
– Clearcast herbicide, seed head clipping
Acknowledgments
Katie Arstingstall
Brad Gottshall
Andrea Howes
Erin Kinnetz
Land Managers
Michigan DNR
Grant Traverse Regional Land Conservancy
Muskegon County Parks
Questions?