PLANTS!!
How do they Interact?
Presented by Ashwana
Fricker
Background
Grass: A monocotyledenous green plant in the family
Poacaea
Forb: Any non-woody flowering plant that is not a grass
Background
Grass: A monocotyledenous green plant in the family
Poacaea
Forb: Any non-woody flowering plant that is not a grass
• Competitive (-/-)
– Water
– Nutrients (ex. Nitrogen)
– Sunlight
• Commensalistic (+/0)
– Plant secretions
•
Facilitative (+/+)
– Soil Improvement
– Structure
– Deter Predators
– Attract Pollinators
Competition: An Argument For
• There is an increase in nutrients and water
infiltration beneath plant canopy, suggesting
an increase in the number of forbs in grass
clumps
Commensalism: An Argument for
• C4 Photosynthesis
in Blue and Black
Grama suggests
possible C3
photosynthesis in
forbs
Facilitation: An Argument For
• There may be nutrient retention by forbs
– Decreases nutrient leaching (benefits the
grasses)
The Question
• What type of relationship?
– Competition (work against each other)
– Commensalism (one works for the other)
– Facilitation (work with each other)
Methods
• Quarter meter plots- randomly tossed in Black Grama,
Blue Grama, and Ranchland
– Veg Surveys:
•
•
•
•
Grass Area - quad
Forb Type
Forb Area
Forb Position
Results
Plant Cover
1600
1400
1362.688
1240
Cover (sq cm)
1200
962.56375
1000
Grass
800
595.395
600
400
200
0
Ungrazed
Grazed
Total
Results
Total Num ber of Species in Black v Blue
Gram a
Total Num ber of Individuals in Black v
Blue Gram a
18
160
149
16
16
140
14
120
12
12
100
10
9
Black
8
8
6
Black
80
Blue
7
60
5
Blue
51
50
40
4
21
13
20
2
0
28
0
Edge
Clump
Bare
Edge
Clump
Bare
Total Num ber of Individuals in Grazed v
Ungrazed
Total Num ber of Species in Grazed v
Ungrazed
15
16
600
14
510
14
500
12
400
10
8
7
Grazed
7
Grazed
300
Ungrazed
Ungrazed
6
200
4
2
126
2
100
2
38
33
4
0
13
0
Edge
Clump
Bare
Edge
Clump
Bare
Results
Methods
• Grasses were clipped in order to determine whether
short- term grazing had an effect on forb growth
– 10 cm radius
– Clipped to the base
– 2 species:
caesalpenia drepanocarpa
macheranthera pinnatifida
Results
Results
Synopsis
• There is no strong correlation between
grazing and forb growth in a season, but
long term data shows that there is an
increase in forb number when the grass
cover decreases
References
• Callaway, R., Walker, L.; Ecology (1997); Competition and
Facilitation: A Synthetic Approach to Interactions in Plant
Communities; pp.1958-65
• Kieft, T., White, C., Loftin, S., Aguilar, R., Craig, J., Skaar, D. 1998.
Temporal Dynamics in Soil Carbon and Nitrogen Resources at a
Grassland- Shrubland Ecotone. Ecosystems. p 671-683
• Bhark, E., Small E. 2003. Association between Plant Canopies and
the Spatial Patterns of Infiltration in Shrubland and Grassland of the
Chihuahuan Desert, New Mexico. Ecosystems. p 185-196
Thanks to…
• Sevilleta LTER
• Fish and Wildlife
• Scott Collins
• Jennifer Johnson
• The Friggens
• Michell
With help from…
• Fred Whiteman
• Andrew Rominger
• Caitlin Smith
• Brenda Nieto
• Alex Benhumea
• Tierney Adamson