Transcript The effects of leaf litter species diversity on decomposition in a

The effects of leaf litter species diversity on decomposition in
a forested watershed
Becky A. Ball, Mark A. Bradford, David C. Coleman, Mark D. Hunter, John S. Kominoski, Catherine M. Pringle
Institute of Ecology, University of Georgia, Athens, GA 30602
Results:
Introduction:
There is currently much debate about the effect of species diversity on
ecosystem functions, and many theories exist about the relationship
between the two. For decomposition, no clear patterns have emerged
(see Hättenschwiler et al. 2005, Gartner and Cardon 2004), though an
idiosyncratic relationship is commonly found. Such results likely arise due to
the way in which diversity is defined. Species diversity can be defined by
species richness (the number of species involved) and composition (the
identity of species involved). Composition can be further defined as
having additive effects (where a mixture reflects the average of the
species involved) and non-additive effects (where mixture behaves
differently than would be expected by the average). In order to separate
richness and composition when researching species diversity, a full
factorial design is necessary. This project utilizes a full factorial design to
determine the effects of leaf litter species diversity on decomposition and
nutrient cycling in a forested riparian zone in the southern Appalachians.
Decay rate:
0.0013
0.0012
k day
-1
0.0011
0.001
0.0009
0.0008
0.0007
0.0006
1
2
P = 0.61
4
Species Richness
61
Mass loss:
3
Richness P = 0.61
Composition P = 0.98
60
*
*
*
% AFDM Remaining
59
58
57
present
56
absent
55
54
53
52
51
L
A
Q
R
Species
90
Chemistry:
Richness P = 0.31
Richness * time P = 0.97
80
Composition P = 0.00
Composition * time P = 0.46
50
70
C:N Ratio
60
1 sp
50
2 spp
40
3 spp
4 spp
45
together
not tog
40
30
20
35
10
LAQ
0
0
6
12
18
24
30
1.40
*
LAR
Composition
Time (months)
0.07
Richness P = 0.41
Composition P = 0.00
*
Richness P = 0.73
Composition P = 0.04
1.30
Lower Ball Creek, November 2003
*
1.20
not tog
LAQ
AQR
Combination
Acknowledgements:
•NSF Award #0218001
•Coweeta LTER
•Institute of Ecology Graduate Students
and undergraduate work-study students
•Institute of Ecology Analytical Lab
•Dr. Keller Suberkropp, University of Alabama
*
together
not tog
0.05
1.10
1.00
Literature Cited:
Hättenschwiler et al. 2005. Ann. Rev. Ecol, Evol and Syst. 36:191-218.
Gartner and Cardon. 2004. Oikos 104:230-246.
0.06
together
%P
%N
Methods:
• Site: Lower Ball Creek, Coweeta Hydrologic Lab, Otto, NC
• Leaf Species: Liriodendron tulipifera (L), Acer rubrum(A), Quercus prinus
(Q), Rhododendron maximum(R)
L
LA
LAQ
LAQR
A
LQ
LAR
Q
LR
LQR
R
AQ
AQR
AR
QR
• Litterbag method to study decomposition over 3 years
J. Kominoski
• Assays:
•Fiber
• AFDM (k rate)
-Cellulose
• C:N:P
-Hemicellulose
• Phenolics
-Lignin
-Total phenolics
•Fauna
-Condensed tannins
-Bacteria (DAPI)
-Hydrolysable tannins
-Fungi (Ergosterol)
-Nematodes
-Arthropods
•Full factorial ANOVA explores effect of composition and
richness independent of the presence/absence of each
species
*
*
C:N Ratio
Questions:
1.
Is there a significant effect of species richness on decomposition?
2.
Is there an effect of species composition on decomposition? If so, is it
additive or non-additive?
3.
What does this tell us about nutrient cycling?
0.04
LAQ
AQR
Combination
Discussion:
•Mass Loss
•No significant effect of richness on mass loss
•No significant non-additive effect of composition on mass loss
•There are additive interactions based on the presence or absence
of certain species
•Chemistry
• No significant effect of richness on chemical properties of litter
• It is composition for which we see significant effects, being nonadditive for the nutrients N and P.
•Implications
•There are possible effects of litter diversity (through composition) on
nutrient movement, both additively and non-additively.
•Species identity has a significant impact in this forested system.