Detritus Quality

1
Detritus Quality Temperature Moisture Soil
Texture
2
Detritus Quality Temperature Moisture Soil
Texture
3
Relationship between litter ligninN and
decomposition
Mellillo et al. 1982
4

• Focus has been on mass loss of aboveground
  litter.

• Confounded by variation in leaf morphology or
  other aspects of leaf chemistry.

• Where do decomposition products end up?

5
Proposed mechanisms for soil carbon formation
Lignin Based
Non-lignin based
Stevenson 1994
6
Canopy
CO2
Total Belowground C Allocation
Litterfall
?CL
Litter Layer
Mineral soil surface
Roots ?CR
Soil Carbon
?CS

Rhizosphere
7
Faster carbon decomposition in pine soils
More carbon in aspen soils
Aspen
Pine
mg C / g soil C
Giardina et al. 2001
8
Paired plots measured 70 years following
afforestation with red pine or old-field
succession to northern hardwoods
Mineral soil
Forest Floor
Live Shoot
Live Root
Total System
Gahagan et al. In Prep
9
Greenhouse mesocosms of trembling aspen
Detritus from C3 Aspen d13C 29
Soil from C4 Konza grasses d13C 15
Following the fate of carbon from plant to soil
to atmosphere.
10
Aspen stem tissue chemistry
Hu et al. 1998
11
Regularly measured plant height and the length
and width of each leaf. Photosynthesis light
response curves, soil CO2 efflux and 13CO212CO2
of efflux
12
Modification reduced total biomass C and biomass
partitioning to roots.
b
b
Aspen with high S/G (93) had the lowest total C
mass and R to S. Control plants had 15 more
root biomass C than low lignin lines (23 141)
and 50 root C than aspen with high S/G ratios
(93)
b
b
LL-HC
LL-NC
High S/G
Control
Hancock et al. In Review
Distribution of biomass C in aboveground and
belowground pools
13
Modifications reduced soil carbon formation
Control aspen (271) accumulated 40 more new soil
carbon than low lignin aspen (23 141). Control
aspen (271) accumulated 70 more new soil C than
high S/G aspen (93).
Hancock et al. In Review
14
Kansas silt loam
Colorado sandy loam
Texas clay loam
15
O3 reduces C formation under elevated CO2
Loya et al. 2003
16
Leaf litter N Control 15.3 mg g-1 High CO2 13.1
mg g-1
Leaf litterfall N Control 3.52 g N m-2 High CO2
3.96 g N m-2
Liu et al. 2005
Giardina et al. In Review
17
Input of decay resistant compounds
Birch
Giardina et al. In Review
18
Birch stands at Aspen FACE
Elevated CO2 increases TBCA
Giardina et al. 2005
19
Fissore et al. In Prep
20
C loss at 10OC and 30OC (MAT)
Fissore et al. In Prep
21
Total Belowground C Allocation increases with MAT

TBCA 355 39MAT R2 0.49
Q10 1.6
Giardina et al. 2005