umbs forest carbon cycle research program

UMBS ForestCarbon CycleResearch Program

Forecasting Carbon Storage in Aging Forests of the Upper Mid-West:

New Insights From the Forest Accelerated Succession ExperimenT (FASET)

Peter S. Curtis, Christopher M. Gough, Lucas E. Nave, Brady Hardiman, Gil Bohrer, Abby Halperin,

Christoph S. Vogel, Kyle Maurer, Knute Nadelhoffer, James Le Moine, Jed Sparks

Ohio State University, University of Michigan, Virginia Commonwealth University, Cornell University

UMBS ForestCarbon CycleResearch Program

Current Status of the Great Lakes Forests They cover about half of their original area. They bear little structural or compositional resemblance to the original forest. They are mostly young and homogeneous.

www.nrs.fs.fed.us

Forest age (years) WE ARE HERE

EVEN-AGED(mostly aspen)

UNEVEN-AGED(maple, oak, pine)

ASPEN MORTALITYnatural senescence, pathogens, insects

Succession

Many Stands Are Now at an Ecological Transition, Between Young and Potentially Old Community Types

Northern Great Lakes: 643,000 ha (13% all timberland)

Northern Superior Uplands: 104,000 ha (9% all timberland)

Northern Minnesota: 369,000 ha (10% all timberland)

Potentially Old Timberland (80-120 yrs) in the Lakes States

Southern Superior Uplands: 830,000 ha (16% all timberland)

Eastern Broadleaf Forest: 672,000 ha (19% all timberland)

All timberland: 19,494,000 haPotentially old: 2,747,000 ha (14%)Old: 464,000 ha (2%) (after Schmidt et al., 1996)

UMBS ForestCarbon CycleResearch Program

Gough et al. (2008)Luyssaert et al. (2008)

Although some forests accumulate C for centuries, the mechanisms behind sustained rates of C storage in aging deciduous forests have not been identified.

UMBS ForestCarbon CycleResearch Program

Figure 1. Conceptual diagram of forest age and production. Recent data have called into question the extent of productivity decline in mature-to-senescing stands. Most ecosystem models are poorly equipped to simulate forests in this older age range.

Conventional theory suggests declining productivity and C storage in over-mature stands. Increasing biotic and structural complexity with age could alter this trajectory.

The UMBS Forest Carbon Cycle Research Program

• Peter Curtis, Ohio State Univ.• Gil Bohrer, Ohio State Univ.• Chris Gough, Virginia Commonwealth Univ.• Chris Vogel, Univ. Michigan• Knute Nadelhoffer, Univ. Michigan• Danilo Dragoni, Indiana Univ.

This research is supported by the Office of Science, U.S. Department of Energy, through the Midwestern Regional Center of the National Institute for Global Environmental Change, and the National Institute for Climate Change Research.

The UMBS landscape is a mosaic of forest stands varying in age and disturbance history

Sampling transects

Burn chrono-sequence

UMBS ForestCarbon CycleResearch Program

More Diverse Forest Plots Are More Resilient to Carbon Storage Declines With Age

Gough et al. (2010)

UMBS ForestCarbon CycleResearch Program

Older Plots That Are More Structurally Complex Have Higher Wood Production

We measure canopy complexity (rugosity,r ) with a portable canopy lidar system.

Hardiman et al. (in review)

Examples of canopies with Low (A), Medium (B), and High (C) rugosity but with equivalent Leaf Area Index (LAI). Canopy features are marked with roman numerals.

UMBS ForestCarbon CycleResearch Program

Relationship Between Canopy Complexity, Stand Age, and Wood NPP

Rugosity reaches a maximum value at 70-80 yrs. Wood NPP is exponentially related to rugosity. Rugosity is largely independent of LAI and is more strongly correlated with wood NPP.

UMBS ForestCarbon CycleResearch Program

The Forest Accelerated Succession ExperimenT (FASET)

Conceptual model of NEP before, during, and following aspen and birch mortality. N availability will have an important effect on final NEP.

Year1998

20002002

20042006

20082010

20122014

20162018

NE

P (M

g C

ha-

1 yr

-1)

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5Hypothetical NEPHypothetical N availability

Girdling

succession

climateA

B

C

climate reco

verydisturbance

+

-

N a

vaila

ble

for p

lant

gro

wth

UMBS ForestCarbon CycleResearch Program

Increasing Aspen and Birch Mortality: Accelerated fine root turnover Reduced soil respiration Prompted the redistribution of N from the foliage of early to later successional species.

Effects on fine root NSC and turnover.

Effects on soil respiration, temperature, and moisture.

UMBS ForestCarbon CycleResearch Program

Leaf N content decreased in senescing (EM) aspen but increased in neighboring (AM) maple. Leaf δ15N increased significantly in neighboring maple and oak.

Effects on leaf %N in aspen, maple, and oak

Effects on leaf δ15N in aspen, maple, and oak

UMBS ForestCarbon CycleResearch Program

Effects on Ion Exchange Resin Bag (IERB) recoverable NH4 and NO3

Effects on hydrologic (left) and gaseous (right) N losses.

Soil N availability increased with increasing aspen/birch mortality. Hydrological and gaseous N losses were small, but measureable.

UMBS ForestCarbon CycleResearch Program

Growing season NEE was reduced as aspen/birch mortality progressed. This was due to lower GPP in the FASET plot.

Mortality effects on growing season (top) and dormant season (bottom) NEE.

Year1998

20002002

20042006

20082010

20122014

20162018

NE

P (M

g C

ha-

1 yr

-1)

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5Hypothetical NEPHypothetical N availability

Girdling

succession

climateA

B

C

climate reco

verydisturbance

+

-

N a

vaila

ble

for p

lant

gro

wth

UMBS ForestCarbon CycleResearch Program

Increased N availability and canopy complexity work in concert to support increases in production as these forests age Likely mechanisms are improved light capture and light use efficiency. These results provide new insights into the mechanisms by which deciduous forests maintain high rates of production into late succession They suggest that forests of the upper Mid-West will continue to be important C sinks for decades into the future.

Conclusions