1. SUNY-ESF Kikang Bae (kbae02@syr.edu)
Still waiting for fertilization effects on soil respiration and root respiration
SUNY-ESF
Kikang Bae

2. Introduction
Soil respiration is a major flux of carbon to the atmosphere.
Nutrient additions to forest soils can affect soil respiration.
The global carbon cycle

3. aboveground respiration root + microbial respiration
Introduction
Ways nutrient addition affects soil respiration:
Altering root activity
Altering microbial activity
Change above- and below- ground carbon production
Soil respiration will increase or decrease after nutrient addition?
photosynthesis
aboveground respiration
CO2
CO2
soil respiration
root + microbial respiration

4. Objectives
To determine effects of nutrient additions on soil respiration and root respiration between forest ages
To understand which component (root or microbial) causes changing soil respiration, if there is a change at all
To know which nutrients (N, P, N+P) have the greatest effect on soil respiration in our stands.

5. (root/microbial respiration)
Hypothesis
Adding nutrients
(N, P, N+P)
Soil respiration
(root/microbial respiration)
Forest age

6. Soil respiration before fertilization
Hypothesis
Adding nutrients
(N, P, N+P)
Soil respiration
(root/microbial respiration)
Annual soil respiration (gC/m2)
Bartlett
Hubbard Brook
Jeffers Brook
Age: P = 0.11
Site: P = 0.02
Soil respiration before fertilization
(09’-11’)

7. Hypothesis Soil respiration Adding nutrients
(N, P, N+P)
Soil respiration
(root/microbial respiration)
Forest age
Soil respiration more
Young: N+P > N > P > Control
Old: N+P > P > N > Control

8. Study sites Bartlett Experimental Forest (BEF)
Hubbard Brook (HB, WS 101)
Jeffers Brook (JB)
Intensive
trenching
Young (20~22 yrs)
Middle (30~40 yrs)
Old (77~127 yrs)
Bartlett C1 C2 C3 C4 C5 C6
Jeffers Brook
Mid
Hubbard Brook C7 C8 C9
Old

9. Methods Soil respiration: Chamber (Licor 8100).
Root respiration (Soil respiration – without live root respiration): Trenching

10. Results (Fertilization on soil respiration)
Fertilization start
Fertilization start
P < 0.001

11. P = 0.006 Fertilization start Fertilization start Fertilization start

12. Fertilization start
Fertilization start
Fertilization start
Fertilization start

13. Results (Root contribution on soil respiration)
Soil respiration – without live root respiration

14. Results (Fertilization on trenching)
Fertilization start
Fertilization start

15. Fertilization start
Fertilization start
Fertilization start

16. Summary Soil respiration No change (except C9 and HB mid)
Root respiration No change
Adding nutrients
(N, P, N+P)
Regardless of nutrients (N, P, N+P) and forest age
Soil respiration No change

17. Conclusion
There was little evidence of fertilization effects on soil respiration after 2 years nutrient addition.

18. Future plans Keep measuring soil respiration.
How do N, P, and N+P additions affect root growth?
good
May June

19. Acknowledge
Ruth Yanai
Tim Fahey
Melany Fisk

20. Acknowledge

21. Thank you...