Nitrogen, Phosphorus, and Soil Respiration discusses how nutrient additions can affect soil respiration in forest soils. Specifically, the study measured soil respiration in 13 forest stands of 3 different age classes that received treatments of nitrogen, phosphorus, or nitrogen and phosphorus combined. The results showed that soil respiration was affected by forest age and nitrogen addition, but not phosphorus addition or any interactions between nutrients. Next steps include collecting a second year of data, comparing soil respiration to fine root biomass, and adding year and soil temperature to statistical models.

1. Nitrogen, Phosphorus, and
Soil Respiration
By Shiyi Li
Advisor: Tim Fahey
Cornell University

2. Soil Respiration
-- A major flux of carbon to the atmosphere
Source: http://www.wrsc.org/attach_image/global-carbon-cycle

3. Components of soil respiration:
 Microbial respiration ~60%
 Root respiration ~40%

4. Nutrient additions to forest soils can
affect soil respiration.
 Well known that N addition suppresses
microbial respiration
 Effects of P and N+P not well known
 Forest age might influence nutrient effect

5.  13 Stands, 3 Age
classes
 4 measurements
Jun – Aug, 2016
 7 respiration collars
/treatment
Measuring soil respiration
N P
N + P C

6. Measuring soil respiration using Licor 8100

7. 2016 Soil Respiration (μmol CO2/m2/second)
 Age effect
 N effect
(p= 0.012)
❌ P effect
(p= 0.370)
❌ Interactions

8. Treatment starts

9. Treatment starts

10. Treatment starts

11. Next step:
 Collecting 2017 data
 Compare soil respiration and fine root biomass
 Add year and soil temperature to stat models

12. Thank you!!