Effects of Experimental Burning and Thinning on Soil Respiration and Belowground Characteristics

1. Effects of Experimental Burning and Thinning on Soil Respiration and Belowground Characteristics Soung-Ryoul Ryu1, Amy Concilio1, Jiquan Chen1, Deborah Neher1, Siyan Ma1 and Malcolm North2 1Department of EEES, University of Toledo, Toledo, OH2Department of Environmental Horticulture, University of California-Davis, Davis, CA

2. Objectives • Evaluate the effects of prescribed burning and thinning on soil chemistry, microclimate, root biomass, and soil respiration within mixed coniferous forest • Evaluate the primary factors affecting root biomass and soil respiration rate under burning and thinning treatments.

3. Site Description • Teakettle Experimental Forest • 1300ha of area, located in Sierra National Forest on the west side of the Sierra Nevada range of California. • Altitude: 1980 ~ 2590 m • Precipitation: 1250mm/year, mostly in the form of snow • Mean air temperature: 1°C(January ) and 14.5°C(July)

4. Plot Preparation • Eighteen plots (4 ha each) were prepared using variogram and cluster analysis (North et al. 2002). • California spotted owl (CASPO) thinning, and shelterwood thinning were applied between August 2000 and Summer of 2001 • Prescribed burning followed November 2001 • Transects (1m spaced) developed at • Burn-CASPO (BC), Burn-Shelterwood (BS), Burn only (BN), Unburn-CASPO (UC), Unburn-Shelterwood (US), and Control (UN) plots

5. Field Measurement • Soil respiration rate (SRR; gCO2 hr-1 m-2): a portable infrared gas analyzer (EGM-2 Environmental Gas Monitor, PP Systems, UK) • Soil temperature at 10cm depth (Ts; ˚C): using a digital thermometer simultaneously with SRR measurement. • Soil moisture (Ms; %): Time Domain Reflectometry (TDR) within 0~10cm depth in mineral soil. • Litter depth (LD) • Measured at least every other week during the growing season of 2002

6. Field Measurement • Total nitrogen (TN) and total carbon (TC) content in soil: using CN analyzer (Carlo Erba NA 1500 Series 2) • pH: soil:H2O = 1:2 • Fine root biomass (<2mm; FR) and coarse root biomass (>2mm; CR) • Soil samples were collected during June 25 to July 3, 2002

7. Source DF SS MS F Value Pr > F TN (%) burn 1 0.01 0.01 9.11 0.0028 thin 2 0.00 0.00 1.06 0.3475 burn*thin 2 0.00 0.00 1.54 0.2163 TC (%) burn 1 0.02 0.02 1.24 0.2662 thin 2 0.10 0.05 2.75 0.0655 burn*thin 2 0.09 0.05 2.56 0.0787 CN burn 1 3.77 3.77 23.97 <.0001 thin 2 4.13 2.07 13.14 <.0001 burn*thin 2 0.45 0.22 1.43 0.2416 pH burn 1 0.02 0.02 8.46 0.0039 thin 2 0.12 0.06 24.16 <.0001 burn*thin 2 0.04 0.02 6.95 0.0011 Effect of burning and thinning on the soil chemistry

8. Source DF SS MS F Value Pr > F SRR (gCO2 hr-1 m-2) burn 1 1.06 1.06 99.50 <.0001 thin 2 0.13 0.07 6.34 0.002 burn*thin 2 0.02 0.01 0.96 0.3841 Ts (˚C) burn 1 0.27 0.27 118.58 <.0001 thin 2 0.85 0.43 190.90 <.0001 burn*thin 2 0.07 0.04 16.45 <.0001 Ms (%) burn 1 55.42 55.42 9.97 0.0018 thin 2 95.35 47.67 8.58 0.0002 burn*thin 2 0.22 0.11 0.02 0.9805 LD (cm) burn 1 3664.78 3664.78 160.18 <.0001 thin 2 97.84 48.92 2.14 0.1197 burn*thin 2 171.04 85.52 3.74 0.0249 Effect of burning and thinning on the microclimate

9. Source DF SS MS F Value Pr > F FR010 burn 1 17.89 17.89 9.66 0.0026 thin 2 11.53 5.77 3.11 0.0495 burn*thin 2 6.06 3.03 1.64 0.2008 FR1020 burn 1 4.89 4.89 5.22 0.0248 thin 2 13.54 6.77 7.22 0.0013 burn*thin 2 8.80 4.40 4.69 0.0116 FR burn 1 43.91 43.91 12.90 0.0006 thin 2 49.68 24.84 7.30 0.0012 burn*thin 2 18.01 9.00 2.64 0.0769 CR010 burn 1 1.06 1.06 2.54 0.1144 thin 2 0.33 0.17 0.40 0.6728 burn*thin 2 0.36 0.18 0.43 0.6504 CR1020 burn 1 3.76 3.76 1.70 0.1955 thin 2 15.49 7.74 3.50 0.0344 burn*thin 2 10.79 5.40 2.44 0.093 CR burn 1 7.11 7.11 2.77 0.0999 thin 2 11.39 5.69 2.22 0.1152 burn*thin 2 9.06 4.53 1.76 0.1777 Effect of burning and thinning on the Root Biomass

10. TN TC CN pH (box-whisker with Anova) ab ab a ab b ab ab ab a ab ab b c b ab ab ab a a a b a a a

11. SRR Ms Ts LD ab a bc bc ab c c c c ab a b a a b b a c c c c b a ab

12. 0~10 cm FR CR 010 1020 b b ab b ab a a a a a a a 10~20 cm c bc abc bc a ab b ab ab b ab a

13. Correlation TN TC pH Ts Ms LD BC 0.86 0.78 0.28 0.23 -0.50 0.44 BS 0.09 0.14 0.06 -0.11 -0.18 -0.48 BN -0.15 -0.17 0.37 -0.40 0.26 -0.15 UC 0.66 0.17 0.68 -0.25 -1.15 -0.49 US -0.09 0.09 0.30 0.80 0.44 -0.25 UN 0.11 0.33 -0.33 0.06 -0.06 0.40 Path Analysis on FR biomass at 0~10 cm

14. Path Analysis – SRR

15. Conclusions • Fine root biomass at 0~10cm was affected more by burning whereas fine root biomass at 10~20cm were more affected by thinning • Factors affecting fine root biomass can vary by intensity of thinning as well as the type of management treatments • SRR was affected most by root biomass under burning + thinning treatment, while by temperature at thinning only and by LD at burning only.

16. Acknowledgements • Teakettle Experimental Forest • Forest Service • Joint Fire Science Program • LEES Lab, Dept of EEES, University of Toledo

17. Questions?

18. Soil respiration rate (SRR; gCO2 hr-1 m-2): a portable infrared gas analyzer (EGM-2 Environmental Gas Monitor, PP Systems, UK) with a SRC-1 Soil Respiration Chamber (PP Systems, UK). • Soil temperature at 10cm depth (Ts; ˚C): using a digital thermometer (Taylor Digital Max/Min, Forestry Suppliers, Inc, USA) simultaneously with SRR measurement. • Soil moisture (Ms; %): Time Domain Reflectometry (TDR, model 6050XI. Soil Moisture Equipment Corp., Santa Barbara, California, USA) within 0~10cm depth in mineral soil.

19. Extra data • This forest has three major patches, • closed canopy by mixed conifer (CC), • Ceanothus cordulatus Kellogg. shrub dominant areas (CECO) • open canopy (OC). • CC, OC, and CECO occupy the 67.7, 13.4, and 4.7% of the entire study forest respectively (North et al. 2002). • Major conifer species includes Abies concolor Lindl. ex Hildebr, A. magnifica A. Murr, Pinus lambertiana Douglas, P. jefreyi Grev. and Balf, and Calocedrus decurrens (Torr.) Florin (North et al. 2002). • Soils are classified as Xerumbrepts and Xeropsamments (North et al. 2002).