1 / 21

Main points: Moisture and temperature controls over the season

Main points: Moisture and temperature controls over the season - three ‘regimes’ Nov-March – cold and wet April – October – warm and very dry September rain – warm and wet

hedda-farrell
Download Presentation

Main points: Moisture and temperature controls over the season

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Main points: • Moisture and temperature controls over the season • - three ‘regimes’ Nov-March – cold and wet • April – October – warm and very dry • September rain – warm and wet • Annual respiration balance may depend on the occurrence of warm rains • During the April-October period (summer), roots in the top ~40 cm do not contribute significantly to soil respiration • - very little difference between trenched versus untrenched plots • - no isotopic differences between trenched and untrenched plots • 3. Isotopes show shifts in the importance of different respiration sources • Wetup of litter layer only (experiment) did not show the same response as wetup of plants + litter •  implies that • 4. Diel controls also show shifts with season; when it is wet, temperature is the main control; when it is dry, relative humidity? Is the main control or there is no diel variability (also little surface autotrophic respiration source to drive respiration).

  2. Brown = trenched Green = untrenched Trenching Flux mgC m-2 hr-1 Nov 06 Jan 07 March 07 July 07 Sept 07 May 07

  3. Three ‘regimes of temperature, moisture. Nov-March is cold and humid April- october is dry but warm; one rain event in september stands out as a time when it is wet and warm. Next slide shows fuel rod moisture Data showns are daily averages. Litter Relative Humidity Temperature at 2 cm depth (ºC)

  4. Fuel Rod (water content) Temperature at 2 cm depth (ºC)

  5. Chamber 8 (untrenched) Chamber 5 (trenched) Flux mgC m-2 hr-1 Temperature (2 cm) Temperature (2 cm) Flux mgC m-2 hr-1 Litter relative Humidity Litter relative Humidity

  6. Chamber 7 (untrenched) Chamber 6 (trenched) Flux mgC m-2 hr-1 Temperature (2 cm) Temperature (2 cm) Flux mgC m-2 hr-1 Litter relative Humidity Litter relative Humidity

  7. Chamber 2 (untrenched) Chamber 1 (trenched) Flux mgC m-2 hr-1 Temperature (2 cm) Temperature (2 cm) Flux mgC m-2 hr-1 Litter relative Humidity Litter relative Humidity

  8. Chamber 4 (trenched) Chamber 3 (untrenched) Flux mgC m-2 hr-1 Temperature (2 cm) Temperature (2 cm) Flux mgC m-2 hr-1 Litter relative Humidity Litter relative Humidity

  9. Day 468 -473 Day 500-505 Day 531 - 538

  10. Day 603-607 Day 615-617 Day 640-643

  11. D14C of respired CO2

  12. No difference between trenched/untrenched For 7 of 8 chambers, 14C during the day after wetting was higher than the previous night For chambers 1-4, wetted chambers (2,4) had higher 14C than controls (1,3) regardless of trenching treatment This trend is less obvious for chambers 5,7 (dry) versus 6,8 (wet). D14C T,D T,D T,W T,W U,W U,W U,D U,D T = trenched U = untrenched D = dry W = wetted

More Related