Effects of Simulated MPB on Hydrology and Post-attack Vegetation & Below-ground Dynamics

Transcription

1 Effects of Simulated MPB on Hydrology and Post-attack Vegetation & Below-ground Dynamics Principal investigators: Uldis Silins and Ellen Macdonald Ph.D. projects: Anne McIntosh and Pablo Piña Lead field technician: Pete Presant

2 Time? Relative impact

3 MPB - Unique disturbance agent Larger & older trees selectively killed but remain standing (vs logging) needles can remain 3-5 yrs+ Understory & soil layers not directly affected (vs logging or fire) Return of nonvolatile nutrients to the soil & response of vegetation production are slower (vs stand-replacing fire) 3

4 Broad research questions How much extra water is produced after different levels of red attack? (Pablo Piña) What are the early trajectories of post-attack vegetation and below-ground responses after different levels of red attack? (Anne McIntosh)

5 Approach & treatments Don t wait for MPB (issue of control ; B.C.) Simulate MPB attack variable density herbicide treatment Control (untreated) Simulated MPB attack (50% overstory kill) Simulated MPB attack (100% overstory kill) Clearcut - harvested to simulate salvage logging management 5

6 2.2 ha x ha x 2 1 year pre-treatment measurements 2 years post-treatment measurements 12 stands Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Au - instrumentation Pre-Treatment year Post-Treatment Year 1 Post-Treatment Year 2

7 Study area & design Pure pine ~ 120 yrs Medium site index m height Process studies Water balance - before-after: treatment-control Before After Treatment Control Understory vegetation - replicated (repeated measures)

8 Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Au - instrumentation Pre-Treatment year Post-Treatment Year 1 Post-Treatment Year 2

9 Glyphosate late June 09 Harvest July Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Au - instrumentation Pre-Treatment year Post-Treatment Year 1 Post-Treatment Year 2

10 Canopy regulated environmental factors Air temperature Understory light, air temperature, humidity, wind, etc. Vapor pressure deficit Wind Understory microclimate (compared to canopy) Air temperature (11 % lower, 1-2 o C) Moisture demand (14 % lower) Wind (51 % lower)

11 Canopy regulated environmental factors Air temperature Pre-treatment Post-treatment Understory light, air temperature, humidity, wind, etc. Vapor pressure deficit Change in understory microclimate m ht) Wind Air temperature - Tiny increase Moisture demand small/moderate increase Wind large increase BATC powerful approach to document changes

12 Post-attack hydrologic response Pablo Pina, PhD Student How much extra water is produced after different levels of red attack? 1. Changes in overstory rainfall interception 2. Changes individual tree & stand level transpiration - Can surviving trees compensate (use more water) 3. Changes in forest floor and soil moisture storage 4. Changes in water table level, groundwater

13 Vertical water balance framework Gross precipitation + Evaporative demand Overstory transpiration Canopy interception Forest floor interception Soil moisture storage

14 Rainfall interception Interception = Gross precipitation (Stemflow+Throughfall)-(Throughfall-Forest floor flow) Canopy interception Forest floor interception Overstory transpiration Canopy interception Forest floor interception Soil moisture storage

15 Canopy interception 6 m Stemflow N =3 Throughfall N= 4 Gross precipitation

16 Canopy storage capacity (S) = 8.1 mm Interception loss (mm) Threshold Interception loss Predicted Storm (mm)

17 Forest floor interception 0.5 m Monitoring quadrats N =4 Forest floor quadrat 0.5 m

18 Post-treatment forest floor seasonal weight trends 12 Gross Precipitation (mm) 100 kill 50 kill Clearcut Control Harvested Forest Floor Weight (Kg) Forest Floor Recharge (mm) Julian Day

19 Forest floor water holding capacity Water holding capacity (mm) Storage opportunity (mm) Threshold ~8.5 mm

20 Storm frequency distribution based on rainfall intensity Threshold Storm frequency < >36 (mm)

21 Overstory transpiration Overstory transpiration Canopy interception N = 7 Forest floor interception Soil moisture storage

22 mm/day Pre-treatment Hourly transpiration 6 5 Post-treatment 100% Kill 50% Kill Control mm/day

23 Soil moisture storage Spot measurements soil moisture (TDR) Overstory transpiration Canopy interception Time continuous soil moisture (WCR) Forest floor interception Soil moisture storage

24 Soil moisture at the Control plot 20 cm 40 cm 60 cm Soil moisture storage (mm) Spring melt recharge

25 Soil Moisture at 20 cm depth Forest Floor Recharge Control 100 Kill Clearcut 50 Kill Soil Volumetric Water Content Spring melt recharge Year Forest Floor Recharge (mm)

26 What will happen when the MPB kills the trees? Precipitation Normals Site Data 425 mm 75% of annual gross precipitation) 80 mm Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

27 Conclusions: Overstory transpiration Canopy interception During the growing season: Canopy interception 49% of Precip Forest floor interception could be as high as canopy interception An average tree transpires 5.5 liters/day = > 0.7 liters/m 2 day Transpiration could be 41% of precipitation Understory evaporation? Forest floor interception Soil moisture storage Soil moisture recharge is mainly driven by spring snowmelt

28 Post-attack vegetation & below-ground responses Anne McIntosh, PhD Student What are the early trajectories of post-attack vegetation and below-ground responses after different levels of red attack?

29 Understory Overstory Belowground

30 Understory Overstory? MPB Belowground

31 MPB as a disturbance agent Larger & older trees selectively killed but remain standing (vs logging) Understory & soil layers not directly affected (vs logging or fire) Return of nonvolatile nutrients to the soil & response of vegetation production are slower (vs stand-replacing fire) OUTSIDE HISTORICAL RANGE: HOW WILL STANDS IN AB RESPOND?

32 Post-attack vegetation & below-ground response objectives What are the early trajectories of post-attack vegetation and below-ground responses after different levels of red attack? 1. Changes in overstory forest structure 2. Changes in understory plant community composition (shrubs, seedlings, plants (herbs, grasses, bryophytes) 3. Recruitment of downed woody debris (DWD) 4. Changes in below-ground processes (nutrient availability, microbial community, decomposition)

33 Objective 1: Overstory Characterize the overstory forest structure (0.02 ha plots) Species Live status Dbh Height Crown vigor Cover (hemispherical photos) Measured before (2008) & after (2010) treatment 33

34 Basal area 60 LIVE DEAD 50 Basal area (m 2 /ha) %kill 50%kill Control Salvage Treatment * Post-treatment will be measured in 2010

35 Trees per hectare 2500 LIVE DEAD 2000 Trees per Hectare %kill 50%kill Control Salvage Treatment * Post-treatment will be measured in

36 Mean DBH All Live Dead Mean dbh (cm) %kill 50%kill Control Salvage Treatment * Post-treatment will be measured in

37 Objective 2: Understory Quantify differences in the understory plant community composition Seedlings/Saplings (pine) Advanced regeneration? MINIMAL Germination study (future regeneration potential) Plants (shrubs, forbs, graminoids, bryophytes, lichens) Richness Abundance (% cover) by species Basal area (large shrubs, e.g., alder)

38 Germination study (2010) What is the regeneration potential of these stands after MPB? Quadrats on 5 substrates sowed with seed: LFH < 2.5 cm LFH > 2.5 cm Mineral soil Moss Dead wood (decay class 4-5) Monitor germination weekly

39 Understory richness Mean Richness by Stand %kill 50%kill Control Salvage Treatment 39

40 Understory cover ALDER FERN BRYOPHYTE GRASS SHRUB HERB 120 Cover (%) Kill 50Kill Control Salvage Treatment by Year

41 Understory cover: post-treatment (2009) ALDER FERN BRYOPHYTE GRASS SHRUB HERB 120 Cover (%) a a a b 100%kill 50%kill Control Salvage Treatment

42 Objective 3: Downed woody debris Quantify DWD Transects: biomass estimates (Megagrams/ha) 42

43 DWD biomass Down Woody Debris (Megagrams/ha) %kill 50%kill Control Salvage Treatment

44 Objective 4: Below-Ground Quantify differences in below-ground attributes Decomposition (cellulose paper in mesh bags) ph Microbial biochemical activity & biomass Community-level physiological profiles (CLPP) Phospholipid fatty acid (PLFA) analysis Nutrient availability (PRS probes) Soil moisture (TDR) 44

45 Decomposition Mass loss (%) %kill 50%kill Control Salvage Treatment 45

46 ph ph %kill 50%kill Control Salvage Treatment 46

47 Total Nitrogen %kill 50%kill Control Salvage Treatment 47 Total N (NO3 - and NH4 + ) Supply Rate (micrograms/10cm 2 /summer burial)

48 NO %kill 50%kill Control Salvage 48 Treatment N (NO3- ) Supply Rate (micrograms/10cm 2 /summer burial)

49 NH %kill 50%kill Control Salvage Treatment 49 N (NH4+ ) Supply Rate (micrograms/10cm 2 /summer burial)

50 Understory Overstory MPB (short-term) Belowground

51 Recap & the future

52 Project timeline Fall 2007 May 2008: site selection, plot layout, instrumentation June : pre-treatment data collection June 2009 July 2009: treatment application June : 1 st post-treatment year data collection June : 2 nd post-treatment year data collection June 2011 Mar 2012: analysis and write-up Subsequent data collection?

53 What information will we have? Characterize water balance of these forests: Where the water is/goes How much water do they use? Characterize forest structure, vegetation, below-ground Relationships: canopy, understory vegetation, soils Potential for tree regeneration What happens when the trees die and stay standing?

54 Short-term responses of lodgepole pine forests to this unique disturbance Transpiration Interception Future forest development Soil water Soil nutrients Understory cover Species-specific responses Light? Below-ground communities Below-ground processes Understory community change Recover water balance?

55 Short-term responses of lodgepole pine forests to this unique disturbance Effects of gradient of disturbance: Water yield? Vegetation change? Recovery of water balance? Tree regeneration? Future forest development? LONGER TERM RESPONSES.?

56 Support for the work Foothills Research Institute FRIAA / AB SRD West Fraser Timber Co. Ltd. NSERC CONACYT Milo Mihajlovich Field Assistants Thank you for listening For further information: uldis.silins at ales.ualberta.ca ellen.macdonald at ales.ualberta.ca ppina at ualberta.ca amcintos at ualberta.ca