Some Ecological benefits of prairies

Transcription

1 Some Ecological benefits of prairies Diego Steinaker CIEE / ICEE (Canadian Institute of Ecology and Evolution / Institut canadien d écologie et d évolution) University of Regina, Biology. diego.steinaker@uregina.ca

2 Native Grasslands provide Ecosystem Services: Biodiversity: Gene pool reserves (rare species), Stability of primary production, Insect abundance & diversity: pollination and pest control. > forage quality, < livestock methane emission. Efficient Nutrient cycling Water regulation (water-holding capacity, infiltration, water quality improvement) Sustainable beef production (low Saskatchewan PFRA energy input: oil, fertilizers, herbicides) pastures: 728,000 ha Carbon sequestration Store around 150 million tonnes of carbon; Carbon credit is valued at U$S 21/tonne, The carbon in PFRA soils would be worth nearly 3.1 U$S billion.

3 Overgrazing Degraded grassland Land-use changes Conversion Perennial pastures Biodiversity: Gene pool reserves (rare species), Stability of primary production, Insect abundance & diversity: pollination and pest control. > forage quality, < livestock methane emission. Efficient Nutrient cycling Water regulation (water-holding capacity, infiltration, water quality improvement) Sustainable beef production (low energy input: oil, fertilizers, herbicides) Carbon sequestration Annual croplands

4 Land-use changes Overgrazing Degraded grassland Conversion Perennial pastures Annual croplands Loss of ecosystems services Keeping the prairies under public ownership will certainly favor a sustainable use of these ecosystems.

5 Overgrazing NPP, C Soil erosion, fertility

6 Enclosure NPP, C Climate CO 2 Overgrazing NPP, C

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8 STUDY SITES: Northern Great Plains

9 STUDY SITES Alberta Saskatchewan Manitoba Edmonton KINSELLA Regina RMNP Winnipeg Montana GAP North Dakota

10 STUDY SITES GAP Community Pasture, SK Kinsella, AB Saskatchewan Riding Mountain NP, MB North Dakota

11 Methods: Three factors: Temperature: Warming Control (amb. temp) Water: -75% PPT +75% PPT Control (amb. PPT) Defoliation : Light (7.5 cm height) Heavy (2.5 cm height) Control (no defoliation)

12 Experimental Design x 3 sites (AB, SK, MB) +15% Precipitation Heavy Grazing Warming -15% Precipitation Ambient Precipitation Light Defoliation No Defoliation No Warming n = 5

13 Warming Treatment Open-top chambers (OTCs) Transmit visible light, but not infra-red Raise temperature 2-4 o C above ambient Warming Control (amb. temp)

14 Annual temperature increase by the end of the century Temperature projected changes in the 21st century (change between 1980 to 1999 and 2080 to 2099 ) from a multi-model data set (21 global models) and for the A1B scenario (Christensen et al. 2007).

15 Precipitation Treatments PPT Levels: Ambient precipitation (Control) -75% precipitation (Drought) +75% precipitation (Wet season)

16 Defoliation (grazing simulation) Light Heavy No defoliation Defoliation Levels: Light defoliation (7.5 cm height) Heavy defoliation (2.5 cm height) Control (no defoliation)

17 Net Primary Production: Belowground > Aboveground

18 Aspen Forest & Grassland Experimental Plots (University of Regina)

19 NPP (g / m2 / yr) Total Net Primary Production (NPP) Grassland Aspen Forest 90 % 75% Shoots Roots Aboveground: P < Belowground: NS Total: NS Steinaker & Wilson Ecology, 86:

20 NPP (g / m2 / yr) Total Net Primary Production (NPP) Grassland Aspen Forest 90 % 75% Shoots Roots Aboveground: P < Belowground: NS Total: NS

21 Minirhizotron to measure Root Production

22 Root Production (Minirhizotron image sequence) July 1 July 14 5 mm July 28 Aug. 13

23 Root density (cm/im) Grazing enhanced both drought and warming effects. Grazing x Water Grazing x Temperature ns Control *** Drougth *** None Light Heavy Grazing ns Control ns Warming ** None Light Heavy Grazing It is possible to mitigate climate change by managing grazing

24 Root density (cm/image) ns a a b Management difference: 20 % more roots with moderate grazing. 12 No Grazing 10 Light Grazing Heavy Grazing 8 Control Warming We can increase 20 % of belowground C through grazing management. Other studies found % increases in soil C storage (SOM) when grazing management is improved (Conant et al. 2003; Derner and Schuman 2007, Sousa et al 2012)

25 Grazing magnify drought and warming effects. C sequestration Grazing X Climate Primary Productivity Range Management Land management through grazing E.g., Proper stocking rates, Rest-rotation systems, etc.

26 Range Management: grassland productivity, soil organic carbon, C sequestration. 2 Poor condition 3 Good condition NPP, SOC, C It is possible to mitigate climate change by managing grazing

27 Watering site Poor condition Good condition

28 Watering site Distance from the water Percentage of grass use by cattle 500 m 85% 1000 m 60% 1500 m 37% 2000 m 17% 2500 m or > 3% (Anchorena 1998, Sager 2008)

29 Watering site? Grassland replacement. Conversion Poor to condition tame pasture.? Good condition Loss of diversity, C, N, risk of soil erosion, loss of $$

30 Watering site 1 From a continuous? grazing system to a Switchback rotation system. Watering site 2

31 Switchback rotation system. More evenly distribution of livestock grazing pressure. Watering site 1 The rested grassland will improve rangeland condition. Watering site 2

32 Rotational grazing: Allows grasses time to recover and re-grow. Grazing period: Recovery allowed: Short Long Continuous Long Short None

33 Drought > C < C Grazing period: Recovery allowed: Short Long Continuous Long Short None

34 Switchback rotation system. More evenly distribution of livestock grazing pressure. Watering site 1 The rested grassland will improve rangeland condition. Watering site 2

35 Rotation grazing system. Field 1: Grazed June

36 Rotation grazing system. Field 2: Grazed June 21 July

37 Rotation grazing system Cattle is concentrated in a paddock for a short time, after which the paddock is rested. Field 3: Grazed July 21 August 28

38 Rotation grazing system. Field 4: Grazed August 28 Sept Rotation systems simulate natural grazing that occurred on the ancient grasslands for millions of years. These grasslands are adapted to being heavily grazed and then the herd moving on, so the grassland is rested from grazing, enabling shoot and root growth and seed production.

39 Rotation grazing system. Second year Start in Field 2: Grazed June 1-21 It allows resting all grass phenophases (regrowth, flowering, fructification, seed dissemination) 2 Poor condition E.g. If paddock # 1 is always grazed on June 1-21, seed production (and plant density later) of Poa compressa will be reduced.

40 Range Management: grassland productivity, soil organic carbon, C sequestration. 2 Poor condition 3 Good condition NPP, SOC, C It is possible to mitigate climate change by managing grazing

41 Governments spend $$$ to reduce emissions and increase capture of GHG For example: Carbon Capture and Storage (CCS)

42 Carbon capture and storage (CCS) The CO2 is compressed and transported by pipeline to be injected 1-2 km deep into a porous rock formation (into depleting oil reserves). Enhance oil recovery: The CO2 provides the pressure needed to increase the flow of the oil, which makes it easier to pump to the surface

43 Carbon capture and storage (CCS) Weyburn-Midale CO 2 Project One of the largest CO 2 storage project: Eight-year $80-million international project. This CCS project pipes CO2 from Beulah, North Dakota to Weyburn, Saskatchewan where it is injected 1.5 km deep into a depleted oil field.

44 Carbon capture and storage (CCS) Alberta Government invests $1.4 billion in carbon capture and storage (CCS) projects, and expects to store up to 5 million tonnes of CO2 per year by Something cheaper? (more efficient?) Alberta CCS Projects: 1) Shell Quest Provincial funding: $745 M over 15 years Companies involved: Shell Canada Limited, Chevron Canada Limited and Marathon Oil Canada Corporation. 2) Swan Hills Synfuels Provincial Funding: $285 M over 15 years Companies Involved: Swan Hills Synfuels. 3) Alberta Carbon Trunk Line Provincial funding: $495 M over 15 years Companies involved: Enhance Energy, Northwest Upgrading and Agrium.

45 CCS Rangelands: Carbon capture and storage (CCS) NPP (g / m2 / yr) Grassland 12,000 kg roots/ha/yr 6,000 kg of C /ha/yr (6 t C/ha/yr) (Steady-state system: t C ha-1 in Soil Organic matter (10-20% fine roots) Conant and Paustian, 2002 C

46 NPP (g / m2 / yr) Rangelands as carbon capture and storage systems Root density (cm/image) Grassland 20 % Warming No Grazing Light Grazing Heavy Grazing C grassland (root) production: 6 t C/ha/yr Grassland C sequestration may be reduced by 20 % with heavy grazing: 20 % of 6 = 1,2 t C/ha/yr Saskatchewan PFRA pastures: 728,000 ha We should expect annual increments in atmospheric carbon by 783,600 tonnes (comparable to placing almost 200,000 extra vehicles on the road) if grazing is increased from the current light intensity to a heavier livestock pressure.

47 NPP (g / m2 / yr) Root density (cm/image) More than half of the 22 M ha of Canadian rangelands are in less than good Rangelands: condition due to overgrazing. 11 M ha of rangelands may be improved by range management Grassland Carbon capture and storage (CCS) Warming No Grazing Light Grazing Heavy Grazing C grassland (root) production: 6 t C/ha/yr 20 % = 1,2 t C/ha/yr by grazing management 1,2 t of C/ha/yr x 11 M ha = 13,2 M t of C /yr Extra 13 millon tonnes of Carbon may be stored by improving range management. 20 % We can increase 20 % C capture through grazing management.

48 Carbon capture and storage (CCS) Investments, funds? CCS Projects Improved rangelands 5 million tonnes of CO2 13 million tonnes of CO2

49 Carbon capture and storage (CCS) Investments, funds? CCS Projects Improved rangelands Better invest in Range management research and extension

50 Thank you for your interest