TREE- BASED INTERCROPPING SYSTEMS: A POTENTIAL LAND- USE SOLUTION FOR CLIMATE CHANGE MITIGATION IN CANADIAN AGRICULTURAL LANDSCAPES

Transcription

1 TREE- BASED INTERCROPPING SYSTEMS: A POTENTIAL LAND- USE SOLUTION FOR CLIMATE CHANGE MITIGATION IN CANADIAN AGRICULTURAL LANDSCAPES 3rd European Agroforestry Conference Agroforestry and Climate Change May 25, 2016 By Thevathasan NV*, Gordon AM, Wotherspoon A, Kiara Borden, Candice Unix, Marney Isaac, Graungaard K, Dunfield K, Jeffries D, Heck R, Coleman R and Voroney P * Correspondence author: nthevath@uoguelph.ca 1

2 TBI in Southwestern Ontario 2

3 UoG Agroforestry Research StaWon Established in 1987 Soil: sandy loam; calcareous parent material Density: 111 trees ha- 1, RCBD Tree row spacing: m Within row spacing: 1.0, 2.5 and 6 m 3 3

4 Gaps in Current Research Lack of empirical data for TBI systems and for specific tree species on C seq. Lack of data on belowground pools in TBI Carbon seq. over Wme in TBI systems - 25 years? Carbon sequestrawon potenwal of TBI systems, when compared to convenwonal agriculture systems? InformaWon on soil structural dynamics as influenced by TBI microbial induced GHG emissions in TBI? 4

5 Can belowground roots be quanwfied in TBI systems using a non- destrucwve method - GPR? Water uptake dynamics in a mature TBI system 5

6 Research Objectives 1. QuanWfy above and belowground carbon pools in tree biomass and soil 2. Determine quanwty and quality of C fluxes 3. Compare these carbon pools and fluxes in TBI to convenwonal agricultural systems. Adapted from Peichl et al.,

7 Tree Species 25 years old Poplar hybrid (Populus sp.) Black walnut (Juglans negro) Red oak (Quercus rubra) 111 trees ha trees ha -1 Norway spruce (Picea abies) 333 trees ha -1 White cedar (Thuja occidentalis) 7 7

8 Agricultural Crops Maize (Zea mays) Winter Wheat (Triticum aestivum) Soybean (Glycine max) Barley (Hordeum vulgare) 8

9 Carbon Pools Aboveground tree biomass Belowground tree biomass Soil organic carbon 9

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11 How does system level C content vary with density? C content per tree (kg C) 111 trees ha - 1 (t ha - 1 ) Hybrid poplar (+ 61.7) Red Oak (+ 22.4) Black walnut (+ 49.7) Norway spruce (+ 44.4) White cedar 48.6 (+ 24.8) trees ha - 1 (t ha - 1 ) trees ha - 1 (t ha - 1 )

12 C Pools: SigniQicance Summary of carbon pools (t C ha - 1 ) for five tree species in a 25- year- old TBI system as compared to a convenwonal agricultural system in southwestern Ontario. Hybrid Poplar Red Oak Black Walnut Norway Spruce White Cedar Soybean Monocrop Chapter 1: C Pools (Significance) Tree C Content SOC Total Ra@o of species: soybean 1.6:1 1.4:1 1.4:1 1.5:1 1.4:1 12

13 C Pools: SigniQicance Summary of soil carbon pool (t C ha - 1 ) difference between 13 years and 25 years ajer the establishment of the TBI system as compared to a convenwonal agricultural system in southwestern Ontario. SOC Hybrid Poplar Norway Spruce Soybean Monocrop 13 years ajer establishment (12.5) 25 years ajer establishment (15.8) Difference Soybean monocrop agriculture system has 15.8 t C ha -1 less than poplar Soybean monocrop agriculture system has 7.2 t C ha -1 less than spruce 13

14 Carbon Fluxes Likerfall Liker DecomposiWon Soil RespiraWon 14

15 C Fluxes: Findings - Litterfall Annual flux (g m - 2 ) for likerfall and other trap contents for five tree species in a 25- year- old TBI system (+ SE) Total Likerfall Other leaves Woody debris Other (fruits, seeds, buds. twigs, etc.) Walnut (+ 20) 21.1 (+ 30) 34 (+ 45) (+ 98) Poplar (+ 19) 70.4 (+ 61) 73.5 (+ 11) 37.8 (+ 18) Spruce 58.9 (+ 19) 75.3 (+ 50) 66.5 (+ 41) 37.8 (+ 16) Oak (+ 98) 35.2 (+ 24) (+ 49) 80.6 (+ 34) Cedar 32.7 (+ 8) (+ 46) 58.8 (+ 9) 12.8 (+ 8) 15

16 C Fluxes Likerfall and Liker DecomposiWon Liker collected from m 2 traps (2 mm mesh) between Sept Dec 2012 DecomposiWon measured from cm 2 2- mm mesh bags between Oct 2012 and

17 Comparing TBI to conventional agriculture 17

18 TBI vs. Conventional Agriculture Table 8. Annual carbon inputs (t C ha - 1 y - 1 ) from five tree species commonly grown in tree- based intercropping systems in comparison to convenwonal agricultural system planted with soybean) Aboveground tree C assimilawon Belowground tree C assimilawon Poplar Oak Walnut Spruce Cedar Soybean Likerfall C inputs Fine root turnover Above and belowground Crop C input 1 Total inputs Harvested soybean data obtained from Peng et al. (2012) 18

19 TBI vs. Conventional Agriculture Table 9. Annual carbon outputs (t C ha - 1 y - 1 ) from five tree species commonly grown in tree- based intercropping systems in comparison to convenwonal agricultural system planted with soybean) Poplar Oak Walnut Spruce Cedar Soybean Likerfall C outputs Root C output Crop C output C leachate Total outputs Harvested soybean data obtained from Peng et al. (2012) 2 Assuming C leaching rate of 200 mm y - 1 (Peichl et al., 2006) 19

20 TBI vs. Conventional Agriculture Table 10. Annual net carbon (t C ha - 1 y - 1 ) from five tree species commonly grown in tree- based intercropping systems in comparison to convenwonal agricultural system (planted with soybean) Poplar Oak Walnut Spruce Cedar Soybean Total inputs Total outputs Net Carbon

21 Summary and Final Thoughts TBI planted with hybrid poplar, red oak, black walnut, Norway spruce, and white cedar all have greater CSP when compared to convenwonal agriculture (soybean) The presence of perennial tree above and belowground C contribuwon ContribuWon of organic maker to the long term stable SOC pool 13 years Vs 25 years ajer establishment Crop rotawon is important to maintain SOC levels in agricultural systems negawve net loss of C in this study (soybean) 21

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23 Subsurface root geo- imaging with ground penetrawng radar Isaac and Anglaaere 2013 Ecology and EvoluWon Isaac et al Agriculture, Ecosystems and Environment

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25 Radargram processing for biomass eswmawon Borden et al Agroforestry Systems

26 Developing biomass predicwve relawonships 82.2g 5.1g 355.7cm m 2 P. abies Borden et al Agroforestry Systems

27 Coarse root carbon eswmawon Borden et al Agroforestry Systems kg C tree -1 Mg C ha -1 T. occidentalis 5.4 ± ± 0.0 P. abies 23.8 ± ± 0.4 Populus sp ± ± 0.3 Q. rubra 27.8 ± ± 0.6 J. nigra 27.7 ± ± 0.3 All trees 20.7 ± ± 0.3

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29 Soil water acquisiwon in TBI systems Levels of extracted δ 18 O in xylem water are matched to δ 18 O in water extracted from soil horizons, providing a natural marker of water acquisiwon zones. Direct inference MulW- source mass balance

30 Direct inference method: soil isotope profiles under poplar and walnut Uptake at ~20cm Uptake at ~10cm poplar walnut Link at el Agroforestry Systems

31 Findings i) water acquisiwon zones are tree species dependent, and ii) a shij in tree water acquisiwon to deeper in the soil profile over the growing season. Using isotopic techniques, we suggest that poplar and walnut root acwvity strawfy below the crop root zone later in the growing season, potenwally reducing compewwon for water resources.

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34 Chapter 2: Void Phase Analysis 34

35 3D Model ReconstrucWon

36 O1 2.0E (20.33%) O1-2.0W (9.46%) O1-2.0N (25.78%)

37 Conclusions Soil void characteriswcs (large and medium pores) were not significantly affected by tree species 37

38 conclusions Across both systems (TBI & Solecrop) there is a significant effect of Wme on void characteriswcs and penetrometer resistance. This indicates that the micro- scale soil structural effects on GHG emissions could be very dynamic. Therefore, the method is able to quanwfy an important mechanism affecwng GHG emissions. It would be valuable to evaluate this concept in more detail with the direct measurement of GHG emissions from the cores being collected for X- ray CT analysis.

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40 Results Species Effects l l l Overall greater abundance of nirs and nifh genes in oak planted soil Overall greater abundance of nosz in the poplar soil Abundance of 16s rrna significantly higher in oak when compared with walnut

41 Acknowledgement Funding received from the Agriculture and AgriFood Canada s Agricultural Greenhouse Gas Program (AGGP), Government of Canada, is greatefully acknowledged. 41

42 THANK YOU 42

43 C Pools: Findings Tree Carbon Figure 1. Mean carbon content (kg C) for each tree component plus mean carbon concentration (%) for five TBI tree species Chapter 1: C Pools (Findings) Mean Carbon Content (kg C per tree) a b b bc c Twigs Secondary Primary Trunk Roots Average [C] (%) 0 Hybrid Poplar Red Oak Black Walnut Norway Spruce White Cedar Tree Species 43

44 Future Work New The CSP of a long term TBI system CSP of five different tree species commonly found in TBI systems New Direc@on Fast growing species may need several short- term cuwng cycles Slow growing species will conwnue to sequester atmospheric C Can assess their CSP in various agroforestry systems (windbreaks, riparian buffers, etc.) Can assess the various economic returns based on each species contribuwon Net CSP can contribute towards carbon trading 44