Session 6.5 shade trees species composition  affect water dynamics, western ghats, india
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Session 6.5 shade trees species composition affect water dynamics, western ghats, india

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Session 6.5 shade trees species composition  affect water dynamics, western ghats, india Session 6.5 shade trees species composition affect water dynamics, western ghats, india Presentation Transcript

  • SHADE TREE SPECIES COMPOSITION AFFECT WATER DYNAMICS IN COFFEE AGRO-FORESTRY SYSTEMS OF THE WESTERN GHATS. INDIA. Vaast P1.3. Charbonnier F1. Guillemot J1. Maruti G2 & Devakumar AS2 1.CIRAD. Montpellier. France. 2UAS Bangalore. College of Forestry. Ponnampet. Karnataka. India. 3ICRAF Nairobi. Kenya. This study is part of the CAFNET Project: Connecting. enhancing and sustaining environmental services and market values of coffee agroforestry in Central America. East Africa and India Financed by European Commission Program on Environment in Developing Countries
  • Context • • India 5th largest world coffee producer (70% Robusta) Production concentrated in the Western Ghats – One of the world hotspots of biodiversity • Climate characterized by South West Monsoon & Long dry period (5 months) • Traditionally, coffee grown under multistrata native shade trees (>50 spp /Ha) • Rapid expansion of coffee over last 30 years • Since the 80s, changes in coffee management => tree tenure, volatility of coffee price (diversification: pepper/timber)=> exotic trees (i.e. Grevillea robusta) replacing native species. • Water is one key ecosystems service identified by stakeholders 1977 1997 2007
  • Study sites • 6 sites (3 presented here) • Western Site: Bettageri 3 500 mm yr-1 • Central Site: Pachat 2 000 mm yr-1 • Eastern site: Nanjarayapatna 1000 mm • For each site. two 1 000 m² plots: – shaded trees predominantly exotic (Grevillea robusta >80%) – shaded trees predominantly native species (>80%) Nanjarayapatna • Chettimany Bettageri Chettaly Hoddur Pachat • Plots of a same site nearest possible from each other; The bio-physical characteristics of plots the most similar possible to only compare the impact of shade composition on hydrological fluxes. View slide
  • Material & Methods • Characteristics of coffee and trees (LAI, BA..) • Hourly meteorological data (ETP) • Daily sap flow monitoring – Granier probe => Trees – Dynamax probe => Coffee • Daily rain interception (trees & coffee canopy) • Stemflow (coffee & trees) • Soil water content down to 1.6 m (Diviner 2000) • Runoff View slide
  • Water fluxes GR = I + (Se) + T + R + ΔS + Drainage Transpiration Gross Rainfall Shade tree Interception Interception Soil evaporation Coffee Runoff Soil water stock Drainage
  • Coffee Shade trees N Western Site Exotic Native LAImax* LAImin* N LAImax* 1120 1420 2.3 (0.5) 2.6 (0.7) 1.5 (0.4) 1.3 (0.4) 1210 650 1.4 (0.3) 1.0 (0.4) 2210 1360 2 .0 (0.9) 2.4 (0.9) 1.5 (0.7) 1.7 (0.6) 500 480 1.7 (0.3) 0.9 (0.3) 1120 1560 3 (0.7) 2.6 (0.6) 2.1 (0.5) 1.8 (0.4) 430 150 0.9 (0.1) 1.0 (0.5) CentralSite Exotic Native Eastern Site Exotic Native Coffee Density per ha (N). Basal area in m²/ha (BA). Leaf area index at the end of the monsoon (LAImax). Leaf area index at the end of the dry season (LAImin) Standard deviation betwween parenthesis Images taken from canopy analyzer CI 110. CID Heterogenous canopy. typical plurispecific. native plot Homogenous canopy. typical of monospecific. exotic. Grevillea robusta plot Robusta coffee canopy
  • Transpiration Tree Interception Soil evaporation Coffee Gross Rainfall Runoff Soil water stock Drainage Gross throughfall Coffee Tree SF SF Rainfall mm Western Site Exotic Center Site Exotic Eastern Site Exotic Run-Off Tree (%) System (%) % Native 930 % % 71 0.3 5.0 3 25 4.0 0.3 2.9 4 20 5.0 78 0.4 2.9 5 18 5.2 85 2 040 % 78 3 368 Native Native Interception 0.5 2.0 6 15 5.7 78 0.7 0.6 1 22 3.8 81 1.3 1.0 4 19 3.4 Gross Rainfall (Gross RF) measured from June to October. Throughfall as direct rain reaching the soil. Coffee stem flow (Coffee SF). Tree stem flow (Tree SF). and Interception expressed in percentage of the Gross rainfall
  • Estimated drainage from Total rainfall. net rain infiltration into the soil and total system transpiration (coffee + tree) in native and exotic plots of the three sites (Eastern. Central and Western) of the Kavery watershed. Total System Estimated Infiltration Transp. Transp. (mm) (mm) (mm) (mm) (mm) 3 529 1 610 287 484 771 838 1 925 581 777 1 357 567 1 499 267 541 718 781 1 630 492 658 1149 480 537 118 200 318 219 601 217 290 508 93 Transpiration Drainage Plot Exotic Tree (mm) Western Coffee Rainfall Site Net rain Native Central Exotic 2 012 Native Eastern Exotic Native 1 024
  • Conclusion • Coffee canopy intercepts largest part (9-21%) of rainfall (shade tree composition not important) • Coffee under native trees transpires more than under exotic ones • Native trees transpire more than exotics (dry season), but exotics dry out more topsoil • Runoff comparable in exotic and native plots (3-6%) • Rain infiltration higher in native than exotic • Drainage below root zone lower in native than exotic •  less water recharging aquifers/rivers in native than exotic plots