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Trees Feed Microbes (and Microbes Feed the Trees)

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Soil nutrition is not a passive or one-way interaction. Instead, plants actively communicate their needs with soil microorganisms, and the soil community responds by making nutrients available to the rhizosphere.
  • 1. TTrreeeessFFeeeeddSSooiill MMiiccrroobbeessapresentation byConor Flynn

2. General Idea: Linking above- andbelow-ground processesPhloem and xylemRhizodeposition and LitterfallPriming EffectGirdlingGirdling severs phloem, eliminatesrhizodeposition, tests Priming EffectWeintraub MN, Scott-Denton LE, Schmidt SK, MonsonRK. The effects of tree rhizodeposition on soil exoenzymeactivity, dissolved organic carbon, and nutrientavailability in a subalpine forest ecosystem. Oecologia.2007;154(2):327338. 3. Site Description W of Denver, CO 3,000 meters above sea level Lodgepole Pine (Pinus contorta) Sandy Inceptisol w/ thin organiclayer Girdled in July 2004 Photosynthesis begins mid-April2005 4. Materials + MethodsNNuuttrriieenntt:: hhoommooggeenniizzeedd wwiitthh 00..55 MMppoottaassssiiuumm ssuullffaattee ((KK22SSOO44)),, tthheenn vvaaccuuuumm--ffiilltteerreedd aanndd cchheemmiiccaallllyy aannaallyyzzeedd ffoorrCCaarrbboonn aanndd NNiittrrooggeenn..BBiioommaassss:: cchhlloorrooffoorrmm ffuummiiggaattiioonn,, tthheenn aassaabboovvee.. SSuubbttrraacctt..EExxttrraacceelllluullaarr EEnnzzyymmee:: hhoommooggeenniizzeedd iinn ppHH55..00 bbuuffffeerr,, iinnccuubbaatteedd iinn fflluuoorriimmeettrriiccaassssaayyss wwiitthh tthheeiirr ssuubbssttrraattee;; aaccttiivviittiieess aarreennmmooll ooff rreeaaccttiioonn pprroodduucctt ppeerr hhoouurr ppeerr ggooff ddrryy ssooiill.. 5. Results: Extracellular Enzymes I Hydrolysis of chitin Mineralizes organic P 6. Results: Extracellular Enzymes II BG: Cellobiose AG: Starch BX: Xylans BC: Degrades cellulose to Cellobiose 7. Results: Extracellular Enzymes IIIPeroxidase: can degradelignin 8. Results: Microbial Carbon and Nitrogen 9. Results: Extracellular Enzymes IVLAP: hydrolysis of aminoacids from peptides 10. ConclusionsAfter ggiirrddlliinngg,, rroooottss bbeeggiinn ttoo ddiieeFFiirrsstt mmyyccoorrrrhhiizzaaee ddeeccaayy,, tthheenn llaabbiillee ssttaarrcchheess,, tthheenn cceelllluulloossee,, aanndd ffiinnaallllyylliiggnniinn ((~~66 mmoonntthhss))..In healthy forests.Microbes benefit from rhizodeposition in spring, (while soil still covered insnow) and increase in microbial biomass.Rhizodeposits are probably sugars, low in N.Microbes must immobilize N from proteins in soil.When this labile microbial N is mineralized it will result in increased Navailability for the trees. 11. Discussion: Trees Feed Soil MicrobesAnd Vice Versa!

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Trees Trees Feed Feed Soil Microbes Soil Microbes a presenta tion by Conor Flynn
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