Ectomycorrhizal Community Structure and Fi,Mction 2000
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Ectomycorrhizal community structure and fi,mction in relation to forest residue harvesting and wood ash applications Shahid Mahmood LUND UNIVERSITY Dissertation 2000 A doctoral thesis at a university in Sweden is produced either as a monograph or as a collection of papers. In the latter case, the introducto~ part constitutes the formal thesis, which summarises the accompanying papers. These have either already been published or are manuscripts at various stages (in press, submitted or in ins). ISBN9!-7105-138-8 sE-LuNBDs/NBME-oo/lo14+l10pp 02000 Shahid Mahmood Cover drawing: Peter Robemtz I DISCLAIMER Portions of this document may be illegible in electronic image products. Images are produced from the best available original document. Organhtion Documentname LUND UNIVERSITY I DOCTORALDISSERTATION Department of Ecology- Mtcrobial Ecology I “eda fday16,20@ Ecology Building, S-223 62 Lund, Sweden I coDfw SE-LUNBDSINBME-OOI1 OI4+I 10 pp Author(a) sponsoringOrgmiration Shahid Mahmood T&feandsubtitls Eotomycorhkal community structure and function in relation to forest residue hawesting and wood ash applications Ectomycorrhizal fungi form symbiotic associations with tree roots and assist in nutrient-uptake and -cycling in forest ecosystems, thereby constitutinga most significantpart of the microbial community. The aims of the studies described in this thesis were to evaluate the potential of DNA-baeed molecular methods in below-ground ectomycorrhizal community studies and to investigate changes in actomycortilzal communities on spruce roots in sites with different N deposition, and in sites subjected to harvesting of forest rasidues or application of wood ash. The ability of selected ectomycorrhizal fungi to mobilise nutriente from wood ash and to colonise root systems in the presence and absence of ash was also studied. In total 39 ectomycorrhizal species were detected in the experimental forests located in southern Sweden. At each site five to six species colonised around 60% of the root tips. The dominant species, common to the sites, were Tylospora fibrillosa, Theleptrora terreatris and Cenococcum geoptrilum. Differancas between two sites with differing levels of N deposition suggested that community structure may be influenced by N deposition, although site history, location and degree of isolation may also influence species composition. Repeated harvesting of forest residues reduced numbers of mycorrhizai roots in the humus layer to approximately 50% of that in control plots but no shift in the actomycorrhizal community could be detected. At another site, application of granulated wood ash induced a shift in ectomycorrhizal community structure and three ectomycorrhizal fungi (“ash fungi”)were found to colonise ash granules. Two “ash fung~ showed a superior ability to solubilise stabilised wood ash in laboratory experiments compared to other ectomycorrhizal isolates from the same site. In laborato~ microcosms containing intact myoorrhizal myceiia, colonisation of wood ash patches by ons “ash fungus” was good whereas colonisation by Pi/oderma croceum was poor. In a competition experiment with these two fungi, colonisation of spruce roots by the “ash fungus” increased significantly in the presence of wood ash, whereas colonisationby P. croceum decreased. ~* Ectomycorrhiza, Communiv stmcture, Sprucer pCR.RFLp, ITS region, rDNA, N deposition, Forest residue, Wood ash, Tricalcium phosphate, Solubilisation, Calcium oxalate, P uptake, “C allocation, Wocd ash coloniestkm, Spruce colonisation,Competition ctasifiition system*or index tsrms(iiolly) .%ppkmentay biblfogqbicalinformation I ~ Eng~~ IssNaadkeytias ‘BN 91-7105-136-8 Recipient’snotes Nomberofpasu 110 Price Securitycfasdfiidmr Shahid Mahmood, Department of Ecology - Microbial Ecology, Lund University, S-22362 Lund, Sweden 1,thsnadsm&d, beii &s copydgbtownerof the abstractof the abowe-mentioneddisertatio~ bueby grantto affreference ~~@lJ-~~ - e the abstmctof tbs abovHocntiOosddksertation. April 16,2000. Sii Date Ectornycorrhizal community structure and function in relation to forest residue harvesting and wood ash applications Shahid Makmood LUND UNIVERSITY Akademisk avhandling, som for avlaggande av filosofie doktorsexamen vid matematisk-naturvetenskapliga fakulteten vid Lunds Universitet, kommer att offentligen forsvaras 3 Blt?JHal/en, Ekologihuset, Solvegatan 37, Lund. Tisdagen 16 Maj 2000, kl 10W. The thesis will be defended in English. The cover illustration The picture illustrates the proposed model that. forest residues can be used for bioenergy production and resultant ashes can be applied back to the forest soils to compensate the lost nutrients. The bioenergy from forest residues is ‘C02-neutral’ and has been regarded as ‘environmentally friendly’. DNA-based molecular studies suggested that wood ash application might induce a shift in the ectomycorrhkzd community on the roots. The wood ash granules collected from the field were normally colonised by ectomycorrhizal mycelia. The functional aspects of these ectomycorrhizal fungi in nutrient mobilisation and acquisition fkom wood ash are also described in thk thesis. Contents 1. List of papers 2. Important results 3. Background Biofuels as an energy source Soil acidification Wood ash as a liming agent 4. Mycorrhiza Methods for studying ectomycomh~al communities 5. Effects of pollution and forest management on ectomycorrhizal corn] Effects of N deposition Effects of forest harvesting practices Effects of ash fertilisation and liming 6. Experimental approaches Field sites Community studies Laboratory studies 7. Results and Discussion Community studies Functional aspects of selected ectomycorrhizal fimgi 8. Conclusions 9. Acknowledgements 10. References 11. Papers I-V 12. Appendix List of papers This thesis is based on the following papers, which will be r numerals. I Erland, S., Jonsson, T., Mahmood, S., Finlay, R ectomycomhizal community structure in two Picea abies Scandinavian Journal of Forest Research 14 (3): 209-217 II Mahrnood, S., Finlay, R.D., Erland, S. 1999. Effects of n residues on the ectomycorrhizal community in a SW Phytologist 142 (3): 577-585. III Mahmood, S., Finlay, R.D., Wallander, H., Erland, colonisation of roots and ash granules in a spruce forest tr ash. (submitted to Forest Ecology and Management). Iv Mahmood, S., Finlay, R.D., Erland, S., Walkmder, H colonisation of wood ash by ectomycorrhizal fungi i fertilised spruce forest. (manuscript). v Mahmood, S. 2000. Colonisation of spruce roots by two fimgi in wood ash amended substrates. (manuscript). Thepubiishedpapers are reproduced by kindpermissionfiom th Important results The aims of the studies described in this thesis were to evall (ITS-typing) methods in below-ground ectomycorrhizal (E investigate changes in ectomycorrhlzal communities on spru deposition, and in sites subjected to harvesting of forest resi{ Four spruce forests in southern Sweden (Sk&ne & Halland) methods to identifi mycorrhizal fungi colonizing single r{ ectomycorrhizal fungi to mobilise nutrients from wood ash the presence and absence of ash was also studied. In total 39 ectomycorrhizal species were detected (Papers At each site five to six species colonised around 60% of t] Dominant species, common to the sites, were Tylospora, and Cenococcuin geophilum (Papers I, II, III). Differences between two sites with differing levels c community structure may be influenced by N deposition and degree of isolation may also influence species compo Repeated harvesting of forest residues reduced numbf humus layer to approximately 50% of that in control community could be detected (Paper II). At another site, application of granulated wood ash indt structure and three ECM iimgi (“ash fi.mgi”) were found III). Two “ash fimgi” showed a superior ability to solubilise s experiments compared to other ECM isolates from the saI In laboratory microcosms containing intact mycorrhizal ash patches by one “ash fimgus” was good whereas cola was poor (Paper IV). In a competition experiment with these two fimgi, COIC “ash fimgus” increased significantly in the presence of W( Pilodei-ma croceum decreased (Paper V). * Background Biofuels as an energy source In Sweden there is a growing interest in the utilisation of forest derived biomass as biofuel. The main reasons for using bioenergy are the possible hazards of conventional energy sources to the environment such as production of greenhouse gases and disposal of nuclear wastes,, Bioenergy is regarded as one possible substitute for fossil fiels, which contribute substantially to the rise of carbon dioxide in the atmosphere and thus cause long-term changes in the global carbon cycle (Schkunadinger et al., 1995; Schlamadinger and Marland, 1996). There are a number of studies which indicate that forest derived biofuels have a great potential for mitigating atmospheric C02 increase in an environmentally acceptable manner (Burschel et al., 1993; Dixon et al., 1993a,b; Kursten and Burschel, 1993; Hall and House, 1994; Schlamadinger and Marland, 1999). In a reeent report (Energilaget, 1999) on energy in Sweden it has been reported that during the year 1998, biofiels provided almost 16%(=63 Twh) of the total energy requirements (= 395 Twh). The current use of biofuels originating from forests corresponds to = 67 Twh, of which =48 Twh is derived from forest residues or by-products from the forest industry. The technical potential for energy production from forest residues has been estimated at between 22-24 Twh and it has been estimated that this figure may be