Effects of insect mass outbreaks on the C and N balance in forest ecosystems

Grüning, Maren Marine

dc.contributor.advisor	Dippold, Michaela Prof. Dr.
dc.contributor.author	Grüning, Maren Marine
dc.date.accessioned	2019-06-27T08:16:20Z
dc.date.available	2019-06-27T08:16:20Z
dc.date.issued	2019-06-27
dc.identifier.uri	http://hdl.handle.net/21.11130/00-1735-0000-0003-C143-7
dc.identifier.uri	http://dx.doi.org/10.53846/goediss-7529
dc.language.iso	eng	de
dc.rights.uri	http://creativecommons.org/licenses/by-nc-nd/4.0/
dc.subject.ddc	634	de
dc.title	Effects of insect mass outbreaks on the C and N balance in forest ecosystems	de
dc.type	doctoralThesis	de
dc.contributor.referee	Dippold, Michaela Prof. Dr.
dc.date.examination	2019-05-31
dc.description.abstracteng	Intensive defoliation by phytophagous insects in forests is accompanied by high amounts of organic litter deposition which affects biogeochemical processes in soil, thereby changing nutrient recycling and release as well as the soil microbial community. Besides its effects on soil, defoliation has negative impacts on tree health, thus changing the trees’ metabolic processes and altering tree-soil interactions. In this thesis mass outbreaks of the nun moth (Lymantria monacha L.) and the pine-tree lappet (Dendrolimus pini L.) in two Scots pine forests (Pinus sylvestris L.) and two non-infested control forests in the federal state of Brandenburg, Germany, were investigated. The C and N inputs (solid and liquid) and the outputs (soil solution and gaseous soil emissions) during the outbreak years were quantified. Effects of soil C and N pools on microbial populations were quantitatively and qualitatively characterized by DNA-based methods (qPCR and DGGE followed by DNA sequencing) in the organic layers, the mineral soil, and other forest compartments. An additional microcosm incubation experiment with different organic matter treatments examined the effects of insect feces compared to needle litter on soil CO2 and N2O fluxes. Consequences of insect induced defoliation for tree nutrition and tree health were detected by a 15N uptake experiment of fine roots and the quantification of different N metabolites in needles and fine roots of infested and non-infested Scots pines. Further, effects on the trees phyllosphere and the understorey vegetation were detected by the above-mentioned DNA-based methods. The findings demonstrate that C and N pools, fluxes and turnover processes in the tree-soil-atmosphere continuum are heavily affected by insect mass outbreaks. Increased organic input triggered a change in microbial abundance and resulted in increased losses of C and N. At the same time, tree nutrition, phyllospheric colonization by microorganisms and mycorrhizal symbiosis is altered by the insect outbreaks. These results illustrate the complexity of process and flux modifications by insects and reveal the importance to evaluate changes differentiated temporally and spatially in multiple forest compartments to assess feedback links at ecosystem scale.	de
dc.contributor.coReferee	Jungkunst, Hermann Prof. Dr.
dc.subject.eng	Carbon	de
dc.subject.eng	Nitrogen	de
dc.subject.eng	Pinus sylvestris	de
dc.subject.eng	Lymantria monacha	de
dc.subject.eng	Brandenburg	de
dc.subject.eng	Disturbances	de
dc.subject.eng	Soil microbiology	de
dc.subject.eng	Forest	de
dc.subject.eng	Insects	de
dc.subject.eng	Phyllosphere	de
dc.subject.eng	N uptake	de
dc.subject.eng	Dendrolimus pini	de
dc.subject.eng	CO2	de
dc.subject.eng	N2O	de
dc.subject.eng	qPCR	de
dc.subject.eng	DGGE	de
dc.subject.eng	Scots pine	de
dc.subject.eng	Pests	de
dc.subject.eng	Global warming	de
dc.identifier.urn	urn:nbn:de:gbv:7-21.11130/00-1735-0000-0003-C143-7-4
dc.affiliation.institute	Fakultät für Forstwissenschaften und Waldökologie	de
dc.subject.gokfull	Forstwirtschaft (PPN621305413)	de
dc.identifier.ppn	1668074486

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