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Belowground plasticity of European beech – Studies on the variability of beech fine root system size, structure, morphology, and anatomy, and on their impact on soil organic matter in the top- and subsoil of six beech forests with different bedrock types in Northern Germany

dc.contributor.advisorLeuschner, Christoph Prof. Dr.
dc.contributor.authorKirfel, Kristina
dc.date.accessioned2019-02-01T13:33:11Z
dc.date.available2019-02-01T13:33:11Z
dc.date.issued2019-02-01
dc.identifier.urihttp://hdl.handle.net/11858/00-1735-0000-002E-E57C-5
dc.identifier.urihttp://dx.doi.org/10.53846/goediss-7264
dc.language.isoengde
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/4.0/
dc.subject.ddc570de
dc.titleBelowground plasticity of European beech – Studies on the variability of beech fine root system size, structure, morphology, and anatomy, and on their impact on soil organic matter in the top- and subsoil of six beech forests with different bedrock types in Northern Germanyde
dc.typedoctoralThesisde
dc.contributor.refereeLeuschner, Christoph Prof. Dr.
dc.date.examination2018-08-29
dc.description.abstractengTrees’ rooting systems have a fundamental role in the acquisition of water and nutrients from the soil and they are thought to be inherently plastic with regards to their size, structure, morphology and anatomy in order to cope with the spatially and temporarily heterogeneous supply of nutrients and water in soil. Furthermore, fine roots have a prominent role in the C cycle of forest ecosystems. The largest terrestrial OC pool is located in soils, and forest soils are estimated to contain the largest share, with up to 70 % of SOC. A large portion of trees’ annually assimilated carbon is consumed by fine roots and dead fine roots and rhizodeposits are a major source of OC in soils, particularly in subsoils. Therefore, to accurately assess the distribution, abundance, morphology and anatomy of trees’ fine root system is of vital importance for understanding forest ecosystem functioning. Nonetheless, our knowledge on the belowground plasticity of trees and their role in the C cycle of forests is still incomplete, particularly with regards to the subsoil, although deep roots can be important for securing sufficient supply of nutrients and water and 30-60 % of the global SOC is stored in the horizons below the topsoil. The present thesis deals with the variability in the size, structure, morphology, and anatomy of the fine root system of Fagus sylvatica as well as with the impact of beech fine roots on OC stocks in the topsoil and subsoil of six mature European beech forests Northern Germany. For this comparative approach, study sites with comparable climatic conditions, age and stand structure but growing on different bedrock were selected in order to be able to examine variation in root system traits and C cycling in the soil in relation to soil chemical properties and soil fertility. Major study aims were to i) quantify total stand fine root biomass and necromass and to analyze variation in fine root distribution patterns in dependence on soil acidity and depth, ii) investigate beech fine root morphological adaptations to different regimes of nutrient availability in soils, iii) analyze the intraspecific variability in xylem anatomical and derived hydraulic traits of small- and medium-sized beech roots with particular focus to soil depth-dependent variation, and iv) assess the impact of beech roots on the amount, spatial distribution and chemical composition of SOM with regards to the effect of different parent materials. Quite unexpectedly, significant relationships between FRB profile totals and soil acidity did not appear. Instead, the depth of the profile was shown to be the most important determinant of overall fine root system size. Higher silt and oxalate-extractable Fe contents in the rooted samples of one site (GR) suggest an increased foraging precision through root deployment in nutrient-rich patches in soils with low background fertility. Other than FRB, the amounts of necromass appeared to be related to site fertility, assumedly for the main part caused by an increase in fine root mortality. Across the investigated sites and across soil layers within one site, root morphological traits (mean fine root diameter, SRL, SRA, RTF) showed considerable variation. The largest differences emerged between the different layers within on profile, while a consistent relation in root morphological traits to soil acidity or base saturation did not appear. At half of the sites maximum RTF values were reached in the lower subsoil, presumably due to increased nutrient availability in these horizons. A significant relation of the investigated xylem anatomical and functional traits (D, Kp, VD, relative vessel lumen area) to soil depth could not be established. Instead, all traits showed a strong dependence on root diameter and thus root age. The maximum vessel diameter appeared to be restricted in the investigated roots, which may display a trade-off between hydraulic efficiency and hydraulic safety as well as mechanical requirements. Another main result of this study is the high plasticity in xylem architectural and hydraulic traits of similar-sized beech roots independent of soil depth, which indicates the existence of different functional types of roots with respect to water uptake and conduction. Furthermore, this study shows that the main input of SOC in the subsoil originates from roots and that root-derived SOM also considerably contributes to SOC stocks in the topsoil. The results emphasize the importance of soil texture and mineralogy as well as fine root mass as major determinants of the SOC contents and stocks in the subsoil. Most likely, soil texture and mineralogy have a twofold effect on SOC sequestration in the subsoil: firstly, through organo-mineral association by which SOM is stabilized and protected from microbial degradation. Secondly, soil texture may as well indirectly assert influence on SOC sequestration via shaping the amount of root-borne OM inputs to the soil. Overall, this study supports the notion, that the rooting system of European beech is highly responsive to external (soil) factors, which is interpreted as an adaptive belowground strategy which enables the tree species to colonize a wide range of soil types. Furthermore, the results emphasize the prominent role of fine roots as a major determinant of SOC contents and stocks particularly in the subsoil and underline the importance of considering subsoil horizons in C inventories for accurately modeling terrestrial C cycling.de
dc.contributor.coRefereeHölscher, Dirk Prof. Dr.
dc.subject.engFagus sylvatica, root system plasticity, subsoil, deep roots, hydraulic conductivity, vascular differentiation, carbon storage, root biomassde
dc.identifier.urnurn:nbn:de:gbv:7-11858/00-1735-0000-002E-E57C-5-6
dc.affiliation.instituteBiologische Fakultät für Biologie und Psychologiede
dc.subject.gokfullBiologie (PPN619462639)de
dc.identifier.ppn104823164X


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