The Deep Root System of Fagus sylvatica on Sandy Soil

Structure and Variation Across a Precipitation Gradient

verfasst von

Ina Christin Meier, Florian Knutzen, Lucia Muriel Eder, Hilmar Müller-Haubold, Marc Oliver Goebel, Jörg Bachmann, Dietrich Hertel, Christoph Leuschner

Abstract

When applied to climate change-related precipitation decline, the optimal partitioning theory (OPT) predicts that plants will allocate a larger portion of carbon to root growth to enhance the capacity to access and acquire water. However, tests of OPT applied to the root system of mature trees or stands exposed to long-term drying show mixed, partly contradicting, results, indicating an overly simplistic understanding of how moisture affects plant-internal carbon allocation. We investigated the response of the root system (0–240 cm depth) of European beech to long-term decrease in water supply in six mature forests located across a precipitation gradient (855–576 mm mean annual precipitation, MAP). With reference to OPT, we hypothesized that declining precipitation across this gradient would: (H1) cause the profile total of fine root biomass (FRB; roots OpenSPiltSPi2 mm) to increase relative to total leaf mass; (H2) trigger a shift to a shallower root system; and (H3) induce different responses in the depth distributions of different root diameter classes. In contradiction to H1, neither total FRB (0–240 cm) nor the FRB:leaf mass ratio changed significantly with the MAP decrease. The support for H2 was only weak: the 95% rooting depth of fine roots decreased with decreasing MAP, whereas the maximum extension of small coarse roots (2–5 mm) increased, indicating contrasting responses of different root diameter classes. We conclude that long-term decline in water supply leads to only minor adaptive modification with respect to the size and structure of the beech root system, with notable change in the depth extension of some root diameter classes but limited capacity to alter the fine root:leaf mass ratio. It appears that OPT cannot adequately predict C allocation shifts in mature trees when exposed to long-term drying. Graphical Abstract: [Figure not available: see fulltext.].

Organisationseinheit(en)

AG Bodenphysik
Institut für Bodenkunde

Externe Organisation(en)

Georg-August-Universität Göttingen
Philipps-Universität Marburg

Typ

Artikel

Journal

ECOSYSTEMS

Band

21

Seiten

280-296

Anzahl der Seiten

17

ISSN

1432-9840

Publikationsdatum

03.2018

Publikationsstatus

Veröffentlicht

Peer-reviewed

Ja

ASJC Scopus Sachgebiete

Ökologie, Evolution, Verhaltenswissenschaften und Systematik, Umweltchemie, Ökologie

Ziele für nachhaltige Entwicklung

SDG 13 – Klimaschutzmaßnahmen

Elektronische Version(en)

https://doi.org/10.1007/s10021-017-0148-6 (Zugang: Geschlossen)