 |
| Titel |
Effect of parameter choice in root water uptake models – the arrangement of root hydraulic properties within the root architecture affects dynamics and efficiency of root water uptake |
| VerfasserIn |
M. Bechmann, C. Schneider, A. Carminati, D. Vetterlein, S. Attinger, A. Hildebrandt |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1027-5606
|
| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 18, no. 10 ; Nr. 18, no. 10 (2014-10-27), S.4189-4206 |
| Datensatznummer |
250120504
|
| Publikation (Nr.) |
 copernicus.org/hess-18-4189-2014.pdf |
|
|
|
|
|
| Zusammenfassung |
| Detailed three-dimensional models of root water uptake have become
increasingly popular for investigating the process of root water uptake.
However, they suffer from a lack of information on important parameters,
particularly on the spatial distribution of root axial and radial
conductivities, which vary greatly along a root system. In this paper we
explore how the arrangement of those root hydraulic properties and branching
within the root system affects modelled uptake dynamics, xylem water
potential and the efficiency of root water uptake. We first apply a simple
model to illustrate the mechanisms at the scale of single roots. By using two
efficiency indices based on (i) the collar xylem potential ("effort") and
(ii) the integral amount of unstressed root water uptake ("water yield"),
we show that an optimal root length emerges, depending on the ratio between
roots axial and radial conductivity. Young roots with high capacity for
radial uptake are only efficient when they are short. Branching, in
combination with mature transport roots, enables soil exploration and
substantially increases active young root length at low collar potentials.
Second, we investigate how this shapes uptake dynamics at the plant scale
using a comprehensive three-dimensional root water uptake model. Plant-scale
dynamics, such as the average uptake depth of entire root systems, were only
minimally influenced by the hydraulic parameterization. However, other
factors such as hydraulic redistribution, collar potential, internal
redistribution patterns and instantaneous uptake depth depended strongly on
the arrangement on the arrangement of root hydraulic properties. Root systems
were most efficient when assembled of different root types, allowing for
separation of root function in uptake (numerous short apical young roots) and
transport (longer mature roots). Modelling results became similar when this
heterogeneity was accounted for to some degree (i.e. if the root systems
contained between 40 and 80% of young uptake roots). The average collar
potential was cut to half and unstressed transpiration increased by up to
25% in composed root systems, compared to homogenous ones. Also, the least
efficient root system (homogenous young root system) was characterized by
excessive bleeding (hydraulic lift), which seemed to be an artifact of the
parameterization. We conclude that heterogeneity of root hydraulic properties
is a critical component for efficient root systems that needs to be accounted
for in complex three-dimensional root water uptake models. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|