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Vegetation impacts soil water content patterns by shaping canopy water fluxes and soil properties
Author(s) -
Metzger Johanna Clara,
Wutzler Thomas,
Dalla Valle Nicolas,
Filipzik Janett,
Grauer Christoph,
Lehmann Robert,
Roggenbuck Martin,
Schelhorn Danny,
Weckmüller Josef,
Küsel Kirsten,
Totsche Kai Uwe,
Trumbore Susan,
Hildebrandt Anke
Publication year - 2017
Publication title -
hydrological processes
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.222
H-Index - 161
eISSN - 1099-1085
pISSN - 0885-6087
DOI - 10.1002/hyp.11274
Subject(s) - environmental science , stemflow , water content , soil water , throughfall , pedotransfer function , soil science , topsoil , field capacity , subsoil , macropore , precipitation , hydrology (agriculture) , beech , hydraulic conductivity , ecology , geology , chemistry , mesoporous material , biochemistry , physics , geotechnical engineering , biology , meteorology , catalysis
Soil water content is a key variable for biogeochemical and atmospheric coupled processes. Its small‐scale heterogeneity impacts the partitioning of precipitation (e.g., deep percolation or transpiration) by triggering threshold processes and connecting flow paths. Forest hydrologists frequently hypothesized that throughfall and stemflow patterns induce soil water content heterogeneity, yet experimental validation is limited. Here, we pursued a pattern‐oriented approach to explore the relationship between net precipitation and soil water content. Both were measured in independent high‐resolution stratified random designs on a 1‐ha temperate mixed beech forest plot in Germany. We recorded throughfall (350 locations) and stemflow (65 trees) for 16 precipitation events in 2015. Soil water content was measured continuously in topsoil and subsoil (210 profiles). Soil wetting was only weakly related to net precipitation patterns. The precipitation‐induced pattern quickly dissipates and returns to a basic pattern, which is temporally stable. Instead, soil hydraulic properties (by the proxy of field capacity) were significantly correlated with this stable soil water content pattern, indicating that soil structure more than net precipitation drives soil water content heterogeneity. Also, both field capacity and soil water content were lower in the immediate vicinity of tree stems compared to further away at all times, including winter, despite stemflow occurrence. Thus, soil structure varies systematically according to vegetation in our site. We conclude that enhanced macroporosity increases gravity‐driven flow in stem proximal areas. Therefore, although soil water content patterns are little affected by net precipitation, the resulting soil water fluxes may strongly be affected. Specifically, this may further enhance the channelling of stemflow to greater depth and beyond the rooting zone.