A hydrological framework for biogeochemical studies
Helmut
Elsenbeer, University of Potsdam, helsenb@rz.uni-potsdam.de
(Presenting)
Jorge
Marcos de
Moraes, CENA/Universidade de Sao Paulo, jmmoraes@cena.usp.br
The ecosystem fluxes of many nutrients are tightly coupled with the flow of water, and the quantification of these fluxes therefore requires quantitative knowledge of hydrological flowpaths. This presupposes that the hydrological functioning in terms of the partitioning of rainfall into various flowpaths is known, because without this knowledge, any field monitoring program for the quantitative assessment of nutrient fluxes is bound to be biased. And yet, many, if not most, nutrient cycling studies pay scant attention to the hydrological functioning of their systems. Instead, the monitoring design of many such studies seems to be predicated on the belief that vertical flowpaths prevail. In particular, this belief rules out lateral flowpaths near the soil surface.
This belief can be traced back to both an outdated view of hydrological processes and to successful biogeochemical studies of systems whose flowpaths happened to be predominantly vertical, hence justifying the monitoring design employed. In view of the now well-documented diversity of ecosystems with respect to their hydrological functioning this belief in the prevalence of vertical hydrological flowpaths has become untenable, and so has the unreflected application of monitoring designs motivated by this belief.
We explore how the interpretation of biogeochemical studies may go astray if a traditional monitoring design based on the verticality assumption is applied to an ecosystem with lateral hydrological flowpaths, and we present the blueprint of a minimal hydrological field assessment designed to select a field monitoring program for biogeochemical studies that is commensurate with a site's hydrological functioning.