You are here

Ecological linkages between headwaters and downstream ecosystems: Transport or organic matter, invertebrates and wood down headwater channels

TitleEcological linkages between headwaters and downstream ecosystems: Transport or organic matter, invertebrates and wood down headwater channels
Publication TypeJournal Article
Year of Publication2007
AuthorsWipfli, MS, Richardson, JS, Naiman, RJ
JournalJournal of the American Water Resources Association
Volume43
Pagination72–85
Abstract

Headwater streams make up a large proportion of the total length and watershed area of fluvialnetworks, and are partially characterized by the large volume of organic matter (large wood, detritus, and dissolvedorganic matter) and invertebrate inputs from the riparian forest, relative to stream size. Much of thoseinputs are exported to downstream reaches through time where they potentially subsidize river communities.The relative rates, timing, and conversion processes that carry inputs from small streams to downstream reachesare reasonably well quantified. For example, larger particles are converted to smaller particles, which aremore easily exported. Also, dissolved organic matter and surface biofilms are converted to larger particles whichcan be more easily intercepted by consumers. However, the quality of these materials as it affects biologicalactivity downstream is not well known, nor is the extent to which timing permits biological use of those particles.These ecological unknowns need to be resolved. Further, land uses may disrupt and diminish materialtransport to downstream reaches by removing sources (e.g., forest harvest), by affecting transport and decompositionprocesses (e.g., flow regulation, irrigation, changes in biotic communities), and by altering mechanisms ofstorage within headwaters (e.g., channelization). We present conceptual models of energy and nutrient fluxesthat outline small stream processes and pathways important to downstream communities, and we identify informationalgaps that, if filled, could significantly advance the understanding of linkages between headwaterstreams and larger rivers. The models, based on empirical evidence and best professional judgment, suggest thatnavigable waters are significantly influenced by headwater streams through hydrological and ecological connectivities,and land use can dramatically influence these natural connectivities, impacting downstream riverineecosystems.

DOI10.1111 ⁄ j.1752- 1688.2007.00007.x
Username Tag: