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Importance of Organic Debris Dams in the Structure and Function of Stream Ecosystems
Author(s) -
Bilby Robert E.,
Likens Gene E.
Publication year - 1980
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.2307/1936830
Subject(s) - organic matter , streams , tributary , debris , environmental science , ecosystem , large woody debris , particulates , total organic carbon , river ecosystem , particulate organic matter , dissolved organic carbon , particulate organic carbon , hydrology (agriculture) , ecology , environmental chemistry , geology , chemistry , oceanography , biology , geography , habitat , phytoplankton , nutrient , riparian zone , computer network , cartography , geotechnical engineering , computer science
Removal of all organic debris dams from a 175—m stretch of second—order stream at the Hubbard Brook Experimental Forest in New Hampshire led to a dramatic increase in the export of organic carbon from this ecosystem. Output of dissolved organic carbon (<0.50 μm) increased 18%. Fine particulate organic carbon (0.50 μm—1 mm) export increased 632% and coarse particulate organic matter (>1 mm) export increased 138%. Measurement of the standing stock of coarse particulate organic matter on streambeds of the Hubbard Brook Valley revealed that organic debris dams were very important in accumulating this material. In first—order streams, debris dams contain nearly 75% of the standing stock of organic matter. The proportion of organic matter held by dams drops to 58% in second—order streams and to 20% in third—order streams. Organic debris dams, therefore, are extremely important components of the small stream ecosystem. They retain organic matter within the system, thereby allowing it to be processed into finer size fractions in headwater tributaries rather than transported downstream in a coarse particulate form.