|SREL Reprint #1841|
Interspecific leaf interactions during decomposition in
aquatic and floodplain ecosystems
Abstract. An experiment was designed to test the importance of the potential
interaction (inhibition or enhancement) between slow and fast decaying leaf
species on processing rates in a stream and its floodplain. The decomposition of
water oak (Quercus nigra) and sweetgum (Liquidambar styraciflua) in
single-species packs was compared with water oak plus sweetgum in
mixed-species packs within three habitats (stream snags, floodplain pools, and
elevated floodplain surfaces) at three sites in coastal plain streams.
Fast-decaying sweetgum leaves did not enhance the rate of oak decomposition.
Sweetgum leaves in mixed packs decomposed more slowly than single species
packs in seven out of nine comparisons. Increases in bacterial density on leaves
were depressed in mixed species packs relative to single-species sweetgum
packs. Fungal hyphae could not be observed in mixed or single-species packs.
The effect of oak leaves on sweetgum leaves was affected by frequency and
period of inundation. Macroinvertebrate shredders were rare or absent from
most leaf packs collected from stream snags and floodplain pools. Over 40% of
leaf packs placed in the stream contained no shredders, while another 28%
contained <0.001 g shredders/g leaf dry weight. Therefore, shredders were too
rare to influence overall leaf processing rates. These studies suggest that
microbial processing accounts for most leaf decomposition and oak leaf leachate
is shown to be inhibitory to microbial processing of sweetgum leaves.
SREL Reprint #1841
McArthur, J.V., J.M. Aho, R.B. Rader, and G.L. Mills. 1994. Interspecific leaf interactions during decomposition in aquatic and floodplain ecosystems. Journal of the North American Benthological Society 13:57-67.