The trophic basis of reference and post-fire stream food webs 10 years after wildfire in Yellowstone National Park

Abstract

Wildfi re disturbance can alter stream ecosystems in numerous ways including loss of riparian litter inputs, altered fl ow regimes, shifts in resource allocations, and changes in biotic community structure. While some information exists on long-term recovery of streams following wildfi re, patterns in trophic dynamics are poorly understood. This study involved comparison of trophic pathways in reference and post-fi re streams in Yellowstone National Park (YNP) in 1998, ten years after wildfi re. 2 nd and 3 rd order post-fi re catchments in Cache Creek, YNP showed an increase in autochthonous grazing pathways compared to reference streams. The shift from detrital to grazing pathways, however, was less pronounced in 1998 (10-yrs post-fi re) than it was in 1990 (2-yrs post-fi re). Post-fi re stream energy pathways showed an initial shift to autochthonous resources followed by recovery toward pre-fi re allochthonous pathways over the fi rst post-fi re decade. Increasing energy derived from allochthonous resource pathways is expected to continue until it reaches pre-fi re conditions in Yellowstone streams.

Effects of wildfire of varying severity on benthic stream insect assemblages and emergence

“…Inputs of terrestrial organic matter did not differ among burn categories (B. Jackson, University of Idaho, unpublished data). Both Chironomidae and Baetis shift to autochthonous resources after fire (Mihuc and Minshall 2005). However, mean periphyton biomass for unburned, low-severity, and high-severity reaches was 5.3, 3.6, and 5.6 mg/m 2 , respectively, and did not significantly differ among burn categories .…”

Climate change, forests, fire, water, and fish: Building resilient landscapes, streams, and managers

“…In general, it is clear that fire and subsequent effects can disrupt invertebrate communities in segments of small streams, and that at longer time scales, effects depend on the severity and extent of the fire, subsequent hydrologic disturbance, and the characteristics and recovery of riparian vegetation. There is a substantial body of literature that initially defined the anticipated responses of stream communities and food webs to the extended effects of wildfire (e.g., Minshall and others 1989Minshall and others , 1997Minshall and others , 1998Minshall and others , 2001Minshall and others , 2004Robinson and Minshall 1996;Mihuc and Minshall 2005). The generalized prediction emerging from this work can be summarized as an ecological succession in a temporal frame (Minshall and others1989;Dunham and others 2003;Minshall and others 2004).…”

“…Subsequent efforts have integrated physical and ecological processes related to fire, and these concepts have been temporally categorized as short-term (i.e., <1 year), mid-term (1-10 yr), and long-term (10s to 100s of years) (e.g., Minshall and Brock 1991;others 1998, 2001;Mihuc and Minshall 2005). Concomitantly, spatial context is critical because heterogeneity in fire severity, stream or watershed characteristics, and ecological communities constrains subsequent events and ecological responses.…”

Decomposition of Fire Exposed Eucalyptus Leaves in a Portuguese Lowland Stream

“…However, changes in environmental conditions, community structure and/or stream energy pathways are likely to occur after fires (MINSHALL et al, 2001a;MIHUC and MINSHALL, 2005) modulating the present results -this study was conducted, in autumn, in an eucalyptus stream unaffected by fire events. Further investigation on postfire scenarios and comparative long-term studies using eucalyptus streams affected and unaffected by fire are needed for a correct evaluation of the structural and functional changes in stream ecosystems affected by fires.…”

“…Previous research indicate that post fire instream alterations are largely due to the loss of terrestrial vegetation which can lead to altered stream morphology and substratum characteristics (MINSHALL et al, 2003a), elevated runoff, increased ions concentration and increased suspended sediments and particulate organic matter (HAUER and SPENCER, 1998;MINSHALL et al, 2001a;FERREIRA et al, 2005), although changes in water quality may last for as short as 3 months (STEPHENS et al, 2005). Moreover, the disappearance of the riparian vegetation may result in a shift from a heterotrophic to an autotrophic system as the allochthonous litter input to the stream is reduced and the water surface exposed to solar irradiation is increased (MIN-SHALL, 2003b;MINSHALL et al, 2001bMINSHALL et al, , 2003aMIHUC and MINSHALL, 2005). However, very little is known about the fate of the large amount of leaves that remain in the riparian areas and saturate the stream channel after fires.…”