Headwater Riparian Forest-Floor Invertebrate Communities Associated With Alternative Forest Management Practices

Abstract

Headwater streams and their riparian zones are a common, yet poorly understood, component of Pacific Northwest, USA, landscapes. We describe the ecological importance of headwater stream riparian zones as habitat for forest-floor invertebrate communities and assess how alternative management strategies for riparian zones may impact these communities. We compared community composition of forest-floor invertebrates at increasing distances along trans-riparian (stream edge to upslope) transects in mature forests, clearcuts, and riparian buffers of approximately 30-m width with upslope clearcuts. Invertebrates were collected using pitfall traps in five replicate blocks of three treatments each in the Willamette National Forest, Oregon, USA. We measured microclimate and microhabitat variables at pitfall locations. Despite strong elevation and block effects on community composition, community analyses revealed a distinct "riparian" invertebrate community within 1 m of the stream edge in mature forest treatments, which was strongly related to cool, humid microclimate conditions. Invertebrate community composition in buffer treatments was far more similar to that of mature forests than to clearcuts; a pattern mirrored by microclimate. These results suggest that, within our study sites, forest-floor invertebrate distributions are strongly associated with microclimate and that riparian buffers of approximately 30-m width do provide habitat for many riparian and forest species. Riparian reserves may serve as effective forest refugia and/or dispersal corridors for invertebrates and other taxa, and their incorporation into watershed management plans likely will contribute to meeting persistence and connectivity objectives.

Forest-floor temperatures and soil moisture across riparian zones on first- to third-order headwater streams in southern New England, USA

“…In addition to the increased biological diversity inherent in the juxtaposition of aquatic and terrestrial habitats (Crow et al, 2000;Sabo et al, 2005), riparian zones have been shown to be unique from adjacent upland forest. Differences in vegetative composition (Goebel et al, 2003;Hagan et al, 2006) and in use by invertebrates (Rykken et al, 2007b), amphibians (Pauley et al, 2000;Perkins and Hunter, 2006;Crawford and Semlitsch, 2007), birds (DeGraaf and Yamasaki, 2000;Bub et al, 2004) and mammals (DeGraaf and Yamasaki, 2000;Ford et al, 2006) have been reported. The unique habitat qualities of riparian zones have been ascribed, in part, to their microclimatic conditions (Brosofske et al, 1997;Moore et al, 2005;Olson et al, 2007;Rykken et al, 2007a).…”

“…However the bulk of evidence in support of this comes from studies in more arid western forests (e.g., forest-floor invertebrates [Rykken et al, 2007b], amphibians [Olson et al, 2007]), where cool, moist microclimatic conditions in riparian zones are strongly different from those in adjacent upland forest (Rykken et al, 2007a).…”

Assessment of ecosystem services as an opportunity for the conservation and management of native forests in Chile

“…Higher water quality in streams associated to watersheds in the Andean Range, covered extensively with native forests, have been mentioned as an explanation for higher trout abundance compared to that reported for the Coastal Range and the Central Depression (Soto et al, 2006). Studies in the Northern Hemisphere show that forests with riparian buffers, resulted in a different forest invertebrate and aquatic invertebrate communities (Kiffney et al, 2003;Rykken et al, 2007) than in areas without forested buffers. Trout prey on both terrestrial and aquatic invertebrate communities (Elliott, 1973;Klemetsen et al, 2003) and they are most likely dependent on the communities associated to second-growth forests.…”

The influence of partial timber harvesting in riparian buffers on macroinvertebrate and fish communities in small streams in Minnesota, USA

“…Multiple studies have investigated the effects of riparian buffer width and morphologies to protect various aspects of the riparian community (see Lee et al, 2004;Olson et al, 2007), which depend on the function that the buffer is meant to serve (Rykken et al, 2007), as well as site-specific conditions. This study investigated the role of three riparian buffers on preserving the biodiversity and community structure of aquatic macroinvertebrate and fish assemblages in Minnesota streams.…”