Are forested buffers an effective conservation strategy for riparian fauna? An assessment using meta‐analysis

Abstract

Historically, forested riparian buffers have been created to provide protection for aquatic organisms and aquatic ecosystem functions. Increasingly, new and existing riparian buffers are being used also to meet terrestrial conservation requirements. To test the effectiveness of riparian buffers for conserving terrestrial fauna, we conducted a meta-analysis using published data from 397 comparisons of species abundance in riparian buffers and unharvested (reference) riparian sites. The response of terrestrial species to riparian buffers was not consistent between taxonomic groups; bird and arthropod abundances were significantly greater in buffers relative to unharvested areas, whereas amphibian abundance decreased. Edge-preferring species were more abundant in buffer sites than reference sites, whereas species associated with interior habitat were not significantly different in abundance. The degree of buffer effect on animal abundance was unrelated to buffer width; wider buffers did not result in greater similarity between reference and buffer sites. However, responses to buffer treatment were more variable in buffers <50 m wide, a commonly prescribed width in many management plans. Our results indicate that current buffer prescriptions do not maintain most terrestrial organisms in buffer strips at levels comparable to undisturbed sites.

Riparian Partial Harvesting and Upland Clear Cutting Alter Bird Communities in a Boreal Mixedwood Forest

“…Although wide buffers provide breeding habitat for many forest bird species (reviewed in [48]), the primary function of narrow buffers is as travel corridors and foraging areas [55]. Partial harvesting within riparian buffers in our study did not appear to diminish their value as movement corridors during the post-breeding/fall migration period, since capture rates and movement patterns within the buffers were unaffected.…”

“…We did not see a crowding effect in our study, possibly because (1) partial harvesting rendered our buffer strips less suitable for forest interior species; or (2) the area surrounding our cut blocks was not as extensively harvested as elsewhere and displaced birds were able to find suitable habitat elsewhere [16]. Alternatively, Marczak et al [48] suggest that increases in total breeding bird abundance in riparian strips post-harvest may be driven by increases in edge species taking advantage of the availability of high-quality feeding habitat. While populations of early successional/edge species did increase post-harvest in our riparian strips, these were more than offset by the negative effects of partial harvesting on mature forest species.…”

Environmental and Anthropogenic Factors Influencing Salamanders in Riparian Forests: A Review

“…These buffer zones provide shade and reduce sediment and nutrient (e.g., road salts, nitrates, phosphates) loading from erosion and runoff due to anthropogenic activities such as timber harvest, prescribed burns, road maintenance, and agricultural practices. Buffers help to maintain stream conditions, such as hydrologic stability, across seasonal and climatic gradients as well as provide adjacent riparian habitat suitable for salamanders [10,58]. For instance, Pacific giant salamanders (Dicamptodon tenebrosus), southern torrent salamanders (Rhyacotriton variegatus) and Columbia torrent salamanders (Rhyacotriton kezeri) are positively associated with the presence of a band of forested streamside habitat [64].…”

“…They protect water resources through physical and chemical filtration processes, reducing siltation and moderating increases in water temperature [10,58,95]. However, conservation efforts to protect salamander populations in small streams must balance the preservation of riparian buffers with a consideration of the land use throughout the watershed [10,58].…”

“…For instance, riparian forest buffer systems have been used to provide effective control of nonpoint source pollution in certain agricultural watersheds, improving water quality by removing nutrients from runoff and reducing sediment transport [7][8][9]. In addition, riparian zones facilitate the exchange of nutrients between forest and freshwater ecosystems through litter and terrestrial/aquatic insect input and emergence [10,11]. Furthermore, riparian forests are important for recreation, forest products, hunting, fishing, and other human values.…”