, Volume 353, Issue 1-3, pp 63-76

Recovery of three New Zealand rural streams as they pass through native forest remnants

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Abstract

Three small second order streams draining pastoralfarming catchments in the Kaipara region northwest ofAuckland City, New Zealand, were chosen to investigatewhether native forest remnants can restoreforest-stream characteristics to streams in openpasture, and to determine what length the remnantsmust be for this to occur. Changes in physical,chemical and biological characteristics of thestreams, in particular the benthic macroinvertebratecommunity, were measured over distances of up to 600 mfrom the point each stream entered a remnant of nativeforest, and the results compared with those of anundisturbed forested stream.Over 600 m the benthic macroinvertebrate communitychanged from a more enrichment-tolerant to a moreclean-water fauna and became similar to the Controlstream in terms of taxonomic richness andMacroinvertebrate Community Index (MCI). However itstill showed minor effects of enrichment, inparticular elevated overall densities ofinvertebrates. Temperature and dissolved oxygenreturned rapidly (within 300 m) to forest-streamlevels on entering the forest remnant. Nitrate,nitrite, phosphate and suspended solids producedvariable results but there was some evidence ofsignificant instream processing over 600 m.