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Subject: search.filters.subject.Riparian ecology

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    The effectiveness of riparian buffer zones for protecting waterways during harvest in the Pipiwai forest in Northland, New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Master of Applied Science in Natural Resource Management, Massey University, Palmerston North, New Zealand
    (Massey University, 2007) Hanmore, Ian
    The harvest of plantation forests has the potential to cause significant negative impacts on the waterways that flow through them. It has been proposed that to mitigate any such impacts waterways should be protected by undisturbed riparian buffer zones (RBZ). As such, this research has been conducted to investigate if RBZs protect plantation waterways during harvest. To do this a case study was carried out in the Pipiwai forest, one of Carter Holt Harvey Forests (CHHF) Northland plantations. In the investigation, 15 first order streams were sampled using an extended version of NIWA's stream health monitoring and assessment kit (SHMAK). The samples were taken from three different stream treatments, those harvested with undisturbed buffers, harvested with no buffers (clearcut) and standing mature pine forest. Each site had the quality of its aquatic and riparian habitats and invertebrate communities assessed via the SHMAK, which presented a rating for each streams health. Statistical analysis was also carried out to determine if any differences in the results were significant or simply an expression of the variation that could be expected in a single population. The management of the plantation was also investigated. CHHF managers were interviewed to determine the activities that could have impacted on the forest's waterways. The results showed that clearcut streams had degraded riparian and aquatic habitats through the loss of vegetation, exposed and eroding soil, and increased streambed sedimentation. This degradation was reflected in the invertebrate communities which were dominated by high numbers of pollutant tolerant species such as mollusks and midges. Buffered waterways, however, had no such degradation and their invertebrate communities had high numbers of pristine requiring invertebrates such as mayflies. Statistical analysis showed that the habitat and invertebrate scores of the clearcut sites were significantly lower than the buffered and pine sites, and it also showed there was no significant difference between the buffered sites and the mature pine sites. The results also showed that the management of the Pipiwai plantation was conducted to industry and council standards, but that this was insufficient to prevent the degradation of the waterways in the clearcut catchments. The two main conclusions of this research were that RBZs in the Pipiwai forest protected waterways from degradation during plantation harvest and maintained them in a state similar to that of standing mature pine forest, and that management practices and regulations in use at the time of harvest, though within industry and government standards, were unable to prevent waterway degradation and achieve results equal to those of the RBZs.
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    An evaluation of the ecology and riparian management of the south branch of the Whareroa Stream, Paekakariki : a thesis presented in partial fulfilment of the requirements for the degree of Master of Applied Science in Natural Resource Management at Massey University
    (Massey University, 2008) Palmer, Karen Thelma
    Whareroa Farm, Mackays Crossing, Paekakariki, was bought by the Department of Conservation in 2005. The goal was to effect the restoration of a corridor for flora and fauna from the Akatarawa Forest in the east to Queen Elizabeth Park and the sea in the west. The south branch of the Whareroa Stream, which arises as a series of tributaries from a ridge 272m above sea level, traverses Whareroa Farm and the adjacent Queen Elizabeth Park. It was thought likely that the stream had been severely affected ecologically during a century of cattle and sheep farming, though the degree to which the ecological degradation had occurred was unknown. Obvious deforestation and land use changes suggested that, in concert with many other New Zealand hill country farms, the ecological changes would be significant. To establish and quantify the degree of degradation, the Auckland Regional Council (ARC) Stream Environment Valuation (SEV) protocol was applied to the Whareroa Stream and its tributaries. Five sites were selected for valuation, varying from open pasture to bush covered and open parkland. The resulting SEV scores showed losses of ecological value ranging from 32% to 46% across the sites. The Macroinvertebrate Community Index (MCI) and the fish Index of Biological Integrity (IBI) were measured at each site. Results indicated that aquatic habitats were unable to sustain adequate assemblages at four of the five sites. The valuations of the riparian zones at each site used the River Environment Classification (REC) and Riparian Management Classification (RMC) protocols. The results indicated that current riparian characteristics showed poor to absent effective riparian zones from the headwaters to the sea at all sites. Riparian zones are pivotal to the provision of stream ecological integrity and are responsible for maintaining the longitudinal, lateral and vertical connectivity between a stream, its network and its surrounding land. The loss of in-stream organic matter from lack of riparian vegetation together with the loss of effective temperature control from lack of shade, impacts negatively on the habitats for macroinvertebrates and fish. This was highlighted in the Whareroa Stream network. While the SEV and RMC evaluations showed that, with best practice management plans, there was great potential for improvement of the Whareroa Stream ecology, any riparian restoration would require sympathetic and improved fencing, withdrawal of stock from stream access and the retirement of headwater land from pastoral use. The loss of ecological integrity that occurs as a result of prolonged land use changes from forest to agriculture is well illustrated by the situation in the south branch of the Whareroa Stream and its tributaries.