Challenges in applying scientific evidence to width recommendations for riparian management in agricultural Australia
- Authors: Hansen, Birgita , Reich, Paul , Cavagnaro, Timothy , Lake, Philip
- Date: 2015
- Type: Text , Journal article
- Relation: Ecological Management and Restoration Vol. 16, no. 1 (2015), p. 50-57
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- Reviewed:
- Description: Intact riparian zones maintain aquatic-terrestrial ecosystem function and ultimately, waterway health. Effective riparian management is a major step towards improving the condition of waterways and usually involves the creation of a 'buffer' by fencing off the stream and planting vegetation. Determination of buffer widths often reflects logistical constraints (e.g. private land ownership, existing infrastructure) of riparian and adjacent areas, rather than relying on rigorous science. We used published information to support riparian width recommendations for waterways in agricultural Victoria, Australia. We focused on different ecological management objectives (e.g. nutrient reduction or erosion control) and scrutinised the applicability of data across different environmental contexts (e.g. adjacent land use or geomorphology). Not surprisingly, the evidence supported variable 'effective' riparian widths, depending on the objective and environmental context. We used this information to develop a framework for determining riparian buffer widths to meet a variety of ecological objectives in south-east Australia. Widths for reducing nutrient inputs to waterways were most strongly supported with quantitative evidence and varied between 20 and 38 m depending on environmental context. The environmental context was inconsistently reported, making it difficult to recommend appropriate widths, under different land-use and physiographic scenarios. The evidence to guide width determination generally had high levels of uncertainty. Despite the considerable amount of published riparian research, there was insufficient evidence to demonstrate that implemented widths achieved ecological objectives. We emphasise the need for managers to clearly articulate the objectives of proposed riparian management and carefully consider the environmental context. Monitoring ecological responses associated with different riparian buffer widths is essential to support future management decisions.
Livestock grazing effects on riparian bird breeding behaviour in agricultural landscapes
- Authors: Hansen, Birgita , Fraser, Hannah , Jones, Christopher
- Date: 2019
- Type: Text , Journal article
- Relation: Agriculture, Ecosystems and Environment Vol. 270-271, no. (2019), p. 93-102
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- Reviewed:
- Description: Globally, many bird species that rely on native woodland or forest environments are declining due to vegetation clearing for livestock pastures and cereal cropping. In many landscapes, woodland remnants are restricted to waterways and roadsides in narrow, sometimes degraded patches, and not all patches can necessarily provide the resources required to support bird populations. This study investigated the influence of livestock grazing and vegetation characteristics on bird breeding activity in riparian zones in northern Victoria, Australia, where much of the landscape is used for production and has experienced significant loss of woodland. Birds were broadly categorised as ‘woodland’ or ‘non-woodland’ species, based on dependency on woodlands for breeding. The majority of woodland species detected were relatively common, and where riparian zones were heavily grazed, there was significantly lower woodland bird breeding activity compared to non-woodland bird breeding activity (the latter increasing with grazing intensity). Woodland and non-woodland birds had consistently opposite responses to grazing intensity, vegetation and landscape characteristics, suggesting that the factors influencing breeding differ markedly between these two groups. Thus, where riparian zones are intensively grazed, the bird community shifts from predominantly woodland to largely non-woodland species. This has implications for the conservation of both rare and common woodland bird species in southern Australia. Simple changes in land management, for example, livestock exclusion from important breeding habitat, may confer large gains for population persistence of woodland bird species.