Riparian Policy Research Articles

Patterns of riparian policy standards in riverscapes of the Oregon Coast Range

Patterns of riparian policy standards in riverscapes of the Oregon Coast Range

Legal ecotones: A comparative analysis of riparian policy protection in the Oregon Coast Range, USA

Waterways of the USA are protected under the public trust doctrine, placing responsibility on the state to safeguard public resources for the benefit of current and future generations. This responsibility has led to the development of management standards for lands adjacent to streams. In the state of Oregon, policy protection for riparian areas varies by ownership (e.g., federal, state, or private), land use (e.g., forest, agriculture, rural residential, or urban) and stream attributes, creating varying standards for riparian land-management practices along the stream corridor. Here, we compare state and federal riparian land-management standards in four major policies that apply to private and public lands in the Oregon Coast Range. We use a standard template to categorize elements of policy protection: (1) the regulatory approach, (2) policy goals, (3) stream attributes, and (4) management standards. All four policies have similar goals for achieving water-quality standards, but differ in their regulatory approach. Plans for agricultural lands rely on outcome-based standards to treat pollution, in contrast with the prescriptive policy approaches for federal, state, and private forest lands, which set specific standards with the intent of preventing pollution. Policies also differ regarding the stream attributes considered when specifying management standards. Across all policies, 25 categories of unique standards are identified. Buffer widths vary from 0 to ∼152 m, with no buffer requirements for streams in agricultural areas or small, non-fish-bearing, seasonal streams on private forest land; narrow buffer requirements for small, non-fish-bearing perennial streams on private forest land (3 m); and the widest buffer requirements for fish-bearing streams on federal land (two site-potential tree-heights, up to an estimated 152 m). Results provide insight into how ecosystem concerns are addressed by variable policy approaches in multi-ownership landscapes, an important consideration to recovery-planning efforts for threatened species.

The surrounding landscape influences the diversity of leaf-litter ants in riparian cloud forest remnants.

Riparian vegetation is a distinctive and ecologically important element of landscapes worldwide. However, the relative influence of the surrounding landscape on the conservation of the biodiversity of riparian remnants in human-modified tropical landscapes is poorly understood. We studied the surrounding landscape to evaluate its influence on leaf-litter-ant alpha and beta diversity in riparian remnants in the tropical montane cloud forest region of central Veracruz, Mexico. Sampling was carried out in 12 sites with riparian vegetation during both rainy (2011) and dry (2012) seasons. Ten leaf-litter samples were collected along a 100-m transect per site and processed with Berlese-Tullgren funnels and Winkler sacks. Using remotely-sensed and ground-collected data, we characterized the landscape around each site according to nine land cover types and computed metrics of landscape composition and configuration. We collected a total of 8,684 ant individuals belonging to 53 species, 22 genera, 11 tribes, and 7 subfamilies. Species richness and the diversity of Shannon and Simpson increased significantly in remnants immersed in landscapes with a high percentage of riparian land cover and a low percentage of land covers with areas reforested with Pinus, cattle pastures, and human settlements and infrastructure. The composition of ant assemblages was a function of the percentage of riparian land cover in the landscape. This study found evidence that leaf-litter ants, a highly specialized guild of arthropods, are mainly impacted by landscape composition and the configuration of the focal remnant. Maintaining or improving the surrounding landscape quality of riparian vegetation remnants can stimulate the movement of biodiversity among forest and riparian remnants and foster the provision of ecosystem services by these ecosystems. Effective outcomes may be achieved by considering scientific knowledge during the early stages of riparian policy formulation, in addition to integrating riparian management strategies with broader environmental planning instruments.

Streamside Policies for Headwater Channels: An Example Considering Debris Flows in the Oregon Coastal Province

Abstract Management policies are increasingly debated for headwater channels given their prevalence and ecological importance in many landscapes. Quantitative differences among headwater channels may offer an objective basis for prioritizing streamside protection. Here, we examine differences among headwater channels as potential transport corridors for debris flows. Specifically, we model differences among hill slopes and headwater channels in probabilities of initiating and being traversed by debris flows that deliver to fish-bearing channels. We develop an approach to rank these probabilities and apply the ranks in delineating alternative streamside management zones. Initiation and traversal probabilities are estimated from an empirically calibrated debris-flow model using regionally available 10-m digital elevation data. Alternatives are delineated by encompassing 25%, 50%, and 75% of debris-flow susceptible hill slopes and headwater channels. Highest initiation and traversal probabilities were contained in a relatively small percentage of the study area. Encompassing lower probabilities required disproportionately larger areas. Substituting delineated alternatives for currently prescribed headwater riparian management zones decreased the total area encompassed on federal lands but increased it on private and state lands. Our intent is not to advocate for any particular alternative but to demonstrate that knowledge about how headwater channels differ over large areas can help tailor riparian policies.