Riparian Zone Management Research Articles

Fluvially-deposited large wood and riparian plant diversity

Out-of-channel wood jams centred by fluvially-deposited large wood represent an important habitat for riparian plant species along large rivers dominated by exposed riverine sediments. Such wood jams often display distinct physical features associated with the jams, such as areas of scour immediately upstream, plumes of fine sediment downstream and abundant organic material deposited throughout the jam. This paper examines the relationship between physical characteristics of young wood jams (1–3 years since deposition) and riparian plant diversity along the braided River Tagliamento in Northeast Italy. Species richness of riparian plants was significantly positively correlated to the depth of scour features and amount of fine sediment around the wood jams, which facilitate improved access to the water table and increase available water in the sediments, respectively. Species diversity was significantly positively correlated to scour pool depth only. Scour depth was in turn influenced by wood jam size, indicating that larger jams may indirectly increase riparian plant diversity. Management and restoration of riparian zones containing exposed riverine sediments should allow for the formation of wood jams and their associated features where possible, in order to potentially increase localised biodiversity.

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.

Priority environmental issues for monitoring - mismatch between farmers and catchment management perspectives

Monitoring is an essential part of an environmental management system (EMS) if landholders are to demonstrate improved environmental performance. This paper reports results of two surveys to determine environmental issues and priorities for monitoring. The first survey was conducted on 12 EMS pilot projects, and the second on 18 catchment management organisations in Australia. With the exception of pastoral zones, EMS facilitators identified moderate to major issues in land condition, water balance, riparian zone, native vegetation condition and pests. Water quality issues were rated as minor to moderate problems. Issues raised by the greatest number of respondents were water balance problems and weed and pest issues. Catchment managers reported widespread degradation issues in land condition, water balance problems, altered water flow, water quantity and availability and water quality. Degradation of the riparian zone and native vegetation were also reported. Both EMS facilitators and catchment management organisations understood the need for environmental monitoring; however, few EMS pilot projects have addressed it. This was due, in part, to a lack of readily available tools and concentration on the EMS process itself. Tools of most interest to facilitators were soil erosion risk, soil test interpretation, soil structure assessment, soil health, water leakage and perenniality, water quality, riparian zone management, herbicide resistance, greenhouse emissions and energy use. Facilitators also suggested that tools should be delivered in several formats, but workshops delivered by experts were of most interest. Catchment managers had realistic and pragmatic views about the role of landholder monitoring in assessing catchment outcomes and there is a mismatch between landholder monitoring and catchment reporting requirements. Landholders are likely to monitor only what is in their direct interests and this will be mainly on land condition. We conclude that on-farm environmental monitoring conducted by landholders will be of limited use for catchment management organisation reporting. However, it will be very important in helping farmers to make more informed decisions about their environmental management, together with education and support. The issue of catchment condition monitoring and reporting requires serious attention as current monitoring and reporting is likely to be inadequate.

Landscape hierarchies influence riparian ground-flora communities in Wisconsin, USA

We examined the distribution of ground-flora species (herbaceous and woody species <1 m tall) across riparian areas of northeastern Wisconsin in an effort to understand how hierarchical landscape properties, such as the physiographic system (ground moraine and outwash plain), valley system (constrained and unconstrained), and valley floor landforms influence distribution patterns of ground-flora species and functional plant guilds across riparian areas of small streams and rivers in a glacial landscape. A total of 162 species were recorded on 417 (1 m 2) plots stratified by four different valley types that reflect the dominant physiographic system and valley system (constrained ground moraine, constrained outwash plain, unconstrained ground moraine, unconstrained outwash plain) and transverse geomorphic structure (valley floor landforms including floodplains, terraces, slopes, and adjacent uplands). Although distribution patterns of individual ground-flora species are highly variable among the four valley types, canonical correspondence analyses (CCA) of individual valley types indicate that ground-flora vegetation is related strongly to hierarchical landscape properties, including valley type and the transverse geomorphic structure of the stream valley. Vegetation ultimately reflects the influence of hydrogeomorphic processes that shape valley floor landforms. Constrained valley types tend to be characterized by diverse floodplain ground-flora communities dominated by graminoids and pteridophytes, while the terraces and slope plant communities are comprised of facultative upland and obligate upland perennial forb and woody species whose distribution appears to be a function of topographic features, such as aspect. However, ground-flora communities of unconstrained valley types appear to be responding not only to changes associated with the transverse geomorphic structure of the riparian ecotone, but also to more localized changes in environmental conditions associated with flooding and hydrologic regime. As a result, floodplain, terrace, and slope ground-flora communities tend to be diverse, dominated by a mixture of obligate wetland, facultative wetland, and facultative species. Thus, variation in riparian plant community characteristics can be explained using a nested, hierarchical landscape framework to organize and group different riparian settings based on the underlying geomorphic processes shaping stream valleys. Based on these results, we suggest that riparian management zones (RMZs) designed to maintain riparian function should be variable in width rather than fixed, encompassing variation in valley floor landforms and valley walls, regardless of the physiographic system.

Water quality protection in bioenergy production: the US system of forestry Best Management Practices

United States federal law requires that states operate programs to address non-point source pollution. Forestry non-point source programs vary among states in their approach. Some states have laws that prescribe mandatory practices to control pollution, whereas other states use voluntary approaches of Best Management Practices (BMPs) and education and outreach programs. States routinely monitor the extent of BMP implementation so as to improve educational programs and thus improve implementation. Many states also have conducted studies to assess whether BMPs are effective in protecting water quality. A growing body of literature strongly suggests that properly implemented BMPs do protect water quality. A variety of private efforts, ranging from forestry certification systems to research support, are improving BMP implementation and effectiveness. BMPs developed for conventional forestry should be applicable to bioenergy systems. Bioenergy systems may include more frequent fertilization than conventional forestry, so managers must ensure that existing BMPs on fertilization and riparian management zones be fully implemented. Bioenergy systems using short-rotation woody crops will need careful implementation of BMPs for permanent roads and stream crossings.

ESTIMATING AREAS AND TIMBER VALUES OF RIPARIAN MANAGEMENT ON FOREST LANDS1

ABSTRACT:Buffers, filter strips, and other riparian protection zones are widely accepted practices used to minimize water quality impacts from forest management and other land use activities. Riparian management prescriptions are often developed with limited or inconsistent consideration of the impact they will have on land management opportunities or economics. A combination of factors influences the area and value of riparian management zones (RMZs). A simple tool can determine the percentage of a watershed in RMZs where they comprise only a small fraction of the watershed. For a more detailed analysis, the Oak Creek Watershed in Oregon served as an example of a geographic information system (GIS) assessment. The same watershed can have dramatically different areas and values of timber in RMZs depending on the resolution used to determine the stream network, different stream types (perennial fish‐bearing, perennial nonfish bearing, and nonperennial; small, medium, and large), and different RMZ widths and management restrictions for each stream type. The areas of watershed put into riparian protection for two drainage densities and three RMZ prescriptions were determined. Finally, the volumes of merchantable timber in the RMZs and their subsequent values were determined.

Explaining landholders' decisions about riparian zone management: The role of behavioural, normative, and control beliefs

Water quality is a key concern in the current global environment, with the need to promote practices that help to protect water quality, such as riparian zone management, being paramount. The present study used the theory of planned behaviour as a framework for understanding how beliefs influence decisions about riparian zone management. Respondents completed a survey that assessed their behavioural, normative, and control beliefs in relation to intentions to manage riparian zones on their property. The results of the study showed that, overall, landholders with strong intentions to manage their riparian zones differed significantly in terms of their beliefs compared to landholders who had weak intentions to manage their riparian zones. Strong intentions to manage riparian zones were associated with a favourable cost–benefit analysis, greater perceptions of normative support for the practice and lower perceptions of the extent to which barriers would impede management of riparian zones. It was also evident that willingness to comply with the recommendations of salient referents, beliefs about the benefits of riparian zone management and perceptions of the extent to which barriers would impede riparian zone management were most important for determining intentions to manage riparian zones. Implications for policy and extension practice are discussed.

SPATIOTEMPORAL RESPONSES OF REPTILES AND AMPHIBIANS TO TIMBER HARVEST TREATMENTS

We compared the influence of clearcut and selective timber harvest treatments on spatial and temporal variability of amphibians and reptiles in an east Texas bottomland hardwood forest. The dataset represented a time series of 5 years post-treatment. A total of 18,645 amphibians and reptiles was captured in 144 pitfall arrays. We used 9 plots (3 clearcut, 3 select cut, and 3 untreated). Each plot had 16 arrays and was bisected by 1 of 3 streams. Pitfall captures represented 46 species (16 amphibians, 30 reptiles). When analyzed with a traditional ANOVA approach, these data suggested an increase in reptile species richness in response to clearcut treatments; amphibian species richness did not respond to treatment. When analyzed as a time series, however, the data revealed fluctuations in site use by species and species groups, and these fluctuations were independent of treatment effects. Exploratory analyses of spatio-temporal dynamics showed that species richness and the relative abundance of common species displayed spatial patterns that remained consistent over time. In control and select cut treatments, spatial patterns of richness and abundance shifted over time and were not necessarily confined to areas adjacent to streams. In clearcuts, stationary habitat refugia were located within riparian management zones.

水辺管理区域の現況とその保全が林業に及ぼす影響―岩手山周辺地域を事例として―

数値地図,現存植生図,森林資源GISデータ等を用いて岩手山周辺地域の植生状況と水辺管理区域(RMZ)の施業規制が木材生産に及ぼす影響を分析した。RMZは,永久河川•湖沼からのバッファリングによって設定した。RMZの占める面積割合は,その幅15mでは4%,50mでは11%に達した。森林区域以外のRMZでは,森林はわずかであることから,水辺林回復が必要である。一方,森林区域のRMZでは,人工林率は少ないが,民有林では高齢林が少なく,保全の必要がある。また,RMZを含む林分は,出材しやすい場所が多く,民有林の林分は高い割合でRMZに包含された。現状の規制は緩く,RMZを禁伐とした場合の補償額は,幅を広くとるほど高額となる。他方,小面積林分を規制対象から除外すると,保全されるべきRMZが断片化した。以上から,個人有林等に対してはRMZの幅を小さくし,施業要件を緩和する等の措置が適当と考えられる。

Forestry and the aquatic environment: studies in an Irish context

Abstract. Research on the interaction between plantation forestry and aquatic environments is essential to develop environmentally compatible and sustainable management further. Given, in Ireland, the generally low levels of atmospheric pollution, its geology and maritime climate, and the unique fauna and flora due to its island history, such studies are important not only in the regional context, but also internationally, as they provide an opportunity to examine the effect of forestry and forest management practices on aquatic systems per se, without the complications of acidification. Here, some of the major findings of forestry and water research in Ireland have been reviewed and compared with those from the UK and elsewhere. Plantation forests do not exacerbate acidification in the south of Ireland (Munster) as a whole so that the influence of forestry on water chemistry is far less important than in other parts of the country (such as Wicklow and Mayo). The main forestry influence on streams in Munster is more likely through physical factors, but their nature is unclear. In a few catchments some negative effects are evident, but in many others apparently positive forest effects occur. In this context, smaller scale catchment-level effects appear to be more important in explaining the various relationships between plantation forests and stream ecology than larger scale regional factors. The management of riparian zones, particularly in forested catchments, is of major importance for the structure and functioning of aquatic communities and further work is needed on best management practices. It is suggested that it is unreasonable to base forest management on national Forest-Fisheries guidelines since regions vary too much and the signal from local conditions is too strong. The approach for environmentally benign, scientifically sound forestry management has to be at the catchment scale. Trees in the right places may be beneficial ecologically but further work is needed to identify these locations. The introduction of new forest management practices such as adoption of new species mixes and continuous forest cover are at an early stage in Ireland and their influence on aquatic systems is unknown. Keywords: forest-stream interactions, Irish plantation forestry, hydrochemistry, macroinvertebrates, salmonids, forest management

Riparian Management Practices in the Eastern U.S.: A Summary of State Timber Harvesting Guidelines

States develop guidelines to protect and manage forest riparian resources. A review of 37 eastern states' forest riparian guidelines (e.g., BMPs, regulations) for timber harvesting revealed the primary focus is water quality protection adjacent to perennial and intermittent streams and lakes. A commonly recommended riparian management zone is 50-foot wide with 50–75 percent crown closure (or 50–75 ft2/acre of residual basal area), although the specific guidelines in each state vary tremendously. Additional values which increase the width of the riparian management zone are based on: (1) waterbody size, (2) slope of the ground adjacent to the waterbody, or (3) by incorporating slope effects with waterbody size or soil erodibility. While science cannot specify the management prescriptions needed to protect all riparian functions across all sites, understanding site-specific conditions can facilitate effective guideline implementation. There is a need for additional research within these areas to address a variety of questions.

A Case Study on Rotational Grazing and Riparian Zone Management: Implications for Producers and a Conservation Agency

A Case Study on Rotational Grazing and Riparian Zone Management: Implications for Producers and a Conservation Agency

PLANT DIVERSITY CONTRIBUTIONS OF RIPARIAN AREAS IN WATERSHEDS OF THE NORTHERN LAKE STATES, USA

In most forested watersheds, riparian areas constitute a small proportion of the total land area, yet their contributions to overall plant diversity can be significant. However, little information is available on which portion of riparian areas (defined as functional ecotones comprising all fluvial landforms, including floodplains, terraces, and connecting hillslopes) contribute the most to plant species richness and at what scale these contributions are most evident. In order to better understand the contributions riparian areas provide to plant species richness in forested watersheds, we examined herbaceous ground‐flora richness and similarity from 56 reaches in eight different valley types (defined as unique combinations of stream order, surficial geology, and stream‐valley constraint) across the northern Lake States, USA. We analyzed these data at two scales: (1) at the individual reach scale; and (2) at the watershed scale by pooling individual reaches by valley type. At the reach scale and regardless of valley type, there is not significant (&lt;50%) species similarity among landforms; however, levels of species richness are not significantly different among the floodplain, terrace–slope complex landforms (e.g., terraces, connecting hillslopes), and adjacent uplands. This suggests that individual reaches (representing an individual riparian area) may not provide significant contributions to overall plant species richness. However, when individual reaches are pooled by valley type, the floodplains are almost always more species rich than the terrace–slope complex and upland landforms, suggesting that the environmental heterogeneity associated with a variety of individual reaches can be responsible for greater species richness provided by riparian areas at the watershed level. Our results also suggest that floodplains are not the only riparian landform that adds significantly to the overall plant diversity of watersheds, especially in areas with broad, unconstrained valleys. In these systems, the terrace–slope complex landforms comprising a series of broad fluvial terraces and connecting slopes have significantly higher species richness than the adjacent uplands. Consequently, it is apparent that, to maintain plant diversity at both local and regional levels, efforts should focus on all fluvial landforms of the riparian area, not just their floodplains. This is particularly relevant when management of riparian areas uses fixed‐width riparian management zones (RMZs). In our study areas, 33 m‐wide RMZs (the recommended width in each of our study states) often failed to include fluvial landforms beyond the floodplain. The consequence is that areas of increased species richness and/or unique plant assemblages in the watershed may receive inadequate protection during forest‐management operations.

British Columbia's Environmental Forestry Policy Record in Perspective

Abstract Some environmental groups and US forest companies, each for their own reasons, have criticized forest policy in British Columbia as lax, and the US Congress and media have taken up the call for stricter regulations in Canada. A comparison of BC forest policy with the policies of the USDA Forest Service and six major softwood-harvesting states reveals that British Columbia has more stringent regulations than has been supposed. Focusing on clearcutting, riparian zone management, and protected areas, we find that BC policy in spring 2001 was generally comparable to that of Washington State and Oregon; only the Forest Service had stricter rules. State practices in Texas, Alabama, Mississippi, and Georgia were less stringent.

IMPLICATIONS OF RIPARIAN MANAGEMENT STRATEGIES ON WOOD IN STREAMS OF THE PACIFIC NORTHWEST

Riparian forest management plans for numerous regions throughout the world must consider long‐term supply of wood to streams. The simulation model OSU STREAMWOOD was used to evaluate the potential effects of riparian management scenarios on the standing stock of wood in a hypothetical stream in the Pacific Northwest, USA. OSU STREAMWOOD simulates riparian forest growth, tree entry (including breakage), and in‐channel processes (log breakage, movement, and decomposition). Results of three simulation scenarios are reported. The first scenario assessed total wood volume in the channel from Douglas‐fir plantations clearcut to the stream bank using three rotation periods (60, 90, and 120 yr). Without a forested riparian management zone, accumulation of wood in the channel was minimal and did not increase through time. In the second scenario, response of total wood volume to forested riparian management zones of widths between 6 m and 75 m was evaluated. Total wood volume associated with the 6 m wide nonharvested forest for forest ages ≥240 yr was 32% of the standing stock associated with a nonharvested forest buffer one potential tree height in width. Maximum standing stock associated with the channel for nonharvested riparian forests ≥30 m required 500‐yr‐old forests. In the third scenario, contribution of wood from forest plantations beyond nonharvested forests of various widths was explored. Forest plantations associated with nonharvested riparian buffers with widths &gt;10 m contributed minimal amounts of wood volume to the stream. These results suggest that forest age and width of the nonharvested buffers are more important than the rotation age of plantation forests in providing long‐term supplies of wood to streams.

Aspen Regeneration in Riparian Management Zones in Northern Minnesota: Effects of Residual Overstory and Harvest Method

Abstract We examined aspen regeneration under different riparian management zone (RMZ) treatments in aspen forests in northern Minnesota. We also compared aspen regeneration in partially harvested RMZs to adjacent upland clearcuts. The four RMZ treatments included: (1) full control (no cutting in RMZ or upland; (2) riparian control (RMZ uncut; upland clearcut); and partially harvested RMZs cut to 54 ft2/ac, with upland clearcut using (3) cut-to-length (CTL), or (4) tree-length harvesting. Three years after harvest, aspen sucker densities in the tree-length and CTL treatments were significantly higher than the full control, but did not differ from each other or the riparian control. Mean individual sucker heights (63–73 in) and aboveground biomass (2.4–3.4 oz) varied among the riparian treatments, but not significantly. Sucker densities were 62% higher in the adjacent clearcuts than in the partially harvested RMZs. Mean suckers heights did not differ between the two locations (71 in.), but aboveground biomass of suckers did differ significantly, averaging 3.4 oz in the partially harvested RMZs and 4.5 oz in the clearcuts. Our results indicate that 60% removal of basal area within RMZs increases density and size of aspen regeneration significantly, compared to uncut forest, but stocking is still below what is considered adequate for 3-yr-old stands. Suckering responses were similar with cut-to-length and tree-length harvesting, suggesting that harvest system has little effect on sucker development. While aspen likely will be a component of partially harvested RMZs, density and biomass increment will be much lower than in single-cohort stands and lower than what is considered desirable for commercial production. North. J. Appl. For. 20(2):79–84.

Policy tools to encourage the application of sustainable timber harvesting practices in the United States and Canada

States and provinces of the United States and Canada have defined practices to mitigate the negative externalities often associated with timber harvesting activities. This paper describes the various methods states and provinces employ to encourage the application of sustainable timber harvesting practices. Information on specific policy tools used to encourage guideline application was obtained through a written questionnaire to state and provincial forestry agency directors. All but one of the 51 responding states and provinces have some form of formally-defined timber harvesting practices. Practices that address riparian zone management, water quality, or wetlands protection are the most common—all but one responding state and province addresses one of more of these areas. Sixty-one percent of the states and provinces implement their practices through predominantly voluntary means whereas the remaining 39% are applied within a regulatory framework. Of the policy tools examined, technical assistance, educational, and cost-share programs account for 88% of all state and provincial programs directed at encouraging forest landowners to use the practices suggested in their guidebooks. Technical assistance and education programs are the most common policy tools used to assist loggers and foresters in applying sustainable harvesting practices. Technical assistance and cost-share programs consistently rank among the most effective policy tools for encouraging loggers, landowners, and foresters to apply the sustainable timber harvesting practices. Comparing levels of program investment to perceived benefits, assistance programs and education programs rank most efficient for landowners and foresters, respectively. Premium prices for products and preferential access to contracts are the two most efficient programs directed at loggers, yet their existence is modest within states and provinces. The paper concludes with an assessment of emerging trends and additional information needs associated with encouraging the application of sustainable timber harvesting practices.

CHANNEL RESPONSE FROM SHRUB DOMINATED RIPARIAN COMMUNITIES AND ASSOCIATED EFFECTS ON SALMONTD HABITAT1

ABSTRACT: We surveyed first‐to third‐order streams (channel widths from 1.4 to 10 m) in the southeastern slopes of the Cascade Range of Washington and found two distinct endpoints of riparian vegetation. Where the forest overstory is dominated by park‐like Ponderosa pine (Pinus ponderosa), channels are commonly bordered with a dense scrub‐shrub vegetation community. Where fire suppression and/or lack of active riparian zone management have resulted in dense encroachment of fir forests that create closed forest canopies over the channel, scrub‐shrub vegetation communities are virtually absent near the channel. Other factors being equal, distinct differences in channel morphology exist in streams flowing thru each riparian community. The scrub‐shrub channels have more box‐like cross‐sections, lower width‐to‐depth ratios, more pools, more undercut banks, more common sand‐dominated substrates, and similar amounts of woody debris (despite lower tree density). Temperature comparisons of forest and scrub‐shrub sections of two streams indicate that summer water temperatures are slightly lower in the scrub‐shrub streams. We surmise that these morphology and temperature effects are driven by differences in root density and canopy conditions that alter dynamic channel processes between each riparian community. We suspect that the scrub‐shrub community was more common in the landscape prior to the 20th century and may have been the dominant native riparian community for these stream types. We therefore suggest that managing these streams for dense riparian conifer does not mimic natural conditions, nor does it provide superior in‐stream habitat.

RIPARIAN ZONE CLASSIFICATION FOR MANAGEMENT OF STREAM WATER QUALITY AND ECOSYSTEM HEALTH1

ABSTRACT: Riparian zones perform a variety of biophysical functions that can be managed to reduce the effects of land use on instream habitat and water quality. However, the functions and human uses of riparian zones vary with biophysical factors such as landform, vegetation, and position along the stream continuum. These variations mean that “one size fits all” approaches to riparian management can be ineffective for reducing land use impacts. Thus riparian management planning at the watershed scale requires a framework that can consider spatial differences in riparian functions and human uses We describe a pilot riparian zone classification developed to provide such a framework for riparian management in two diverse river systems in the Waikato region of New Zealand. Ten classes of riparian zones were identified that differed sufficiently in their biophysical features to require different management. Generic “first steps” and “best practical” riparian management recommendations and associated costs were developed for each riparian class. The classification aims to not only improve our understanding of the effectiveness of riparian zone management as a watershed management tool among water managers and land owners, but to also provide a basis for deciding on management actions.

Riparian Management Practices: A Summary of State Guidelines

Abstract Individual states develop guidelines to protect and manage forest riparian resources. A review of 49 states' forest riparian guidelines revealed the primary focus is to protect the quality of water adjacent to perennial and intermittent streams and lakes. A commonly recommended riparian management zone is 50 feet wide with 50 to 75 percent crown closure (or 50–75 square feet per acre of residual basal area); however, the specific guidelines in each state vary tremendously. Although science cannot specify the management prescriptions needed to protect all riparian functions across all sites, understanding site-specific conditions is critical to effective guideline implementation.