Effects of disturbances on aboveground biomass of alpine meadow in the Yellow River Source Zone, Western China.

A field experiment quantifies the impacts of two external disturbances (mowing-simulated grazing and number of pika) on aboveground biomass (AGB) in the Yellow River Source Zone from 2018 to 2020. AGB was estimated from drone images for 27 plots subject to three levels of each disturbance (none, moderate, and severe). The three mowing severities bear a close relationship with AGB and its annual change. The effects of pika disturbance on AGB change were overwhelmed by the significantly different AGB at different mowing severities (-.471 < r < -.368), but can still be identified by inspecting each mowing intensity (-.884 < r < -.626). The impact of severe mowing on AGB loss was more profound than that of severe pika disturbance in heavily disturbed plots, and the joint effects of both severe disturbances had the most impacts on AGB loss. However, pika disturbance made little difference to AGB change in the moderate and non-mowed plots. Mowing intensity weakens the relationship between pika population and AGB change, but pika disturbance hardly affects the relationship between mowing severity and AGB change. The effects of both disturbances on AGB were further complexified by the change in monthly mean temperature. Results indicate that reducing mowing intensity is more effective than controlling pika population in efforts to achieve sustainable grazing of heavily disturbed grassland.

Things we can do now that we could not do before: Developing and using a cross-scalar, state-wide database to support geomorphologically-informed river management.

A fundamental premise of river management is that practitioners understand the resource they are working with. In river management this requires that baseline information is available on the structure, function, health and trajectory of rivers. Such information provides the basis to contextualise, to plan, to be proactive, to prioritise, to set visions, to set goals and to undertake objective, pragmatic, transparent and evidence-based decision making. In this paper we present the State-wide NSW River Styles database, the largest and most comprehensive dataset of geomorphic river type, condition and recovery potential available in Australia. The database is an Open Access product covering over 216,600 km of stream length in an area of 802,000 km2. The availability of the database presents unprecedented opportunities to systematically consider river management issues at local, catchment, regional and state-wide scales, and appropriately contextualise applications in relation to programs at other scales (e.g. internationally)-something that cannot be achieved independent from, or without, such a database. We present summary findings from the database and demonstrate through use of examples how the database has been used in geomorphologically-informed river management. We also provide a cautionary note on the limitations of the database and expert advice on lessons learnt during its development to aid others who are undertaking similar analyses.

Managing sediment (dis)connectivity in fluvial systems.

Globally, rivers systems are under considerable and increasing threat from multiple anthropogenic stresses, including different types of direct (e.g. channel engineering) and indirect human impacts (e.g. land cover and land use changes) that alter water and sediment dynamics. (Dis)connectivity relationships determine the source, timing and rates of water and sediment flux in catchments and thus their geomorphic sensitivity to disturbance. However, most river and catchment management plans overlook the role of sediment (dis)connectivity. Here we use examples from different environmental settings with different sediment-related problems to show how understandings of sediment (dis)connectivity can inform catchment-based management plans. We focus on concerns for river conservation and recovery, using examples from Austria, New Zealand and Australia. Finally, we present questions for practitioners to consider to appropriately contextualise management applications when using (dis)connectivity concepts in practice. Our findings revealed that differences in sediment (dis)connectivity relationships exert profound catchment-specific variability in (eco)-geomorphic response to disturbance. Understanding (dis)connectivity and system history is therefore essential to forecast the effects of on-ground management actions.

Author Correction: Engaging with research impact assessment for an environmental science case study.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Engaging with research impact assessment for an environmental science case study.

Impact assessment is embedded in many national and international research rating systems. Most applications use the Research Impact Pathway to track inputs, activities, outputs and outcomes of an invention or initiative to assess impact beyond scholarly contributions to an academic research field (i.e., benefits to environment, society, economy and culture). Existing approaches emphasise easy to attribute 'hard' impacts, and fail to include a range of 'soft' impacts that are less easy to attribute, yet are often a dominant part of the impact mix. Here, we develop an inclusive 3-part impact mapping approach. We demonstrate its application using an environmental initiative.

What's in a name? A naming convention for geomorphic river types using the River Styles Framework.

Meaningful iteration between place-based knowledge of rivers and generalised, theoretically-framed understandings is a significant challenge in river science and management. How can we communicate knowledge of the inherent complexity of river systems in light of managerial quests for simple, easy-to-apply frameworks that can be used by a wide range of practitioners, such that we can meaningfully transfer experiences in river science and management from one situation to another? Identification, definition, classification and naming are vital parts of this process. In a sense, a name is like a 'brand', for which a consistency of product is expected. The River Styles Framework is a flexible, open-ended approach to river science and management. The Framework applies a set of hierarchical principles to differentiate reaches, interpret their process-based behaviour and examine interactions between patterns of reaches at the catchment scale. Here we outline an evolution and tightening of the Framework to better communicate how to identify and name types of river at the reach scale. Like the River Styles Framework itself, the naming convention applies hierarchical procedures, starting at the valley setting scale, and incorporating analyses of river planform, channel and floodplain landforms (geomorphic units) and bed material texture. Using a series of examples from around the world, we show how this naming convention can be applied to name river reaches and can be adapted to particular purposes in a consistent, readily communicable manner. We outline various challenges that are faced in managing the use of such a naming convention.

The Blurred Line between Form and Process: A Comparison of Stream Channel Classification Frameworks.

Stream classification provides a means to understand the diversity and distribution of channels and floodplains that occur across a landscape while identifying links between geomorphic form and process. Accordingly, stream classification is frequently employed as a watershed planning, management, and restoration tool. At the same time, there has been intense debate and criticism of particular frameworks, on the grounds that these frameworks classify stream reaches based largely on their physical form, rather than direct measurements of their component hydrogeomorphic processes. Despite this debate surrounding stream classifications, and their ongoing use in watershed management, direct comparisons of channel classification frameworks are rare. Here we implement four stream classification frameworks and explore the degree to which each make inferences about hydrogeomorphic process from channel form within the Middle Fork John Day Basin, a watershed of high conservation interest within the Columbia River Basin, U.S.A. We compare the results of the River Styles Framework, Natural Channel Classification, Rosgen Classification System, and a channel form-based statistical classification at 33 field-monitored sites. We found that the four frameworks consistently classified reach types into similar groups based on each reach or segment's dominant hydrogeomorphic elements. Where classified channel types diverged, differences could be attributed to the (a) spatial scale of input data used, (b) the requisite metrics and their order in completing a framework's decision tree and/or, (c) whether the framework attempts to classify current or historic channel form. Divergence in framework agreement was also observed at reaches where channel planform was decoupled from valley setting. Overall, the relative agreement between frameworks indicates that criticism of individual classifications for their use of form in grouping stream channels may be overstated. These form-based criticisms may also ignore the geomorphic tenet that channel form reflects formative hydrogeomorphic processes across a given landscape.

Quantitative assessment of the relationships among ecological, morphological and aesthetic values in a river rehabilitation initiative.

Promoting community support in rehabilitation efforts through incorporation of aesthetic considerations is an important component of environmental management. This research utilised a small-scale survey methodology to explore relationships among the ecological and morphological goals of scientists and the aesthetic goals of the public using the Twin Streams Catchment, Auckland, New Zealand, as a case study. Analyses using a linear model and a generalised linear mixed model showed statistically significant relationships between perceived naturalness of landscapes and their aesthetic ratings, and among ratings of perceived naturalness and ecological integrity and morphological condition. Expert measures of health and the aesthetic evaluations of the public were well aligned, indicating public preferences for landscapes of high ecological integrity with good morphological condition. Further analysis revealed participants used 'cues to care' to rate naturalness. This suggests that environmental education endeavours could further align values with these cues in efforts to enhance approaches to landscape sustainability.

What are we monitoring and why? Using geomorphic principles to frame eco-hydrological assessments of river condition.

Monitoring and assessment are integral components in adaptive management programmes that strive to improve the condition of river systems. Unfortunately, these procedures are generally applied with an emphasis upon biotic attributes and water quality, with limited regard for the geomorphic structure, function and evolutionary trajectory of a river system. Geomorphic principles convey an understanding of the landscape context within which ecohydrologic processes interact. Collectively, geo-eco-hydrologic understanding presents a coherent biophysical template that can be used to frame spatially and temporally rigorous approaches to monitoring that respect the inherent diversity, variability and complexity of any given river system. This understanding aids the development of management programmes that 'work with nature.' Unless an integrative perspective is used to monitor river condition, conservation and rehabilitation plans are unlikely to reach their true potential.

Don't fight the site: three geomorphic considerations in catchment-scale river rehabilitation planning.

Three geomorphic considerations that underpin the design and implementation of realistic and strategic river conservation and rehabilitation programs that work with the nature are outlined. First, the importance of appreciating the inherent diversity of river forms and processes is discussed. Second, river dynamics are appraised, framing the contemporary behavioral regime of a reach in relation to system evolution to explain changes to river character and behavior over time. Third, the trajectory of a reach is framed in relation to downstream patterns of river types, analyzing landscape connectivity at the catchment scale to interpret geomorphic river recovery potential. The application of these principles is demonstrated using extensive catchment-scale analyses of geomorphic river responses to human disturbance in the Bega and Upper Hunter catchments in southeastern Australia. Differing implications for reach- and catchment-scale rehabilitation planning prompt the imperative that management practices work with nature rather than strive to 'fight the site.'