Implementing an Operational Framework to Develop a Streamflow Duration Assessment Method: A Case Study from the Arid West United States

Streamflow duration information underpins many management decisions. However, hydrologic data are rarely available where needed. Rapid streamflow duration assessment methods (SDAMs) classify reaches based on indicators that are measured in a single brief visit. We evaluated a proposed framework for developing SDAMs to develop an SDAM for the Arid West United States that can classify reaches as perennial, intermittent, or ephemeral. We identified 41 candidate biological, geomorphological, and hydrological indicators of streamflow duration in a literature review, evaluated them for a number of desirable criteria (e.g., defensibility and consistency), and measured 21 of them at 89 reaches with known flow durations. We selected metrics for the SDAM based on their ability to discriminate among flow duration classes in analyses of variance, as well as their importance in a random forest model to predict streamflow duration. This approach resulted in a “beta” SDAM that uses five biological indicators. It could discriminate between ephemeral and non-ephemeral reaches with 81% accuracy, but only 56% accuracy when distinguishing 3 classes. A final method will be developed following expanded data collection. This Arid West study demonstrates the effectiveness of our approach and paves the way for more efficient development of scientifically informed SDAMs.

Producer preferences for drought management strategies in the arid west

This study uses choice experiments to assess fresh produce and hay/forage grower preferred drought management strategies, the level of drought at which growers adopt specific management strategies and the level of drought at which they choose to exit farming in the arid west. Results show preferred strategies differ by drought level and across grower groups. Using logit models, we find that fresh produce growers prefer adopting a water-saving technology (cover crops, manure/mulch application, etc.) and hay/forage growers prefer switching to a more efficient irrigation system. Growers would only exit farming in extreme circumstances such as loss of all water resources. Policies aimed at assisting growers with drought adaptation should focus on preferred strategies to ensure effectiveness. Incentives to offset adoption costs are also recommended. Additionally, growers may benefit from information related to productivity changes under various drought management strategies and drought scenarios.

Prehispanic Highland Textile Technologies: A View from the First Millennium AD at Hualcayán, Ancash, Peru

The exceptional preservation of perishable artifacts on the arid west coast of the Andes has led to an abundance of knowledge on prehispanic textile production. Yet comparatively little of this knowledge is based on highland examples due to their poor preservation in the moist environment of the Andean sierra. Systematic excavations in 2011–2012 at the archaeological complex of Hualcayán in highland Ancash, Peru, revealed surprisingly well-preserved textiles and cordage from four partially looted machay-style tombs. In this article we provide an overview of textile forms, production techniques, and iconography from a sample of 292 textile and cordage fragments, equaling 20% of Hualcayán's assemblage. This work contributes to a better understanding of ancient Andean weaving in general and interregional interaction during the Early Intermediate period and Middle Horizon (ca. AD 1–1000) in particular. Significantly, we document variability in cotton yarn and a general uniformity in camelid yarn and weaving techniques in the overall sample. These findings, in combination with similarities in weaving techniques and style between coastal examples and Hualcayán's fabrics, suggest a coastal–highland relationship.

How to Prioritize Voluntary Dietary Modification

Environmentally motivated voluntary diet modifications are the focus of much research and public discourse. Yet the nuanced multi-faceted, multi-dimensional nature of agriculture-earth interactions, and limited public environmental knowledge likely combine to undermine the efficacy of environmentally motivated dietary shifts, squandering limited good will. To counter this, here I devise two related indices for crudely estimating importance of various environmental impacts of alternative dietary choices. Based on the devised indices (which—coarse, simple and inexhaustive—are best viewed as preliminary assessment) I find that in the U.S., soil conservation and water use in the arid west may well dominate the environmental impacts of food, easily eclipsing greenhouse gas emissions, and that of a limited considered subset of possible dietary shifts, replacing beef with tofu, some legumes, and some cereals are the most beneficial modifications.

Banks Grass Mite (Acari: Tetranychidae) Suppression May Add to the Benefit of Drought-Tolerant Corn Hybrids Exposed to Water Stress

Spider mite (Acari: Tetranychidae) outbreaks are common on corn grown in the arid West. Hot and dry conditions reduce mite development time, increase fecundity, and accelerate egg hatch. Climate change is predicted to increase drought incidents and produce more intense temperature patterns. Together, these environmental shifts may cause more frequent and severe spider mite infestations. Spider mite management is difficult as many commercially available acaricides are ineffective due to the development of resistance traits in field mite populations. Therefore, alternative approaches to suppress outbreaks are critically needed. Drought-tolerant plant hybrids alleviate the challenges of growing crops in water-limited environments; yet, it is unclear if drought-tolerant hybrids exposed to water stress affect mite outbreaks under these conditions. We conducted a greenhouse experiment to evaluate the effect of drought-tolerant corn hybrids on Banks grass mite [Oligonychus pratensis Banks (Acari: Tetranychidae)], a primary pest of corn, under optimal irrigation and water-stress irrigation. This was followed by a 2-yr field study investigating the effect of drought-tolerant corn hybrids exposed to the same irrigation treatments on Banks grass mite artificially infested on hybrids and resident spider mite populations. Results showed that water-stressed drought-tolerant hybrids had significantly lower Banks grass mite and resident spider mite populations than water-stressed drought-susceptible hybrids. Interestingly, water-stressed drought-tolerant hybrids had equal Banks grass mite populations to drought-susceptible and drought-tolerant hybrids under optimal irrigation. We posit that planting drought-tolerant hybrids may suppress spider mite outbreaks in water-challenged areas.

Interannual variability in North American ecosystems

<p>Semi-arid ecosystems have been recognized as an important driver of interannual variability (IAV) in the growth rate of atmospheric CO2. However, the importance of these ecosystems for IAV in gross primary productivity (GPP) and net ecosystem exchange (NEE) over North America is not well characterized. In this study, we examine IAV over temperate North America using NEE constrained by surface-based and space-based atmospheric CO2 measurements over 2010–2015 and upscaled GPP from FluxSat over 2001–2017. We show that the arid west of North America provides a larger contribution to IAV in GPP and NEE than the more productive eastern half of North America. This occurs because flux anomalies in western North America are temporally coherent across the growing season leading to an amplification of GPP and NEE for wet years. In contrast, IAV in eastern North America shows seasonal compensation effects, wherein positive anomalies during April–June are compensated for by negative anomalies during July–September. </p>

Diversity and Multiple Drivers of Pastoral Fulani Migration to Ghana

The relationship between environmental change and migration has generated considerable scholarly debate. In part the literature suggests that climate change in the Sahel is 'forcing' pastoralist groups (mainly Fulani) to migrate to semi-arid West African countries, including Ghana, due to resource scarcity and climatic conditions. Using interviews, focus-group discussions and observations, this article argues that beyond theoretical postulations on resource scarcity and environmentally induced migration, there are multiple drivers that affect diverse migration patterns among Fulani pastoralists in Ghana. This study finds and discusses a range of important drivers of migration, including labour demand for pastoralists, access to pasture, conflict, social networks and peaceful relations.