Factors Influencing the Development of Rangeland Fire Protection Associations: Exploring Fire Mitigation Programs for Rural,Resource-Based Communities

Increases in wildfire frequency and extent in rangelands pose a growing threat to private property and ecosystem health. The state of Idaho, USA, recently promoted rangeland fire protection associations (RFPAs)—nonprofit organizations of local citizens who contribute to firefighting efforts on public rangelands—as one way to mitigate rangeland wildfire risk. This study used in-depth interviews with RFPA members and land management professionals to explore the local circumstances that influenced the establishment and functioning of one RFPA. Results indicate that intergenerational ties to “working the land,” existing reciprocity among neighbors, a culture of self-reliance, and informal social networks all contributed to RFPA formation and functioning. Interaction between RFPA members and professionals improved their relationships and promoted shared understandings about wildfire response. We conclude by discussing conditions that might enable or inhibit RFPAs in other areas and how our findings advance research on adapting mitigation programs to local context.     

Recruitment of Estuarine-Dependent Nekton Through a New Tidal Inlet: the Opening of Packery Channel in Corpus Christi,TX, USA

The US Army Corps of Engineers recently dredged and permanently reopened Packery Channel, historically a natural tidal inlet, to allow water exchange between the Gulf of Mexico and the Laguna Madre, TX, USA. The main objective of this study was to characterize estuarine-dependent recruitment and community structure in seagrass habitats adjacent to Packery Channel pre- and post-channel opening. We sampled fish and crustacean abundance using an epibenthic sled in Halodule wrightii seagrass meadows in both control and impact locations over 2 years, 1 year before the opening of Packery Channel (October 2004–May 2005) and 1 year after (July 2005–April 2006). Using the before–after control–impact design, we found significantly fewer nekton post-channel opening. However, we found significantly higher mean densities of newly settled estuarine-dependent species (Sciaenops ocellatus, Micropogonias undulatus, Lagodon rhomboides, Callinectes sapidus, and penaeid shrimp) post-opening. Multivariate analyses showed significant community assemblage changes post-opening with increased contribution of estuarine-dependent species post-opening. Our results show that estuarine-dependent nekton are using Packery Channel as a means of ingress into areas of the upper Laguna Madre’s seagrass meadows that were previously inaccessible, which may lead to higher fisheries productivity for some of these economically and ecologically important fishery species.     

Is Salinity Variability a Benthic Disturbance in Estuaries?

Freshwater inflow is a driver of the functioning of estuaries, and average salinity is usually measured to identify the effects of inflow in salinity-zone habitats. However, salinity variability could act as a disturbance by producing unstable habitats, leading to the question: is salinity variance an indicator of benthic disturbance, and therefore a driver of community stability? The macrofauna communities of five estuaries that lie in a climatic gradient on the Texas coastline were analyzed using a 26-year data set. Comparisons within and between estuaries with different inflow regimes were used as a natural experiment to simulate press disturbance events (i.e., climatic inflow) and pulse disturbance (i.e., floods) in maintaining community stability. Salinity average and variance was compared with benthic community diversity, evenness, and species richness. Salinity variance was more correlated to benthic diversity for each estuarine system (r?=??0.6610; p?=?0.0015) than average salinity (r?=?0.3818; p?=?0.0967). As salinity variance decreased (i.e., stability increased), diversity levels of benthic communities increased, and areas with mgore freshwater inflow displayed lower levels of benthic diversity. These findings advance a component of the general theory of diversity maintenance that persistent stressors, such as salinity variability, can influence diversity.     

Maintaining grassroots activism: Transition Towns in Aotearoa New Zealand

As a result of burgeoning social and environmental issues, localisation movements such as Transition Towns are emerging. However, tension exists as to the best scale and method to create and maintain this community activism. In this study, we explore the activities of two Transition Towns in Aotearoa New Zealand through a qualitative mixed methodology, and argue that relational notions of scale and the notion of progressive localisms enable an appreciation of the locally rooted but outward looking nature of Transition activities. In turn, this creates space to acknowledge the diffuse nature of change, redefine success and sustain momentum.     

Spatial and temporal replicability of meteoric and in situ 10Be concentrations in fluvial sediment

Cosmogenic isotopes, short‐lived radionuclides, elemental concentrations and thermochronometric indicators are measured in river sand to quantify erosion rates and trace sediment sources, and/or infer erosional processes. Interpretations of detrital sediment analyses are often based on the rarely tested assumption of time‐invariant tracer concentration. A better understanding of when and where this assumption breaks down and what sampling strategies minimize temporal and small‐scale spatial variance will improve science done using detrital river sediment. Here, we present new and previously published spatial and temporal replicates measured for in situ and meteoric ¹⁰Be (¹⁰Be_i and ¹⁰Be_m, respectively). Our new data include 113 replicate pairs, taken from agricultural and/or tectonically active watersheds in China months to millennia apart and spatial replicates taken up to 2 km apart on the same day. The mean percentage difference is 10% (?122% to 150%) for both systems considered together; the mode is close to 0% for both systems; and 36% of pairs of samples replicate within our analytical accuracy at 2σ . We find that ¹⁰Be_i replicates better than ¹⁰Be_m (p < 0.01). ¹⁰Be_i replicability is worse in steeper basins, suggesting that stochastic processes (i.e. landslides) affect reproducibility. ¹⁰Be_m replicability is worse in larger basins, suggesting non‐conservative behavior of ¹⁰Be_m as sediment moves downstream. Our results are consistent with the few previously published replicate studies. Considering all replicate data in a wide range of landscapes, in areas with deep erosional processes, replicability is poor; in other areas, replicability is good. This suggests that, in steep, tectonically active, and/or agricultural landscapes, individual detrital sediment measurements do not represent upstream rates as well as larger populations of samples. To ensure that measurements are representative of the upstream watershed, our data suggest that samples be amalgamated either over time or from several places close by in the same channel. Copyright © 2017 John Wiley & Sons, Ltd.     

Eruptive conditions and depositional processes of Narbona Pass Maar volcano,Navajo volcanic field,Navajo Nation,New Mexico (USA)

Phreatomagmatic deposits at Narbona Pass, a mid-Tertiary maar in the Navajo volcanic field (NVF), New Mexico (USA), were characterized in order to reconstruct the evolution and dynamic conditions of the eruption. Our findings shed light on the temporal evolution of the eruption, dominant depositional mechanisms, influence of liquid water on deposit characteristics, geometry and evolution of the vent, efficiency of fragmentation, and the relative importance of magmatic and external volatiles. The basal deposits form a thick (5–20 m), massive lapilli tuff to tuff-breccia deposit. This is overlain by alternating bedded sequences of symmetrical to antidune cross-stratified tuff and lapilli tuff; and diffusely-stratified, clast-supported, reversely-graded lapilli tuffs that pinch and swell laterally. This sequence is interpreted to reflect an initial vent-clearing phase that produced concentrated pyroclastic density currents, followed by a pulsating eruption that produced multiple density currents with varying particle concentrations and flow conditions to yield the well-stratified deposits. Only minor localized soft-sediment deformation was observed, no accretionary lapilli were found, and grain accretion occurs on the lee side of dunes. This suggests that little to no liquid water existed in the density currents during deposition. Juvenile material is dominantly present as blocky fine ash and finely vesiculated fine to coarse lapilli pumice. This indicates that phreatomagmatic fragmentation was predominant, but also that the magma was volatile-rich and vesiculating at the time of eruption. This is the first study to document a significant magmatic volatile component in an NVF maar-diatreme eruption. The top of the phreatomagmatic sequence abruptly contacts the overlying minette lava flows, indicating no gradual drying-out period between the explosive and effusive phases. The lithology of the accidental clasts is consistent throughout the vertical pyroclastic stratigraphy, suggesting that the diatreme eruption did not penetrate below the base of the uppermost country rock unit, a sandstone aquifer ∼360 m thick. By comparison, other NVF diatremes several tens of kilometers away were excavated to depths of ∼1,000 m beneath the paleosurface (e.g., Delaney PT. Ship Rock, New Mexico: the vent of a violent volcanic eruption. In: Beus SS (ed) Geological society of America Centennial Field Guide, Rocky Mountain Section 2:411–415 (1987)). This can be accounted for by structurally controlled variations in aquifer thickness beneath different regions of the volcanic field. Variations in accidental clast composition and bedding style around the edifice are indicative of a laterally migrating or widening vent that encountered lateral variations in subsurface geology. We offer reasonable evidence that this subsurface lithology controlled the availability of external water to the magma, which in turn controlled characteristics of deposits and their distribution around the vent. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Assessing the role of winter grazing in historic land degradation,Mývatnssveit,northeast Iceland

This paper assesses the contribution of historical and traditional winter grazing to long‐term land degradation in northeast Iceland. To do so, indicators of soil erosion from two contrasting historical winter grazing areas, set in a tephrochronological framework, are compared against their temporal and regional land degradation contexts. The observations made indicate distinctive and different landscape responses to historical winter grazing depending on location. In both study areas, there is an accelerated level of wind and water erosion with settlement at ca. A.D. 874 through to A.D. 1477. One of these areas had a subsequent reduction in erosion rates to considerably below the regional average, possibly as a result of adaptive land management; the second, more inherently sensitive area, is now subarctic desert. These findings confirm early land management practices as a major factor in Icelandic land degradation, they contribute to explanations of early settlement success and failure, and highlight the significance of historical approaches in addressing contemporary issues of land degradation and conservation responses. © 2004 Wiley Periodicals, Inc.