Asymmetric vegetation responses to mid-Holocene aridity at the prairie-forest ecotone in south-central Minnesota

The mid-Holocene (ca. 8000-4000 cal yr BP) was a time of marked aridity throughout much of Minnesota, and the changes due to mid-Holocene aridity are seen as an analog for future responses to global warming. In this study, we compare the transition into (ca. 9000-7000 yr ago) and out of (ca. 5000-2500 yr ago) the mid-Holocene (MH) period at Kimble Pond and Sharkey Lake, located along the prairie forest ecotone in south-central Minnesota, using high resolution (∼ 5-36 yr) sampling of pollen, charcoal, sediment magnetic and loss-on-ignition properties. Changes in vegetation were asymmetrical with increasing aridity being marked by a pronounced shift from woodland/forest-dominated landscape to a more open mix of grassland and woodland/savanna. In contrast, at the end of the MH, grassland remained an important component of the landscape despite increasing effective moisture, and high charcoal influxes (median 2.7-4.0 vs. 0.6-1.7 mm² cm^− 2 yr^− 1 at start of MH) suggest the role of fire in limiting woodland expansion. Asymmetric vegetation responses, variation among and within proxies, and the near-absence of fire today suggest caution in using changes associated with mid-Holocene aridity at the prairie forest boundary as an analog for future responses to global warming.     

Babbling brook to thunderous torrent: Using sound to monitor river stage

The passive, ambient sound above the water from a river has previously untapped potential for determining flow characteristics such as stage. Measuring sub-aerial sound could provide a new, efficient way to continuously monitor river stage, without the need for in-stream infrastructure. Previous published work has suggested that there might be a relationship between sound and river stage, but the analysis has been restricted to a narrow range of flow conditions and river morphologies. We present a method to determine site suitability and the process of how to record and analyse sound. Data collected along a 500 m length of the River Washburn during July 2019 is used to determine what makes a site suitable for sound monitoring. We found that sound is controlled by roughness elements in the channel, such as a boulder or weir, which influences the sound produced. On the basis of these findings, we collect audio recordings from six sites around the northeast of England, covering a range of flow conditions and different roughness elements, since 2019. We use data from those sites collected during storms Ciara and Dennis to produce a relationship between this sound and river stage. Our analysis has shown a positive relationship between an R² of 0.73 and 0.99 in all rivers, but requires careful site selection and data processing to achieve the best results. We introduce a filter that is capable of isolating a river's sound from other environmental sound. Future work in examining the role of these roughness elements is required to understand the full extent of this technique. By demonstrating that sound can operate as a hydrometric tool, we suggest that sound monitoring could be used to provide cost-effective monitoring devices, either to detect relative change in a river or, after more research, a reliable stage measurement.     

The effects of climate and landscape position on chemical denudation and mineral transformation in the Santa Catalina mountain critical zone observatory

Understanding the interactions of climate, physical erosion, chemical weathering and pedogenic processes is essential when considering the evolution of critical zone systems. Interactions among these components are particularly important to predicting how semiarid landscapes will respond to forecasted changes in precipitation and temperature under future climate change. The primary goal of this study was to understand how climate and landscape structure interact to control chemical denudation and mineral transformation across a range of semiarid ecosystems in southern Arizona. The research was conducted along the steep environmental gradient encompassed by the Santa Catalina Mountains Critical Zone Observatory (SCM-CZO). The gradient is dominated by granitic parent materials and spans significant range in both mean annual temperature (>10 °C) and precipitation (>50 cm a^?1), with concomitant shift in vegetation communities from desert scrub to mixed conifer forest. Regolith profiles were sampled from divergent and convergent landscape positions in five different ecosystems to quantify how climate-landscape position interactions control regolith development. Regolith development was quantified as depth to paralithic contact and degree of chemical weathering and mineral transformation using a combination of quantitative and semi-quantitative X-ray diffraction (XRD) analyses of bulk soils and specific particle size classes. Depth to paralithic contact was found to increase systematically with elevation for divergent positions at approximately 28 cm per 1000 m elevation, but varied inconsistently for convergent positions. The relative differences in depth between convergent and divergent landscape positions was greatest at the low and high elevation sites and is hypothesized to be a product of changes in physical erosion rates across the gradient. Quartz/Plagioclase (Q/P) ratios were used as a general proxy for bulk regolith chemical denudation. Q/P was generally higher in divergent landscape positions compared to the adjacent convergent hollows. Convergent landscape positions appear to be collecting solute-rich soil–waters from divergent positions thereby inhibiting chemical denudation. Clay mineral assemblage of the low elevation sites was dominated by smectite and partially dehydrated halloysite whereas vermiculite and kaolinite were predominant in the high elevation sites. The increased depth to paralithic contact, chemical denudation and mineral transformation are likely functions of greater water availability and increased primary productivity. Landscape position within a given ecosystem exerts strong control on chemical denudation as a result of the redistribution of water and solutes across the landscape surface. The combined data from this research demonstrates a strong interactive control of climate, landscape position and erosion on the development of soil and regolith.     

Closely related thyasirid bivalves associate with multiple symbiont phylotypes

Species of thyasirid bivalves are considered to be representative of early stages of chemosymbiosis, given that bacterial symbionts occur outside gill epithelial cells, vary among species in their abundance and nutritional importance, and are environmentally acquired. For these reasons, assessing the extent of host–symbiont specificity in thyasirids could provide valuable information on the evolution of chemosymbiosis. We show that individuals of two closely related and sympatric Thyasira cf. gouldi operational taxonomic units collected from three sites in a fjord in Newfoundland, Canada, associate with one of three distinct, closely related symbiont phylotypes. While associations show some site‐specificity, there is flexibility in host–symbiont pairings within the fjord, further supporting an early and relatively unspecific stage of chemosymbiosis in this family. Morphologic differences observed both within and among symbiont phylotypes suggest physiologic variation, possibly induced by small‐scale differences in sedimentary conditions.     

Applicability of Individual Transferable Quotas (ITQs) in Japanese fisheries: A comparison of rights-based fisheries management in Iceland, Japan, and United States

ITQs have not yet been introduced by the Government of Japan. In coastal areas, fishery cooperative associations have traditionally played an important role in managing fisheries through self-imposed rules and peer-monitoring systems. Recently, however, the economic competitiveness of Japanese fisheries in the international market is being questioned. In this paper, a detailed examination of the pros and cons of the current system in Japan is compared to the current fishery management measures of Iceland and the United States, where attaining economically or biologically efficient outcomes may be prioritized in making fisheries management decisions. For many coastal fisheries in Japan, maintaining a management scheme in which stakeholders play an active role in determining fisheries measures seems more relevant if their priority is to maintain the stability of coastal communities and equity of stakeholders. Intensive dialog among stakeholders would be necessary to identify shared objectives of their fishery operations and to make decisions to establish specific steps toward the goal of increasing economic efficiency, environmental sustainability, or stability of communities and equity of stakeholders.     

Upwelling in the Alaskan Beaufort Sea: Atmospheric forcing and local versus non-local response

The spin up and relaxation of an autumn upwelling event on the Beaufort slope is investigated using a combination of oceanic and atmospheric data and numerical models. The event occurred in November 2002 and was driven by an Aleutian low storm. The wind field was strongly influenced by the pack-ice distribution, resulting in enhanced winds over the open water of the Chukchi Sea. Flow distortion due to the Brooks mountain range was also evident. Mooring observations east of Barrow Canyon show that the Beaufort shelfbreak jet reversed to the west under strong easterly winds, followed by upwelling of Atlantic Water onto the shelf. After the winds subsided a deep eastward jet of Atlantic Water developed, centered at 250 m depth. An idealized numerical model reproduces these results and suggests that the oceanic response to the local winds is modulated by a propagating signal from the western edge of the storm. The disparity in wave speeds between the sea surface height signal—traveling at the fast barotropic shelf wave speed—versus the interior density signal—traveling at the slow baroclinic wave speed—leads to the deep eastward jet. The broad-scale response to the storm over the Chukchi Sea is investigated using a regional numerical model. The strong gradient in windspeed at the ice edge results in convergence of the offshore Ekman transport, leading to the establishment of an anti-cyclonic gyre in the northern Chukchi Sea. Accordingly, the Chukchi shelfbreak jet accelerates to the east into the wind during the storm, and no upwelling occurs west of Barrow Canyon. Hence the storm response is fundamentally different on the Beaufort slope (upwelling) versus the Chukchi slope (no upwelling). The regional numerical model results are supported by additional mooring data in the Chukchi Sea.     

On the occurrence and origin of anthropogenic radionuclides found in a fragment of the Chelyabinsk (LL5) meteorite

A piece of the 2013 Chelyabinsk meteorite was investigated for its content of anthropogenic radionuclides. In addition to traces of cesium‐137 that had been previously reported for this particular fragment, we found an unusually high amount of strontium‐90, which indicates that the source of this contamination was the Kyshtym accident (1957). A high Sr‐90/Cs‐137 activity ratio is characteristic for Kyshtym‐derived contaminations. Based on the cesium‐137 content in the soil from the finding site, it is estimated that the fragment was contaminated with soil particles in the milligram range upon impact. Investigation of the soil revealed very unusual ferromagnetic characteristics and an iron‐rich chemical composition. Mössbauer spectroscopy indicated the presence of steel components in this soil, suggesting that the investigated meteorite fragment was found in an industrial dumping site rather than natural soil.     

Hyperspectral mapping of alteration assemblages within a hydrothermal vug at the Haughton impact structure,Canada

Meteorite impacts on Earth and Mars can generate hydrothermal systems that alter the primary mineralogies of rocks and provide suitable environments for microbial colonization. We investigate a calcite–marcasite‐bearing vug at the ~23 km diameter Haughton impact structure, Devon Island, Nunavut, Canada, using imaging spectroscopy of the outcrop in the field (0.65–1.1 μm) and samples in the laboratory (0.4–2.5 μm), point spectroscopy (0.35–2.5 μm), major element chemistry, and X‐ray diffraction analyses. The mineral assemblages mapped at the outcrop include marcasite; marcasite with minor gypsum and jarosite; fibroferrite and copiapite with minor gypsum and melanterite; gypsum, Fe³⁺ oxides, and jarosite; and calcite, gypsum, clay, microcline, and quartz. Hyperspectral mapping of alteration phases shows spatial patterns that illuminate changes in alteration conditions and formation of specific mineral phases. Marcasite formed from the postimpact hydrothermal system under reducing conditions, while subsequent weathering oxidized the marcasite at low temperatures and water/rock ratios. The acidic fluids resulting from the oxidation collected on flat‐lying portions of the outcrop, precipitating fibroferrite + copiapite. That assemblage then likely dissolved, and the changing chemistry and pH resulting from interaction with the calcite‐rich host rock formed gypsum‐bearing red coatings. These results have implications for understanding water–rock interactions and habitabilities at this site and on Mars.     

Migrant pathways to resource access in Lampung’s political forest: Gender, citizenship and creative conjugality

An important theme in studies of enclosure and resource access in Southeast Asian hinges on the concept of the ‘political forest’, a particular constellation of power constituted by ideas, practices and institutions that seek to regulate peoples’ access to resources, providing recognition and legitimacy to some, whilst excluding and criminalizing others. Whilst issues of class and ‘race’ underpin work in this vein, in Indonesia, much less attention has been directed towards the ways in which gender inheres in the regularisation of land and livelihood, and the ordering of upland spaces. Drawing on recent feminist and queer theorizing of the links between citizenship, recognition and hetero-normativity, and on analyses of the social relationships through which resource access is negotiated and realized, the paper presents a feminist political ecology of the gender dynamics inherent in the power plays of resource access as land-poor rural migrants negotiate a shifting landscape of enclosure in Lampung province. Through an analysis of three periods of resource governance and control in the province, the paper shows how the negotiation of resource access is simultaneously a process of self-regulation and subject-making that draws on particular ideas about family and conjugal partnership, inculcating gendered and hetero-normative ideologies of the “ideal citizen”. Through particular representational strategies - positionings - necessary to qualify for resource access, and through the material practices necessary to realize the benefits of resource access, conjugal partnership is reiterated and remade as an important social relationship through which resource access may be realised, for men as well as for women.