Southwestern Portion Research Articles

Home range and movements of San Joaquin antelope squirrels in the San Joaquin Desert of California

The San Joaquin antelope squirrel (Ammospermophilus nelsoni) is one of five species in the genus and has the most restricted range of the four mainland antelope squirrels, occurring only in the San Joaquin Desert of California. Despite being state-listed as Threatened since 1980, few studies have been conducted on A. nelsoni, especially ecological studies, which hampers recovery efforts. We conducted a radio-telemetry study in 2002 of 19 males on the Lokern Natural Area in the southwestern portion of the San Joaquin Desert. Based on 100% Minimum Convex Polygons (MCP), home ranges varied from 1.25–14.5 ha with a mean of 5.93 ha (± 0.90 standard error). The average daily distance traveled by these 19 males was 128.5 m (range, 71.4–224.5) and the average greatest distance travelled in a day was 313.0 m, with some traveling > 0.5 km. Our data are useful to further refine the estimates of home range and movements of this neglected protected species, but in the future, better home range studies are needed that span multiple years, include both sexes, and occur at sites across its range.

Distribution of crayfish in the Southern Basin of Lake Michigan and the Greater Chicago Region

Crayfish represent important links in aquatic food webs because they have diverse, omnivorous diets and are an important source of energy for fishes and birds. Crayfish have the ability to increase sediment transport through bioturbation, some are considered ecosystem engineers due to their burrowing habits, and crayfish invasions have been linked to large declines in biodiversity and changes in ecosystem structure and function. Despite their ecological importance and the threats that invasive crayfishes pose, the distribution of crayfishes in the Laurentian Great Lakes is not well studied. Here, we report on four years of intensive crayfish surveys in the southwestern portion of the Lake Michigan Basin, a region with diverse freshwater ecosystems and few previous records of crayfish distribution. From 2015 to 2018, baited minnow traps and SCUBA were used to document the distribution and abundance of crayfish across streams, rivers, inland lakes, and Lake Michigan. Six species of crayfish were captured, including two invasive species. The invaders are the widely distributed and abundant Faxonius rusticus (rusty crayfish) and Procambarus clarkii (red Swamp crayfish), a species early in the invasion phase. Native species were found in fewer habitat types and were less abundant than invasive F. rusticus. Comparing our results to previous sampling showed that native crayfish distribution and diversity have declined at the same time that F. rusticus has spread over recent decades. There is potential for new and recently introduced invaders, such as the red swamp crayfish, to further alter ecosystems.

Delineation of Basin Geometry within Parts of Northern Anambra Basin, Nigeria: An Aeromagnetic Approach

Total field aeromagnetic anomalies over Ankpa and environs Northern Anambra basin (sheets 269, 270,288 and 289) were acquired, digitized and analyzed with a view of mapping the predominate geologic structures, demarcate the basin geometry, estimation of the basal depth (sedimentary thicknesses) and produce an ideological magnetic potential map of the area. The residual map is noticeable by spirogyra and uneven shaped bodies characterized by different magnetic values ranging from lows, highs and medium magnetic intensities within the range of -91.50nT to 41.60nT. qualitative study of the residual anomalous map shows the presence of basement rocks intrusion around north and south-western portion of the area. Downward continuation map reveals the structures are orienting in NE-SW and NW-SE direction and these conforms with trend of structures in Northern Anambra basin and by extension lower Benue trough. Result from quantitative interpretation shows two basal depth sources, the deeply seated magnetic source which ranges from 1.76 to 4.50km and the near surface seated magnetic sources, ranging from 0.50 to 1.76km. The shallower magnetic basal depth sources are believed to be as a result of basement intrusion or magnetized ore bodies inside the sedimentary infillings. 3-D surface map reveals a depression at the middle part of the study area indicating thicker sediments which trend northwest-southeast direction while the eastern and southern parts have shallower sedimentary thicknesses. The high pass filter map depicts anomalies between the range -16.0nT and 8.7nT. Keywords: Spectral Analysis, Magnetic Potential, Basin Configuration, High-pass-filter, Downward-Continuation. DOI: 10.7176/JEES/11-4-04 Publication date: April 30 th 2021

Increasing bamboo dominance in southwestern Amazon forests following intensification of drought-mediated fires

Since the late 1980s the Amazon rainforest has been affected by major forest fires every 3–5 years, mainly in the southwestern portion of the region. Besides the reduction of forest biomass and changes in structure and floristic composition, these forest fires favor the expansion of bamboo in forests in the southwestern Amazon. However, we know little about the impact of fire on bamboo expansion and changes in forest structure. The goal of this study is to quantify forest degradation by fire in areas with bamboo in the eastern portion of the state of Acre, Brazil, based upon a combination of forest-inventory and satellite remote-sensing data. The forest fires were defined by remote sensing as those in which the crowns of the trees were directly or indirectly affected by fire to the point that they cause a detectable impact on the optical satellite images in the 1984–2016 period. We measured trees and bamboo in 6 ha distributed in twelve 0.5-ha plots (100 m × 50 m) in unburned forest, forest burned in 2005, burned forest in 2010 and forest burned in both 2005 and 2010. Our results show change in the structure of the forest with a reduction in the number of live trees as the number of bamboo culms increases after the forest fires. The amount of breakage and damage to the trees by the bamboo culms can double or triple with the expansion of the bamboo after fire impact. Bamboo expansion was identified based on an increase of the proportion of pixels with near-infrared channel reflectance values > 3500. The impact of forest fires resulted in incursion and dominance of bamboo culms over an area of 120,000 ha, changing the forest type of this area to “bamboo-dominated forest.” Our results clearly show that drought-induced forest fires with anthropogenic sources are capable of shifting the structure of forest in southwestern Amazonia towards bamboo-dominated forest. With future climate scenarios indicating more frequent and extensive droughts due to global warming, which, together with the use of fire for new deforestation and for managing pasture and agricultural fields, can be expected to cause more forests in southwestern Amazonia to be exposed to extensive fires and potential increase in bamboo density.

Foraminifera and Ostracoda from the Lower Cretaceous (Aptian–lower Albian) romualdo formation, Araripe basin, northeast Brazil: Paleoenvironmental inferences

The goal of this study is to investigate the Aptian–lower Albian microfossil association present in the Romualdo Formation, Araripe Basin, Pernambuco State, northeastern Brazil. Fifty-six samples of calcarenites and claystones were collected from the level where marine invertebrates are concentrated and in the coquinoid limestones, which compose the transgressive strata of the Romualdo Formation. The samples were from five outcrops (Cedro, Santo Antônio, Arrojado, Canastra and Torre Grande) located in the south-central region of the Araripe Basin. Nine species of foraminifera and five species of ostracods were found. The foraminifera species were: Agathammina cf. pusilla, Agathammina sp., Spiroloculina sp. 1. Spiroloculina sp. 2, Quinqueloculina sp. Astacolus sp., Gaudrynopsis sp., Conorboides minutissima and Lingulogavelinela sp. The recorded foraminifera associations are representative of different environments, from shallow marine settings to hypersaline lagoons. The five species of ostracods were: Pattersoncypris salitrensis, Pattersoncypris symetrica, Pattersoncypris sinuata, Pattersoncypris cf. micropapillosa and Damonella grandiensis. The ostracods inhabited a myxohyaline environment and tolerated the variation of salinity occurred during the deposition of the Romualdo Formation. Three assemblages were identified and their stratigraphic position was determined for each outcrop, suggesting that the south-central portion of the Araripe Basin presents clearer evidence of marine influence than the southwestern portion. Although a precise reconstruction of the route of marine ingression would require additional studies, the presence of the foraminifera genus Agathammina indicates an affinity with the Tethyan fauna. Therefore, we can conclude that the marine ingression during the Aptian–Albian followed a north-northeast direction, reaching initially the south-central part of the basin.

The 25 March 2020 MW 7.5 Paramushir, northern Kuril Islands earthquake and major (MW ≥ 7.0) near-trench intraplate compressional faulting

Large compressional-faulting earthquakes located relatively deep in oceanic lithosphere entering subduction zones are primarily caused by plate bending stress, but their timing, depth extent and size can be influenced by temporally-varying shear stress on the plate boundary. The 25 March 2020 MW 7.5 event in the Pacific plate seaward of Paramushir Island (northern Kuril Islands), is among the largest recorded events of this type. Its rupture extends along a large-slip region in the southwestern portion of the 1952 Kamchatka MW 9.0 rupture zone. This region has somewhat lower interplate coupling than the megathrust fault along Kamchatka to the northeast, but there could be 68 yrs of strain accumulation. The 2020 event is considered in the context of the 24 recorded major (MW≥7.0) near-trench intraplate compressional-faulting events. An updated compilation of temporally varying near-trench intraslab faulting relative to major interplate ruptures indicates that the stress cycles on the plate boundary influence both extensional and compressional near-trench faulting caused by plate bending. Particularly noteworthy are such events seaward of areas presumed to be in an advanced stage of their seismic cycle, including relatively shallow compressional events along the 1944 MW 8.1 Tonankai, Japan rupture zone, along with activity along the 1952 Kamchatka and 1922 Chile rupture zones.

Normalizing home ranges of immature Kemp’s ridley turtles (Lepidochelys kempii) in an important estuarine foraging area to better assess their spatial distribution

ABSTRACT Kemp’s ridley turtles (Lepidochelys kempii) are critically endangered sea turtles that forage seasonally in Chesapeake Bay, a large estuary on the east coast of the United States. Most of the Kemp’s ridley turtles foraging in the bay are immature. When tracking these animals, satellite transmitter retention times have been low compared with adult marine turtles of other species. The immature Kemp’s ridleys’ small size and rapid growth leads to shorter, more variable deployments, limiting the use of data. These limited data leave critical questions remaining about the animals’ habitat usage that are difficult to answer without substantially more deployments. A novel sensitivity analysis using simulated deployments indicated that too few animals were tagged with satellite transmitters to identify all possible home-range areas in the Bay. We used simulation to create animal deployments of equal duration to address biases (differing lengths of deployments and time between locations) in home-range analyses and boost the information available from relatively short deployments. Combined home ranges from simulated deployments identified important areas for these animals in the south-western portions of the Chesapeake Bay and in the nearshore areas of the Bay north to the middle of the Bay. These areas represent opportunities for managers to mitigate impacts from boating, dredging, military activities and fishing, and could inform critical habitat designations under the United States Endangered Species Act. Habitat modelling may be needed to identify additional important areas in the Bay where animals were not observed via satellite tracking.

Remote Sensing of Wetland Area Loss and Gain in the Western Barataria Basin (Louisiana, U.S.A.) since Hurricane Katrina

Potter, L., 2021. Remote sensing of wetland area loss and gain in the western Barataria Basin (Louisiana, U.S.A.) since Hurricane Katrina. Journal of Coastal Research, 37(5), 953–963. Coconut Creek (Florida), ISSN 0749-0208. The goal of this study was to analyze the recent record of Landsat satellite imagery to better understand spatial patterns and infer processes of change in marshland vegetation cover in coastal Louisiana wetlands. The study area covered subbasins of the western Barataria Basin near the Bayou Lafourche in southeastern Louisiana. Bayou Lafourche's estuaries have seen some of the highest rates of wetland conversion to open water of any coastal zone in the United States. The Landsat Normalized Difference Water Index (NDWI) was used in this study to map changes in land/water fractions at a 30-m pixel resolution between October 2005 (post-Katrina) and October 2018. Validation boat surveys were conducted in July 2020 to visually verify the presence or absence of (>1 m) emergent vegetation growing on marshlands across several subbasins, with photographs collected at more than 150 target locations along the route. Based on NDWI change, a total of 42.3 km2 was estimated to fall into the category of wetland loss since 2005. The leading subbasins for these recent wetland-to-water conversions made up most of the southwestern portion of the study area just north of Port Fourchon. The consistently low distance detected between the majority of wetland loss cells and locations of historical oil and gas wells implies that effects of well drilling and extraction have had a continuing negative impact on marshland degradation in the basin. Conversely, a total of 34 km2 was estimated to fall into the category of recent wetland gain, with much of the new vegetation growth verified to have been restored within several shoreline protection and dredging projects. It was concluded that the positive contributions made by such shoreline enhancement and marshland nourishment projects in Lafourche Parish to offset wetland losses over the past 15 years should not be underestimated.

Textural Implications in Assessment of Physico-Mechanical behaviour of Metavolcanic Rocks from Dir Upper, north western Pakistan

The Dir-Utror meta-volcanics from the south western portion of the Kohistan arc in northern Pakistan areanalyzed in term of their petrography, physico-mechanical properties. Field observations and petrography show thecollected representative samples to be fine-grained meta-andesites (FMA), coarse-grained meta-andesites (CMA) andagglomerate (AG). The relationship between petrography and physico-mechanical properties has been investigatedwhich inferred the grain size to be the major factor, alongside grains’ shape, arrangement and size distribution as wellas degree of mineral alteration significantly affecting the mechanical behavior of rocks. The CMA yield more strength(98 MPa) than FMA (93 MPa) due to its lesser degree of mineral alteration, inequigranular texture, lack of preferredmineral alignment, relatively low porosity and water absorption. The lower strength of agglomerate (57 MPa)corresponds to abundance of soft minerals (calcite), exotic rock fragments and coarse-grained texture. Based onphysico-mechanical properties including specific gravity, bulk density, aggregate impact value, Los Angeles abrasionvalue and unconfined compressive strength (UCS), these rocks fall within permissible range to be utilized for multipleengineering purposes including dimension stones and foundation materials for other civil structures. However,petrographic investigations reveal excessive amount of reactive silica in these rocks making them prone to alkali-silicareactivity in concrete works with ordinary Portland cement (OPC). Hence these rocks are not recommended for use assole aggregate material or low-alkali cement is recommended, if used.

Studying the Regional Transmission and Inferring the Local/External Contribution of Fine Particulate Matter Based on Multi-Source Observation: A Case Study in the East of North China Plain

The regional transmission characteristics as well as the local emission and external transmission contribution of fine particulate matter in the eastern North China Plain were investigated using multisource data. Himawari-8 aerosol optical depth can represent the whole layer of air pollution situation; hourly aerosol optical depth were used to reconstruct the route of fine particulate matter horizontal transmission, and the transmission speed was calculated and compared with the near-surface wind speed. A case study conducted on 22 September 2019 showed the pollutant was mainly transmitted from Tangshan to Dezhou, and the transmission speed was greater than the near-surface wind speed. We also found that pollution air mass had 2–3 h of diffusion delay in the near-surface pollutant monitoring results. In addition, the vertical diffusion of pollution mainly occurred at low altitude below 1.8 km. The contribution of local emission and external transmission was inferred in this study with the help of the WRF-Chem model, the pollution in the northeastern portion of the study area mainly derived from local emissions, while the southwestern portion of the study area was mainly affected by external transport. Among them, the local emission accounted for 79.15% of the pollution in Tangshan, while the external transmission contributed 60.28% of the fine particulate matter concentration in Dezhou.

A new nurse frog (Anura: Allobates) from Brazilian Amazonia with a remarkably fast multi-noted advertisement call.

Nurse frogs (Aromobatidae: Allobates) are probably the most extensively studied genus by taxonomists in Brazilian Amazonia. The southwestern portion of Amazonia is the most species-rich: as many as seven species may occur in sympatry at a single locality. In this study, we describe a new species of nurse frog from this region. The description integrates data from larval and adult morphology, advertisement calls and DNA sequences. Allobates velocicantus sp. nov. is distinguished from other Allobates mainly by the absence of hourglass-shaped dark marks on the dorsum and dark transverse bars on the thigh; a throat that is white centrally and yellow marginally; basal webbing on toes II and III; finger I longer than finger II; and an advertisement call composed of 66–138 pulsed notes with a note duration of 5–13 ms, inter-note intervals of 10–18 ms and a dominant frequency of 5,512–6,158 Hz. Tadpoles of the new species have 3–4 short, rounded papillae on the anterior labium, 16–23 papillae on the posterior labium, and a labial keratodont row formula 2(2)/3(1). This is the fifth species of Allobates described from the state of Acre, southwestern Brazilian Amazonia.

Rediscovery of Chiococca insularis (Ridley) C.M.Taylor & M.R.V. Barbosa (Rubiaceae), a species presumed extinct, on the island of Fernando de Noronha, Pernambuco, Brazil

Chiococca insularis (Ridley) C.M.Taylor & M.R.V.Barbosa (Rubiaceae) was described by Henry Nicholas Ridley in 1890, based on a collection he made on the island of Fernando de Noronha (Pernambuco, Brazil) in 1887. Since then, this species had not been collected again and has been treated as probably extinct. After 130 years, we discovered two new populations in the southwestern portion of the island, and the conservation status of the species is reassessed. A full description of the species, with previously unseen or unmeasured characters, habitat information and photographs of the plant and environment are provided.

A influência da variação zonal da confluência Brasil-Malvinas na safra da tainha no estado de Santa Catarina entre os anos 2006 a 2016

The Brazil-Malvinas Confluence (CBM) comprises the region located in the southwestern portion of the Atlantic Ocean, with a strong influence on meteorological aspects and oceanographic phenomena, including sea surface temperature (SST). Variations in SST, influence the dynamics and behavior of aquatic species and consequently the fishing productivity of mullet (Mugil liza), a species of great economic importance in the state of Santa Catarina. The present study deals with the analysis of the influence of the CBM zonal variation on the sea surface temperature (SST) in southern Brazil, making a comparison with the data of the fish harvest in the Santa Catarina coast, considering a period of 11 years (2006 to 2016) and in the months of fishing (April to July). From the data analysis it is possible to identify the characteristic behavior of the period and to analyze the influencing factors.

New records of Apostolepis kikoi Santos et al., 2018 (Serpentes, Dipsadidae) in the state of Mato Grosso, Central-West Brazil

The fossorial snake Apostolepis kikoi Santos et al., 2018 is known only from its type locality, in Chapada dos Guimarães, state of Mato Grosso, Brazil. Here, we present the first records of this species after its description, expanding its distribution to transition areas between the Amazon and Cerrado biomes, in the southwestern portion of Mato Grosso. The new record expands the known distribution of A. kikoi by 297 km west from the type locality. In addition, we provide data on morphological variation by comparing our sample with the type series.

Detecção e delimitação de pequenos reservatórios na Bacia Hidrográfica do Rio Cachoeira, Bahia, utilizando imagens multiespectrais

No presente trabalho foram utilizadas imagens multiespectrais do satélite Sentinel-2 da Bacia Hidrográfica do Rio Cachoeira (BHRC), localizada no sul do estado da Bahia. O objetivo deste trabalho foi detectar, delimitar e quantificar a área ocupada por reservatórios de água na BHRC. Para tanto foram calculados os índices MNDWI (Modified Normalized Difference Water Index) e NDWI (Normalized Difference Water Index). A capacidade de detecção de pequenos corpos d’água pelos métodos empregados mostrou-se satisfatória, apresentando uma correspondência de até 78% entre os métodos, com superiores resultados para índice MNDWI frente ao NDWI. A partir desses índices foram observadas variações sazonais e espaciais quanto à distribuição de reservatórios na BHRC. A porção sudoeste da bacia apresentou maior concentração de pequenos reservatórios no período chuvoso. No contexto geral da bacia hidrográfica, os reservatórios de água ocupam até 0,13% da área da bacia, enquanto que em determinadas áreas do sudoeste da BHRC esse valor atinge até 0,86%.

Extreme waves generated by cyclonic winds in the western portion of the South Atlantic Ocean

This article analyzes the spatial distribution of extreme waves generated by extratropical cyclones and studies the atmospheric conditions that lead to the most severe events in the Southwestern portion of the South Atlantic Ocean. Significant wave heights from the NCEP/WW3 hindcast and atmospheric fields from NCEP/CFSR are selected for the analysis that joins automatic tracking of the storms with visual analyses of the most relevant cases. The synoptic pattern of extreme events suggested that extreme waves can occur in three regions of the cyclones: (1) behind the cold front; (2) along the warm front; and (3) ahead of the cold front. The first pattern is widely reported in the literature, while the others are unexplored in the region and are first reported in this paper. It was also shown that the anticyclone position relative to the cyclone center plays an important role in the extreme waves in two ways: (1) due to the increase of horizontal pressure gradient and, consequently, surface wind speed; and (2) affecting the cyclone displacement speed, which determines the fetch positioning and the wave generation process. The novel features identified show that slow cyclones tend to promote longer events of extreme waves, with impact on larger areas.

Remnant American Chestnut (Castanea dentata) Near the Historical Western Range Limit in Southwestern Tennessee

The American chestnut (Castanea dentata) was once widespread in eastern North America and an ecologically important hardwood tree of deciduous forest communities prior to its near-eradication by chestnut blight (Cryphonectria parasitica). Remnant populations occur across much of its historical range, especially in older forests of the Appalachians and northeastern U.S. However, broad swaths of the southwestern portion of the species' historical range remain poorly documented, potentially limiting the representation of genetic variation important for local adaptation in restoration efforts. Ongoing discovery and life-history characterization efforts for remnant C. dentata remains a priority to better understand the distribution and ecological status of this once important species, while identifying potential genetic sources of locally adapted or blight resistant trees. Here, we report the discovery of 22 C. dentata at four sites in southwestern Tennessee, adding novel observations that extend the range of known extant occurrences to the extreme western edge of the historical distribution in Fayette County. These observations include potentially reproductive individuals that should be revisited to assess reproductive and blight status, and that should be evaluated for current germplasm collection and restoration efforts.

Environmental isotopes and hydrochemical tracers applied to hydrogeological conceptual modeling of the southwest portion of the Amazon Aquifer System (Acre, Brazil)

Geochemical and environmental isotope techniques are successfully applied to understand the origin and evolution of groundwater in aquifers, with the aim of producing consistent conceptual models. In the present study, δ18O, δ2H, and δ13C stable isotope ratios and 14C and 3H levels were used for this purpose. One of the most important aquifer systems in South America, the Amazon Aquifer System (AAS), remains almost entirely unstudied in this aspect. The combination of hydrochemical and isotopic tracers was applied in a pioneer study to foster the understanding of the driving hydrogeological processes in the southwestern portion of the AAS, in the Acre Sedimentary Basin (ASB), northwestern Brazil. The study area comprises three aquifers: from top to bottom of the system, the Quaternary Aquifer, the Içá–Solimões Aquifer (Paleogene/Neogene), and the Tikuna Aquifer (Cretaceous). The aquifers have distinct hydrochemical characteristics, acidic pH and Na–HCO3 waters in the Quaternary Aquifer, pH ~8 and Ca–HCO3 and Na–HCO3 waters in the Içá–Solimões Aquifer, and neutral pH and Ca–HCO3 waters in the lower Tikuna Aquifer system. Ion exchange processes predominate in all three aquifers, but carbonate dissolution also occurs in some parts of the Içá–Solimões Aquifer. The Içá–Solimões Aquifer shows a geochemical evolution along the regional flow from southwest to northeast. δ18O and δ2H measurements of the groundwater align with the global meteoric water line, without a significant evaporative effect or dispersion. Groundwater from the Içá–Solimões and Tikuna Aquifers is more depleted than the weighted rainfall average (δ2H = −27.9‰ and δ18O = −5.35‰, respectively). The deuterium excess of the local rainfall is approximately +14‰. Residence times, estimated by 14C, range between 13 and 18 ka in the Içá–Solimões Aquifer and reach approximately 6 ka in the Tikuna Aquifer. In addition, tritium concentrations lower than 0.6 TU pointed to the absence of recent waters in the studied aquifers. Local structural and stratigraphic features in the Serra do Divisor area, where asymmetric folding and faulting occur, affect the functioning and features of these aquifer systems, originating from the erosive exposure of deeper and older layers to recent recharge. Thus, geologically older and subjacent aquifer units (Tikuna Aquifer) hold more recently circulating waters than the younger and shallower ones (Içá–Solimões Aquifer).

Cropping system yield gaps can be narrowed with more optimal rotations in dryland subtropical Australia

Closing the gap between yields currently achieved on farms and those that can potentially be achieved with best practice and current technology (the yield gap) is a key strategy to intensify grain production without expanding cropland. Much research has been done to quantify the yield gap of wheat, maize and rice globally and of wheat, barley, canola, sorghum and pulse crops in Australia. However, crops are grown in rotations (recurring crop sequences) that vary in their cropping intensities and in the diversity of their species. Little is known about yield gaps at the cropping system level, especially in regions where there are many possible combinations of crop types and fallow periods. This prompted us to investigate crop rotations in Australia's subtropical grains region where current crop rotations include winter and summer cropping with cereal, pulse and oilseed crops interspersed with fallow periods ranging from nil to 18 months duration. To determine the system level yield gaps, we simulated the water-limited yield potential of 26 locally practiced crop rotations for over 800 weather stations by up to 3 soil types per station. We captured the impact of climate variability with 30–35 years by 2–7 fields per rotation for each site. We expressed the results in terms of energy, protein and revenue per hectare per year and mapped the results of the optimal rotations over the cropping zone. Surprisingly, a single rotation (sorghum/fallow/mungbean/wheat/fallow/chickpea rotation; with 4 crops in 3 years, balanced between summer and winter crops and between cereal and pulse crops) was optimal for revenue over almost the whole subtropical grain zone. Using revenue as the metric for yield gaps at statistical local area scale we found, over the whole subtropical zone, a mean revenue gap of 970 $/ha/yr. This represents a relative revenue (Revenue% = 100 x (actual revenue/water-limited revenue)) of 34% which is much lower than expected from the 40–60% relative yields achieved by individual crops. We investigated whether growers may select rotations that have lower revenue than the optimal rotation in response to economic factors such as profit and risk. We found that for much of the area the same rotation that optimised revenue also optimised profit. However, for some of the cropping zone, particularly in the south western portion, a different, less intensive and more winter dominant, rotation was most profitable. Similarly, risk averse farmers may choose less productive and profitable rotations with less risk.

New acoustic and molecular data shed light on the poorly known Amazonian frog Adenomera simonstuarti (Leptodactylidae): implications for distribution and conservation

Adenomera simonstuarti is a poorly known species complex inhabiting western Amazonia. Here we reevaluate the species diversity within this complex based on previously documented and newly acquired molecular and phenotypic data. We also redescribe the calling pattern of the nominal species based on the original recording (Peru) and a new recording (Brazil). Our results indicate eight geographically structured genetic lineages and the nominal species with a multi-note call pattern. This is the first association of calls and DNA sequence from a voucher specimen, thereby enabling the assignment of A. simonstuarti to one specific lineage within the complex. The multi-note call was not previously reported and represents an important additional diagnostic character within Adenomera. The geographic distribution of A. simonstuarti is substantially narrowed down to the southwestern portion of the entire geographic range recognized for the complex. The lack of taxonomic resolution in the complex is a major conservation concern by preventing us from evaluating the potential threats and extinction risks of each of the lineages. Future research should follow the protocol of combining calls and DNA sequences associated with voucher specimens as a means to address the taxonomic status of genetic lineages within the A. simonstuarti complex.