Importance of methodological pluralism in deriving counterfactuals for evidence-based conservation.

Most protected area impact research that uses counterfactuals draws heavily on quantitative methods, data, and knowledge types, making it valuable in producing generalizations but limited in temporal scope, historical detail, and habitat diversity and coverage of ecosystem services. We devised a methodological pluralistic approach, which supports social science qualitative methods, narratives, mixed methods, and interdisciplinarity, to fully unlock the potential of counterfactuals in ensuring a place-based and detailed understanding of the socioecological context and impacts of protected areas. We applied this approach to derive possible counterfactual conditions for the impact of a montane protected area on 40 years of vegetation change in the Cape Floristic Region-a global biodiversity hotspot and UNESCO World Heritage Site in South Africa. We incorporated diverse methods, knowledge, and information sources, drawing on before-after protected area comparisons for inside and outside the protected area. A significant increase in shrubland vegetation (17-30%) was observed and attributed primarily to a decline in frequent burning for grazing. This also occurred outside the protected area and was driven by socioeconomic drivers and not by concerns over biodiversity conservation or land degradation. Had the protected area not been established the area would have seen intensification of cultivation and increased road networks, buildings, and water storage in dams. Our approach increased historical temporal coverage of socioecological change and contextualized assumptions around causality. Protected area impact evaluation should reengage in place-based research that fully incorporates pluralism in methodologies for constructing counterfactuals in a way that builds regional and global understanding from the local level upward. We devised 10 key principles for deriving counterfactuals grounded in methodological pluralism, covering aspects of collaboration, cocreation, inter- and transdisciplinarity, diverse values and lived experiences, multiple knowledge types, multiple possible causal mechanisms, social science qualitative methods, perceptions, perspectives, and narratives.

Importancia del pluralismo metodológico en la derivación de situaciones contrafactuales para la conservación basada en evidencias Resumen La mayoría de las investigaciones sobre el impacto de las áreas protegidas que usan situaciones contrafactuales se basan en gran medida en métodos cuantitativos, datos y tipos de conocimiento, por lo que son muy valiosas para producir generalizaciones, pero limitadas en el enfoque temporal, el detalle histórico y la diversidad de hábitats y cobertura de los servicios ambientales. Diseñamos una estrategia metodológica pluralista, la cual apoya los métodos cualitativos de las ciencias sociales, narrativas, métodos mixtos e interdisciplinarios para utilizar por completo el potencial de las situaciones contrafactuales para asegurar un conocimiento detallado y basado en el lugar del contexto socio ecológico y el impacto de las áreas protegidas. Aplicamos esta estrategia para derivar las posibles condiciones contrafactuales del impacto de un área protegida montañosa sobre 40 años de cambio de vegetación en el reino florístico del Cabo ­ un punto caliente de biodiversidad y Sitio de Patrimonio Mundial de la UNESCO en Sudáfrica. Incorporamos varios métodos, conocimientos y fuentes de información a partir de las comparaciones antes­después dentro y fuera del área protegida. Observamos un incremento significativo en la vegetación del matorral (17­30%), el cual atribuimos principalmente en la disminución de la quema frecuente para el pastoreo. Esto también ocurrió fuera del área protegida y fue causado por factores socioeconómicos y no por preocupación por la conservación de la biodiversidad o por la degradación del suelo. De no haberse establecido el área protegida, la zona habría sufrido una intensificación de cultivos y un incremento de carreteras, edificios y almacenamiento de agua en presas. Nuestra estrategia incrementó la cobertura histórica temporal del cambio socio­ecológico y contextualizó las suposiciones sobre la causalidad. La evaluación del impacto del área protegida debe volver a la investigación basada en el lugar que incorpora de lleno el pluralismo en la metodología para construir situaciones contrafactuales de una forma que genere conocimiento regional y global a partir del nivel local y hacia arriba. Diseñamos diez principios clave para derivar las situaciones contrafactuales basados en el pluralismo metodológico, la cobertura de los aspectos de colaboración, creación conjunta, inter­ y transdisciplinariedad, valores diversos y experiencias vividas, varios tipos de conocimiento, diferentes mecanismos causales posibles, métodos cualitativos de las ciencias sociales, percepciones, perspectivas, historias y narrativas.

A new framework for evaluating dust emission model development using dichotomous satellite observations of dust emission.

Dust models are essential for understanding the impact of mineral dust on Earth's systems, human health, and global economies, but dust emission modelling has large uncertainties. Satellite observations of dust emission point sources (DPS) provide a valuable dichotomous inventory of regional dust emissions. We develop a framework for evaluating dust emission model performance using existing DPS data before routine calibration of dust models. To illustrate this framework's utility and arising insights, we evaluated the albedo-based dust emission model (AEM) with its areal (MODIS 500 m) estimates of soil surface wind friction velocity (us∗) and common, poorly constrained grain-scale entrainment threshold (u∗ts) adjusted by a function of soil moisture (H). The AEM simulations are reduced to its frequency of occurrence, P(us∗>u∗tsH). The spatio-temporal variability in observed dust emission frequency is described by the collation of nine existing DPS datasets. Observed dust emission occurs rarely, even in North Africa and the Middle East, where DPS frequency averages 1.8 %, (~7 days y-1), indicating extreme, large wind speed events. The AEM coincided with observed dust emission ~71.4 %, but simulated dust emission ~27.4 % when no dust emission was observed, while dust emission occurrence was over-estimated by up to 2 orders of magnitude. For estimates to match observations, results showed that grain-scale u∗ts needed restricted sediment supply and compatibility with areal us∗. Failure to predict dust emission during observed events, was due to us∗ being too small because reanalysis winds (ERA5-Land) were averaged across 11 km pixels, and inconsistent with us∗ across 0.5 km pixels representing local maxima. Assumed infinite sediment supply caused the AEM to simulate dust emission whenever P(us∗>u∗tsH), producing false positives when wind speeds were large. The dust emission model scales of existing parameterisations need harmonising and a new parameterisation for u∗ts is required to restrict sediment supply over space and time.

'Follow the Water': Microbial Water Acquisition in Desert Soils.

Water availability is the dominant driver of microbial community structure and function in desert soils. However, these habitats typically only receive very infrequent large-scale water inputs (e.g., from precipitation and/or run-off). In light of recent studies, the paradigm that desert soil microorganisms are largely dormant under xeric conditions is questionable. Gene expression profiling of microbial communities in desert soils suggests that many microbial taxa retain some metabolic functionality, even under severely xeric conditions. It, therefore, follows that other, less obvious sources of water may sustain the microbial cellular and community functionality in desert soil niches. Such sources include a range of precipitation and condensation processes, including rainfall, snow, dew, fog, and nocturnal distillation, all of which may vary quantitatively depending on the location and geomorphological characteristics of the desert ecosystem. Other more obscure sources of bioavailable water may include groundwater-derived water vapour, hydrated minerals, and metabolic hydro-genesis. Here, we explore the possible sources of bioavailable water in the context of microbial survival and function in xeric desert soils. With global climate change projected to have profound effects on both hot and cold deserts, we also explore the potential impacts of climate-induced changes in water availability on soil microbiomes in these extreme environments.

Satellites reveal Earth's seasonally shifting dust emission sources.

Establishing mineral dust impacts on Earth's systems requires numerical models of the dust cycle. Differences between dust optical depth (DOD) measurements and modelling the cycle of dust emission, atmospheric transport, and deposition of dust indicate large model uncertainty due partially to unrealistic model assumptions about dust emission frequency. Calibrating dust cycle models to DOD measurements typically in North Africa, are routinely used to reduce dust model magnitude. This calibration forces modelled dust emissions to match atmospheric DOD but may hide the correct magnitude and frequency of dust emission events at source, compensating biases in other modelled processes of the dust cycle. Therefore, it is essential to improve physically based dust emission modules. Here we use a global collation of satellite observations from previous studies of dust emission point source (DPS) dichotomous frequency data. We show that these DPS data have little-to-no relation with MODIS DOD frequency. We calibrate the albedo-based dust emission model using the frequency distribution of those DPS data. The global dust emission uncertainty constrained by DPS data (±3.8 kg m-2 y-1) provides a benchmark for dust emission model development. Our calibrated model results reveal much less global dust emission (29.1 ± 14.9 Tg y-1) than previous estimates, and show seasonally shifting dust emission predominance within and between hemispheres, as opposed to a persistent North African dust emission primacy widely interpreted from DOD measurements. Earth's largest dust emissions, proceed seasonally from East Asian deserts in boreal spring, to Middle Eastern and North African deserts in boreal summer and then Australian shrublands in boreal autumn-winter. This new analysis of dust emissions, from global sources of varying geochemical properties, have far-reaching implications for current and future dust-climate effects. For more reliable coupled representation of dust-climate projections, our findings suggest the need to re-evaluate dust cycle modelling and benefit from the albedo-based parameterisation.

Eolian chronology reveals causal links between tectonics, climate, and erg generation.

Evaluating the impact and implications of eolian repositories that mark large-scale climatic transitions requires knowledge about the timing of their emplacement and the mechanisms responsible for their production, which remain highly uncertain. Here we apply numerical modeling of cosmogenic nuclide data, measured in the largest continuous terrestrial body of sand on Earth, to determine settings under which the sand was generated, by constraining the timing of sand introduction into the interior of southern Africa. Our findings reveal that major events of sand formation and accumulation in the Kalahari Basin occurred between ~2.2 and 1 Myr ago. The establishment of the Kalahari sand field corresponds to regional, continental, and global scale morphotectonic and climatic changes that contributed to the mass production and widespread dispersion of sand. These changes substantially altered existing habitats, thus constituting a crucial milestone for flora, fauna, and hominins in southern Africa during the Pleistocene.

Gone with the Wind: Microbial Communities Associated with Dust from Emissive Farmlands.

Dust is a major vehicle for the dispersal of microorganisms across the globe. While much attention has been focused on microbial dispersal in dust plumes from major natural dust sources, very little is known about the fractionation processes that select for the "dust microbiome." The recent identification of highly emissive, agricultural land dust sources in South Africa has provided the opportunity to study the displacement of microbial communities through dust generation and transport. In this study, we aimed to document the microbial communities that are carried in the dust from one of South Africa's most emissive locations, and to investigate the selective factors that control the partitioning of microbial communities from soil to dust. For this purpose, dust samples were generated at different emission sources using a Portable In-Situ Wind Erosion Lab (PI-SWERL), and the taxonomic composition of the resulting microbiomes was compared with the source soils. Dust emission processes resulted in the clear fractionation of the soil bacterial community, where dust samples were significantly enriched in spore-forming taxa. Conversely, little fractionation was observed in the soil fungal communities, such that the dust fungal fingerprint could be used to identify the source soil. Dust microbiomes were also found to vary according to the emission source, suggesting that land use significantly affected the structure and fractionation of microbial communities transported in dust plumes. In addition, several potential biological allergens of fungal origin were detected in the dust microbiomes, highlighting the potential detrimental effects of dust plumes emitted in South Africa. This study represents the first description of the fractionation of microbial taxa occurring at the source of dust plumes and provides a direct link between land use and its impact on the dust microbiome.

Natural chlorate in the environment: application of a new IC-ESI/MS/MS method with a Cl¹8O3-internal standard.

A new ion chromatography electrospray tandem mass spectrometry (IC-ESI/MS/MS) method has been developed for quantification and confirmation of chlorate (ClO3⁻) in environmental samples. The method involves the electrochemical generation of isotopically labeled chlorate internal standard (Cl¹8O3⁻) using ¹8O water (H2¹8O) he standard was added to all samples prior to analysis thereby minimizing the matrix effects that are associated with common ions without the need for expensive sample pretreatments. The method detection limit (MDL) for ClO3⁻ was 2 ng L⁻¹ for a 1 mL volume sample injection. The proposed method was successfully applied to analyze ClO3⁻ in difficult environmental samples including soil and plant leachates. The IC-ESI/MS/MS method described here was also compared to established EPA method 317.0 for ClO3⁻ analysis. Samples collected from a variety of environments previously shown to contain natural perchlorate (ClO4⁻) occurrence were analyzed using the proposed method and ClO3⁻ was found to co-occur with ClO4⁻ at concentrations ranging from < 2 ng L⁻¹ in precipitation from Texas and Puerto Rico to >500 mg kg⁻¹ in caliche salt deposits from the Atacama Desert in Chile. Relatively low concentrations of ClO3⁻ in some natural groundwater samples (0.1 µg L⁻¹) analyzed in this work may indicate lower stability when compared to ClO4⁻ in the subsurface. The high concentrations ClO3⁻ in caliches and soils (3-6 orders of magnitude greater) as compared to precipitation samples indicate that ClO3⁻, like ClO4⁻, may be atmospherically produced and deposited, then concentrated in dry soils, and is possibly a minor component in the biogeochemical cycle of chlorine.