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Zero plane displacement height ( d 0 ) and momentum roughness length ( z 0 m ), describe the aerodynamic characteristics of a vegetated surface. Usually, d 0 and z 0 m are assumed to be constant functions of the physical characteristics of the surface. Prior evidence collected from the literature and our examination of flux tower data show that d 0 and z 0 m vary in time at sites with tree and shrub canopies, but not grasslands. The conventional explanations of these variations are based on linear functions of wind velocity and friction velocity, with little theoretical basis. This study explains the variation in aerodynamic parameters by matching four analytical canopy velocity models to a logarithmic above-canopy velocity profile at canopy height. d 0 and z 0 m come out as functions of 2 non-dimensional terms, the canopy momentum absorption capacity (parameter) and a (measurable) Péclet number. To test the theories of variation, we analysed the velocity profiles from Ozflux and Ameriflux sites. None of the theories could recreate d 0 and z 0 m at half-hourly intervals. However, the canopy velocity models were able better to recreate the distribution of the variations in d 0 and z 0 m . Additionally, the estimates of canopy momentum absorption capacity varied consistently with phenological changes in the canopies, whereas, the fitting parameters of the linear regression of using wind speed and friction velocity did not exhibit physically interpretable variations. The canopy velocity models may offer better predictions with an accurate estimation of the canopy height, a horizontally homogeneous and rigid canopy, and incorporation of the roughness sublayer. [ABSTRACT FROM AUTHOR]

Under global warming, drought will reduce productivity of Pinus halepensis s.l. (subspecies halepensis and brutia) and cause a retreat from its rear edge distribution (latitudinal/elevational) in the Mediterranean. To test whether topography can influence this scenario, we studied for approximately 40 years the growth of six natural pine stands in water-limited habitats on the islands of Zakinthos and Samos (eastern Mediterranean Greece), and determined the critical moisture sources that drove pine growth. Dominant pines were selected with no permanent water sources under contrasting moisture conditions created by topography ("wet"-gulley/valley vs. "dry"-upslope habitats). The responses of P. halepensis s.l. to drought under a moderate and a worst case scenario were tested, projected under global warming (approx. − 25% and 40% in annual precipitation compared to 1961–1990 average). Our results show that "wet" habitat pines had higher productivity under normal to wet climate. However, the more precipitation declined, "wet" habitat tree growth was reduced at a significantly faster rate, but also showed a faster recovery, once rainfall returned. Thus, Pinus halepensis s.l. populations in gullies/valleys, may be more drought resilient and less likely to retreat towards higher elevation/latitudes under global warming, compared to pines on dry upslope sites. Under moderate drought, both ecosystems relied on deeper moisture pools supplied by rainfall of the previous 3–6 years (including the year of growth). However, valley/gully habitat pines on significantly deeper soils (and probably on deeper heavily weathered bedrock), appeared to utilize surface moisture from winter/spring rainfall more efficiently for survival and recovery. Thus, deep soils may provide the key "buffer" for pine survival in such ecosystems that could act as potential refugia for P. halepensis s.l. under climate change. [ABSTRACT FROM AUTHOR]

A taxonomic revision of the Pultenaea setulosa species complex (Fabaceae, tribe Mirbelieae) is presented. Prior to this study, P. setulosa Benth. was broadly circumscribed as a single, morphologically variable species. Here, we present evidence supporting the recognition of 18 species, 14 of which are new to science. Pultenaea setulosa is recircumscribed as a morphologically uniform taxon endemic to the Marlborough region in south-east Queensland. We reinstate Pultenaea boormanii H.B.Will., Pultenaea campbellii Maiden & Betche and Pultenaea lapidosa Corrick from synonymy of P. setulosa and describe an additional 14 new species: Pultenaea acanthocalyx R.L.Barrett & Clugston, Pultenaea corrickiae R.L.Barrett, Orme & Clugston, Pultenaea estelleae R.L.Barrett & Clugston, Pultenaea farmeriana R.L.Barrett, Orme & P.H.Weston, Pultenaea hoskingii R.L.Barrett & Clugston, Pultenaea imminuta R.L.Barrett & S.F.McCune, Pultenaea murrayi R.L.Barrett, Pultenaea palssoniae R.L.Barrett & Clugston, Pultenaea praetermissa R.L.Barrett & Albr., Pultenaea purdieae R.L.Barrett & Clugston, Pultenaea renneri R.L.Barrett & Clugston, Pultenaea venusta R.L.Barrett & Orme, Pultenaea westonii R.L.Barrett & Clugston and Pultenaea woolcockiorum R.L.Barrett & Clugston. Sixteen of these species are endemic to New South Wales, one to Queensland and one to Victoria. All taxa are described and illustrated, and habitats and conservation status are discussed. Two additional related species, Pultenaea procumbens A.Cunn. and P. setigera A.Cunn. ex Benth. are recircumscribed. Pultenaea setigera is reinstated here, known from the type collection made in 1822 and is possibly extinct. Lectotypes are selected for the names Pultenaea boormanii, P. campbellii, P. procumbens, P. setigera and P. setulosa. [ABSTRACT FROM AUTHOR]

The global cannabis (Cannabis sativa) market was 17.7 billion in 2019 and is expected to reach up to 40.6 billion by 2024. Canada is the 2nd nation to legalize cannabis with a massive sale of $246.9 million in the year 2021. Waste cannabis biomass is managed using disposal strategies (i.e., incineration, aerobic/anaerobic digestion, composting, and shredding) that are not good enough for long-term environmental sustainability. On the other hand, greenhouse gas emissions and the rising demand for petroleum-based fuels pose a severe threat to the environment and the circular economy. Cannabis biomass can be used as a feedstock to produce various biofuels and biochemicals. Various research groups have reported production of ethanol 9.2–20.2 g/L, hydrogen 13.5 mmol/L, lipids 53.3%, biogas 12%, and biochar 34.6% from cannabis biomass. This review summarizes its legal and market status (production and consumption), the recent advancements in the lignocellulosic biomass (LCB) pre-treatment (deep eutectic solvents (DES), and ionic liquids (ILs) known as "green solvents") followed by enzymatic hydrolysis using glycosyl hydrolases (GHs) for the efficient conversion efficiency of pre-treated biomass. Recent advances in the bioconversion of hemp into oleochemicals, their challenges, and future perspectives are outlined. A comprehensive insight is provided on the trends and developments of metabolic engineering strategies to improve product yield. The thermochemical processing of disposed-off hemp lignin into bio-oil, bio-char, synthesis gas, and phenol is also discussed. Despite some progress, barricades still need to be met to commercialize advanced biofuels and compete with traditional fuels. [ABSTRACT FROM AUTHOR]

Key message: Bedrock can store appreciable amounts of available water, and some trees apparently use this resource to survive drought. Several forest ecosystems rely on only shallow soil layers overlying more or less compact bedrock. In such habitats, the largest water reservoir can be represented by rock moisture, rather than by soil water. Here, we review evidence for the presence of water available for root water uptake in some rock types, and show examples of the physiological and ecological roles of rock moisture, especially when trees are facing drought conditions. The possible magnitude of rock–root water exchanges is discussed in the frame of current knowledge of rock, soil, and root hydraulic properties. We highlight several areas of uncertainty regarding the role of rock moisture in preventing tree hydraulic failure under drought, the exact pathway(s) available for rock–root water exchange, and the relative efficiencies of water transport in the different compartments of the rock–soil–root continuum. Overall, available experimental evidence suggests that bedrock water should be incorporated into any model describing the forest seasonal water use and tree responses to drought. [ABSTRACT FROM AUTHOR]

This study applies novel risk measures, called Orlicz risks, to the risk and uncertainty evaluation of the streamflow discharge as a primary driver of hydrological and hydraulic processes of interest in civil and environmental engineering. We consider the mixed moving average process governing the discharge whose statistics are explicitly represented as some product of a time-scale characterizing the flow attenuation and a jump moment governing the size and frequency of jumps. The classical Orlicz risks are extended so that not only the upper tail risk but also the lower one of the jump size and attenuation of the discharge can be evaluated within a single mathematical framework. Further, the risk and uncertainty can be individually quantified in a tractable manner by the proposed Orlicz risks. Computing the Orlicz risks reduces to solving a pair of novel static optimization problems that are solvable semi-analytically. The risk and uncertainty involved in the streamflow dynamics can be consistently evaluated by specifying few user-dependent parameters. The associated Radon–Nikodym derivatives as the worst-case model uncertainties are obtained as byproducts. Sufficient conditions for the well-posedness of the Orlicz risks are discussed and numerical algorithms for computing them are presented. We finally apply the proposed framework to a statistical analysis of the streamflow discharge time series data collected at mountainous river environments. [ABSTRACT FROM AUTHOR]

Understanding the near-surface structure of the Earth requires accurate prediction of physical properties of the subsurface, such as velocity estimated from tomographic inversion of seismic refraction data. The predicted velocity values are often uncertain due to epistemic uncertainty in the inversion process (i.e., imperfectly known underlying physics) and aleatoric variability in the data (i.e., inherent noise in observations). Although seismic refraction is widely used in near-surface applications, the associated uncertainty is rarely quantified and presented alongside the inverted velocity tomograms. In this study, the effect of epistemic uncertainty due to local variability in the initial model and aleatoric variability due to first-arrival picking error on the velocity prediction uncertainty are investigated. A stochastic framework is implemented based on a statistical approach where multiple realizations of stochastically perturbed initial models and travel time picks are generated and the uncertainty in the predicted velocity models is quantified. The two sources of uncertainty are first studied independently and then the combined effect is investigated. The results show that both sources affect the posterior uncertainty, but the uncertainty in the initial model has a greater effect than picking error on the uncertainty of the posterior velocity model. In addition, joint analysis of both sources of uncertainty shows that the uncertainty in the inverted model depends on predicted velocity values, depths, velocity gradients and ray coverages. [ABSTRACT FROM AUTHOR]

Trees are arguably the most diverse and complex macro-organisms on Earth. The equally diverse functions of trees directly impact fluxes of carbon, water and energy from the land surface. A number of recent studies have shed light on the substantial within-species variability across plant traits, including aspects of leaf morphology and plant allocation of photosynthates to leaf biomass. Yet, within-tree variability in leaf traits due to microclimatic variations, leaf hydraulic coordination across traits at different physiological scales and variations in leaf traits over a growing season remain poorly studied. This knowledge gap is stymieing the fundamental understanding of what drives trait variation and covariation from tissues to trees to landscapes. Here, we present an extensive dataset measuring within-tree heterogeneity in leaf traits in California's blue oak (Quercus douglasii) across an edaphic gradient and over the course of a growing season at an oak–grass savanna in Southern CA, USA. We found a high level of within-tree crown leaf area:sapwood area variation that was not attributable to sample height or aspect. We also found a higher level of trait integration at the tree level, rather than branch level, suggesting that trees optimize water use at the organismal level. Despite the large variance in traits within a tree crown and across trees, we did not find strong evidence for adaptive plasticity or acclimation in leaf morphological traits (e.g. changes to phenotype which increased fitness) across temporal and spatial water availability gradients. Collectively, our results highlight strong variation in drought-related physiology, but limited evidence for adaptive trait plasticity over shorter time scales. [ABSTRACT FROM AUTHOR]

Rapid climate change and invasive species introductions threaten ecological communities across the globe. Freshwaters are particularly vulnerable and impacted, especially when these stresses coincide. We document the migration of an invasive piscine predator, the Sacramento pikeminnow (Ptychocheilus grandis), within its introduced range, the South Fork Eel River, California, USA. Snorkel surveys and temperature monitoring in 2015–2019 showed that pikeminnow migrate upstream during spring and early summer, with earlier migration in warmer years. We developed a statistical temperature model to forecast the timing and extent of upstream migration by pikeminnow under varying combinations of discharge and air temperature. Modeled river temperature increased with air temperature and downstream and decreased with discharge. In years with low discharge and high air temperature, we predict pikeminnow will move upstream earlier, increasing spatial and temporal overlap in their summer range with native fishes. Managing conditions that reduce pikeminnow co-occurrence with native fishes (i.e., decreasing river temperature) could increase amount and duration of predator-free habitat for native fishes. We predict invasive pikeminnow will have larger impacts on invaded riverine communities with global warming and increasing drought severity. Knowledge of life history and phenology, for pikeminnow and other organisms, can guide effective management as conditions change and help to limit adverse impacts of introduced organisms on native species. [ABSTRACT FROM AUTHOR]

Summary: Accounting for water limitation is key to determining vegetation sensitivity to drought. Quantifying water limitation effects on evapotranspiration (ET) is challenged by the heterogeneity of vegetation types, climate zones and vertically along the rooting zone.Here, we train deep neural networks using flux measurements to study ET responses to progressing drought conditions. We determine a water stress factor (fET) that isolates ET reductions from effects of atmospheric aridity and other covarying drivers. We regress fET against the cumulative water deficit, which reveals the control of whole‐column moisture availability.We find a variety of ET responses to water stress. Responses range from rapid declines of fET to 10% of its water‐unlimited rate at several savannah and grassland sites, to mild fET reductions in most forests, despite substantial water deficits. Most sensitive responses are found at the most arid and warm sites.A combination of regulation of stomatal and hydraulic conductance and access to belowground water reservoirs, whether in groundwater or deep soil moisture, could explain the different behaviors observed across sites. This variety of responses is not captured by a standard land surface model, likely reflecting simplifications in its representation of belowground water storage. [ABSTRACT FROM AUTHOR]

This paper is an attempt to study the cause and effect of the reported widespread decline in spring-flow from a catchment in the middle Himalaya in the Garhwal region. A range of statistical tests to the long rainfall data series is applied to the two gauge-based interpolated gridded data. A decline in annual and seasonal rainfall with a rising frequency of moderate to severe drought in the subseries (1961–2018) is observed compared to the first half of the 20th century. A sudden shift of declining trend is observed in IMD4 gridded data in the early to mid-sixties. Prolonged post-monsoon and winter recession characteristics are analysed through a single nonlinear model and a power-law model. The nonlinear model and event-based power-law recession analysis showed nonlinearity (B≠1) in a storage–discharge relationship at the spring catchment scale as well as the intercept (A) highlights a very fast-draining aquifer with a very short recession timescale. The log-transformed fitted single nonlinear modelled recession data revealed control of antecedent storage over the rate of outflow as parallel offset was observed in interannual prolonged recession curve in –dQ/dtvs. Q plot. Groundwater reservoir contributing to Ayal springflow is very vulnerable to reservoir storage changes. Research highlights: In recent time, threat to water sustainability in middle Himalaya is widely reported. However, a clear understanding of the cause is not being investigated in a systematic manner. The present study highlights that deficient monsoon years as well as dry winter months, are causing multi-year drought in middle Himalaya basins. Higher frequency of moderate drought is observed in the long-term rainfall data after the early to mid-sixties and may have caused the decline in springflow. Recession characteristics of springflow showed nonlinearity in storage–discharge relationship as well as very short recession time scale and springflow are extremely vulnerable to aquifer storage change. [ABSTRACT FROM AUTHOR]

Slow-moving landslides are widely observed in mountainous areas worldwide. While most of these landslides move slowly downslope over long periods of time, some ultimately accelerate rapidly and fail catastrophically. Simulating the landslide creep movement triggered by environmental factors such as precipitation, is therefore necessary to anticipate potential damaging effects on proximal infrastructure, habitat, and life. Here, we present a physically-based model that links pore-water pressure changes in the landslide mass with a new viscoplastic constitutive law designed to capture different temporal trends in slow-moving landslides. The model accounts for landslide velocity changes caused by rainfall infiltration through the Terzaghi's effective stress principle, thus directly resolving the deformation of the active shear zone. Calibration and validation of the computations benefited from both ground-based and remote sensing data for three active landslides in the California Coast Ranges, USA. We find that our model can accurately describe both slow quasi-continuous and episodic movement commonly displayed by active landslides. Although inherent limitations of the viscoplasticity framework did not enable us to describe catastrophic landslide acceleration, our model provides versatile tools that can be used to analyze and describe distinct types of slow-moving landslide dynamics. [ABSTRACT FROM AUTHOR]

Landscapes receive water from precipitation and then transport, store, mix, and release it, both downward to streams and upward to vegetation. How they do this shapes floods, droughts, biogeochemical cycles, contaminant transport, and the health of terrestrial and aquatic ecosystems. Because many of the key processes occur invisibly in the subsurface, our conceptualization of them has often relied heavily on physical intuition. In recent decades, however, much of this intuition has been overthrown by field observations and emerging measurement methods, particularly involving isotopic tracers. Here we summarize key surprises that have transformed our understanding of hydrological processes at the scale of hillslopes and drainage basins. These surprises have forced a shift in perspective from process conceptualizations that are relatively static, homogeneous, linear, and stationary to ones that are predominantly dynamic, heterogeneous, nonlinear, and nonstationary. Surprising observations and novel measurements are transforming our understanding of the hydrological functioning of landscapes. Even during storm peaks, streamflow is composed mostly of water that has been stored in the landscape for weeks, months, or years. Streamflow and tree water uptake often originate from different subsurface storages and from different seasons' precipitation. Stream networks dynamically extend and retract as the landscape wets and dries, and many stream reaches lose flow into underlying aquifers. [ABSTRACT FROM AUTHOR]

Mediterranean regions are hot spots of climate change, where the expected decrease in water resources threatens the sustainability of shrublands at their arid margins. Studying spectral vegetation indices' relationships with rainfall and potential evapotranspiration (PET) changes across Mediterranean to arid transition zones is instrumental for developing methods for mapping and monitoring the effects of climate change on desert fringe shrublands. Here we examined relationships between 17 spectral vegetation indices (VIs) and four climate and aridity measures, i.e., rainfall, PET, aridity index (AI), and water deficit (WD), calculated at accumulation lags between 1 and 6 months. For this purpose, VIs for 38 sites (100 × 100 m each) representing less disturbed areas were extracted from Sentinel 2A images for 3 years with high (2016), low (2017), and average (2018) annual rainfall. Most of the VIs had shown the highest correlation with the four climate and aridity measures at 2-month accumulation interval. While NDVI relationships with climate measures gained the widest use, our data suggest that indices combining NIR and SWIR bands better correlate with climate parameters. AI is one of the leading annual measures of dryness worldwide; when calculating it monthly, WD was found to represent better the balance between precipitation and PET across the climate transition zone and to be better correlated with VIs. Relationships between NIR and SWIR VIs and water deficit may thus facilitate improvements in monitoring and mapping desert fringe shrublands' responses to climate change if supported by similar results from other areas. [ABSTRACT FROM AUTHOR]

Climate change is increasing the severity and duration of drought events experienced by forest ecosystems. Because water is essential for tree physiological processes, the ability of trees to survive prolonged droughts will largely depend on whether they have access to reliable water sources. While many woody plant species exhibit the ability to shift water sources between different depths of soil and rock water in response to changes in climate and water availability, it is unclear if Sierra Nevada conifers exhibit this plasticity. Here we analysed the δ18O and δ13C values of annual tree rings to determine the water-use patterns of large Sierra Nevada conifers during the 2012–16 California drought and 4 years before this drought event (2004–07). We analysed four species (Pinus jeffreyi Grev. & Balf. (Jeffrey pine), Pinus lambertiana Dougl. (sugar pine), Abies concolor (Gord. & Glend.) Lindl. Ex Hilderbr (white fir) and Calocedrus decurrens (Torr.) Florin (incense-cedar)) across a range of topographic positions to investigate differences in water-use patterns by species and position on the landscape. We found no significant differences in δ18O and δ13C values for the pre-drought and drought periods. This stability in δ18O values suggests that trees did not shift their water-use patterns in response to the 2012–16 drought. We did find species-specific differences in water-use patterns, with incense-cedar exhibiting more depleted δ18O values than all other species. We also found trends that suggest the water source used by a tree may depend on topographic and growing environment attributes such as topographic wetness and the surrounding basal area. Overall, our results suggest that the water source used by trees varies by the species and topographic position, but that Sierra Nevada conifers do not switch their water-use patterns in response to the drought. This lack of plasticity could make Sierra Nevada conifers particularly vulnerable to drought mortality as their historically reliable water sources begin to dry out with climate change. [ABSTRACT FROM AUTHOR]

Vegetation hinders the acquisition of bedrock spectra and makes it difficult to classify bedrock with remote sensing data. Previous studies indicated bedrock can control vegetation growth through soluble nutrients and water-holding capacity. However, the potential of using vegetation spectral features to map bedrock has been rarely explored. This study first derived reflectance and vegetation indices from time series Sentinel-2 products, then did a spatiotemporal analysis of vegetation spectral features on different bedrock, and finally combined vegetation features and random forest classifiers to map bedrock. The results demonstrated that (a) the close relationship between vegetation growth and bedrock can be captured by Sentinel-2 images; (b) both VIs' combination and reflectance derived from the growing season can achieve reasonably classified maps, with classification accuracies of 70.06% and 73.46%, respectively; (c) NDVI was more sensitive to the bedrock than other VIs. Overall, vegetation spectral features showed great potential to map bedrock underneath vegetation. [ABSTRACT FROM AUTHOR]

Dynamic storage refers to groundwater storage that is sensitive to rainfall infiltration, streamflow generation, evapotranspiration, and other variables involving groundwater gain or loss. It plays a crucial role in habitat maintenance and the mitigation of environmental impacts on regional hydrological behaviors. Dynamic storage can be separated into direct storage, which contributes to the river channel, and indirect storage, which is insensitive to streamflow. The combination of diverse approaches would provide an estimation of the two storage types. This study estimated optimal baseflow coefficients and direct storage in the wet and dry seasons using an analytical streamflow duration curve model in eight catchments of the Choushui River Basin from 2013 to 2017. The water balance approach was then combined to assess indirect storage for evaluating seasonal dynamic storage components. The model applicability for each catchment of the Choushui River Basin in the wet and dry seasons was assessed using the similarity between observed and simulated flow duration curves, namely Kolmogorov–Smirnov distance. We also applied it to assess the performance difference between model and streamflow recession analysis, which is typically used to estimate baseflow coefficients. The results demonstrated that seasonal differences in baseflow coefficients were related to catchment characteristics as well as the aquifer extent through which groundwater flows. The model utilizing maximum likelihood estimation exhibited superior performance than streamflow recession analysis and was highly applicable in our study area in wet and dry seasons. Dynamic storage components demonstrated a considerable difference in the additional groundwater storage between dry and wet seasons and a loss of direct storage was observed in most catchments during the dry season. [ABSTRACT FROM AUTHOR]

Bedrock weathering performs a significant influence on the evolution of Earth's critical zone. Carbonate rock (dolostone), metamorphic rock (gneiss), and sedimentary rock (sandstone) geological formations in Yanshan Mountain, Hebei Province, are taken as objects to probe the controlling of geological formations on weathering characteristics, migration, and enrichment of elements as well as structure of Earth's critical zone under the identical climate conditions through geological field survey, analysis on minerals component, element distribution in the weathering profile. The dolostone geological formation (DGF) is lithologically dominated by dolostone, characterized by the strongest and predominant chemical weathering. During bedrock weathering and pedogenesis, DGF is marked by significant depletion of CaO, MgO, S, Mn, Mo and enrichment of N, K, Fe2O3, and Zn with concentrations of P, Cu, and B keeping stable. Shortage of soil-forming materials and significant loss are driven by soil erosion, which results in thin regolith and soil. The soil thickness is less than 10 cm, and the regolith thickness is less than 30 cm. The vegetation community is predominantly rock arbor or brush, which is calcivorous and tolerant of barrenness. Plagiogneiss is a dominant rock type of gneiss geological formation (GGF), characterized by the weakest weathering and fast chemical and physical weathering rate. GGF is masked by significant depletion of P, K, CaO, MgO, Fe2O3, Mn, Cu and enrichment of N, S, Mo, and B, with contents of Zn keeping stable. Both soil and regolith developed in GGF are relatively thick for one of the reasons that biotite expands during weathering. The soil thickness is more than 50 cm, and the regolith thickness ranges from 100 to 200 cm. The vegetation community is predominantly high-quality economic forests and various arbors because of the enrichment of nutrients in GGF. Sandstone is primarily a rock type of sandstone geological formation (SGF), characterized by moderate weathering degree and slow chemical weathering rate. SGF is marked by significant depletion of P, K, CaO, MgO, Fe2O3, and enrichment of N, S, Mn, Cu, Zn, and Mo, with fluctuant changes of Zn and B. The thickness of soil developed in SGF varies between that of DGF and GGF. The soil thickness ranges from 30 to 50 cm, and the regolith thickness ranges from 50 to 100 cm. Chinese pines are widely spread on the shady slopes of SGF. Research provides theoretical support for screening dominant ecological resource areas, ecological industry development and ecological protection and restoration for Yanshan Mountain, Hebei Province. [ABSTRACT FROM AUTHOR]

Understanding the subsurface structure and function in the near-surface groundwater system, including fluid flow, geomechanical, and weathering processes, requires accurate predictions of the spatial distribution of petrophysical properties, such as rock and fluid (air and water) volumetric fractions. These properties can be predicted from geophysical measurements, such as electrical resistivity tomography and refraction seismic data, by solving a rock physics inverse problem. A Bayesian inversion approach based on a Monte Carlo implementation of the Bayesian update problem is developed to generate multiple realizations of porosity and water saturation conditioned on geophysical data. The model realizations are generated using a geostatistical algorithm and updated according to the ensemble smoother approach, an efficient Bayesian data assimilation technique. The prior distribution includes a spatial correlation function such that the model realizations mimic the geological spatial continuity. The result of the inversion includes a set of realizations of porosity and water saturation, as well as the most likely model and its uncertainty, that are crucial to understand fluid flow, geomechanical, and weathering processes in the critical zone. The proposed approach is validated on two synthetic datasets motivated by the Southern Sierra Critical Zone Observatory and is then applied to data collected on a mountain hillslope near Laramie, Wyoming. The inverted results match the measurements, honor the spatial correlation prior model, and provide geologically realistic petrophysical models of weathered rock at Earth's surface. [ABSTRACT FROM AUTHOR]

Climate change is becoming more and more remarkable which has an obvious impact on crop yields all over the world. Future climate scenario data was simulated by 5 climate models recommended by ISI-MIP under 4 RCP scenarios, in which the approximate scenarios with global warming by 1.5 °C and 2 °C were selected. Applying DSSAT and GTAP models, the per unit yield changes of maize in the world under global warming by 1.5 °C and 2.0 °C were analyzed and the market prices of maize at national and global levels were simulated. The results showed that, the risk of maize yield reduction under 2.0 °C scenario was much more serious than 1.5 °C scenario; the ratios of yield changes were separately 0.18% and − 10.8% under 1.5 °C and 2.0 °C scenarios. The reduction trend of total maize production is obvious in the top five countries and the main producing regions of the world, especially under the 2.0 °C scenario. The market price of maize would increase by around 0.7% and 3.4% under 1.5 °C and 2.0 °C scenarios. With the quickly increasing population in the world, it is urgent for all countries to pay enough attention to the risk of maize yield and take actions of mitigation and adaptation to climate change. [ABSTRACT FROM AUTHOR]

The unfolding climate crisis is in many respects a human issue, one caused by anthropogenic emissions of CO2 to the atmosphere, and that can only be solved through a concerted effort across all sectors of society. In this prospective synthesis, I explain how expanding the scope of biogeochemical research would lead to a more rigorous and impactful climate change mitigation and adaptation agenda. Focusing on biogeochemistry as an area of interdisciplinary convergence, I review theories and empirical studies in the environmental and social sciences, to distill five principles and three phases of implementation for sustainable carbon capture projects. I discuss how land conservation, management, and restoration might be coordinated to prepare for climate change and to achieve multiple social and ecological benefits, including enhanced carbon drawdown and permanence on land. On the conservation front, the abundance of threatened plant and animal species spatially correlates with the distribution of carbon- and water-rich habitats within and across key regions, which can be prioritized for biodiversity protection with major climatic benefits. On the management front, long-term records of socioecological change warrant a revision of current models for sustainable forestry and agriculture in favor of decentralized system-specific prescriptions, including interventions where organic or inorganic carbon capture may improve wood and food production under future climate scenarios. On the restoration front, experiments in degraded landscapes reveal mechanisms of carbon stabilization, such as iron-coordination of organic complexes, which amplify the benefits of ecological succession and lead to carbon accumulation beyond thresholds predicted for undisturbed ecosystems. These examples illustrate the potential for innovation at the intersection of basic and applied biogeoscience, which could accelerate atmospheric carbon capture through new discoveries and collective action. [ABSTRACT FROM AUTHOR]

Purpose: Isotope-based root water uptake analysis usually involves cryogenic vacuum extraction (CVE) of water from soil and other water-holding materials, according to the assumption that no isotopic fractionation occurs during the related processes. Recently, a growing body of literature identified isotopic deviations that were caused by CVE. However, the isotopic deviations of water extracted from carbonate soils by CVE are undefined, which prohibits dependable utilization of stable water isotopes in CVE involved studies, especially in karst regions. Methods: Three types of water-holding material, weathered carbonate bedrock, typical karst soils that were kept intact or washed with diluted HCL thus with varying levels of carbonate content were oven-dried and spiked with various amounts of reference water. The recovery of known isotope values was tested in all rewetted samples by using one CVE system. Results: No significant differences were detected between the isotope values of the water extracted from the weathered carbonate bedrock and the input water. However, isotope values of water extracted from the soils were significantly more negative than the input water. Moreover, the magnitude of δD deviation was highly related to soil water content, while the magnitude of δ18O values was strongly dependent on the amount of carbonate present. Conclusions: Considering the isotopic deviations caused by CVE and the obstacles associated with the calibration process, the application of an isotope-based method that involves CVE needs to be adapted to the specific properties of karst regions. [ABSTRACT FROM AUTHOR]

Summary: Forests are a critical carbon sink and widespread tree mortality resulting from climate‐induced drought stress has the potential to alter forests from a carbon sink to a source, causing a positive feedback on climate change. Process‐based vegetation models aim to represent the current understanding of the underlying mechanisms governing plant physiological and ecological responses to climate. Yet model accuracy varies across scales, and regional‐scale model predictive skill is frequently poor when compared with observations of drought‐driven mortality. I propose a framework that leverages differences in model predictive skill across spatial scales, mismatches between model predictions and observations, and differences in the mechanisms included and absent across models to advance the understanding of the physiological and ecological processes driving observed patterns drought‐driven mortality. [ABSTRACT FROM AUTHOR]

Background and Aims Gypsum drylands are widespread worldwide. In these arid ecosystems, the ability of different species to access different water sources during drought is a key determining factor of the composition of plant communities. Gypsum crystallization water could be a relevant source of water for shallow-rooted plants, but the segregation in the use of this source of water among plants remains unexplored. We analysed the principal water sources used by 20 species living in a gypsum hilltop, the effect of rooting depth and gypsum affinity, and the interaction of the plants with the soil beneath them. Methods We characterized the water stable isotope composition, δ 2H and δ 18O, of plant xylem water and related it to the free and gypsum crystallization water extracted from different depths throughout the soil profile and the groundwater, in both spring and summer. Bayesian isotope mixing models were used to estimate the contribution of water sources to plant xylem sap. Key Results In spring, all species used free water from the top soil as the main source. In summer, there was segregation in water sources used by different species depending on their rooting depth, but not on their gypsum affinity. Gypsum crystallization water was the main source for most shallow-rooted species, whereas free water from 50 to 100 cm depth was the main source for deep-rooted species. We detected plant–soil interactions in spring, and indirect evidence of possible hydraulic lift by deep-rooted species in summer. Conclusions Plants coexisting in gypsum communities segregate their hydrological niches according to their rooting depth. Crystallization water of gypsum represents an unaccounted for, vital source for most of the shallow-rooted species growing on gypsum drylands. Thus, crystallization water helps shallow-rooted species to endure arid conditions, which eventually accounts for the maintenance of high biodiversity in these specialized ecosystems. [ABSTRACT FROM AUTHOR]

Background: Water migration and use are important processes in trees. However, it is possible to overestimate transpiration by equating the water absorbed through the plant roots to that diffused back to the atmosphere through stomatal transpiration. Therefore, it is necessary to quantify the water transpired and stored in plants. Method: The δ2H/δ18O technique and heat ratio method were used to explore the water usage of coniferous and broad-leaved tree species, including the proportions of water used for transpiration and water storage. Results: Platycladus orientalis and Quercus variabilis had strong plasticity in their water usage from different sources. Platycladus orientalis primarily used groundwater (30.5%) and the 60–100-cm soil layer (21.6%) throughout the experimental period and was sensitive to precipitation, absorbing water from the 0–20-cm layer (26.6%) during the rainy season. Quercus variabilis absorbed water from all sources (15.7%–36.5%) except from the 40–60-cm soil layer during the dry season. In addition, it did not change its water source but increased its groundwater uptake during the rainy season. The annual mean water fluxes of P. orientalis and Q. variabilis were 374.69 and 469.50 mm·year− 1, with 93.49% and 93.91% of the water used for transpiration, respectively. However, nocturnal sap flow in P. orientalis and Q. variabilis was mainly used for water storage in the trunk rather than transpiration, which effectively alleviated drought stress and facilitated the transport of nutrients. Conclusions: The water stored in both species comprised 6%–7% of the total water fluxes and, therefore, should be considered in water balance models. [ABSTRACT FROM AUTHOR]

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Groundwater resources of mountainous basins are particularly important for maintaining the ecological environment and downstream domestic water demands. Quantitative analysis of the groundwater balance in a mountainous area is very important for monitoring and management of groundwater resources. Conventional analysis methods usually require extensive field investigation for estimation of hydrogeological parameters, which can be challenging in a mountainous basin. This study applied a series of methods based on daily streamflow data to estimate the groundwater balance of the Tao'er River Basin in Northeast China and also analyzed the response characteristics of effective groundwater recharge to rainfall. The results showed that groundwater recharge in the Tao'er River Basin occurs mainly through rainfall percolation in summer, and that groundwater is rapidly discharged in the form of baseflow and evapotranspiration. Baseflow discharge accounted for ~ 93% of recharge, whereas evapotranspiration accounted for the remaining ~ 7%. The multi-year average effective groundwater recharge values of the Chaersen, Suolun, Dashizhai and Zhenxi sub-basins were 59.7 mm, 62.4 mm, 19.6 mm and 34.6 mm, respectively. Groundwater recharge showed a slow and weak response to rainfall before the rainiest month (January–July). In general, the recharge peak appeared ~ 4 days after a rainfall event, and the recharge process continued for 13–16 days. However, the response was relatively rapid and obvious after the rainiest month (August to December). The recharge peak appeared ~ 3 days after a rainfall event, and the recharge process continued for 7–9 days. [ABSTRACT FROM AUTHOR]

Nearshore (littoral) habitats of clear lakes with high water quality are increasingly experiencing unexplained proliferations of filamentous algae that grow on submerged surfaces. These filamentous algal blooms (FABs) are sometimes associated with nutrient pollution in groundwater, but complex changes in climate, nutrient transport, lake hydrodynamics, and food web structure may also facilitate this emerging threat to clear lakes. A coordinated effort among members of the public, managers, and scientists is needed to document the occurrence of FABs, to standardize methods for measuring their severity, to adapt existing data collection networks to include nearshore habitats, and to mitigate and reverse this profound structural change in lake ecosystems. Current models of lake eutrophication do not explain this littoral greening. However, a cohesive response to it is essential for protecting some of the world's most valued lakes and the flora, fauna, and ecosystem services they sustain. [ABSTRACT FROM AUTHOR]

In the past several decades, field studies have shown that woody plants can access substantial volumes of water from the pores and fractures of bedrock1–3. If, like soil moisture, bedrock water storage serves as an important source of plant-available water, then conceptual paradigms regarding water and carbon cycling may need to be revised to incorporate bedrock properties and processes4–6. Here we present a lower-bound estimate of the contribution of bedrock water storage to transpiration across the continental United States using distributed, publicly available datasets. Temporal and spatial patterns of bedrock water use across the continental United States indicate that woody plants extensively access bedrock water for transpiration. Plants across diverse climates and biomes access bedrock water routinely and not just during extreme drought conditions. On an annual basis in California, the volumes of bedrock water transpiration exceed the volumes of water stored in human-made reservoirs, and woody vegetation that accesses bedrock water accounts for over 50% of the aboveground carbon stocks in the state. Our findings indicate that plants commonly access rock moisture, as opposed to groundwater, from bedrock and that, like soil moisture, rock moisture is a critical component of terrestrial water and carbon cycling.Woody plants across the continental United States make extensive use of water stored in bedrock across diverse climates and biomes. [ABSTRACT FROM AUTHOR]

Invasive species are a global threat to ecosystem biodiversity and function; non-native grass invasion has been particularly problematic in sparsely vegetated ecosystems such as open dunes. Native plant population responses to invasion, however, are infrequently translated to landscape scales, limiting the effectiveness of these data for addressing conservation issues. We quantified population density, total population size, and age class distribution of the federally-endangered plant species Antioch Dunes evening primrose (Oenothera deltoides subsp. howellii), at sites along a non-native grass invasion gradient in California, USA. We then scaled relationships between invasion and plant density across the species' range using spatial models and remote sensing data. Adult and juvenile O. deltoides subsp. howellii densities were more than 10 times higher in non-invaded areas (grids with 10% total plant cover) when compared to highly-invaded areas (grids with 80% total plant cover). The ratio of O. deltoides subsp. howellii juveniles to adults decreased to less than 1 at 54% total cover, highlighting sensitivity of the regeneration niche to invasion. Spatial models mapped hotspots of O. deltoides subsp. howellii abundance and population structure across the landscape at sub-meter scales. Scaling the impacts of increasing invasion on plant species of conservation concern holds promise when coupled with remote sensing approaches, especially in naturally low-cover ecosystems where readily available metrics (e.g., Normalized Difference Vegetation Index) can be used to quantify invasion. These spatial models inform how future invasive species management may influence population size and spatial distribution of species of conservation concern. [ABSTRACT FROM AUTHOR]

The Kings River Experimental Watersheds (KREW) were established in 2002 to expand our knowledge of catchment physical, chemical, and biological processes in Sierra Nevada headwater forests, and to better understand the impacts of prescribed burning and forest thinning on these processes. Two elevation strata (high and low) were selected for the KREW sites, with four independent catchments and one nested catchment within each stratum. Both high and low elevation study areas were instrumented for continuous measurements of meteorology, streamflow, and turbidity. Atmospheric and stream chemistry, suspended sediment concentration, and bedload sediment delivery were measured on a regular schedule. Soil chemical and physical properties and vegetation were systematically sampled before and after the initial thinning and prescribed burning treatments, which were implemented between 2012 and 2016. Post‐treatment data collection continues today as we explore opportunities for the second round of possible treatments. The critical research infrastructure and long‐term baseline data collection has been instrumental in building partnerships with downstream managers, end users, non‐governmental organizations, academic researchers, and national research programmes. Contributions to date include fundamental understanding of magnitude and variability of nutrient deposition; carbon, nutrient, and major ion dynamics in headwater streams; aquatic algae and macroinvertebrate populations; vegetation composition and structure; and streamflow responses to precipitation in the two elevation strata. Data from the experimental watersheds also support calibration and validation of diverse hydrologic models used for water resources planning. [ABSTRACT FROM AUTHOR]

Stream networks expand and contract through time, impacting chemical export, aquatic habitat, and water quality. Although recent advances improve prediction of the extent of the wetted channel network (L) based on discharge at the catchment outlet (Q), controls on the temporal variability of L remain poorly understood and unquantified. Here we develop a quantitative, conceptual framework to explore how flow regime and stream network hydraulic scaling factors co‐determine the relative temporal variability in L (denoted here as the total wetted channel drainage density). Network hydraulic scaling determines how much L changes for a change in Q, while the flow regime describes how Q changes in time. We compiled datasets of co‐located dynamic stream extent mapping and discharge to analyze all globally available empirical data using the presented framework. We found that although variability in L is universally damped relative to variability in Q (i.e., streamflow is relatively more variable in time than network extent), the relationship is elastic, meaning that for a given increase in the variability in Q, headwater catchments will experience greater‐than‐proportional increases in the variability of L. Thus, under anticipated climatic shifts towards more volatile precipitation, relative variability in headwater stream network extents can be expected to increase even more than the relative variability of discharge itself. Comparison between network extents inferred from the L‐Q relationship and blue lines on USGS topographic maps shows widespread underestimation of the wetted channel network by the blue line network. [ABSTRACT FROM AUTHOR]

Purpose: As soil hydraulic characteristics, including near-saturated hydraulic conductivity and water retention, influence slope stability and erosion development, this study aimed at the spatial distribution patterns of hydraulic properties along the Benggang slopes for a better understanding of the development mechanisms of Benggang erosion in southern China. Materials and methods: Near-saturated hydraulic conductivity and soil water retention at different slope positions in two typical Benggang erosional areas were determined by the in situ infiltration test using tension disk infiltrometer and laboratory test using the high-speed freezing centrifuge method. Results and discussion: The soil hydraulic conductivity, effective macropore, and pore size parameter, Gardner α, in lower slopes were greater than those in upper and middle slopes. From upper to lower slope, the total water flow showed an increasing trend in pores > 1 mm in diameter, in contrast to a decrease in pores between > 0.33 mm and < 0.5 mm in diameter, and < 0.33 mm in diameter. The effective macroporosity values in measured soils were statistically greater (p < 0.05) in the lower slope than in the upper or middle slope. Meanwhile, the soil water retention of lower slopes was lower than that of upper and middle slopes, and the lower slope had higher unsaturated hydraulic conductivity than the upper or middle slope. Erosion degree showed significant (p < 0.05, p = 0.016) influence on the soil hydraulic conductivity and effective macropore. Moreover, the soils on the severe erosion slope drain faster than that on the slight erosion slope, and the unsaturated hydraulic conductivity decreased faster on the severe erosion slope than on the slight erosion slope. Conclusions: Vertical differentiation of granitic soil properties is the main factor influencing the soil hydraulic properties of the two slopes with a different erosion degree, while the macropores are the main factor influencing the soil hydraulic properties in different slope positions. Spatial variation may affect the rainwater infiltration during rainfall and soil water redistribution after the rainfall and finally affect the soil mass failure of the collapsing wall. [ABSTRACT FROM AUTHOR]

Summary: Drought‐induced tree mortality frequently occurs in patches with different spatial and temporal distributions, which is only partly explained by inter‐ and intraspecific variation in drought tolerance. We investigated whether bedrock properties, with special reference to rock water storage capacity, affects tree water status and drought response in a rock‐dominated landscape.We measured primary porosity and available water content of breccia (B) and dolostone (D) rocks. Saplings of Fraxinus ornus were grown in pots filled with soil or soil mixed with B and D rocks, and subjected to an experimental drought. Finally, we measured seasonal changes in water status of trees in field sites overlying B or D bedrock.B rocks were more porous and stored more available water than D rocks. Potted saplings grown with D rocks had less biomass and suffered more severe water stress than those with B rocks. Trees in sites with B bedrock had more favourable water status than those on D bedrock which also suffered drought‐induced canopy dieback.Bedrock represents an important water source for plants under drought. Different bedrock features translate into contrasting below‐ground water availability, leading to landscape‐level heterogeneity of the impact of drought on tree water status and dieback. [ABSTRACT FROM AUTHOR]

During the South-American Monsoon season, deep convective systems occur at the eastern flank of the Central Andes leading to heavy rainfall and flooding. We investigate the large- and meso-scale atmospheric dynamics associated with extreme discharge events (> 99.9th percentile) observed in two major river catchments meridionally stretching from humid to semi-arid conditions in the southern Central Andes. Based on daily gauge time series and ERA-Interim reanalysis, we made the following three key observations: (1) for the period 1940–2016 daily discharge exhibits more pronounced variability in the southern, semi-arid than in the northern, humid catchments. This is due to a smaller ratio of discharge magnitudes between intermediate (0.2 year return period) and rare events (20 year return period) in the semi-arid compared to the humid areas; (2) The climatological composites of the 40 largest discharge events showed characteristic atmospheric features of cold surges based on 5-day time-lagged sequences of geopotential height at different levels in the troposphere; (3) A subjective classification revealed that 80% of the 40 largest discharge events are mainly associated with the north-northeastward migration of frontal systems and 2/3 of these are cold fronts, i.e. cold surges. This work highlights the importance of cold surges and their related atmospheric processes for the generation of heavy rainfall events and floods in the southern Central Andes. [ABSTRACT FROM AUTHOR]

Background: The paper by Korboulewsky and co-authors in this issue of Plant and Soil address some of the central questions of critical zone ecohydrology: how do plants interact with rocks that exclude roots but hold plant-available water? Scope: I compare plant water uptake from stony soils and fractured bedrock in the critical zone, suggesting that the two cases may represent endpoints of a continuum along which the proportion of available space for root growth changes. Conclusions: Rhizosphere models could be improved and generalized by structuring the layers of the critical zone into volume fractions that can be rooted and fractions from which roots are excluded. I hypothesize that plant-available water capacity of the rooted fraction governs productivity, while plant-available water in the unrooted fraction governs drought resilience. [ABSTRACT FROM AUTHOR]

The preservation of life history and other phenotypic complexity is central to the resilience of Pacific salmon stocks. Steelhead (Oncorhynchus mykiss) express a diversity of life-history strategies such as the propensity to migrate (anadromy/residency) and the timing and state of maturation upon return to freshwater (run-timing), providing an opportunity to study adaptive phenotypic complexity. Historically, the Eel River supported upwards of 1 million salmon and steelhead, but the past century has seen dramatic declines of all salmonids in the watershed. Here we investigate life-history variation in Eel River steelhead by using Rapture sequencing, on thousands of individuals, to genotype the region diagnostic for run-timing (GREB1L) and the region strongly associated with residency/anadromy (OMY5) in the Eel River and other locations, as well as determine patterns of overall genetic differentiation. Our results provide insight into many conservation-related issues. For example, we found that distinct segregation between winter and summer-run steelhead correlated with flow-dependent barriers in major forks of the Eel, that summer-run steelhead inhabited the upper Eel prior to construction of an impassable dam, and that both life history and overall genetic diversity have been maintained in the resident trout population above; and we found no evidence of the summer-run allele in the South Fork Eel, indicating that summer run-timing cannot be expected to arise from standing genetic variation in this and other populations that lack the summer-run phenotype. The results presented in this study provide valuable information for designing future restoration and management strategies for O. mykiss in Northern California and beyond. [ABSTRACT FROM AUTHOR]

Understanding causes of interpersonal conflicts, related costs, and the effects on investment in agriculture are important concerns of social sciences. The present study was designed to explore these aspects in relation to climate change, since rising temperature and precipitation are considered crucial causal factors in fueling interpersonal conflicts. The study used cross-sectional data collected from rural farm households from a large district of Pakistani Punjab. Cost of conflicts was estimated using standard economic methods whereas factors affecting interpersonal conflicts were estimated through employing logit model. The study found that interpersonal conflicts cost US$135 per month for following the proceedings of the conflicts filed in the court. Households involved in conflicts spent significantly very few resources in purchasing farm inputs which in turn declined productivity of maize (28%) and sugarcane (19%). Warm temperature, precipitation, and windstorm were perceived by households as causal factors for interpersonal conflicts. Socioeconomic characteristics namely, farm size, livestock, family size, and high monthly income of household, were significantly associated with interpersonal conflicts. The study concludes important policy implications. [ABSTRACT FROM AUTHOR]

Summary: The emergence of critical zone (CZ) science has provided an integrative platform for investigating plant ecophysiology in the context of landscape evolution, weathering and hydrology. The CZ lies between the top of the vegetation canopy and fresh, chemically unaltered bedrock and plays a pivotal role in sustaining life. We consider what the CZ perspective has recently brought to the study of plant ecophysiology. We specifically highlight novel research demonstrating the importance of the deeper subsurface for plant water and nutrient relations. We also point to knowledge gaps and research opportunities, emphasising, in particular, greater focus on the roles of deep, nonsoil resources and how those resources influence and coevolve with plants as a frontier of plant ecophysiological research. [ABSTRACT FROM AUTHOR]

The recession identity is an essential indicator of river performance, health and diminution status. This study, therefore, presents an assessment of streamflow recession characteristics in relation to the hydrostratigraphy property of watershed. The streamflow recession assessment was carried out by computing the flow duration curve (FDC) and baseflow index (BFI) analyses of 28 year streamflow records at six distinct streamflow gauging stations. Digital processed aeromagnetic map was hybridized with geological survey and map review for the construction and characterization of concise watershed surficial lithology. The FDC plot of low-flow slopes and Q95 reported the flow per station as thus; Buffalo (− 0.0113; 0.0026), Tshoxa (− 0.0029, 0.0016), Yellowwoods (− 0.0022, 0.0008), Mgqakwebe (− 0.0017, 0.0007), Quencwe (− 0.0009, 0.0002), and Ngqokweni (− 0.0005, 0.0001). Similarly, BFI results show the following rank: Buffalo (0.541), Yellowwoods (0.488), Tshoxa (0.450), Mgqakwebe (0.443), Quencwe (0.415), and Ngqokweni (0.332). The recession analysis revealed that the Q95 slope of the stochastic FDC approach is a more reliable recession estimate for environmental flow. The assessment of the recession–lithology relationship suggests that the porosity network of the contact zone and fracture system of dolerite may produce a weightier impact of baseflow discharge in support of environmental flow over the hydraulic conductivity of sandstone. The physiographic trends of streamflow response suggest the influence of the high relief on streamflow flux. The overall results suggest that the hybrid approach of FDC and BFI analyses are highly effective for replicating the streamflow recession at the catchment stage and could be adopted for investigation of river sustainability. [ABSTRACT FROM AUTHOR]

Current models of vegetation pattern formation rely on a system of weakly nonlinear reaction-diffusion equations that are coupled by their source terms. While these equations, which are used to describe a spatiotemporal planar evolution of biomass and soil water, qualitatively capture the emergence of various types of vegetation patterns in arid environments, they are phenomenological and have a limited predictive power. We ameliorate these limitations by deriving the vertically averaged Richards' equation to describe flow (as opposed to 'diffusion') of water in partially saturated soils. This establishes conditions under which this nonlinear equation reduces to its weakly nonlinear reaction-diffusion counterpart used in the previous models, thus relating their unphysical parameters (e.g., diffusion coefficient) to the measurable soil properties (e.g., hydraulic conductivity) used to parameterize the Richards equation. Our model is valid for both flat and sloping landscapes and can handle arbitrary topography and boundary conditions. The result is a model that relates the environmental conditions (e.g., precipitation rate, runoff and soil properties) to formation of multiple patterns observed in nature (such as stripes, labyrinth and spots). [ABSTRACT FROM AUTHOR]

Objective: Marijuana (Cannabis spp.) growing operations (MGO) in California have increased substantially since the mid-1990s. One environmental side-effect of MGOs is the extensive use of anticoagulant rodenticides (AR) to prevent damage to marijuana plants caused by wild rodents. In association with a long-term demographic study, we report on an observation of brodifacoum AR exposure in a threatened species, the northern spotted owl (Strix occidentalis caurina), found freshly dead within 669–1347 m of at least seven active MGOs. Results: Liver and blood samples from the dead northern spotted owl were tested for 12 rodenticides. Brodifacoum was the only rodenticide detected in the liver (33.3–36.3 ng/g) and blood (0.48–0.54 ng/ml). Based on necropsy results, it was unclear what role brodifacoum had in the death of this bird. However, fatal AR poisoning has been previously reported in owls with relatively low levels of brodifacoum residues in the liver. One likely mechanism of AR transmission from MGOs to northern spotted owls in California is through ingestion of AR contaminated prey that frequent MGOs. The proliferation of MGOs with their use of ARs in forested landscapes used by northern spotted owls may pose an additional stressor for this threatened species. [ABSTRACT FROM AUTHOR]