Simulating the Cascading Effects of an Extreme Agricultural Production Shock: Global Implications of a Contemporary US Dust Bowl Event

Higher temperatures expected by midcentury increase the risk of shocks to crop production, while the interconnected nature of the current global food system functions to spread the impact of localized production shocks throughout the world. In this study, we analyze the global potential impact of a present-day event of equivalent magnitude to the US Dust Bowl, modeling the ways in which a sudden decline in US wheat production could cascade through the global network of agricultural trade. We use observations of country-level production, reserves, and trade data in a Food Shock Cascade model to explore trade adjustments and country-level inventory changes in response to a major, multiyear production decline. We find that a 4-year decline in wheat production of the same proportional magnitude as occurred during the Dust Bowl greatly reduces both wheat supply and reserves in the United States and propagates through the global trade network. By year 4 of the event, US wheat exports fall from 90.5 trillion kcal before the drought to 48 trillion to 52 trillion kcal, and the United States exhausts 94% of its reserves. As a result of reduced US exports, other countries meet their needs by leveraging their own reserves, leading to a 31% decline in wheat reserves globally. These findings demonstrate that an extreme production decline would lead to substantial supply shortfalls in both the United States and in other countries, where impacts outside the United States strongly depend on a country's reserves and on its relative position in the global trade network

Methods For Detecting Early Warnings Of Critical Transitions In Time Series Illustrated Using Simulated Ecological Data

Many dynamical systems, including lakes, organisms, ocean circulation patterns, or financial markets, are now thought to have tipping points where critical transitions to a contrasting state can happen. Because critical transitions can occur unexpectedly and are difficult to manage, there is a need for methods that can be used to identify when a critical transition is approaching. Recent theory shows that we can identify the proximity of a system to a critical transition using a variety of so-called ‘early warning signals’, and successful empirical examples suggest a potential for practical applicability. However, while the range of proposed methods for predicting critical is rapidly expanding, opinions on their practical use differ widely, and there is no comparative study that tests the limitations of the different methods to identify approaching critical transitions using time-series data. Here, we summarize a range of currently available early warning methods and apply them to two simulated time series that are typical of systems undergoing a critical transition. In addition to a methodological guide, our work offers a practical toolbox that may be used in a wide range of fields to help detect early warning signals of critical transitions in time series data.Organismic and Evolutionary Biolog

The size-distribution of Earth’s lakes

Globally, there are millions of small lakes, but a small number of large lakes. Most key ecosystem patterns and processes scale with lake size, thus this asymmetry between area and abundance is a fundamental constraint on broad-scale patterns in lake ecology. Nonetheless, descriptions of lake size-distributions are scarce and empirical distributions are rarely evaluated relative to theoretical predictions. Here we develop expectations for Earth’s lake area-distribution based on percolation theory and evaluate these expectations with data from a global lake census. Lake surface areas ≥0.46 km2 are power-law distributed with a tail exponent (τ = 2.14) and fractal dimension (d = 1.4), similar to theoretical expectations (τ = 2.05; d = 4/3). Lakes <0.46 km2 are not power-law distributed. An independently developed regional lake census exhibits a similar transition and consistency with theoretical predictions. Small lakes deviate from the power-law distribution because smaller lakes are more susceptible to dynamical change and topographic behavior at sub-kilometer scales is not self-similar. Our results provide a robust characterization and theoretical explanation for the lake size-abundance relationship, and form a fundamental basis for understanding and predicting patterns in lake ecology at broad scales

Early Warning Signals of Ecological Transitions: Methods for Spatial Patterns

A number of ecosystems can exhibit abrupt shifts between alternative stable states. Because of their important ecological and economic consequences, recent research has focused on devising early warning signals for anticipating such abrupt ecological transitions. In particular, theoretical studies show that changes in spatial characteristics of the system could provide early warnings of approaching transitions. However, the empirical validation of these indicators lag behind their theoretical developments. Here, we summarize a range of currently available spatial early warning signals, suggest potential null models to interpret their trends, and apply them to three simulated spatial data sets of systems undergoing an abrupt transition. In addition to providing a step-by-step methodology for applying these signals to spatial data sets, we propose a statistical toolbox that may be used to help detect approaching transitions in a wide range of spatial data. We hope that our methodology together with the computer codes will stimulate the application and testing of spatial early warning signals on real spatial data

PENGARUH PERILAKU PEMERIKSA PAJAK DAN PROFESIONALISME PEMERIKSA PAJAK TERHADAP KINERJA PEMERIKSA PAJAK (Studi Pada KPP Pratama Bandung Karees )

ABSTRAK Penelitian ini bertujuan untuk mengetahui seberapa besar pengaruh perilaku pemeriksa pajak terhadap profesionalisme pemeriksa pajak dampaknya pada kinerja pemeriksa pajak dan untuk mengetahui seberapa besar pengaruh perilaku pemeriksa pajak dan profesionalisme pemeriksa pajak terhadap kinerja pemeriksa pajak . Metode penelitian yang digunakan adalah analisis deskriptif dan verifikatif. Populasi dari penelitian ini adalah pemeriksa pajak di KPP Pratama Bandung Karees yang berjumlah 30 responden. Te knik sampling yang digunakan adalah teknik sampling jenuh yaitu keseluruhan populasi dijadikan sampel penelitian. Analisis data dilakukan dengan menggunakan analisis path dan analisis regresi linier berganda. Hasil penelitian menunju k kan bahwa Perilaku Pemeriksa Pajak masuk ke dalam Kriteria cukup baik karena nilai rata - rata sebesar 33,77 berada pada interval 26,1 s/d 34. Secara parsial Perilaku Pemeriksa Pajak berpengaruh signifikan terhadap Kinerja Pemeriksa Pajak dengan kontribusi pengaruh sebesar 21, 6%. Profesionalisme Pemeriksa Pajak masuk ke dalam Kriteria cukup tinggi karena nilai rata - rata sebesar 47,8 berada pada interval 36,6 s/d 47,8 . Secara parsial Profesionalisme Pemeriksa Pajak berpengaruh signifikan terhadap Kinerja Pemeriksa Pajak dengan k ontribusi pengaruh sebesar 37,2%. Secara simultan Pengaruh Perilaku Pemeriksa Pajak dan Profesionalisme Pemeriksa Pajak terhadap Kinerja Pemeriksa Pajak adalah Perilaku Pemeriksa Pajak dan Profesionalisme Pemeriksa Pajak berpengaruh signifikan terhadap K inerja Pemeriksa Pajak dengan kontribusi pengaruh sebesar 59%. Pengaruh tidak langsung Perilaku Pemeriksa Pajak terhadap Kinerja Pemeriksa Pajak melalui Profesionalisme Pemeriksa Pajak sebesar 26,3%. Total pengaruh Perilaku Pemeriksa Pajak, Profesionalism e Pemeriksa Pajak terhadap Kinerja Pemeriksa Pajak sebesar 47,9%. Kata kunci : Perilaku Pemeriksa Pajak , Profesionalisme Pemeriksa Pajak dan Kinerja Pemeriksa Pajak

Reserves and trade jointly determine exposure to food supply shocks

While a growing proportion of global food consumption is obtained through international trade, there is an ongoing debate on whether this increased reliance on trade benefits or hinders food security, and specifically, the ability of global food systems to absorb shocks due to local or regional losses of production. This paper introduces a model that simulates the short-term response to a food supply shock originating in a single country, which is partly absorbed through decreases in domestic reserves and consumption, and partly transmitted through the adjustment of trade flows. By applying the model to publicly-available data for the cereals commodity group over a 17 year period, we find that differential outcomes of supply shocks simulated through this time period are driven not only by the intensification of trade, but as importantly by changes in the distribution of reserves. Our analysis also identifies countries where trade dependency may accentuate the risk of food shortages from foreign production shocks; such risk could be reduced by increasing domestic reserves or importing food from a diversity of suppliers that possess their own reserves. This simulation-based model provides a framework to study the short-term, nonlinear and out-of-equilibrium response of trade networks to supply shocks, and could be applied to specific scenarios of environmental or economic perturbations

Magnitude and Origin of CO2 Evasion From High-Latitude Lakes

Lakes evade significant amounts of carbon dioxide (CO2) to the atmosphere; yet the magnitude and origin of the evasion are still poorly constrained. We quantified annual CO2 evasion and its origin (in-lake net ecosystem production vs. lateral inputs from terrestrial ecosystems) in 14 high-latitude lakes through high-frequency estimates of open water CO2 flux and ecosystem metabolism and inorganic carbon mass-balance before and after ice breakup. Annual CO2 evasion ranged from 1 to 25 g C m(-2) yr(-1) of which an average of 57% was evaded over a short period at ice-breakup. Annual internal CO2 production ranged from -6 to 21 g C m(-2) yr(-1), of which at least half was produced over winter. The contribution of internal versus external source contribution to annual CO2 evasion varied between lakes, ranging from fully internal to fully external with most lakes having over 75% of the evasion sustained through a single source. Overall, the study stresses the large variability in magnitude and control of CO2 evasion and suggests that environmental change impacts on CO2 evasion from high-latitude lakes are not uniform

The volume and mean depth of Earth's lakes

Global lake volume estimates are scarce, highly variable, and poorly documented. We developed a rigorous method for estimating global lake depth and volume based on the Hurst coefficient of Earth's surface, which provides a mechanistic connection between lake area and volume. Volume‐area scaling based on the Hurst coefficient is accurate and consistent when applied to lake data sets spanning diverse regions. We applied these relationships to a global lake area census to estimate global lake volume and depth. The volume of Earth's lakes is 199,000 km3 (95% confidence interval 196,000–202,000 km3). This volume is in the range of historical estimates (166,000–280,000 km3), but the overall mean depth of 41.8 m (95% CI 41.2–42.4 m) is significantly lower than previous estimates (62–151 m). These results highlight and constrain the relative scarcity of lake waters in the hydrosphere and have implications for the role of lakes in global biogeochemical cycles

Bias in the shoreline development index: Ecological implications illustrated with an analysis of littoral-pelagic habitat coupling

We reexamined the relationship between the shoreline development index and metrics of habitat coupling using a bias-corrected variant of the shoreline development index. Our findings suggest that previously reported correlations may be artifacts of scale-dependent bias in shoreline development index measurements. The results highlight the need for careful measurement when seeking to understand links between lake morphology and ecological processes

Effects of Habitat-Specific Primary Production on Fish Size, Biomass, and Production in Northern Oligotrophic Lakes

Ecological theory predicts that the relative distribution of primary production across habitats influence fish size structure and biomass production. In this study, we assessed individual, population, and community-level consequences for brown trout (Salmo trutta) and Arctic char (Salvelinus alpinus) of variation in estimated habitat specific (benthic and pelagic) and total whole lake (GPP(whole)) gross primary production in 27 northern oligotrophic lakes. We found that higher contribution of benthic primary production to GPP(whole) was associated with higher community biomass and larger maximum and mean sizes of fish. At the population level, species-specific responses differed. Increased benthic primary production (GPP(Benthic)) correlated to higher population biomass of brown trout regardless of being alone or in sympatry, while Arctic char responded positively to pelagic primary production (GPP(Pelagic)) in sympatric populations. In sympatric lakes, the maximum size of both species was positively related to both GPP(Benthic) and the benthic contribution to GPP(Whole). In allopatric lakes, brown trout mean and maximum size and Arctic char mean size were positively related to the benthic proportion of GPP(Whole). Our results highlight the importance of light-controlled benthic primary production for fish biomass production in oligotrophic northern lakes. Our results further suggest that consequences of ontogenetic asymmetry and niche shifts may cause the distribution of primary production across habitats to be more important than the total ecosystem primary production for fish size, population biomass, and production. Awareness of the relationships between light availability and asymmetric resource production favoring large fish and fish production may allow for cost-efficient and more informed management actions in northern oligotrophic lakes