Individual Parcels Research Articles

Expanding networks of field hedges in densely populated landscapes in the Sahel

Changing woody plant density across agricultural landscapes of the Sudano-Sahelian region is a debated issue. This paper reports the results of an investigation on the contribution of field hedges to overall woody plant density. Hedges separating individual cropped parcels were studied within village agropastoral territories in the Dantiandou district in western Niger. In 1992, field hedges were mapped over the study area using aerial photography and in 2016, using high resolution Google Earth imagery. In 1992, field hedge length was equal to 1006 km within 435 km2 of croplands, equivalent to 2.3 km km−2. In 2016, 17.5% of these hedges had disappeared, but 1591 km of new hedges were observed resulting in an increased density of hedges to 5.6 km km−2. In 24 years, hedges had increased at a mean annual rate of 3.7% likely associated with the splitting of crop fields by inheritance.The composition and productivity of hedges were also monitored in 1996, 2010 and 2015. All trees (maximum height ≥ 4 m), shrubs (<4 m) and tussock perennial grasses were recorded within twelve field hedge samples of 200 m each. Field measurements were used to estimate basal area, crown area, foliage mass and wood mass of each woody plant within the sampled hedges. No significant trends were found between 1996 and 2015 in woody plant density, basal area, crown cover, wood and foliage masses across all monitored hedges. However, overall means hide a slight decrease in tree contributions, while shrub contributions first increased and then decreased. They also mask contradictory trends among sites most likely related to different rates of shrub coppicing and tree cutting. The woody species composition of the hedges is poor with an increase of Combretum glutinosum to the detriment of Guiera senegalensis over the study period.Multiplying the hedge sample statistics by the changing lengths of field hedges in the study area provides estimates of the contribution of the hedge woody plants to the woody plant population at a landscape scale. Between 1992 and 2016, field hedges contributed to increases of woody plant density by 3.9%, basal areas by 5.4%, crown cover by 2.7%, leading to 6.1% annual increase in foliage mass and 8.8% increase in wood mass.

A Lagrangian Ocean Model for Climate Studies

Most weather and climate models simulate circulations by numerically approximating a complex system of partial differential equations that describe fluid flow. These models also typically use one of a few standard methods to parameterize the effects of smaller-scale circulations such as convective plumes. This paper discusses the continued development of a radically different modeling approach. Rather than solving partial differential equations, the author’s Lagrangian models predict the motions of individual fluid parcels using ordinary differential equations. They also use a unique convective parameterization, in which the vertical positions of fluid parcels are rearranged to remove convective instability. Previously, a global atmospheric model and basin-scale ocean models were developed with this approach. In the present study, components of these models are combined to create a new global Lagrangian ocean model (GLOM), which will soon be coupled to a Lagrangian atmospheric model. The first simulations conducted with the GLOM examine the contribution of interior tracer mixing to ocean circulation, stratification, and water mass distributions, and they highlight several special model capabilities: (1) simulating ocean circulations without numerical diffusion of tracers; (2) modeling deep convective transports at low resolution; and (3) identifying the formation location of ocean water masses and water pathways.

Mapping Crop Calendar Events and Phenology-Related Metrics at the Parcel Level by Object-Based Image Analysis (OBIA) of MODIS-NDVI Time-Series: A Case Study in Central California

Remote sensing technology allows monitoring the progress of vegetation and crop phenology in large regions. Seasonal vegetation trends are commonly estimated from high temporal resolution but coarse spatial resolution satellite imagery, e.g., from MODIS-NDVI (Moderate Resolution Imaging Spectroradiometer—Normalized Difference Vegetation Index) time-series, which has usually limited their application to scenarios with few land uses or crops covering areas larger than actual parcel sizes. As an alternative, this paper proposes a general and robust procedure to map crop phenology at the level of individual crop parcels, and validates its feasibility in a complex and diverse cropland area located in central California. A first calibration phase consisted of evaluating the three curve-fitting models implemented in the TIMESAT software (i.e., asymmetric Gaussian (AG), double logistic (DL), and adaptive Savitzky–Golay (SG) filtering) and reporting the model and its settings that best adjusted to the MODIS-NDVI profile of each crop studied. Next, based on the selected crop-specific models and with a crop map previously obtained from ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) multi-temporal images, the procedure mapped four crop calendar events (i.e., start, end, middle, and length of the season) and five phenology-related metrics (i.e., base, maximum, amplitude, derivatives, and integrals of the NDVI values) of the study region by object-based image analysis (OBIA) of the MODIS-NDVI time-series. To mitigate the impact of mixed pixels, the OBIA procedure was designed to automatically apply a restrictive criterion based on the coverage of MODIS-NDVI pixels in each crop parcel: (1) using only the MODIS-NDVI pixels that were placed 100% within each crop parcel (i.e., “pure” pixels); or (2) if no “pure” pixels exist in any crop parcel, using only pixels with coverage percentages greater than 50%, and in such cases, reporting the mixing percentage in the output file. The calibration phase showed that the performance of the SG filtering was superior in most crops, with the exception of rice, while the AG model was intermediate in all of the cases. Differences between the dates of the start and end of the season that were observed in 120 ground-truth fields and the ones estimated by the crop-specific models were in a range of 11 days (for the corn fields) and 22 days (for the vineyard fields) on average. The OBIA procedure was also validated in 240 independent parcels with “pure” MODIS-NDVI pixels, reporting 89% and 82% of accuracy when mapping the start and end of the season, respectively. Our results revealed different growth patterns of the studied crops, especially of the crop calendar events of herbaceous (i.e., corn, rice, sunflower, and tomato) and woody crops (i.e., almond, walnut, and vineyard), of the NDVI derivatives of rice and the other studied herbaceous crops, and of the NDVI integrals of vineyard and the other studied woody crops. The resulting maps and tables provide valuable geospatial information for every parcel over time with several applications in cropland management, irrigation scheduling, and ecosystem modeling.

환경소음에 의한 피해의 경제적 가치 추정:군사격장 주변 토지 가격 분석

This study estimates the economic value of the damage caused by the noise by analyzing land prices in the area around a military live-fire complex (LFC). To do this, we create a noise map based on the noise level measured in the LFC and surrounding area, and combine it with the data of 10 years of assessed value and characteristics for land in the surrounding area. Using the panel data, the effect of the noise from the LFC on land prices of the surrounding area is statistically analyzed. The results show that the level of land price decreases by about 4250 KRW/m² ~ 5485 KRW/m² as the noise level increases by 10 dB(C), and that the growth of land price varies depending on the noise level of the area. The results will be able to be used to estimate the economic value of the noise damage from the LFC for the entire surrounding area as well as for individual parcels.

Eulerian–Lagrangian spray atomization model coupled with interface capturing method for diesel injectors

Traditional Discrete Particle Methods (DPM) such as the Euler–Lagrange approaches for modeling atomization, even if widely used in technical literature, are not suitable in the near injector region. Indeed, the first step of atomization process is to separate the continuous liquid phase in a set of individual liquid parcels, the so-called primary break-up. Describing two-phase flow by DPM is to define a carrier phase and a discrete phase, hence they cannot be used for primary breakup. On the other hand, full scale simulations (direct simulation of the dynamic DNS, and interface capturing method ICM) are powerful numerical tools to study atomization, however, computational costs limit their application to academic cases for understanding and complementing partial experimental data. In an industrial environment, models that are computationally less demanding and still accurate enough are required to meet new challenges of fuel consumption and pollutant reduction. Application of DNS-ICM methods without fairly enough resolution to solve all length scales are currently used for industrial purposes. Nevertheless, effects of unresolved scales are generally cast aside. The Euler-Lagrange Spray Atomization model family (namely, ELSA, also called, Σ−Y or Ω−Y) developed by Vallet and Borghi pioneering work (Vallet and Borghi, 1999a), and (Vallet et al., 2001), at the contrary aims to model those unresolved scales. This approach is actually complementary to DNS-ICM method since the importance of the unresolved term depends directly on mesh resolution. For full interface resolution, the unclosed terms are negligible, except in the far-field spray when the unresolved terms become dominant. Depending on the complexity of the flow and the available computational resources, a Large Eddy Simulation (LES) formalism could be employed as modeling approach. This work focus on the two main terms that drive these different modeling approaches namely the sub-grid turbulent liquid flux and the unresolved interface. Thanks to the open source library OpenFoam® (Weller et al., 1998) this work is an attempt to review and to release an adapted modeling strategy depending on the available mesh resolution. For validation, these solvers are tested against realistic experimental data to see the overall effect of each model proposal. It was found that both showed good agreement with experiments, and particularly under Diesel Spray injection conditions, the sub-grid scales represent the major driving force, thus diffusing the interface rapidly at the exit of the injector.

Crop Classification in a Heterogeneous Arable Landscape Using Uncalibrated UAV Data

Land cover maps are indispensable for decision making, monitoring, and management in agricultural areas, but they are often only available after harvesting. To obtain a timely crop map of a small-scale arable landscape in the Swiss Plateau, we acquired uncalibrated, very high-resolution data, with a spatial resolution of 0.05 m and four spectral bands, using a consumer-grade camera on an unmanned aerial vehicle (UAV) in June 2015. We resampled the data to different spatial and spectral resolutions, and evaluated the method using textural features (first order statistics and mathematical morphology), a random forest classifier for best performance, as well as number and size of the structuring elements. Our main findings suggest the overall best performing data consisting of a spatial resolution of 0.5 m, three spectral bands (RGB—red, green, and blue), and five different sizes of the structuring elements. The overall accuracy (OA) for the full set of crop classes based on a pixel-based classification is 66.7%. In case of a merged set of crops, the OA increases by ~7% (74.0%). For an object-based classification based on individual field parcels, the OA increases by ~20% (OA of 86.3% for the full set of crop classes, and 94.6% for the merged set, respectively). We conclude the use of UAV to be most relevant at 0.5 m spatial resolution in heterogeneous arable landscapes when used for crop classification.

Increasing expansion of large-scale crop production onto deforested land in sub-Andean South America

A combination of high commodity crop prices, rising global food demand, and technological advances has transformed the scale of global crop production. Farming in South America is a prime example, where large-scale cash crops, such as soy, have transformed the land use dynamics at the forest frontier. We evaluate this transformation in sub-Andean South America by estimating crop and forest cover and detecting individual cropland field parcels using Landsat imagery in 5 year intervals over a 24 year period. From 1990 to 2014, cropland expansion onto deforested land was increasingly driven by large fields (>50 ha), whose contribution increased from 32% to 48% (+16% increase), while the contribution of smaller fields (<20 ha) declined from 36% to 26% (−10% decrease). This shift toward large-scale farming replacing cleared land across the region has important implications for food security and biodiversity conservation. Policy efforts will need to target different actors and transcend national borders in order to tackle the changing nature of South American deforestation.

How reliable is my historical land-use reconstruction? Assessing uncertainties in old cadastral maps

Old maps are a fundamental source for land-use reconstruction frequently used in biodiversity conservation and environmental management. In particular, cadastral maps as one type of old maps, depict both land tenure (discrete category) and land-use (continuous category); thus resulting in uncertainties in determination of individual parcels and their use. These uncertainties pose fundamental questions that are addressed in this paper: (i) to what extent land-use determined the delimitation of parcels?; (ii) how significant did the contrast between two land-use classes have to be to in order to delineate a new boundary? Agroforestry land-use classes were chosen as an example to demonstrate the approaches in the delimitation of parcels among different land-use combinations. We used Franciscan Cadastre, created in the mid-19th century under the Habsburg Monarchy (Central Europe), which depicts up to 10 agroforestry classes, to analyse factors that could influence delimitation of borders between patches (parcels) in old cadastral maps. The study area was located in the rural landscape of N Czechia, where approximately 10% of the agroforestry land area was used. We based our analysis on a detailed database of parcels and their land use type and property information. The novel approach to patch contrast indicator for old map analyses is introduced. The approach is based on statistical testing of the differences between parcel boundaries, separating similar/different owner, similar/different land-use and considering the length of the boundaries. Total number of identified parcels for all districts was 4108. Half of the boundaries length and 60% of boundaries count separated land of different owners. The rest of them separated land of one owner with different owner or with distinct parcels geometry. Our results indicate variable contrast between pairs of neighbouring land use categories. In particular, the contrast between pastures, wood-pastures and forests proved to be very low. Various factors, including land ownership, land-use, as well as landscape patch geometry and configuration were important to delineate a single parcel. We have concluded that these factors have important implications on inaccuracies and uncertainties of land use reconstructions based on old cadastral maps and used as historical baselines for current considerations on land change and environmental management.

Doublethink and scale mismatch polarize policies for an invasive tree.

Mismatches between invasive species management policies and ecological knowledge can lead to profound societal consequences. For this reason, natural resource agencies have adopted the scientifically-based density-impact invasive species curve to guide invasive species management. We use the density-impact model to evaluate how well management policies for a native invader (Juniperus virginiana) match scientific guidelines. Juniperus virginiana invasion is causing a sub-continental regime shift from grasslands to woodlands in central North America, and its impacts span collapses in endemic diversity, heightened wildfire risk, and crashes in grazing land profitability. We (1) use land cover data to identify the stage of Juniperus virginiana invasion for three ecoregions within Nebraska, USA, (2) determine the range of invasion stages at individual land parcel extents within each ecoregion based on the density-impact model, and (3) determine policy alignment and mismatches relative to the density-impact model in order to assess their potential to meet sustainability targets and avoid societal impacts as Juniperus virginiana abundance increases. We found that nearly all policies evidenced doublethink and policy-ecology mismatches, for instance, promoting spread of Juniperus virginiana regardless of invasion stage while simultaneously managing it as a native invader in the same ecoregion. Like other invasive species, theory and literature for this native invader indicate that the consequences of invasion are unlikely to be prevented if policies fail to prioritize management at incipient invasion stages. Theory suggests a more realistic approach would be to align policy with the stage of invasion at local and ecoregion management scales. There is a need for scientists, policy makers, and ecosystem managers to move past ideologies governing native versus non-native invader classification and toward a framework that accounts for the uniqueness of native species invasions, their anthropogenic drivers, and their impacts on ecosystem services.

Extracting Farmland Features from Lidar-Derived DEM for Improving Flood Plain Delineation

Flood plains, which are commonly distributed in flat river or lake basins, often contain large tracts of farmland. Therefore, flood plains require precise and detailed information on the role played by farmland in flood routing simulations, flood risk evaluation, and flood loss evaluation. In farmland, cultivated land parcels are not directly adjacent. The intervening non-cultivable land, which might include trails and ditches, can cover large areas. Currently, the area of non-cultivable land between cultivated land parcels is usually measured by artificial visual interpretation or by fieldwork. This study focused on the extraction of uncultivable trails, ditches, and cultivated field parcels within farmland on the basis of a Light Detection and Ranging-derived (LiDAR-derived) high-resolution gridded Digital Elevation Model (DEM). The proposed approach was applied to generate polygons of individual land parcels in a flood storage and detention area. The DEM was first smoothed and then subtracted. To remove small spots and to smooth the boundaries of the land parcels, inner and outer buffers were created to generalize the extracted polygons. Experiments proved that this approach is applicable in flood plain farmland and demonstrated that the chosen parameters were appropriate. This approach is more efficient than traditional surveying methods. For field parcel extraction, the accuracy achieved was 93.42%, using official statistics for comparison, and the Cohen’s kappa coefficient was 0.90, using a visual interpretation of an aerial image for comparison. The kappa coefficients were 0.87 and 0.77 for trail and ditch extraction, respectively.

PHYSICAL AND CHEMICAL PROPERTIES OF SOIL IN FRUIT GROWING AREA TOPOLA (SERBIA)

The aim of the investigation was to assess the level of soil fertility and repair measures in order to enhance the productivity of fruit production in a traditional fruit growing area. (Municipality of Topola, Serbia). The following tests were performed: mechanical composition, physical and chemical properties of soil, total adsorbed base cation, capacity of adsorbed base cation, degree of base saturation, different types of soil acidity, contents of carbon, humus, total nitrogen, easily accessible forms of P2O5 and K2O. Results obtained have shown that soils from all studied sites are of “heavy” mechanical texture with 75,40-84,90% of physical clay. High capacity of cation adsorption, low to medium hydrolytic acidity and high to almost complete saturation of adsorbed bases, has been measured. In compliance with previous analyses, it has been assessed that soils are neutral and of low acid chemical reaction, with low carbon and medium humus content and total nitrogen. Easily accessible content of P2O5 and K2O varies depending on the food quantity on individual parcels with low to medium accessibility to parcels with no fruit plantations. Based on the parameters analysed, the tested soils demand repair of mechanical properties, which will facilitate greater nutrient uptake.

GIS based optimal impervious surface map generation using various spatial data for urban nonpoint source management

Impervious surfaces are mainly artificial structures such as rooftops, roads, and parking lots that are covered by impenetrable materials. These surfaces are becoming the major causes of nonpoint source (NPS) pollution in urban areas. The rapid progress of urban development is increasing the total amount of impervious surfaces and NPS pollution. Therefore, many cities worldwide have adopted a stormwater utility fee (SUF) that generates funds needed to manage NPS pollution. The amount of SUF is estimated based on the impervious ratio, which is calculated by dividing the total impervious surface area by the net area of an individual land parcel. Hence, in order to identify the exact impervious ratio, large-scale impervious surface maps (ISMs) are necessary. This study proposes and assesses various methods for generating large-scale ISMs for urban areas by using existing GIS data. Bupyeong-gu, a district in the city of Incheon, South Korea, was selected as the study area. Spatial data that were freely offered by national/local governments in S. Korea were collected. First, three types of ISMs were generated by using the land-cover map, digital topographic map, and orthophotographs, to validate three methods that had been proposed conceptually by Korea Environment Corporation. Then, to generate an ISM of higher accuracy, an integration method using all data was proposed. Error matrices were made and Kappa statistics were calculated to evaluate the accuracy. Overlay analyses were performed to examine the distribution of misclassified areas. From the results, the integration method delivered the highest accuracy (Kappa statistic of 0.99) compared to the three methods that use a single type of spatial data. However, a longer production time and higher cost were limiting factors. Among the three methods using a single type of data, the land-cover map showed the highest accuracy with a Kappa statistic of 0.91. Thus, it was judged that the mapping method using the land-cover map is more appropriate than the others. In conclusion, it is desirable to apply the integration method when generating the ISM with the highest accuracy. However, if time and cost are constrained, it would be effective to primarily use the land-cover map.

JOHN MUIR MEETS WARREN BUFFETT: BIODIVERSITY MANAGEMENT AS A PORTFOLIO DECISION

ABSTRACT Moving from adversaries to partners, conservation organizations and corporations are jointly playing an important role in the preservation of biodiversity. For the conservation organizations, the focus is not solely on the ranking of preservation projects in terms of returns to biodiversity, but also the consideration of those projects in terms of risks to biodiversity. The conservation organizations consider both the rarity of the species or communities present and the likelihood that the species or community will survive on that site if it is preserved. The selection of the preservation projects is difficult due to the uncertainty of the biodiversity associated with individual parcels, the interaction between different preserves and the threats to preserved areas. Exercising an interdisciplinary approach that arises from the collaboration between conservation organizations and corporate partners, a variety of techniques from financial economics are used to examine decision making in the face of such uncertainty. The threats to biodiversity are analyzed and a measure of biodiversity that incorporates the preferences of the stakeholders is developed. Portfolio analysis and simulation are employed to demonstrate the potential usefulness of concepts such as diversification and stochastic dominance in conservation organizations’ choices of parcels for preservation. Keywords Risk Analysis, Biodiversity, Sustainable Development

Detection of cropland field parcels from Landsat imagery

A slowdown in global agricultural expansion, spurred by land limitations, improved technologies, and demand for specific crops has led to increased agricultural intensification. While agricultural expansion has been heavily scrutinized, less attention has been paid to changes within cropland systems. Here we present a method to detect individual cropland field parcels from temporal Landsat imagery to improve cropland estimates and better depict the scale of farming across South America. The methods consist of multi-spectral image edge extraction and multi-scale contrast limited adaptive histogram equalization (CLAHE) and adaptive thresholding using Landsat Surface Reflectance Climate Data Record (CDR) products. We tested our methods across a South American region with approximately 82% of the 2000/2001 total cropland area, using a Landsat time series composite with a January 1, 2000 to August 1, 2001 timeframe. A thematic accuracy assessment revealed an overall cropland f-score of 91%, while an object-based assessment of 5480 fields showed low geometric errors. The results illustrate that Landsat time series can be used to accurately estimate cropland in South America, and the low geometric errors of the per-parcel estimates highlight the applicability of the proposed methods over a large area. Our approach offers a new technique of analyzing agricultural changes across a broad geographic scale. By using multi-temporal Landsat imagery with a semi-automatic field extraction approach, we can monitor within-agricultural changes at a high degree of accuracy, and advance our understanding of regional agricultural expansion and intensification dynamics across South America.

Geometrical data validation in 3D digital cadastre − A case study for Victoria, Australia

Data ambiguity and invalidity can cause significant expensive issues in the cadastral domain (e.g. legal disputes). An automated data validation can significantly help to reduce the potential issues. Quality assurance has been comprehensively investigated in various domains, however, the validation of 3D cadastral data is still in its early development. The availability of various regular and irregular shapes for 3D cadastral objects and modern building designs has resulted in a critical need for developing validation rules to ensure data validity and quality.The land registry in Victoria, Australia, is investigating the technical requirements for implementing a 3D digital cadastre. The study of 3D cadastral data validation requirements has been part of this ongoing investigation. This study is being undertaken in three main phases including 1) developing geometrical validation rules, 2) developing non-geometrical validation rules, 3) implementing an online service to validate 3D cadastral data.This paper aims to discuss the initial outcomes of the first phase of the aforementioned study which has focused on developing geometrical validation rules for 3D cadastral objects. The paper reviews the development of four geometrical validation rules which have been formalised using mathematical expressions to check the individual 3D parcels and their relationships with adjoining or neighbouring parcels. The first validation rule checks the compatibility of the cancelled parcel against the created parcels. The second rule deals with parcel collision detection which is required for flagging unacceptable intersection of 3D objects. The third rule ensures the faces forming a 3D parcel are flat. The fourth validation rule assures 3D objects are watertight. The paper concludes with a discussion around the impacts of the proposed validation checks on the subdivision process and future research for the Victorian 3D digital cadastre.

Origins of Moist Air in Global Lagrangian Simulations of the Madden–Julian Oscillation

Many recent studies have characterized the Madden–Julian Oscillation (MJO) as a moisture mode, suggesting that its amplification and eastward propagation result from processes that build up moisture to the east of the MJO’s convective center, including frictionally driven boundary layer convergence, surface fluxes, and shallow convection. Discussions of MJO moistening under this theory often implicitly assume an Eulerian framework; i.e., that local increases in moisture result from physical processes acting in the same location as the moistening is observed. In this study, the authors examine MJO moistening in a Lagrangian framework using a model that simulates atmospheric circulations by predicting the motions of individual air parcels. Back trajectories are presented for parcels in moist convecting regions of the MJO, and the effects of different physical processes on their moisture and moist static energy budgets are quantified. The Lagrangian MJO simulations suggest that much of the low-level moist air in heavily precipitating regions of the MJO arrives via the mid troposphere, coming from nearby equatorial regions, where it has been moistened largely by convective processes. Consequently, a thorough understanding of MJO moistening requires knowledge of the origin of the moist air and information about remote moisture sources.

A Database of Weekly Sea Ice Parcel Tracks Derived from Lagrangian Motion Data with Ancillary Data Products

Arctic sea ice has been on the decline over the past several decades, and multi-year sea ice has decreased significantly in its areal share of the overall sea ice cover. Changes in several key variables such as radiative balances, albedo, ice surface temperature, and ice thickness have driven much of the decline, but the motion of sea ice makes studying the effects of these variables on individual parcels difficult. Previous studies have observed changes in the means of these variables and their impacts on sea ice concentration, but an accessible database of Lagrangian tracked data is not yet available for study. In order to address this, a database has been developed at the University of Colorado Boulder that performs Lagrangian tracking on individual sea ice parcels and saves coincident ancillary thermodynamic and dynamic variables for each parcel on a weekly timescale.

Analyzing Simulated Convective Bursts in Two Atlantic Hurricanes. Part I: Burst Formation and Development

AbstractUnderstanding the structure and evolution of the tropical cyclone (TC) inner core remains an elusive challenge in tropical meteorology, especially the role of transient asymmetric features such as localized strong updrafts known as convective bursts (CBs). This study investigates the formation of CBs and their role in TC structure and evolution using high-resolution simulations of two Atlantic hurricanes (Dean in 2007 and Bill in 2009) with the Weather Research and Forecasting (WRF) Model.Several different aspects of the dynamics and thermodynamics of the TC inner-core region are investigated with respect to their influence on TC convective burst development. Composites with CBs show stronger radial inflow in the lowest 2 km, and stronger radial outflow from the eye to the eyewall around z = 2–4 km, than composites without CBs. Asymmetric vorticity associated with eyewall mesovortices appears to be a major factor in some of the radial flow anomalies that lead to CB development. The anomalous outflow from these mesovortices, along with outflow from supergradient parcels above the boundary layer, favors low-level convergence and also appears to mix high-θe air from the eye into the eyewall. Analyses of individual CBs and parcel trajectories show that parcels are pulled into the eye and briefly mix with the eye air. The parcels then rapidly move outward into the eyewall, and quickly ascend in CBs, in some cases with vertical velocities of over 20 m s−1. These results support the importance of horizontal asymmetries in forcing extreme asymmetric vertical velocity in tropical cyclones.

Género y privatización de la tierra. Dominio pleno y derecho del tanto en Atenco, Estado de México

Las políticas neoliberales han generado pobreza, migración e individualización de la propiedad agraria. El objetivo de este artículo es analizar el proceso de venta de tierras en cuatro de los seis ejidos que conforman al municipio de Atenco, Estado de México, poniendo particular énfasis en la adopción de dominio pleno y en el ejercicio del derecho del tanto por parte de las mujeres. La originalidad del artículo reside no solo en analizar la privatización de la tierra desde el enfoque de género, sino también en hacerlo en un municipio conocido históricamente por la defensa del territorio. Los datos fueron obtenidos a través de tres métodos: análisis de documentos ejidales, observación participante, y entrevistas grupales e individuales. Se identificaron dos patrones en la adopción del dominio pleno y en el ejercicio del derecho del tanto. En el primero, las transacciones se realizaron de manera individual (parcela por parcela), mientras que en el segundo las ventas fueron grupales. En ambos casos, las autoridades no protegieron los derechos de las mujeres y ellas tampoco los hicieron valer debido a su falta de información sobre cómo defender el patrimonio familiar.

The Influence of Multiple Ownership Interests and Decision-Making Networks on the Management of Family Forest Lands: Evidence from the United States

A national assessment of how the number of parcel owners influence family forest land management and use decisions in the US was conducted using a subset of the US Forest Service’s National Woodland Owner Survey Dataset. Seventy-two percent of single parcel family forest land ownership respondents of at least 4.05 ha had multiple owners. The extent to which past land management practices and future intentions for the land are influenced by the number of owners of an individual parcel was evaluated. We also examined how landowner decision-making networks are related to past practices and future intentions. Contrary to previous findings, our research suggests that having more than one owner does not necessarily reduce the likelihood that a variety of different forest management activities, including commercial timber harvesting or wildlife habitat improvement, will occur. Moreover, we found that one-owner forested parcels are less likely to have experienced activities like harvesting, invasive plant removal, fire hazard reduction, wildlife habitat improvement, and cost-share program participation than parcels with two or more than two owners. We also found that family member involvement in landowner decision-making has a minimal effect on past and planned land management actions, while the involvement of a forester or land manager in decision-making increases the likelihood many land management actions have been or will be undertaken.