Global inventory of suitable, cultivable and available cropland under different scenarios and policies

Where land-use change and particularly the expansion of cropland could potentially take place in the future is a central research question to investigate emerging trade-offs between food security, climate protection and biodiversity conservation. We provide consistent global datasets of land potentially suitable, cultivable and available for agricultural use for historic and future time periods from 1980 until 2100 under RCP2.6 and RCP8.5, available at 30 arc-seconds spatial resolution and aggregated at country level. Based on the agricultural suitability of land for 23 globally important food, feed, fiber and bioenergy crops, and high resolution land cover data, our dataset indicates where cultivation is possible and how much land could potentially be used as cropland when biophysical constraints and different assumptions on land-use regulations are taken into account. By serving as an input for land-use models, the produced data could improve the comparability of the models and their output, and thereby contribute to a better understanding of potential land-use trade-offs

Synchronized flow and wide moving jams from balanced vehicular traffic

Recently we proposed an extension to the traffic model of Aw, Rascle and Greenberg. The extended traffic model can be written as a hyperbolic system of balance laws and numerically reproduces the reverse $\lambda$ shape of the fundamental diagram of traffic flow. In the current work we analyze the steady state solutions of the new model and their stability properties. In addition to the equilibrium flow curve the trivial steady state solutions form two additional branches in the flow-density diagram. We show that the characteristic structure excludes parts of these branches resulting in the reverse $\lambda$ shape of the flow-density relation. The upper branch is metastable against the formation of synchronized flow for intermediate densities and unstable for high densities, whereas the lower branch is unstable for intermediate densities and metastable for high densities. Moreover, the model can reproduce the typical speed of the downstream front of wide moving jams. It further reproduces a constant outflow from wide moving jams, which is far below the maximum free flow. Applying the model to simulate traffic flow at a bottleneck we observe a general pattern with wide moving jams traveling through the bottleneck.Comment: 10 pages, 12 figure

The nonrelativistic limit of the Magueijo-Smolin model of deformed special relativity

We study the nonrelativistic limit of the motion of a classical particle in a model of deformed special relativity and of the corresponding generalized Klein-Gordon and Dirac equations, and show that they reproduce nonrelativistic classical and quantum mechanics, respectively, although the rest mass of a particle no longer coincides with its inertial mass. This fact clarifies the meaning of the different definitions of velocity of a particle available in DSR literature. Moreover, the rest mass of particles and antiparticles differ, breaking the CPT invariance. This effect is close to observational limits and future experiments may give indications on its effective existence.Comment: 10 pages, plain TeX. Discussion of generalized Dirac equation and CPT violation adde

Use of remote sensing for hydrological parameterisation of Alpine catchments

International audiencePhysically-based water balance models require a realistic parameterisation of land surface characteristics of a catchment. Alpine areas are very complex with strong topographically-induced gradients of environmental conditions, which makes the hydrological parameterisation of Alpine catchments difficult. Within a few kilometres the water balance of a region (mountain peak or valley) can differ completely. Hence, remote sensing is invaluable for retrieving hydrologically relevant land surface parameters. The assimilation of the retrieved information into the water balance model PROMET is demonstrated for the Toce basin in Piemonte/Northern Italy. In addition to land use, albedos and leaf area indices were derived from LANDSAT-TM imagery. Runoff, modelled by a water balance approach, agreed well with observations without calibration of the hydrological model. Keywords: PROMET, fuzzy logic based land use classification, albedo, leaf area inde

Ecology of mallard ducklings on Lower Klamath National Wildlife Refuge, California

The ecology of female mallards (Anas platyrhynchos) and their broods was studied during 1988-90 on Lower Klamath National Wildlife Refuge, California. Survival of 127 radio-marked ducklings from 64 broods was 0.18 to 10 days of life, and 0.37 and 0.34 to fledging for 1988, 1989, and 1990, respectively. For the 3 years of the study, 49.2% of hens lost their entire brood; 81.2, 36.8, and 37.5% in 1988, 1989, and 1990, respectively. Ninety-three percent of mortality occurred on or before 10 days of life. No significant differences were detected in the proportion of radio-marked ducklings lost from early hatched or late hatched nests. A variety of predators consumed radio-marked ducklings; however, 49% of the cases of mortality were a result of an unknown predator. During 1989 and 1990, 3 radio-marked ducklings from 16 hens which appeared to lose their entire brood were fledged by other brood hens, and of 29 radio-marked ducklings that reached 44 days of life, 6 (20.7%) had joined other broods. Movements, home range, and habitat use were determined for 27 radio-marked broods. Relocation movements (>1000 m in 24 hrs) occurred in 12 of the 27 broods, primarily in the first week and after the fourth week of life. In 1989, significantly fewer radio-marked ducklings from broods hatching in permanent marshes survived to fledge compared to those originating in seasonal wetlands. Mean size of home ranges was 1.27 ± 0.47 km² and 0.62 ± 0.21 km² in 1989 and 1990, respectively. Most habitat selection by brood rearing hens occurred at the second order, (selection of home range area). Hens selected seasonally flooded wetlands with a cover component and avoided open or permanently flooded habitats. Estimated recruitment (females fledged/adult female in the spring population), proportional change in population size, and number of fledged young varied markedly during the 3 years of the study. Estimated recruitment was 0.31, 1.26, and 0.83 for 1988, 1989, and 1990, respectively. The estimated proportional change in population size ranged from 0.73 in 1988 to 1.29 and 1.04 during 1989 and 1990, respectively. Number of fledged young ranged from 915 in 1988 to 6,102 in 1989. Movements, habitat use, and survival of postbreeding radio-marked mallard hens were also determined. From mid-April to early August, 5,279 exposure days without the loss of a radio-marked hen were tallied. Of the 4 hens which emigrated from the study area, all were unsuccessful in rearing a brood. Unsuccessful hens moved to surveyed areas north of the study area significantly sooner than successful hens. Canals were the primary habitat utilized by postbreeding hens in 1988 while mixed seasonal and emergent permanent marsh were the most frequently used habitats in 1989 and 1990. Open seasonal and mixed seasonal marshes were the most frequently utilized habitats by incubating hens. Radio-marked hens moved a mean distance of 1,350 m from the nest to suspected feeding areas

Global cropland could be almost halved: Assessment of land saving potentials under different strategies and implications for agricultural markets

The pressure on land resources continuously increases not only with the rising demand for agricultural commodities, but also with the growing need for action on global challenges, such as biodiversity loss or climate change, where land plays a crucial role. Land saving as a strategy, where agricultural productivity is increased to allow a reduction of required cropland while sustaining production volumes and meeting demand, could address this trade-off. With our interdisciplinary model-based study, we globally assess regional potentials of land saving and analyze resulting effects on agricultural production, prices and trade. Thereby, different land saving strategies are investigated that (1) minimize required cropland (2) minimize spatial marginalization induced by land saving and (3) maximize the attainable profit. We find that current cropland requirements could be reduced between 37% and 48%, depending on the applied land saving strategy. The generally more efficient use of land would cause crop prices to fall in all regions, but also trigger an increase in global agricultural production of 2.8%. While largest land saving potentials occur in regions with high yield gaps, the impacts on prices and production are strongest in highly populated regions with already high pressure on land. Global crop prices and trade affect regional impacts of land saving on agricultural markets and can displace effects to spatially distant regions. Our results point out the importance of investigating the potentials and effects of land saving in the context of global markets within an integrative, global framework. The resulting land saving potentials can moreover reframe debates on global potentials for afforestation and carbon sequestration, as well as on how to reconcile agricultural production and biodiversity conservation and thus contribute to approaching central goals of the 21st century, addressed for example in the Sustainable Development Goals, the Paris Agreement or the post-2020 global biodiversity framework