For animals with spatially complex behaviours at relatively small scales, the resolution of a global positioning system (GPS) receiver location is often below the resolution needed to correctly map animals’ spatial behaviour. Natural conditions such as canopy cover, canyons or clouds can further degrade GPS receiver reception. Here we present a detailed, high-resolution map of a 4.6 ha Neotropical river island and a 8.3 ha mainland plot with the location of every tree >5 cm DBH and all structures on the forest floor, which are relevant to our study species, the territorial frog Allobates femoralis (Dendrobatidae). The map was derived using distance- and compass-based survey techniques, rooted on dGPS reference points, and incorporates altitudinal information based on a LiDAR survey of the area.
Summary
Materials flow analysis (MFA) generates highly aggregated indicators for the material “scale” of national economies. Similarly, transport statistics operate with indicators for the scale of freight transport activity. This article presents a model that seeks to predict the scale of freight transport from material flows. In the first part, the model MEFASPACE is developed conceptually and formally, as a linear and static (“mechanistic”) model linking biophysical variables by defined causalities (“white box”). The key prediction is that transport volume (TV in metric tons) relates to direct material input (DMI) by a reloading factor, which, for thermodynamic reasons, varies very little. Transport work (TW in metric ton kilometers), the most common indicator for transport activity, depends on TV and distance per haul. In a second part, we probe this model with transport statistics from European countries for the past four decades. Whereas for road and rail transport statistical indicators exist for many countries and years and comply with our model's theoretical definitions, they are either lacking or not complying well for other modes. The results were encouraging, nevertheless. In the past four decades, DMI corresponded very closely to TV as predicted, with a reloading factor that is in the expected range (1–3) and fairly stable across countries and time. At the same time, distances per haul showed a much more dynamic pattern, with quite a bit of variation between countries and a clear tendency to increase over time. Thus, MFA opens a new path for projections and scenario building for freight transport, but needs to be coupled to knowledge from other fields to generate a full picture of transport distances and, finally, environmental pressure.
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