A region and contour based technique for automatic detection of tomato roots in minirhizotron images

Erz G, Veste M, Anlauf H, Breckle S-W, Posch S. A region and contour based technique for automatic detection of tomato roots in minirhizotron images. Journal of Applied Botany and Food Quality -Angewandte Botanik. 2005;79(2):83-88.The use of minirhizotrons is a common tool to investigate fine roots turn-over in a variety of ecosystems. Manual analysis of the resulting images is very time consuming, however. An improved approach for automatic root detection combining region and contour based techniques was developed. The first step is aimed at detecting easily recognizable parts of the root (optimally at least one part of each root), which will be called a R-SEED subsequently in this paper. In a second phase each R-SEED is expanded with a more sophisticated algorithm to find the boundaries of the complete root. 14 time series with 3 to 8 images of tomato fine roots were digitized, processed and used to validate the approach. As the R-SEED detection influences the overall performance strongly the approach benefits from the improved algorithm. In four out of five images from one time series examined in detail the root area detected is nearly correct with an relative error between -8.8% and +7.3%. In one image the detection fails substantially due to decomposed roots. In general, the root area detected is systematically lower than the area marked manually

La structure iconographique d'un art rupestre est-elle une clef pour son interprétation?

Develops a method for discriminating between different social contexts in which rock art is created and applies the method to ethnographic and archaeological case studies

Weather and Prey Predict Mammals’ Visitation to Water

<div><p>Throughout many arid lands of Africa, Australia and the United States, wildlife agencies provide water year-round for increasing game populations and enhancing biodiversity, despite concerns that water provisioning may favor species more dependent on water, increase predation, and reduce biodiversity. In part, understanding the effects of water provisioning requires identifying why and when animals visit water. Employing this information, by matching water provisioning with use by target species, could assist wildlife management objectives while mitigating unintended consequences of year-round watering regimes. Therefore, we examined if weather variables (maximum temperature, relative humidity [RH], vapor pressure deficit [VPD], long and short-term precipitation) and predator-prey relationships (i.e., prey presence) predicted water visitation by 9 mammals. We modeled visitation as recorded by trail cameras at Sevilleta National Wildlife Refuge, New Mexico, USA (June 2009 to September 2014) using generalized linear modeling. For 3 native ungulates, elk (<i>Cervus Canadensis</i>), mule deer (<i>Odocoileus hemionus</i>), and pronghorn (<i>Antilocapra americana</i>), less long-term precipitation and higher maximum temperatures increased visitation, including RH for mule deer. Less long-term precipitation and higher VPD increased oryx (<i>Oryx gazella</i>) and desert cottontail rabbits (<i>Sylvilagus audubonii</i>) visitation. Long-term precipitation, with RH or VPD, predicted visitation for black-tailed jackrabbits (<i>Lepus californicus</i>). Standardized model coefficients demonstrated that the amount of long-term precipitation influenced herbivore visitation most. Weather (especially maximum temperature) and prey (cottontails and jackrabbits) predicted bobcat (<i>Lynx rufus</i>) visitation. Mule deer visitation had the largest influence on coyote (<i>Canis latrans</i>) visitation. Puma (<i>Puma concolor</i>) visitation was solely predicted by prey visitation (elk, mule deer, oryx). Most ungulate visitation peaked during May and June. Coyote, elk and puma visitation was relatively consistent throughout the year. Within the diel-period, activity patterns for predators corresponded with prey. Year-round water management may favor species with consistent use throughout the year, and facilitate predation. Providing water only during periods of high use by target species may moderate unwanted biological costs.</p></div

Differences in the timing of reproduction between urban and forest European blackbirds (Turdus merula): result of phenotypic flexibility or genetic differences?

Species which have settled in urban environments are exposed to different conditions from their wild conspecifics. A previous comparative study of an urban and a forest-living European blackbird population had revealed a three weeks earlier onset of gonadal growth in urban individuals. These physiological adjustments are either the result of genetic differences that have evolved during the urbanization process, or of phenotypic flexibility resulting from the bird's exposure to the different environmental conditions of town or forest. To identify which of these two mechanisms causes the differences in reproductive timing, hand-reared birds originating from the urban and the forest populations were kept in identical conditions. The substantial differences in the timing of reproduction between urban and forest birds known from the field did not persist under laboratory conditions, indicating that temporal differences in reproductive timing between these two populations are mainly a result of phenotypic flexibility. Nevertheless, urban males initiated plasma luteinizing hormone (LH) secretion and testicular development earlier than forest males in their first reproductive season. Moreover, plasma LH concentration and follicle size declined earlier in urban females than in forest females, suggesting that genetic differences are also involved and might contribute to the variations in the timing of reproduction in the wild