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Cyperus rotundus (purple nutsedge) is considered one of the most noxious weeds affecting agricultural areas worldwide. With its fast growth rate, it competes with annual crops for water, minerals, light and space. It excretes allelopathic materials that impede crop development. Controlling this weed is difficult and is done mostly by manual weeding, cultivation and herbicides, with limited effectiveness. A method was developed for the control of C. rotundus. A machine penetrates the soil and rearranges it, so that the tubers are lifted to the upper soil layer, where they are left exposed to the hot summer climate, dehydrate and die. The method was tested in seven field experiments on various soil types. Two months after the experimental plots were irrigated, 70-100% weed control was observed. The machine's speed (at 1.2 or 1.8 km h−1) and the number of treatments (one, or two treatments a month apart) did not influence the level of weed control. The method has a very high potential to replace manual weeding and application of herbicides. Further work will test whether the treatment has a long-term effect or should be repeated every season. [ABSTRACT FROM AUTHOR]

ABSTRACT Macrophytes are a key biological component in many fluvial ecosystems. In altered streams, they can become highly dominant features, covering extensive parts of the channel with cascading effects on stream conditions and biological composition. The aim of this study is to examine the possibility of using information collected by aerial digital photography-spectral analysis (ADP-SA) as an alternative, cost-effective methodology to the commonly used spectral procedure at a large (section) scale, and to the ground level visual survey (gridded frame) at a smaller (organism) scale. Cladophora glomerata and Nasturtium officinale, were selected as the targeted macrophyte species and classified at the same time (species relative cover) by using the three methodologies. Our findings show that the ADP-SA methodology was able to detect species and relative cover in similar accuracy (≤10% differences) at the two spatial scales. ADP-SA had a better spatial resolution than both the hyperspectral and the visual methodology (4 cm vs. 1 m and 10 cm, respectively) and was capable to differentiate submerged from emergent plants. However, on a smaller scale, ground level work is suitable and essential for detecting rarer species and is not hindered by weather, canopy cover or multi-layered plant composition. ADP-SA can therefore add a cost-effective and nonsubjective practice to the existing tool kit of macrophyte surveys, particularly in small streams, which require high spatial resolution. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper systematically derives and analyses the generic phenomenon of space-invariant predictability of spatio-temporal observation fields using past multitemporal observations. We focus on thermal infrared remote sensing as a non-trivial example illustrating the predictability concept. The phenomenon and the systematic analysis thereof are experimentally demonstrated to be productive for developing effective automated anomaly detection and classification methods operating under the assumption of dynamic environment and sensor response. Using a simple preliminary experiment involving uncalibrated tower-based high-resolution thermal infrared surveillance, we test the conceptual validity of the space-invariant multitemporal prediction and exemplify its potential applications. In addition, we use a MODIS thermal image sequence and the task of hot anomaly detection to demonstrate the applicability of the approach for monitoring the status of large territories from space-borne platforms. [ABSTRACT FROM AUTHOR]

Temporal changes in the stabilization process along the coastal dunes of Israel were assessed using a series of 23 aerial photographs taken over the period 1944–1999. The stabilization rate was then quantified using a specially developed method for the calculation of sand dune movement and by the calibration of the gray-scale images into vegetation cover maps. An episodic reactivation of the dunes during the 1970s was identified and examined with respect to various physical and human factors. The Mediterranean climate along the coast of Israel and the low wind energy are favorable for the stabilization of sand dunes in the absence of human activity. It was shown that military maneuvers and recreational traffic (pedestrians and off-road vehicles) increased fragmentation but did not lead to the reactivation of the dunes. Based on archival records and interviews with officials who have worked in the area over the past 25 years, it was concluded that the apparent changes in the stabilization process should be attributed to changes in the grazing and vegetation cutting practices of Bedouin farmers along the coast of Israel between the late 1960s and the late 1970s, concomitant with the changing policies of successive Israeli governments. [Copyright &y& Elsevier]

A synthetic data spectral cube that represents at-sensor radiance data of AVIRIS was used to examine the accuracy of several methods to recover absolute surface reflectance data of terrestrial targets. Soil and vegetation targets, selected to represent the images of ground variation and their spectra, were retrieved using HATCH, Empirical Line (EL) and their hybrids methods. After a synthetic radiance data cube was generated, reflectance recovery was carried out and compared with the true (input) reflectance information. It was found that even under controlled and ideal conditions, the spectral recovery using HATCH code provided differences of up to 40%. The EL methods, using the two end-members that represent the scene reduced this difference to about 4%, and in some cases, even to 0.1% It was found that selecting the calibration targets over low water vapor content improved the results. Applying EL on radiance data provided a severe difference of more than 200% in areas located outside the calibration target water vapor zone. Only over similar water vapor zones were the EL methods found to reasonably recover the surface reflectance. Examining the spectral variability in the calibration targets showed that using of spectral features targets with relative spectral similarity is almost as effective as using spectrally featureless targets for the EL process. Applying EL, using external spectral information of possible known targets, revealed a relatively high difference, as compared to the true reflectance data. However, thematic analysis using a SAM classifier proved that even under non-ideal conditions, the EL correction can yield a reasonable spatial mapping capability relative to those obtained under real reflectance domains. It was concluded that EL must be run on reflectance data (generated from absolute based method) over low water vapor zones to provide the most precise reflectance information. Also, it was found that it is not mandatory to select calibration targets that are totally featureless or characterized by low or high albedo response. [Copyright &y& Elsevier]