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Chlorophyll is the basic pigment for photosynthesis. Vegetation senescence can be accelerated if this process is hampered by external factors. Remote sensing tools contribute to vegetation stress detection. Previous studies correlated chlorophyll values with vegetation indices and red-edge shoulder position. This paper explored the applicability of multi- and hyperspectral satellite images and in-situ spectrometry data for identifying healthy and stressed vegetation in four parks within Bucharest, the capital city of Romania. It integrated data from Sentinel-2 MSI, EO-1 Hyperion and STS-VIS spectrometer from Ocean Optics. Overview of vegetation health is delivered by spaceborne sensors, using vegetation index values. MTVI indicates that vegetation in Unirii Park is the most affected, whilst Herăstrău Park and Tei Park are better managed. Furthermore, red-edge position analysis using leaf reflectance of three species (ash tree, linden tree, pine) confirmed the findings from satellite images. All analysed species Unirii Park and Păcii Park showed signs of high stress, resulting in a red shift of the red-edge position. Ash tree in Herăstrău Park is rather healthy. All species in Tei Park seemed to record a normal senescence rhythm. [ABSTRACT FROM AUTHOR]

One of the key elements in monitoring forest changes is Remote Sensing. With the increase of public available satellite images, like Landsat and Sentinel 1 and 2 (DeVries et al. 2015), the accuracy of forest disturbance mapping in space and time has also increased significantly. Even though the number of available satellite images has increased, tracking changes in space and time still has to deal with cloud cover. Obtaining images for at least two distinct points in time, with very similar environmental conditions is not always easy to achieve (Rodriguez-Galiano and Chica-Olmo 2012). In this paper we assessed the accuracy of different machine learning algorithms for mapping forest disturbance for small time intervals and not very similar environmental conditions (Pelletier et al. 2016). We considered the forest disturbance as full canopy removal without a special emphasize on the natural or anthropogenic processes (Griffiths et al. 2014). Hence, any significant change in canopy recorded between two or more time intervals was considered disturbance. Our test site is Făgăraș Mountains, located in the central part of Romania. For this site we used the entire archive for Landsat and Sentinel-2 imagery. Because of the lack of available images for each year, the time intervals are not equal throughout the entire time period. To compensate for the uneven time intervals and better understand the space-time patterns in forest disturbance, we gradually increased the time interval by 1, assessed the forest disturbance pattern for the new time interval and continue until we reached one big time interval, delimited by the first and the last available images. [ABSTRACT FROM AUTHOR]

Many large marginal water bodies on Earth, partially disconnected from the open ocean by shallow sills, have been land-locked in ancient times (e.g., the Mediterranean Sea; the Black Sea, the modern Baltic Sea region). Disconnected from the global ocean, these "sea-lakes" would expand or contract, controlled by their hydrological budget. Spectacular marine flooding events would occur when basins with negative water budgets would reconnect with the ocean while lake burst floods would characterize the reconnection of the basins with positive water budgets. Key examples of marine floods are the Zanclean flood in the Mediterranean and the Black Sea Deluge, also known as Noah's flood, while the archetypes lake burst floods are best exemplified by the erosional features of the English Channel, lake Bonneville and Lake Missoula floods. Here, we show that Paratethys, a Miocene mega-lake from central Eurasia has generated at least two mega-floods into the Mediterranean during Messinian times via a river system, which we call Styx. The late Miocene history of Paratethys is marked by a succession of lake level changes, and paleogeographic estimates show that the maximum water level (~50 m above global sea level) was reached during the early Messinian (lower Maeotian in regional stratigraphic terms). This was followed by a sudden lowering of Paratethys water level, the Intra Maeotian Event (IME), after which Mediterranean mollusc species entered Paratethys during the upper Maeotian. After a major short-lived marine influx termed the Pontian Flood, Paratethys water level dropped again at the regional Pontian-Kimmerian transition (5.6 Ma), an event that was linked to the low-stand of the Mediterranean during the Messinian Salinity Crisis. Here we investigate the cause for these two sudden drops of Paratethys water level. We hypothesize that they are related to collapses of the sills separating it from the Mediterranean due to erosion from a mega-river. We develop two paleogeographic Digital Elevation Models (DEM) to calculate the gigantic volume of water that would have flooded into the Mediterranean and we estimate these discharges are the largest lake-burst floods in the record. Our proposed lake burst scenarios are providing an explanation for a long list of previously unexplained anomalies observed in the Paratethys-Mediterranean region. This work also documents the diverse expressions of lake burst floods cataclysms in the sedimentary record and details a particular mechanism for the birth of sea straits in the aftermath of large water discharge events. [ABSTRACT FROM AUTHOR]