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Volume XV |

The Assessment of Artificial Water Surfaces Regeneration in Stachinez Swamps Protected Area by Using Remote Sensing and In–situ Data

Abstract: The Satchinez Swamps, a remnant of the swamps once specific for Banat Plain, is an ornithological reserve since 1942 and the habitat of many protected bird species. Draining works conducted in the seventies affected the reserve by decreasing the water surface area. Thirty-five years later, hydro-technical works aiming to restore the former aquatic surfaces within the buffer zone were conducted. Thus, in 2005 a water delivery canal from the discharge canal of Satchinez reservoir towards Balta Mare was built. The objective of this study is to assess the efficiency of the hydrological works carried out in 2005 by using temporal analysis of some normalized difference indexes derived from satellite images, in relation to precipitation data (recorded at Timisoara meteorological station) as an indicator for wetland restoration. We used geospatial data from different time periods: historical maps (1953, 1962 and 1984), orthophotos (1963, 1970, 2005 and 2012), oblique airphotos (2004) and 38 Landsat satellite scenes (1984-2015), two images per year, for the dry season respectively for the rainy season. We noticed a slight increase of the Normalized Difference Vegetation Index (NDVI) in Balta Mare and on the relict watercourse of Sicsău stream, which shows the expansion of reed and suggests an increase in soil moisture. During the dry season, for the period before the restoration works (1984 – 2004) there is a strong, very significant correlation between Normalized Difference Water Index (NDWI) and precipitations (r =0.7008, p = 0.0011). After 2005, this correlation no longer occurs (r = -0.1083, p <0.05), which demonstrates that precipitations are not the main water supply for Balta Mare anymore. For the 1984 – 2015 period, during rainy months the Modified Normalized Difference Water Index (MNDWI) indicate the presence of water in Balta Mare, but during the dry months, it demonstrates the lack of water which underlines the temporary character of this pond and confirms the field observations. We conclude that the restoration did not succeed in the rebuilding of the former water surfaces of Balta Mare, but has an effect in increasing the underground water level in this area followed by reed extension.

Volume XI |

Trends in land cover change in abandoned mountain pastures. A case study: Măgura Marga Massif (the Southern Carpathians)

Abstract: Grazing was the main activity of the inhabitants of the region, so that on an area of only 750 hectares, 16 sheepfolds existed simultaneously. In the last 20 years, mountain pastures were gradually abandoned a fact which led to some changes in land cover, mainly close to timberline. The aim of this paper is to identify general trend of land cover change using change – detection methods based on Landsat TM imagery for 1988 – 2011 time interval. Detailed analysis based on field research and high resolution air photos was also made for the areas with highest land cover changes. The analysis of the historical maps allowed a better understanding of the land cover transformations in the last 70 years. The results showed that the general trend in pastures area for the last 23 years is the biomass gain. Even if this phenomenon has a low and medium magnitude, it is a dominant one, appearing on more than 88% of the pastures area. Moderate intensity changes are explained due to the relatively short time interval since pastures were abandoned. Major changes occurred in some areas: on the southern slopes, because of the specific topoclimate, in areas where the anthropogenic timberline was lowered at very low altitudes and in the areas near the spruce timberline. There are also areas where there are no obvious changes of the timberline. These occur more frequently on the northern and western slopes, near the beech forest timberline. In the study area, the timberline is still anthropogenic, but if the current trend of forest regeneration continues, the timberline will change to a climatic one.