Wetlands inventory is one of the goals of conservation plans on a national scale and a global scale. Inventories are needed for longterm monitoring or for identifying lost wetlands and those where restoration is feasible. In this article, we present an updated inventory of the saline wetlands of Southern Monegros, Spain. We depicted the evolution of these saline wetlands, locally named saladas with a unique long-term retrospective study based on aerial photographs from 1927. Their inventory has been accomplished through a map analysis based on a geographical information system using aerial photographs and orthophotographs, topographic maps, unpublished local studies and field surveys. Remaining vegetation, changes in soil moisture and colour, and geomorphology have been the key features in identifying the saladas. Their changes in number, size and shape have been driven by human pressure, the main modifier of landscape in the last 80 years. The information gathered will contribute to the awareness of stakeholders and decision makers for their conservation as natural resources. Moreover, our large retrospective approach is a consistent base from which to propose the inclusion of the saladas of Monegros in the Ramsar list of Wetlands of International Importance.

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Abstract:Inland saline wetlands are complex systems undergoing continuous changes in moisture and salinity and are especially vulnerable to human pressures. Remote sensing is helpful to identify vegetation change in semi-arid wetlands and to assess wetland degradation. Remote sensing-based monitoring requires identification of the spectral characteristics of soils and vegetation and their correspondence with the vegetation cover and soil conditions. We studied the spectral characteristics of soils and vegetation of saline wetlands in Monegros, NE Spain, through field and satellite images. Radiometric and complementary field measurements in two field surveys in 2007 and 2008 were collected in selected sites deemed as representative of different soil moisture, soil color, type of vegetation, and density. Despite the high local variability, we identified good relationships between field spectral data and Quickbird images. A methodology was established for mapping the fraction of vegetation cover in Monegros and other semi-arid areas. Estimating vegetation cover in arid wetlands is conditioned by the soil background and by the occurrence of dry and senescent vegetation accompanying the green component of perennial salt-tolerant plants. Normalized Difference Vegetation Index (NDVI) was appropriate to map the distribution of the vegetation cover if the green and yellow-green parts of the plants are considered.