Assessing regional geodiversity: the Iberian Peninsula

Abstract

Geodiversity is a landscape characteristic related to the heterogeneity of the physical properties of the earth surface. In this work, we quantify and compare geodiversity in several geodynamic zones of the Iberian Peninsula. For this purpose, we have developed a geographic information system (GIS) procedure to carry out a regional terrain classification based on geodiversity factors. A classification process helped to produce a morphometric map (10 classes), a morphoclimatic map (five classes) and a geological map (15 classes). These three maps were combined using an overlay operation (union) to obtain the final terrain classification (419 classes), which was then applied to calculate diversity landscape indices. The latter were calculated using common landscape diversity indices (Patch Richness Density, Shannon's Diversity Index, Shannon's Evenness Index, Simpson's Diversity Index and Simpson's Evenness Index), provided by FRAGSTATS free software. These indices were calculated for the whole landscape of the main Iberian geological regions, thus revealing a close relationship between some index values and the geological and geomorphological characteristics. The highest diversity values are associated with Alpine collisional orogens and reactivated chains of the Precambrian-Palaeozoic massif. Intraplate orogen with sedimentary cover, characterized by extensive planation surfaces, have lower values. Mesozoic areas with no significant tectonic deformation and Cenozoic basins are characterized by the lowest diversity values. Amongst the latter, the major diversity is associated with the most dissected basins, which also present higher morphoclimatic variety. Though depending on the chosen scale and the landscape classification criteria, these indices provide an objective assessment of the regional geodiversity of Iberia.

Landform values for rural sustainability: Recognition and assessment in a Spanish–Portuguese border region case study

“…It belongs to the inland border between southern Galicia (Spain) and the North of Portugal, named as raia seca (dry border) in contrast with the borderline set by the fluvial watercourse of the lower Miño River. The highest geodiversity values in this IP sector are closely related to their interests for understanding the origin and evolution of the oldest Iberian Massif terrains (Benito-Calvo et al, 2009 Thomé (1978) pointed out that the Larouco summits would be affected by glacial processes during the Pleistocene, with two (independent) layers of permanent ice above 1,250 m. In the Portuguese area, Coudé-Gaussen et al (1983) stated the importance of the snow, without ice formation, and Vieira et al (2015) mentioned that the main processes would have been periglacial. The absolute dating attests to the presence of small glaciers in the nearby Ger�s-Xurés Mountains (Vidal-Romaní et al, 2015), with an age of 300 kyr BP for the stage of maximum glacial advance during the Pleistocene.…”

Topography-based flow-directional roughness: potential and challenges

“…For example, in the context of geomorphologic interpretation, the maps of differences and relative differences between R flow and R iso represent useful geomorphometric indicators. In particular, these indicators are capable of discriminating between anisotropic surface textures elongated and orthogonal to the direction of the slope gradient; moreover, the spatial patterns of areas of positive and negative differences furnish interesting information on the spatial organization of the morphology, useful from the interpretative perspective as well as in the context of geodiversity considerations (Benito-Calvo et al, 2009;McGarigal et al, 2009;Melelli, 2014). Moreover, the areas with lower R flow than R iso often include areas of preferential flow; alternatively, areas with higher R flow than R iso exhibit features that act as an obstacle to flow.…”

“…The morphological information extracted by the flow-directional roughness, also with its comparison to isotropic roughness, can provide meaningful information from geomorphologic and geo-structural perspectives and for further quantitative usage. Flow-directionalbased indices could be quantitatively exploited in many geomodeling and geo-engineering contexts, such as geomorphological and lithological automatic mapping (e.g., Cracknell and Reading, 2014), landslide susceptibility models and geodiversity evaluations (Benito-Calvo et al, 2009;Booth et al, 2009). Flow-directional roughness is a better candidate than isotropic roughness to be used as a proxy of impedance to flow; this is particularly true in areas characterized by strong anisotropy in surface morphology (Trevisani and Rocca, 2015), with elongated morphological features aligned or orthogonal to the direction of flow.…”

The importance of mountain geomorphosites for environmental education: examples from the Italian Dolomites and the Swiss Alps

“…They are, therefore, recognized as natural areas with a very high geodiversity, especially the Alpine collisional orogens (Benito-Calvo et al 2009) in contrast with Tertiary foreland sedimentary basins. This high landform diversity (Thomas 2012, Zwolişski andStachoviak 2012), often over very short distances, provides open-air laboratories where processes and landscape evolution can be studied and transmitted to a non-specialized public.…”