Sierra Nevada National Park Research Articles

On the use of the digital elevation model to estimate the solar radiation in areas of complex topography

AbstractThe development of solar energy as a power source in the next few years requires reliable estimation of available solar energy resources. At local scales, topography is the most important factor in determining the distribution of solar radiation at the surface. Interpolation techniques are usually employed to estimate solar radiation where stations are not available, but their usefulness is limited where topography is an important source of variability. The use of satellite data and more recently of models based on techniques GIS, have contributed to solve this difficulty. In this work the usefulness of a digital elevation model (DEM) in providing topographic information for the estimation of solar radiation in areas of complex topography is analysed. Daily global radiation values were generated using the Solar Analyst software, which uses topographic information to generate radiation data. The generated data were compared with the experimental data obtained from 14 radiometric stations located within the Sierra Nevada Natural Park (southern Spain), an area of complex topography. Results show the usefulness of the topographic information derived from a DEM to estimate the solar radiation in areas of complex topography. Nevertheless, results depend on the DEM resolution and it is important that other factors, such as the albedo, should also be taken into account to obtain better estimates. Copyright © 2006 John Wiley & Sons, Ltd.

Effects of ungulates on epigeal arthropods in Sierra Nevada National Park (southeast Spain)

This paper examines the effect of ungulates on epigeal arthropod communities in two com- mon plant communities of the high mountains of the Sierra Nevada (southeast Spain). We have com- pared the abundance, biomass, diversity and specific composition of arthropod communities in grazed and ungrazed plots experimentally excluded from ungulates. In general, we found that arthropods were more abundant and diverse in grazed than in ungrazed plots. However, the effect of ungulates depended on the variable considered (diversity versus abundance versus biomass). Moreover, ungulates also af- fected species composition. This means that without affecting diversity, ungulates can still have a strong effect on arthropod communities by changing species composition. Also, the relationship between un- gulates and arthropods differed depending on the year of study and the sampling period. In conclusion, our study indicates that to extrapolate the results obtained for a group of insects, a habitat or a sampling period is not appropriate for the conservation of arthropod communities.

Are Mediterranean mountains Entisols weakly developed? The case of Orthents from Sierra Nevada (Southern Spain)

Two Orthents from Sierra Nevada National Park (Spain), classified as loamy-skeletal mesic Typic Xerorthent and loamy-skeletal frigid Lithic Cryorthent were studied. They were situated at 1460 and 2000 m, derived from micaschists and quartzites under Mediterranean mountain climate conditions with mesic and cryic temperature regimes and xeric moisture regime. These Orthents are weakly developed, as shown by their reduced thickness, their lack of diagnostics subsurface horizons, sandy loam textures, skeletal, and lithochromic colors. Quartz is present in significant amounts, particularly in the fine light sand fraction. Analysis of the quartz grains of the fine light sand by scanning electron microscope (SEM) and backscattered electron images (BSE) revealed the presence of significant physical and chemical alteration features such as fractures, corrosion gulfs, fields of etch pits and dissolution of intergranular surfaces. This process is confirmed by electron microprobe analysis (EMPA) since the edges of the quartz grains have a higher proportion of cations other than Si, compared to their centre. Further evidence indicates the authigenic nature of the process. Starting from quartz etching an assessment of soil weathering has been made ( W index from Marcelino et al. (1999). The alteration of the quartz, together with the development of a ultramicrofabric with several fabric units (investigated with SEM), and other characteristics (mineralogical, chemical, etc.) are considered indicative of some pedogenic evolution. These facts are especially interesting in the case of weakly developed Mediterranean mountain soils from Sierra Nevada, where processes of chemical weathering have traditionally not been considered very active.

Food habits of the wildcat (Felis silvestris) in a peculiar habitat: the Mediterranean high mountain

The feeding spectrum of the wildcat Felis silvestris Schreber, 1777 was studied in two sites with different ecological characteristics, both situated in the same Mediterranean environment in the high mountain of the Sierra Nevada National Park, south‐east Spain, where the rabbit Oryctolagus cuniculus is absent. Scat analysis (n=101 faeces; n=402 prey items) showed that the diet is based on rodents, fundamentally wood mouse Apodemus sylvaticus, Mediterranean pine vole Microtus duodecimcostatus and south‐western water vole Arvicola sapidus. Results showed strong differences between the two sites (χ2=74.04, d.f.=5, P<0.001), that is a predominance of voles in the mesic Chico river, whereas mice are predominant in the xeric Tejos ravine. Red‐legged partridge Alectoris rufa and carrion also played an important role, especially in biomass terms. The overall diet differed essentially from that of the Mediterranean region, which surrounds the study area, since in these areas rabbits constitute the primary prey. However, the diet of the mountain wildcats is similar to that in the Eurosiberian floral region, despite its distance from the Sierra Nevada. In conclusion, the Iberian wildcat seems to behave as a facultative specialist, since it prefers rabbits whenever they are available, but rodents constitute most of its diet if rabbits are scarce or absent.

A survey of the gastrointestinal nematodes of Spanish ibex (Capra pyrenaica) in a high mountain habitat.

We analyzed the content of the abomasum (n = 79) and small intestine (n = 83) of Spanish ibex from Sierra Nevada Natural Park, southern Spain. Fifteen species of trichostrongylid nematodes were identified, 4 of which were found for the first time in this host, i.e., Nematodirus fillicollis, N. oiratianus, Ostertagia lyrata, and O. ostertagi. Teladorsagia circumcincta and Marshallagia marshalli were the most abundant abomasal species, whereas N. abnormalis, N. davtiani, and N. oiratianus were dominant in the small intestine. Counts of both abomasal and intestinal nematodes were generally low (year-round-median = 292 and 94 worms, respectively), and significantly lower numbers of M. marshalli, N. davtiani, and N. oiratianus were found in summer. No sex-related differences in helminth abundance were found, but young ibex harbored significantly more N. davtiani and N. oiratianus than adults. The presence of scabies was not related to increased nematode counts.

Feeding habits and overlap among red fox (Vulpes vulpes) and stone marten (Martes foina) in two Mediterranean mountain habitats

Summary The feeding habits of two carnivorous opportunists, red fox ( Vulpes vulpes ) and stone marten ( Martes foina ), have been compared in two Mediterranean mountain habitats (mesic and xeric), located in the Sierra Nevada National Park (SE Spain), between April 1997 and March 1998. The analysis of scats revealed a very important interspecific trophic niche overlap in the mesic habitat. In the xeric habitat the differences were significant and the overlap moderate. Seasonal variations existed in the degree of overlap, which reached its highest level in winter in the mesic habitat and in spring in the xeric habitat. The results indicated that the availability of food in each habitat was important in determining the divergence of the diets. Thus, in the mesic habitat, competition could be possible, although it was not important enough to cause a habitat segregation. Martens seemed to be more adaptive than foxes, probably due to their smaller size and arboreal life, allowing them to exploit fruit which is not as profitable for the fox. Foxes based their diet on small mammals, carrion and cultivated fruit in both habitats. Rabbits were also seasonally important in the xeric habitat. The trophic niche breadth of foxes was higher in the mesic habitat. The inter-habitat comparison showed significant differences in the diet of martens. In the xeric habitat, martens centred their diet on small mammals and fruit of Juniperus phoenicea , Morus ulmifolius and Amelanchier ovalis , while in the mesic habitat their diet was very similar to that of foxes. The trophic niche breadth was higher in the xeric habitat than in the mesic. The habitat conditions particulary influenced the overlap of the diets and these variations were fundamentally caused by the different availability of small fruit.

Prevalence and Seasonality of Oestrus caucasicus Grunin, 1948 (Diptera: Oestridae) Parasitizing the Spanish Ibex, Capra pyrenaica (Mammalia: Artiodactyla)

Prevalence and intensity of parasitism by oestrid larvae in the Spanish ibex Capra pyrenaica were determined for a period of 2.5 yr in Sierra Nevada Natural Park, southern Spain. The most relevant result of this study was to find Oestrus caucasicus parasitizing this ungulate in a geographical location far from its previously known distribution, e.g., the Caucasus mountain range and central Asia. Larvae were found within 74% of the heads examined (n = 180). Prevalence was higher in females and in older animals. Lowest prevalence occurred during the summer months. The mean intensity (+/- SD) was 25.4 +/- 27.3 larvae and was similar in both host sexes. The number of larvae increased with host age and reached the highest intensities in winter, during December and January.

Population dynamic of the Spanish ibex Capra pyrenaica in Sierra Nevada Natural Park (southern Spain)

The whole area of distribution of the Spanish ibex Capra pyrenaica Schinz, 1838 population of Sierra Nevada Natural Park was surveyed for the first time during July-August 1993 and the densities were estimated by using the line transects method.

The Spectacled Bear in the Sierra Nevada National Park of Venezuela

The Spectacled Bear in the Sierra Nevada National Park of Venezuela