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Long-term soil temperature dynamics in the Sierra Nevada, Spain
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Orientador(es)
Resumo(s)
Soil temperatures play a key role on the dynamics of geomorphological processes in periglacial environments.
However, little is known about soil thermal dynamics in periglacial environments of semiarid mid-latitude
mountains, where seasonal frost is dominant.
From September 2006 to August 2012we havemonitored soil temperatures at different depths (2, 10, 20, 50 and
100 cm) in a solifluction landformlocated at 3005 m.a.s.l. in the summit area of the Sierra Nevada (South Spain).
Mean annual temperatures in the firstmeter of the soil ranged from3.6 to 3.9 °Cwhile themean annual air temperature
at the nearby Veleta peak was 0.08 °C. Therefore, these data point out the inexistence of widespread
permafrost conditions today in this massif. Seasonal frost controls the geomorphodynamics even in the highest
lands. Climate conditions have shown a large interannual variability, as it is characteristic in a high mountainous
Mediterranean environment. These variations are reflected in the patterns of soil thermal dynamics. The depth
and duration of the frozen layer are strongly conditioned by the thickness of the snow cover. The date of the
first significant snowfalls conditioned the beginning and rhythm of freezing of the soil. Wet years resulted in a
thick snow cover which insulated the ground from external climate oscillations and favored a shallow frost
layer (2008–2009, 2009–2010 and 2010–2011). On the other hand, years with low precipitations promoted
deeper freezing of the soil down to 60–70 cm extending until late May or early June (2006–2007, 2007–2008
and 2011–2012). When snow melted a high increase of temperatures of 10–12 °C in few weeks was recorded
at all depths. At this time of the year, periglacial activity is enhanced due to higher water availability and the existence
of freeze–thaw cycles. These were recorded mostly in spring and autumn in the first 50 cm depth of the
soil, ranging from 9.8 days (at 2 cm) to 3.7 days (at 50 cm).
However, the inactivity of solifluction landforms suggests that the combination of present-day soil temperatures
together with moisture conditions is not favorable to promote solifluction activity in the periglacial belt of the
Sierra Nevada.
Future climate scenarios point to a temperature increase and precipitation decrease in the area, which would
entail deeper but shorter frozen soil layers. These conditions would not be favorable for active periglacial slope
processes in the Sierra Nevada.
Descrição
Palavras-chave
Sierra Nevada Periglacial environment Solifluction processes Soil temperatures Seasonal frost Snow cover
Contexto Educativo
Citação
Oliva, Marc, Gómez Ortiz, Antonio, Salvador, Ferran, Salvà, Montserrat, Pereira, Paulo & Geraldes, Miguel. (2014). Long-term soil temperature dynamics in the Sierra Nevada, Spain. Geoderma, 235–236, 170-181. https://doi.org/10.1016/j.geoderma.2014.07.012. ISSN: 0016-7061
Editora
Elsevier