Alpine bogs of southern Spain show human-induced environmental change superimposed on long-term natural variations

Abstract

Recent studies have proved that high elevation environments, especially remote wetlands, are exceptional ecological sensors of global change. For example, European glaciers have retreated during the 20th century while the Sierra Nevada National Park in southern Spain witnessed the first complete disappearance of modern glaciers in Europe. Given that the effects of climatic fluctuations on local ecosystems are complex in these sensitive alpine areas, it is crucial to identify their long-term natural trends, ecological thresholds, and responses to human impact. In this study, the geochemical records from two adjacent alpine bogs in the protected Sierra Nevada National Park reveal different sensitivities and long-term environmental responses, despite similar natural forcings, such as solar radiation and the North Atlantic Oscillation, during the late Holocene. After the Industrial Revolution both bogs registered an independent, abrupt and enhanced response to the anthropogenic forcing, at the same time that the last glaciers disappeared. The different response recorded at each site suggests that the National Park and land managers of similar regions need to consider landscape and environmental evolution in addition to changing climate to fully understand implications of climate and human influence.

Holocene climate aridification trend and human impact interrupted by millennial- and centennial-scale climate fluctuations from a new sedimentary record from Padul (Sierra Nevada, southern Iberian Peninsula)

“…A similar cycle (between 168 and 174 years) was also described in the alpine pollen record from Borreguil de la Caldera in the Sierra Nevada (Ramos-Román et al, 2016), which shows that it is a significant cyclical pattern in climate, and probably precipitation, in the area. This cycle could be related to the previously described ∼ 170-year cycle in the NAO index (Olsen et al, 2012), which would agree with the hypothesis of the NAO controlling millennial-and centennial-scale environmental variability during the late Holocene in the area (Ramos-Román et al, 2016;García-Alix et al, 2017).…”

Fire, vegetation, and Holocene climate in a southeastern Tibetan lake: a multi-biomarker reconstruction from Paru Co

“…The 17 priority PAHs (according to US ATSDR, 1995) plus retene, n-alkanes (from C 10 to C 35 ), and FeSts (coprostanol, epi-coprostanol, cholesterol, 5α-cholestanol, sitosterol, sitostanol) were analysed with gas chromatography (6890-N GC system) coupled to a single quadrupole mass spectrometer (MS 5975, Agilent Technologies, Santa Clara, CA, USA) Battistel et al, 2015;Gregoris et al, 2014;Martino, 2016;Piazza et al, 2013). Each analysis used the same capillary column (HP5-MS (5 %-phenyl)-methylpolysiloxane, Agilent Technologies, Santa Clara, CA, USA).…”

“…Target molecules with their respective analysed ions and method detection limits (MDL) are listed in Table 1. Further method details and quality assurance are available in previously published work Battistel et al, 2015;Gregoris et al, 2014;Kirchgeorg et al, 2014;Martino, 2016;Piazza et al, 2013). Chromatographic peak identification and calculations were performed using the Chromeleon ™ 6.8 Chromatography Data System Software (Thermo Scientific, Waltham, USA) and Agilent G1701DA GC/MSD ChemStation (Agilent Technologies, Santa Clara, CA, USA).…”

“…The Paru Co CPI values peak around 10 cal kyr BP, in the period between 7.8 and 3.5 cal kyr BP, and at 2.3 cal kyr BP, with values up to 41.2, similar to the peak distributions of L / M. Another argument for the relationship between CPI and MA fire is the fact that lower temperature fires (MAs) essentially steam-distil the vascular plant lipids into the smoke, while high-temperature fires (PAHs) can result in a decrease in the CPI, potentially due to the thermal generation of nalkanes of lower CPI from macromolecular material (Schefuss et al, 2003;Standley and Simoneit, 1987). In addition, the distance from the vegetation to the sediments may influence the CPI record as plants that are in or near the water pools contain shorter carbon chains, whereas more distant plants have higher CPI values (García-Alix et al, 2017). Using these considerations, we assume that when CPI and L / M are parallel to each other, they record both fire from the surrounding areas as well as from near the lake catchment.…”

Multiproxy reconstruction of Holocene glaciers in Sierra Nevada (south Spain)

“…Lake sediments confirm the existence of a glacier at the northern cirque of the Mulhacén peak at 2.8-2.7, 1.4-1.2 cal ka BP, and 510 and 240 cal yr BP (Oliva and Gómez-Ortiz 2012), although it has not been yet confirmed by surface exposure dates. The presence of a glacier during the Late Holocene must have been driven by colder and wetter conditions than present, despite the long-term aridity trend detected in other lacustrine records of the massif (Oliva 2009;Oliva et al 2010;García-Alix et al 2017). Based on La Mosca lake record, the cirque has been icefree during most of the Late Holocene, with a glacier existing in the catchment only less than 20 percent of the time of the last three millennia.…”