250
During the gradual closure process of lagoon Matanzas, fluvial sedimentation
associated to floods of Las Rosas brook would have also been an important factor
(Fariña et al. 2012). Appearance of species intolerant to salinity along with low
chlorine concentrations found in sediments suggest that 2400 years ago existed
moderate to low salinity conditions in lagoon Matanzas (Jenny et al. 2000). During
that lapse, sediments show at least 20 different flood periods, what would indicate
marked fluctuations in winter rains (Villa-Martínez 2002).
During the last 150 years, Villa-Martínez (2002) recognizes a deterioration of
vegetation associated to forest surrounding lagoon Matanzas, what is attributed to
anthropic activity. Notwithstanding, Fariña et al. (2012), point out that an alternative
but not excluding explanation is the decrease in precipitations detected in the sediment core from lagoon Colejuda by Valero-Garcés et al. (2010).
8.3 Some Aspects About Climate Change in Central Chile
El Yali is located in a region threatened by the effects of the contemporary climate
change. An analysis about the registers of temperature and precipitation in this
region show that temperature has risen 0.5 °C in the last 50 years, whereas annual
precipitations have decreased in a 12% during the same period, which is consistent
with global warming (Fig. 8.3). On the other hand, a recent analysis about the
response of bio-climates of the region to different climate change scenarios showed
a decrease in precipitation and an increase of temperature in Valparaiso region by
2080 (Luebert and Pliscoff 2012).
For the case of annual precipitations, it is expected to observe a latitudinal pattern of decrease in the coastal and Andean areas (a decrease that can be ~280 mm),
whereas the inner areas would present a less decrease (50–80 mm per year).
Similarly, the mean annual temperature shows a longitudinal increase pattern, with
lower values in the coastal zone (1 °C), reaching an increase of 2.4–3.5 °C in the
Andean area. Under these climatic conditions it is expected in the long term an
ascendant altitudinal displacement of vegetation floors, especially in the Andean
area, as well as a latitudinal displacement, with the intrusion of species typical of
semi-arid and arid zones in central-north Chile, especially in the coastal zone. The
recent finding of Suaeda foliosa (typically found in northern Chile) in El Yali wetland (Flores-Toro and Contreras-López 2015), extending its distribution in 300 km,
seems to be an early expression of this phenomenon. As an additional element,
centuries of agriculture in central Chile have produced a progressive degradation of
soils and a severe fragmentation of the sclerophyll forest, which has consequences
on the habitat (Grez and Bustamante-Sánchez 2006), causing a reduction of biodiversity and making the system more vulnerable to climate fluctuations and a
decrease of the available hydric resources.
A series of historical records collected in the vicinity of El Yali wetland is shown in
Table 8.1. Except the annual series of precipitations in Valparaiso (1900–2015), which
corresponds to the total precipitation during 1 year, all series were averaged or accumulated to transform into monthly averages. Combined by means correlations, the
M. Contreras-López et al.
During the gradual closure process of lagoon Matanzas, fluvial sedimentation
associated to floods of Las Rosas brook would have also been an important factor
(Fariña et al. 2012). Appearance of species intolerant to salinity along with low
chlorine concentrations found in sediments suggest that 2400 years ago existed
moderate to low salinity conditions in lagoon Matanzas (Jenny et al. 2000). During
that lapse, sediments show at least 20 different flood periods, what would indicate
marked fluctuations in winter rains (Villa-Martínez 2002).
During the last 150 years, Villa-Martínez (2002) recognizes a deterioration of
vegetation associated to forest surrounding lagoon Matanzas, what is attributed to
anthropic activity. Notwithstanding, Fariña et al. (2012), point out that an alternative
but not excluding explanation is the decrease in precipitations detected in the sediment core from lagoon Colejuda by Valero-Garcés et al. (2010).
8.3 Some Aspects About Climate Change in Central Chile
El Yali is located in a region threatened by the effects of the contemporary climate
change. An analysis about the registers of temperature and precipitation in this
region show that temperature has risen 0.5 °C in the last 50 years, whereas annual
precipitations have decreased in a 12% during the same period, which is consistent
with global warming (Fig. 8.3). On the other hand, a recent analysis about the
response of bio-climates of the region to different climate change scenarios showed
a decrease in precipitation and an increase of temperature in Valparaiso region by
2080 (Luebert and Pliscoff 2012).
For the case of annual precipitations, it is expected to observe a latitudinal pattern of decrease in the coastal and Andean areas (a decrease that can be ~280 mm),
whereas the inner areas would present a less decrease (50–80 mm per year).
Similarly, the mean annual temperature shows a longitudinal increase pattern, with
lower values in the coastal zone (1 °C), reaching an increase of 2.4–3.5 °C in the
Andean area. Under these climatic conditions it is expected in the long term an
ascendant altitudinal displacement of vegetation floors, especially in the Andean
area, as well as a latitudinal displacement, with the intrusion of species typical of
semi-arid and arid zones in central-north Chile, especially in the coastal zone. The
recent finding of Suaeda foliosa (typically found in northern Chile) in El Yali wetland (Flores-Toro and Contreras-López 2015), extending its distribution in 300 km,
seems to be an early expression of this phenomenon. As an additional element,
centuries of agriculture in central Chile have produced a progressive degradation of
soils and a severe fragmentation of the sclerophyll forest, which has consequences
on the habitat (Grez and Bustamante-Sánchez 2006), causing a reduction of biodiversity and making the system more vulnerable to climate fluctuations and a
decrease of the available hydric resources.
A series of historical records collected in the vicinity of El Yali wetland is shown in
Table 8.1. Except the annual series of precipitations in Valparaiso (1900–2015), which
corresponds to the total precipitation during 1 year, all series were averaged or accumulated to transform into monthly averages. Combined by means correlations, the
M. Contreras-López et al.