Functional morphology of a sarcocaulescent desert scrub in the bay of La Paz, Baja California Sur, Mexico

Perea, M.C.; Ezcurra, Exequiel; Luz, José Luis León de la

doi:10.1016/j.jaridenv.2005.01.004

Cited by 14 publications

(9 citation statements)

References 21 publications

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“…Alkalinity, pH, water temperature and carbon isotope ( 13 C and 14 C) data were used to make these age calculations. The model approach corrects the age for dissolution with ''dead'' carbon derived from the aquifer matrix, assuming the following parameters to account for the pristine arid sarcocauleschent scrub vegetation (Perea et al 2005;Michener and Lajtha 2007;Rodríguez-Estrella et al 1998): initial activity; isotope fractionation factors after Vogel et al (1970), Mook et al (1974) and Deines et al (1974); d 13 C carbonates of 0 % VPDB and d 13 C soil CO 2 of -19 % VPDB. If a particular model resulted in an unreasonable (negative) age, the adjusted age was designated as either modern (recharge after the mid-1950s), premodern (recharge prior to the mid-1950s), or as a mixture of modern and pre-modern water with respect to 14 C based on evaluating CFC tracers (Gardner and Heilweil 2014).…”

Section: Discussionmentioning

confidence: 99%

Isotope signatures and hydrochemistry as tools in assessing groundwater occurrence and dynamics in a coastal arid aquifer

et al. 2016

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Groundwater from the La Paz arid coastal aquifer in Baja California, Mexico, is essentially the only source of drinking water for the local population and tourists, as well as irrigation water for agricultural needs. The intensive exploitation of the aquifer and water cycling has resulted in groundwater abatement (up to 10 m) and high salinity (up to *5800 mg l -1 ). A study using hydrochemistry, isotopic (deuterium, oxygen-18 and carbon-14) and gaseous tracers (chlorofluorocarbons CFC-11, CFC-12, CFC-113), as well as multivariate statistics, was developed to elucidate groundwater composition, flow and occurrence. Groundwater is of meteoric origin, and a large proportion is subject to evaporation. The primary natural recharge is generated in the El Novillo and Las Cruces ranges, and groundwater subsequently flows in a SE-NW direction toward the coast. The initial water type is the result of discordant dissolution of silicate minerals and ion exchange on soils. In the lower plain portion, the aquifer system is recharged from irrigation return flow and seawater intrusion, which significantly affects groundwater chemistry. Nitrate and chloride concentrations indicate that groundwater is highly affected by an overuse of fertilizers in agricultural activities, but there is little effect from urban activities. Seawater intrusion has progressed rapidly during the past decade, and the impact currently extends 13 km inland. Radiocarbon residence time calculations suggest that groundwater is modern, with the exception of Chametla and El Centerario sites in the central and western lowlands with ages of up to *5000 years. These waters indicate an additional recharge source for the upconing of fossil groundwater or regional flow.

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Section: Discussionmentioning

confidence: 99%

Isotope signatures and hydrochemistry as tools in assessing groundwater occurrence and dynamics in a coastal arid aquifer

et al. 2016

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“…Perea et al . () found four morphological groups in the study area: (1) crassicaulescent plants, or succulent cacti, (2) sarcocaulescent species, (3) woody trees, and (4) woody shrubs. Cacti and sarcocaulescent plants dominate in the open scrub, woody shrubs dominate in the clustered scrub, and woody trees, together with all the previous life forms, form the more mesic closed scrub.…”

Section: Methodsmentioning

confidence: 97%

Carbon dioxide exchange over multiple temporal scales in an arid shrub ecosystem near La Paz, Baja California Sur, Mexico

Bell¹,

Menzer

Troyo-Diéquez³

et al. 2012

Global Change Biology

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Arid environments represent 30% of the global terrestrial surface, but are largely under-represented in studies of ecosystem carbon flux. Less than 2% of all FLUXNET eddy covariance sites exist in a hot desert climate. Long-term datasets of these regions are vital for capturing the seasonal and interannual variability that occur due to episodic precipitation events and climate change, which drive fluctuations in soil moisture and temperature patterns. The objectives of this study were to determine the meteorological variables that drive carbon flux on diel, seasonal, and annual scales and to determine how precipitation events control annual net ecosystem exchange (NEE). Patterns of NEE from 2002 to 2008 were investigated, providing a record with multiple replicates of seasons and conditions. Precipitation was extremely variable (55-339 mm) during the study period, and reduced precipitation in later years (2004)(2005)(2006)(2007)(2008) appears to have resulted in annual moderate to large carbon sources (62-258 g C m À2 yr À1 ) in contrast to the previously reported sink (2002)(2003). Variations in photosynthetically active radiation were found to principally drive variations in carbon uptake during the wet growing season while increased soil temperatures at a 5 cm depth stimulated carbon loss during the dry dormant season. Monthly NEE was primarily driven by soil moisture at a 5 cm depth, and years with a higher magnitude of precipitation events showed a longer growing season with annual net carbon uptake, whereas years with lower magnitude had drier soils and displayed short growing seasons with annual net carbon loss. Increased precipitation frequency was associated with increased annual NEE, which may be a function of increased microbial respiration to more small precipitation events. Annual precipitation frequency and magnitude were found to have effects on the interannual variability of NEE for up to 2 years.

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“…Woody clusters less than 4 m high; branching behaves as secondary vegetation of floodland areas, representative of tropical and arid areas Maya and Arriaga 1996;Moreno-Casasola 2006;Perea et al 2005).…”

Section: Scrubmentioning

confidence: 99%

An examination of coastal conservation by remote sensing in Baja California Sur, México

et al. 2015

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The state of Baja California Sur (BCS), Mexico, has a coastline of 2131 km with eight Protected Natural Areas (PNA) (33,075 km 2 ) mainly located in the coastal zone. Here, we (1) review the current status of the diversity and distribution of coastal ecosystems in BCS, (2) assess the composition and coverage of these ecosystems in PNAs, and (3) identify coastal ecosystems of special interest for conservation. The combination of spatial analysis techniques was carried out using LandSat TM images and GIS processing, considering ecoregions and ecosystems in the coastal zone, as well as through the application of an ecosystem diversity index. In the BCS coastal zone, 11 ecosystems were identified: scrub, coastal water body, riparian, bare soil, halophyte, beach, salt flat, mangrove, salt marsh, coral reef, and seagrass. The ecosystem diversity in BCS results from the coastal features that differentiate the Pacific and the Gulf coasts. PNAs include 17 % of coastal ecosystems. Bahia Magdalena (Pacific) and Bahia Concepción (Gulf of California), which are key for conservation (including mangroves and seagrasses), should be considered either for classification as PNAs or for inclusion in coastal management programs. The combination of remote sensing and GIS with biogeographic and ecosystemic approaches in our study enabled to determine ecosystem diversity and set coastal conservation priorities in Baja California Sur, Mexico. Specifically, coastal ecosystems that are not currently included within PNAs and which should be considered as conservation priorities were identified.

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Functional morphology of a sarcocaulescent desert scrub in the bay of La Paz, Baja California Sur, Mexico

Cited by 14 publications

References 21 publications

Isotope signatures and hydrochemistry as tools in assessing groundwater occurrence and dynamics in a coastal arid aquifer

Isotope signatures and hydrochemistry as tools in assessing groundwater occurrence and dynamics in a coastal arid aquifer

Carbon dioxide exchange over multiple temporal scales in an arid shrub ecosystem near La Paz, Baja California Sur, Mexico

An examination of coastal conservation by remote sensing in Baja California Sur, México

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