Cienegas del Rio Lerma, Toluca Valley, México

Environment

Environment

Affected by human activity

Affected by human activity

Agriculture

Agriculture

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Surrounding area

The region is characterized by a temperate sub-humid climate with summer rainfall, an average annual temperature of 12°C, and average annual precipitation ranging from 800 to 1.200 mm. The predominant soils are histosols, which feature an organic layer approximately 40-50 cm deep, formed by the accumulation of large amounts of plant material in flooded areas. In the surrounding zones, other soil types can be found, including cambisols, andosols, vertisols, and regosols.

Underwater landscape

In the Lerma wetland complex, there are areas of open, permanent water with a maximum depth of 2.5 meters, where free-floating, submerged, and floating-leaved hydrophytes thrive. Surrounding these zones are broad strips of land subjected to seasonal flooding, where the maximum depth does not exceed 1.2 meters. These areas are mainly populated by rooted emergent hydrophytes, forming dense plant communities locally known as tulares.

The extent of the lacustrine (lake-like) areas in each ciénega (marsh) is influenced by the rainfall regime. Flooding typically occurs for 6 to 8 months of the year, after which the water level gradually recedes, sometimes leaving behind soils that are merely saturated with moisture. These fluctuations in water levels have allowed for the growth of flood-tolerant terrestrial plants, which can endure short periods of inundation or high humidity.

Fish Species:

• Girardinichthys multiradiatus (Goodeidae)

Crustacean Species:

• Cambarellus montezumae (Cambaridae)

Amphibian Species:

• Ambystoma lermaense (Ambystomatidae)
• Hyla eximia (Hylidae)
• Ambystoma granulosum (Ambystomatidae)

Wetland Plants:

• Sagittaria macrophylla (Alismataceae)
• Berula erecta (Apiaceae)
• Hydrocotyle ranunculoides (Araliaceae)
• Myriophyllum aquaticum (Haloragaceae)
• Typha latifolia (Typhaceae)
• Schoenoplectus californicus (Cyperaceae)
• Arenaria paludicola (Caryophyllaceae)
• Eleocharis densa (Cyperaceae)

Aquatic Plants:

• Pontederia crassipes (Pontederiaceae)
• Ludwigia peploides (Onagraceae)

Aquatic Mosses:

• Hydromystria laevigata (Araceae)
• Azolla mexicana (Azollaceae)

Terrestrial Vegetation:

• Salix bonplandiana (Salicaceae)
• Salix babylonica (Salicaceae)

Threats to ecology

The biodiversity and very existence of the wetlands in the Ciénegas del Lerma are currently under serious threat due to numerous factors, most of which are linked to human activities.

The most significant impacts on the area include groundwater extraction leading to desiccation, land-use change for agricultural expansion and urban or industrial growth, the alteration of hydrological dynamics through the construction of levees and the diversion of inflows, fragmentation caused by urban development and highway infrastructure, water pollution from domestic and industrial wastewater, the introduction of exotic species such as carp, invasion by water hyacinth Pontederia crassipes, fires in reed beds such as Typha latifolia and Schoenoplectus californicus, and contamination from solid waste.

Riparian zone

Trees near the aquatic habitat

Few -

Bibliography

• → Investigaciones Geográficas, Boletín del Instituto de Geografía, UNAM - Análisis del uso del suelo en las Ciénegas de Lerma (1973-2008) y su impacto en la vegetación acuática. by Zepeda-Gómez, C., Nemiga, X. A., Lot-Helgueras y Madrigal-Uribe, D.
  ISBN ISSN 0188-4611, Núm. 78, 2012, pp.48-61
  
• Acta botánica Mexicana 98:23-49 - Florística y diversidad de las Ciénegas del rio Lerma, Estado de México, México by Zepeda.Gómez, C., Lot-Helguera, A., Nemigia,X. A. y Madrigal-Uribe, D.
  
• → Revista Pensarte: Crear y Recrear - Ciénegas del Lerma, la conservación de la biodiversidad by Leopoldo-Flores, I
  ISBN Núm. 82, p 21
  
• Instituto de Ecología, UNAM. México, D.F.; SEMARNAT. - Ficha Informativa de los Humedales de RAMSAR: Ciénegas de Lerma by Ceballos, G.
  

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