Agriculture, water mismanagement and ecosystem transformations in the Cuatrociénegas Valley in the Chihuahuan Desert, Mexico Irene Pisanty María Cristina Pérez y Sosa Gabriel Gálvez Departamento de Ecología y Recursos Naturales Facultad de Ciencias UNAM
Cuatrociénegas, Coahuila
climate 55 35 Rainfall (mm) 50 45 40 35 30 25 20 15 30 25 20 15 10 Temperature ( C) 10 5 0 Oct oct Jan ene Feb feb Mar mar Apr abril May may Jun junio July julio Aug agost Sept sept Oct Nov oct nov Dec Jan dic ene BWh Time (2007 2009) 5 55.0 0 50.0 45.0 Precipitation (mm) Rainfall (mm) 40.0 35.0 30.0 25.0 20.0 15.0 10.0 5.0 35.0 30.0 25.0 20.0 15.0 10.0 5.0 Temperature ( C) 0.0 Jan Feb March April May Jun July Agust Sept Oct Nov Dec 0.0 Time (20 years)
Ecological importance of the Cuatrociénegas Valley Plants 860 species 23 endemic species Animals 250 species 56 endemic species
Different microenvironments Water bodies spring heads ponds streams terminal lakes complex underground water system Riparian vegetation Halophilous vegetation Gypsum dunes Desertic shrublands
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Churince System sampling area 1. Poza Churince 2. Poza Bonita 3. Laguna Intermedia 4. Laguna Churince (Laguna Grande) 5. Río Churince Poza Churince and Poza Bonita are connected underground.
Poza Bonita
Poza Churince
Laguna intermedia
Water level Poza Bonita average water level Level (m) 0.450 0.400 0.350 0.300 0.250 0.200 0.150 0.100 0.050 0.000 April-07 June-07 Agust-07 Oct-07 Dec- 07 Feb-08 April-08 June-08 Agust-08 Oct-08 Dec- 08 Feb-09 April-09 June-09 Agust-09 Time Poza Churice average water level 0.300 water level (m) 0.250 0.200 0.150 0.100 0.050 0.000 Dec-06 Feb-07 April-07 June-07 Agust-07 Oct-07 Dec-07 Feb-08 April-08 June-08 Agust-08 Nov-08 Jan-09 March-09 May-09 July-09 time
Laguna Churince 1973
Laguna Churince 1977
Laguna Churince 1986
1990
1992
1996
2000
2004
2006
Laguna Churince: disappearing is a fact Pérdida de superficie de Laguna Churince 700000 600000 Superficie (m²) 500000 400000 300000 200000 100000 0 1973 1977 1986 1990 1992 1996 2000 2004 2006 Años
changes a b c d
Not many measurments, but.
El Hundido
Measuring parameters depth water level length width
Percentages of sinkholes with and without water 100% 90% 80% 70% 60% 50% 40% with water without water 30% 20% 10% 0% January 08 March May July September November January 09 time
Meses cálidos Figura 9. Dinámica de abras: número total y formación de abras nuevas
Sinkholes: size categories Warm months Sinkoholes (%) Oct Jan Mar May June Aug Oct Dec Time
Annual transition probabilities for sinkholes categorized by size (area) General annual transition probabilities Permanence 0.625 Growth to next category 0.335 Growth to following categories 0.005 Retrogression 0.053
Projected size structure of sinkholes in the Churince System Sinkholes (%) Time (years)
species in sinkholes
Vegetation strips
Samolus ebractetus var. coahuilensis
A brave colonizer
Samolus ebracteatus var. coahuilensis Green rosettes inflorescence Dry rosettes
growth Branches (rosettes) Underground meristems rizome root
Ramet (physologically independent)
Structure of the population of S. ebracteatus, based on size categories
Fecundity Category Reproductive individuals Average number of seeds Individuals per category (March 2009) 1 0 0 3 2 0 0 23 3 15 16426.1631 85 4 41 21523.9379 105 5 120 74200.9437 178 6 125 68536.7495 139 7 57 33560.3505 61 8 53 29312.2049 57
Matriz anual de transición (mar 08 mar 09) 1 2 3 4 5 6 7 8 1 0 0 0.00074 0.00056 0.00016 0.00018 0.00036 0.00041 2 0.03571 0.04167 0.01 0.01961 0.01657 0.03727 0.03797 0.09574 3 0.14286 0.25000 0.16 0.06863 0.07182 0.08696 0.07595 0.17021 4 0.28571 0.20833 0.27 0.12745 0.15470 0.05590 0.08861 0.10638 5 0.03571 0.16667 0.19 0.39216 0.32597 0.21739 0.11392 0.11702 6 0.03571 0.04167 0.07 0.09804 0.24862 0.34783 0.15190 0.07447 7 0.03571 0 0 0.01961 0.01105 0.15528 0.26582 0.10638 8 0.03571 0 0 0 0.02210 0.05590 0.20253 0.27660
Life cycle diagram of Samolus ebracteatus 0.00447 0.01118 0.00248 0.02237 0.02237 0 1 2 3 4 5 6 7 8 0.3571 0.25 0.2727 0.3960 0.2528 0.1623 0.2105 0.0416 0.1616 0.1287 0.3314 0.3636 0.2763 0.0909 0.0693 0.1573 0.2272 0.1578 0.1190 0.0196 0.0718 0.0559 0.0886 0.2173 0.1139 0.0759 0.0744 0.1170 0.1063
Some conclusions Sinkholes of different sizes will probably continue to form as long as water continues to flow from Rio Churince towards the flatland that surrounds it, probably caused by an unstable underground system This process is related to the decrease of the water flow from Poza Churince The decrease seems to be related with underwater destabilization due to water overexploitation in the reserve and in the surrounding valleys
The projection model shows that, if the conditions prevailing when we started this study persist in time, the water bodies of the Churince System will be surrounded by big soil depressions that will be colonized by species that can both take advantage of the humidity these riparian habitats offer, and tolerate high salinity levels.
In other words, the loss of water from the stream and the resulting formation of sinkholes will eventually transform this area into a set of big holes resulting from a general destabilization of the water system and the soil, which will collapse repeatedly and constantly. However, the process of sinkhole formation could decrease progressively if the different parts of the system continue to dry through time
Sinkhole formation can be used as an early warning system for underground water variations implying the loss of surface water Some species, as Samolus ebractatus are indicators of humid microhabitats; changes in their distribution, abundance and population dynamics are indicators of variation in physical parameters
Water bodies 1990
Water bodies 2000
No doubt Even if the terminal causes of this process are still being determined (and discussed), urgent action is needed to preserve the wetlands in this extraordinary system
Irene Pisanty ipisanty@servidor.unam.mx tel +52(55)56 22 49 12 Gracias! Thank you!
Riqueza Composición específica Nomenclatura Familia Especie Se Primulaceae Samolus ebracteatus Perenne Bm Cyperaceae Bolboschoenus maritimus Perenne Jp Poaceae Jouvea pilosa Perenne Fc Asteraceae Flaveria chlorifola Perenne Jc Asteraceae Jaumea carnosa. Perenne Sc Poaceae Sporobolus coahuilensis. Perenne A Fabaceae Acacia sp Perenne St Gentianaceae Sabatia tuberculosa Anual Ee Gentianaceae Eustoma exaltatum Anual