Resumo

PEREZ-VEGA, Azucena; REGIL GARCIA, Héctor Hugo  e  MAS, Jean François. Environmental Degradation from Land-Cover and Use Change Processes from a Spatial Perspective in the State of Guanajuato, Mexico. Invest. Geog [online]. 2020, n.103, e60150.  Epub 09-Mar-2021. ISSN 2448-7279.  https://doi.org/10.14350/rig.60150.

The present study analyzed land cover/use changes in the state of Guanajuato by identifying transformation and environmental degradation processes since it is one of the states with the largest transformed area since colonial times. It has an extensive plain in the southern portion of vertisols soils, considered the most productive soils in the country. The present work addressed the transformations of land cover in the state of Guanajuato, analyzing three time periods of INEGI land-use and vegetation mapping; 2002-2007, 2007-2011, and 2011-2014. We used methods to assess rates of change, intensity of change, and the trajectories of the change sequences of land covers. The highest annual rates of relative loss and percent intensity of change occurred in arid and deciduous ecosystems such as Mezq -3.6%, VSA SBC -2.1%, BQ -1.4, VSA Mezq -1.3% and Pz nat -1.0% in the first and -1.1% in the third periods, with a sequence of change toward Agri t and Pz ind established on foothills and hills.

The main intensities of change at the interval level occurred during 2002-2007. The anthropic covers with the highest relative annual rate of profit were AH and Pz ind with 1.5%; AH showed very high values of 5.4%, 4.9%, and 11.2% for each period, replacing considerable areas of Agri r on fertile plains land. Agri t and Agri r showed very low percentages of relative rates of change but very high absolute rates of change during the period 2002-2007. A new area of Agri r was developed during this period to the northeast of the municipality of Dolores Hidalgo and southwest of San Luis de la Paz, coinciding with a high subterranean water reduction of up to -4.9 m between 2002 and 2007. While in the southeastern portion of the state in the Valle de Acámbaro aquifer, the abatement levels showed a recovery of 3.3 m for the year 2007 after the excess extraction in the year 2002. The sequences of change between Agri t to Agri r, later returning to Agri t in some cases, are intimately linked to the availability of groundwater that supplies up to 80% water for irrigation agriculture in the state of Guanajuato. Agri r decreased in area for the last two periods and Agri t loss area in the last period.

Deforestation processes take place on foothills and hills; these have not decreased considerably, as still represent less than half between the first and last periods. Degradation represents more than half of the area in the same periods.

Unfortunately, vegetation recovery processes were reduced three-fold between the last and first periods; these processes developed in foothills and hills, as well as in plains with smaller surfaces.

The state of Guanajuato is acknowledged for having a healthy economy, ranked seventh at the national level; however, the environmental cost has been high, as it is one of the states with the largest transformed cover. The results of this study suggest that this trend will continue, posing a threat to the remnants of current ecosystems given the demand for environmental services to produce supplies for the growing local, national, and even international populations.

Palavras-chave : environmental degradation; change sequence; Guanajuato.

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