Analysis of Land Use and Land Cover Changes and Evaluation of Natural Generation and Potential Restoration Areas in the Mexican Huasteca Region ()
Received November 21st, 2013; revised December 28th, 2013; accepted January 19th, 2014
Figure 1.
Map of the study area.
Flowchart of the stages developed in the analysis of land cover and land use change.
cover change for the different classes (Table 1).
Finally, to estimate the areas that were subject to the natural regeneration of vegetation, those covers were quantified and mapped which had reached a primary forest stratum. To identi- fy restoration areas were recognized forest areas changed to other land uses (1976-2007) and which had a restoration poten- tial.
Results and Discussion
Land Use and Land Cover
The dynamics of land use and land cover in the Huasteca re-
gion can be reconstructed for a timeframe of 31 years (Table 2) (Figure 3), based on the analysis of the obtained information.
Table 2 indicates that the biggest areas that were mapped and quantified correspond to agriculture and pasture, repre- senting approximately 60% of the surface of the Huasteca re- gion in the year 2007. It can be observed that the share of agri- cultural land has increased by 50% over the past 31 years. This shows that agricultural modernization and industrialization, the increase of livestock, and the demand for wood and wood- derived products have an important stake in the considerable increase of land cover types that were induced by humans (Aguilar-Robledo, 2001).
Land use and land cover in the Huasteca region (1976-2007).
Source: Pontius et al., 2004 y FAO, 1996.
Obtained data demonstrates that for the studied years, forest cover (rain forest, forest and scrubland) in particular has been reduced, as affirmed by Quinteros (2012).
Land Use and Land Cover Changes
The most reliable statistical data for the analysis of land use and land cover changes use for the years of study correspond to data on the vegetal cover, while the least reliable data refers to water and urban areas. Data of land use and land cover shows slight imprecision with regard to the transition, which has also occurred in other analysis on land cover and land use change in Mexico (Velázquez et al., 2002). Nonetheless, reasonable evi- dence of LUCC was found when crossing t1-t2, t2-t3 and t3-t4, while also taking account of the particular dynamics of the ecosystems that had been analyzed.
Of the changes that occurred between t1-t2, the increase in agriculture (1.99%) as well as a change in the deforestation rate of rain forests −2.01% must be noted, the latter being higher than the general national deforestation rate for Mexico,(−0.25 and −1.02%) according to Velázquez et al., 2002, and (−0.76%) according to Mas et al., (2009). In comparison, only the state of Veracruz has a higher deforestation rate (−2.2%), and the de- forestation rate is generally lower in all other states of the Mex- ican Republic (Céspedes-Flores & Moreno-Sánchez, 2010). Fur- thermore, urban areas increased by 500% over the same time period, while areas without vegetation, despite the fact that their growth rate is merely 6.33%, have increased by 56.03 km2 (Table 3).
Between 1993 and 2002 (t2-t3), most classes of land cover and land use suffered from losses, except for agriculture, water and urban areas. The greatest loss of forest cover was registered for the categories “other types of vegetation” (−3.78%) and “rain forest” (−1.41%), again at a higher rate than the rate calculated by Velázquez et al., (2002). For other types of land cover and land use the loss was less amounting to 0.9% (Table 4).
Between 2002 and 2007 (t3-t4), the loss and gain rates of land use and land cover were much smaller than for the previous periods. A gain could be observed for the category rain forest and other vegetation with 249.55 km2 and 236.55 km2 respec- tively. Also, urban areas increased annually by 3.01%, and agri- culture by 0.86%, as reported by Algara (2009), which had an important impact on the transformation of ecosystems (Table 5).
General Changes in Land Use and Land Cover
By crossing data from four years (1976, 1993, 2002 and 2007) it can be observed that the pressure of human-induced activities on natural land cover (forest, rain forest, other vegeta- tion, scrubland and no vegetation) has increased exponentially, which translates into an increase of non-original cover (second- ary vegetation, pasture and agriculture). Despite this, in 2007
the Huasteca region still conserved approximately 10602.59 km2 of original land cover representing 16.4% of the surface (Table 6).
Furthermore, the development of total changes in land cover and land use amount to 17.84%, or 11718.82 km2 of the Huas- teca region (Table 7), as shown in detail in (Table 8).
Table 8 indicates that the main changes occurred with regard to natural covers which transformed into non-original covers, mostly in the period of time between 1976 and 1993 with 4911.88 km2, followed by 1892.5 km2 for the period of time between 2002 and 2007, and finally 1029.78 km2 for the period of time between 1993 and 2002.
In spite of this loss of natural cover, 1318.68 km2 were re- covered between 1976 and 1993, 974.18 km2 between 1993 and 2002 as well as 468.43 km2 between 2002 and 2007. The total change in land cover (17.84%) for the Huasteca region, equal- ing 11,718.82 km2, can be observed in 100% (Figure 4).
Natural Regeneration and Potential Areas for Restoration
Areas of land cover and land use that regenerated naturally to forest cover between the years 1976 and 2007 are approxi- mately 721.25 km2 of forest area and 1210.82 km2 of rain fo- rests, without taking into account changes between other forest covers. The greatest natural regeneration took place between 1976 and 1993 for both forest types. At the same time, the greatest loss of these ecosystems falls also into this timeframe (1021.66 km2 of forest area and 3235.75 km2 of rain forest). In
*Covers without a change in land use or land cover from 1976 until the year 2007. **The margin of error refers to possible inconsistencies with regard to classification; inconsistent changes in land use and land cover take into account the individual dynamics of ecosystems and problems of overlap.
*Covers without a change in land use or land cover from 1976 until the year 2007. **The margin of error refers to possible inconsistencies with regard to classification; inconsistent changes in land use and land cover take into account the individual dynamics of ecosystems and problems of overlap.
Land covers dynamics of the grouped classes for the Huasteca región, for the periods 1976-1993, 1993-2002 and 2002-2007.
total, 1310.82 km2 of forest and 4482.47 km2 of rain forest were lost or deforested between 1976 and 2007, without accounting for the change towards other types of forest cover (Figure 5). Hence, the areas that had been deforested or put to other use are an indicator of the main potential areas which should be restored in the region in order to restore the forest cover (Figure 5).
Conclusion
It can be concluded that the thematic maps illustrating changes in land cover and land use for the period of study (1976-2007), and that were created based on GIS methods and
techniques, are adequate for the evaluation and the analysis of the changes that have occurred in the Huasteca region.
In the analysis of land use and land cover changes, more re- liable statistical results correspond to vegetation cover, while the least reliable appear to be the water and urban area classes, the same categories that presents small inaccuracies in the tran- sitions of changes.
Analysis carried out based on a cross-tabulation matrix de- monstrated that agriculture and pasture in particular have mod- ified the biophysical landscape of the Huasteca over the period of time from 1976 until 1993.
Deforestation and natural regeneration of forest cover in the Huasteca region, 1976-2007.
Deforestation rates for rain forests, forests, scrublands and other types of vegetation were also higher than the national deforestation rates reported for México by other authors, even though for the period of time between 2002 and 2007 a back- ward trend could be observed.
The analysis which measured the land cover change (natural land cover and non-original land cover), we envisioned that non-original coverage increased by 7834.16 km2, and natural land cover only recovered 2761.29 km2 in the same period of 31 years. Furthermore, this method showed that 62.67% of the surface of the Huasteca region had been modified by human activities before the year 1976, and from 1976 until 2007 changes affected 17.84% of the studied area.
It was also demonstrated that the greatest loss of forest cover in the Huasteca between 1976 and 2007 amounted to 1310.82 km2 for forests and 4482.47 km2 for rain forests, while the na- tural regeneration of non-forest covers to forest covers made up 721.25 km2 for forests and 1210.82 km2 for rain forests.
Between the years 1976 and 2007 an area of approximately 1932.07 km2 regenerated naturally to forest cover (forests and rainforests), and 5739.29 km2 were identified as potential areas for forest restoration.
References