Analysis of Spatial and Temporal Evolution of Vegetation Cover in the Spanish Central Pyrenees: Role of Human Management

Abstract

A vegetation cover increase has been identified at global scales using satellite images and vegetation indices. This fact is usually explained by global climatic change processes such as CO(2) and temperature increases. Nevertheless, although these causes can be important, the role of socioeconomic transformations must be considered in some places, since in several areas of Northern Hemisphere an important change in management practices has been detected. Rural depopulation and land abandonment have reactivated the natural vegetation regeneration processes. This work analyses the vegetation evolution in the central Spanish Pyrenees from 1982 to 2000. The analysis has been done by using calibrated-NDVI temporal series from NOAA-AVHRR images. A positive and significant trend in NDVI data has been identified from 1982 to 2000 coinciding with a temperature increase in the study area. However, the spatial differences in magnitude and the sign of NDVI trends are significant. The role of land management changes in the 20th century is considered as a hypothesis to explain the spatial differences in NDVI trends. The role of land-cover and human land-uses on this process has been analyzed. The highest increment of NDVI is detected in lands affected by abandonment and human extensification. The importance of management changes in vegetation growth is discussed, and we indicate that although climate has great importance in vegetal evolution, land-management changes can not be neglected in our study area.

Impact of climate evolution and land use changes on water yield in the ebro basin

“…The subsequent abandonment of farmland, associated with depopulation, has been the most outstanding feature of the Spanish Pyrenees (Beguería et al, 2003;Lasanta et al, 2005;, and by 1970 all the fields on hillslopes had been abandoned. These areas were then recolonized by shrubs, and induced afforestation took hold in many areas that were previously cultivated and grazed (Vicente-Serrano et al, 2004). As in the Pyrenees, generalized land abandonment and subsequent revegetation processes have occurred in all the mountainous areas that enclose the Ebro basin (Lasanta et al, 2006).…”

Does wild boar rooting affect livestock grazing areas in alpine grasslands?

“…Changes in grazing practices, i.e. a decrease in extensive livestock practices and a trend towards an increase in the number of cattle and a decrease in the number of sheep in extant herds because of the crisis in transhumance systems (Luick 1998;Lasanta-Martínez et al 2005), have led to the abandonment of grazing activities in some areas mostly used for sheep herding (Vicente-Serrano 2004). On the other hand, rural abandonment and an increase in forested areas (Lasanta-Martínez et al 2005) have indirectly increased wild boar populations because boars find more abundant and persistent shelters from hunting (Herrero et al 2008).…”

Evolución de la dinámica vegetal mediante una serie de imágenes Landsat TM(1986-2011): región central de Chihuahua, México

“…En el Pirineo español Occidental, Vicente-Serrano et al (2004) encontraron un tendencia temporal positiva en los valores del NDVI para bosques y áreas con una buena cobertura vegetal, las cuales se relacionaron con un aumento en la temperatura media anual, los patrones de abandono de la tierra y procesos de revegetación natural (Lasanta et al, 2007;Hill et al, 2008). En el Pirineo Central español, Alatorre et al (2011) estudiaron la dinámica vegetal en áreas con buena cobertura vegetal, en riesgo de erosión y con erosión activa, sus resultados demostraron que el aumento de la temperatura y la variación de la cubierta de nubes durante el periodo de estudio fueron los factores más importantes en la explicación de la evolución temporal de los valores medios del NDVI (1984NDVI ( -2007 observados en las áreas con buena cobertura vegetal.…”

“…1 F). Por otra parte, el hecho de que los procesos de degradación tengan una mayor presencia en las laderas con poca insolación y la recuperación en laderas con mayor insolación está en línea con otros estudios (Lasanta et al, 2000;Vicente-Serrano et al, 2004;Lasanta y Vicente-Serrano, 2006;Pueyo y Beguería, 2007). Finalmente, de acuerdo a la disección vertical los procesos de degradación ocurren con mayor frecuencia en los piedemonte, que se caracterizan por ser zonas de transición entre distintas ocupaciones del suelo y donde se realizan la mayoría de las actividades humanas.…”

“…La mayoría de los cambios han sido causados por actividad humana, particularmente por la deforestación (Achard et al, 2002;DeFries et al, 2002;Giglio et al, 2006) y los incendios forestales (Riaño et al, 2007), por otra parte, el abandono rural y la consiguiente marginalización de algunas regiones ha contribuido al proceso de recuperación vegetal (Vicente-Serrano et al, 2004;Vicente-Serrano et al, 2006a, b;Lasanta y Vicente-Serrano, 2007;Sluiter y de Jong, 2007;Alatorre et al, 2011;Lasanta y Vicente-Serrano, 2012). Además, diferentes estudios han mostrado como las actuales tendencias climáticas pueden favorecer el incremento en la actividad vegetal sobre distintos ecosistemas del mundo (Myneni et al, 1998;Kawabata et al, 2001;Lucht et al, 2002), o descenso (Maselli, 2004;Sarris et al, 2007;Vicente-Serrano et al, 2012) de la actividad vegetal.…”