Successional stage after land abandonment modulates fire severity and post-fire recovery in a Mediterranean mountain landscape

This study analyses the effect of successional stage after farmland terrace abandonment on post-fire plant recovery in a Mediterranean landscape. Specific objectives of the study were to (1) compare fuel characteristics and fire severity in three successional stages after farmland abandonment – dry grassland, dense shrubland and pine stands; (2) analyse the effect of pre-fire successional stage and fire severity on vegetation recovery and (3) analyse the relative vulnerability (i.e. potential for ecosystem shift and soil degradation) to wildfires of the successional stages. We assessed 30 abandoned terraces (15 unburned and 15 burned), with diverse successional stages, on the Xortà Range (south-east Spain). Post-fire recovery was measured 1, 4 and 7 years after fire. The successional stages varied in aboveground biomass, litter amount, vertical structure and continuity of plant cover, and flammability. Dry grassland showed the lowest fire severity, whereas no differences in severity were found between shrubland and pine stands. One year after fire, plant cover was inversely related to fire severity; this relationship attenuated with time after fire. Post-fire recovery of pine stands and shrubland led in both cases to shrublands, contributing to landscape homogenisation. The pine stands showed the largest changes in composition due to fire and the lowest post-fire plant recovery – a sign of high vulnerability to fire.

Seguimiento de la liebre ibérica (Lepus granatensis ROSENHAUER, 1856) en la Sierra de Mariola (Alicante-Valencia)

La liebre ibérica (Lepus granatensis) es una especie de gran valor en los ecosistemas mediterráneos españoles y por esta razón, su conocimiento ecológico y su relación con los factores que influyen en la heterogeneidad espacial son esenciales para su conservación y manejo. El objetivo de este trabajo es conocer las variaciones de la abundancia de la liebre ibérica en el Parque Natural de la Sierra de Mariola, situado entre las provincias de Alicante y Valencia, en el periodo 2009-2010, y su distribución en las principales matrices del paisaje de una zona de montaña del mediterráneo peninsular. Las abundancias relativas de liebre se han obtenido a partir de transectos estratificados de 1.000 m de longitud. El mayor índice kilométrico de abundancia (IKA) de liebres tiene lugar en primavera (IKA medio de 0,26 liebres/km), y disminuye hasta el invierno (IKA medio de 0,075 liebres/km). La mayor abundancia de liebres se obtiene en la matriz de cultivos de secano (IKA medio de 0,32 liebres/km). Las matrices de vegetación natural y abandono presentan bajo número de liebres, con valores de IKA medios de 0,06 y 0,04 liebres/km respectivamente.

Estudio preliminar sobre la abundancia y distribución de la perdiz roja (Alectoris rufa Linnaeus, 1758) en el Parque Natural Sierra de Mariola (Alicante-Valencia)

El presente estudio tiene como objeto analizar la abundancia y distribución de la perdiz roja en función de las diferentes matrices de usos del suelo. Parte del trabajo se ha centrado en la Finca Buixcarró, finca forestal de 652 has. de superficie, cuya propiedad y gestión pertenecen a la Fundación de la Comunidad Valenciana C.V. Victoria Laporta Carbonell. La zona de estudio se encuentra en la Sierra de Mariola es un Parque Natural de 17.500 ha situado entre las provincias de Alicante y Valencia que cuenta con una vegetación climática de carrascal de termotipo mesomediterráneo y ombrotipo subhúmedo. Entre marzo y junio del 2011 se han realizado un total de 12 itinerarios de censo de 500 m de longitud, distribuidos en las diferentes matrices de usos del suelo (matorral, bosque, cultivo y zona de regeneración). El análisis de los resultados, muestra una mayor abundancia de los individuos de la población en zonas de matorral denso y bajo (IKA=1,33), siendo visibles a primeras horas de la mañana en sendas y/o bordes de caminos; y así mismo, un mayor contacto visual en días parcialmente despejados y sin viento. También se han hecho escuchas puntuales en la zona de regeneración arbolado post-incendio.

Feedbacks between vegetation pattern and resource loss dramatically decrease ecosystem resilience and restoration potential in a simple dryland model

Conceptual frameworks of dryland degradation commonly include ecohydrological feedbacks between landscape spatial organization and resource loss, so that decreasing cover and size of vegetation patches result in higher water and soil losses, which lead to further vegetation loss. However, the impacts of these feedbacks on dryland dynamics in response to external stress have barely been tested. Using a spatially-explicit model, we represented feedbacks between vegetation pattern and landscape resource loss by establishing a negative dependence of plant establishment on the connectivity of runoff-source areas (e.g., bare soils). We assessed the impact of various feedback strengths on the response of dryland ecosystems to changing external conditions. In general, for a given external pressure, these connectivity-mediated feedbacks decrease vegetation cover at equilibrium, which indicates a decrease in ecosystem resistance. Along a gradient of gradual increase of environmental pressure (e.g., aridity), the connectivity-mediated feedbacks decrease the amount of pressure required to cause a critical shift to a degraded state (ecosystem resilience). If environmental conditions improve, these feedbacks increase the pressure release needed to achieve the ecosystem recovery (restoration potential). The impact of these feedbacks on dryland response to external stress is markedly non-linear, which relies on the non-linear negative relationship between bare-soil connectivity and vegetation cover. Modelling studies on dryland vegetation dynamics not accounting for the connectivity-mediated feedbacks studied here may overestimate the resistance, resilience and restoration potential of drylands in response to environmental and human pressures. Our results also suggest that changes in vegetation pattern and associated hydrological connectivity may be more informative early-warning indicators of dryland degradation than changes in vegetation cover.

Irrigation canals in a semi-arid agricultural landscape surrounded by wetlands: Their role as a habitat for birds during the breeding season

Traditional water supply systems in semi-arid agrarian ecosystems, mainly irrigation canals, contribute to the diversity of the landscape and influence the composition of species. To evaluate their effect on bird communities in the breeding season, we selected a rural area in southeastern Spain, where an intricate and extensive network of irrigation canals and cultivated areas is located between two wetlands declared as Natural Parks. Birds were counted at representative points distributed throughout the canal network at which we recorded several variables related to the physical features, the vertical and horizontal structure of associated vegetation, reed development (Phragmites australis) and land use in the neighboring areas. We detected 37 bird species, most of which were also breeding in the wetlands nearby. We used Hierarchical Partitioning analyses to identify the variables most strongly related to the probability of the presence of selected species and species richness. Vegetation cover and height close to the canals, together with reed development, were the most important types of variables explaining species presence and richness. We found that current management practices for reeds in canals are not well-suited for biodiversity conservation. We therefore propose alternatives that could be implemented in the area in cooperation with stakeholders.