Search

The influence of high temperatures on germination of Cistus laurifolius and Cistus ladanifer seeds was analyzed. Seeds were subjected to different temperatures for different times, afterwards they were sowed in plastic petri dishes and monitored for germinated seeds over two months.The germination rate observed in Cistus ldanifer was greater than in Cistus laurifolius. In both species, heat increased germination percentages. For Cistus laurifolius higher temperatures or longer exposure times were needed. Germination percentages of Cistus ladanifer were lower when heat exposure time was 15 minutes.It must be emphasized that germination occurred when seeds were not treated, while seeds exposed to 150�C for 5 minutes or more did not germinate.

Early post-fire structural dynamics in three Quercus pyrenaica communities after intense fires was studied. In the first year there is a marked domination of perennial species (herbaceous or woody); afterwards, herbaceous species tend to decrease in importance and ligneous species increase. Changes in species diversity were analysed as an indicator of recovery and stability in the communities. An increase was observed in the second year, and then diversity was maintained or reduced slightly in the third and fourth years. Spatial heterogeneity tends to diminish with time.

Post-fire regeneration is studied in forty-three aormrunities of Quercus pyrenaica in the province of Leon (Spain) burned by surface fires from a feu weeks up to 60 years before the sampling, and is compared with four zones which have not been burned. A greater similarity in floristic composition is clearly to be seen in the different phases of one same community than between different communities with the same age of regeneration. The vegetation prior to the fire conditions, therefore , is to a great extent the one which will arise after it, the process constituting a compensatory autosuccession of the regression suffered. Specific diversity increases in the first years , due mainly to an increase in species richness, showing later values more in accordance with each specific zone than to the time which has elapsed since the fire. All the communities studied are very heterogeneous, but the action of the fire can be seen as an additional generating factor of heterogeneity a few weeks after the burning. From all this, it can be deduced that these communities have been adapted to fire for a very long time and that most of the species have developed selective mechanisms to regenerate themselves quite effectively after the fires., Tarrega Reyes, Luis-Calabuig E. Effects of fire on structure, dynamics and regeneration of Quercus pyrenaica ecosystems. In: Ecologia mediterranea, tome 13 n°4, 1987. Influence of fire on the stability of mediterranean forest ecosystems. Giens (France) 23-26/03/1987. pp. 79-86.

The recovery of a Cistus shrubland after experimental treatments (cutting, burning and ploughing) was studied to determine qualitative and quantitative differences in the secondary succession. The study was carried out in three experimental plots of 100 m2 each, in which five 1 m2 sampling units were fixed and surveyed for five years, estimating cover percentage of each plant species. The data were analysed by means of affinity indexes (Sorensen and Steinhaus Indexes). The results indicated that the cover of the woody species increased progressively, but the degree of recovery depended on the treatment, as well as on the time afterwards. The number of these species remained almost constant throughout the whole period. The herbaceous species diversity was higher in the two first years in all treatments. When treatments were compared, the greatest diversity occurred after cutting. The regeneration of the community occurred by autosuccession in which the diversity decreased when the dominance of Cistus increased, unlike the general trend of the classical theories. The recovery was very quick after all three treatments, which can be interpreted as a great resilience of this ecosystem.

p. 13-19 Se estudió el proceso de regeneración de dos especies de Cistus (Cistus ladanifer y Cistus laurifolius) durante los primeros cuatro años después de cortar, quemar y arar en parcelas experimentales, en la provincia de León (NW España). En las parcelas quemadas, una germinación más rápida, seguida de una mayor tasa de mortalidad, se observó, especialmente para Cistus laurifolius. El número de plántulas tendió a estabilizarse después de un año en todas las parcelas experimentales. Durante todo el período de estudio, las parcelas quemadas mostraron un mayor número de plantas de semillero. La parcela arada presentó el número más bajo, mientras que las parcelas cortadas mantienen valores intermedios. Las diferencias en los valores de cobertura no fueron tan marcadas en las diferentes parcelas y, en el cuarto año, todavía hay una tendencia a aumentar. Ni la cubierta ni la altura de las plántulas han alcanzado los valores que tenían antes de la perturbación. Mediante la comparación de las dos especies de la misma perturbación, se encontró que los valores de cobertura y altura fueron similares, pero el número de plántulas Cistus ladanifer fue mayor. Este hecho no puede probablemente ser considerado como una consecuencia directa de perturbación, como esta diferencia también se observó anteriormente SI

Pit-fall trap catches were used to study the recolonization by the coleoptera fauna of Quercus pyrenaica ecosystems disturbed by wildfires. Two close oakwoods in León province of Spain were sampled monthly in 1990, with pit-fall traps, one burnt in June 1986 and in the other August 1989. Carabid genera such as Pterostichus and Anysodactylus increased in the four years post-fire recovered area compared to the recently burnt area and the non-burnt area. The species most affected by the environmental changes were the less generalist species, that occurred less frequently than the more adaptable species.

Understanding the effects of traditional livestock grazing abandonment on the ability of mountain grasslands to sustain multiple ecosystem functions (ecosystem multifunctionality; EMF) is crucial for implementing policies that promote grasslands conservation and the delivery of multiple ecosystem services. In this study, we evaluated the effect of short- and long-term transhumant sheep abandonment on EMF through a grazing exclusion experiment in a grassland of the Cantabrian Mountains range (NW Spain), where transhumant sheep flocks graze in summer. We considered four key ecosystem functions, derived from vegetation and soil functional indicators measured in the field: (A) biodiversity function, evaluated from total plant species evenness, diversity and richness indicators; (B) forage production function, evaluated from cover and richness of perennial and annual herbaceous species indicators; (C) carbon sequestration function, evaluated from woody species cover and soil organic carbon indicators; and (D) soil fertility function, evaluated from NH4C-N, NO3􀀀-N, P and K content in the soil. The EMF index was calculated by integrating the four standardized ecosystem functions through an averaging approach. Based on linear mixed modeling we found that grazing exclusion induced significant shifts in the considered individual ecosystem functions and also on EMF. Long-term livestock exclusion significantly hindered biodiversity and forage production functions, but enhanced the carbon sequestration function. Conversely, the soil fertility function was negatively affected by both short- and long-term grazing exclusion. Altogether, grazing exclusion significantly decreased overall EMF, especially in long-term livestock exclusion areas, while the decline in EMF in short-term exclusions with respect to grazed areas was marginally significant. The results of this study support the sustainability of traditional transhumance livestock grazing for promoting the conservation of grasslands and their ecosystem function in mountain regions. SI