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The establishment of oak trees is often a slow and difficult process. Hence, it is necessary to determine the characteristics that can lead to improving their regeneration. In this genus, seed size is highly variable both at the interspecific and intraspecific levels, and the effects of intrapopulation variability are not well understood, being even less so for Quercus faginea. In this study, the effects of the age of the mother tree, seed weight and the interaction between these two factors on seed germination, emergence and growth (biomass) were analysed. For this purpose, 16 trees—8 young and 8 old—were selected with the intent to cover the entire range of acorn weights produced in this population. Among the main results, it should be noted that: (1) in older trees, it is easier to find larger acorns; (2) the percentage and the speed of germination of the acorns of young trees is greater than that of old trees; (3) the percentage and the speed of seedling emergence of young trees is greater than that of old trees; and (4) cotyledon weight is the variable that most influences biomass, quite often in a positive way. Therefore, maintaining intrapopulation variability seems to be an approach that most favours the persistence of these populations.

We evaluated the ecological significance of the boundary form between two patches with contrasting vegetation (mine grassland and adjacent forest) on woody colonization and forest expansion in open-cast coal mines in Northern Spain. Woody colonization and browsing traces were measured on three mine sites, along 24 transects that were laid out perpendicular to the forest-mine boundary and classified according to their shape (concave, convex, straight). Mine sites were colonized from the close forest by woody species, whose colonization intensity depends on the boundary form. The overall colonization intensity decreased with increasing distance to the forest and differed depending on the boundary form. The more intense colonization was found in concave boundaries and the strongest decrease in convex boundaries close to the forest, whereas straight boundaries showed an intermediate colonization pattern. Concave boundaries reached higher woody cover in the basal strata of the mines than convex (up to 2 m) or straight boundaries (up to 1 m) from 11 m to the forest edge, mainly by the presence of dense patches of Cytisus scoparius (L.) Link, with a scattered overstory of Genista florida L. These shrubs might reduce the browsing intensity and act as nurse plants facilitating the establishment of Quercus petraea (Matt.) Liebl. in mine areas at greater distances from the forest edge. The forest-mine boundary form does not affect the forest vertical structure that is homogenous and does not help explain the woody colonization pattern in the mines. We conclude that edge characteristics have a strong potential to be used in the restoration of native forests based on natural processes. The implications of our results for sessile oak (Quercus petraea (Matt.) Liebl.) forest expansion along edges in fragmented Mediterranean forest landscapes were discussed.

AimsWe studied the regeneration dynamics of woodlands and abandoned old fields in a landscape dominated by Quercus suber in its lower limits for rainfall and temperature. Two hypotheses were established: (1) recruitment of Q. suber is restricted more by abiotic variations than other species adapted to more extreme Mediterranean conditions; and (2) decreases in precipitation reduce growth, but temperature positively affects growth in the leading cold edge of this species distribution area.MethodsWe selected nine sites containing forest stands and old fields with and without tree remnants, and analyzed stand structure, soil parameters and tree growth.ResultsSuccession was arrested in plots without tree remnants after cultivation abandonment. By contrast, remnant trees were accelerators of forest recovery. Tree cover played a fundamental role in Quercus recruitment throughout seed dispersal and facilitation effects that ameliorate summer drought. However, soil variables also significantly explained much of the variance observed and are important for understanding differences in regeneration. Winter and spring precipitation exerted a positive effect on tree growth, as well as temperatures during winter/spring and September.ConclusionsRegeneration dynamics are modeled by the density of tree cover in the cold and dry edge of the distribution area of Q. suber where Q. ilex is increasing in abundance. Although temperature has a positive effect on the tree growth of Q. suber, when demographic processes are considered, decreases in water availability likely play a critical role in Q. ilex recruitment. This in turn changes dominance hierarchies, especially in abandoned areas with little or no tree cover.

Producción Científica, Research Highlights: The regeneration of Quercus species is usually very difficult in many oak woodlands transformed by livestock farming. Some studies have reported that shrubs can facilitate regeneration. However, the strength of interaction may vary depending on, among other factors, the shrub species and the stress tolerance of the oak species. Moreover, further studies are necessary to clarify the relative importance of the two facilitation mechanisms in the same community. Background and Objectives: Cytisus multiflorus (L’Her.) Sweet is a predominant shrub species in the Mediterranean grazed open-oak-woodlands found in the central west of the Iberian Peninsula (bioclimatic limit) and is present with Quercus pyrenaicaWilld and Quercus ilex subsp. ballota Samp trees. Thus, we assessed the effect of these native shrubs and acorn size, and the effect of excluding large herbivores, on the seedling emergence of two contrasting co-occurring Quercus species under a bioclimatic limit. Materials and Methods: A manipulative field experiment was carried out considering four treatments as a combination of shrubs (shrub/no-shrub) and fence (fenced/open) factors. A total of twenty plots, five replicates for each treatment were available. In each plot, 20 acorns were sown: 10 acorns (5 small and 5 large) for each Quercus species. Acorn emergence was recorded during the first four years following the sowing. Results: Seedling emergence took place mostly in the spring of the first year after sowing. The presence of shrub was the main significant factor and incremented the emergence of both Q. ilex and Q. pyrenaica. The effect of the fence depended on the Quercus species considered, improving only the emergence of Q. pyrenaica. A negative effect with the small acorns was detected but only for Q. pyrenaica. In all treatments, Q. ilex emerged more than Q. pyrenaica. Conclusions: C. multiflorus had a clear facilitative effect on the seedling emergence of Q. ilex and Q. pyrenaica, which was much greater than the physical effect that acorn size and excluding large herbivores had. As such, this native shrub may have a key role in oak regeneration in Mediterranean grazed areas. Furthermore, in these areas of contact between marcescent and sclerophyllous Quercus species, Q. ilex currently emerges more than Q. pyrenaica. This could be indicative of a shift towards more xeric climatic conditions, which could lead to a change in the dominant tree species in the future. However, this change could be modulated by the effects of native shrub and large herbivores., Junta de Castilla y León - (Project SA013G19), Universidad de Salamanca - (Programa de financiación de grupos de investigación (2014/00165/001))

[EN] Aims We studied the regeneration dynamics of woodlands and abandoned old fields in a landscape dominated by Quercus suber in its lower limits of rainfall and temperature. Two hypotheses were established: (1) regeneration of Quercus species is strongly favored by the presence of tree cover; and (2) growth of Q. suber is driven by the climatic variables that represent the lower ecological limit of its leading distribution edge. Methods We selected woodlands and old fields with and without tree remnants (n = 3 per type), and analyzed stand structure, soil parameters and tree growth. Results Succession was arrested in old fields without tree remnants. By contrast, remnant trees were accelerators of forest recovery in old fields. Tree cover played a fundamental role in Quercus recruitment throughout seed dispersal and facilitation that mitigate the effects of summer drought on seedlings. Also, tree cover improved soil parameters (e.g., organic matter) that are important factors for understanding differences in regeneration. Winter/spring precipitation exerted a positive effect on tree growth, as well as temperatures during winter/spring and September. Conclusions Regeneration dynamics are modeled by the density of tree cover in the cold and dry edge of the distribution area of Q. suber where Q. ilex is increasing in abundance. Although temperature has a positive effect on the tree growth of Q. suber, when demographic processes are considered, decreases in water availability likely play a critical role in Q. ilex recruitment. This in turn changes dominance hierarchies, especially in abandoned areas with little or no tree cover., This study was funded by project SA013G19 from “Junta de Castilla y León” and by research grants awarded for final projects directed in the Master’s degree in Biology and Conservation of Biodiversity at the University of Salamanca, Spain., Publicación en abierto financiada por el Consorcio de Bibliotecas Universitarias de Castilla y León (BUCLE), con cargo al Programa Operativo 2014ES16RFOP009 FEDER 2014-2020 DE CASTILLA Y LEÓN, Actuación:20007-CL - Apoyo Consorcio BUCLE

Questions Can shrubs (Cytisus multiflorus) and large herbivore exclusion (fence) facilitate seedling survival and growth of marcescent and sclerophyllous oaks (Quercus pyrenaica vs Q. ilex subsp. ballota) under a bioclimatic limit in Mediterranean grazed areas? Location Open oak woodlands in central-western Spain (41o13’ N, 6o24’ W). Methods A two-year field experiment was conducted by planting 200 seedlings of each Quercus species under four different treatments combining the influence of nurse shrubs and fencing on Quercus seedling survival and growth. Results C. multiflorus enhanced the poor Quercus seedling survival found in the study area, at least during the first two years after planting and particularly during the first dry season. The improvement in soil organic matter under shrub canopy may have contributed to this positive effect, which was more pronounced on Q. pyrenaica seedlings. Seedling herbivory did not seem to be a limitation to survival. Increase seedling growth in both species was also very low and no growth was recorded two years after planting without shrubs. The positive shrub effect on seedling growth, especially marked in fenced areas, was more important in Q. pyrenaica in the first growing period and in Q. ilex in the second; two years after planting no different shrub effect on growth was found in either Quercus species. Seedling herbivory was a limitation to seedling growth in areas without shrubs, mainly in the case of Q. pyrenaica. Conclusions In Mediterranean grazed areas with important summer drougth and very sandy soils, shrubby Cytisus multiflorus plants have a clear facilitative effect on seedlings of ecologically-contrasted Quercus species. The facilitative effect was found in both marcescent and sclerophyllous oak seedlings, but to a different degree depending on the species considered and the variable measured (survival or growth). In terms of survival, the marcescent species was more favored by shrub cover than the sclerophyllous one, and this effect was accentuated throughout time. However, in terms of growth, although Q. pyrenaica was initially more favored by shrubs, differences between both species were attenuated after two years. Therefore, C. multiflorus can have a key role in the restoration of these oak degraded environments. This article is protected by copyright. All rights reserved.

Facilitative interactions among plants enable a species persist in stressful environments, but its use as a restoration technique of plant cover in degraded man-made ecosystems requires more accuracy. Here, a two-year field experiment was conducted to determine if native colonizer shrubs (Genista florida and Cytisus scoparius) used as nurse plants enhance Quercus petraea and Quercus pyrenaica reintroduction in reclaimed open-cast coal mines in Northern Spain. Of each tree species, 400 seedlings and 940 acorns were planted under four different treatments combining the influence of nurse shrubs and herbivory/predation upon Quercus seedlings and acorns. In each experiment, acorn emergence and seedling survival and growth were monitored. Shrubs enhanced seedling survival and growth and acorn emergence, in comparison with open spaces. Seedling survival was 90% under shrubs after the first summer. Acorn predation was a limitation, but not seedling herbivory. Seedling survival and growth were greater for Q. pyrenaica than Q. petraea, while Q. petraea showed better acorn emergence and survival of emerged acorns. The use of shrubs as nurse plants to improve environmental conditions is promising for the effective reintroduction of late successional species in reclaimed mined sites. The best results are obtained through Q. pyrenaica seedlings under shrubs. This avoids problems such as acorn predation and germination failure. The ontogenetic stage and the stress tolerance of the target species should be taken in consideration in order to increase the effectiveness of this restoration technique.

In order to reconcile conventional and emergent goals in restoration ecology, the knowledge of community assembly during succession at roadsides is crucial. With a chronosequence design, our study assesses the pathway and speed of vegetation succession on roadcuts under different specific site conditions, relating environmental factors to species cover by means of a combination of multivariate analyses and Huisman–Olff–Fresco (HOF) modeling. We want to ascertain to what extent environmental factors control primary colonization, establishment and early dynamics of vegetation on dry Mediterranean roadcuts. We found that changes in floristic composition during natural succession on roadcuts are mostly determined by the species-pool effect at different scales (landscape, regional, and local); particular site conditions of roadcuts (slope length, steepness) are also influential factors at a local scale. We also found a shift in the dispersal mode of plant species, from anemochory to zoochory, during succession on tertiary sediments and slates, and a tendency for life-form replacement, from pterophytes to hemicriptophytes, during succession on tertiary sediments. Competitive species are primarily circumscribed to tertiary sediments where succession is not so limited by environmental carrying capacity. Natural colonization is less active on granites, and hence succession is slower. Our results indicate that, in a relatively short time, vegetation communities spontaneously installed under roadcut’s environmental harshness are rich in species whether an adjacent seed source is present in remnant patches of natural vegetation. In particular, surrounding woody vegetation favors zoochory dispersion and the early arrival of late-successional species.

La restauracion de bosques autoctonos en zonas degradadas mediante procesos naturales tiene como principal objetivo la caracterizacion de micrositios adecuados para el establecimiento y desarrollo de las plantulas de arboles. En este trabajo se ha evaluado la expansion natural del bosque de Quercus petraea en un hueco minero restaurado hace 20 anos, bajo condiciones climaticas submediterraneas en el norte de Espana, en tres ambientes contrastados (bosque sin alteraciones, borde de mina y centro de mina). La densidad de plantulas y la proporcion de ramas muertas disminuyo notablemente desde el bosque hacia el centro de la mina. Los arbustos tienen un efecto positivo en el establecimiento de plantulas de Q. petraea en ambos ambientes de mina, que se incrementa a medida que el ambiente se vuelve mas estresante (desde el borde al centro de la mina), y se debe a las distintas caracteristicas estructurales de los arbustos en cada ambiente de mina. En este estudio se constata el efecto positivo de los arbustos en la colonizacion natural y establecimiento de plantulas de roble, al incrementar la heterogeneidad en las condiciones micro-ambientales en las minas restauradas. Los resultados apoyan la utilizacion de arbustos autoctonos como especies ingenieras en la reconstruccion de los ecosistemas degradados de cara a impulsar el establecimiento de especies sucesionales tardias del genero Quercus.

In this study, we combined the analysis of a coenocline with Huisman–Olff–Fresco (HOF) modelling of species behaviour to describe colonization patterns of woody species on reclaimed coal wastes in northern Spain. We hypothesize that fine-scale variation in abiotic factors along the forest-grassland gradient that appears after mining restoration affects colonization pattern of woody species. To understand these factors, we analysed changes in floristic composition and abundance of the main woody colonizers according to the spatial distance from forest limit, as well as the spatial variability of some edaphic and microclimatic parameters. Our results showed how the primary coenocline extracted from DCA1 reflected a gradient in environmental conditions influencing the species composition of the woody plant communities, from the more shade, moist and dense forest on acid and rich soils to the open, dry and oligotrophic grassland. The colonization pattern of woody species is affected by fine-scale variations in abiotic factors, such as the increase in pH, P, light, and the decrease in K, N, C/N, organic matter and soil moisture, from the forest to the restored mine. Most species HOF modelled showed monotone responses with decreasing trends along the environmental gradient from forest to mine, being Quercus petraea the species clearly dominant in the forest. On the contrary, Cytisus scoparius and Genista florida colonize intensely in the mine area, reaching the maximum abundance around 15 and 10 m distance from the forest limit, respectively. We conclude that the composition of woody species in the forest is not a good predictor of the colonizing intensity, not even of the species composition in the mine area. Copyright © 2011 John Wiley & Sons, Ltd.

In arid and semi-arid ecosystems, the presence of woody neighbours affects the existence of several herbaceous species by modifying critical aspects of the environment (e.g., soil humidity, nutrient content or light availability) beneath their canopies. Herbaceous species growing in the understory of Pinus pinaster may be distinct from those in open areas due to litter fall, light interception and changes in nutrient availability. We suggest that the overall effect of woody neighbours on herbaceous layer diversity may vary with the scale focus of analysis. To examine this hypothesis, we collected data on the abundance of herbaceous species in open pineland forests of the central Iberian Peninsula (Spain) using sample quadrats of 0.5 m × 0.5 m distributed beneath, at the edge, and outside the canopy of pines in a landscape composed of dunes and plains. The results of CCA ordination revealed significant spatial segregation of herbaceous species reflecting the occurrence of pines and dunes in the landscape. ...

The characterization of suitable microsites for tree seedling establishment and growth is one of the most important tasks to achieve the restoration of native forest using natural processes in disturbed sites. For that, we assessed the natural Quercus petraea forest expansion in a 20-year-old reclaimed open-cast mine under sub-Mediterranean climate in northern Spain, monitoring seedling survival, growth, and recruitment during 5 years in three contrasting environments (undisturbed forest, mine edge, and mine center). Seedling density and proportion of dead branches decreased greatly from undisturbed forest towards the center of the mine. There was a positive effect of shrubs on Q. petraea seedling establishment in both mine environments, which increase as the environment undergoes more stress (from the mine edge to the center of the mine), and it was produced by different shrub structural features in each mine environment. Seedling survival reduction through time in three environments did not lead to a density reduction because there was a yearly recruitment of new seedlings. Seedling survival, annual growth, and height through time were greater in mine sites than in the undisturbed forest. The successful colonization patterns and positive neighbor effect of shrubs on natural seedlings establishment found in this study during the first years support the use of shrubs as ecosystem engineers to increase heterogeneity in micro-environmental conditions on reclaimed mine sites, which improves late-successional Quercus species establishment. © 2015, Springer-Verlag Berlin Heidelberg.

Communities of plants determine nonrandom spatial patterns defined by the intervention of abiotic and biotic factors acting at different spatial scales. We consider the influence of shrubs as one of the most important factors (biotic) affecting these spatial patterns at microscale. The macroclimate could be considered one of the most important factors (abiotic) at regional scale. To study the role and the floristic implications of each factor on the global patterns of herbaceous communities, we have developed a stratified sampling design that integrates both micro and macroscale on a 100 Km-long transect (east–west) in western central Spain. The results suggest that macroclimate could be one of the most important factors in determining herbaceous spatial patterns. Moreover, shrubs create a microspatial environmental heterogeneity that could alter such global climate patterns, modifying the spatial affinities established among species. This implies that environmental heterogeneity related to microhabitat could play a key role in spatial patterns at broad spatial scales, and consequently in the dynamics of the distribution and establishment of herbaceous species.

The performance of introduced species when interacting with colonising herbs and shrubs from the surrounding areas has become an important issue in plant ecology and restoration management. In this paper, we examined the influence of hydroseeding a commercial seed mixture on the revegetation of uranium mine wastes under a semi-arid Mediterranean climate in West-Central Spain. Eight dump slope sites differing two by two in revegetation treatment (hydroseeding or not) and aspect (north/south) were monitored annually during 3 years. There was a combined effect of treatment and aspect on the floristic composition during early succession. Particularly, hydroseeding increased differences in floristic composition between aspects, being the contribution of sown species to these differences small and short. Hydroseeding increased plant cover and diversity significantly only 2 years after its application on the north-facing slopes, favoured the perennial species (mainly hemicryptophytes), and had a different effect depending on the aspect favouring grasses and legumes on the north- and south-facing slopes, respectively. The species mixture was not suitable and the use of local seeds should be tested in future revegetation projects at this zone. The importance of improving natural colonisation for ecological restoration is emphasised.

Comparative plant successional studies on derelict sites are providing significant insights into vegetation dynamics to ensure the success of future revegetation projects in these areas and, in the short-term, by using a space-for-time substitution. In this paper we describe, in relation to site exposure, vegetation development on waste rock materials covered with biologically active soil media, and compare this development with that from a previous study at the same mine (CW Spain) on non-biologically modified waste rock materials. The succession under study is faster on the North slope, as expected, and does not differ significantly from the general pattern of primary revegetation, although it was characterised by its own sequence of plant species. The topsoiling of waste increases richness and diversity from the first year of revegetation, reduces the time required for recovery of a terminal stage, and highlights the influence of slope orientation on vegetation dynamics. A total of 237 plant taxa were recorded, showing one of four patterns of change: (1) ‘pioneer’, (2) ‘intermediate’, (3) ‘late coloniser’ and (4) ‘fluctuating’.

Postfire regeneration in Cytisus oromediterraneus , a Mediterranean-basin mountain matorral species, shows a wide range of possibilities and variations in sexual and asexual regeneration. Its interpretation requires basic information on the below-ground structure of parent plants as well as on the origin and development of seedlings and various ramet (sprout clump) types: rootstock, basal-branch, and lateral-root ramets. Morphology and emergence of such ramets in C. oromediterraneus is similar to that in related species but with some specific features described here in detail. In order to determine if characteristics of 1-year-old populations depended on the age of the burned parent plants, two populations were investigated: (A 7-year-old, and B 14-year-old). In the most frequent populations in our study area, i.e. those from parent populations of ca. 7 years (A): a—plant density and biomass were highly variable and positively correlated; b—frequency distribution differed significantly from normal distribution for plant weight, but not for other parameters such as diameters, perimeter, and height, in which it did, however, show asymmetry; c—perimeter was the best parameter for estimating individuals’ weight; d—there was a higher number of seedlings than ramets but their biomass was smaller; e—the size of seedlings and ramets showed wide variation. In comparison with population A (7-year-old) population B (14-year-old) showed: significantly higher density, slightly lower biomass, higher number of small individuals, mainly seedlings, and less vigorous resprouting. In general, 1 year after fire, Cytisus oromeditarraneus population density mainly depends on the germination response, while the above-ground biomass mainly depends on the vegetative response and the intensity of both of them is conditioned by parent plant age.

Species turnover and speed of primary revegetation on uranium-mining spoils are described from the CentreWest part of Spain. Four 21-yr-old successional seres differing in substrate-grain size (broken/unbroken waste) and slope orientation (North/South) are compared. Qualitative and quantitative changes in species composition and the time required for recovery of a terminal stage are analysed, using an undisturbed pasture as reference. Revegetation succession is faster on the broken waste and on the North slope. Moreover, there is a combined effect of both abiotic factors on the pattern and duration of revegetation succession. 195 plant taxa are recorded showing one of four patterns of change: (1) ‘pioneer’; (2) ‘intermediate’; (3) ‘late coloniser’; (4) ‘fluctuating’. Multivariate analysis allows us to identify species following each of these patterns on each substrate.

Cytisus multiflorus is a leguminous matorral shrub native to the NW Iberian Peninsula, where it is one of the most important species in the extension of matorral at the expense of set-aside agricultural land. Dehesas have traditionally been used for extensive livestock raising and matorral was periodically burnt, cut or pulled out. The two latter practices are now out of use. However, burning is more frequent than in the past. The effects of fire, cutting, and pulling out of C. multiflorus on its regeneration was studied in order to ascertain whether the presently increasing distribution of the species relates to fire-stimulated regeneration or to the reduction of other traditional practices. Three years after treatment two sets of parameters were determined: 1. Plant origin: seedlings and different ramet types (ramets=resprout clumps), density, weight, and biomass as well as the percentage of resprouting. 2. Seed persistence at various soil depths. The possible mechanisms of breaking dormancy and plant emergence in different years after fire were studied in other experiments. The results suggest that the regeneration mechanism in C. multiflorus is stimulated by fire, but it is not an exclusive relationship. Stimulation occurs also after other disturbances leading to the total elimination of aerial biomass. The present expansion of the species does not appear to result from the abandonment of some traditional practices, such as cutting or pulling out, but from frequent fires (resulting in aerial-biomass elimination).

Demographic changes in Cytisus balansae populations were studied during the first 10 yr after a fire, by comparing populations of different ages in which different cohorts were considered. In the study area this species constitutes a monospecific formation which undergoes periodic burning. We distinguished both new genets (seedlings or plants originating from seedlings, after the last fire) and three types of ramets (resprout clumps): rootstock ramets, basal-branch ramets and lateral-root ramets. We found that C. balansae regenerated rapidly after fire. Most seedlings, rootstock ramets and basal-branch ramets emerged in the first year after fire. Lateral-root ramets appeared mainly after 2 - 4 yr and continued to emerge in the following years. The numbers of ramets and new genets decreased with time, mainly during the first six years. Density variations between quadrats within each population also decreased. Survivorship varied between seedlings and type of ramet, and according to time of emergence. Survival curves for seedlings which emerged in the first year were concave, for rootstock ramets convex, and for the remainder of the ramets intermediate. The 10-yr-old population was dominated by rootstock ramets. Some were entirely dead but most of them had only some dead basal branches. At this age new lateral-root ramets were still emerging. The future of C. balansae populations is discussed on the basis of results obtained for old (25 - 30 yr) plants, growing in the prolonged absence of fire.

Current work relates to the primary dispersal of Cytisus multiflorus seeds: seed production, dispersal mechanisms, distribution of seed after dissemination and dormancy were investigated. The distribution of seed was recorded before collection; seed viabilaty and dormancy were assessed. The results indicate that the dispersion is assisted by an explosive dehiscence of the seed pod in that only 35% of the seed drop directly beneath the plant, the remainder falling further away, some reaching distances greater than 3 m. Dormancy index was found to be 98.9%., [es] En el presente trabajo se estudia la dispersión primaria de las semillas de Cytisus multiflorus: cuantificación de la producción, mecanismos de dispersión, distribución de las semillas tras la diseminación, y su estado de latencia. Para ello se colocaron dispositivos de recogida de las semillas debajo y alrededor de las plantas, anotando la cantidad y distancia de la calda; posteriormente eran sembradas para comprobarla viabilidad y dormición de las semillas. Los resultados indican la existencia de una dispersión por dehiscencia explosiva; solamente el 35% de las semillas caen bajo la planta, haciéndolo el resto en sus alrededores; algunas alcanzaron distancias superiores a los 3 m. El índice de dormición es de 98.9%. [fr] Dans le présent travail on étudie la dispersion primaire des graines de Cytisus multiflorus: quantification de la production, mécanismes de dispersion, distribution des graines après la dissémination et leur état de latence. Pour ce faire on a placé des dispositifs de récolte des graines au dessous et autour des plantes, enregistrant la quantité et la distance de la chute; après elles étaient semées pour tester la viabilité et dormance des graines. Les résultats indiquent l'existence d'une dispersion par déhiscence explosive; seulement 35% des graines tombent au-dessous de la plante, et le reste dans les alentours; quelques-unes atteignent des distances supérieures à 3 m. L'index de dormition est de 98.9%.

In the absence of vegetative cover mining spoils can be subject to leaching, and to erosion by wind and water; as well as being unsightly. Rivers and streams can became clogged or polluted and adjacent areas can be contaminated. Although such wastes can be stabilized by physical means, the alternative is to cover the waste with vegetation. Revegetalion of any reclamation site will occur naturally given time, bu1 usually a more rapid development of vegetation is desirable. So, various approaches to encourage this have been tried. Plant-species selection and establishment techniques are two very important aspects to bear in mind in revegetation approaches. This paper emphasizes the role of successional studies as way to select the promising species as to test the eficacy of hydroseeding as vegetation establishment technique. Results from Mine Fe (Salamanca) reveal the mutifactorial character of natural revegetation, and to allow us to identify, the plant species associated with different revegetation stages. This information can be helpful and applied in the future management of this area. Hydroseeding has, al (he beginning, a positive effect to most of the analyzed parameters. This positive effect disappears quite soon. So, hydroseeding do not affect the natural-revegetation dynamics in Mine Fe, but the process is faster with it. En ausencia de cubierta vegetal las áreas mineras sufren procesos de lixiviación y erosión, contaminando y/o colmatando ríos, arroyos, acuíferos y zonas adyacentes, y ocasionan un fuerte impacto visual. Frente a la estabilización de los estériles por medios fisicos, la alternativa es cubrirlos con vegetación. La revegetación natural de escombreras mineras es un proceso muy lento. Puesto que se desea un desarrollo más rápido de la vegetación se han emprendido diversas iniciativas de revegetación. Al acometer la revegetación de escombreras mineras, tan importante es la elección de especies como de la técnica de revegetación. El presente estudio incide en la importancia de los estudios de sucesión vegetal en lugares alterados por la minería como herramienta para seleccionar las especies recomendables, y para comprobar la eficacia de la hidrosiembra como técnica de revegetación. Los resultados obtenidos en Mina Fe (Salamanca) ponen de manifiesto la naturaleza multifactorial del proceso de revegetación, y permiten clasificar las especies vegetales, en función de su capacidad colonizadora, lo que será de gran utilidad para futuros proyectos de revegetación en la zona. La hidrosiembra, aplicada en algunas escombreras de la mina de uranio, tiene un efecto positivo, en un principio, sobre la mayoría de los aspectos estudiados, que, sin embargo, desaparece relativamente pronto. Esto es debido a que las especies introducidas aloctonas no prosperan más allá de la primavera siguiente a su aplicación. Parece que la hidrosiembra no interfiere en la dinámica de revegetación natural de esta zona, aunque sí acelera el proceso.