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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.

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.

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.