Time filter

Source Type

Jaramillo-Correa J.P.,Research Center Forestal | Jaramillo-Correa J.P.,National Autonomous University of Mexico | Grivet D.,Research Center Forestal | Terrab A.,University of Vienna | And 8 more authors.
Molecular Ecology | Year: 2010

The Strait of Gibraltar (SG) is reputed for being both a bridge and a geographic barrier to biological exchanges between Europe and Africa. Major genetic breaks associated with this strait have been identified in various taxa, but it is unknown whether these disjunctions have been produced simultaneously or by independent biogeographic processes. Here, the genetic structure of five conifers distributed on both sides of the SG was investigated using mitochondrial (nad1 b/c, nad5-1, nad5-4 and nad7-1) and chloroplast (Pt1254, Pt15169, Pt30204, Pt36480, Pt71936 and Pt87268) DNA markers. The distribution of genetic variation was partially congruent between types of markers within the same species. Across taxa, there was a significant overlapping between the SG and the genetic breaks detected, especially for the four Tertiary species surveyed (Abies pinsapo complex, Pinus nigra, Pinus pinaster and Taxus baccata). For most of these taxa, the divergence of populations across the SG could date back to long before the Pleistocene glaciations. However, their strongly different cpDNA GST and RST values point out that they have had dissimilar population histories, which might include contrasting amounts of pollen-driven gene flow since their initial establishment in the region. The fifth species, Pinus halepensis, was genetically depauperated and homogenous on both sides of the SG. A further analysis of nuclear DNA sequences with coalescent-based isolation with migration models suggests a Pleistocene divergence of P. halepensis populations across the SG, which is in sharp contrast with the pre-Pleistocene divergence dates obtained for P. pinaster. Altogether, these results indicate that the genetic breaks observed across this putative biogeographical barrier have been produced by independent evolutionary processes related to the biological history of each individual species instead of a common vicariant phenomenon. © 2010 Blackwell Publishing Ltd.


Canestrari D.,University of Granada | Vera R.,University of Valladolid | Chiarati E.,University of Valladolid | Marcos J.M.,University of Valladolid | And 3 more authors.
Behavioral Ecology | Year: 2010

False feeding, where individuals refrain from delivering a food item to a begging dependent young, has been described in several cooperative bird and mammal species, but its function is still unclear. False feeding has been suggested to represent either a deceptive tactic of helpers aimed at showing off provisioning behavior to the rest of the group without paying the costs or a normal provisioning behavior of caregivers mediated by the trade-off between the hunger of the young and caregivers' own conditions. Here, we employed an experimental approach to test whether false feeding in cooperatively breeding carrion crows responds plastically to variations of chicks' and caregivers' needs. In 4 different treatments, we manipulated the hunger of the brood and the conditions of group members by 1) experimentally feeding the chicks, 2) food-supplementing group members during the breeding season or 3) throughout the whole year, and 4) clipping 2 primary feathers from each wing of some individuals to increase the costs of flight. Breeders increased false feeding when the brood was food supplemented (treatment 1) and after their wings were clipped (treatment 4), whereas helpers did not change their false-feeding behavior in response to these treatments. Conversely, helpers decreased false feeding when food was supplemented year-round (treatment 3), whereas fed breeders did not show any significant difference compared with controls. These results indicate that a trade-off between chicks' needs (current reproduction) and caregivers' conditions (future reproduction) modulates the occurrence of false feeding, determining different responses in different group members.


Ruiz-Peinado R.,Sistemas de Gestion | Ruiz-Peinado R.,Sustainable Forest Management Research Institute | Moreno G.,University of Extremadura | Juarez E.,University of Extremadura | And 4 more authors.
Journal of Arid Environments | Year: 2013

Shrubs play an important role in water-limited agro-silvo-pastoral systems by providing shelter and forage for livestock, for erosion control, to maintain biodiversity, diversifying the landscape, and above all, facilitating the regeneration of trees. Furthermore, the carbon sink capacity of shrubs could also help to mitigate the effects of climate change since they constitute a high proportion of total plant biomass. The contribution of two common extensive native shrub species (Cistus ladanifer L. and Retama sphaerocarpa (L.) Boiss.) to the carbon pool of Iberian dehesas (Mediterranean agro-silvo-pastoral systems) is analyzed through biomass models developed at both individual (biovolume depending) and community level (height and cover depending).The total amount of carbon stored in these shrubs, including above- and belowground biomass, ranges from 1.8 to 11.2 Mg C ha-1 (mean 6.8 Mg C ha-1) for communities of C. ladanifer and from 2.6 to 8.6 Mg C ha-1 (mean 4.5 Mg C ha-1) for R. sphaerocarpa. These quantities account for over 20-30% of the total plant biomass in the system. The potential for carbon sequestration of these shrubs in the studied system ranges 0.10-1.32 Mg C ha-1 year-1 and 0.25-1.25 Mg C ha-1 year-1 for the C. ladanifer and R. sphaerocarpa communities' respectively. © 2012 Elsevier Ltd.


Condes S.,Technical University of Madrid | Del Rio M.,Sistemas de Gestion | Del Rio M.,Sustainable Forest Management Research Institute | Sterba H.,University of Natural Resources and Life Sciences, Vienna
Forest Ecology and Management | Year: 2013

Despite the increasing relevance of mixed stands due to their potential benefits; little information is available with regard to the effect of mixtures on yield in forest systems. Hence, it is necessary to study inter-specific relationships, and the resulting yield in mixed stands, which may vary with stand development, site or stand density, etc. In Spain, the province of Navarra is considered one of the biodiversity reservoirs; however, mixed forests occupy only a small area, probably as a consequence of management plans, in which there is an excessive focus on the productivity aspect, favoring the presence of pure stands of the most marketable species. The aim of this paper is to study how growth efficiencies of beech (Fagus sylvatica) and pine (Pinus sylvestris) are modified by the admixture of the other species and to determine whether stand density modifies interspecific relationships and to what extent. Two models were fitted from Spanish National Forest Inventory data, for P. sylvestris and F. sylvatica respectively, which relate the growth efficiency of the species, i.e. the volume increment of the species divided by the species proportion by area, with dominant height, quadratic mean diameter, stocking degree, and the species proportions by area of each species. Growth efficiency of pine increased with the admixture of beech, decreasing this positive effect when stocking degree increased. However, the positive effect of pine admixture on beech growth was greater at higher stocking degrees. Growth efficiency of beech was also dependent on stand dominant height, resulting in a net negative mixing effect when stand dominant heights and stocking degrees were simultaneously low. There is a relatively large range of species proportions and stocking degrees which results in transgressive overyielding: higher volume increments in mixed stands than that of the most productive pure pine stands. We concluded that stocking degree is a key factor in between-species interactions, being the effects of mixing not always greater at higher stand densities, but it depends on species composition. © 2012 Elsevier B.V.


Hernandez-Rodriguez M.,Sustainable Forest Management Research Institute | Oria-de-Rueda J.A.,Sustainable Forest Management Research Institute | Oria-de-Rueda J.A.,University of Valladolid | Pando V.,Sustainable Forest Management Research Institute | And 3 more authors.
Forest Ecology and Management | Year: 2015

Mediterranean Cistus ladanifer scrublands can provide an important fungal production, often in high demand. However, due to the pyrophytic characteristics of this species, forest fires are the main threat to these ecosystems. The aim of the study is to analyze the effects of different fuel reduction treatments on C. ladanifer scrublands on production and diversity of fungal communities in order to enhance mushroom production and diversity and prevent forest fires. Sporocarp sampling was carried out on a weekly basis during autumnal production periods between 2010 and 2013. Twenty-seven plots (100m2) were established in scrublands of different age and origin: (a) a middle-age scrubland (8years old) whose origin was a forest fire, (b) a middle-age scrubland (8years old) whose origin was the total clearing of the previous stand, and (c) a senescent scrubland (20years old). Considered fuel reduction treatments were total clearing, 50% clearing and controlled burning. All the sporocarps were identified and fresh and dry weighed. A total of 63,436 sporocarps belonging to 157 taxa within 64 genera were collected during the four years' sampling. Higher total fungal fresh weight production was found in middle-aged compared with senescent scrublands. After the 50% clearing, production, diversity and species composition of fungal communities were very similar to the control plots in which no treatment was performed. It seemed to be the most appropriate treatment for the production of edible species, especially Boletus edulis and this treatment may also reduce fire intensity and severity. Furthermore, total clearing favors the fructification of new species, especially saprotrophic ones. Therefore, in this study, the rejuvenation of senescent scrublands and the alternation of different fuel reduction treatments in middle-aged stands seemed to be the best management guidelines for the sustainable management of this resource. © 2015 Elsevier B.V.


Canestrari D.,University of Oviedo | Vila M.,University of La Coruña | Marcos J.M.,University of Valladolid | Baglione V.,University of Valladolid | Baglione V.,Sustainable Forest Management Research Institute
Behavioral Ecology and Sociobiology | Year: 2012

In cooperatively breeding species, parents should bias offspring sex ratio towards the philopatric sex to obtain new helpers (helper repayment hypothesis). However, philopatric offspring might increase within-group competition for resources (local resource competition hypothesis), diluting the benefits of helper acquisition. Furthermore, benefits of offspring sex bias on parents' fitness may depend on different costs of production and/or different breeding opportunities of sons and daughters. Because of these counteracting factors, strategies of offspring sex allocation in cooperative species are often difficult to investigate. In carrion crows Corvus corone corone in northern Spain, sons are more philopatric and more helpful at the nest than daughters, which disperse earlier and have higher chances to find a breeding vacancy. Consistent with the helper repayment hypothesis, we found that crows fledged more sons in groups short of subordinate males than in groups with sufficient helper contingent, where daughters were preferred. Crow females also proved able to bias primary sex ratio, allocating offspring sex along the hatching sequence in a way that provided the highest fledging probability to sons in the first breeding attempt and to daughters in the following ones. The higher cost of producing male offspring may explain this pattern, with breeding females shifting to the cheapest sex (female) as a response to the costs generated by previous reproductive attempts. Our results suggest complex adjustments of offspring sex ratio that allowed crows to maximize the value of daughters and sons. © 2012 Springer-Verlag.


Rodriguez-Garcia E.,University of Valladolid | Rodriguez-Garcia E.,Sustainable Forest Management Research Institute | Ordonez C.,University of Valladolid | Ordonez C.,Sustainable Forest Management Research Institute | And 2 more authors.
Annals of Forest Science | Year: 2011

Introduction: Shrubs are recognized as important tree regeneration niches. In this study, we experimentally analysed the effects of shrub presence, canopy cover (closed cover and open cover-gaps), and seedling size on Pinus pinaster growth. Objective: We expected that (1) seedling-shrub interaction would depend on seedling size and would shift from positive to negative with increasing size; (2) overstorey canopy would affect seedling-shrub interaction, with stronger and positive interactions in gaps, and (3) microsite factors would be affected by vegetation. Social status and plant size appeared to determine the post-shrub-treatment growth response. Results: The effect of shrub on seedling growth varied with the canopy cover. Under closed canopy, there was a shift from a positive net effect on smaller seedlings to a negative net effect on mid-size seedlings, and then back to a positive net effect on larger seedling response. Under open canopy, a negative net effect was observed, with no change in the sign of the interaction as seedling size increased. Micro environmental conditions varied in relation to overstorey and understorey vegetation, while soil conditions varied in relation to overstorey. The seedling-shrub interaction had both positive and negative net effects, which could help define the natural regeneration dynamic of P. pinaster. © INRA and Springer Science+Business Media B.V. 2011.


Rodriguez-Garcia E.,University of Valladolid | Rodriguez-Garcia E.,Sustainable Forest Management Research Institute | Bravo F.,University of Valladolid | Bravo F.,Sustainable Forest Management Research Institute | Spies T.A.,U.S. Department of Agriculture
Forest Ecology and Management | Year: 2011

Seedling emergence, survival and early growth of the Mediterranean conifer P. pinaster were studied under closed canopy and open canopy (gaps) cover conditions in a Mediterranean forest of central Spain during two consecutive years (March 2008 to January 2010). Our main objective was to understand how overstorey structure, shrubs and soil properties influence recruitment in this species. Natural emergence and seedling survival were significantly better under closed canopy cover than under open canopy during the two consecutive years of the study; survival increased as radiation decreased. Proximity to shrubs under closed canopy cover was associated with lower mortality rates as well as a positive and apparently transitive effect on early growth. Amelioration of microclimatic conditions is hypothesized as the primary facilitation agent of those observed. Younger seedlings established during the spring of 2008 experienced higher mortality rates than older seedlings established before 2008, and soil properties affected seedling survival significantly. Water stress during summer appeared to be the main cause of seedling mortality in both years. Our study suggests that seedlings of shade-intolerant species may require overstorey cover to establish successfully, and that positive plant-plant interactions in forest communities may be more important than expected in the milder conditions provided by overstorey canopy cover. © 2011 Elsevier B.V.


Rodriguez-Garcia E.,University of Valladolid | Gratzer G.,Sustainable Forest Management Research Institute | Bravo F.,University of Natural Resources and Life Sciences, Vienna
Annals of Forest Science | Year: 2011

Background: How environmental factors affect forest regeneration is relevant for systems that depend partially or fully on natural regeneration. Methods:P. pinaster post-disturbance regeneration and its relationship to environmental factors was studied in five P. pinaster forest populations of central Spain. We expected that: 1) different harvesting methods or wildfire would promote natural regeneration in all populations, but with local and regional variations,or 2) alternatively, different site-dependent stand factors would affect natural regeneration, although generalized climate effects would be seen. Analysis of variance and multivariate analysis were used to test differences, to classify ecological variations, and to search for the most important factors affecting regeneration. Results:The results suggest that the recovery of P. pinaster forest in burnt stands, and stand replacement in harvested stands, can be achieved soon after disturbance if climatic conditions and other local-site factors (e.g., soil and overstory structure in harvested stands, cone bank in burnt stands) make the stand suitable for natural regeneration. Heterogeneous regeneration can be expected in all cases. The time of precipitation strongly influenced seedling density and successive regeneration development stages. Conclusion: Edaphic properties, combined with water availability from precipitation, can seriously limit the natural establishment of P. pinaster in xeric systems or during years of intense drought. Although many factors contribute to high variability, natural regeneration has been very effective (successful) in P. pinaster forests, which contributes to the generalization that natural regeneration is a viable forestry option in many forest types. © INRA and Springer Science+Business Media B.V. 2011.


Canestrari D.,University of Valladolid | Marcos J.M.,University of Valladolid | Baglione V.,University of Valladolid | Baglione V.,Sustainable Forest Management Research Institute
Journal of Evolutionary Biology | Year: 2011

Life history theory predicts that mothers should trade off current and future reproductive attempts to maximize lifetime fitness. When breeding conditions are favourable, mothers may either increase investment in the eggs to improve the quality of the offspring or save resources for future reproduction as the good raising environment is likely to compensate for a 'bad start'. In cooperatively breeding birds, the presence of helpers improves breeding conditions so that mothers may vary the number, size and quality of the eggs in response to the composition of the group. Here, we show that in cooperatively breeding carrion crows Corvus corone corone, where nonbreeding males are more philopatric and more helpful at the nest than females, breeding females decreased egg size as the number of subordinate males in the group increased. However, despite the smaller investment in egg size, fledglings' weight increased in groups with more male subordinates, improving post-fledging survival and indicating that helpers fully compensated for the initial 'bad start'. These results highlight a 'hidden effect' of helpers that bears profound implications for understanding the ultimate function of helping. © 2011 The Authors. Journal of Evolutionary Biology © 2011 European Society For Evolutionary Biology.

Loading Sustainable Forest Management Research Institute collaborators
Loading Sustainable Forest Management Research Institute collaborators