Person: Balaguer Núñez, Luis
Universidad Complutense de Madrid
Faculty / Institute
Now showing 1 - 10 of 14
PublicationSpatial and demographic structure of tara stands (Caesalpinia spinosa) in Peru: Influence of present and past forest management(Elsevier, 2016-10-01) Cordero, I.; Jiménez Escobar, María Dolores; Delgado Sáez, Juan Antonio; Villegas, L.; Balaguer Núñez, LuisTropical dry forests are highly endangered ecosystems that have been scarcely studied. Many species within these forests suffer regeneration problems due to unsustainable management regimes. In particular, a regeneration problem has been detected in a forest of tara (Caesalpinia spinosa), a neotropical tree of high ecological and economic value, in Atiquipa (Peru). The study of the spatial patterns and population structure of forests can help us understand their dynamics and evaluate the effects of management. In this article, we analyse the stand demographic structure, spatial distribution and patterns of plant interactions in tara forests. We evaluate whether the regeneration problem in Atiquipa is strictly local or a problem of general concern and investigate the most probable causes. Four tara stands were selected at different localities in Peru. Two stands (Andurco and Polán) had a reverse J-shaped diametric structure, typical of stable self-replacing forests, although Polán had a low number of young trees, indicating an incipient regeneration problem. The Lloque histogram was skewed (with a maximum in seedlings 61 cm), indicating over-exploitation in the past and present forest regeneration. Maguey had a low number of regenerates, with peaks in some intermediate diametric classes, which may indicate natural regeneration problems or some past management. Spatial distribution of tara trees did not depart from the null model (�random distribution), typical of trees dispersed by zoochory. Maguey was an exception, showing a regular pattern at short distances, possibly associated with past management (like selective cuttings and/or plantations). These results suggest that in most of the analysed stands the current forest management (i.e. excessive seed collection or grazing) limits tara forest regeneration. However, the only stand with a protected status presented a clear tendency toward population increase. Bivariate analyses revealed an aggregated pattern between seedlings and adult trees. Moreover, the plant-plant interaction study showed that seedlings were associated with woody vegetation. These positive associations highlight a facilitative effect that ameliorates stressful microclimatic characteristics and/or protects tara seedlings from herbivory. The results of this study support some recommendations for sustainable management, such as controlled stocking rate, limited seed collection and promotion of bush cover. PublicationRoadside Reclamation Outside the Revegetation Season: Management Options under Schedule Pressure(Wiley, 2011-01-11) Mola, Ignacio; Jiménez, María Dolores; López Jiménez, Nicolás; Casado González, Miguel Ángel; Balaguer Núñez, LuisRoadside reclamation involves standard revegetation practices that often fail under the adverse conditions imposed by subordination to the infrastructure construction schedule. We experimentally tested for seed and microsite limitations on roadslopes by assessing the effects of seed addition and habitat suitability upon plant cover and species richness. The relative contributions of topsoil seed bank, seed rain, and hydroseeding with standard or native seed mixtures were analyzed in relation to soil texture, fertility, and stability. In order to increase applicability, this research was fitted into the actual construction design and schedule of a highway in central Spain, which resulted in topsoil of varying quality, steep roadcuts and embankments (34◦), and out-of-season hydroseedings. During the first 2 years following roadslope construction, there was an uneven but sustained increase in plant cover and species richness. Topsoil spread on embankments led to greater plant cover in a shorter time and to lower sedimentation rates at slope bases. The topsoil seed bank was extremely poor. Hydroseeding invariably failed, regardless of seed mixture and roadslope type. The seed rain provided seven times more seeds than hydroseedings, and was correlated with the distance to vegetation patches. Recruitment, however, was limited by microsite suitability, as the initial soil content in nitrate, total nitrogen, and organic matter explained up to 80% of variation in plant cover. In conclusion, when revegetation was performed outside the optimal season due to schedule constraints, measures aimed at overcoming microsite limitation were more cost-effective and enhanced roadside carrying capacity for local species. PublicationPerspective: The historical reference in restoration ecology: Re-defining a cornerstone concept(Elsevier, 2014) Balaguer Núñez, Luis; Escudero Alcántara, Adrián; Martín Duque, José Francisco; Mola, Ignacio; Aronson, JamesEcological restoration aims to revitalize ecosystem integrity and functionality following severe damage or degradation. Often, however, efforts are hampered by an incomplete or flawed concept of historical ‘reference’ used when choosing or constructing a target ecosystem or landscape to restore ‘to’. This problem may stem from a culturally-skewed interpretation of history or from misunderstanding or underestimation of the role that humans have played in a given ecosystem’s historical development and dynamics. While strongly confirming the importance of the reference concept in restoration ecology, we argue for the need to refine it, and to broaden the ways it can be conceived, developed, and applied. Firstly, the historical reference system informing a given restoration project should be grounded in both latent and active ‘ecological memories’, encoded and stored across relevant geographical and temporal scales. Further, the generally neglected geomorphic component of reference-building should also be addressed, as well as the contributions of human cultures to current ecosystem and landscape condition. Thirdly, ecosystems are historically contingent and multi-layered. Pre-versus post-disturbance comparisons are insufficient. Instead, restoration scenarios should be seen as tapestries of multiple and successive states. In sum, a well-conceived reference model helps promote and ensure the recovery and subsequent maintenance of historical continuity, i.e., the reestablishment of an impaired ecosystem to its historic ecological trajectory. We use case studies from pain and Peru to illustrate how this approach can provide better goalposts and benchmarks, and therefore better guide the planning, implementation, and evaluation of effective restoration projects. PublicationSoil functionality at the roadside: Zooming in on a microarthropod community in an anthropogenic soil(Elsevier, 2013-08-26) Magro Ruiz, Sandra; Gutiérrez López, Mónica; Casado González, Miguel Ángel; Jiménez Escobar, María Dolores; Trigo Aza, María Dolores; Mola, Ignacio; Balaguer Núñez, LuisEarth movements for road construction give rise to nutrient-poor anthrosols. Early onset of soil processes in these environments has been reported on the basis of plant cover establishment. Evidences of full soil functionality, however, would reveal the emergence of a self-sustainable ecosystem on these manmade substrates. The aims of the present study involved (1) assessing soil functionality on six-year-old road embankments by means of the QBS index, based on microarthropod communities (2) elucidating soil properties responsible for the composition of soil microartrhopod communities, and (3) exploring the practical implications of soil quality for road embankment management. Road embankments were functional with QBS values comparable to those found in natural systems (>100). Soil quality in these environments depended on soil organic carbon dynamics. Among the 36 arthropod groups found, Acari and Collembola dominated the soil community. Variation in microarthropod community composition was best explained by higher abundances of Brachypilina (Oribatida, Acari) and Symphypleona (Collembola). These trends in soil community structure were intimately linked to soil organic carbon content, clay content and humidity. Given its relevance, the acknowledgment of the early functionality attained by these roadside anthrosols should lead to the revision of current protocols for roadslope monitoring and management. PublicationSoil development at the roadside: a case study of a novel ecosystem(Wiley, 2011-11-23) Jiménez Escobar, María Dolores; Ruiz-Capillas, P.; Mola, Ignacio; Pérez Corona, Esther; Casado González, Miguel Ángel; Balaguer Núñez, LuisOver the last few decades, road construction has increased dramatically, and new surfaces have appeared in most landscapes. Standard roadside reclamation practices often fail, because vegetation establishment appears to be limited by microsite availability. We considered soil properties as a key factor driving vegetation establishment on roadslopes over time. We address the following questions: (i) Are soil features conditioned by type of roadslope, position thereupon or applied hydroseeding? (ii) Is there any evidence of soil development at the roadside four years after road construction? (iii) Do mutual interactions exist between soil features and vegetation cover? We designed an experimental set-up on a highway in Central Spain (Madrid). We selected 15 roadslopes (nine roadcuts and six embankments) with three hydroseeding treatments (commercial, alternative and untreated). Four years after the road construction, we considered three roadslope positions (top, middle and bottom) to take into account the geomorphological gradient.We monitored soil features and vegetation cover over 4 years after the road construction. Soil chemical differences were found between roadslope types, mainly resulted from topsoil spreading on embankments and the weathering of the newly exposed materials on roadcuts. Applied amendments do not affect soil fertility or vegetation cover. In the course of time, vegetation establishment and geomorphological gradients operate differentially on roadcuts and embankments. Accordingly, cycling back of organic compounds or geomorphological processes differs between roadslopes types. Restoration efforts should be directed to guarantee key ecological processes and support soil formation. PublicationErratum to: Field patterns of temporal variations in the light environment within the crowns of a Mediterranean evergreen tree (Olea europaea)(Springer-Verlag, 2016) Ventre-Lespiaucq, Agustina B.; Escribano Rocafort, Adrián Gaspar; Delgado Sáez, Juan Antonio; Jiménez Escobar, María Dolores; Rubio de Casas, Rafael; Granado Yela, Carlos; Balaguer Núñez, Luis PublicationSink strength manipulation in branches of a Mediterranean woody plant suggests sink-driven allocation of biomass in fruits but not of nutrients in seeds(Springer, 2016-07-25) Catalán, Pablo; Delgado Sáez, Juan Antonio; Jiménez Escobar, María Dolores; Balaguer Núñez, LuisThe relative autonomy of branches within an individual plant may favor different resource allocation responses after reproductive losses. The assessment of these reproductive strategies at the branch level before their integration at the plant level would provide more insight into how plants deal with reproductive losses. Here, we present a field experiment to assess changes in the allocation strategies at the branch level after sink strength manipulation in a Mediterranean woody plant (Cistus ladanifer). We applied three levels of removal of developing fruits (75, 25 and 0 %) on branches of the same plants, and measured their effects on resource allocation (biomass, nitrogen and phosphorus) and seed production after controlling for the effects of branch diameter and leaf weight per branch. Our results suggest that after experimental fruit thinning, C. ladanifer branches presented a sink-driven allocation of biomass to fruits but this was not the case for the allocation of nutrients to seeds, which could be driven by competition with leaf biomass. Reductions in biomass per fruit resulted in a reduction in seed output since the average weight per seed remained constant. From these results, it could be suggested that an heterogeneous distribution of fruit losses among the branches within a crown would produce a higher impact on reproductive output than a more equitable distribution. PublicationField patterns of temporal variations in the light environment within the crowns of a Mediterranean evergreen tree (Olea europaea)(Springer-Verlag, 2016-06) Ventre-Lespiaucq, Agustina B.; Escribano Rocafort, Adrián Gaspar; Delgado Sáez, Juan Antonio; Jiménez Escobar, María Dolores; Rubio de Casas, Rafael; Granado Yela, Carlos; Balaguer Núñez, LuisThe light environment within a tree crown can be characterized by specific variation patterns arising from the structural features of the crown. Within-crown light variation patterns can be important for plant productivity, but this has yet to be assessed in natural settings. The spatio-temporal variations of direct and diffuse photosynthetic photon flux density (PPFD), their proportions and sunfleck frequency within the crowns of isolated adult wild olive trees (Olea europaea L.) were investigated. Trees growing in contrasting Mediterranean conditions (continental vs. coastal) at the same latitude were compared. Instantaneous diffuse and total PPFD were measured with sunshine sensors in three crown layers (outer-, middle- and inner-crown) in the south-facing part of the crown, at two points of the diurnal (mid-morning and midday) and seasonal (summer and winter) cycles. Direct PPFD and the proportion of direct to total PPFD vary diurnally within the crown as a result of an increase in sunfleck requency during midday and in self-shading during mid-morning, in both summer and winter conditions. Conversely, the lack of seasonal variation in the three light attributes is better explained by a greater average crown transmittance in winter conditions. The interplay between crown architecture heterogeneity and varying solar position renders identifiable patterns of temporal variations in the light environment within tree crowns. These patterns suggest that trees can benefit from the light heterogeneity typical of Mediterranean environments by developing conservative architectural layouts. PublicationSimplifying data acquisition in plant canopies- Measurements of leaf angles with a cell phone(Wiley, 2014-02) Escribano-Rocafort, Adrián G.; Ventre-Lespiaucq, Agustina B.; Granado Yela, Carlos; López-Pintor Alcón, Antonio; Delgado Sáez, Juan Antonio; Muñoz, Vicente; Dorado, Gabriel A.; Balaguer Núñez, Luis1.Canopies are complex multilayered structures comprising individual plant crowns exposing a multifaceted surface area to sunlight. Foliage arrangement and properties are the main mediators of canopy functions. Theleaves act as light traps whose exposure to sunlight varies with time of the day, date and latitude in a trade-off between photosynthetic light harvesting and excessive or photoinhibitory light avoidance. To date, ecological research based upon leaf sampling has been limited by the available technology, with which data acquisition becomes labour intensive and time-consuming, given the overwhelming number of leaves involved. 2. In the present study, our goal involved developing a tool capable of measuring a sufficient number of leaves to enable analysis of leaf populations, tree crowns and canopies. We specifically tested whether a cell phone working as a 3D pointer could yield reliable, repeatable and valid leaf angle measurements with a simple gesture. We eval-uated the accuracy of this method under controlled conditions, using a 3D digitizer, and we compared perfor-mance in the field with the methods commonly used. We presented an equation to estimate the potential proportion of the leaf exposed to direct sunlight (SAL) at any given time and compared the results with those obtained by means of a graphical method. 3.We found a strong and highly significant correlation between the graphical methods and the equation presented. The calibration process showed a strong correlation between the results derived from the two methods with a mean relative difference below 10%. The mean relative difference in calculation of instantaneous exposure was below 5%. Our device performed equally well in diverse locations, in which we characterized over 700 leaves in a single day. 4.The new method, involving the use of a cell phone, is much more effective than the traditional methods or digitizers when the goal is to scale up from leaf position to performance of leaf populations, tree crowns or canopies. Our methodology constitutes an affordable and valuable tool within which to frame a wide range of ecological hypotheses and to support canopy modelling approaches. PublicationCommunity ontogeny at the roadside: Critical life-cycle events throughout a sequential process of primary colonization(Wiley, 2014) Magro, Sandra; Jiménez Escobar, María Dolores; Casado González, Miguel Ángel; Mola, Ignacio; Arenas Escribano, Juan María; Martín Duque, José Francisco; Vazquez, Ana; Balaguer Núñez, LuisQuestions: How does the response to environmental filters change across the life cycle of pioneer plants through the early process of community assembly? Is there a threshold at any of the life-history stages during roadcut primary colonization? Location: A very steep, sun-exposed, low-fertility and low water retention roadcut in a Mediterranean continental site in Madrid, central Spain. Methods: We tracked density of individuals, plant cover, species richness and community composition throughout the sequential process of primary colonization of a newly-exposed roadcut surface. We monitored from seed arrival to seedling emergence, seedling survival and plant growth across species over two growing seasons. We manipulated the intensity of environmental filters in 12 experimental plots (10 9 8 m) following a full-factorial design of two treatments (topsoil spreading and shallow tillage). Results: The response to environmental filter manipulation varied throughout the individual life cycle. Under an equal seed rain, the higher carrying capacity caused by topsoil spreading gave rise to the emergence of a larger number of species, which either persisted or occasionally appeared in some of the stages of the early community assembly. Further, topsoil spreading enhanced seedling survival across species, as well as subsequent plant growth. We therefore detected two life-history stages acting as thresholds in plant community assembly due to an ontogenetic niche shift across species. The first, at seedling emergence, in response to environmental cues with lasting consequences in community composition and species richness; and the second, at the transition to the adult stage in response to local resource availability, with consequences in subsequent plant growth and community cover. Conclusions: During primary colonization, ontogenetic development of pioneers was paralleled by the action of environmental filters throughout the community assembly process. On roadcuts, the confluence of both processes gives rise to a community ontogeny marked by two thresholds determining community richness and cover under Mediterranean conditions. Our findings shed light on the underlying mechanisms involved in technical solutions, such as topsoil spreading, and provide a more efficient approach to roadside restoration.