Architecture and functional traits of semi-arid shrub species in Cabo de Gata Natural Park, SE Spain

16 páginas[FR] Les caractéristiques architecturales basiques de 45 arbustes de12 familles sont décrites dans un matorral semi-aride méditerranéen à Cabo de Gata (SE de l'Espagne). Six différents modèles architecturaux de croissance de plantes sont décrits :Scarrone, Rauh, Holttum, Leeuwenberg, Champagnat et Corner.Le modèle de Tomlinson a été considéré comme une varianteà répétition basitone des modèles de Rauh, Corner, Leeuwenberg et Holttum. La variation sympodiale du modèle de Scarrone a été trouvée comme étant la plus commune dans la zone étudiée. Les caractères fonctionnels comme la hauteur de la plante, la croissance annuelle et la surface de recouvrement de la plante ont été corrélés avec les modéles architecturaux.Ainsi, des petits arbustes de taille inférieure à 0,6 m, avec une faible croissance annuelle (0,1-0,25 m) et une petite surface de recouvrement (0,5-1 m2), ont plutôt présenté un modèle de croissance sympodique, une ramification dichasiale acrotone et des inflorescences terminales. Inversement, les grands arbustes d'une hauteur de 1-3 m, présentant une large surface de recouvrement (1-3 m2), une forte croissance de rameaux latéraux (> 0,25 m) ont montré un modèle de croissance déterminé portant des inflorescences latérales. Le premier de ces deux groupes comportent des espèces qui se développent suivant la variante sympodiale du modèle de Scarrone, tandis que le second groupe contient des espèces obéissant au modèlede Rauh et incluant des arbustes épineux des communautés climaxiques.[EN] The basic architectural features of 45 shrub species representing 12 families are described from a Mediterranean semi-arid shrubland in the location of Cabo de Gata (SE Spain). Six different architectural models were recognized: Scarrone, Rauh,Holttum, Leeuwenberg, Champagnat and Corner. The Tomlinson model was recognized as a variation with basitonic repetition of the Rauh, Corner, Leeuwenberg and Holttum models. The sympodic variant of the Scarrone model was the mostcommon in our study area. Functional traits such as plant height, lateral spread and plant coverage were correlated with the architectural models. Small shrubs up to 0.6 m height with reduced lateral spread (0.1-0.25 m) and plant coverage (0.5-1 m2) were likely to have sympodic growth patterns, acrotonic dichasial branching and terminal inflorescences. Inversely,large shrubs up to 1-3 m in height, with large canopies (1-3 m2), and well developed lateral spread (> 0.25 m) were likely to have a determinate growth pattern with lateral inflorescences. The first group have species which grow following the sympodic variant of the Scarrone model, whereas the second group presents species following the Rauh model and includes thorny shrubs from the climax communities.Peer reviewe

Characterization of branch complexity by fractal analyses

9 páginas, 4 tablas, 3 figurasThe comparison between complexity in the sense of space occupancy (box-counting fractal dimension Dc and information dimension DI) and heterogeneity in the sense of space distribution (average evenness index J&d1; and evenness variation coefficient JCV) were investigated in mathematical fractal objects and natural branch structures. In general, increased fractal dimension was paired with low heterogeneity. Comparisons between branch architecture in Anthyllis cytisoides under different slope exposure and grazing impact revealed that branches were more complex and more homogeneously distributed for plants on northern exposures than southern, while grazing had no impact during a wet year. Developmental instability was also investigated by the statistical noise of the allometric relation between internode length and node order. In conclusion, our study demonstrated that fractal dimension of branch structure can be used to analyze the structural organization of plants, especially if we consider not only fractal dimension but also shoot distribution within the canopy (lacunarity). These indexes together with developmental instability analyses are good indicators of growth responses to the environment.Peer reviewe

Physiognomic and physiologic changes in mountain grasslands in response to environmental and anthropogenic factors

Mountain grasslands provide valuable ecosystem services for sustainable development and human wellbeing. These habitats have suffered important changes related with their physiognomic (biomass) and physiologic (greenness) properties. Some of these changes received significant attention i.e. woody encroachment, while others, like the changes in biomass and greenness of those grasslands that have not experienced woody encroachment are almost unknown. We calculated physiognomic and physiologic properties for dense grasslands not affected by woody encroachment through the Normalized Difference Vegetation Index (NDVI) and Normalized Difference Infrared Index (NDII) from Landsat-5 Thematic Mapper. Imagery taken in the late-1980s and late-2000s in the Spanish Pyrenees were analyzed with multi-temporal vectors to detect increases or decreases of biomass and greenness. To understand the source of these changes, we modeled them with anthropogenic (land use, i.e. grazing, ski resorts, and related infrastructures) and environmental factors (topographic, lithologic and climatic). Anthropogenic factors were most strongly correlated with decrease in the biomass and greenness, showing degradation patterns of the grasslands at localized patches. Nonetheless, environmental factors were most strongly correlated with positive changes in both indices, detecting a continuous pattern in the increase in biomass and greenness. In areas that had high livestock stocking rates, grasslands biomass and greenness decrease, while in areas that had low stocking rates, biomass and greenness increases. Grasslands at low elevation showing decrease in biomass and greenness were either on gentle slopes and largely affected by human activities, or on steep slopes locally affected by ski resorts. In areas that have been disturbed by anthropogenic factors, the increase of rain in early summer trigger erosion processes, enhancing the negative effect of anthropic pressure on grassland greenness and biomass. In contrast, grasslands at high elevations, on steep slopes, and those that had north or west aspects and that had an acidic lithology, with less continentality, and that received more rain, had the most increase in biomass and greenness. Those results suggest that changes in mountain grasslands, apart from woody encroachment, are deeply altering their physiology and physiognomy, pointing out direct relationships with current management practices and climate trends.This research was funded by the following research projects; Ref.:125/2010 MMAMRM (Spanish Ministry of Agriculture and Environment), CGL2011-27259 (Spanish Ministry of Economy and Competitiveness and Innovation) co-financed by the FEDER, and FW7 ENV.2009.2.1.3.2-LEDDRA (European Community). CGB was supported by the AXA Research Fund (PDOC_2011_W2) and Killam Postdoctoral Fellowship (University of Alberta (2012-2013)). F. Fillat and R. García provided interesting comments and supporting climatic information.Peer reviewe

Inferring resilience to fragmentation-induced changes in plant communities in a semi-arid Mediterranean ecosystem

Predicting the capacity of ecosystems to absorb impacts from disturbance events (resilience), including land-use intensification and landscape fragmentation, is challenging in the face of global change. Little is known about the impacts of fragmentation on ecosystem functioning from a multi-dimensional perspective (multiple traits). This study used 58 500-m linear transects to quantify changes in the functional composition and resilience of vascular plant communities in response to an increase in landscape fragmentation in 18 natural scrubland fragments embedded within a matrix of abandoned crop fields in Cabo de Gata-Níjar Natural Park, Almería, Spain. Changes in functional community composition were measured using functional diversity indices (functional richness and functional dispersion) that were based on 12 plant traits. Resilience was evaluated using the functional redundancy and response diversity from the perspective of plant dispersal, which is important, particularly, in fragmented landscapes. Scrubland fragmentation was measured using the Integral Index of Connectivity (IIC). The functional richness of the plant communities was higher in the most fragmented scrubland. Conversely, the functional dispersion (i.e., spread) of trait values among species in the functional trait space was lower at the most fragmented sites; consequently, the ecological tolerance of the vegetation to scrubland fragmentation decreased. Classifying the plant species into four functional groups indicated that fragmentation favoured an increase in functional redundancy in the 'short basal annual forbs and perennial forbs' group, most of which are species adapted to degraded soils. An assessment based on the traits associated with plant dispersal indicated that the resilience of 'woody plants ', an important component in the Mediterranean scrubland, and habitat fragmentation were negatively correlated; however, the correlation was positive in the 'short basal annual forbs and perennial forbs ' and the 'grasses' groups. © 2015 de Frutos et al.We are grateful to Beatriz Bueno, Elena Lahoz, Benjamin Komac, and Virginia Pascual for assisting with the collection of field data. We thank Luis Villar for his help in translating the biological types. María Felipe, Maite Gartzia, Bruce MacWhirter, and two referees provided critical comments and helpful suggestions on the manuscript.Peer Reviewe

Association between competition and facilitation processes and vegetation spatial patterns in alpha steppes

11 páginas, 5 figuras, 3 tablas.-- El PDF del artículo es la versión post-print.In semiarid ecosystems, the self-organized spatial patterns of plants associated with catastrophic shifts can emerge from a variety of processes. In this study, on moderate slopes where Stipa tenacissima cover was high, the self-organization of some of the typical species of semiarid Mediterranean matorral (Phlomis purpurea, Sideritis oxteosylla, Helianthemum almeriense, and Brachypodium retusum) was negatively correlated with Stipa cover. The extent of Stipa cover did not affect desert pioneer species, such as Artemisia herba-alba, Fagonia cretica, and Launaea lanifera. On pronounced slopes, the self-organizing structure of brushwood vegetation did not vary predictably with the amount of Stipa cover. We examined the competition/facilitation processes associated with self-organizing patterns in the dwarf shrub (Phl. purpurea) and the half shrub (H. almeriense). The developmental stability of H. almeriense was positively correlated with Stipa cover, which was expected because they are associated species in this seral thyme brushwood community. Indeed, facilitation processes were manifested by the developmental stability increases under the Stipa canopy, particularly on high slope areas, where Stipa is less competitive. In Phl. purpurea, negative feedback processes from competition with Stipa were manifested where Stipa cover was high and on low slopes (developmental instability increased). In general, competition with Stipa on low slopes tended to decrease plant self-organization.We gratefully acknowledge support from the Spanish CICYT (Project REN2002-04668/GLO, Efectos de la fragmentación y uso del suelo en la conservación y dinámica de las zonas esteparias Mediterráneas).Peer reviewe

Developmental Instability and Fitness in Periploca laevigata Experiencing Grazing Disturbance

10 páginas, 4 figuras, 4 tablas.We investigated the sensitivity of developmental instability measurements (leaf fluctuating asymmetry, floral radial asymmetry, and shoot translational asymmetry) to a long‐standing natural stress (grazing) in a palatable tannin‐producing shrub (Periploca laevigata Aiton). We also assessed the relationship between these measures of developmental instability and fitness components (growth and floral production). Developmental instability, measured by translational asymmetry, was the most accurate estimator of a plant’s condition and, consequently, environmental stress. Plants with less translational asymmetry grew more and produced more flowers. Plants from the medium‐grazed population were developmentally more stable, as estimated by translational and floral asymmetry, than either more heavily or more lightly grazed populations. Leaf fluctuating asymmetry was positively correlated with tannin concentration. The pattern of internode growth also responded to grazing impact. Plants under medium to heavy grazing pressure accelerated early growth and consequently escaped herbivory later in the season, i.e., at the beginning of the spring, when grazing activity was concentrated in herbaceous plants. Periploca laevigata accelerated growth and finished growing sooner than in the other grazing treatment. Thus, its annual growth was more mature and less palatable later in the season when grazers typically concentrate on shrubs. The reduction of developmental instability under medium grazing is interpreted as a direct effect of grazing and not as the release from competition.The work was realized under the Desertification Risk Assessment in Silvopastoral Mediterranean Ecosystems (DRASME) collaborative research project. DRASME is funded by the European Community under its International Cooperation with Developing Countries Program, contract number ERBIC18‐CT98‐0392. The support from this program is gratefully acknowledged. We are grateful to Dr. T. Navarro and Dr. M. Vrahnakis for critically reading the manuscript and making helpful suggestions. David Navas and Antonio Gonzalez assigned the taxonomic identification of each species, for which we are very grateful. We thank Rosa Jimenez Ortega, Antonio Parra Perez, David Navas, and Antonio Gonzalez for collaborating with us in the collection of data.Peer reviewe

Change in plant spatial patterns and diversity along the successional gradient of Mediterranean grazing ecosystems

In this study, we analyze the complexity of plant spatial patterns and diversity along a successional gradient resulting from grazing disturbance in four characteristic ecosystems of the Mediterranean region. Grazing disturbance include not only defoliation by animals, but also associated disturbances as animal trampling, soil compaction, and mineralization by deposition of urine and feces. The results show that woodland and dense matorral are more resistant to species loss than middle dense and scattered matorral, or grassland. Information fractal dimension declined as we moved from a dense to a discontinuous matorral, increasing as we moved to a more scattered matorral and a grassland. In all studied cases, the characteristic species of the natural vegetation declined in frequency and organization with grazing disturbance. Heliophyllous species and others with postrate or rosette twigs increased with grazing pressure, particularly in dense matorral. In the more degraded ecosystem, only species with well-adapted traits, e.g., buried buds or unpalatable qualities showed a clear increase with grazing. Indeed, the homogeneity of species distribution within the plant community declined monotonically with grazing impact. Conversely, the spatial organization of the characteristic plants of each community increased in the better-preserved areas, being also related to the sensitivity of the species to grazing impact. The degree of autocorrelation of plant spatial distribution at the species level and the information fractal dimension at the community level allow us to quantify the degree of degradation of natural communities and to determine the sensitivity of key species to disturbance.http://www.sciencedirect.com/science/article/B6VBS-4D2FMJK-3/1/3bd96d3eb6d9aa73038f87bb6b8c82b

Increased Soil Frost Versus Summer Drought as Drivers of Plant Biomass Responses To Reduced Precipitation: Results from A Globally-Coordinated Field Experiment

Reduced precipitation treatments often are used in field experiments to explore the effects of drought on plant productivity and species composition. However, in seasonally snow-covered regions reduced precipitation also reduces snow cover, which can increase soil frost depth, decrease minimum soil temperatures and increase soil freeze-thaw cycles. Therefore, in addition to the effects of reduced precipitation on plants via drought, freezing damage to overwintering plant tissues at or below the soil surface could further affect plant productivity and relative species abundances during the growing season. We examined the effects of both reduced rainfall (via rain-out shelters) and reduced snow cover (via snow removal) at 13 sites globally (primarily grasslands) within the framework of the International Drought Experiment, a coordinated distributed experiment. Plant cover was estimated at the species level and aboveground biomass was quantified at the functional group level. Among sites, we observed a negative correlation between the snow removal effect on minimum soil temperature and plant biomass production the next growing season. Three sites exhibited significant rain-out shelter effects on plant productivity, but there was no correlation among sites between the rain-out shelter effect on minimum soil moisture and plant biomass. There was no interaction between snow removal and rain-out shelters for plant biomass, although these two factors only exhibited significant effects simultaneously for a single site. Overall, our results reveal that reduced snowfall, when it decreases minimum soil temperatures, can be an important component of the total effect of reduced precipitation on plant productivity

Revista de Vertebrados de la Estación Biológica de Doñana

Catálogo descriptivo de los anfibios y reptiles de CubaEvolución estacional de la comunidad de aves en un robledal de Sierra NevadaComposición de la comunidad de aves en pinares del Parque Nacional de Doñana (suroeste de España).Alimentación de la pagaza piconegra (Gelochelidon nilotica) en las marismas del GuadalquivirContaminación xenobiótica del Parque Nacional de Doñana. III. Residuos de insecticidas organoclorados, bifenilos policlorados y metales pesados en ciconiformesAlimentación de la lechuza común Tyto alba en la cuenca del Duero, EspañaEstudio de una población rural de (Mus musculus L.) I. La probabilidad de captura y la estima numéricLa reproducción en Gazella dorcasIncidencia del Nemátodo parásito Skrjabingylus Leuckart, 1842 sobre el Mustela en España.Desplazamientos de ungulados silvestres a través de una zona de ecotono en Doñana.Etograma de la cabra montés (Capra pyrenaica) y comparación con otras especies.Sobre comportamiento agresivo de Triturus marmoratus en época de celoEmbarrancamiento masivo de ejemplares de tortuga lad (Dermochelys coriacea L.) en las costas de Ceuta (España, norte de África)Sobre un ejemplar melánico de Podarcis hispanica (Steindachner, 1870)Nuevos datos sobre la distribución de cuatro especies de reptiles en la provincia de Cádiz.Algunos datos sobre la nidificación de Ciconia nigra L. en sierra Morena (S. España)Observación del halcón de Eleonor (Falco eleonorae) en el centro de EspañaNueva localidad de cría del pájaro moscón (Remiz pendulinus) en la Península IbéricaRegistro de aves en el sur de BoliviaNidificación del paiño de Madeira Oceanodroma castro (Harcourt, 1851) en las Islas Canarias.Observación primaveral de Phalaropus fulicarius L. en el SO de EspañaNuevos datos sobre la presencia del nóctulo gigante Nyctalus lasiopterus (Chiroptera, vespertilionidae) en EspañaNote sur l'alimentation de Martes martes a Menorca (Baleares).Peer reviewe

Revista de Vertebrados de la Estación Biológica de Doñana

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