Herbaceous Stratum Research Articles

GRAZING CHANGES THE SOIL-PLANT RELATIONSHIP IN THE TREE-REGENERATION STRATUM IN THE PAMPA OF SOUHTERN BRAZIL

ABSTRACT Despite being prominent in flora, the region of the Parque Estadual do Espinilho located in the Pampas of southern Brazil, where dense herbaceous stratum and isolated trees make this region suitable for livestock farming, has received little attention. The objective of the study was to analyze floristic and edaphic changes imposed by livestock farming in two areas of the park, the first under livestock grazing and the second protected from grazing (livestock-excluded) for five years. We evaluated soil physical properties of and the herbaceous aboveground biomass in order to investigate relationships with key regenerating tree species. A sampling unit of 2ha was installed in both areas, each composed of 200 subunits. Inventory of regenerating trees and herbaceous aboveground biomass, soil sampling, and soil penetration resistance tests were done in 50 subunits. The results, which were evaluated by Student’s t-test, exhibited variations between the two areas in regards to floristic and environmental factors. The abundance of the P. affinis and V. caven species and the variables of soil penetration resistance, soil bulk density, gravimetric moisture and herbaceous aboveground biomass differ significantly between the two areas. Principal coordinates analysis (PCoA) allows to infer that variables such as soil bulk density, penetration resistance and the abundance of V. caven species exhibit higher values in the area under gazing, while gravimetric moisture, aboveground biomass and abundance of P. affinis are higher in the area under livestock-excluded, showing that significant changes occur over just five years of livestock-excluded from the area.

Seasonal characterization and discrimination of savannah physiognomies in Brazil using hyperspectral metrics from Hyperion/EO-1

ABSTRACTThe seasonal characterization and discrimination of savannahs in Brazil are still challenging due to the high spatial variability of the vegetation cover and the spectral similarity between some physiognomies. As a preparatory study for future hyperspectral missions that will operate with large swath width and better signal-to-noise ratio than the current orbital sensors, we evaluated six Hyperion images acquired over the Estação Ecológica de Águas Emendadas, a protected area in central Brazil. We studied the seasonal variations in spectral response of the savannah physiognomies and tested their discrimination in the rainy and dry seasons using distinct sets of hyperspectral metrics. Floristic and structural attributes were inventoried in the field. We considered three sets of metrics in the data analysis: the reflectance of 146 Hyperion bands, 22 narrowband vegetation indices (VIs), and 24 absorption band parameters. The VIs were selected to represent vegetation structure, biochemistry, and physiology. The depth, area, width, and asymmetry of the major absorption bands centred at 680 nm (chlorophyll), 980, and 1200 nm (leaf water) and 1700, 2100, and 2300 nm (lignin-cellulose) were calculated on a per-pixel basis using the continuum removal method. Using feature selection and multiple discriminant analysis (MDA), we tested the discriminatory capability of these metrics and of their combined use for vegetation discrimination in the rainy and dry seasons. The results showed that the spectral modifications with seasonality were stronger with the savannah woodland-grassland gradient represented by decreasing tree height, basal area, tree density and biomass and by increasing canopy openness. We observed a reflectance increase in the red, red edge, and shortwave (SWIR) intervals towards the dry season. In the near-infrared, the reflectance differences between the physiognomies were smaller in the dry season than in the rainy season. From the 22 VIs, the visible atmospherically resistant index (VARI), visible green index (VIg), and normalized difference infrared index (NDII) were the most sensitive indices to water stress and vegetation cover, presenting the largest rates of changes between the rainy (March) and dry (August) seasons in shrub and grassland areas. Absorption band parameters associated with the lignin-cellulose spectral features in the SWIR increased towards the dry season with great amounts of non-photosynthetic vegetation (NPV) in the herbaceous stratum. The opposite was observed for the 680 nm chlorophyll absorption band and the 980 and 1200 nm leaf water features. In general, the number of selected metrics necessary for vegetation discrimination was lower in the dry season than in the rainy season. The best MDA-classification accuracy was obtained in the dry season using nine VIs (79.5%). The combination of different hyperspectral metrics increased the classification accuracy to 81.4% in the rainy season and to 84.2% in the dry season. This combination added a gain higher than 10% for the classification of shrub savannah, open woodland savannah and wooded savannah.

Diversidad y estructura de un pastizal en El Cerrillo, Piedras Blancas, Estado de México, México

Current knowledge of the flora and vegetation dynamics in temperate grasslands of Mexico is still scarce. In order to mitigate this deficiency, in this study the floristic composition, diversity and structure of a temperate grassland of central Mexico were evaluated. A total of 118 species, 93 genera and 40 families were recorded. The best represented families, both at the generic and specific levels are: Poaceae, Asteraceae, Fabaceae and Orchidaceae. The latter including a new species belonging to the genus Cyclopogon. The herbaceous stratum of the grassland is complex, and covers 98% of the surface. A high percentage of native species was found (20.50) and a relatively high diversity index was calculated (Simpson and Shannon=3.36). Muhlenbergia phalaroides was the dominant species and it corresponds to the highest importance value. The results suggest that these grasslands represent a sizable reservoir of species relevant for biological conservation, despite being subjected to frequent disturbances.

Daily Movement and Microhabitat Use by the Blacksmith TreefrogHypsiboas faber(Anura: Hylidae) during the Breeding Season in a Subtemperate Forest of Southern Brazil

Abstract. We studied the patterns of daily movement and habitat use of 20 males and five females of the blacksmith treefrog, Hypsiboas faber, during the breeding season in a subtemperate forest of southern Brazil. Treefrogs were tracked with externally attached thread bobbins. There were no differences between sexes in the mean straight line distance moved (HSD) or in the effective distance moved (HDM), which ranged from 0.06–3.1 m/h and 0.4–9.8 m/h, respectively). Males showed higher site fidelity and less habitat overlap than females. Despite being an arboreal species, most of the tracked individuals used the herbaceous stratum on the ground as microhabitat, which indicates a particular microhabitat use during breeding activities. Estimates of the distance moved obtained from released thread lines revealed that animals moved distances five times greater than the distances calculated by drawing a straight line between consecutive points. Therefore, our findings suggest that the sedentary behavior attribu...

Are plant communities mainly determined by anthropogenic land cover along urban riparian corridors?

Often used as a mitigation tool to landscape fragmentation, urban riparian corridors also suffered from the effects of the urban expansion. This study explored the relationships between plant riparian communities and two major environmental variables (land cover, soil characteristics) and analyzed the floristic change along an urbanization gradient. Fifteen sites were surveyed on both riverbanks of two riparian corridors characterized by contrasting water regimes in Strasbourg, North Eastern France. Data of spontaneous species abundance was collected from 180 quadrats using (i) all plant species, (ii) herbaceous stratum and (iii) ligneous stratum (bush and tree). The diversity and compositional patterns of riparian plant species were analyzed within each corridor according to three levels of urbanization (urban, suburban, peri-urban). Relationships between riparian communities, land cover and soil chemical properties (pH, nitrogen and carbon content, moisture) were established by between-class co-inertia analyses. Land cover emerged as the main factor explaining changes in riparian communities along the rural–urban gradient while soil chemical properties discriminate water stress and fluvial dynamics of the two corridors. Similar compositional patterns were found within the most urbanized sites with the establishment of ubiquitous species. The herbaceous stratum is best linked to the level of urbanization, whereas the tree stratum is primarily correlated with corridor attributes (hydrological regime, soil properties). Although riparian species and communities are mainly determined by land cover, urban riparian corridors maintain native biodiversity up to the urban center.

Environmental Harshness Decreases ant β-Diversity Between Salt Marsh and Neighboring Upland Environments

Understanding how wetland organisms interact with neighbor habitats along environmental gradients is important to recognize wetland integrity and its connectivity at landscape-level. We evaluated whether assemblage characteristics (e.g. α-diversity) of marsh-ants are associated with geographic changes in environmental conditions, and if these factors are associated with marsh-upland dissimilarity in ant species composition (β-diversity). Ant-samples were collected both in the marsh and in the neighboring upland habitat at 5-sites along the South-west Atlantic (SWA) coastline (36°S to 40°S), encompassing two-distinct biogeographic regions. Generalized Linear Models showed that at the marsh scale, ant occurrence increased with maximum temperature and Spartina densiflora cover, but decreased with total-plant cover. Ant richness increased with salinity, S. densiflora cover and marsh area; and ant α-diversity increased with S. densiflora cover and decreased with total marsh plant cover and plant height. Composition of ant assemblages differed between the marsh and the upland habitat depending on the site, and β-diversity decreased with precipitation, salinity, tidal amplitude and α-diversity of the herbaceous stratum. Then, the abundance and α-diversity of ants varied along SWA marshes in relation to changes in local environmental factors and the regional landscape. Moreover, changes in species characteristics across coastal-landscape seem to interact with environmental gradients, resulting in reduced β-diversity values with increasing environmental harshness. Thus, our results suggest that the link of geographic changes in the physical environment with the changes in species traits drives the variation in marsh-upland dissimilarity across the space.

Vegetation analyses of the South Atlantic Coastal Plain Limestone Forest association1

The South Atlantic Coastal Plain Limestone Forest is a globally imperiled (G2) association in the upper Coastal Plain of central Georgia. This calcareous forest, comprising several diverse plant communities, is floristically unique among Coastal Plain forests but its composition and structure have not been subjected to detailed study. Formal vegetation sampling and multivariate community analyses were conducted for seven sites in Bleckley, Houston, and Twiggs counties. The data generally support the current NatureServe definition of the South Atlantic Coastal Plain Limestone Forest but suggest replacing Chasmanthium sessiliflorum with Carex superata as a better representative species for the herbaceous stratum. Cluster and canonical correspondence analyses revealed two floristically defined domains (Bottomland and Upland/Slope), delimited mainly by moisture content and degree of inclination. These domains were each further divided into two subdomains and a total of 12 floristic entities defined by characteristics such as indicator species and soil variables. Communities delineated by the analyses allowed evaluation of some incongruities between several sites designated as the South Atlantic Coastal Plain Limestone Forest association by the Georgia Department of Natural Resources and provided an objective review of overall site quality. This study also resulted in the discovery of two new high-quality sites of this forest association, and these data may further serve as a baseline for identification of additional areas to target for conservation and monitoring.

Análisis palinológico de mieles y cargas de polen de <em>Apis mellifera</em> (Apidae) de la región Centro y Norte del estado de Guerrero, México

The present work is a contribution to knowledge of polen recovered from six Apis mellifera honey samples and six pollen loads samples, in order to characterize their botanical and geographical origin. Samples were collected from central and northern Guerrero -both regions of beekeeping importance during November-December 2005 and March 2006. Honeybee foraging behavior was also analyzed. Melissopalynological results showed a total of 43 pollen types belonging to 27 families; only 15 taxa of native flora were considered of importance, and their palynological descriptions are included: Cosmos sulphureus, Dyssodia papposa, Taraxacum campylodes, Tithonia tubaeformis, and Vernonia sp. (Asteraceae), Coutoubea sp. (Gentianaceae), Dalea sp. and Leucaena leucocephala (Fabaceae), Quercus sp. (Fagaceae), Miconia sp. (Melastomataceae), Pisonia sp. (Nyctaginaceae), Dodonaea viscosa and Paullinia sp. (Sapindaceae), Solanum sp. Solanaceae), and Heliocarpus donnellsmithii (Malvaceae) as well as Zea mays (Poaceae), an abundant crop. Two oligofloral and four multifloral honey samples were characterized. Diversity indexes varied from 1.7 to 2.3 in honey samples, while the pollen loads registered 1.6 to 2.1values in diversity, the evenness index in honey samples varied from 0.8 to 0.9, whereas pollen load samples registered a range from 0.6 to 0.9. Apis mellifera showed polylectic behavior; the herbaceous stratum was the most foraged, followed in importance by tree and shrub strata.

Sun-induced chlorophyll fluorescence and photochemical reflectance index improve remote-sensing gross primary production estimates under varying nutrient availability in a typical Mediterranean savanna ecosystem

Abstract. This study investigates the performances of different optical indices to estimate gross primary production (GPP) of herbaceous stratum in a Mediterranean savanna with different nitrogen (N) and phosphorous (P) availability. Sun-induced chlorophyll fluorescence yield computed at 760 nm (Fy760), scaled photochemical reflectance index (sPRI), MERIS terrestrial-chlorophyll index (MTCI) and normalized difference vegetation index (NDVI) were computed from near-surface field spectroscopy measurements collected using high spectral resolution spectrometers covering the visible near-infrared regions. GPP was measured using canopy chambers on the same locations sampled by the spectrometers. We tested whether light-use efficiency (LUE) models driven by remote-sensing quantities (RSMs) can better track changes in GPP caused by nutrient supplies compared to those driven exclusively by meteorological data (MM). Particularly, we compared the performances of different RSM formulations – relying on the use of Fy760 or sPRI as a proxy for LUE and NDVI or MTCI as a fraction of absorbed photosynthetically active radiation (fAPAR) – with those of classical MM. Results showed higher GPP in the N-fertilized experimental plots during the growing period. These differences in GPP disappeared in the drying period when senescence effects masked out potential differences due to plant N content. Consequently, although MTCI was closely related to the mean of plant N content across treatments (r2 = 0.86, p < 0.01), it was poorly related to GPP (r2 = 0.45, p < 0.05). On the contrary sPRI and Fy760 correlated well with GPP during the whole measurement period. Results revealed that the relationship between GPP and Fy760 is not unique across treatments, but it is affected by N availability. Results from a cross-validation analysis showed that MM (AICcv = 127, MEcv = 0.879) outperformed RSM (AICcv =140, MEcv = 0.8737) when soil moisture was used to constrain the seasonal dynamic of LUE. However, residual analyses demonstrated that GPP predictions with MM are inaccurate whenever no climatic variable explicitly reveals nutrient-related changes in the LUE parameter. These results suggest that RSM is a valuable means to diagnose nutrient-induced effects on the photosynthetic activity.

LA VÉGÉTATION DES INSELBERGS DU SAHEL BURKINABÈ

Les inselbergs sont des affleurements rocheux caractérisés par la précarité de leurs facteurs édaphiques et microcli- matiques. L’objectif de cette étude est de faire une étude comparative entre la végétation des inselbergs et celle des mi- lieux environnants. Les données ont été collectées dans des placeaux de 900 m2 pour la strate ligneuse et de 100 m2 pour la strate herbacée suivant un échantil- lonnage stratifié et aléatoire. Un total de 162 relevés a été réalisé. L’étude a per- mis d’inventorier 228 espèces végétales réparties dans 43 familles et 144 genres. Sur les inselbergs, 184 espèces ont été re- censées et sont réparties dans 136 genres et 36 familles. Seule l’espèce Cynanchum hastifolium a été recensée comme endé- mique stricte sur les inselbergs. Dans les milieux environnants des inselbergs, le cortège floristique est composé de 194 espèces réparties dans 40 familles et 127 genres. Le nombre moyen d’espèces par relevé est plus élevé dans les milieux environnants (23,53 ± 6,28) que dans les inselbergs (19,93 ± 4,83). La végétationdes inselbergs (719,47 ± 337,27 pieds/ ha) est moins dense que celle des milieux environnants (1 389,91 ± 674,79 pieds/ ha). D’une part, l’impact anthropique plus prononcé dans les plaines environnantes et, d’autre part, les espèces reliques et la dominance de Pterocarpus lucens sur les inselbergs traduiraient le caractère refuge des inselbergs pour certaines espèces vé- gétales. La différence entre la végétation des inselbergs et celle des milieux envi- ronnants est liée aux facteurs édaphiques et anthropiques.

Influencia de microhábitats en el desempeño de especies herbáceas en áreas de bosque maduro y secundario en la región semiárida de Brasil

<p>The conditions for plant establishment in mature forest are different from those found in disturbed areas. In dry environments, the herbaceous cover is the most important in the recolonization of deforested areas. It can, therefore, act as an ideal biological group for assessing how changes in habitat heterogeneity affect the resilience of dry forests. The aim of this research was to evaluate whether natural regeneration of the herbaceous stratum differed between areas of mature and secondary forest of Caatinga and to describe this process. The study took place in the Brazilian semiarid region during the rainy season 2011 (January to August), where fifty 1m² plots were set up, 25 allocated to the microhabitat established as “between canopies” and 25 to the microhabitat “under the canopy”. The herbaceous species selected for the study were <em>Delilia biflora</em> (Asteraceae), <em>Gomphrena vaga</em> (Amaranthaceae) and <em>Pseudabutilon spicatum</em> (Malvaceae), abundant species occurring in both areas. All individuals from the selected populations were counted, marked with sequential numbers, and the height of the stem was measured. Differences between areas, and in size and survival between microhabitats, were found only for the first two species. Fruit production was higher in the mature forest for the three species. The study concluded that: 1. The effect of the microhabitats “between canopies” and “under the canopy” in mature and secondary forest areas depends on the species considered; 2. Populations sensitive to light intensity differ in number of individuals, height and fruit production; and 3. The resilience of anthropogenic areas in semiarid environments can be characterized by the presence of spatial heterogeneity with regard to the emergence and survival of herbaceous seedlings, suggesting that the regeneration of disturbed areas may occur in patches. </p>

Impact of invasion by molasses grass (Melinis minutifloraP. Beauv.) on native species and on fires in areas of campo-cerrado in Brazil

In the Cerrado Biome of Brazil, African grasses constitute a serious problem, occurring in virtually all protected areas. Molasses grass (Melinis minutiflora P. Beauv.) accumulates more biomass than do most other species of the herbaceous stratum vegetation native to the Cerrado. In this study, our aim was to determine the impact of M. minutiflora on native vegetation, as well as (using simulations of fire traits) on the characteristics of fires, in invaded areas of the Serra do Rola-Moça State Park (Parque Estadual da Serra do Rola-Moça, PESRM), a protected area where fires are frequent, in the state of Minas Gerais, Brazil. Our main results are that M. minutiflora considerably increases the amount of biomass, becoming the main combustible plant in the campo-cerrado (grassy-woody savanna) fires in the PESRM; that the native monocot biomass is inversely correlated with the M. minutiflora biomass, suggesting suppression of the native herbaceous stratum; that eudicots are diminished by M. minutiflora, both in number of individuals and number of species; and that fires are more severe in M. minutiflora-invaded areas.

CONSUMPTION OF TREE SPECIES AND SHRUBS FOR FRUITS AND HERBACEOUS GOATS TRASHUMANCE GRAZING IN MIXTECA OAXAQUEÑA, MEXICO

<p>The purpose of this study is to determine the weight of the bite in dry matter (DM) most favorite tree and shrub species, the fruits (pods) and the herbaceous stratum as a component of the diet of goats under conditions of herding transhumance in the Mixteca Baja region and the coast of Oaxaca in order to establish the capacity of ingestion. Six animals of different age and sex of a herd consisting of 963 goats were chosen randomly. The method of direct observation of grazing was used in a whole day, once established preferences, simulated manually bite and to establish the group of values from each sample was measured, and weight. The ANOVA and Bartlett's Kolmogorov-Smirnov tests were. The means comparison test was used to determine the weight of the bite in dry matter of the various species, (HSD) Tukey (α, 0.05). Found a large variation prehensile act in the breadth and depth of the bite given to each depending on the type, shape and foliar surface woody species found that they graze on three anatomically different parts: on stem, in the area of the petiole and at the level of the central or main nerve of the leaf.</p>

Structure of arboreal and herbaceous strata in a neotropical seasonally flooded monodominant savanna of Tabebuia aurea.

Large areas in the Pantanal wetland are covered by monodominant formations, e.g. typical landscapes with local names such as "paratudal", dominated by T. aurea. Studies on structure of these formations generally include only woody strata, consequently the species richness registered is usually low due to the absence of the 'ground layer' of herbaceous and others low species. We recorded 13 species, 12 genera and 11 families for the arboreal stratum. Considering arboreal flora without the dominant (T. aurea) individuals showed great establishment in relation to the flood level between 35 - 45 cm while the individuals of the dominant species of 30 - 45 cm. The diameter distribution revealed that the population of T. aurea did not show the reverse J curve, the usual pattern for species in constant regeneration, also evidenced in inconstant Licourt quotient, indicating an episodic recruitment that could lead to future changes in structure. In the herbaceous strata we recorded 78 species, included in 62 genera and 27 families. Using plots method we sampled 46 species, 40 genera and 22 families, while in line interception we found 65 species distributed in 57 genera and 26 families. The floristic similarity of Sørensen between both methods was 59.4%, with 33 species in common, and the method of line interception was more efficient in detecting richness, with 35% more species found in the same time. According to the methods of plots and line interception applied on the woody stratum, our results gave similar detailed information on the structure of this type of savanna, and in spite of being monodominant it shows high species richness when the herbaceous stratum is taken into account. Plots and line interception methods showed similar results for the woody stratum and high species richness of the herbaceous stratum.

Selective behavior of Creole goats in response to the functional heterogeneity of native forage species in the central Monte desert, Argentina

The changes in forage availability and the physicochemical variability of plants influence the diet selection by herbivores. In this study, the foraging behavior of Creole goats was studied in terms of botanical composition of the diet, food availability and physicochemical properties of vegetation. The study was performed in a desert rangeland in the northeast (NE) Mendoza region in Argentina. Experiments with grazing goats were made in dry (winter) and wet (summer) seasons and cafeteria experiments (feeding trial) were performed during the summer. Food availability was estimated from forage species cover. Botanical composition of the goat's diet was determined by microhistological analysis of fecal samples. Morphological parts of forage species consumed by goats were sampled and analyzed to determine chemical traits (plant nutrients and secondary metabolites) in both seasons. Also, during summer, the two morphological traits of browse species stem specific density (SSD) and specific leaf area (SLA) were evaluated. In the experiments with grazing goats, diet selection was evaluated based on Ivlev's electivity index (Iˆ) and, in cafeteria experiments, preference was estimated based on the number of bites. Diet selection varied between the two seasons. Grazing goats showed differences in the patterns of diet selection related to changes in forage availability. The botanical composition of the diet had a greater (p<0.001) participation of woody species in relation to grass species in both seasons, but the herbaceous stratum was more utilized by goats during the summer according to their higher availability. Correlations between diet and availability were positive in both seasons, but not significant in summer. The models including crude protein (CP), neutral detergent fiber (NDF) and total phenols (TP) had substantial support for predicting variation in diet selection in summer and winter. In both seasons the preference increased as the concentrations of CP, NDF and TP increased, but the effect of CP was significant only in winter. Thus, goats selected supplementary food mixtures (mixed diet) and tannins were not considered dissuasive but, rather, were maintained below a certain threshold. In summer, SSD was negatively and significantly related to diet selection by grazing goats. This morphological trait allowed explaining a greater percentage of the variation in Iˆ (36%) with regard to the variation explained by the chemical variables (16%). In cafeteria experiments, in summer, the optimization of nutrient intake rate through consumption of species with low SSD values represented a best explanation for the preferences observed, whereas the hypotheses of minimization of secondary metabolites and maximization of nutrients were not able to fully explain the preferences observed in cafeteria experiments. To conclude, dietary decisions by goats in desert rangelands could be interpreted in terms of intake rate optimization and complementation of nutrients and secondary compounds, rather than by explanations involving the isolated effects of nutrient intake maximization or tannin intake minimization.

Mycorrhizal status of Cyperaceae from New Caledonian ultramafic soils: effects of phosphorus availability on arbuscular mycorrhizal colonization of Costularia comosa under field conditions

Plants from the Cyperaceae family (sedges), usually considered as non-mycorrhizal, constitute almost exclusively the herbaceous stratum of the ultramafic maquis in New Caledonia. These plants are pioneers and are important for the ecological restoration of mined areas. Costularia comosa, one of the most common sedges in this environment, was grown under field conditions on ultramafic soil, fertilized or not with phosphate and/or nitrogen. Results showed that the addition of phosphate to the soil induced a clear increase in mycorrhizal colonization of C. comosa and an increase in arbuscule abundance, reflecting the establishment of a functional mycorrhizal symbiosis. Significant positive correlations were found among mycorrhizal parameters and plant or soil phosphorus concentrations. Nitrogen fertilization did not affect mycorrhizal colonization of C. comosa. The improvement in mycorrhizal colonization by phosphate fertilization did not influence significantly nickel concentrations in the roots and shoots of plants. This study demonstrated that phosphate fertilization of ultramafic soil improved mycorrhizal colonization of C. comosa, with formation of a functional symbiosis under field conditions.

The Use of VHSR Imagery for Wildland Fire Prevention: Application to Land-Clearing Management in the South of France

Every year, the French Mediterranean area is subject to wildland fires. The prevention policy promotes the major role of forest layout, for which it is necessary to build appropriate facilities such as reducing ignition and fire propagation risks near the borders of roads and tracks, creating forest tracks to allow firefighters to move safely through the forest during a fire, creating fuel breaks in order to divide up forests and limit the propagation of fire. Land-clearing along a forest track consists in creating discontinuity between the herbaceous stratum and the tree stratum by eliminating the shrubby stratum and cutting tree crowns. It avoids fire propagation by convection, and enables firefighters to deal with the fire in safety. The main difficulty for forest officers is to identify an optimized method to select appropriate tracks to clear, because it is impossible to clear all the tracks each year. Remote sensing tools would seem to be particularly useful for obtaining the best strategic and economic overview of forest tracks at departmental scale. This theme “land-clearing evaluation method” was selected as a target application for the images derived from the new Pleiades sensors: products and services required by end users. The objective of this work is to assess the real potentiality of such Very High Spatial Resolution (VHSR) imagery for land-clearing management. The methodology used consists in image classification and spatial analysis in order to extract land-clearing quality, and also evaluation of land-clearing quality based on field questionnaires validated through interactions with firefighters and rangers. The development of this methodology and its application to QuickBird images-used as Pleiades data simulations-successfully showed that VHSR Imagery is useful for preventing fire risk. It seems to be a good perspective for providing operational mapping services to help land-clearing management.

Diferencias en cobertura y valor pastoral de la vegetación en condiciones silvopastoriles y campo natural

El trabajo tuvo como objetivo estudiar el efecto de la plantación forestal sobre la cobertura del suelo, los tipos productivos y el valor pastoral del estrato herbáceo. El estudio se realizó en tres localidades, en 18 transectas ubicadas en la entre fila, callejones cortafuego y campo natural, localizando 30 marcos de 0,25 m2 en cada una. Se determinó la cobertura de 172 especies y utilizando la clasificación de tipos productivos se estimó el valor pastoral corregido por cobertura vegetal. Las comunidades desarrolladas bajo plantaciones forestales presentaron menor cobertura vegetal. El valor pastoral de las comunidades desarrolladas en callejones cortafuego y plantaciones de Pinus taeda y Eucalyptus grandis fueron inferiores al resto de las situaciones.

First Record ofRuncinia flavida(Simon, 1881) (Araneae: Thomisidae) in Europe

The genus Runcinia Simon, 1875, as redescribed by Dippenaar-Schoeman (1980), comprises around 30 species distributed throughout the Old World (Platnick 2012). Afrotropical and Oriental region are the areas with the greatest species richness (Dippenaar-Schoeman 1983). The only species of Runcinia so far recorded in Europe is Runcinia grammica (C. L. Koch, 1837), a crab-spider from the herbaceous stratum of different types of habitats, widely distributed through southern Europe, North Africa, the Near East and Central Asia. R. grammica has also been recorded from South Africa and St Helena, although it is possible that it was introduced by marine traffic at these locations, or that these reports represent misidentifications (Dippenaar-Schoeman 1983, Dmitri Logunov, personal communication). In the Palaearctic region at least six other Runcinia species have been described: R. acuminata (Thorell, 1881), R. caudata Schenkel, 1963, and R. tarabayevi Marusik & Logunov, 1990 from Asia, R. depressa Simon, 1906 and R. flavida (Simon, 1881) from North Africa, and R. affinis Simon, 1897 from both Asia and North Africa. Although many of these species have distribution areas close to Europe, and many of them could potentially live in existing habitats from this continent (warm and mild natural or anthropogenic grassland areas, as well as dry farmed and irrigated crops; Dippenaar-Schoeman 1983, Chen & Tso 2004, Warui et al. 2005), none of these species has ever been detected in similar European habitats until now, despite the great many Palaearctic spiders that occupy wide regions divided by maritime or terrestrial barriers (Platnick 2012) and the great long-distance dispersion ability of many crab spider generalists inhabiting common habitats (Bonte et al. 2003; Bell et al. 2005). Here, we report the first European record of R. flavida (Simon 1881), previously recorded in Africa and whose nearest location to Europe is in Morocco (reported from Essaouira, Western Morocco by Simon 1909). We also discuss the implications of this discovery.

Courtship, Mating and Agonistic Behaviour inPisaura mirabilis(Clerck, 1757)*

After a short review of the literature, beginning with the discovery of the nuptial gift of the nursery-web spider Pisaura mirabilis (Clerck, 1757) in 1884 by Van Hasselt, the courtship, mating, agonistic behaviour, and peaceful coexistence of a female with two males in a planted terrarium are described (Table 1). Details of the normal mating process with a wrapped fly of different sizes are given (Figs. 3–10). Copulations occurred during both day and night. Eyesight seems to be of little importance for recognition of sexes and the gift, apart from perceiving movements. Mating variations using a freshly caught unwrapped fly (Lucilia) (Figs. 11–12), a small fly (one Drosophila), a wrapped substitute (heather blossom, Fig. 13) and even without any gift (Figs. 14–15, 23) are shown (Table 4). Males can even perform successfully with females with prey or egg sacs and on nursery webs. Agonistic behaviour, gift robbery, disturbance of mating by a rival, a threesome with one female and two males, but also peaceful male-male encounters are described and illustrated (Figs. 16–23, Table 3). Intersexual aggression and sexual cannibalism are demonstrated and discussed. The so-called “feigning death” of males (Fig. 8) is considered as an evolutionarily stable trick of the male to maintain contact with the female within the dense layer of the herbaceous stratum if she suddenly runs away after a disturbance, or simply for recovering the gift. This behaviour also occurs when two males share one gift (Fig. 22) and try to copulate with each other (Fig. 19). The benefits and disadvantages of the different kinds of gifts, evolution of the gift, its functions and the degree of cannibalism are discussed. Comparisons with the mating behaviour of related Pisauridae and Trechaleidae species using gifts and silk in courtship are made, and suggestions for further research are given.