Different moments in the participatory stage of the secondary students’ abstraction of mathematical conceptions

This study provides support to the characteristics of participatory and anticipatory stages in secondary school pupils’ abstraction of mathematical conceptions. We carried out clinical task-based interviews with 71 secondary-school pupils to obtain evidence of the different constructed mathematical conceptions (Participatory Stage) and how they were used (Anticipatory Stage). We distinguish two moments in the Participatory Stage based on the coordination of information from particular cases by activity-effect reflection which, in some cases, lead to a change of focus enabling secondary-school pupils to achieve a reorganization of their knowledge. We argue that (a) the capacity of perceiving regularities in sets of particular cases is a characteristic of activity-effect reflection in the abstraction of mathematical conceptions in secondary school, and (b) the coordination of information by pupils provides opportunities for changing the attention-focus from the particular results to the structure of properties.

Extinction trends of threatened invertebrates in peninsular Spain

Using information from two recently published atlases of threatened invertebrate species in peninsular Spain, we examined the climatic, land use and geographic characteristics of the 100 km2 UTM cells with most likelihood of suffering extinctions (extinction cells), as well as the attributes of the species prone to population extinctions. Extinction cells have had significantly (1) lower precipitation values, (2) higher temperatures, (3) higher percentages of anthropic land uses or (4) higher rates of anthropization during the last 20 years than the remaining cells. Nevertheless, probable extinctions may occur under a wide range of climatic and anthropization change rates and these variables can only explain a low proportion (~5 %) of variability in the occurrence or number of extinction cells. Aquatic species seem to suffer higher local extinction rates than terrestrial species. Interestingly, many invertebrate species with approximately 25 or less occurrence cells are on a clear trajectory towards extinction. These results outline the difficulties and uncertainties in relating probable population extinctions with climatic and land use changes in the case of invertebrate data. However, they also suggest that a third of the considered Spanish threatened species could have lost some of their populations, and that current conservation efforts are insufficient to reverse this tendency.

Effectiveness of three sampling methods to survey saproxylic beetle assemblages in Mediterranean woodland

The choice of sampling methods to survey saproxylic beetles is a key aspect to assessing conservation strategies for one of the most endangered assemblages in Europe. We evaluated the efficiency of three sampling methods: baited tube traps (TT), window traps in front of a hollow opening (WT), and emergence traps covering tree hollows (ET) to study richness and diversity of saproxylic beetle assemblages at species and family levels in Mediterranean woodlands. We also examined trap efficiency to report ecological diversity, and changes in the relative richness and abundance of species forming trophic guilds: xylophagous, saprophagous/saproxylophagous, xylomycetophagous, predators and commensals. WT and ET were similarly effective in reporting species richness and diversity at species and family levels, and provided an accurate profile of both the flying active and hollow-linked saproxylic beetle assemblages. WT and ET were the most complementary methods, together reporting more than 90 % of richness and diversity at both species and family levels. Diversity, richness and abundance of guilds were better characterized by ET, which indicates higher efficiency in outlining the ecological community of saproxylics that inhabit tree hollows. TT were the least effective method at both taxonomic levels, sampling a biased portion of the beetle assemblage attracted to trapping principles, however they could be used as a specific method for families such as Bostrichiidae, Biphyllidae, Melyridae, Mycetophagidae or Curculionidae Scolytinae species. Finally, ET and WT combination allows a better characterization of saproxylic assemblages in Mediterranean woodland, by recording species with different biology and linked to different microhabitat types.

Influence of tree hollow characteristics on the diversity of saproxylic insect guilds in Iberian Mediterranean woodlands

Saproxylic diversity assessment is a major goal for conservation strategies in woodlands and it should consider woodland composition and configuration at site and tree level as key modelling factors. However, in Mediterranean woodlands little is known about the relation with the environmental factors that structure their assemblages, especially those linked to tree hollow microhabitats. We assessed the diversity of Syrphidae (Diptera) and Coleoptera saproxylic guilds that co-occurred in tree hollows located in three different Iberian Mediterranean woodlands in the Cabañeros National Park (Spain). Furthermore, we evaluated how differences in tree hollow microenvironmental variables (understood as the physical and biotic characteristics of a hollow and tree individual) influenced saproxylic guild diversity both within and among woodland sites. We found that woodland sites that provided greater heterogeneity of trees and hollow microhabitats determined higher saproxylic guild diversity. Nevertheless, certain species or even complete guilds can be favoured in woodlands where some hollow microhabitats predominate as a consequence of historical tree management. In general, hollow volume was the main determining factor for saproxylic guild richness and abundance in woodland sites, and large hollow volume was usually related to higher diversity, which highlighted the importance of multi-habitat hollow trees. Moreover, saproxylic guilds also responded to other different microenvironmental variables, which indicated different ecological preferences among guilds. The conservation of saproxylic insects in Iberian Mediterranean areas must be addressed to protect woodland sites that provide high diversity and large numbers of tree hollow microhabitats, and practices to enhance microhabitat heterogeneity should even be encouraged.

Temporal variation in saproxylic beetle assemblages in a Mediterranean ecosystem

One of the main challenges in biological conservation has been to understand species distribution across space and time. Over the last decades, many diversity and conservation surveys have been conducted that have revealed that habitat heterogeneity acts as a major factor that determines saproxylic assemblages. However, temporal dynamics have been poorly studied, especially in Mediterranean forests. We analyzed saproxylic beetle distribution at inter and intra-annual scales in a “dehesa” ecosystem, which is a traditional Iberian agrosilvopastoral ecosystem that is characterized by the presence of old and scattered trees that dominate the landscape. Significant differences in effective numbers of families/species and species richness were found at the inter-annual scale, but this was not the case for composition. Temperature and relative humidity did not explain these changes which were mainly due to the presence of rare species. At the intra-annual scale, significant differences in the effective numbers of families/species, species richness and composition between seasons were found, and diversity partitioning revealed that season contributed significantly to gamma-diversity. Saproxylic beetle assemblages exhibited a marked seasonality in richness but not in abundance, with two peaks of activity, the highest between May and June, and the second between September and October. This pattern is mainly driven by the seasonality of the climate in the Mediterranean region, which influences ecosystem dynamics and imposes a marked seasonality on insect assemblages. An extended sampling period over different seasons allowed an overview of saproxylic dynamics, and revealed which families/species were restricted to particular seasons. Recognizing that seasons act as a driver in modelling saproxylic beetle assemblages might be a valuable tool in monitoring and for conservation strategies in Mediterranean forests.

What can physical, biotic and chemical features of a tree hollow tell us about their associated diversity?

Tree hollows are keystone structures for saproxylic fauna and host numerous endangered species. However, not all tree hollows are equal. Many variables including physical, biotic and chemical ones, can characterise a tree hollow, however, the information that these could provide about the saproxylic diversity they harbour has been poorly explored. We studied the beetle assemblages of 111 Quercus species tree hollows in four protected areas of the Iberian Peninsula. Three physical variables related to tree hollow structure, and two biotic ones (presence of Cetoniidae and Cerambyx species recognised as ecosystem engineers) were measured in each hollow to explore their relative effect on beetle assemblages. Moreover, we analysed the chemical composition of the wood mould in 34 of the hollows, in order to relate beetle diversity with hollow quality. All the environmental variables analysed (physical and biological) showed a significant influence on saproxylic beetle assemblages that varied depending on the species. Furthermore, the presence of ecosystem engineers affected both physical and chemical features. Although wood mould volume, and both biotic variables could act as beetle diversity surrogate, we enhance the presence of Cetoniidae and Cerambyx activity (both easily observable in the field) as indicator variables, even more if both co-occur as each affect to different assemblages. Finally, assimilable carbon and phosphorous contents could act as indicator for past and present beetle activity inside the cavity that could become a useful tool in functional diversity studies. However, an extension of this work to other taxonomic groups would be desirable.

Retrieval of phenological stages of onion fields during the first year of growth by means of C-band polarimetric SAR measurements

The phenological stages of onion fields in the first year of growth are estimated using polarimetric observables and single-polarization intensity channels. Experiments are undertaken on a time series of RADARSAT-2 C-band full-polarimetric synthetic aperture radar (SAR) images collected in 2009 over the Barrax region, Spain, where ground truth information about onion growth stages is provided by the European Space Agency (ESA)-funded agricultural bio/geophysical retrieval from frequent repeat pass SAR and optical imaging (AgriSAR) field campaign conducted in that area. The experimental results demonstrate that polarimetric entropy or copolar coherence when used jointly with the cross-polarized intensity allows unambiguously distinguishing three phenological intervals.