Acorn Isotopic Composition: A New Promising Tool for Authenticity Maps of Montado's High-Value Food Products

It is often overlooked that even food production is linked to the ecology of plants and animals. Living organisms respond to environmental short-and long-term variability: acknowledging this may help in the ultimate goal of valorizing a territory/product. We investigated acorns of the two main Quercus species of the Portuguese Montado, a main feed of the renown black Iberian pig. We tested their responses to an aridity gradient by morphological parameters and isotopic signature. Q. rotundifolia and Q. suber acorns did not differ morphologically, even if a higher variability in all parameters was observed in acorns of Q. suber. According to the site-specific Aridity Index, correlations are indicative to higher weight and length only in Q. suber acorns from more arid sites. As for isotopic composition, there were no differences in nitrogen or carbon (δ15N and δ13C) between the two species. However, combining the samples and testing for association with the Aridity Index, we found that more arid sites lead to a 15N enrichment. This result, combined with the positive correlation between AI and acorns length, support the use of acorns as a tool, their isoscapes of nitrogen being a stepping stone for the provenance of the black Iberian pig.

Abundance and Population Decline Factors of Chrysopid Juveniles in Olive Groves and Adjacent Trees

Numerous species of the family Chrysopidae, commonly found in agroecosystems, whose larvae predate on several pests of economic importance, are regarded as biological control agents. Their abundance and diversity are influenced by vegetation cover, although little is known about the effects of semi-natural habitats on their populations. The objective of this study is to gain a better understanding of the relationship between the trees in semi-natural habitats adjacent to olive groves, juvenile stages of the family Chrysopidae and factors influencing their population decline, which is crucial for an effective habitat management program aimed at conserving these important predators. Using cardboard band traps (eight per tree), the juvenile stages were collected from 25 almond, oak, olive and pine trees over a one-year sampling period. The population decline was caused by parasitoids (26.5%), predators (5.1%) and unknown factors (13.2%). In addition, chrysopids established in olive trees showed the lowest rate of parasitism. We identified ten chrysopid species that emerged from the juveniles collected from almond, oak, olive and pine trees, with a predominance of Pseudomallada prasinus. The chrysopid–parasitoid complex was composed of five species; Baryscapus impeditus (Eulophidae), which was the most abundant, was preferentially associated with Chrysopa pallens, Chrysoperla lucasina and Chrysoperla mediterranea.

Bacteria and Hoverflies (Diptera: Syrphidae) in Tree Hollows From the Iberian Mediterranean Forest

Saproxylic insect communities inhabiting tree hollows in Mediterranean forests depend on a combination of physical characteristics and interactions occurring between community member species. Despite the need to preserve these organisms, little is known about their interrelationships, in particular those relationships between saproxylic insects and microbiota occurring in these microhabitats. In tree hollows of Quercus rotundifolia Lamark that hold water and contain dead leaves, abundant microbial populations can be found. Developing on them are the larvae of Mallota dusmeti Andréu, 1926 (Diptera: Syrphidae), a vulnerable species (IUCN category: Marcos-García and Quinto 2011). This study provides the first data on the microbiota living inside the gut of the larvae of M. dusmeti, as well as the microbiota in the hollow where these larvae develop. Bacteria were identified by amplification and partial sequencing of the V1-V3 regions and the complete nucleotide sequence of 16S rRNA genes. We found eight species of bacteria living in tree hollows and three species in the gut of M. dusmeti larvae: Bacillus cereus, Bacillus toyonensis, and Lysinibacillus sphaericus. The filter-feeding mechanism characteristic of M. dusmeti larvae is selective in enabling ingestion of bacteria only above 2.1 µm in diameter.

Fragmentation patterns of evergreen oak woodlands in Southwestern Iberia: identifying key spatial indicators

Mediterranean evergreen oak woodlands (composed of Quercus suber L. and Quercus rotundifolia Lam.) are becoming increasingly fragmented in the human-modified landscapes of Southwestern Portugal and Spain. Previous studies have largely neglected to assess the spatial changes of oak woodlands in relation to their surrounding landscape matrix, and to characterize and quantify woodland boundaries and edges. The present study aims to fill this gap by analyzing fragmentation patterns of oak woodlands over a 50-year period (1958-2007) in three landscapes. Using archived aerial imagery from 1958, 1995 and 2007, for two consecutive periods (1958-1995 and 1995-2007), we calculated a set of landscape metrics to compare woodland fragmentation over time. Our results indicated a continuous woodland fragmentation characterized by their edge dynamics. From 1958 to 2007, the replacement of open farmland by shrubland and by new afforestation areas in the oak woodland landscape surrounding matrix, led to the highest values for edge contrast length trends of 5.0 and 12.3, respectively. Linear discriminant analysis was performed to delineate fragmented woodland structures and identify metric variables that characterize woodland spatial configuration. The edge contrast length with open farmland showed a strong correlation with F1 (correlations ranging between 0.55 and 0.98) and may be used as a proxy for oak woodland mixedness in landscape matrix. The edge dynamics of oak woodlands may result in different patterns of oak recruitment and therefore, its study may be helpful in highlighting future baselines for the sustainable management of oak woodlands.