Assessing the impact of understory vegetation cut on soil epigeic macrofauna from a cork-oak Montado in South Portugal

Cork oak “Montados” are a particular Mediterranean ecosystem, which can be found in Southern Portugal. Portuguese “Montados” are man-made ecosystems, mainly used for cork production and cattle farming, that support a high biological diversity. Current sustainable management techniques imply a shrub clearing with heavy machinery, which can be highly disruptive for soil biota. In order to evaluate the effects of understory vegetation management on soil epigeic macrofauna, five zones were defined along a chronosequence of shrub clearing: a non-disturbed zone (zone 5) and zones where understory vegetation was cut at 4–5 years (zone 4), at 3–4 years (zone 3), at 2 years (zone 2) and at 1 year (zone 1). A sixth zone (zone 6) was selected in a pasture, where cattle are occasionally present. Soil fauna was sampled using “pitfall” traps and sampling took place in autumn 2003. A total of 2,677 individuals, separated into 152 species and morphospecies, were caught in the traps. With the exception of zone 6, that presented a lower number of species, all the other zones from the chronosequence presented, in most cases, a similar number of taxa, species diversity (Shannon) and species richness (Margalef). Multivariate analysis separated recently disturbed zones (plus zone 6) from those intervened at longer time; groups like Formicidae, Scydmaenidae, most families from Araneae and insect larvae appeared closely associated to zones 3–5 (with a higher shrub cover and thick litter layers), whereas, other Hymenoptera, Gastropda and most Coleoptera families, appeared associated to recently disturbed zones (zones 1 and 2) and to zone 6, characterized by a lower shrub cover and a lower accumulation of litter. This separation indicates that effects of the intervention can endure for 2 or 3 years. After that time, the normal natural regeneration of the understory vegetation seems to support the restoration of the macrofauna community, thus indicating that the sustainable management strategy adopted, i.e., making a shrub cut every 5–6 years, seems not induce a significant effect on local species richness of soil epigeic macrofauna.     

Conservation of Mediterranean oak woodlands: understorey dynamics under different shrub management

The effect of experimental disturbances on the dynamics of a shrub community was studied on a ‘Montado’ ecosystem, in southern Portugal. The evolution of the community physiognomy, composition and diversity were monitored after shrub clearing followed by biomass removal, deposition on soil surface and incorporation with the soil, over a 9-year period. Maximum shrub density was recorded in the first year after the disturbances, excepting in mulched plots which showed the greatest number of individuals 1 year later. The increment of shrub leaf biomass was very fast in the first 3 years, whereas wood production was slower but occurred along the whole study period. At the end of the study, leaf and wood biomass was still significantly lower than in the pre-disturbance situation. The variation pattern of leaf area index was similar to that of leaf biomass. The evolution of total plant cover and diversity was similar across treatments. The highest species richness and diversity were recorded 2 years after cutting, decreasing afterwards with the increasing dominance of shrubs. Thus it seems likely that, although a 9 year period is too short for these communities to reach steady equilibrium, they are very resistant and resilient to disturbances, as regeneration was fast and vegetation dynamics was not influenced by differences among treatments. We can conclude that shrub clearing promotes biodiversity and the time of permanence of shrub patches depends on the particular goal we want to achieve.     

Regulation of lysine metabolism and endosperm protein synthesis by the opaque-5 and opaque-7 maize mutations

Two high lysine maize endosperm mutations, opaque-5 (o5) and opaque-7 (o7), were biochemically characterized for endosperm protein synthesis and lysine metabolism in immature seeds. Albumins, globulins, and glutelins, which have a high content of lysine, were shown to be increased in the mutants, whereas zeins, which contain trace concentrations of lysine, were reduced in relation to the wild-type lines B77xB79+ and B37+. These alterations in the storage protein fraction distribution possibly explain the increased concentration of lysine in the two mutants. Using two-dimensional polyacrylamide gel electrophoresis of proteins of mature grains, variable amounts of zein polypeptides were detected and considerable differences were noted between the four lines studied. The analysis of the enzymes involved in lysine metabolism indicated that both mutants have reduced lysine catabolism when compared to their respective wild types, thus allowing more lysine to be available for storage protein synthesis.     

A global stochastic index for water quality: The case of the river Turia in Spain

Which are applicable in all Member States. Those directives specify a set of physical and chemical characteristics, which depend on the use the water is intended for, the parameters to be regularly controlled in a network of sampling points, and the limiting values of those parameters for each quality level. Hence, an administrative quality classification for each sampling point is obtained. This article proposes a stochastic quality index that takes into account the uncertainty surrounding the quality classification still remaining after the data have been observed. This stochastic index is built with the probability classification vector of each parameter. In order to obtain those vectors, a mixed-lognormal model is introduced and its statistical analysis developed. The methodology proposed here is then applied to the data observed in the La Presa station, one of the sampling points of the Spanish surface water quality network. Located on the river Turia, near the city of Valencia, its aim is to control the quality of water intended for the abstraction of drinking water. Its stochastic quality classification is obtained and compared with the legally applicable administrative one.     

Analysis of phenolic compounds in the evaluation of commercial quince jam authenticity

The phenolic compounds present in 17 samples of Portuguese commercial and three homemade quince jams were analyzed by reversed-phase HPLC/DAD, to determine their authenticity. Two different extraction methods were needed for the complete definition of quince jams profiles, one of them including an Amberlite XAD-2 cleaning step. These analyses showed that all the samples presented a similar profile composed of at least eight identified phenolic compounds, several unidentified characteristic procyanidin polymers, and sodium benzoate as preservative of quince jams. Several samples also contained arbutin, suggesting that these quince jam samples were fraudulently adulterated with pear puree.     

The primary gene pool of cassava (Manihot esculenta Crantz subspecies esculenta, Euphorbiaceae)

The primary gene pool (GP-1) of a crop is composed of gene reservoirs that cross easily with the domesticated, while the crosses regularly produce fertile offspring. The GP-1 is further subdivided into cultivated and wild gene pools. The cultivated gene pool encompasses commercial stocks of the crop, as well as landraces. The wild GP-1 of the crop comprises putative ancestors and closely related species that show a fair degree of fertile relationships with the domesticate. Two South American wild subspecies of cassava (M. flabellifolia and M. peruviana) were proposed as natural members of the wild GP-1 of the crop. Another Brazilian species(M. pruinosa) is morphologically so close to both wild subspecies that it may turn out as another member of the wild GP-1. This revised version was published online in July 2006 with corrections to the Cover Date.     

Assessment of genetic relationships among Pyrus species and cultivars using AFLP and RAPD markers

Twenty-five Pyrus communis L. cultivars including eight traditional Portuguese pears, and four commercial Pyrus pyrifolia (Burm.) Nak. (Japanese pear or `nashi') cultivars were analysed by RAPD and AFLP techniques focusing on their molecular discrimination and the assessment of their genetic relatedness. Twenty-five primers generated 324 RAPD markers, among which 271 (84%) were polymorphic. The AFLP technique, using seven primer combinations, revealed a similar level of molecular polymorphisms (87%), representing 418 polymorphic bands among a total of 478 scored in autoradiographs. The high reproducibility of RAPD and AFLP techniques was confirmed comparing DNA samples from different extractions and different digestions of DNA from the same plant. Three genetic similarity matrices and respective dendrograms were elaborated on using RAPD, AFLP or joint RAPD and AFLP data. Both molecular marker techniques proved their reliability to assess genetic relationships among pear cultivars. P. pyrifolia cultivars exhibit a closer genetic relatedness, clustering apart from P. communis cultivars. Within P. communis, `William's', as well as `Doyenne du Comice', cluster close to their hybrids. Most of the Portuguese cultivars tend to cluster together, indicating to constitute a relatively independent genetic pool, which can be of interest in pear breeding programs.     

Alkaline hydrolyzable nitrogen and properties that dictate its distribution in paddy soil profiles

Nitrogen (N) is a key nutrient for rice production, and its bioavailability in paddy soils is strongly coupled to soil organic matter (SOM) cycling. A better understanding of potentially available N forms in soil, such as alkaline hydrolyzable N (AH-N), and their depth distribution will support the development of best management practices to improve the N use efficiency of rice while minimizing adverse environmental effects. Fifteen rice (Oryza sativa L.) fields from Southern Brazil were selected, and stratified soil samples were taken to a depth of 60 cm before crop establishment. Selected soil physical and chemical properties were analyzed to evaluate their relationships with AH-N contents in the soil profile. The AH-N contents below 20 cm varied extensively (increased, reduced, or constant) compared with that above 20 cm. Although clay and clay + silt contents were highly correlated to AH-N for some soils, the major property dictating AH-N distribution by depth was total N (TN), as the correlation between TN and AH-N was mainly by direct effect. The proportion of TN recovered as AH-N across sites and depths presented high amplitude, and thus AH-N was not a constant N pool across depths, indicating that AH-N can be affected by soil management practices even when TN showed no major changes. The distinct distribution of AH-N across soil sampling sites and depths indicates that depths greater than 20 cm should be considered when calibrating the AH-N index for N fertilizer recommendations for flooded rice in Southern Brazil.     

Effects of Plant Age on Arsenic Hyperaccumulation by Pteris vittata L.

Plant age affects its elemental uptake and biomass accumulation, which is important for the application of plants in phytoextraction. In this research, we evaluated the effects of plant age on arsenic accumulation by arsenic hyperaccumulator Pteris vittata after growing in an arsenic-contaminated soil for 8 weeks. The study used a completely randomized design consisting of four plant ages (2, 4, 10 and 16 months) with four replications each. While the fronds of the 2 month old plants contained 36% more arsenic than those of the 4 and 16 month old plants, they were lower in roots. After 8 weeks of growth, the final frond biomass increased by 39, 6.9, 2.0 and 1.1 times compared to the initial frond biomass, from youngest to oldest, respectively. Higher phosphorus and iron accumulation in the roots of older plants may have affected the plant’s efficiency to bioconcentrate and transfer arsenic from the roots to the fronds. Greater metabolic activity and higher rate of biomass production lead to higher As accumulation and removal by young plants. This research demonstrated that the use of young plants can be an effective strategy to reduce the time to remediate an As-contaminated site.     

Impact of anthropogenic activity on the Hg concentrations in the Piracicaba river basin (São Paulo State, Brazil)

A sampling and analysis program has been completed between 1995 and 1998 in order to determine mercury concentrations in water, sediments, soils and fish in the Piracicaba river basin, one of the most populated and industrialized regions in Brazil. In sediment, the average Hg concentrations varied between 33 ± 17 ng g^?1 and 106 ± 78 ng g^?1, in samples collected during the rainy and dry season, respectively. The same averages were also found for soil samples (35 ± 14 and 109 ± 61 ng g^?1). In water, the total Hg concentration varied between < 1.1 and 24.0 ng L^?1. In piscivore fish, up to 943 μ g Hg kg^?1 was found. Our results show that all compartments undergo Hg contamination, in view of the levels found in pristine environments. Water contamination seems to be due mainly to diffuse processes of soil erosion and suspension of river bed sediment during the rainy season. Also untreated wastewaters generated by industrial activities and from domestic sewage appear to be potential non-point sources in the most industrialized and populated part of the basin. On the other hand, atmospheric transport of mercury originating from the Campinas Metropolitan Region could be another source of mercury contamination, especially in the basin headwaters.