Polywater: polymer or artifact?

Several polywater samples were prepared by the standard methods and have the same physical and spectroscopic properties as those made in other laboratories. However, a variety of chemical analyses show high concentrations of impurities which may account for many of the anomalous properties.     

Predicting soil loss in central and south Italy with a single USLE-MM model

Purpose

The USLE-MM estimates event normalized plot soil loss, A_e,N, by an erosivity term given by the runoff coefficient, Q_R, times the single-storm erosion index, EI₃₀, raised to an exponent b₁?>?1. This modeling scheme is based on an expected power relationship, with an exponent greater than one, between event sediment concentration, C_e, and the EI₃₀/P_e (P_e = rainfall depth) term. In this investigation, carried out at the three experimental sites of Bagnara, Masse, and Sparacia, in Italy; the soundness of the USLE-MM scheme was tested.

Materials and methods

A total of 1192 (A_e,N, Q_REI₃₀) data pairs were used to parameterize the model both locally and considering all sites simultaneously. The performances of the fitted models were established by considering all erosive events and also by distinguishing between events of different severity.

Results and discussion

The b₁ exponent varied widely among the three sites (1.05–1.44) but using a common exponent (1.18) for these sites was possible. The A_e,N prediction accuracy increased in the passage from the smallest erosion events (A_e,N?≤?1 Mg ha^?1, median error =?3.35) to the largest ones (A_e,N?>?10 Mg ha^?1, median error =?1.72). The Q_REI₃₀ term was found to be usable to predict both A_e,N and the expected maximum uncertainty of this prediction. Soil erodibility was found to be mainly controlled by the largest erosion events.

Conclusions

Development of a single USLE-MM model appears possible. Sampling other sites is advisable to develop a single USLE-MM model for a general use.

     

Relationships between rainfall characteristics and ephemeral gully erosion in a cultivated catchment in Sicily (Italy)

Recent research has shown a lack of long-term monitoring for detailed analysis of gully erosion response to climate characteristics. Measures carried out from 1995 to 2007 in a wheat-cultivated area in Raddusa (Sicily, Italy), represent one of the longest series of field data on ephemeral gully, EG, erosion. The data set collected in a surface area of almost 80 ha, permits analysis of the influence of rainfall on EG formation and development. Ephemeral gullies formed in the study area were measured on a yearly scale with a Post-Processing Differential GPS for length and with a steel tape for the width and depth of transversal sections. Ephemeral gully formation was observed for 8 years out of 12, which corresponds to a return period of 1.5 years. The measurements show strong temporal variability in EG erosion, in agreement with the rainfall characteristics. The total eroded volumes ranged between 0 and ca. 800 m³ year⁻¹, with a mean of ca. 420 m³ year⁻¹, corresponding to ca. 0.6 kg m⁻² year⁻¹. Ephemeral gully erosion in the study area is directly and mainly controlled by rainfall events. An antecedent rainfall index, the maximum value of 3-days rainfall (H_max3_d), is the rain parameter which best accounts for EG erosion. This index is used here as a simple surrogate for soil water content. An H_max3_d threshold of 51 mm was observed for EG formation. The return period of the H_max3_d threshold is almost the same as the return period for EG formation. Although a mean of seven erosive rain events were recorded in a year, EG formation and development generally occur during a single erosive event, similarly to other semiarid environments. The most critical period is that comprised between October and January, when the soil is wetter and the vegetation cover is scarce. Empirical models for EG eroded volume estimation were obtained using the data set collected at this site. A simple power-type equation is proposed to estimate the eroded volumes using H_max3_d as an independent variable. This equation shows an R² equal to 0.67 and a standard error of estimation of 0.79.     

Does afforestation increase bird nest predation risk in surrounding farmland?

Afforestation of agricultural land is increasingly used to deliver environmental benefits, but their effects on biodiversity remain poorly understood. This paper tests the hypothesis that afforestation changes predation processes in surrounding farmland, examining how the characteristics and landscape context of forest plantations affect predator (birds and mammalian carnivores) and key prey (rabbits and hares) abundances, and bird nest predation rates in Iberian cereal-steppes. Lagomorphs and predators were surveyed in fallow fields around 50 forest plantations, where predation rates were estimated using artificial nests set at 0, 100, 200 and 300 m from the forest edge. Recent plantations structurally similar to sparse (oak) or dense (pine) shrublands were associated with the highest hare and rabbit abundances, respectively, whereas both species avoided landscapes with high eucalyptus cover. In contrast, mature eucalyptus plantations showed strong positive effects on typical nest predators such as corvids and carnivores. Open farmland fragmentation favoured the abundance of lagomorphs and carnivores. Despite these effects and the high predation rate on artificial nests (49%), there was neither evidence for increased predation near plantation edges nor higher predation in fields with more lagomorphs and predators. However, predation tended to increase with cover by young oak plantations and overall forest plantation cover, to decrease with eucalyptus cover at both the local and landscape scales, and to peak in landscapes with intermediate edge densities. These results suggest that afforestation may have strong effects on bird nest predation rates by changing landscape composition and configuration, rather than by inducing local increases in predator and prey populations. Nevertheless, increased abundances of generalist predators associated with forest plantations may still be considered of conservation concern, thus supporting the recommendation for strongly restricting afforestation in areas important for open grassland birds. Where this is unavoidable, monitoring should be undertaken to provide early signals for bird population declines associated with predator increases, eventually triggering conservation action such as predator exclusion or removal.     

Forest fuel management as a conservation tool for early successional species under agricultural abandonment: The case of Mediterranean butterflies

In cultural landscapes there are often negative biodiversity consequences of agricultural abandonment and subsequent scrub and forest encroachment, due to homogenization and the loss of early-successional habitats. The common forestry practice of removing understory vegetation to prevent fire hazard (fuel management) probably has the side-effect of ameliorating these consequences, but it is uncertain whether it effectively restores habitats for early-successional species. Here we examine the influence of time since fuel management and management frequency on butterfly assemblages, using a chronosequence of cork oak (Quercus suber) stands spanning about 70 years. Overall species richness increased immediately after management and abundances peaked about 2–3 years later, while both declined thereafter for about 10–20 years to pre-disturbance levels. Richness and abundances were also much higher in recurrently managed stands. Most life history groups showed successional trends similar to the overall species richness and abundances, though consistent positive effects of fuel management were only observed for species with univoltine life cycle, herbaceous layer feeding, larval overwintering, and intermediate body size. Individual species were largely associated with recent and recurrent management, though a few specialists occurred most often in undisturbed stands. These findings suggest that fuel management at <10 years intervals is strongly positive for butterfly assemblages in landscapes under land abandonment. However, to maintain the overall forest biodiversity it is critical that patches of undisturbed habitat are also retained at the landscape scale.     

Nanoparticles in the management of brown eye spot in coffee

European Journal of Plant Pathology - Brown eye spot (Cercospora coffeicola) is one of the main diseases of coffee (Coffea arabica L.) and represents a serious phytosanitary problem for the crop....