Drought responses of an exotic tree (Eriobotrya japonica) in a tropical cloud forest suggest the potential to become an invasive species

New Forests - Eriobotrya japonica is a non-native tree expanding in secondary forests and threatening the tropical montane cloud forest of central Veracruz, Mexico. Our objective was to investigate...     

Distribution and stand characteristics of relict populations of Mexican beech (Fagus grandifolia var. mexicana)

Fagus grandifolia var. mexicana (Mexican beech) is limited to about 10 populations (2-35 ha) in the Sierra Madre Oriental, Mexico. The objectives were to assess the current status and distribution of beech by surveying five sites. Species richness varied between three to 27 tree species in the canopy, and from nine to 29 species in the understorey. Basal area of trees?5 cm dbh varied between 27.87 and 70.98 m² ha⁻¹, and density from 370 to 1290 individual ha⁻¹. Beech represented 22-99.6% of total basal area, and 6.8-83.3% of total density. Beech dominance varied from monodominant to codominance with Carpinus caroliniana, Quercus spp., Liquidambar styraciflua, Magnolia schiedeana, and Podocarpus spp. Beech total population size ranged from 180 to 6300 trees with a total of less than 1300 individuals in four sites. Anthropogenic disturbance remains a major threat to these forests. It is uncertain whether Mexican beech will be able to survive without conservation efforts.     

Remediation of contaminated soil using soil washing and biopile methodologies at a field level

Background, Aims and Scope  An out-of-service oil distribution and storage station (ODSS), which operated from 1966 to 2000 in Mexico, is contaminated mainly by gasoline and diesel, showing the presence of methyl-tert-butyl-ether, benzene, toluene, ethyl benzene, and xylenes. Nine of the 16 polycyclic aromatic hydrocarbons were found, as well as Fe, Pb, V, and Zn. The health risk assessment suggested the necessity of reducing of three PAHs [benzo(a)anthracene, benzo(a)pyrene, and benzo-(b)fluoranthene], and vanadium. The aim of this work is to show that soil washing (on-site) and biopiles are excellent remediation methodologies to treat soils contaminated with petroleum derivates and metals. Applying them, it is possible to reach the goal value of 2,000 mg TPH/kg in a few months, as requested by Mexican legislation. Methods  More than 140 m³ were excavated from the ODSS. Three soil-washing dishes were built. 1540 m³ were treated by soil washing using a nonionic surfactant. A 100 m³ biopile was built to study the system capabilities in the biodegradation of around 4,500 mg/kg of TPH using the autochthonous microflora. Results and Discussion  The soil washing, average TPH-removal value was 83%, but values up to ca. 93% were observed. Removal values resulted in a function of the TPH initial values. Biopile (100 m³) worked during 66 days, reaching a TPH-removal value of 85%. At the end of the processes, no PAHs were detected. The contaminated soil was treated successfully, reaching the legislation limits (TPH values under 2,000 mg/kg, and a significant reduction in PAH concentrations). Conclusion and Recommendation  Both systems are suitable for remediation purposes, achieving high removal efficiencies at short and medium stages. It is highly recommended to proceed with soil washing studies, identifying new products, and mixtures, which could reduce costs and assure optimum operation.     

Characterization of <Emphasis Type="Italic">Fusarium</Emphasis> species associated with tobacco diseases in Northwestern Argentina

Phenotypic traits are regularly used to diagnose the development of Fusarium head blight (FHB) in the field, whereas mycotoxin accumulation in wheat grains can only be accurately evaluated through costly methods, such as high–performance liquid chromatography (HPLC). The aim of this study was to determine whether: (i) the results provided by existing commercial decision support tools could be anticipated using phenotypic measurements, including a novel technique of computer–assisted image analysis of spikes; and (ii) these measurements could avoid using HPLC. We monitored the FHB development during two consecutive years in highly contaminated plots in the Burgundy region (France). Contamination by crop residues was simulated through a field inoculation with barley grains artificially colonized by Fusarium graminearum. The development of the disease on spikes and harvested grains was assessed on one tolerant and two susceptible wheat varieties. The accumulated amounts of mycotoxins were measured in harvested grains using HPLC. As expected, the measured traits revealed that the inoculum responsible for infection on spikes mainly came from residues left on the soil surface, and the susceptible varieties were more diseased than the tolerant variety. Weather conditions had a strong effect on disease development. The novel computer–assisted image analysis technique had a better prediction power of deoxynivalenol accumulation, was more objective and time–saving than classical visual symptom assessments. This assessment method could be suitable to supplement the use of existing prediction tools and might avoid systematic and costly mycotoxin measurements in likely infected plots.