Short- and intermediate-term effects of site and plant preparation techniques on reforestation of a Mediterranean semiarid ecosystem with <Emphasis Type="Italic">Pinus halepensis</Emphasis> Mill

A 5-year study of the reforestation of a semiarid Mediterranean ecosystem with Pinus halepensis is presented. Reforestation of Mediterranean semiarid ecosystems is challenging as a result of harsh environmental conditions and historical human exploitation leading to degradation. New techniques have to be developed in order to increase survivorship and growth that integrates nursery and field treatments. A total of 60 treatments resulting from 12 site × 5 plant preparation techniques were tested. Plant preparation consists of mycorrhizing in nursery, extra fertilizing in nursery, planting in containers in the nursery, planting in the field with a polypropylene tube, and control plants (bred in plastic bags). Soil preparation consists of hole, subsoiling without amendment, subsoiling with composted organic amendment added in the surface or in the furrow of plantation and subsoiling with fresh organic amendment added in the surface or in the furrow of plantation. Each one of these treatments was tested with a hydrophilic acrylic copolymer and without it. Survivorship was very high (0.91) given the prevailing environmental conditions. Subsoiling promoted higher survival than holes, and plants bred in containers had lower levels of survivorship than control ones. Protecting seedlings with polypropylene tubes had no effect on survivorship. The most effective treatment for promoting growth was organic amendment, the effect of which increased until the fourth year. Protection with tubes was very effective in increasing height, although only in the short-term. Subsoiling also promoted faster growth than holes, although the effect was less noticeable after 3 years and was, in any case, less effective than organic amendment. Other treatments promoting faster growth were the use of fresh organic waste as opposed to composted waste and its incorporation in the plantation furrow rather than as a layer on the surface. The addition of hydrophilic acrylic copolymer reduced growth during the first months of the reforestation. The fertilization of plants in the nursery and inoculation with spores of mycorhyzal fungi did not improve seedling growth. Plants bred in containers performed worse than control plants bred in individual plastic bags. The findings suggests the importance of nutrient supply in semiarid environments, an aspect that has been previously neglected in favor of water supply. Organic amendments reinforce both and can be recommended as long as adequate environmental controls are in place.     

Influence of geographical location, site and silvicultural parameters, on volatile composition of Quercus pyrenaica Willd. wood used in wine aging

For the current study, the volatile and semi-volatile composition of several samples of Quercus pyrenaica wood from NW Spain were analyzed and compared. The research was performed on a wide sample set of more than 100 samples (test tubes) obtained from different stands of this species. The relationship between some silvicultural and site parameters and volatile composition was studied. Altitude seemed to be the most influential parameter on the volatile composition. However, other factors such as distance from tree center, average annual precipitation, and number of trees per hectare whose effects on the volatile compounds were not significant. The influence of soil texture was not a determining factor while geographical location seemed to have a more specific impact on the extractive volatile content. The content of all extractable compounds studied allowed a good separation of oak samples of the same species according to their geographical origin.     

Tannins and mimosine in Leucaena genotypes and their relations to Leucaena resistance against Leucaena Psyllid and Onion thrips

The study was conducted throughout two seasons (2013 and 2014) at Xmatkuil farm at Merida, Yucatan, Mexico, to determine the relationships and the interactions between chemical compositions of condensed tannins and mimosine and their effects on the susceptibility of four Leucaena genotypes: Cunningham and K636 (L. leucocephala), and Nativa and KX2 (L. leucocephala × L. pallida) to the infestation of the most destructive insect pests; Leucaena Psyllids, Heteropsylla cubana Crawford, 1914 (Homoptera: Psyllidae), and Onion thrips, Thrips tabaci Lindeman, 1889 (Thysanoptera: Thripidae). Mimosine showed insignificant effect on the population of both pests. However, tannins exhibited a significant effect for Psyllid population on Nativa and K636, and highly significant effect on thrips for the same respective genotypes. The insignificant relationships of tannin effect were found for Cunningham and KX2 to the population fluctuations of Psyllid and Thrips.     

Prediction of stand quality characteristics in sweet chestnut forests in NW Spain by combining terrain attributes, spectral textural features and landscape metrics

Chestnut woods are outstanding elements of European cultural landscapes, and are also recognised as habitats of interest in the Natura 2000 European network of protected areas. Despite their importance, they are threatened by land abandonment and recent rural landscape changes. The loss of Castanea sativa cover and its dominance as a characteristic species may indicate forest degradation, which can occur as a result of natural succession dynamics or invasion by alien species.In this study we aimed to model the conservation status of chestnut stands in the NW Iberian peninsula in terms of their environmental and cultural value, formulated as a quality index that considers the maturity and purity of forest stands. We used features available at wide geographic scales as potential predictors, namely topographic parameters derived from Digital Elevation Models, land-cover heterogeneity determined by means of satellite image texture and landscape metrics. According to the results, altitude emerged as a major factor determining chestnut stand quality, marking a clear difference between highland and lowland environments. The combination of terrain, texture and patch shape refined the classification of each of these scenarios. We discuss the significance of these predictors as environmental controls and indicators of anthropogenic effects.     

Time to rethink the management intensity in a Mediterranean oak woodland: the response of insectivorous birds and leaf-chewing defoliators as key groups in the forest ecosystem

? Context

The Iberian cork oak Quercus suber montados are dynamic agro-silvo-pastoral systems, contrasting with the abandonment trend of other Mediterranean forested areas.

? Aims

We aimed to identify the effect of management type and vegetation features on breeding insectivorous birds and leaf-chewing defoliator insects.

? Methods

In central Portugal, we selected two groups of 20 sites: dense montados (DM, high cover of cork oaks and low cattle impact) and sparse montados (SM, low cover of oaks and high cattle impact). We collected variables associated with vegetation features, bird community and chewing defoliators.

? Results

The two systems differed significantly in oak trunk diameter, oak and shrub cover, tree and shrub diversity. Ground bird densities were higher in SM with fragmented shrub cover. In DM, higher woody vegetation cover and diversity can promote shrub birds and leaf warblers. Oak defoliation was mainly attributed to the sawfly Periclista andrei. Sawfly defoliation was significantly higher in SM and negatively correlated with shrub cover.

? Conclusions

Our results highlight (1) the relevance of management activities conducted at the shrubby layer, (2) the need of an increase in tree diversity and density and (3) the maintenance of a mosaic landscape in order to improve the bird community richness and reduce the defoliation impact in montado system.     

Bacteria-phage antagonistic coevolution in soil

Bacteria and their viruses (phages) undergo rapid coevolution in test tubes, but the relevance to natural environments is unclear. By using a "mark-recapture" approach, we showed rapid coevolution of bacteria and phages in a soil community. Unlike coevolution in vitro, which is characterized by increases in infectivity and resistance through time (arms race dynamics), coevolution in soil resulted in hosts more resistant to their contemporary than past and future parasites (fluctuating selection dynamics). Fluctuating selection dynamics, which can potentially continue indefinitely, can be explained by fitness costs constraining the evolution of high levels of resistance in soil. These results suggest that rapid coevolution between bacteria and phage is likely to play a key role in structuring natural microbial communities.     

TLR3 deficiency in patients with herpes simplex encephalitis

Some Toll and Toll-like receptors (TLRs) provide immunity to experimental infections in animal models, but their contribution to host defense in natural ecosystems is unknown. We report a dominant-negative TLR3 allele in otherwise healthy children with herpes simplex virus 1 (HSV-1) encephalitis. TLR3 is expressed in the central nervous system (CNS), where it is required to control HSV-1, which spreads from the epithelium to the CNS via cranial nerves. TLR3 is also expressed in epithelial and dendritic cells, which apparently use TLR3-independent pathways to prevent further dissemination of HSV-1 and to provide resistance to other pathogens in TLR3-deficient patients. Human TLR3 appears to be redundant in host defense to most microbes but is vital for natural immunity to HSV-1 in the CNS, which suggests that neurotropic viruses have contributed to the evolutionary maintenance of TLR3.     

A NEWLY RECOGNIZED PATTERN OF CANINE OSTEOCHONDROMATOSIS

Clinicopathological findings are described for a unique skeletal pattern of osteochondromatosis (syn. multiple osteochondromas) in three crossbred littermate dogs. Multiple nonpainful bilaterally symmetric skeletal lesions arose from focal semiannular and annular areas of periosteal thickening on the cortical surface of the metaphyses and diaphyses of long bones. Flat bones of the skull were spared. In radiographs osteochondromas in different stages of evolution were apparent. Grossly there were smoothly contoured, nodular subperiosteal masses of dense fibrocartilaginous and osseous tissue that were continuous with and overlying apparently normal but thin trabeculae of cancellous bone. Cortical compacta was attenuated or absent beneath exostoses. In histologic sections of the cartilage-capped exostoses a hyperplastic periosteum formed a focal semiannular or annular cap of proliferative hyaline cartilage tissue that underwent endochondral ossification and replacement by cancellous bone at its base. Intertrabecular spaces in the cancellous bone of exostoses were filled with fibro-osseous and hematopoietic tissue. A hereditary origin was suspected for the osteochondromas. Origin of some osteochondromas as semiannular or annular perturbations of the perichondrial ring of metaphyseal physes of long bones likely contributed to limb shortening and a pattern of billaterally symmetric angular limb deformities of all limbs as occurs in some children affected by osteochondromatosis.     

Biological activity of some Patagonian plants

Citotoxicity (inhibition of cell division in fertilized eggs of Loxechinus albus) and general toxicity (using embryos of Artemia salina) of plants belonging to the genera Senecio, Deschampsia, Alstroemeria, Anarthrophyllum, Chloraea and Geranium were investigated.