Pine wilt disease and the pinewood nematode

Pine wilt disease (PWD) is one of the most damaging events affecting conifer forests (in particular Pinus spp.), in the Far East (Japan, China and Korea), North America (USA and Canada) and, more recently, in the European Union (Portugal). In Japan it became catastrophic, damaging native pine species (Pinus thunbergii and P. densiflora), and becoming the main forest problem, forcing some areas to be totally replaced by other tree species. The pine wilt nematode (PWN) Bursaphelenchus xylophilus, endemic, with minor damage, to North America, was introduced in Japan in the early XX century and then spread to Asia (China and Korea) in the 1980s. In 1999 it was detected for the first time in Portugal, where, due to timely detection and immediate government action, it was initially (1999-2008) contained to a small area 30 km SE of Lisbon. In 2008, the PWN spread again to central Portugal, the entire country now being classified as “affected area”. Being an A1 quarantine pest, the EU acted to avoid further PWN spreading and to eradicate it, by actions including financial support for surveyes and eradication, annual inspections and research programs. Experience from control actions in Japan included aerial spraying of insecticides to control the insect vector (the Cerambycid beetle Monochamus alternatus), injection of nematicides to the trunk of infected trees, slashing and burning of large areas out of control, beetle traps, biological control and tree breeding programs. These actions allowed some positive results, but also unsuccessful cases due to the PWN spread and virulence. Other Asian countries also followed similar strategies, but the nematode is still spreading in many regions. In Portugal, despite lower damage than Asia, PWD is still significant with high losses to the forestry industry. New ways of containing PWD include preventing movement of contaminated wood, cutting symptomatic trees and monitoring. Despite a national and EU legislative body, no successful strategy to control and eventually eradicate the nematode and the disease will prevail without sound scientific studies regarding the nematode and vector(s) bioecology and genetics, the ecology and ecophysiology of the pine tree species, P. pinaster and P. pinea , as well as the genomics and proteomics of pathogenicity (resistance/ susceptibility).

Vegetation series as a basis for habitats and species conservation: methodological aspects

Vegetation series, defined as the sequence of stages in a sucession, and know as sigmetum (synassociation), describes the set of plant communities or stages that can be found in similar tesselar spaces as a result of the sucession process. This establishes the concept of vegetation series; a climatophilous series is one that depends on the climate, whereas an edaphoxerophilous series depends on the dryness of the soil, and is found on crests, spurs, ledges and limestone and siliceous rock fields. Edaphohygrophilous series are located in valleys, dry water courses and river terraces, and depend on the water present in the soil, which may become temporarily flooded and thus condition the temporihygrophilous series; they represent the transition between the clearly edaphohygrophilous and climatophilous series. The vegetation permaseries represents the perennial communities of permatesselae or similar permatesselar complexes, as occurs in polar territories, hyperdesert, high-mountain peaks, and non-stratified communities lacking in serial communities. The edaphoxerophilous series may include -in addition to the series head- permaseries (permanent communities) and other habitats, such as annual and crevice habitats. A territory behaves undergoes soil-loss phenomena it may become an edaphoseries, if the loss of the soil factor produces a situation of rocky crest. Thus the edaphoseries may act as dynamic transitional stage between the climatophilous series and the permaseries.