8 research outputs found

    Status of Charcoal Canker on Oak Trees at a Site of Community Importance: Case Study of the Relict Castelfidardo Forest (SIC Area IT520008, Castelfidardo, AN, Italy)

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    Oaks are dominant and key tree species in Mediterranean forest ecosystems. However, in recent decades, oak forests have been heavily impacted by oak decline, a worldwide phenomenon exacerbated by climate change. The charcoal disease agent Biscogniauxia mediterranea is involved in the decline of Mediterranean oak formations in a variety of contexts. Here, we investigated the impact and role of B. mediterranea in the decline of oaks in Castelfidardo Forest, a relict wood of the late Holocene and a Site of Community Importance. We established five plots within which we recorded tree positions, any symptoms and signs of decline, association of B. mediterranea to declining trees, and deadwood and associated mycota. Of 471 oaks inspected, 7.0% showed brownish exudates on the stems, 46.9% showed epicormic shoots along the main trunk, and 24.4% showed black carbonaceous stromata on diseased branches and trunks. The decline was most severe for Quercus cerris, which comprised plots #4 and #5, at 50.0% (81/162 trees) and 29.0% (33/114), respectively; then for Quercus robur for plot #3, at 40.0% (38/95); and finally for Quercus pubescens for plots #1 and #2, at 13.7% (7/51) and 12.3% (6/49), respectively. Bark tissues were collected from trees with charcoal cankers and taken to the laboratory for microscopic examination and identification by mycological and molecular methods. This investigation revealed a close association between oaks with pronounced reduction of vitality and incidence of B. mediterranea. Deadwood was equally distributed among the five plots, and was heavily colonized by Basidiomycota. The high incidence of the charcoal canker pathogen B. mediterranea appeared to be related to environmental stresses. However, the absence of silvicultural management, high competition among physiologically mature trees, and the geographic isolation of this residual forest may have predisposed oaks to decline

    A tale of two hearth sites:Neolithic and intermittent mid to late Holocene occupations in the Jubbah oasis, northern Saudi Arabia

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    Hearth sites are characteristic of Holocene occupation in the Arabian sand seas but remain mostly unstudied. Excavations of two multi-period hearth sites in the Jebel Oraf palaeolake basin, in the oasis of Jubbah, now substantially increase our knowledge of these sites. In total, 17 of 170 identified hearths were excavated at Jebel Oraf 2 (ORF2), an open-air site on the edge of a palaeolake. In addition, 11 hearths were excavated at the stratified site of Jebel Oraf 115 (ORF115), a rockshelter formed by two boulders. Radiocarbon dating and lithic assemblages indicate that the majority of these hearths were in use in the second half of the 6th millennium BCE, and that both sites were used sporadically until the recent past. All hearths appear to have been extremely short-lived, and faunal remains suggest they may have been used to cook meat from hunted or trapped wildlife, and occasionally from livestock. The frequent use of grinding stones, often broken into fragments and used to cover hearths is also attested. Evidence for the exceptionally early use of metal from dated occupation deposits as well as from rock art, shows that these short-lived sites were well connected to technological innovations in the wider region
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