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Bark Area (bark + area)

Distribution by Scientific Domains

Earth and Environmental Science	100%

Selected Abstracts

Soil type and microtopography influencing feeding above and below ground by the pine weevil Hylobius abietis

AGRICULTURAL AND FOREST ENTOMOLOGY, Issue 2 2005
Göran Nordlander
Abstract 1,The influence of soil type and microtopography on above and below ground feeding by adult pine weevils Hylobius abietis (L.) (Coleoptera: Curculionidae) was evaluated in a field experiment with enclosed weevil populations of known size. 2,Four soil treatments, each with a food source at the centre, were presented within each enclosure: (i) a flat surface with fine-grained, cultivated humus; (ii) a flat surface with sand; (iii) a conical mound of sand; and (iv) a conical pit in sand. The food source consisted of a stem section of Scots pine Pinus sylvestris L. extending both above and below ground. 3,The majority of feeding on the half buried stem sections occurred below ground; only 2.7% of the total bark area consumed was situated above ground. The variation over time in bark area consumed was not significantly associated with any of the tested weather factors. 4,The amount of feeding was 10-fold higher on food sources placed in fine-grained humus than those in areas of flat sand. 5,Less pine bark was consumed on mounds of sand than flat sand surfaces, and there was more feeding in sandy pits than on flat sand. These effects on feeding are explained by the observation that the weevils had difficulties climbing the sandy slopes (27° gradient). 6,We conclude that pine weevil damage to conifer seedlings can be considerably reduced by planting on mounds of pure mineral soil and that planting deeply in the soil increases the risk of damage. [source]

Feeding by the pine weevil Hylobius abietis in relation to sun exposure and distance to forest edges

AGRICULTURAL AND FOREST ENTOMOLOGY, Issue 3 2003
Göran Nordlander
Abstract, 1,The intensity of feeding by adult pine weevils Hylobius abietis (L.) on the stem bark of Norway spruce Picea abies (L.) Karst. seedlings planted in rows with a north,south orientation across a clear-cutting, was measured throughout a growth season. The feeding was then correlated to light interception, soil temperature and distance to the nearest forest edge. 2,Feeding was at least twice as intense on seedlings in the central part of the clear-cutting compared to those at the edges. The decline began approximatety 15 m from the edge and was of similar proportions on both the sun-exposed and shaded sides. 3,Measures of global radiation and soil temperature correlated well with consumption on the shaded side. However, on the sun-exposed side, there were no apparent correlations with global radiation or soil temperature that could explain the decline in consumed bark area. 4,We conclude that the decline in feeding towards the forest edges was mainly due to factors other than the microclimate variables we monitored. We suggest that the presence of roots of living trees along the forest edge may reduce damage to seedlings, since they provide an alternative source of food for the weevils. This alternative-food hypothesis may also explain why seedlings in shelterwoods usually suffer less damage from pine weevils than seedlings in clear-cuttings. [source]

Tree age is a key factor for the conservation of epiphytic lichens and bryophytes in beech forests

APPLIED VEGETATION SCIENCE, Issue 1 2009
Örjan Fritz
Abstract Questions: What factors limit the distribution of epiphytic lichens and bryophytes at plot and tree level in beech forests? At what ages do epiphytic species, and species of conservation concern in particular, occur along a chronosequence of beech? Location: South-west Sweden. Method: Five hundred and seventy-one age-determined trees from 37 plots distributed among 29 beech-dominated stands were surveyed along with a number of environmental (16) and substrate (seven) variables in a landscape of ca. 550 ha. Non-metric multidimensional scaling (NMS) and indicator species analysis (ISA) were used for data analysis. Results: Plots containing old trees, confined to the base of slopes and with low impacts of recent forestry (thinning), generally had a high richness of species of conservation concern. Richness of common species and red-listed bryophytes were mostly related to the surveyed bark area. At tree level, primary factors explaining both species richness and composition were age, diameter at breast height and moss cover. There was a gradual replacement of tree age ranges for 58 lichens and 37 bryophytes along the chronosequence of beech. Red-listed lichens favoured damaged beech trees (,180 years), whereas red-listed bryophytes were found on old and young stems in dense stands. Conclusions: Tree age exerts a profound influence on epiphytic lichens and bryophytes growing on beech. Many of the habitat specialists were found mainly on old beech because they inhabit specific substrates that occur on older trees. The association to high tree age commonly excludes red-listed lichens from conventionally managed beech forests with a 100- to 140-year rotation period. [source]