Whereas most of the research on phloem loading is performed on herbaceous plants, less is known about phloem loading strategies in trees. In this study, the phloem loading mechanisms of Quercus robur and Fraxinus excelsior were analysed. The following features were examined: the minor vein structure, the sugar concentrations in phloem sap by the laser-aphid-stylet technique, the distribution of...

PREMISE OF THE STUDY Geography and climate shape the distribution of organisms, their genotypes, and their phenotypes. To understand historical and future evolutionary and ecological responses to climate, we compared the association of geography and climate of three oak species (Quercus engelmannii, Quercus berberidifolia, and Quercus cornelius-mulleri) in an environmentally heterogeneous regio...

The composition and temporal variation in species recruitment were examined in relation to annual dendrochronological data to determine the historical development and successional history of an old-growth mixed-oak (Quercus) forest in northern Virginia, USA. A ridge site in the upland Piedmont, along the Potomac River, was used to survey the old-growth forest, which is dominated by Quercus alba...

PREMISE OF THE STUDY Although long-distance pollen movement is common in wind-pollinated trees, barriers to gene flow may occur in species that have discontinuous ranges or are confined to certain habitat types. We investigated the genetic structure of Quercus lobata Née populations throughout much of their range in California. We assessed the connectivity of populations and determined if barri...

This study evaluates and quantifies the variation in vegetation, plant nutrients, and microclimate across four topographic aspects in an Appalachian watershed (398399430N, 798459280W). The study found that the north and east aspects were 27–50% more productive than the west and southwest aspects. Species groups that showed strong aspect preference included yellow poplar (Liriodendron tulipifera...

The taxonomy of oaks (Quercus) is always a challenge because many species exhibit variable phenotypes that overlap with other species. The scrub White Oaks of California are no exception. In California, Quercus section Quercus (i.e., White Oaks) includes six species of scrub oaks plus four tree oak species. Field identification utilizes leaf traits and acorns, when available, as well as geograp...

1 Corresponding author: [email protected]; (850) 644-8385; fax: (850) 644-5913 2 Current address: Graduate Program in the School of Forest Resources & Environmental Science, Michigan Tech, 1400 Townsend Drive, Houghton, MI 49931-1295 USA ABSTRACT: The ravines along the Apalachicola River are recognized for their species-rich mixed hardwood forests. Although steep slopes may have limited l...

Pollen morphology of three parental Quercus species (Q. robur L., Q. petraea (Matt) Liebl, Q. pubescens Willd.) and two spontaneous hybrids of these species (Q. ×calvescens Vuk. = Q. petraea × Q. pubescens and Q. ×rosacea Bechst. = Q. robur × Q. petraea) was investigated in this study. The pollen originated from 18 natural oak sites and 67 individuals (oak trees). Each individual was represente...

Question: What are the responses of epiphytic lichens to the intensity of management along a large environmental gradient in Mediterranean Quercus forests? Location: Central Spain. Methods: This study was carried out on 4590 trees located in 306 forest stands dominated by Quercus faginea or Quercus ilex ssp. ballota. The effect of forest management and other predictor variables on several speci...

We used 126 Sherman live traps on a 9 by 14 grid at the University of California Santa Cruz Forest Ecology Research Plot (FERP) to look at small mammal diversity in a mixed evergreen forest. The ability for Peromyscus boylii and Peromyscus californicus to coexist in the same area is believed to be a form of niche partitioning at the canopy level. We used multivariate logistic regression to look...