نتایج جستجو برای: oaks

تعداد نتایج: 1703  

2011
Heidi Paltto Anna Nordberg Björn Nordén Tord Snäll

Wooded pastures with ancient trees were formerly abundant throughout Europe, but during the last century, grazing has largely been abandoned often resulting in dense forests. Ancient trees constitute habitat for many declining and threatened species, but the effects of secondary woodland on the biodiversity associated with these trees are largely unknown. We tested for difference in species ric...

Journal: :The New phytologist 2018
Andrew L Hipp Paul S Manos Antonio González-Rodríguez Marlene Hahn Matthew Kaproth John D McVay Susana Valencia Avalos Jeannine Cavender-Bares

Oaks (Quercus, Fagaceae) are the dominant tree genus of North America in species number and biomass, and Mexico is a global center of oak diversity. Understanding the origins of oak diversity is key to understanding biodiversity of northern temperate forests. A phylogenetic study of biogeography, niche evolution and diversification patterns in Quercus was performed using 300 samples, 146 specie...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2013
Bret D Elderd Brian J Rehill Kyle J Haynes Greg Dwyer

Cyclic outbreaks of defoliating insects devastate forests, but their causes are poorly understood. Outbreak cycles are often assumed to be driven by density-dependent mortality due to natural enemies, because pathogens and predators cause high mortality and because natural-enemy models reproduce fluctuations in defoliation data. The role of induced defenses is in contrast often dismissed, becau...

Journal: :Tree physiology 2014
Tatiana A Shestakova Mònica Aguilera Juan Pedro Ferrio Emilia Gutiérrez Jordi Voltas

Identifying how physiological responses are structured across environmental gradients is critical to understanding in what manner ecological factors determine tree performance. Here, we investigated the spatiotemporal patterns of signal strength of carbon isotope discrimination (Δ(13)C) and oxygen isotope composition (δ(18)O) for three deciduous oaks (Quercus faginea (Lam.), Q. humilis Mill. an...

Journal: :Remote Sensing 2015
Marta Szulkin Przemyslaw Zelazowski Pascal Marrot Anne Charmantier

Environmental heterogeneity in space and time plays a key role in influencing trait variability in animals, and can be particularly relevant to animal phenology. Until recently, the use of remotely sensed imagery in understanding animal variation was limited to analyses at the population level, largely because of a lack of high-resolution data that would allow inference at the individual level....

Journal: :Scientific American 1907

Journal: :The British journal of general practice : the journal of the Royal College of General Practitioners 2010
Jeff Clark

We decided to work on this idea that GP registrars are competent but not confident. How can we help registrars to leave us not as saplings but as young oaks? In Bristol we now have speciality doctors for 18 months in general practice and if recommendation 45 of Sir John Tookes’ Report on Modernising Medical Careers is carried out then we will come into line with Europe. The length of training i...

Journal: :The American naturalist 2009
Walter D Koenig Johannes M H Knops William J Carmen Richard D Sage

We examined the relationship between acorn mass and number in valley oaks (Quercus lobata) over 4 years in central coastal California. Despite considerable variation in acorn size among both trees and years, trees produced acorns of the same size relative to other trees in different years. Across years, the relationship between acorn mass and acorn crop size was generally positive, even after c...

Journal: :Proceedings of the National Academy of Sciences 1916

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