نتایج جستجو برای: birch tree

تعداد نتایج: 174023  

2003
Sylvain Jutras Hannu Hökkä Virpi Alenius Hannu Salminen

Multilevel logistic regression models were constructed to predict the 5-year mortality of Scots pine (Pinus sylvestris L.) and pubescent birch (Betula pubescens Ehrh.) growing in drained peatland stands in northern and central Finland. Data concerning tree mortality were obtained from two successive measurements of the National Forest Inventory-based permanent sample plot data base covering pur...

2004
Xiaowei Yu Juha Hyyppä Hannu Hyyppä Matti Maltamo

High-density airborne laser scanner data has been previously shown to provide great opportunities for individual tree detection and measurement of variables characterizing the detected trees. This paper evaluates the effect of laser flight altitude on the tree height estimation at individual tree level in the boreal forest area mainly consisting of Norway spruce, Scots pine and birch. The test ...

Journal: :Tree physiology 2006
Michael J Daley Nathan G Phillips

Transpiration is generally assumed to be insignificant at night when stomata close in response to the lack of photosynthetically active radiation. However, there is increasing evidence that the stomata of some species remain open at night, which would allow for nighttime transpiration if there were a sufficient environmental driving force. We examined nighttime water use in co-occurring species...

Journal: :Tree physiology 2004
Sylvain Delagrange Christian Messier Martin J Lechowicz Pierre Dizengremel

In a 4-year study, we investigated changes in leaf physiology, crown morphology and whole-tree biomass allocation in seedlings and saplings of shade-tolerant sugar maple (Acer saccharum Marsh.) and intermediate shade-tolerant yellow birch (Betula alleghaniensis Britt.) growing in natural understory light (0.5 to 35% of full sunlight) or in understory light reduced by 50% with shade nets to simu...

Journal: :Tree physiology 2007
Ivika Ostonen Krista Lõhmus Heljä-Sisko Helmisaari Jaak Truu Signe Meel

Variability in short root morphology of the three main tree species of Europe's boreal forest (Norway spruce (Picea abies L. Karst.), Scots pine (Pinus sylvestris L.) and silver birch (Betula pendula Roth)) was investigated in four stands along a latitudinal gradient from northern Finland to southern Estonia. Silver birch and Scots pine were present in three stands and Norway spruce was present...

2013
Ivika Ostonen Katrin Rosenvald Heljä-Sisko Helmisaari Douglas Godbold Kaarin Parts Veiko Uri Krista Lõhmus

Morphological plasticity of ectomycorrhizal (EcM) short roots (known also as first and second order roots with primary development) allows trees to adjust their water and nutrient uptake to local environmental conditions. The morphological traits (MTs) of short-living EcM roots, such as specific root length (SRL) and area, root tip frequency per mass unit (RTF), root tissue density, as well as ...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه علوم کشاورزی و منابع طبیعی گرگان - دانشکده جنگلداری و مهندسی چوب و کاغذ 1387

چکیده ندارد.

Journal: :Clinical and experimental allergy : journal of the British Society for Allergy and Clinical Immunology 2008
C Egger M Focke A J Bircher K Scherer N Mothes-Luksch F Horak R Valenta

BACKGROUND Beech and oak pollen are potential allergen sources with a world-wide distribution. OBJECTIVE We aimed to characterize the allergen profile of beech and oak pollen and to study cross-reactivities with birch and grass pollen allergens. METHODS Sera from tree pollen-allergic patients with evidence for beech and oak pollen sensitization from Basel, Switzerland, (n=23) and sera from ...

2009
I. Korpela T. Tokola H. O. Ørka M. Koskinen

In forest inventories, the species information is crucial for economical, ecological and technical reasons. Species recognition is currently a bottleneck in practical remote sensing applications. Here, we examined species discrimination using tree-level LiDAR features in discrete-return data. The aim was to examine the robustness and explanatory power of the intensity and height distribution fe...

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