نتایج جستجو برای: trees canopy

تعداد نتایج: 102028  

2003
M. R. Kurpius J. A. Panek N. T. Nikolov M. McKay A. H. Goldstein

The weather patterns of the west side of the Sierra Nevada Mountains (cold, wet winters and hot, dry summers) strongly influence how water is partitioned between transpiration and evaporation and result in a specific strategy of water use by ponderosa pine trees (Pinus ponderosa) in this region. To investigate how year-round water fluxes were partitioned in a young ponderosa pine ecosystem in t...

2006
Jeff Stringer

tain two distinct age classes in a forest. This system is generally initiated using a deferment harvest, sometimes referred to as a shelterwood or clearcut with reserves (Figure 1). The deferment harvest retains a limited basal area of canopy trees while allowing the majority of the area to regenerate. The harvest initially creates a stand that contains scattered or small groups of older trees,...

2003
Carolyn A. Copenheaver Marc D. Abrams

Eight jack pine (Pinus banksiana) stands in northern lower Michigan were sampled to evaluate the potential of dendroecological methods for studying stand dynamics with young trees. At each stand, a minimum of 20 dominant and codominant trees were cored, and at two stands additional recruitment data were collected. The cores were all cross-dated and measured. The raw ring widths were used to ide...

Journal: :جنگل و فرآورده های چوب 0
فاطمه رنجبر دانشجوی کارشناسی ارشد دانشکده منابع طبیعی دانشگاه گیلان کامبیز طاهری آبکنار دانشیار دانشکده منابع طبیعی دانشگاه گیلان کیومرث سفیدی استادیار دانشکده فناوری کشاورزی و منابع طبیعی دانشگاه محقق اردبیلی علی امیدی کارشناس ارشد اداره کل منابع طبیعی و آبخیزداری استان گیلان

the establishment and survival of seedlings is one of the main objectives of forest management which ensures continues production. the aim of this article is the investigation of dead trees effect on beech and hornbeam seedlings in masal's forests. for this reason, 30 dead trees were selected, and the control trees were selected in four aspects around the dead trees. they were the same as ...

Journal: :Tree physiology 1996
A. Arneth F. M. Kelliher G. Bauer D. Y. Hollinger J. N. Byers J. E. Hunt T. M. McSeveny W. Ziegler N. N. Vygodskaya I. Milukova A. Sogachov A. Varlagin E.-D. Schulze

Xylem sap flow and environmental variables were measured on seven consecutive midsummer days in a 130-year-old Larix gmelinii (Rupr.) Rupr. forest located 160 km south of Yakutsk in eastern Siberia, Russia (61 degrees N, 128 degrees E, 300 m asl). The site received 20 mm of rainfall during the 4 days before measurements, and soil samples indicated that the trees were well watered. The tree cano...

2003
Stephen Miller Ralph Scorza

Peach production in the U.S. relies on standard size trees on vigorous, seedling rootstocks grown at low-densities (≤ 297 trees/ha). Production per hectare is low. Peach tree growth habits, such as pillar (P) (columnar canopy shape) and upright (U), can be planted in high-density systems with the potential for increased production per hectare. Pillar and upright, advanced breeding selections, a...

2007
Neil Pederson Morgan Varner Brian J. Palik

Disturbance history was reconstructed across an 11300 ha managed longleaf pine (Pinus palustris Mill.) landscape in southwestern Georgia, USA. Our specific objectives were to: (i) determine forest age structure; (ii) reconstruct disturbance history through the relationship between canopy disturbance, tree recruitment and growth; and (iii) explore the relationship between canopy disturbance and ...

Journal: :Tree physiology 2009
Johan Uddling Ronald M Teclaw Kurt S Pregitzer David S Ellsworth

Increasing concentrations of atmospheric carbon dioxide (CO2) and tropospheric ozone (O3) have the potential to affect tree physiology and structure, and hence forest feedbacks on climate. Here, we investigated how elevated concentrations of CO2 (+45%) and O3 (+35%), alone and in combination, affected conductance for mass transfer at the leaf and canopy levels in pure aspen (Populus tremuloides...

Journal: :Remote Sensing 2009
Dimitrios Biliouris Dimitry Van der Zande Willem W. Verstraeten Bart Muys Pol Coppin

Multilayer canopy representations are the most common structural stand representations due to their simplicity. Implementation of recent advances in technology has allowed scientists to simulate geometrically explicit forest canopies. The effect of simplified representations of tree architecture (i.e., multilayer representations) of four Fagus sylvatica (L.) stands, each with different LAI, on ...

2017
Peter Elstner

On December 23-25, 1998, a major ice storm struck southeastern Virginia The storm-deposited glaze ice felled trees and limbs, causing a power outage and highway blockage. Between Februmy and April, 1999, we recorded occurrence, severity, and type of damage to trees over 2.5 cm dbh in nine mostly gently sloping plots in Matoaka Woods at the College of William and Macy. Frequency and severity of ...

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