نتایج جستجو برای: trees canopy

تعداد نتایج: 102028  

Journal: :Tree physiology 2002
Robert M Hubbard Barbara J Bond Randy S Senock Michael G Ryan

Recent studies have shown that stomata respond to changes in hydraulic conductance of the flow path from soil to leaf. In open-grown tall trees, branches of different heights may have different hydraulic conductances because of differences in path length and growth. We determined if leaf gas exchange, branch sap flux, leaf specific hydraulic conductance, foliar carbon isotope composition (delta...

2009
A. S. Antonarakis K. S. Richards J. Brasington M. Bithell

[1] Strategies for extracting roughness parameters from riparian forests need to address the issue that the trees are more than just stems and that in large rivers flow can rise into the canopy. Remote sensing information with 3-D capabilities such as lidar can be used to extract information on trees. However, first and last pulse airborne lidar data are insufficient to characterize the complex...

This study was carried out to investigate the effect of crown canopy of Pistacia atlantica, Amygdalus scoparia and A. eburnea species on seed bank density (size). Ten individuals of each species were selected and one plot under and another plot outside of the crown canopy of each species were established. In each plot, soil sampling was done from 0-5 and 5-10 cm depths. The soil seeds were id...

The Nearest Individual Sampling Method is one of the distance sampling methods for estimating density, canopy cover and height of forest stands. Some distance sampling methods have more than one density estimator that may be skewed to the spatial pattern. Unless the stands of the trees under study have a random spatial pattern. Therefore, the purpose of this study was evaluating the effect of s...

2002
Janet Franklin Frank W. Davis Paul Lefebvre

T h e effect of variable tree canopy cover, shadows, and topography on Thematic Mapper (TM) data was examined for blue oak (Quercus douglasii) woodland and wooded grassland on rugged terrain in central California. Thematic Mapper data were analyzed from September 1986 (trees in leaf, grass understory senescent) and December 1984 (trees leafless, grasses emerging. Tree cover measured in 84 60 m ...

2001
MATTHEW B. DICKINSON SHARON M. HERMANN

Isolated canopy gaps involving one to several trees occur continuously and frequently in many moist and wet neotropical forests (sensu Holdridge et al. 1971), shaping tree community structure through a shifting mosaic of patches of high resource availability for small and young trees (Denslow 1980). Though there are few relevant data (Jans et al. 1993), forests with significant seasonal drought...

2015
Beatriz Ibáñez Lorena Gómez-Aparicio Peter Stoll José M. Ávila Ignacio M. Pérez-Ramos Teodoro Marañón

In forests, the vulnerable seedling stage is largely influenced by the canopy, which modifies the surrounding environment. Consequently, any alteration in the characteristics of the canopy, such as those promoted by forest dieback, might impact regeneration dynamics. Our work analyzes the interaction between canopy neighbors and seedlings in Mediterranean forests affected by the decline of thei...

1999
Dale G. Brockway Kenneth W. Outcalt

Naturally regenerated seedlings of longleaf pine are typically observed to cluster in the center of tree fall canopy gaps and be encircled by a wide zone from which they are generally excluded. Twelve representative canopy gaps distributed across 600 ha of a naturally regenerated uneven-aged longleaf pine forest in the sandhills of north central Florida were examined to determine which abovegro...

بنی هاشمی, ضیاءالدین, حمزه زرقانی, حبیب ‌الله,

A field survey was carried out in Firoozabad Beneh (Pistacia mutica) Forest Station covering about 12000 hectares. Data were collected using combined random and systematic sampling methods to study the effect of altitude, dominant slope direction, sex and age of the host and plant canopy on rust severity caused by Pileolaria terebinthi. The rust severity decreased with plant age and elevations ...

2007
MUSTAFA SARI N. KEMAL SONMEZ MEHMET KARACA

Understanding the spectral features of Washington navel trees is important to remotely measure and monitor the canopy properties and biochemical changes in plantations. Satellite and ground based passive remote sensing techniques have been widely used in many plant species. However, the use of these techniques in orange trees is limited. In this study, relationships between total chlorophyll (C...

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