scholarly journals Covering Tree Line with Black Poly Ethylene Sheets for Composting Fresh Animal Manures Reduces Weeds and Improves Tree Growth in Newly Established Orchards

2011 ◽  
Vol 02 (05) ◽  
pp. 675-682 ◽  
Author(s):  
Barakat Abu Irmaileh ◽  
Azmi Abu Rayyan ◽  
Fahmi Shatat
Keyword(s):  
Tree Growth ◽  
Tree Line ◽  
Animal Manures ◽  
Covering Tree ◽  
Poly Ethylene

Drought limitation on tree growth at the Northern Hemisphere’s highest tree line

2019 ◽  
Vol 53 ◽  
pp. 40-47 ◽  
Author(s):  
Lixin Lyu ◽  
Qi-Bin Zhang ◽  
Marlow G. Pellatt ◽  
Ulf Büntgen ◽  
Mai-He Li ◽  
...  
Keyword(s):  
Tree Growth ◽  
Tree Line

scholarly journals Use of modeled photosynthesis and decomposition to describe tree growth at the northern tree line

2004 ◽  
Vol 24 (2) ◽  
pp. 193-204 ◽  
Author(s):  
F. Berninger ◽  
P. Hari ◽  
E. Nikinmaa ◽  
M. Lindholm ◽  
J. Merilainen
Keyword(s):  
Tree Growth ◽  
Tree Line

scholarly journals Tree Growth Variability of Pinus heldreichii at Tree-Line Locations in Kosovo

2020 ◽  
Vol 11 (2) ◽  
pp. 135-144
Author(s):  
Faruk Bojaxhi ◽  
Ervin Toromani ◽  
Nehat Çollaku
Keyword(s):  
Tree Ring ◽  
Tree Growth ◽  
Low Temperatures ◽  
Ring Width ◽  
Tree Line ◽  
Seasonal Growth ◽  
Mountain Slope ◽  
Scientific Software ◽  
Growth Variability ◽  
Breast Height

It is well-known that tree growth at the upper treeline is controlled by low temperatures and limited seasonal growth. The study’s objective was to investigate the climate warming effects on Bosnian pine (BP; Pinus heldreichii Christ.) growth during the 20th century. We hypothesized that, like all the other drought-stressed conifers growing on tree-line locations, BP responds significantly to climate factors that control their growth. Three natural forest stands of BP were selected in Prevalla, Decan and Koritnik. The cores were taken from 98 dominant and co-dominant BP trees at breast height with no sign of human interference. The tree-ring widths were measured at 0.001 mm precision, with a LINTAB 6 (RINNTECH, Heidelberg) system and TSAP-Win Scientific software. A set of three BP tree-ring width chronologies were developed by trees spread on a typical mountain slope at elevations ranging from 1815 to 1945 m above sea level. The tree-ring chronologies from three sites showed significant correlation and this agreement decreased with the distance between sites. The length of the master chronologies varies among sites ranging from 176 years (Koritnik) to 541 years (Decani). The tree growth was controlled by a common climatic signal (local temperatures) and drought during midsummer across the investigated sites. These results confirm the assumption that tree growth at tree-line sites is controlled by low temperatures and drought conditions during the midsummer.

scholarly journals Tree-line changes along the Andes: implications of spatial patterns and dynamics

2006 ◽  
Vol 362 (1478) ◽  
pp. 263-272 ◽  
Author(s):  
Kenneth R Young ◽  
Blanca León
Keyword(s):  
Spatial Patterns ◽  
Tree Growth ◽  
Spatial Organization ◽  
Morphological Plasticity ◽  
Landscape Patterns ◽  
Research Approach ◽  
Tree Line ◽  
Climate Fluctuations ◽  
The Andes ◽  
Species Specific

The Andes provide an extensive latitudinal and topographical framework for studying the factors that control the spatial patterns of forests (timberlines) and their species components expressed through the presence of tree growth forms (tree lines). Despite consistent overall similarities in landscape patterns, many processes must be unique, given the dramatic differences in species richness and biophysical constraints along the Andes. In all cases evaluated to date, morphological plasticity is a common trait of plant species that dominate at tree lines. In fact, many changes observed can be related to species-specific traits. Physiological limitations on tree growth form only explain species limits, while disturbances and cyclical climate fluctuations interact to affect many landscape patterns. Over long periods of time, tree lines provide unique habitats and perhaps opportunities for speciation. Understanding the spatial organization of tree-line dynamics is one viable research approach for evaluating the likely past fluxes and possible future changes.

Climate change and tree-ring relationships of Nothofagus menziesii tree-line forests

2001 ◽  
Vol 31 (11) ◽  
pp. 1981-1991 ◽  
Author(s):  
Louise E Cullen ◽  
Jonathan G Palmer ◽  
Richard P Duncan ◽  
Glenn H Stewart
Keyword(s):  
New Zealand ◽  
Tree Ring ◽  
Climate Warming ◽  
Tree Growth ◽  
Natural Disturbance ◽  
Tree Line ◽  
Climatic Control ◽  
Influence Of Temperature On ◽  
Summer Temperatures ◽  
The Impact

To assess the sensitivity of New Zealand tree lines to climate warming, we compared the tree-ring growth characteristics and temperature relationships of silver beech (Nothofagus menziesii (Hook. f.) Oerst) at two elevations, ca. 1200 m (tree line) and ca. 1100 m. Modelled relationships between climate series and tree rings indicated that the main climatic control on tree growth was current summer temperatures. Nevertheless, temperatures during earlier seasons can influence tree growth, pointing to a complex relationship between radial growth and climate at tree line. Overall, the similarity in the growth–temperature relationships for trees at both elevations indicated that high-altitude N. menziesii forests should be useful for examining the impact of climate warming on tree growth. However, the level of common growth variation was greater in the below tree line chronologies, suggesting that other factors, including natural disturbance, may affect or compete with the influence of temperature on tree-ring growth at tree line. Despite the importance of summer temperatures for tree growth at or near tree line and the reported increase in summer temperatures since 1950 in New Zealand, ring widths have not increased in recent decades. We conclude, therefore, that in these N. menziesii tree-line forests there has been no detectable tree-ring growth response to climate warming.

The Structure of Radiation Cross-Linked Poly (ethylene oxide) Gels

1971 ◽  
Vol 29 ◽  
pp. 76-77
Author(s):  
C. E. Cluthe ◽  
G. G. Cocks
Keyword(s):  
Molecular Weight ◽  
Ethylene Oxide ◽  
Parallel Plate ◽  
Average Molecular Weight ◽  
Radical Reaction ◽  
Free Radical Reaction ◽  
Nitrogen Gas ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene ◽  
Initial Viscosity

Aqueous solutions of a 1 weight-per cent poly (ethylene oxide) (PEO) were degassed under vacuum, transferred to a parallel plate viscometer under a nitrogen gas blanket, and exposed to Co60 gamma radiation. The Co60 source was rated at 4000 curies, and the dose ratewas 3.8x105 rads/hr. The poly (ethylene oxide) employed in the irradiations had an initial viscosity average molecular weight of 2.1 x 106.The solutions were gelled by a free radical reaction with dosages ranging from 5x104 rads to 4.8x106 rads.

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