Effects of rainfall and simulated browsing on the growth of Acacia georginae (F.M. Bailey) in arid central Australia.

1990 ◽  
Vol 12 (2) ◽  
pp. 79 ◽  
Author(s):  
DF Robinson ◽  
JR Maconochie ◽  
PJ Hanna
Keyword(s):  
Soil Moisture ◽  
Leaf Growth ◽  
Growth Patterns ◽  
Subsequent Growth ◽  
Leafy Shoots ◽  
Central Australia ◽  
Simulated Browsing

Leafy shoots of Acacia georginae were subjected to different combinations of pruning and defoliation, and their subsequent growth patterns recorded over two and a half years. Rainfall and soil moisture records were also kept. Rainfall, soil moisture, new growth and old leaf loss showed variable patterns from year to year and generally were not strongly related to each other. Light pruning was followed by increased leaf growth, with apparent stimulation, whereas heavy pruning and defoliation appeared to be detrimental to growth, mainly in that removed growth was not replaced. Actual inhibition could not be established.

scholarly journals Interactive effects of ambient ozone and climate measured on growth of mature loblolly pine trees

1996 ◽  
Vol 26 (4) ◽  
pp. 670-681 ◽  
Author(s):  
S.B. McLaughlin ◽  
D.J. Downing
Keyword(s):  
Soil Moisture ◽  
Loblolly Pine ◽  
Moisture Stress ◽  
Growth Patterns ◽  
Forest Growth ◽  
Interactive Effects ◽  
Forest Trees ◽  
Short Term ◽  
Data Set ◽  
Ambient Ozone

Seasonal growth patterns of mature loblolly pine (Pinustaeda L.) trees over the interval 1988–1993 have been analyzed to evaluate the effects of ambient ozone on growth of large forest trees. Patterns of stem expansion and contraction of 34 trees were examined using serial measurements with sensitive dendrometer band systems. Study sites, located in eastern Tennessee, varied significantly in soil moisture, soil fertility, and stand density. Levels of ozone, rainfall, and temperature varied widely over the 6-year study interval. Regression analysis identified statistically significant influences of ozone on stem growth patterns, with responses differing widely among trees and across years. Ozone interacted with both soil moisture stress and high temperatures, explaining 63% of the high frequency, climatic variance in stem expansion identified by stepwise regression of the 5-year data set. Observed responses to ozone were rapid, typically occurring within 1–3 days of exposure to ozone at ≥40 ppb and were significantly amplified by low soil moisture and high air temperatures. Both short-term responses, apparently tied to ozone-induced increases in whole-tree water stress, and longer term cumulative responses were identified. These data indicate that relatively low levels of ambient ozone can significantly reduce growth of mature forest trees and that interactions between ambient ozone and climate are likely to be important modifiers of future forest growth and function. Additional studies of mechanisms of short-term response and interspecies comparisons are clearly needed.

scholarly journals Temperature and moisture dependence of daily growth of Scots pine (Pinus sylvestris L.) roots in Southern Finland

2019 ◽  
Vol 40 (2) ◽  
pp. 272-283
Author(s):  
Yiyang Ding ◽  
Pauliina Schiestl-Aalto ◽  
Heljä-Sisko Helmisaari ◽  
Naoki Makita ◽  
Kira Ryhti ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Pinus Sylvestris ◽  
Scots Pine ◽  
Growth Patterns ◽  
Root Production ◽  
Summer Drought ◽  
Daily Growth ◽  
Drought Effect ◽  
Fibrous Roots ◽  
Root Types

Abstract Scots pine (Pinus sylvestris L.) is one of the most important conifers in Northern Europe. In boreal forests, over one-third of net primary production is allocated to roots. Pioneer roots expand the horizontal and vertical root systems and transport nutrients and water from belowground to aboveground. Fibrous roots, often colonized by mycorrhiza, emerge from the pioneer roots and absorb water and nutrients from the soil. In this study, we installed three flatbed scanners to detect the daily growth of both pioneer and fibrous roots of Scots pine during the growing season of 2018, a year with an unexpected summer drought in Southern Finland. The growth rate of both types of roots had a positive relationship with temperature. However, the relations between root elongation rate and soil moisture differed significantly between scanners and between root types indicating spatial heterogeneity in soil moisture. The pioneer roots were more tolerant to severe environmental conditions than the fibrous roots. The pioneer roots initiated elongation earlier and ceased it later than the fibrous roots. Elongation ended when the temperature dropped below the threshold temperature of 4 °C for pioneer roots and 6 °C for fibrous roots. During the summer drought, the fibrous roots halted root surface area growth at the beginning of the drought, but there was no drought effect on the pioneer roots over the same period. To compare the timing of root production and the aboveground organs’ production, we used the CASSIA model, which estimates the aboveground tree carbon dynamics. In this study, root growth started and ceased later than growth of aboveground organs. Pioneer roots accounted for 87% of total root productivity. We suggest that future carbon allocation models should separate the roots by root types (pioneer and fibrous), as their growth patterns are different and they have different reactions to changes in the soil environment.

scholarly journals Aerodynamic Resistance and Penman–Monteith Evapotranspiration over a Seasonally Two-Layered Canopy in Semiarid Central Australia

2013 ◽  
Vol 14 (5) ◽  
pp. 1562-1570 ◽  
Author(s):  
James Cleverly ◽  
Chao Chen ◽  
Nicolas Boulain ◽  
Randol Villalobos-Vega ◽  
Ralph Faux ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Drag Coefficient ◽  
Vapor Pressure Deficit ◽  
Soil Moisture Content ◽  
Aerodynamic Resistance ◽  
Atmospheric Humidity ◽  
Vapor Transfer ◽  
Central Australia ◽  
Content Information

Abstract Accurate prediction of evapotranspiration E depends upon representative characterization of meteorological conditions in the boundary layer. Drag and bulk transfer coefficient schemes for estimating aerodynamic resistance to vapor transfer were compared over a semiarid natural woodland ecosystem in central Australia. Aerodynamic resistance was overestimated from the drag coefficient, resulting in limited E at intermediate values of vapor pressure deficit. Large vertical humidity gradients were present during the summer, causing divergence between momentum and vapor transport within and above the canopy surface. Because of intermittency in growth of the summer-active, rain-dependent understory and physiological responses of the canopy, leaf resistance varied from less than 50 s m−1 to greater than 106 s m−1, in which the particularly large values were obtained from inversion of drag coefficient resistance. Soil moisture limitations further contributed to divergence between actual and reference E. Unsurprisingly, inclusion of site-specific meteorological (e.g., vertical humidity gradients) and hydrological (e.g., soil moisture content) information improved the accuracy of predicting E when applying Penman–Monteith analysis. These results apply regardless of canopy layering (i.e., even when the understory was not present) wherever atmospheric humidity gradients develop and are thus not restricted to two-layer canopies in semiarid regions.

Effect of grazed lucerne on the moisture status of wheat-growing soils

1978 ◽  
Vol 18 (90) ◽  
pp. 112 ◽  
Author(s):  
ICR Holford ◽  
AD Doyle
Keyword(s):  
Soil Moisture ◽  
Grain Yield ◽  
Soil Water ◽  
New South ◽  
Cropping System ◽  
Wheat Crop ◽  
Subsequent Growth ◽  
South Wales ◽  
Severe Reduction ◽  
Available Soil Moisture

The effects of varying durations of lucerne ley and subsequent wheat cropping on the moisture status of contrasting wheat growing soils are reported from two experiments in northern New South Wales. Lucerne leys of 5 1/2, 3 1/2 and 1 1/2 years on a red brown earth and 3 1/2, 2 1/2, and 1 1/2 years on a black earth were compared with a wheat-cowpea rotation, long fallow and continuous wheat. Lucerne extracted available soil water within eight months of sowing to a depth of 100 cm, with partial extraction of water to 150 cm. Within 18 months available water to a depth of 200 cm had been extracted. Subsequent growth of lucerne was dependent on incident rainfall and water extraction from depths greater than 200 cm. Wheat extracted water from the soil only to a depth of 150 cm, and extracted less water to this depth than did lucerne. Lucerne extracted water beyond the -1 5 bar suction level. On the black earth, soil moisture at 150 cm had not been recharged before time for sowing the third wheat crop, 28 months after lucerne plough-out. On the red brown earth, after a drought enforced long fallow immediately following lucerne plough-out, soil water at 200 cm was recharged within 18 months. Available soil moisture after three to five months fallow following plough-out of the lucerne leys was much less than for a wheat cropping system, with a consequent severe reduction in the grain yield of the following wheat crop. On the black earth grain yield was reduced by 7.7 kg ha-1 for each reduction of 1 mm in available moisture in the first crop after lucerne plough-out. Data indicate that lucerne must be ploughed out before January if a severe reduction in yield of the following wheat crop is to be minimized.

scholarly journals Gestational Diabetes and Subsequent Growth Patterns of Offspring: The National Collaborative Perinatal Project

2011 ◽  
Vol 16 (1) ◽  
pp. 125-132 ◽  
Author(s):  
Kesha Baptiste-Roberts ◽  
Wanda K. Nicholson ◽  
Nae-Yuh Wang ◽  
Frederick L. Brancati
Keyword(s):  
Gestational Diabetes ◽  
Growth Patterns ◽  
Subsequent Growth
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