Canopy Dynamics of Eucalyptus Maculata Hook. I. Distribution and Dynamics of Leaf Populations

1984 ◽  
Vol 32 (4) ◽  
pp. 387 ◽  
Author(s):  
EW Pook
Keyword(s):  
Water Supply ◽  
Leaf Area ◽  
Shoot Growth ◽  
Temperature Limit ◽  
Leaf Fall ◽  
Leaf Production ◽  
Area Index ◽  
Average Size ◽  
Non Destructive

The canopy dynamics of a regenerated 16-year-old stand of pole and sapling E. maculata were studied for 2½ years by repetitive non-destructive measurements in tree crowns accessed from a 20 m high scaffold tower. Average canopy leaf area density over a sample plot of 36 m2 was 0.23 m2 m-3 at a leaf area index of 4.3. Some 75% of leaf area was held in the canopies of overstorey eucalypts above 10 m in height. Average size of leaves increased gradually from top to bottom of tree canopies. Foliage production was usually concentrated in the upper crowns of trees where there was a higher proportion of active shoots, more frequent growth flushes and more rapid turnover of leaves than in lower canopy layers. Leaf area in the upper canopy fluctuated widely but increased in the long term, in mid canopy was more or less maintained and in lowest canopy declined. Crops of developing flower buds present on uppermost branches delayed and/or reduced shoot growth. Foliage production occurred in all months of the year. There was a unimodal annual rhythm of growth rate reaching a maximum in summer and a minimum in winter. Variable water supply, however, influenced production to peak in spring, summer or autumn. No shoot growth occurs in E. maculata at Kioloa when daily mean temperature (averaged for weekly intervals) falls below c. 10½C in winter. An upper temperature limit for growth could not be defined. The species apparently lacks dormancy mechanisms. Shoot growth is 'opportunistic' and occurs whenever environmental conditions are favourable. Patterns of leaf production and leaf fall were variable but peaks showed a general synchrony. Leaf fall, however, tended to lag behind leaf production. Leaves of all ages were shed but main losses were from older cohorts. Some 49% (s.d.±18%) of new leaves were lost while still small or immature, mainly during periods of vigorous shoot growth or low water supply. Browse of immature foliage was light. Normal senescence and leaf fall accounted for almost the entire loss of mature foliage.

Canopy Dynamics of Eucalyptus maculata Hook. II. Canopy Leaf Area Balance

1984 ◽  
Vol 32 (4) ◽  
pp. 405 ◽  
Author(s):  
EW Pook
Keyword(s):  
Leaf Area ◽  
Basal Area ◽  
Leaf Fall ◽  
Leaf Production ◽  
Area Index ◽  
Sample Group ◽  
Sample Tree ◽  
Tree Canopies ◽  
Leaf Area Loss ◽  
Non Destructive

The leaf area balance of a regenerated stand of E. maculata was monitored for a period of 2� years on the basis of repetitive non-destructive measurements of production and loss of leaf area in sample branches of a group of trees representative of the forest. Leaf area loss measured in sample tree canopies was closely correlated with forest leaf fall (litter) and verified the phenological harmony between the sample group and the forest. Production and loss of leaf area from sample trees were scaled to the mean annual forest leaf fall to estimate production and loss at forest dimensions. Basal area of E. maculata tree bole was closely correlated with canopy leaf area. Basal area ratio (sample/forest) remained constant and was used to adjust sample group leaf area (determined by direct measurement) to forest dimensions for calculation of the forest leaf area balance. Basal area as an estimator of leaf area was insensitive to seasonal variations but provided a valuable reference datum. Leaf area index (LAI) of the eucalypt overstorey determined from basal area virtually remained unchanged. LAI of forest eucalypts estimated from the detailed leaf area balance fluctuated between 2.65 and 3.12. Maximum values of LAI were attained at the peak of growth seasons when rates of leaf production were high relative to leaf loss. Estimated annual production and loss of leaf area were not equal.

Corn and Velvetleaf (Abutilon theophrasti) Growth and Transpiration Efficiency under Varying Water Supply

Weed Science ◽  
2016 ◽  
Vol 64 (4) ◽  
pp. 596-604
Author(s):  
Logan G. Vaughn ◽  
Mark L. Bernards ◽  
Timothy J. Arkebauer ◽  
John L. Lindquist
Keyword(s):  
Water Supply ◽  
Soil Water ◽  
Leaf Area ◽  
Biomass Accumulation ◽  
Transpiration Efficiency ◽  
Plastic Bags ◽  
Comparative Response ◽  
Competitive Success ◽  
Daily Transpiration

The supply of soil resources is critical for the establishment and long-term competitive success of a plant species. Although there is considerable research on the effects of water supply on crop growth and productivity, there is little published research on the comparative response of crops and weeds to limiting soil water supply. The objective of this research was to determine the growth and transpiration efficiency of corn and velvetleaf at three levels of water supply. One corn or velvetleaf plant was grown in a large pot lined with plastic bags. When seedlings reached 10 cm, bags were sealed around the base of the plant, so the only water loss was from transpiration. Daily transpiration was measured by weighing the pots at the same time each day. The experiment was conducted in the fall of 2007 and in the spring of 2008. Four replicates of each species–water treatment were harvested periodically to determine biomass accumulation and leaf area. The relationship between cumulative aboveground biomass and water transpired was described using a linear function in which the slope defined the transpiration efficiency (TE). Corn TE was greater than velvetleaf TE in all treatments during both trials. In the fall trial, corn TE was 6.3 g kg–1, 47% greater than that of velvetleaf TE. In the spring trial, TEs of both species were lower overall, and corn TE increased with declining water supply. Corn produced more biomass and leaf area than velvetleaf did at all water-supply levels. Velvetleaf partitioned more biomass to roots compared with shoots during early growth than corn did. The ability of corn to generate more leaf area and its investment in a greater proportion of biomass into root growth at all levels of water supply may enable it to more-effectively avoid velvetleaf interference under all levels of soil-water supply.

scholarly journals A PROPOSED METHODOLOGY FOR THE CORRECTION OF THE LEAF AREA INDEX MEASURED WITH A CEPTOMETER FOR PINUS AND EUCALYPTUS FORESTS

2016 ◽  
Vol 40 (5) ◽  
pp. 845-854 ◽  
Author(s):  
Domingos Mendes Lopes ◽  
Nigel Walford ◽  
Helder Viana ◽  
Carlos Roberto Sette Junior
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Correction Factor ◽  
Basal Area ◽  
Allometric Equations ◽  
Nutrient Cycle ◽  
Area Index ◽  
Physiological Processes ◽  
The Difference ◽  
Non Destructive

ABSTRACT Leaf area index (LAI) is an important parameter controlling many biological and physiological processes associated with vegetation on the Earth's surface, such as photosynthesis, respiration, transpiration, carbon and nutrient cycle and rainfall interception. LAI can be measured indirectly by sunfleck ceptometers in an easy and non-destructive way but this practical methodology tends to underestimated when measured by these instruments. Trying to correct this underestimation, some previous studies heave proposed the multiplication of the observed LAI value by a constant correction factor. The assumption of this work is LAI obtained from the allometric equations are not so problematic and can be used as a reference LAI to develop a new methodology to correct the ceptometer one. This new methodology indicates that the bias (the difference between the ceptometer and the reference LAI) is estimated as a function of the basal area per unit ground area and that bias is summed to the measured value. This study has proved that while the measured Pinus LAI needs a correction, there is no need for that correction for the Eucalyptus LAI. However, even for this last specie the proposed methodology gives closer estimations to the real LAI values.

Long term and seasonal courses of leaf area index in a semi-arid forest plantation

2011 ◽  
Vol 151 (5) ◽  
pp. 565-574 ◽  
Author(s):  
Michael Sprintsin ◽  
S. Cohen ◽  
K. Maseyk ◽  
E. Rotenberg ◽  
J. Grünzweig ◽  
...  
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Forest Plantation ◽  
Area Index ◽  
Semi Arid

Effects of early defoliation on the seedling growth of subterranean clover

1992 ◽  
Vol 43 (3) ◽  
pp. 717
Author(s):  
RC Rossiter
Keyword(s):  
Linear Relationship ◽  
Leaf Area ◽  
Seedling Growth ◽  
Shoot Growth ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Relative Reduction ◽  
Insect Damage ◽  
Leaf Production ◽  
Plant Densities

Two experiments were conducted in an open-sided glass shelter at Perth during winter. Subterranean clover (Trifolium subterraneum, L.) seedlings were grown in shallow seed boxes at low plant densities, 2 4 and 2 0 plants/dm2. The effects of a single defoliation involving mainly the removal of cotyledons only, on shoot growth and leaf production were measured at harvest, c. 5 weeks after sowing. Total shoot dry weights were reduced by 15-30% when 40-60% of the leaf area was removed by single defoliations from days 7 to 19 after planting. However, the growth was reduced by almost 70% when both cotyledons were removed (days 7 to 9) before emergence of the unifoliate leaf, i.e. when all of the leaf area was removed. In general, the relative reduction in growth largely depended on the percentage of leaf area removed, rather than on time of removal. Defoliation also reduced the size of trifoliate leaves, and total numbers of trifoliate leaves at harvest. There was a linear relationship between total leaf numbers and shoot dry weights. In the field, these findings are probably of more relevance in terms of insect damage, especially from redlegged earth mites, than for grazing by sheep.

scholarly journals Leaf area estimation of medium size plants using optical metrology

2013 ◽  
Vol 17 (6) ◽  
pp. 595-601 ◽  
Author(s):  
Kleber M. Ribeiro ◽  
Roberto A. Braga ◽  
Myriane S. Scalco ◽  
Graham W. Horgan
Keyword(s):  
Leaf Area ◽  
Direct Methods ◽  
Optical Metrology ◽  
Medium Size ◽  
Coffee Plant ◽  
Indirect Methods ◽  
Area Index ◽  
The Subject ◽  
Non Destructive ◽  
Commercial Equipment

The total leaf area (TLA) estimation is an important feature of the crops and their assessment a challenge, since the direct methods of obtaining it are destructive and time consuming. Non-destructive methods have been explored to obtain the TLA by indirect approaches, in turn creating other features, as the leaf area index. The development of non-destructive technology to access the TLA of a plant has been the subject of much research, and the optical metrology is an promising approach. In this work, some indirect methods associated with optical approaches were evaluated as an alternative to obtain the TLA of the coffee plant. Commercial equipment were used, such as a camera with a fish eye lens and lux meters, associated to the sizes of the canopies were tested and compared to another non-destructive method and with methods proposed in the literature. The association between production and the TLA estimated was also evaluated. The results showed that the commercial equipment, generally used in forestry, was not the best approach in coffee plants, and that the methods related to the size and lux values of the plants were the best alternatives to estimate the TLA of the coffee plant.

scholarly journals EVALUATION OF SIMPLE HAND-HELD MECHANICAL SYSTEMS FOR HARVESTING TEA (CAMELLIA SINENSIS)

2006 ◽  
Vol 42 (2) ◽  
pp. 165-187 ◽  
Author(s):  
P. J. BURGESS ◽  
M. K. V. CARR ◽  
F. C. S. MIZAMBWA ◽  
D. J. NIXON ◽  
J. LUGUSI ◽  
...  
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Camellia Sinensis ◽  
Step Height ◽  
Area Index ◽  
Yield Increase ◽  
Coarse Material ◽  
Terminal Bud ◽  
The Mean

Over an eight-year period, harvesting methods based on simple mechanical aids (blade and shear) were evaluated against hand harvesting on mature morphologically contrasting tea clones in Southern Tanzania. The effects of shear step height (5–32 mm) and the harvest interval (1.8–4.2 phyllochrons) were also examined. Except in the year following pruning, large annual yields (5.7–7.9 t dry tea ha−1) were obtained by hand harvesting at intervals of two phyllochrons. For clones K35 (large shoots) and T207 (small shoots), the mean harvested shoot weights were equivalent to three unfurled leaves and a terminal bud. The proportions of broken shoots (40–48 %) and coarse material (4–6 %) were both relatively high. Using a blade resulted in similar yields to hand harvesting from K35 but larger yields from T207 (+13 %). The yield increase from clone T207 was associated with the harvest of more shoots and heavier shoots, smaller increases in canopy height, and a higher proportion (7–9 %) of coarse material compared to hand harvesting. On bushes, which had been harvested by hand for two years following pruning, using flat shears (no step) supported on the tea canopy resulted, over a three year period, in yields 8–14 % less than those obtained by hand harvesting and, for clone K35, a reduction in the leaf area index to below 5. The development of a larger leaf area index is made possible by adding a step to the shear. However, since annual yields were reduced by 40–50 kg ha−1 per mm increase in step height, the step should be the minimum necessary to maintain long-term bush productivity. As mean shoot weights following shear harvesting were about 13 % below those obtained by hand harvesting, there is scope, when using shears, to extend the harvest interval from 2 to 2.5 phyllochrons.

Inconsistencies of interannual variability and trends in long-term satellite leaf area index products

2017 ◽  
Vol 23 (10) ◽  
pp. 4133-4146 ◽  
Author(s):  
Chongya Jiang ◽  
Youngryel Ryu ◽  
Hongliang Fang ◽  
Ranga Myneni ◽  
Martin Claverie ◽  
...  
Keyword(s):  
Leaf Area Index ◽  
Interannual Variability ◽  
Leaf Area ◽  
Area Index
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