Canopy Dynamics of Eucalyptus maculata Hook .IV. Contrasting Responses to Two Severe Droughts

Pook, E. W.

doi:10.1071/bt9860001

Cited by 46 publications

(26 citation statements)

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“…Chloride concentrations of groundwater in these catchments ranged from 2000 to 5500 mg L^' (Biddiscombe et al 1985), compared with 2130 mg L~' used in my study. Moreover, the stress experienced by the mature trees during the drought that I monitored was probably less severe than would have been experienced by the same trees during an earlier drought, when rain-free periods lasted longer (Pook 1986).…”

Section: K)4 /mentioning

confidence: 99%

Dieback of rural eucalypts: the effect of stress on the nutritional quality of foliage

Landsberg

1990

Australian Journal of Ecology

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Canopy diebaek o/Euealyptus blakelyi trees is often associated with defoliation by insects: the foliage of trees with dieback is nutritionally superior for insects and ts more heavily damaged by them. I investigated whether differences in the nutritional quality of foliage were genetically determined, or caused by environmental stress. In a series of glasshouse experiments, with seedlings and grafted plants derived from dieback and healthy populations oj trees. I tested the injiucnce of deprivation of nutrients, drought, waterlogging, saline waterlogging and addition of excess phosphate, on the nutritional quality of foliage. Differences in the foliar properties of plants from different genetic .sources were not consistent with the differences between the source populations. Most of the environmental stresses applied caused a reduction in foliar quality (decreased water and nitrogen contents, and increased specific leaf weights). I hypothesize that the enhanced nutritional quality of the foliage of dieback trees is more likely to be a consequence of benign growing conditions (e.g. improved soil fertility) than of environmental stress. Field data for soil properties and the effect of drought on mature trees are consistent with this view.

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Section: K)4 /mentioning

confidence: 99%

Dieback of rural eucalypts: the effect of stress on the nutritional quality of foliage

Landsberg

1990

Australian Journal of Ecology

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“…These are proportional to a water stress integral (Myers 1988), which is the summation of predawn leaf water potential values over time. Long periods of water shortage are likely to affect the capacity of a canopy to utilise radiant energy by reducing L* -and hence APAR -through accelerated rates of leaf fall (Pook 1986, Linder et al 1987, or by reducing leaf growth and canopy development. Effects on canopy development are different for species that have determinate and indeterminate shoot growth.…”

Section: Physical and Physiological Basis Of £mentioning

confidence: 99%

Energy Conversion and Use in Forests: An Analysis of Forest Production in Terms of Radiation Utilisation Efficiency (ɛ)

Landsberg

Prince

Jarvis

et al. 1997

The Use of Remote Sensing in the Modeling of Forest Productivity

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The linear relationship between the photosynthetically active solar radiation (PAR) absorbed by forest canopies (APAR) and the production of dry mass by forests provides a simple, robust model with only one parameter for the estimation of forest production. The slope of the relationship is normally denoted E. The E model has been developed from plant production studies and is soundly based physiologically. It has also evolved from remote sensing studies. Although the relationship between APAR and canopy photosynthesis may be highly variable over short periods, it remains constant over longer periods, such as months or seasons.The effectiveness with which canopies convert energy into dry mass depends on environmental conditions such as temperature, water status and nutrition. Values of E derived experimentally, in terms of net primary production (NPP) and APAR, range from 2.8 g Mr 2 for agricultural crops to a low value of 0.2 g Mr 2 for tropical rainforests. Values for other forests tend to lie in the range of 1-2 g Mr 2 .Modifying factors with values between 0 and 1, dependent upon the availability of water in the soil, atmospheric vapour pressure deficits or nutrition, are used to account for the effects of these variables on E. If the modifiers are applied to E, the result is an estimate of potential E. Analysis of experimental results, therefore, should lead to the identification of optimum, unconstrained values of E, which may vary considerably less than the current experimental values.Since the proportion of incident energy absorbed by a plant canopy depends on the leaf area index (L*) of the canopy, good estimates of L* provide a sound basis for estimating APAR. Strong statistical relationships exist between reflectance ratios in the infrared, near-infrared and visible spectra, monitored from space, and L*, but these vary with vegetation type and surface conditions. More important are recent developments showing that the fraction of incoming energy absorbed by a canopy can be calculated directly from canopy reflectance properties measured from space. These allow direct application of the E model. As our knowledge of the factors causing variation in radiation utilisation by canopies improves, along with our capacity to The Use of Remote Sensing in the Modeling of Forest Productivityestimate environmental conditions and their modifying effects on radiation utilisation, it should be possible to use the £ model with remotely sensed data to estimate forest productivity over large areas.

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“…More insight into the causes of spatial and temporal variation in LAI can be expected from studies that investigate the variation in leaf area of a single tree species in response to environmental gradients. This variation has been examined for plantations of Eucalyptus species (Pook 1986;Battaglia et al 1998) and Pinus taeda (Hebert and Jack 1998), and for woodlands of Acacia koa (Harrington et al 1995;Ares and Fownes 1999). However, a comprehensive investigation in temperate broad-leaved forests is lacking.…”

Section: Introductionmentioning

confidence: 99%

Variation in leaf area index and stand leaf mass of European beech across gradients of soil acidity and precipitation

et al. 2006

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Leaf area index (LAI, the one-sided foliage area per unit ground surface area) is a key determinant of plant productivity which has a large influence on water and energy exchange between vegetation and the atmosphere. The variation in forest LAI across landscapes and environmental gradients and its causes are not sufficiently understood. We measured the LAI of European beech (Fagus sylvatica) by litter trapping in 23 closed, mature stands across gradients of rainfall and soil acidity or fertility. With a mean LAI of 7.4 m 2 m )2 (minimum: 5.6, maximum: 9.5 m 2 m )2 ), beech stands maintained a comparably high leaf area index with relatively small variation along steep environmental gradients. Contrary to expectation, decreasing water availability (rainfall gradient from 1030 to 520 mm yr )1 ) or increasing soil acidity (pH 3 -7) had no significant effect on LAI. Stand leaf mass (M l ) increased slightly with soil fertility (C/N ratio, base saturation). We regressed parameters of site water availability (rainfall), soil fertility or acidity (pH, base saturation, C/N ratio, exchangeable Mg and Al content), and stand structure (stand age and stem density) against LAI and M l in order to detect environmental controls of stand leaf area. Stand age was the most influential factor for both LAI and M l (negative relationship). Stem density and the base saturation of the soil affected M l significantly, but had a weak influence on LAI. We conclude that the leaf area index of beech is mainly under control of age-related physiological factors, whereas the influence of soil chemistry and rainfall is comparably low.

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Canopy Dynamics of Eucalyptus maculata Hook .IV. Contrasting Responses to Two Severe Droughts

Cited by 46 publications

References 0 publications

Dieback of rural eucalypts: the effect of stress on the nutritional quality of foliage

Dieback of rural eucalypts: the effect of stress on the nutritional quality of foliage

Energy Conversion and Use in Forests: An Analysis of Forest Production in Terms of Radiation Utilisation Efficiency (ɛ)

Variation in leaf area index and stand leaf mass of European beech across gradients of soil acidity and precipitation

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