Influence of Insect Herbivory on the Decline of Black Box (Eucalyptus largiflorens)

1995 ◽  
Vol 43 (6) ◽  
pp. 555 ◽  
Author(s):  
C Stone ◽  
PE Bacon
Keyword(s):  
Leaf Shape ◽  
Insect Herbivory ◽  
Visual Assessment ◽  
Black Box ◽  
Crown Condition ◽  
Mature Trees ◽  
Trunk Diameter ◽  
Diameter Increment ◽  
Southern Central ◽  
Individual Trees

The contribution of insect herbivory to the canopy decline of Eucalyptus largiflorens F.Muell. (black box) was assessed on nine irrigated properties around Deniliquin in southern central New South Wales. Fully expanded leaves less than 1 year old were sampled from 36 mature trees in June 1993 and again in June 1994 after half the trees had been treated with a systemic insecticide in November 1993. Insect herbivory in treated trees fell significantly from 27 to 9%. It also fell, but to a lesser extent (28-19%, P < 0.05), in the untreated trees. The fall in insect herbivory in control trees corresponded to a decrease in rainfall in 1994 when the rainfall was 50% of that for 1993. There was a significant linear relationship between insect herbivory and trunk diameter increment in the untreated trees. There was no consistent relationship between insect herbivory and the visual assessment of crown condition. Although E. largiflorens is described as having both narrow adult and juvenile foliage, adjacent trees in this study differed significantly in their leaf length:breadth ratios. Canopies with a dominance of broader foliage had significantly higher levels of herbivory. Individual trees tended to replace foliage with leaves of similar morphology. It is suggested that this variation in leaf shape may be genetic rather than environmental. If so, landholders could select for trees with narrower foliage which may result in reduced impact of insect herbivory.

Distribution of the eucalypt-defoliating sawfly Perga affinis affinis (Hymenoptera)

1965 ◽  
Vol 13 (4) ◽  
pp. 593 ◽  
Author(s):  
PB Carne
Keyword(s):  
Field Experiments ◽  
Climatic Factors ◽  
Leaf Shape ◽  
Mature Trees ◽  
Leaf Production ◽  
Study Region ◽  
Sawfly Larvae ◽  
Litter Accumulation ◽  
Large Trees ◽  
Individual Trees

The distribution of the sawfly is discussed at several levels, ranging from that within a study region which comprised a substantial proportion of the known range of the insect, to that within the crowns of individual trees. A mosaic of areas was recognized within the region, each characterized by a degree of ecological uniformity and in which saivfly populations maintained relatively high or low levels of abundance during 6 yr of observation. The distribution of the insect is influenced strongly by climatic factors, the rainfall and temperature statistics for the critical period October-March for all areas in which it occurs being closely grouped. Such grouping is even more marked for those areas in which the sawfly was consistently most abundant. The cool wet limit of the sawfly's distribution coincides with that of a favoured host species, but the hot dry limit appears to be determined by the insect's susceptibility to desiccation. Although many naturally occurring and planted eucalypts will support sawfly larvae, persistent infestations were recorded only where one or more of three species grew - Eucalyptus blakelyi, E. camaldulensis, or E. melliodora. The sawfly is an inhabitant of river valley woodland, rarely becoming abundant in other situations and being absent from sclerophyll forest formations. Survival of the insect is greatly influenced by the ease with which it can penetrate into the soil for cocoon formation; it tends to be most abundant in areas of light soil, or where large trees provide a deep litter accumulation. The susceptibility of trees to infestation is influenced by seasonal production of new foliage. Those growing in sites where the water table is high, and whose leaf production is to a large extent independent of rainfall patterns, may be subject to chronic attack. Distribution between trees is affected by their leaf shape and texture, and by their history of previous defoliation. Small trees are particularly prone to attack, and infestation of mature trees is generally an indication of outbreak abundance of the insect. Similarly, marginally favoured species are attacked only when oviposition sites on more favoured trees are virtually saturated. Field experiments indicated that an observed contagious distribution of sawfly eggs in portions of the crowns of individual trees is not the result of overt gregariousness on the part of the females, but results from the attraction of the latter to foliage of certain physical characteristics and position on the tree.

The digestibility and the nitrogen, phosphorus and ash contents of the leaves of some Australian trees and shrubs

1973 ◽  
Vol 13 (62) ◽  
pp. 245 ◽  
Author(s):  
MN McLeod
Keyword(s):  
Significant Variation ◽  
Dry Matter ◽  
Mature Trees ◽  
Lower Range ◽  
Nitrogen Levels ◽  
Dry Matter Digestibility ◽  
Individual Trees ◽  
Trees And Shrubs ◽  
Nitrogen Phosphorus

The dry matter digestibility measured in vitro and the levels of nitrogen, phosphorus and ash were determined on the leaves from mature trees of twenty-one species growing in two arboreta in southeastern Queensland and known to be grazed by animals. Most of the leaf samples had digestibilities in the lower range (68 per cent samples < 50 per cent D.M.D.) and low ash levels (65 per cent samples < 7 per cent ash). Nitrogen levels were satisfactory (86 per cent samples in range 1.5-3.0 per cent N) but the level of phosphorus tended to be low (84 per cent samples < 0.20 per cent P). Statistically significant variation between individual trees and seasons was found with some species.

Genotypic diversity and clone size in old-growth populations of coast redwood (Sequoia sempervirens)

2000 ◽  
Vol 78 (11) ◽  
pp. 1408-1419 ◽  
Author(s):  
Deborah L Rogers
Keyword(s):  
Asexual Reproduction ◽  
Genotypic Diversity ◽  
Visual Assessment ◽  
Sequoia Sempervirens ◽  
Allozyme Diversity ◽  
Old Growth ◽  
Clone Size ◽  
Coast Redwood ◽  
Ring Structures ◽  
Individual Trees

Coast redwood (Sequoia sempervirens (D. Don) Endl.) has long-lived individual trees that can reproduce both sexually and asexually. Allozyme markers indicate that, in old-growth populations in northern California, 15-34% of clones are multistemmed. Of those, they have few stems per clone, and none are very spatially pervasive. There is much variety in the clonal configurations observed, including circular, linear, and (or) disjunct arrangements. Visual assessment is a poor predictor of clonal identity and fairy ring structures more often than not contain multiple genotypes. In this first allozyme study of coast redwood, high levels of genetic variation are observed, higher than those observed for most other western conifers. These levels are perhaps related to the species' hexaploid condition, ancient phylogenetic lineage, and historically broader natural range. There are also generally high levels of genotypic diversity. Upland sites, with more frequent and intense fires, do not differ significantly in genotypic diversity from the more mesic lowland sites. Population structure in coast redwood seems to resemble the classic pattern for many open-pollinated conifers: much diversity within and little among populations. However, this is not a rangewide study. The current levels and structure of genetic and genotypic diversity in old-growth populations suggests episodic recruitment. The long-lived nature of individual stems and the capacity for asexual reproduction may allow clones to exist indefinitely, thus challenging some of the generalizations in evolutionary theory that are based on sexually reproducing species.Key words: clones, asexual reproduction, allozyme diversity, conifer, gymnosperm, polyploid.

Incorporating intertree competition into an ecosystem model

1995 ◽  
Vol 25 (3) ◽  
pp. 413-424 ◽  
Author(s):  
R.L. Korol ◽  
S.W. Running ◽  
K.S. Milner
Keyword(s):  
Process Model ◽  
Basal Area ◽  
Stand Density ◽  
Tree Height ◽  
Ecosystem Model ◽  
Growth And Yield ◽  
Maintenance Respiration ◽  
Tree Diameter ◽  
Diameter Increment ◽  
Individual Trees

Current research suggests that projected climate change may influence the growth of individual trees. Therefore, growth and yield models that can respond to potential changes in climate must be developed, TREE-BGC, a variant of the ecosystem process model FOREST-BGC, calculates the cycling of carbon, water, and nitrogen in and through forested ecosystems. TREE-BGC allocates stand-level estimates of photosynthesis to "each tree using a competition algorithm that incorporates tree height, relative radiation-use efficiency, and absorbed photosynthetically active radiation, TREE-BGC simulated the growth of trees grown in a dense and an open stand of interior Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) near Kamloops, B.C. The competition algorithm dynamically allocated stand estimates of photosynthesis to individual trees, and the trees were grown using an allometric relationship between biomass increment and height and diameter increment. Asymptotic height growth and the changes in the height–diameter relationship with competition were also incorporated in the model algorithms. Sapwood and phloem volume were used to calculate maintenance respiration. Predicted reductions in diameter growth with stand density were similar to those observed in the study stands. Although the carbon balance of individual trees was not tested, simulated tree diameter increments and height increments were correlated with the actual measurements of tree diameter increment (r2 = 0.89) and tree height increment (r2 = 0.78) for the 5-year period (n = 352). Although the model did not work well with trees that had diameters <5 cm, the model would be appropriate for a user who required an accuracy of ± 0.03 m3•ha−1 for volume, ± 0.02 m2•ha−1 for basal area, or ± 0.4 m for tree height over a 5-year period.

scholarly journals RELATIONSHIPS OF LEAF AREA AND TRUNK DIAMETER OF APPLE TREES AFFECTED BY ROOTSTOCK AN D CULTIVAR

HortScience ◽  
1992 ◽  
Vol 27 (11) ◽  
pp. 1169c-1169
Author(s):  
Curt R. Rom ◽  
Renae E. Moran
Keyword(s):  
Leaf Area ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Mature Trees ◽  
Apple Trees ◽  
Cross Sectional ◽  
Trunk Diameter ◽  
Yield Efficiency ◽  
Linear Relationships ◽  
Old Trees

Trunk cross-sectional area (TCA) has been used to estimate leaf area (LA) and yield efficiency but variation in LA and TCA relationships have been unexplored. LA and TCA of 10-yr-old 'Starkspur Supreme Delicious' on 9 rootstocks (STKs) were measured in 1989. LA and TCA of 2-yr-old trees of 3 cultivars (CVs) on 5 STKs were measured in 1991. Regression of LA and TCA was performed for each CV, STK and each CV/STK. On mature trees, LA varied significantly with STK. The number and LA of shoot leaves (LVS) and spur LVS varied with STK but the % of total was not significantly different (approx. 52% spur LVS). The relationships of LA and TCA were linear for mature (r2=.94) and young (r2=.44) trees. On young trees, TCA varied with CV, but LA did not. Both LA and TCA were significantly different among STKs. The linear relationships of LA and TCA had unique intercepts with each CV, STK and CV/STK combination but slopes were not significantly different. Leaf area of Jonagold' and 'Gala' tended to increase more with increasing TCA than 'Empire'.

scholarly journals Water Use and Stomatal Behavior of Sweetgum (Liquidambar styraciflua) Relative to Reference Evapotranspiration in Three Contrasting Regions

HortScience ◽  
2004 ◽  
Vol 39 (4) ◽  
pp. 764C-764
Author(s):  
Roger Kjelgren* ◽  
Thayne Montague ◽  
Richard Beeson
Keyword(s):  
Water Use ◽  
Reference Evapotranspiration ◽  
Regional Climate ◽  
Liquidambar Styraciflua ◽  
Trunk Diameter ◽  
Dry Down ◽  
High Vapor ◽  
Tree Leaf ◽  
Individual Trees ◽  
Total Tree

We investigated water use and a water needs index multiplier relative to reference evapotranspiration for a sweetgum cultivar (Liquidambar styraciflua `Moraine') in Logan, Utah, Lubbock, Texas, and Orlando Fla. Three individual trees with ≈80-mm trunk diameter, were potted in to large containers with organic media at each location. Sweetgum water use (Tsw) was measured over the season at each location with load cells and dataloggers, concurrent with measurement of reference evapotranspiration (ETo) from adjacent weather stations. Dawn-to-dusk stomatal conductance (Gs) was measured several times during the season at all locations. Trees were watered daily. At the end of the season, total tree leaf area was collected and used to normalize volumetric water use data to depth units. Tsw was highest in Florida, up to 4 mm/day, as was maximum daily Gs. Tsw only reached 2.5 mm/day in Texas and Utah due in part to stomatal sensitivity to high vapor pressure deficits that moderated transpiration. There was no relationship between Tsw and ETo at ETo levels above 4 mm/day in Texas and Utah, resulting in substantial scatter in the water needs index multiplier relative to ETo that centered on 0.3 in Texas and 0.4 in Utah. Tsw in Florida showed an upper boundary relationship with ETo, under which it varied considerably, resulting in a values relative to ETo centered on 0.6. During a partial dry down in Utah, morning Gs was unaffected while afternoon Gs declined progressively under mild water stress, resulting multiplier values of 0.15-2. The study shows that regional climate affects tree water use independent of effects measured in ETo, increasing the uncertainty of sweetgum water use estimated as a function of ETo.

The relationship between electrical resistance and severity of decline symptoms in Acersaccharum

1977 ◽  
Vol 7 (3) ◽  
pp. 469-475 ◽  
Author(s):  
Dennis Newbanks ◽  
Terry A. Tattar
Keyword(s):  
Electrical Resistance ◽  
Callus Tissue ◽  
Measurement Techniques ◽  
Crown Condition ◽  
Increment Core ◽  
Sugar Maples ◽  
Time Of Year ◽  
Urban Campus ◽  
Individual Trees ◽  
The Relationship

Electrical resistance (ER) measurements of the xylem–cambium area were affected by time of year, air temperature, tree diameter, species, bark blemishes, callus tissue, decay, and measurement techniques. Our results indicate that in urban sugar maples there was no statistically significant correlation between ER and tree response to physiologic stress, as measured by visual crown classification (based on the severity of decline symptoms) and by increment core data. Trees in a non-urban, campus setting showed a significant correlation between electrical resistance and visual crown symptoms (r = 0.61). Trees with intermediate crown-condition ratings had the highest average ER, and on the basis of ER, individual trees could not be placed into stress-response categories because of large variations in ER within each crown-condition class. No significant correlation was found between ER and applied physiologic stresses in nursery-grown sugar maples.

Tree population dynamics at Kade, Ghana (1968-1982)

1987 ◽  
Vol 3 (4) ◽  
pp. 331-345 ◽  
Author(s):  
M. D. Swaine ◽  
J. B. Hall ◽  
I. J. Alexander
Keyword(s):  
Growth Rates ◽  
Deciduous Forest ◽  
Total Mortality ◽  
Basal Area ◽  
Forest Composition ◽  
Strongly Correlated ◽  
Diameter Increment ◽  
Tree Population ◽  
Individual Trees ◽  
Diameter Classes

ABSTRACTChanges in two 1-ha samples of Moist Semi-deciduous forest at Kade, Ghana are described for 14 years from 1968 to 1982. Density of trees ≥10 cm dbh was 552 ± 13 ha−1and the basal area was 30.85 ± 1.38 m2 ha−1, and showed little variation over the study period: diameter class distributions did not change significantly. There were 120 species of tree ≥10 cm dbh, including seven immigrants and seven emigrants.Mortality did not differ significantly between diameter classes, but was significantly greater amongst trees showing negative diameter increment. Total mortality for the 2 ha over the 12-year period 1970–1982 was 216 trees (1.77% yr−l) and was balanced by a recruitment of 212 trees to the measured population.Growth rates were highly variable within species populations. Overall, bigger trees tended to have higher growth rates. Successive diameter increments in individual trees were strongly correlated, and were still significant after 10 years. These results support the idea that the faster-growing individuals are the more likely to reach the canopy.Estimates of the age of trees by summing mean passage times for successive diameter classes is shown to be misleading because similar calculations using only the fastest-growing trees gives substantially lower estimated ages.Although overall forest composition showed little change, a few species showed small but significant imbalance between recruitment and mortality. Recruitment and mortality differed significantly from overall rates for some species, but only markedly for the megaphanerophyte Celtis mildbraedii which had lower than average rates for both mortality and recruitment.

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