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PubMed2002

Quantifying above- and below-ground growth responses of the western Australian oil mallee, Eucalyptus kochii subsp. plenissima, to contrasting decapitation regimes.

Resprouting in the oil mallee, Eucalyptus kochii Maiden & Blakely subsp. plenissima Gardner (Brooker), involves generation of new shoots from preformed meristematic foci on the lignotuber. Numbers of such foci escalated from 200 per lignotuber in trees aged 1 year to 3,000 on 4- to 5-year-old trees. Removal of shoot biomass by decapitation 5 cm above ground in summer (February) or spring (October) resulted in initiation of 140-170 new shoots, but approx. 400 shoots were induced to form if crops of new shoots were successively removed until sprouting ceased and rootstocks senesced. Initially, the new shoot biomass of regenerating coppices increased slowly and the root biomass failed to increase appreciably until 1.7-2.5 years after cutting. Newly cut trees showed loss of fine root biomass, and structural roots failed to secondarily thicken to the extent shown by uncut trees. After 2 years, the biomass of shoots of coppiced plants was only one-third that of uncut control trees and shoot:root dry mass ratios of coppiced plants were still low (1.5-2.0) compared with those of the controls (average ratio of 3.1). Spring cutting promoted quicker and greater biomass recovery than summer cutting. Starch in below-ground biomass fell quickly following decapitation and remained low for a 12-18 month period. Utilization of starch reserves in naturally regenerating coppices was estimated to provide only a small proportion of the dry matter accumulated in new shoots. Results are discussed in relation to their impact on coppicing ability of the species under natural conditions or when successively coppiced for shoot biomass production.

Australia↗
PubMed2002

Influence of litter and weather on seedling recruitment in a mixed oak-pine woodland.

The effects of regular litter removal and annual variation in temperature and precipitation on seedling recruitment of species differing in their seed size and mode of dispersal were studied in a 16-year (1984-1999) experiment in a mixed oak-pine wood in southern Poland. Litter was the most important factor in determining spatial variability in seedling recruitment, whereas differences in climatic conditions among years, especially temperature fluctuations in late winter and early spring, determined the temporal variability in seedling recruitment. Compared with control plots, significantly more new individuals of bryophytes and seedlings as well as a number of new species of vascular plants were noted in the litter-removal plots over the 16-year study. Litter strongly impeded seedling emergence of small-seeded species. The negative effect of litter on seedling recruitment of large-seeded species and the recruitment of new shoots in species growing clonally was much weaker. There was a significant positive correlation between the numbers of seedlings in the litter-removal and control plots and temperatures in January to March. In the litter-removal plots this mainly affected small-seeded species. Seedling recruitment was less consistently related to variation in precipitation. Positive relationships were found only between the number of seedlings of large-seeded species in the litter-removal plots and precipitation in July of the current year and in September of the previous year, and between the number of seedlings in the control plots and precipitation in September and November of the previous year.

Bryopsida↗
PubMed2006

Above- and below-ground biomass relationships across 1534 forested communities.

BACKGROUND AND AIMS: Prior work has shown that above- and below-ground dry biomass across individual plants scale in a near isometric manner across phyletically and ecologically diverse species. Allometric theory predicts that a similar isometric scaling relationship should hold true across diverse forest-types, regardless of vegetational composition. METHODS: To test this hypothesis, two compendia for forest-level above- and below-ground dry biomass per hectare (M(A) and M(R), respectively) were examined to test the hypothesis that M(A) vs. M(R) scales isometrically and in the same manner as reported for data from individual plants. Model Type II regression protocols were used to compare the numerical values of M(A) vs. M(R) scaling exponents (i.e. slopes of log-log linear relationships) for the combined data sets (n =1534), each of the two data sets, and data sorted into a total of 17 data subsets for community- and biome-types as well as communities dominated by angiosperms or conifers. KEY RESULTS: Among the 20 regressions examined, 15 had scaling exponents that were indistinguishable from that reported for M(A) vs. M(R) across individual plants. The isometric hypothesis could not be strictly rejected on statistical grounds; four of these 15 exponents had broad 95% confidence intervals resulting from small sample sizes. Significant variation was observed in the y-intercepts of the 20 regression curves, because of absolute differences in M(A) or M(R). CONCLUSIONS: The allometries of forest- and individual plant-level M(A) vs. M(R) relationships share strikingly similar scaling exponents, but differ because of considerable variation in y-intercepts. These results support prior allometric theory and provide boundary conditions for the scaling of M(A) and M(R).

Biomass↗
PubMed1994

Successful treatment of cutaneous leishmaniasis with allopurinol after failure of treatment with ketoconazole.

Treatment of persistent leishmaniasis with oral agents has received increasing attention, although the optimal agent for use in all settings has not been determined. This report describes a patient with persistent cutaneous infection due to Leishmania mexicana mexicana who apparently responded to therapy with allopurinol after treatment with a course of ketoconazole failed. In vitro testing of pre- and posttreatment isolates from the wound did not demonstrate the development of resistance to ketoconazole. To our knowledge, this is the first report that independently confirms the recently reported efficacy of allopurinol for treatment of leishmaniasis.

Adult↗
PubMed2006

Planning and implementing a community-based public health advocacy campaign: a transport case study from Australia.

Facilitating community action is a key goal of health promotion. This paper describes a public health advocacy framework. It then presents a case study of its application for planning community action by a community alliance concerned about increased heavy traffic on roads through a small regional city in the South West region of Western Australia. The case study illustrates defining the public health problem, the solution and the target for action; and the implementation of a comprehensive range of strategies including a media advocacy strategy to attract public attention, to reframe media messages, and to provide a policy alternative to government and industry. The campaign was evaluated in terms of process and outcomes, and was successful in putting pressure on key stakeholders and achieving the alliance's two main goals. The case study demonstrates the value of a well-planned campaign and including public health advocacy in public health practice, as an important strategy to facilitate the creation of healthy environments through healthy public policy.

Accidents, Traffic↗
PubMed2006

Towards landscape design guidelines for reducing Lyme disease risk.

BACKGROUND: Incidence of Lyme disease in the US continues to grow. Low-density development is also increasing in endemic regions, raising questions about the relationship between development pattern and disease. This study sought to model Lyme disease incidence rate using quantitative, practical metrics of regional landscape pattern. The objective was to progress towards the development of design guidelines that may help minimize known threats to human and environmental health. METHODS: Ecological analysis was used to accommodate the integral landscape variables under study. Case data derived from passive surveillance reports across 12 counties in the US state of Maryland during 1996-2000; 2,137 cases were spatially referenced to residential addresses. Major roads were used to delineate 514 landscape analysis units from 0.002 to 580 km(2). RESULTS: The parameter that explained the most variation in incidence rate was the percentage of land-cover edge represented by the adjacency of forest and herbaceous cover [R(2) = 0.75; rate ratio = 1.34 (1.26-1.43); P < 0.0001]. Also highly significant was the percentage of the landscape in forest cover (cumulative R(2) = 0.82), which exhibited a quadratic relationship with incidence rate. Modelled relationships applied throughout the range of landscape sizes. CONCLUSIONS: Results begin to provide quantitative landscape design parameters for reducing casual peridomestic contact with tick and host habitat. The final model suggests that clustered forest and herbaceous cover, as opposed to high forest-herbaceous interspersion, would minimize Lyme disease risk in low-density residential areas. Higher-density development that precludes a large percentage of forest-herbaceous edge would also limit exposure.

Ecosystem↗
PubMed2004

Assessing the use of butterflies as indicators of logging in Borneo at three taxonomic levels.

Logging is an issue of major conservation concern. Less than 5% of tropical forests are currently protected, and many of these are in so-called "paper parks." Many species may therefore depend on exploited forests, and management decisions concerning these forests will be a major determinant of their survival. An important aspect of forest management will entail the use of reliable, practical, and inexpensive indicator taxa to monitor exploitation. Here, butterflies are proposed as such indicators. Species, generic, and subfamily richness was significantly higher in logged than unlogged forest and community composition differed significantly at all three taxonomic levels (species, genus, and subfamily). Richness estimators were, furthermore, highly correlated among all three taxonomic levels. Significant individual indicator taxa were found at all three taxonomic levels, but the best overall taxa (highest indicator values) were found at the generic level and included the butterfly genera Ragadia and Paralaxita as indicators of unlogged forest and the genera Ypthima, Allotinus, and Athyma as indicators of logged forest. The use of genera instead of species presents a number of practical advantages. Identification is faster, easier, and more reliable. Genera can, furthermore, usually be identified "on the wing," thereby preventing accidental mortality due to capture.

Animals↗
PubMed2004

Long-term benefits to the growth of ponderosa pines from controlling southwestern pine tip moth (Lepidoptera: Tortricidae) and weeds.

The southwestern pine tip moth, Rhyacionia neomexicana (Dyar) (Lepidoptera: Tortricidae), is a native forest pest that attacks seedlings and saplings of ponderosa pine, Pinus ponderosa Dougl. ex Laws, in the southwestern United States. Repeated attacks can cause severe deformation of host trees and significant long-term growth loss. Alternatively, effective control of R. neomexicana, vegetative competition, or both in young pine plantations may increase survival and growth of trees for many years after treatments are applied. We test the null hypothesis that 4 yr of R. neomexicana and weed control with insecticide, weeding, and insecticide plus weeding would not have any residual effect on survival and growth of trees in ponderosa pine plantation in northern Arizona 14 yr post-treatment, when the trees were 18 yr old. Both insecticide and weeding treatment increased tree growth and reduced the incidence of southwestern pine tip moth damage compared with the control. However, weeding alone also significantly increased tree survival, whereas insecticide alone did not. The insecticide plus weeding treatment had the greatest tree growth and survival, and the lowest rate of tip moth damage. Based on these results, we rejected our null hypothesis and concluded that there were detectable increases in the survival and growth of ponderosa pines 14 yr after treatments applied to control R. neomexicana and weeds.

Animals↗
PubMed2005

Genetic structure inside a declining red oak community in old-growth forest.

Problems with oak regeneration have been documented in the last 50 years at numerous sites in the Midwestern United States. We applied nuclear microsatellites to examine the demographic and fine-scale spatial genetic structure of red oaks in two old-growth stands in Indiana. Oaks in one stand have declined in numbers over the past several decades whereas oaks in the other, smaller stand have increased. Large amounts of genetic variation were maintained within stands, and there was slight but significant differentiation among stands. There was significant but weak isolation by distance genetic structure within the large stand, likely reflecting family structure. No significant differences exist in allele frequencies or in levels of genetic diversity between cohorts that remain well represented within each stand, even between medium-sized adults and those antedating European settlement of the area. However, a virtual absence of smaller size classes in the forest interior of the large stand represents the early stages of a genetic bottleneck in what had been the core habitat of this stand. Whether future generations of this old-growth stand will retain the present genetic character depends on the oaks regenerating at the forest margins, absent any major changes in disturbance regimes. Similar demographic and genetic dynamics are likely occurring in a large number of remnant oak forests across the Midwest.

Forestry↗
PubMed1992

Risk factors for Lyme disease in a small rural community in northern California.

A 1-year prospective study of risk factors for seropositivity to and contraction of Lyme disease among members of a small rural community (population, approximately 150) was conducted in northwestern California in 1988-1989. The initial rate of seropositivity for Borrelia burgdorferi for 119 current or former residents ranged from 15 to 20% among three laboratories, with statistically significant interlaboratory agreement. Questionnaires were completed by 93 current residents at entry and 80 residents a year later to evaluate the association of serologic status with 20 categorical and 47 continuous variables. Seropositive subjects had resided in the study area about 2 years longer, were bitten by unspecified biting flies more often, and were less likely to have engaged in hiking than seronegative subjects. One of 59 seronegative subjects seroconverted a year later (annual incidence = 1.7%). The cumulative frequency of seropositivity for Lyme disease in the study population was > or = 24%. Of 83 subjects examined physically, 13 were diagnosed as having definite and 18 as having probable Lyme disease. The seropositivity rate was significantly higher (38.7%) among individuals with definite/probable Lyme disease than in asymptomatic subjects (13.5%). Subjects who were seronegative or free of Lyme disease reported nearly as many tick bites as subjects who were seropositive or had a diagnosis of the disease. Age, time spent outdoors in the fall multiplied by a clothing index, and woodcutting were significantly associated with Lyme disease in logistic regression analyses.

Adult↗
PubMed2001

Effects of thinning on wood production, leaf area index, transpiration and canopy interception of a plantation subject to drought.

We conducted thinning trials in a 5-year-old Eucalyptus globulus ssp. globulus Labill plantation near Warrenbayne, northeastern Victoria, Australia, where soil salinization and waterlogging are common, and assessed treatment effects on tree growth, water use and survival. Half-hectare plots were thinned from the original density of 1100 stems ha(-1) to densities of 800, 600 and 400 stems ha(-1), and stem diameter increment, leaf area index, transpiration, canopy interception and depth of tree water source monitored for 21 months. Two drought periods occurred during the study, rainfall was 30% below the long-term average and there was severe mortality in all three plots. Analysis of deuterium abundance in soil and xylem water indicated that the trees accessed water only from the top meter of the soil profile. Transpiration rates were higher in the most heavily thinned plot than in the least thinned plot, which underwent a reduction in basal area during the study. The most heavily thinned plot increased in basal area by 10% during the study. Edge trees had significantly greater diameters than trees from the middle of the plots.

Disasters↗
PubMed2001

Crown structure and leaf area index development in thinned and unthinned Eucalyptus nitens plantations.

The crown structure of Eucalyptus nitens (Deane & Maiden) Maiden 6 years after thinning, and the development of stand leaf area index both immediately and 6 years after thinning, were investigated. Thinning did not alter branch angle, branching density or the relationship between branch size and branch leaf area. However, larger branches were found in the lower crown of thinned trees and the increase in leaf area as a result of thinning occurred on the northern aspect of the crown. The vertical distribution of leaf area in unthinned trees was skewed toward the top of the crown and correlated with live crown ratio. The vertical distribution of leaf area in thinned trees tended to be less skewed and was unrelated to tree size or dominance. Leaf area index, as estimated from light interception measurements, increased at a constant rate soon after thinning regardless of residual stocking. In the longer term, residual stocking had a strong influence on leaf area increase per tree and was correlated with changes in crown length.

Eucalyptus↗
PubMed2001

Leaf area dynamics in a closed poplar plantation under free-air carbon dioxide enrichment.

Three Populus genotypes (P. alba L. (Clone 2AS-11), P. nigra L. (Clone Jean Pourtet) and P. x euramericana (Clone I-214)) growing in a managed, high-density forest plantation were exposed to free-air CO(2) enrichment (FACE) at CO(2) concentrations expected to occur in the future (550 ppm). Leaf area index (optical LAI), measured with a fish-eye-type plant canopy analyzer, was not significantly affected by FACE after canopy closure in the second growing season. However, when stands of similar size were compared, optical LAI and number of main stem leaves were reduced by FACE. Allometric relationships, which were established to scale-up leaf area to the stand level (allometric LAI), did not differ between the FACE and control plots. Allometric LAI increased in response to FACE, as a result of increased tree dimensions and increased individual leaf size. We postulate that, although FACE increased allometric LAI, FACE had no effect on optical LAI after canopy closure, because FACE caused increased shading and competition resulting in enhanced leaf fall or leaf turnover. Specific leaf area (SLA) was unaffected by FACE. Allometric relationships and relative responses to atmospheric CO(2) enrichment were genotype-dependent.

Carbon Dioxide↗
PubMed2001

Maturation, topophysis and other factors in relation to rooting in Larix.

We examined effects of mist quantity, topophysis (origin of cutting in the crown of 6-year-old trees), maturation state of the donor stock, and time of sticking on rooting and root system quality of cuttings representing five full-sib hybrid larch families obtained with Larix decidua Mill., L. laricina (du Roi) K. Koch, and L. kaempferi (Lamb.) Sarg. (Sieb. and Zucc.) Gord., as parents. Mist frequency, supplemental watering and family all had highly significant effects on percentage of cuttings rooting and root system quality. The high-frequency misting regime yielded both higher rooting percentages and higher quality root systems than the low-frequency regime without supplemental watering. Supplemental watering of the rooting medium in the low-frequency misting regime increased both percent rooting and root system quality to values comparable with those obtained by cuttings in the high-frequency misting regime. Rooting of cuttings from the top, middle and bottom whorls of 5-year-old plantation grown trees tended to decline with increasing height for three of the five families. Overall, height of cutting origin did not significantly affect rooting, but when analyzed separately, two families exhibited a significant decline in rooting toward the top of the trees. Age of donor ortet (ranging from 1 to 7 years) significantly affected both percent rooting and root system quality. Rooting percentages declined linearly with age, and root system quality declined more sharply than percent rooting. The relatively poor root system quality of cuttings from ortets older than 1 year was closely associated with plagiotropic growth. Softwood cuttings (stuck in mid-July) rooted better than hardwood cuttings (stuck in early September) across all families.

Forestry↗
PubMed2001

Ecosystem respiration in a young ponderosa pine plantation in the Sierra Nevada Mountains, California.

We estimated total ecosystem respiration from a ponderosa pine (Pinus ponderosa Dougl. ex Laws.) plantation in the Sierra Nevada Mountains near Georgetown, California, from June to October, 1998. We apportioned ecosystem respiration among heterotrophic, root, stem and foliage based on relationships for each component that considered microclimate and vegetation characteristics. We measured each respiration component at selected sampling points, and scaled the measurements up to the ecosystem based on modeled relationships. Over the study period, total mean ecosystem respiration was 5.7 +/- 1.3 mumol m-2 s-1 (based on daily mean), comprising about 67% from soil-surface CO2 efflux, 10% from stem and branch respiration and 23% from foliage respiration. Shrub leaves contributed about 24% to total foliage respiration, and current-year needles (1998 age class) accounted for 40% of total tree needle respiration. Root respiration accounted for 47% of soil-surface CO2 efflux. We conclude that ecosystem respiration can be estimated based on daily mean air and soil temperatures through exponential relationships with r2 values of 0.85 and 0.87, respectively. When based on both air and soil temperatures, about 91% of the variation in total ecosystem respiration could be explained by a linear regression.

Biomass↗
PubMed2001

Production efficiency of loblolly pine and sweetgum in response to four years of intensive management.

We tested the hypothesis that productivity of intensively managed loblolly pine (Pinus taeda L.) and sweetgum (Liquidambar styraciflua L.) stands is dependent not only on leaf area, but also on foliar photosynthetic rate. Effects of irrigation (irrigation treatment), irrigation with a fertilizer solution (fertigation treatment), and fertigation + pest control (loblolly pine only; fertigation + pest control treatment) on leaf physiology and growth were compared with control plots during the third and fourth growing seasons. Complete weed control was maintained on all plots. Aboveground net primary productivity of loblolly pine and sweetgum increased from 16.3 to 40.5 Mg ha(-1) and from 4.2 to 23.9 Mg ha(-1), respectively, in response to the most intensive treatment. Relative to the control treatment, neither fertigation of sweetgum nor fertigation + pest control of loblolly pine had a significant or consistent influence on foliar N concentration, quantum yield, carboxylation efficiency, net photosynthesis, stomatal conductance, or production efficiency (increment in woody biomass per unit leaf area). Irrigation increased predawn leaf water potential and photosynthesis of loblolly pine, but it had no effect on production efficiency. Leaf area was the predominant determinant of maximum productivity in these rapidly growing plantations.

Forestry↗
PubMed2002

Response of a mature Pinus laricio plantation to a three-year restriction of water supply: structural and functional acclimation to drought.

The response of mature forest stands to a reduction in water availability has received little attention. In particular, the extent to which a short-term reduction in gas exchange can be alleviated in the long-term by acclimation processes is not well understood. We studied the impact of a severe reduction in water availability on the water relations and growth of 35-year-old Pinus laricio Poiret. trees in a replicated experiment. Sapwood and needle increments, soil and tree water status, stand transpiration, xylem embolism and plant hydraulic architecture were monitored over a 3-year period in control and drought-treated plots. Needle length was reduced in drought-treated trees by 30, 19 and 29%, and sapwood increments by 50, 27 and 24% over the 3 years. Drought did not result in tree mortality or in extensive xylem embolism or foliage dieback. On the contrary, a conservative water-use strategy was observed, because minimum leaf water potentials did not differ between treatments or over the season. Plant hydraulic resistance was also unaffected by restricted water availability. Stand transpiration was strongly reduced by drought treatment over the summer, but not during the winter, despite significant differences in leaf area between control and drought-treated trees, implying higher transpiration rates per unit leaf area in the droughted plants. This suggests that water transport capacity, rather than the amount of leaf area, controlled stand transpiration, which is at variance with expectations based on experiments with seedlings and short-term experiments with mature trees.

Disasters↗
PubMed2002

Measured and predicted changes in tree and stand water use following high-intensity thinning of an 8-year-old Eucalyptus nitens plantation.

We investigated changes in the pattern of water use of an 8-year-old Eucalyptus nitens (Deane and Maiden) Maiden plantation soon after thinning. Sap flow sensors using heat pulse technology were deployed across three stands thinned to a final density of 100, 250 or 600 trees ha-1 plus an unthinned control (1250 trees ha-1). Changes in the relationship between tree size and daily water use were measured for 4 to 7 months after thinning. Thinning had no effect on sapwood water content. The increase in tree water use as a result of thinning was driven largely by significant changes in the radial pattern of sap velocity through the sapwood. The use of a canopy fraction factor in the Penman-Monteith equation to account for discontinuous canopies showed promise as a simple and effective method of scaling the model to predict transpiration from thinned plantations.

Circadian Rhythm↗