Effects Of Tree Height Research Articles

Effect of tree height and spraying methods on Diaphorina citri kuwayama endosymbionts in the context of Huanglongbing disease management in citrus orchards.

Huanglongbing (HLB) (caused by Candidatus Liberibacter asiaticus) is the most damaging disease of citrus around the world. This study investigated the effects of citrus tree height on Diaphorina citri Kuwayama mortality, endosymbiont responses, and HLB distribution. The results reveal that the age of citrus trees plays a significant role in psyllid mortality. Interestingly, the cumulative mean mortality (%) of psyllids over the seven-day observation period was higher (31.50±0.03) when four-year-old (501A1, 502A2, 501A3) citrus trees were sprayed with a US-SMART mechanical sprayer. In contrast, the psyllids mortality was 0.09±0.23 for the 13-year-old citrus trees (104A2, 104A3, 104C1) sprayed with a US-SMART mechanical sprayer and 9.10±0.05 for 13-year-old (502A2, 502B2, 502D1) citrus trees sprayed with a fixed US-SMART mechanical sprayer. Our findings also revealed that psyllids from both four- and 13-year-old citrus trees carried Candidatus Carsonella ruddii species and Wolbachia, the primary and secondary endosymbionts, respectively. Surprisingly, infection rates of these endosymbionts remained consistent across different age groups, as confirmed by quantitative polymerase chain reaction analysis. Furthermore, our study highlights the significance of tree height as a proxy for tree age in influencing HLB occurrence. Specifically, four-year-old citrus trees subjected to the US-SMART mechanical sprayer for citrus psyllid control demonstrated effective disease management compared to 13-year-old (104A2, 104A3, 104C1) citrus trees sprayed with US-SMART mechanicalsprayers. Additionally, the investigation explored the impact of tree height on HLB distribution. In four-year-old trees, no significant correlation between HLB disease and tree height was observed, potentially due to effective spray coverage with US-SMART mechanical sprayer. However, in 13-year-old (104A2, 104A3, 104C1) citrus tree sprayed with US-SMART mechanical sprayer, a positive correlation between tree height and HLB disease was evident. This research provides valuable insights into the complex interaction between citrus tree age, psyllid endosymbionts responses, and HLB distribution. These results emphasize effective HLB management strategies, especially in orchards with diverse tree age populations, ultimately contributing to the long-term sustainability of citrus cultivation. © 2023 Society of Chemical Industry.

Aboveground carbon stocks, woody and litter productivity along an elevational gradient in the Rwenzori Mountains, Uganda

AbstractMontane forests are characterized by high biodiversity, endemism, and strong elevational environmental gradients. The latter attribute makes them also suitable as a “natural laboratory” for studying the effects of environmental parameters on ecosystem functions. To provide better insight into the carbon cycle of Afromontane ecosystems, we used an elevational gradient approach to quantify carbon stocks, woody and litter productivity, and their constraining factors. Twenty plots were established, covering five elevations from Kibale Forest at 1250 m to 3000 m in the Rwenzori Mountains. Results revealed aboveground carbon stocks of between 185.4 ± 48.9 and 70.8 ± 18.6 Mg C ha−1 at 1250–1300 and 2700–3000 m, respectively. Aboveground carbon tended to decrease with elevation, but this trend was not significant. This was due to similarities in stem diameter combined with different effects of tree height and stem density. Similarly, woody productivity did not change with elevation, ranging from 8.3 ± 4.1 to 3.4 ± 1.5 Mg C ha−1 year−1 at 2500–2600 and 2700–3000 m, respectively. However, litter productivity decreased linearly by 0.14 ± 0.04 Mg C ha−1 year−1 per 100 m of elevation increase, ranging from 4.0 ± 0.7 Mg C ha−1 year−1 at 1750–1850 m to 1.2 Mg C ha−1 year−1 at 2700–3000 m. Topsoil physicochemical properties varied with elevation, but showed no significant relationship with carbon stocks and woody productivity. However, litter productivity increased with mean soil temperature, whereas it decreased with soil total nitrogen.

Disentangling the factors that shape bromeliad and ant communities in the canopies of cocoa agroforestry and preserved Atlantic Forest

AbstractIn tropical forest canopies, host tree characteristics shape epiphyte communities, and both host tree characteristics and epiphytes determine invertebrate communities, for example, ants. Tree height is among the factors most often mentioned as a strong predictor for both bromeliad and ant communities. However, many factors interact dynamically in shaping the tree–bromeliad–ant association. Here, we investigated the effects of the host tree and canopy structural characteristics on both bromeliads and ants. We sampled bromeliads on 180 trees and ants in 360 bromeliads living on a subset of 60 of those trees in a continuum of native forest fragments and agroforestry systems in the Atlantic Forest, a Brazilian biodiversity hotspot. We found that the host trees’ crown area had a positive effect on the abundance of bromeliads. Also, the introduced tree species had higher abundance of bromeliads than native tree species. Moreover, we found that the ant species composition was different between native and introduced trees. In addition, we observed a positive effect of the size of bromeliads and tree crown height on ant species richness on both bromeliad and tree scales, but there was no effect of tree height. Taken together, our findings highlight the importance of trees with large crowns for the maintenance of bromeliads, which are also associated with richer ant communities in both Atlantic Forest and agroforestry systems. These results emphasize the importance of trees with larger crowns for biodiversity conservation in both native forest fragments and agroforestry systems.Abstract in Portuguese is available with online material.

Tree diversity reduces pine infestation by mistletoe

The pattern that a given tree species suffers less damage when growing with heterospecific neighbors than amongst conspecific plants, i.e. associational resistance, is common for insect herbivores and many fungal pathogens. However, associational resistance to parasitic plants has never been tested in a replicated study. Using paired forest plots, we investigated whether tree diversity triggered associational resistance to a tree parasite, the European mistletoe Viscum album ssp. austriacum, by comparing pure stands of Scots pine (Pinus sylvestris) with mixtures of Scots pine and Maritime pine (Pinus pinaster) in northern Spain. Maritime pine, with 1.2% of trees being infested, was considered a non-host species in the study area. The infestation level of Scots pines was significantly higher in pure plots (45.1%) than in mixed plots of Scots pines and Maritime pines (25.4%). Our study is the first to quantify associational resistance to a plant parasite in mixed vs. pure forest stands and suggests that mechanisms proposed to explain associational resistance to insects and pathogens also apply to plant parasites. Scots pine trees that were taller than the surrounding trees had a higher infestation probability, in both pure and mixed stands. Scots pine trees growing in mixtures were slightly lower than Maritime pines, suggesting that associational resistance was partly driven by reduced relative tree height. However, the effect of plot type (pure vs. mixed) remained significant after the effect of tree height was accounted for, thus indicating that other factors also contributed to lower mistletoe infestation in mixed plots. In particular, the behavior of birds dispersing mistletoe seeds might differ in mixed vs. pure stands.

Termite Foraging on Plants of a Brazilian Savanna: the Effects of Tree Height

Termites play an important role as ecosystem engineers in many tropical environments, acting as herbivore-detritivore organisms and strongly influencing vegetation structure and composition by modifying soil properties, providing nutrients by recycling the organic matter, and direct feeding on plants, notably in the Cerrado (Savanna) of Brazil. To evaluate the intensity of termite foraging on Cerrado plants, we recorded plants higher than 25 cm, which exhibited termite activity along nine transects (2 x 50m), at the Estação Ecológica de Pirapitinga (EEP), in the State of Minas Gerais, Brazil. We recorded the height, basal area, and identified the species of each plant. Simultaneously, we used cellulose baits disposed at each 10 m along six transects of 100 m to sample termites in this area, which was protected from fire for at least 40 years. Twelve species of termites were recorded. Termite foraging on Cerrado plant species varied considerably and it was influenced by several factors including plant height and host species. Taller plants presented more termites than smaller plants, probably due to the amount of available resources (for nesting and feeding) for the termites.

Integrating multi-source remotely sensed datasets to examine the impact of tree height and pattern information on crimes in Milwaukee, Wisconsin

There have been a great number of debates about the impacts of trees on crimes: some researchers believed that trees are a crime facilitator because of the concealment provision for potential criminals, while others argued that they are a crime deterrent because of the increased surveillance possibility and the therapeutic effect on psychological fatigue. To better answer this question, this study incorporated detailed tree features by using multi-source remotely sensed data at a very high resolution into environmental criminology analysis across the entire City of Milwaukee. Trees were extracted from aerial photographs, and broken down into two categories based on their heights to consider the effects of tree height on view obstruction. By controlling for confounding socioeconomic variables, the relationship between crimes and a series of composition and configuration indicators of trees with different height were investigated by using global and local spatial regressions. Results from classic and spatial statistical techniques finds complicated relationship between crimes and trees, which can be summarized in two aspects. First, the mixed effects of trees can be observed among different crime types. Second, the trends of spatial nonstationarity of the composition and configuration of trees with different heights were observed across the entire study area. The study outcomes could provide reasonable implications for making appropriate policies for crime prevention through environmental design to strengthen neighborhoods and communities in a city.

Tree heights in the ring-formed years affect microfibril angles in the rings from juvenile to mature wood at breast height in hinoki trees (Chamaecyparis obtusa)

In this study, we examined past growth traits of hinoki (Chamaecyparis obtusa) trees by stem analysis, as well as growth traits in the years when the rings at breast height were formed. We tried to clarify the effects of growth traits in the ring-formed years on the wood properties of the rings from juvenile to mature wood. Height to diameter ratio (H/D) had a larger correlation coefficient in relation to stem stiffness than tree height or diameter at breast height (DBH). The longitudinal variation in stiffness of logs, except for first and top logs, in each tree was assumed to be constant with the height position in the trunk. Tree height in the ring-formed year had a significant negative effect on microfibril angle (MFA) near the pith, in transition wood, and in mature wood. DBH in the ring-formed year had a significant negative effect on density in mature wood. We concluded that the effects of tree height on MFA and of DBH on density produced the effect of H/D on stem stiffness of the trunk. Greater tree height in younger age may contribute to the improvement of juvenile wood properties.

Differences between height- and light-dependent changes in shoot traits in five deciduous tree species

The effects of tree height on shoot traits may in some cases differ in magnitude and direction from the effects of light. Nevertheless, general patterns of change in shoot traits in relation to variations in height and light have not so far been revealed. A comprehensive analysis of the differences between the effects of height and light on a range of leaf and shoot traits is important for the scaling of these traits to individual trees. We investigated the biomass allocation and structure of current-year shoots at the top of the crowns of five deciduous tree species in Japan. Height effect was investigated by comparing shoot traits among trees of different heights growing under a high light environment. The effects of light were examined by comparing saplings growing in high- and low-light environments. The effects of light were significant for most traits, while those of height were not significant for some traits. The magnitudes of the effects of light were larger than those of height for most traits related to biomass allocation. There was an extreme difference between the effects of height and light in the direction of change in the length of current-year shoots and in the number of standing leaves. The measures of both parameters increased with the increase in light, but decreased with the increase in tree height. Thus, the effects of height and light on diverse traits at the level of current-year shoots were not always similar. These results suggest that great care must be taken when scaling shoot traits from small trees to tall trees because the effects of height and light can be complex.

Effect of Tree Height and Girth on Gum Yield of Acacia senegal L. in Savanna Woodland of Nigeria

Parameters influencing gum yield such as tapping techniques and soil mineral elements had earlierbeen investigated while there is dearth of information on effect of morphological characteristics on gumyield. This study investigated effects of height and girth on yield of Acacia senegal L. in the naturalforests. Three heights and girth classes were purposely selected. Trees which heights and girth fell withinthose classes were selected randomly and tapped at constant height classes with varying girth classes.Exudates were collected, weighed and recorded according to height and girth class respectively.Descriptive and ANOVA results showed that when total tree height was lower than 2.0 m, gum yieldincreased as tree girth goes higher from 35 - 54cm (163.6 - 209.7g). Tree girth significantly affected gumyield (p≤0.05) and trees which total heights were lower than 2.0m (maximum of 1.95m) and girth higherthan 54cm (maximum of 65cm) produced the highest mean gum yield. Silvicultural practices that couldbring about increase in girth such as early pruning and re-spacing which is applicable to plantation treescould also be carried out on the natural forest trees to increase gum yield.Key words: Savanna woodland, Acacia senegal, Gum yield.

Experimental study on canopy interception using artificial Christmas trees to evaluate evaporation during rainfall and the effects of tree height and thinning

Experimental study on canopy interception using artificial Christmas trees to evaluate evaporation during rainfall and the effects of tree height and thinning

Effects of tree height on branch hydraulics, leaf structure and gas exchange in California redwoods

We examined changes in branch hydraulic, leaf structure and gas exchange properties in coast redwood (Sequoia sempervirens) and giant sequoia (Sequoiadendron giganteum) trees of different sizes. Leaf-specific hydraulic conductivity (k(L)) increased with height in S. sempervirens but not in S. giganteum, while xylem cavitation resistance increased with height in both species. Despite hydraulic adjustments, leaf mass per unit area (LMA) and leaf carbon isotope ratios (delta(13)C) increased, and maximum mass-based stomatal conductance (g(mass)) and photosynthesis (A(mass)) decreased with height in both species. As a result, both A(mass) and g(mass) were negatively correlated with branch hydraulic properties in S. sempervirens and uncorrelated in S. giganteum. In addition, A(mass) and g(mass) were negatively correlated with LMA in both species, which we attributed to the effects of decreasing leaf internal CO(2) conductance (g(i)). Species-level differences in wood density, LMA and area-based gas exchange capacity constrained other structural and physiological properties, with S. sempervirens exhibiting increased branch water transport efficiency and S. giganteum exhibiting increased leaf-level water-use efficiency with increasing height. Our results reveal different adaptive strategies for the two redwoods that help them compensate for constraints associated with growing taller, and reflect contrasting environmental conditions each species faces in its native habitat.

SOME ASPECTS OF WESTERN HEMLOCK AIR PERMEABILITY

Knowledge of the variability of fluid permeability of wood in general and of western hemlock in particular is of significant importance to the primary and secondary wood products processing industry of coastal British Columbia. For the purpose of this study, ten hemlock trees were randomly selected and specimens were prepared from three tree heights from each tree, namely, 1, 4 and 7 m. The air permeability of sapwood and heartwood in the longitudinal direction was measured using a dynamic method. Tracheid lengths were also obtained with a fiber quality analyzer and densities were measured by water displacement. The effect of tree height, tracheid length and density on the specific permeability of gross wood was then evaluated. The data revealed that height within the range measured has no effect on longitudinal permeability on heartwood whereas in sapwood the longitudinal permeability increases above 4 m of tree height. It was also found that longitudinal permeability was not significantly influenced by the tracheid length and wood density.

Impacts of timber harvesting on mammals, reptiles and nocturnal birds in native hardwood forests of East Gippsland, Victoria: a retrospective approach

Summary The occurrence of mammals, reptiles and nocturnal birds was assessed in a series of successional forest sites in East Gippsland, Victoria, Australia. A total of 63 sites, representing three major forest types (Wet, Damp and Lowland) and six different forest age classes (2, 5, 10, 18, 25 y after logging and unharvested), was sampled using a range of census techniques, with each combination of forest type and age class replicated. Totals of five nocturnal bird, twenty mammal and seven reptile species were recorded during this study. Key species were selected for subsequent analysis, representing three major faunal assemblages (arboreal mammals and nocturnal birds, ground-dwelling mammals, and heliothermic reptiles). Generalised linear modelling was used to investigate the relationship between the occurrence and diversity of species within each faunal assemblage with respect to the design variables (forest type and age class). To help explain any observed intra-age-class variation in animal occurrence or diversity, structural attributes were also analysed. The study highlights the importance of retained habitat attributes (old-growth legacies) within logged forest if wildlife conservation is to be a priority. The presence and abundance of large trees were the most important habitat variables for hollow-dependent fauna such as the southern boobook and yellow-bellied glider. The southern boobook and native rodents (Rattus spp.) were most likely to be found in unharvested forest, implying a negative impact of timber harvesting. The black wallaby was the only species to show a preference for younger age classes, an expected response from a species known to browse on regrowth seedlings. The mountain brushtail possum was more likely to be found on smaller coupes. Lowland forest supported the greatest species diversity of ground-dwelling mammals when only the design variables were considered. When effects of tree height and aspect were considered separately in the model, the trend was for greater species diversity in Damp forest. It is recommended that any increase in logging intensity in either Damp or Lowland forest should be balanced with suitable measures to protect sites of high conservation value. In the short term, no single species of heliothermic reptile appeared to be disadvantaged by logging operations. Spencer's skink may benefit from an increase in regrowth forest, provided large retained trees can be used as basking sites above the regrowth canopy. Species diversity of reptiles was affected adversely by harvesting in the Lowland forests and positively in the Wet forests. The protection of microhabitat attributes during timber harvesting operations may be one management strategy that would favour the long-term survival of forest reptiles in a logged area.

Patterns and levels of gene flow in Rhododendron metternichii var. hondoense revealed by microsatellite analysis.

Parentage analysis was conducted to elucidate the patterns and levels of gene flow in Rhododendron metternichii Sieb. et Zucc. var. hondoense Nakai in a 150 x 70 m quadrant in Hiroshima Prefecture, western Japan. The population of R. metternichii occurred as three subpopulations at the study site. Seventy seedlings were randomly collected from each of three 10 x 10 m plots (S1, S2, and S3) on the forest floor of each subpopulation (A1, A2, and A3). Almost all parents (93.8%) of the 70 seedlings were unambiguously identified by using 12 pairs of microsatellite markers. Within the quadrant, adult trees less than 5 m from the centre of the seedling bank (plots S1, S2, and S3) produced large numbers of seedlings. The effects of tree height and distance from the seedling bank on the relative fertilities of adult trees were highly variable among subpopulations because of the differences in population structure near the seedling bank: neither distance nor tree height had any significant effect in subpopulation A1; distance from the seedling bank had a significant effect in subpopulation A2; and tree height had a significant effect in subpopulation A3. Although gene flow within each subpopulation was highly restricted to less than 25 m and gene flow among the three subpopulations was extremely small (0-2%), long-distance gene flow from outside the quadrant reached 50%. This long-distance gene flow may be caused by a combination of topographical and vegetational heterogeneity, differences in flowering phenology, and genetic substructuring within subpopulations.

The effect of tree height on crown level stomatal conductance

ABSTRACTVariation in stomatal conductance is typically explained in relation to environmental conditions. However, tree height may also contribute to the variability in mean stomatal conductance. Mean canopy stomatal conductance of individual tree crowns (GSi) was estimated using sap flux measurements in Fagus sylvatica L., and the hypothesis that GSi decreases with tree height was tested. Over 13 d of the growing season during which soil moisture was not limiting, GSi decreased linearly with the natural logarithm of vapour pressure deficit (D), and increased exponentially to saturation with photosynthetic photon flux density (Qo). Under conditions of D= 1 kPa and saturating Qo, GSi decreased by approximately 60% with 30 m increase in tree height. Over the same range in height, sapwood‐to‐leaf area ratio (AS:AL) doubled. A simple hydraulic model explained the variation in GSi based on an inverse relationship with height, and a linear relationship with AS:AL. Thus, in F. sylvatica, adjustments in AS:AL partially compensate for the negative effect of increased flow‐path length on leaf conductance. Furthermore, because stomata with low conductance are less sensitive to D, gas exchange of tall trees is reduced less by high D. Despite these compensations, decreasing hydraulic conductance with tree height in F. sylvatica reduces carbon uptake through a corresponding decrease in stomatal conductance.

The effect of tree height and light availability on photosynthetic leaf traits of four neotropical species differing in shade tolerance

Abstract1. Light‐saturated rate of photosynthesis (Amax), nitrogen (N), chlorophyll (Chl) content and leaf mass per unit area (LMA) were measured in leaves of trees of different heights along a natural light gradient in a French Guiana rain forest. The following four species, arranged in order from most shade‐tolerant to pioneer, were studied: Duguetia surinamensis, Vouacapoua americana, Dicorynia guianensis and Goupia glabra. Light availability of trees was estimated using hemispherical photography.2. The pioneer species Goupia had the lowest LMA and leaf N on both an area and mass basis, whereas Duguetia had the highest values. In general, leaf variables of Vouacapoua and Dicorynia tended to be intermediates. Because Amax/area was similar among species, Goupia showed both a much higher light‐saturated photosynthetic nitrogen‐use efficiency (PNUEmax) and Amax/mass. Leaves of Vouacapoua demonstrated the greatest plasticity in Amax/area, particularly in small saplings.3. A distinction could be made between the effect of tree height and light availability on the structural, i.e. LMA, and photosynthetic leaf characteristics of all four species. The direction and magnitude of the variation in variables were similar among species.4. LMA was the key variable that mainly determined variation in the other leaf variables along tree height and light availability gradients, with the exception of changes in chlorophyll concentration. Amax/area, N/area, LMA and stomatal conductance to water vapour (gs) increased, whereas Chl/mass decreased, with both increasing tree height and canopy openness. Amax/mass, PNUEmax and Amax/Chl increased with increasing openness only. N/mass and Chl/area were independent of tree height and openness, except for small saplings of Goupia which had a much lower Chl/area.

Distribution Pattern and Sampling of Eggs of the Western Hemlock Looper (Lepidoptera: Geometridae) in Mature Western Hemlock Stands

An egg sampling study of the western hemlock looper, Lambdina fiscellaria lugubrosa (Hulst), was conducted in mature western hemlock stands from 1992 to 1994 in British Columbia, Canada. Egg density of the looper was homogenous within a tree crown, Suggesting that lower-crown sampling is effective for egg density estimation on the entire tree. Both the Taylor power law and the Iwao patchiness regression described egg distribution as aggregated. This aggregated distribution was further delineated as negative binomial distribution by chi-square test. Based on the Iwao model, the optimal sample size required to reach a predetermined precision level was calculated. To reduce egg-counting time, the relationship between mean egg density and proportion of lichen samples containing a specified number of eggs was established. The effect of tree height, diameter at breast height, crown width, crown length, and presence of heartrot on egg density was also examined. The results indicated no significant effect on egg density of these variables.

The Relationship between Seed Size and Establishment Conditions in Tropical Woody Plants

Two approaches were used to examine the relationship between seed size and typical establishment conditions in woody species of tropical rain forests. First we compared seed masses of 36 mature tropical forest tree species with differing light—gap requirements for establishment. The 14 species that become established beneath a closed canopy or in small gaps were found to have higher mean seed masses than the species that require large gaps. Though species were divided into two types of establishment requirements, plotting the mean seed masses produced a continuous unimodal distribution rather than a bimodal distribution, suggesting that either intermediate establishment conditions are most common in tropical rain forests or that other biotic or abiotic conditions confound the relationship between establishment conditions and seed mass. Second, we compared seed masses of 203 early and late successional woody plants in one Peruvian forest. Seed masses of mature forest species were found to be significantly larger than those of pioneer species, even when the effects of tree height, dispersal syndrome, and growth form were controlled for statistically. Thus, both analyses demonstrated a relationship between large seed size and establishment in shady, stable plant associations. Additional analysis of Peruvian forest data demonstrated that mammals tend to disperse larger seeds than birds do, trees tend to have larger seeds than vines, and taller plants of a given growth form tend to produce larger seeds than shorter plants of the same growth form.

Effect of Tree Height on Density and Survival Rate of the Western Spruce Budworm (Lepidoptera: Tortricidae): Instar IV to Adults

In the western spruce budworm, Choristoneura occidentalis, population densities of instar IV, residual pupae, and adults differed in at least one of three vertical crown strata (lower, mid, and upper) between trees 7 to 12m tall and trees 20 to 30 m tall. Survival rates in the trees of different sizes were indistinguishable. Hence, survival rates from instar IV to adults in the shorter trees were representative of those in the taller ones.