Health Status Of Trees Research Articles

Long and short term population dynamics of acacia trees via remote sensing and spatial analysis: Case study in the southern Negev Desert

Monitoring vegetation dynamics in hyper-arid zones is important because any decrease in the already sparse vegetation cover in these areas could considerably affect the entire ecosystem. The new generation of high spatial resolution satellite (HSR) sensors is suitable for monitoring trees in arid regions because of the distinct and separate objects that trees represent in these environments. The main limitation of modern HSR sensors is the lack of a historical archive that would otherwise enable meaningful landscape change detection, especially in arid regions where tree population dynamics are naturally very slow. This study uses spatial analysis to gain information regarding the long- and short-term dynamic processes affecting the acacia tree population in Wadi Ktora, in the southern Arava Valley, Israel. The data is extracted from a single HSR aerial photograph composed of three spectral bands in the visible and infrared spectrum (green, red, and near infrared).A map of individual acacia trees that is extracted from a colour infrared aerial photograph of Wadi Ktora from 2010 enables the examination of spatial distribution patterns for both tree size and foliage health. Tree size distribution is used as an indicator of long-term (decades) hydrologic spatial processes affecting the acacia population. The tree health distribution is used as an indicator for short-term (months to a few years) hydrologic spatial processes, such as the paths of recent flash floods events. Comparing the distributions of tree size and normalized difference vegetation index (NDVI) enables differentiation between the long-term and short-term processes that brought the population to its present state.Using spatial statistic grouping, the distribution of the trees in the wadi (ephemeral stream) is divided into three distinct categories: (1) large trees with high NDVI values, (2) large trees with low NDVI values, and (3) small trees with medium NDVI values. Using the resulting classification, we divided the wadi into three sections, each representing a unique combination of long- and short-term hydrologic processes affecting the acacia trees. We suggest that the lack of spatial correlation between tree size and health status is a result of spatio-temporal changes in the water supply.

Structural and functional differences in the belowground compartment of healthy and declining beech trees

Functional studies of tree decline have mainly focused on process inside the plant showing possible alterations of carbon transport, storage and hydraulic functions. However, the processes occurring at the plant-soil interface have been seldom investigated. Our objective is to examine carbon functional alterations in the belowground compartment in the case of a long term beech decline. Soil and nutrient content profiles were characterized under five healthy and five declining trees. Seasonal root growth and rhizodeposition were characterized using, ingrowth cores, and microbial biomass combined with soluble carbon organic content, respectively. Podzolisation associated with soil acidification and deficiencies in Ca, Mg and Mn were observed in the soil under declining trees, but not under healthy trees. Spring fine root growth was higher in declining trees than in healthy trees but there were only minor differences concerning rhizodeposition proxies. In our study, we showed that the tree health status is associated to a marked heterogeneity of soil characteristics. Podzolisation close to declining trees leads to a local mineral deficiency which probably stimulates their fine root growth but without altering their flux of carbon exudates.

Isolation studies reveal a shift in the cultivable microbiome of oak affected with Acute Oak Decline

Acute Oak Decline is a syndrome within the Oak Decline complex in Britain. Profuse stem bleeding and larval galleries of the native buprestid, Agrilus biguttatus characterize the disease. A systematic study comparing healthy with diseased trees was undertaken. This work reports the result of isolations from healthy trees, diseased and non-symptomatic tissue within AOD affected trees, at five sites in England. Bacteria and fungi were identified using the DNA gyrase B gene, or ITS 1 sequencing. A significantly higher proportion of diseased tissues (82%) yielded more bacteria than either healthy (18%) or non-symptomatic tissue in diseased trees (33%). Overall bacterial community compositions varied at each site, but significant similarities were evident in diseased tissues at all sites. Enterobacteriaceae dominated in diseased trees whereas Pseudomonadaceae dominated healthy trees. Significant associations between diseased tissues and certain bacterial species occurred, implying that the cause of tissue necrosis was not due to random microbiota. Brenneria goodwinii and Gibbsiella quercinecans were key species consistently isolated from diseased tissue; Rahnella victoriana and an un-named Pseudomonas taxon were also frequently isolated from both healthy and diseased trees. Most fungi isolated were from the outer bark and had no significant association with tree health status. It was concluded that there was a shift in the cultivatable bacterial microbiome of diseased trees, with Enterobacteriaceae strongly represented in symptomatic but not healthy tissues. No single species dominated the isolations from diseased tissues and the tissue degradation in AOD is therefore likely to have a polymicrobial cause.

Status Kesehatan Pohon Pada Jalur Hijau Dan Halaman Parkir Universitas Lampung

Campus of University Lampung was one of the urban green open spaces which has ecological, social, cultural, and aesthetic. The frequency of broken branches and fallen trees indicated that many of trees were in unfavorable conditions. Identification of the tree health status was an important effort in order to manage trees properly, according to silviculture theorems. The study aimed (1) to figure out the trees health status in the green line along the street and parking area in University of Lampung, (2) figure out pests and diseases and also and human disturbance that cause the tree damage. The Forest Health Monitoring (FHM) method was employed to identifie the tree health status. The result of research showed that, majority (92.29%) of trees in the green line and the parking area of Lampung University were in health condition, and only a small percentage (7,81%) were identified in light damaged, medium demaged, and hard damaged. Generally, there were nine types of tree damage that most found. Those damage were discoloration of leaves (10.48%), open wounds (10.38%), fruiting bodies (4.11%), cancer (3.80%), epifit (2.26%), leaf buds damage (1.23%), fractures branches/trunks (1.54%), branchis (0.92%), and resinosis (0.51%). Keywords: Forest Health Monitoring (FHM), urban forest of Unila, tree health, plant diseases

Are climatic factors responsible for the process of oak decline in Poland?

Oak decline, a complex process leading to increased mortality of this species, has been observed in Europe for many years. Previous studies suggest that climate conditions, especially drought, may be one of the most important factors that trigger this phenomenon. The paper investigates the radial growth and wood anatomy features of pedunculate oak (Quercus robur) trees of various health status as well as their response to climate conditions. Wood samples including all annual increments were taken at two sites (western and central Poland, 15 trees each). Based on the crown defoliation level, three health groups (healthy, weakened and dead oaks) were distinguished. Cross-sections were prepared with sliding microtome and Cell P image analysis software was used for the measurements. Tree-ring width (TRW), earlywood vessels density (VDen) and non-weighted vessels diameter (VD) were determined and correlated with mean monthly values of temperature, precipitation, vapour pressure, and Palmer Drought Severity Index (PDSI). Radial increment and anatomical parameters were significantly higher for the healthy oaks than for the weakened and the dead trees. TRW showed smaller dependence on climate than analysed anatomical attributes. No obvious pattern of relationship was found between oak radial growth and climate regarding tree health status. Our results revealed that the drought has a weak impact on the process of oak decline on investigated sites in Poland.

Can we predict Sphaeropsis sapinea outbreak by monitoring fungal diversity in austrian pine plantations?

Fungal diversity plays an important role in forest ecosystems stability as well in the health status of mycorrhizal forest trees. At research area in Istria, Croatia, pathogenic fungus Sphaeropsis tip blight (Sphaeropsis sapinea (Fr.) Dyko et Sutton) caused substantial damage in Austrian pine (Pinus nigra J. F. Arnold) plantations during the last decades. This research continues on previous done in Austrian pine plantations on predisposition to S. sapinea infections, where site and stress conditions were determined as key factors, but also, the ectomycorrhizal (ECM) fungi were confirmed as biological indicators of the health status in selected plantations. We analyzed fungal diversity of Austrian pine plantations to determine the dependence of species richness and its diversity index, both for total and ECM species only, in relation to S. sapinea infection rate and crown transparency of selected trees. Fungal samples were collected during 2013 at nine permanent research plots in autumn season. Their total and ECM species richness and diversity index were correlated to Sphaeropsis tip blight infection level and crown transparency. Our results did not confirm the hypothesis that Austrian pine plantations with higher total species richness and its diversity index are more resistant to S. sapinea infection nor to crown transparency. Oppositely, ectomycorrhizal species richness and its diversity index might be used as good biological indicators of S. sapinea presence and crown transparency of studied plantations.

Popolamenti marginali di faggio e cambiamenti climatici in Sicilia: criticità ed effetti dell'applicazione di pratiche selvicolturali tradizionali non-sostenibili al variare delle condizioni micro-stazionali

In Sicily where the southernmost beech forests of Europe are located, beech stands show peculiar ecological, characters. The ecological marginality of these forests is particularly evident in the fragmented and isolated beech stands, near the timberline and/or located on less favourable topographic conditions. In this study we analyzed stand-structural parameters and tree health comparing recently coppice felled beech stands and control plots. Additionally, these aspects have been related also to the local topographic gradient and the cover fragmentation. Results clearly show a pronounced tree health reduction (more crown and bark damages, higher percentage of dead trees, lower seedling density) related to cut coppice, as far as to marginal topographic condition (on ridges and slopes) and stand-cover fragmentation (in clearing/border trees). The clear decreased tree health may lays an increasing future threat for these multi-marginal (for latitude, topography and cover fragmentation) beech stands. In addition, our results could also support the hypothesis that, although the silviculture effects originated by the human actions is quite evident in the two compared groups (coppice-cut and control), hastening the tree health reduction, a general climate change effect is going on these marginal beech stands. The reduced tree health status also in control plots seems to show this way.

Effects of air pollution and climatic factors on Norway spruce forests in the Orlické hory Mts. (Czech Republic), 1979–2014

The area of the Orlicke hory Mts. has been characterised by decline and disturbances of Norway spruce (Picea abies/L./Karst.) stands since the 1980s. Currently, only three permanent research plots have been preserved from the original sixteen established plots in this region. In the present study, the health status, as indicated by defoliation, mortality, and stem radial growth, was studied in the peaty and climax spruce ecosystems in the upper elevations of the mountains from 1979 to 2014. This health status was correlated with ambient air pollution (SO2) as well as climate factors (temperature and precipitation). The health status of individual trees on the plots was determined by evaluation of the foliage status, and tree vitality was evaluated by measuring stem radial growth increment. Stress factor analysis showed that high air pollutant concentrations predisposed Norway spruce to stress from climatic events (drought, temperature changes), leading to forest decline. The most serious damage can be attributed to the combination of chemical and climatic stress. Stands with lowered vitality were attacked by secondary biotic pests (particularly bark beetle), resulting in rapid tree mortality. The damage process is marked not only by higher mortality, but also by chlorosis and necrosis of the needles. The stabilised trend in health status of the spruce stands was registered since approximately 1990s. In terms of climatic factors, the weather in June had the most visible influence on radial increment. Low temperatures and high precipitation were the limiting factors for radial growth in studied mountain area.

Structure, development and health status of spruce forests affected by air pollution in the western Krkonoše Mts. in 1979–2014

Abstract The structure and health status of waterlogged or peaty spruce (Picea abies [L.] Karst.) forests in the summit parts of the Krkonoše Mts. in the Czech Republic were studied in 1979–2014. The objective was to evaluate the stand structure, dead wood, trend of the health status and productivity on four permanent research plots (PRP) in relation to air pollution (SO2 and NOx concentrations) and climatic conditions (temperatures and precipitation amounts). Stand structure was evaluated on the base of the measured parameters of individual trees on PRP. The health status of trees was evaluated according to foliage, and their vitality was assessed according to their radial growth documented by dendrochronological analyses. The radial growth was negatively correlated with SO2 and NOx concentrations. Stand dynamics during the observation period was characterised by increased tree mortality, the presence of dead wood and reduction of stand density from 1983 to 1992, while the most severe impairment of health status and stand stability occurred in 1982–1987. The foliage mass of living trees has been gradually increasing since 1988, but no pronounced improvement of tree vitality was documented after the decrease in SO2 concentration. However, particularly physiologically weakened spruce trees were attacked by the European spruce bark beetle (Ips typographus). The process of forest damage is manifested not only by foliage reduction but also by symptoms of various necroses on the assimilatory organs. In terms of climatic data, the weather in April had the most important effect on radial growth. Diameter increment showed positive statistically significant correlation with temperature in growing season, but the precipitation effect was low.

The Importance of CIR Aerial Imagery in Inventory, Monitoring and Predicting Forest Condition

Background and Purpose: The main goal of this paper was to highlight the importance of colour infrared (CIR) aerial photographs for efficient inventory, monitoring and predicting the health status of forests in changed site conditions. CIR aerial photographs from two aerial surveys conducted in 1989 and 2008 were used to identify and analyze the damage in lowland pedunculated oak (Quercus robur L.) forests during each period, as well as to obtain a dieback trend in the observed period. Material and Methods: The research was conducted in lowland pedunculated oak forests of Josip Kozarac management unit. CIR aerial photographs (1989) of the research area were taken with a classical camera, while aerial images in 2008 were taken with a digital camera and then converted from digital to analogue form (contact copy - photograph) in order to perform photointerpretation with a SOKKIA MS27 Carl ZEISS Jena mirror stereoscope, magnified by 8x. The health status of particular trees (crowns) was assessed by means of photointerpretation keys in a stereomodel over a systematic 100x100 m sample grid on both 1989 and 2008 aerial photographs. The degree of damage of 4 individual trees was assessed at every grid point in the surveying strips covering the surveyed area. Damage indicators were calculated and thematic maps were constructed on the basis of the interpretation of data for all the grid points. Results: For the research area a damage index (IO) of 68.36% for oak was determined by photointerpreting individual trees (2008) ; in other words, this percentage of pedunculate oak trees in the surveyed area was found to be in the damage degree of 2.1 and more. Of 68.36% trees classified in the damage degree of 2.1 or more, mean damage (SO1) amounted to 52.16% and could be classified in the damage degree of 2.2. In 1989, the mean damage index (IO) for pedunculate oak was 48.00%, and pedunculate oak trees with mean damage degree of 2.1 or more (SO1) amounted to 36.03%. The comparison of photointerpretation results from 1989 and 2008 shows that the damage index (IO) for pedunculate oak increased by more than 20%, whereas mean damage (SO) rose by almost 15%. An increase of more than 15% in mean damage of considerably damaged pedunculate oak trees can also be observed. Conclusions: The obtained results provide not only the current forest condition but also indicate the condition in the field and the purposefulness of aerial surveying, since aerial photographs allow an insight into the condition in the field in a short time period. This in turn enables the efficient application of measures to mitigate the consequences of dieback.

Impact of tree decline on spatial patterns of seedling-mycorrhiza interactions: Implications for regeneration dynamics in Mediterranean forests

In the last decades, an increasing number of forest decline events and widespread tree mortality have been reported worldwide as a consequence of different global change drivers. Such a general decrease in tree health and cover has a large potential to impact mycorrhizal communities, but this issue remains largely unexplored.We used a Bayesian framework to analyze the impact of Quercus suber decline on spatial patterns of seedling-mycorrhiza interactions in mixed Mediterranean forests in Southern Spain, and evaluate the relative importance of this symbiosis as a driver of oak seedling establishment.Our models showed that the spatial variability found in the patterns of oak seedling colonization by both arbuscular mycorrhizas and ectomycorrhizas was partially linked to the process of Q. suber decline. Moreover, seedling survival and growth was influenced by the intensity of mycorrhizal colonization, but in quite unexpected ways. Arbuscular mycorrhizas had a larger effect on seedling performance than ectomycorrhizas, and the effects of both groups were negative or neutral but never positive.We conclude that because the spatial distribution of the seedling-mycorrhiza association responded to the identity and health status of individual trees, and mycorrhizal infection did in turn affect seedling performance, tree decline might affect forest dynamics through changes in plant–soil biota feedbacks.

Belowground infections of the invasive Phytophthora plurivora pathogen enhance the suitability of red oak leaves to the generalist herbivore Lymantria dispar

1. Globally, vast areas of forest are currently threatened by Lymantria dispar L. and Phytophthora species, which cause widespread declines and cascading ecological impacts. One important aim of evolutionary and ecological studies is to understand their interactions.2. The present study tests whether Quercus rubra L. trees naturally infected with P. plurivora T. Jung & T.I. Burgess or free of infection are more suitable for L. dispar herbivory, and if relationships between L. dispar performance and herbivory may vary depending on whether trees are infected or free of infection.3. In choice tests, the consumed area of leaves from trees infected by P. plurivora was four times larger than that from non‐infected trees, probably because the increased values of N, soluble protein, and water content observed in the leaves of infected trees enhanced acceptability. Although larval performance was better in Phytophthora‐infected trees, relationships between larval performance and defoliation did not significantly interact with the health status of trees.4. The present results suggest that the impact of P. plurivora on natural and managed ecosystems may generate a positive feedback loop for oak decline. The link between the behavioural and physiological responses of L. dispar to infected trees and the population growth in nature deserves further investigation.

Peranan Sistem Repong Damar Terhadap Pendapatan, Asupan Makan Dan Status Gizi Balita : Studi Kasus Di Desa Pahmungan Kecamatan Pesisir Tengah Kabupaten Pesisir Barat

ABSTRACT Regions Special Purpose or KDTI (Ministry of Forestry decree No.47/Kpts-II/1998) Repong Damar indigenous forest area of 29,000 ha which is a best practice community-based forest management in the western part of Lampung Province yet known about its capacity to ensure the sustainability of human resource development primarily critical starting at the age of five or its called toddlers. This study was doing from March to April 2014 in the village of Pahmungan District of the West Pesisir. The purpose of this research is: Knowing the linkage between population and income damar tree tenure, household food expenditure, protein intake toddlers, health status and nutritional status of toddlers. Data acquisition was done through interviews to collect data ownership damar tree population, income, food expenditure, health status and food intake (food recall) as the basis for determining the toddler nutritional status of children is calculated by the method of anthropometry (Ministry of Health, 2010). Parameter optimization using the software Minitab 16. The conclusions has proven there is a real link between the role of damar agroforest system to income, health status, and nutritional status of toddlers. Found relations or real relationship between income of damar agroforest [YI] with a population of damar tree with a model [YI]i= -0.1770 +0.023150[PHN]i. Furthermore simultaneously discovered the real relationship between food expenditure (YII) with [YII] as illustrated by the model [YII]i= 1.1546 +0438 [YI]. Further simultaneously discovered the real relationship between protein intake toddlers [YIII] with food expenditure [YII] with the model [YIII]i= 17 012 +3703 [YII]. Keyword: Repong damar, income, health status and nutritional status of toddlers

Seasonal variations of ectomycorrhizal communities in declining Quercus ilex forests: interactions with topography, tree health status and Phytophthora cinnamomi infections

SeasonalvariationsinectomycorrhizalsymbiosisofQuercusilextreeswerestudied,withspecialemphasisontree health status, Phytophthora cinnamomi root infections and topography. Five Q. ilex forests in western Spain were selected,andca.40 000roottipsfrom3decliningand3non-decliningtreesperforestwereexamined.Ectomycorrhizal fungal abundance and P. cinnamomi root infections were quantified seasonally for 2 years, and an assessment was made of the water soil content and physiological status of trees during summer, the most stressful season. Seasonal changes in ectomycorrhizal fungal abundance were higher for Tomentella spp. than those for Russula spp. and Cenococcum geophilum, but these changes were not influenced by topography, tree decline status and P. cinnamomi root infections. Seasonal variations of non-vital tips were conditioned significantly by the decline status of trees. A higher proportion of non-vital tips and a lower proportion of vital non-mycorrhizal tips were observed in declining than in non-declining trees. Abundance of C. geophilum and Tomentella spp. was not influenced byP. cinnamomi root infections but by topography. Abundance of Russula spp. was not influenced byP.cinnamomirootinfectionsbutbythedeclinestatusoftrees.Therelationshipsfoundbetweentreephysiology and ectomycorrhizalabundance changed significantly depending on the decline status of trees. For thefirsttime, seasonal variations in ectomycorrhizae inP. cinnamomi-infectedQ. ilexforests are reported. The lowdiversityand abundance of ectomycorrhizal fungi associated with declining trees should be further studied in order to uncover causes or consequences of Q. ilex crown transparency.

Site-Specific Plant Condition Monitoring Through Hyperspectral Alternating Least Squares Unmixing

Alternating least squares (ALS) is a blind source separation method commonly used in chemometrics to simultaneously estimate the absorption spectrum and concentration of different components in a chemical sample. In this study, the transferability of ALS from chemometrics to agricultural remote sensing is evaluated. Due to the subpixel contribution of background components, spectral unmixing has become an indispensable processing step in the spectral analysis of agricultural areas. Yet, traditional unmixing techniques only allow estimating the subpixel cover distribution of different components, but fail to provide an estimate of pure spectral signature of the crop component. This info is, however, highly valuable, as this pure crop signature could be used to monitor the health status of trees. Here, we anticipate that ALS can provide a solution. ALS estimates both the concentration and the absorption spectra of different components in a chemical sample and this can easily be translated into estimating both the subpixel cover fraction and spectral signature of different components in a mixed image pixel. We tested the performance of ALS on binary synthetic mixtures of citrus canopy and soil spectra, as well as on a ray-tracing experiment of a virtual orchard. ALS indeed allowed to simultaneously estimate the subpixel cover distribution (RMSE=0.05), as well as the pure spectral signatures of different endmembers (RRMSE<;0.12), and considerably improved the extraction of biophysical parameters (Δ R <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> up to 0.43). Thus, ALS provides a promising new image analysis tool for agricultural remote sensing.

Occurrence of Phytophthora plurivora and other Phytophthora species in oak forests of southern Poland and their association with site conditions and the health status of trees.

Phytophthora plurivora and other Phytophthora species are known to be serious pathogens of forest trees. Little is known, however, about the presence of P. plurivora in Polish oak forests and their role in oak decline. The aims of this study were to identify P. plurivora in healthy and declining Quercus robur stands in southern Poland and to demonstrate the relationship between different site factors and the occurrence of P. plurivora. In addition, the virulence of P. plurivora and other Phytophthora species was evaluated through inoculations using 2-year-old oak seedlings. Rhizosphere soil was investigated from 39 oak stands representing different healthy tree statuses. The morphology and DNA sequences of the internal transcribed spacer regions (ITS) of the ribosomal DNA and the mitochondrial cox1 gene were used for identifications. P. plurivora, an oak fine root pathogen, was isolated from rhizosphere soil samples in 6 out of 39 stands. Additionally, Phytophthora cambivora, Phytophthora polonica and Phytophthora rosacearum-like were also obtained from several stands. The results showed a significant association between the presence of P. plurivora and the health status of oak trees. Similar relationships were also observed for all identified Phytophthora species. In addition, there was evidence for a connection between the presence of all identified Phytophthora species and some site conditions. Phytophthora spp. occurred more frequently in declining stands and in silt loam and sandy loam soils with pH ≥ 3.66. P. plurivora and P. cambivora were the only species capable of killing whole plants, producing extensive necrosis on seedling stems.

Ectomycorrhizal symbiosis in declining and non-declining Quercus ilex trees infected with or free of Phytophthora cinnamomi

Quercus ilex decline and the presence of the soil-borne pathogen Phytophthora cinnamomi are hypothesised to be associated with shifts in ectomycorrhizal fungi abundance. Soil properties may also influence the relation of this pathogen to ectomycorrhizae. To investigate these associations, 96 Q. ilex declining stands were selected in western Spain and both declining and non-declining trees were sampled. Soil properties (soil depth, Ah horizon thickness, texture, pH, redox potential, soil bulk density and N–NH4+ and N–NO3− concentrations), P. cinnamomi root infections and ectomycorrhizal fungi abundance were assessed. The most dominant ectomycorrhizal morphotypes were Cenococcum geophilum, Tomentella spp. and Russula spp. Lower percentages of non-vital and vital ectomycorrhizal root tips were observed in declining than in non-declining trees. No significant differences in parameters characterising the ectomycorrhizal community between trees infected with or free of P. cinnamomi were observed. However, results indicate that non-mycorrhizal root tips are vulnerable entry points for the pathogen into the tree. More tips were colonised by Russula spp. and other ectomycorrhizal fungi in non-declining infected trees than in declining infected trees. Trees growing on stream banks showed a lower abundance of ectomycorrhizal root tips in fine-textured soils than in coarse-textured soils. Ectomycorrhizal tip abundance was positively related to Ah horizon thickness, irrespective of tree health status. The presence of P. cinnamomi altered relations between ectomycorrhizal abundance and several soil properties. The limited ectomycorrhizal diversity in Q. ilex declining stands and interactions of ectomycorrhizal abundance with soil texture, topography and P. cinnamomi root infections are reported and discussed.

Study on the mobility and bioavailability of PTEs in soils from Urban Forest Parks in Sofia, Bulgaria

Forest parks in many urbanized areas are affected by the anthropogenic pollution as demonstrated by the poor health status of many trees. The concentrations of harmful agents like Potentially Toxic Elements (PTEs) can be very high in urban soils and their availability is an important issue for biological components in these environments. This study focuses on the mobile forms of PTEs extracted by 1М NH4OAc at pH=7 in relation to determining their bioavailability for forest trees in oak ecosystems in urban areas. The area studied is along an urban–rural gradient from the Sofia region, Bulgaria. The NH4OAc extracts mainly “biologically active” fraction of elements in soils comprising primarily the soluble and exchangeable forms and in some cases showed good positive correlation with PTE accumulation in trees. Four experimental forest park sites (U1, U2, U3 and U4) created on Hortic/Technic Anthrosols were selected along the urban gradient in the Sofia region. The control sites located in rural zones with natural soils Cambisols and Luvisols (R1, R2, R3 and R4) were used as reference. Strong correlations were found between mobile forms of Cu, Zn, Pb, Cd in urban soils and a number of soil parameters (pH, CEC and texture). The mobility is related to soil pH and with more acidic soils a higher mobility is shown, which is statistically significant for Pb. The element Cu is less mobile in the soil and is localized in the top layer, where it is mainly associated with soil organic matter. The mobile (NH4OAc extractable) portions of Cu, Zn, Pb, and Cd (mg/kg soils) in Urban Soils ranged between: 0.74 and 2.61; 2.94 and 3.29; 1.34 and 3.28; and 0.02 and 0.16, respectively and those in Natural Soils ranged between: 0.73 and 1.65; 1.20 and 5.29; 1.10 and 6.80; and 0.02 and 0.07. The significance of the mobile proportion was greatest for Cd in urban soils where it reached 33.3% of the total content. Despite the determined correlation between mobile forms of Pb and Cd with their total content in leaves of oak trees there is no clear visible effect on the tree health characteristics using parameters as defoliation and decoloration of crowns.

Tree ring width and health status of the red oak (Quercus rubra L.) under urban conditions in Szczecin (NW Poland)

Tree ring width and health status of the red oak (Quercus rubra L.) under urban conditions in Szczecin (NW Poland)

Managing and Monitoring Tree Health and Soil Water Status During Extreme Drought in Melbourne, Victoria

Drought can lead to mortality in urban tree populations. The City of Melbourne, Victoria, Australia, manages a large population of trees that provide important ecosystem services and cultural heritage values. Between 1997 and 2009 Melbourne was affected by a serious drought resulting in significant tree health decline. Elms and planes in particular, were badly affected. This paper presents data from a survey of tree health status, and of studies of retrofitted buried drip line irrigation. A study of soil wetting in autumn of 2009 found that the use of drip irrigation had, in most cases, little or no effect on soil moisture levels and a modeled study of tree water use showed that water delivered by drip irrigation provided only a fraction of the water required by a mature tree. By contrast, drip irrigation in late winter was able to recharge soil moisture levels. Mechanisms responsible for the decline in tree health seen during the drought are discussed. While the drought has temporarily been alleviated, climate change scenarios for southern Australia suggest that increased rainfall variability and drought events will be more common. The experiences gained during the recent drought event provide useful information for urban tree managers planning for the future.