Landscape Tree Species Research Articles

남부지방 조경수종의 탄소저감과 계량모델†: - 동백나무, 배롱나무 및 가시나무를 대상으로 -

This study quantified, through a direct harvesting method, storage and annual uptake of carbon from open-grown trees for three landscape tree species frequently planted in the southern region of Korea, and developed quantitative models to easily estimate the carbon reduction by tree growth for each species. The tree species for the study included <italic>Camellia japonica, Lagerstroemia indica</italic>, and <italic>Quercus myrsinaefolia</italic>, for which no information on carbon storage and uptake was available. Ten tree individuals for each species (a total of 30 individuals) were sampled considering various stem diameter sizes at given intervals. The study measured biomass for each part of the sample trees to quantify the total carbon storage per tree. Annual carbon uptake per tree was computed by analyzing the radial growth rates of the stem samples at breast height or ground level. Quantitative models were developed using stem diameter as an independent variable to easily calculate storage and annual uptake of carbon per tree for study species. All the quantitative models showed high fitness with <italic>r</italic>² values of 0.94-0.98. The storage and annual uptake of carbon from a <italic>Q. myrsinaefolia</italic> tree with dbh of 10 cm were 24.0 kg and 4.5 kg/yr, respectively. A <italic>C. japonica</italic> tree and <italic>L. indica</italic> tree with dg of 10 cm stored 11.2 kg and 8.1 kg of carbon and annually sequestered 2.6 kg and 1.2 kg, respectively. The above-mentioned carbon storage equaled the amount of carbon emitted from the gasoline consumption of about 42 L for <italic>Q. myrsinaefolia</italic>, 20 L for <italic>C. japonica</italic>, and 14 L for <italic>L. indica</italic>. A tree with the diameter size of 10 cm annually offset carbon emissions from gasoline use of approximately 8 L for <italic>Q. myrsinaefolia</italic>, 5 L for <italic>C. japonica</italic>, and 2 L for <italic>L. indica</italic>. The study pioneers in quantifying biomass and carbon reduction for the landscape tree species in the southern region despite difficulties in direct cutting and root digging of the planted trees.

Comparison of water-use characteristics of landscape tree (Tabebuia argentea) and palm (Ptychosperma macarthurii) species in a tropical roof garden with implications for urban water management

In cities, landscape palms and trees are planted for scenic views and normally maintained with frequent irrigation. With similar water input, their morphological difference may lead to different water-use that varies seasonally. Thus, evaluating their water-use patterns is necessary to achieve proper urban water management. Here, we examined water-use characteristics of Tabebuia argentea and Ptychosperma macarthurii, a tree and a palm species, in a roof garden in Bangkok, Thailand. Self-constructed Granier’s probes were used for sap flux measurement and monitored for five months in 2016. Results showed that palm transpired 3–4 times higher water than tree daily. With frequent watering, tree was more sensitive to increasing vapor pressure deficit (D) than palm on rain-free days. When rainfall occurred, however, both species became less sensitive to D and continued consuming more water at high D. Extending the analysis to include a hypothetical warming climate with +4.8 °C temperature, we found that tree saved more water than palm on rain-free days. However, daily transpiration of both species increased similarly by 14–18% on rainy days. These results imply that Tabebuia argentea may provide ecosystem benefits by conservatively using water under drought and decelerating runoff from the garden when storms come. In contrast, Ptychosperma macarthurii may provide ecosystem disservice with high water-use in dry season but may slow down runoff in wet season and therefore benefiting downstream ecosystems. These findings are useful for selective planting associated with future changes in precipitation patterns, leading to sustainable urban water management.

Gas exchange and growth of landscape tree species in response to drought and post establishment applied organic mulch

Landscape industry employees often advises homeowners to place organic mulches on soils surrounding trees in new and existing landscapes. However, limited research has been conducted to determine if organic mulch placed below established landscape trees enhances tree growth. Under non-irrigated conditions, our research objective was to compare gas exchange and growth of established landscape trees that either had, or did not have organic mulch placed on the soil surface surrounding each tree. English oak (Quercus robur), Chinquapin oak (Q. muehlenbergii), and Shantung maple (Acer truncatum) trees were planted 2002. In Fall 2008, six trees of each species were randomly assigned a mulch treatment: organic mulch or no organic mulch placed on the soil below the tree canopy. From Fall of 2008 through Fall of 2011 trees received weekly irrigation. Beginning 2012, trees were not irrigated. Daily weather data were collected by an onsite weather station. Throughout the 2012, 2013, and 2014 growing seasons bud break data was collected from each tree. In addition, throughout each growing season mid-day gas exchange data (stomatal conductance, photosynthetic rate, etc.) were collected. At the end of each growing season, growth data were assessed. Data indicate soil under mulch was cooler, had greater soil moisture, and less extreme temperature fluctuations extremes when compared to soil without mulch. Throughout the experiment, species and treatment differences were found in gas exchange data. Shoot growth tended to be greater for non-mulch trees. However, leaf area varied between species and mulch treatments. Results suggest benefits (greater gas exchange, growth, etc.) of organic mulch placed under non-irrigated established trees is species specific, and should be carefully considered prior to making recommendations.

Two Novel Fungal Symbionts Fusarium kuroshium sp. nov. and Graphium kuroshium sp. nov. of Kuroshio Shot Hole Borer (Euwallacea sp. nr. fornicatus) Cause Fusarium Dieback on Woody Host Species in California.

Shot hole borer (SHB)-Fusarium dieback (FD) is a new pest-disease complex affecting numerous tree species in California and is vectored by two distinct, but related ambrosia beetles (Euwallacea sp. nr. fornicatus) called polyphagous shot hole borer (PSHB) and Kuroshio shot hole borer (KSHB). These pest-disease complexes cause branch dieback and tree mortality on numerous wildland and landscape tree species, as well as agricultural tree species, primarily avocado. The recent discovery of KSHB in California initiated an investigation of fungal symbionts associated with the KSHB vector. Ten isolates of Fusarium sp. and Graphium sp., respectively, were recovered from the mycangia of adult KSHB females captured in three different locations within San Diego County and compared with the known symbiotic fungi of PSHB. Multigene phylogenetic analyses of the internal transcribed spacer region (ITS), translation elongation factor-1 alpha (TEF1-α), and RNA polymerase II subunit (RPB1, RPB2) regions as well as morphological comparisons revealed that two novel fungal associates Fusarium kuroshium sp. nov. and Graphium kuroshium sp. nov. obtained from KSHB were related to, but distinct from the fungal symbionts F. euwallaceae and G. euwallaceae associated with PSHB in California. Pathogenicity tests on healthy, young avocado plants revealed F. kuroshium and G. kuroshium to be pathogenic. Lesion lengths from inoculation of F. kuroshium were found to be significantly shorter compared with those caused by F. euwallaceae, while no difference in symptom severity was detected between Graphium spp. associated with KSHB and PSHB. These findings highlight the pest disease complexes of KSHB-FD and PSHB-FD as distinct, but collective threats adversely impacting woody hosts throughout California.

Photosynthetic responses to soil water stress in summer in two Japanese urban landscape tree species (Ginkgo biloba and Prunus yedoensis): effects of pruning mulch and irrigation management

Stomatal regulation involves beneficial effects of pruning mulch and irrigation on leaf photosynthesis in Prunus yedoensis and Ginkgo biloba under moderate drought. G. biloba showed conservative water use under drought. Leaf photosynthesis is highly sensitive to soil water stress via stomatal and/or biochemical responses, which markedly suppress the growth of landscape trees. Effective irrigation management to maintain leaf photosynthesis and information on species-specific photosynthetic responses to soil water stress are essential for the sustainable management of landscape trees in Japan, in which summer drought often occurs. In order to investigate effective irrigation management, we used plants with moderate soil water stress as controls, and examined the effects of daily irrigation and pruning mulch on leaf photosynthesis in container-grown Ginkgo biloba and Prunus yedoensis, which are the first and second main tall roadside trees in Japan. Stomatal conductance was significantly increased by pruning mulch and daily irrigation, with similar increases in leaf photosynthesis being observed in P. yedoensis and G. biloba. In order to obtain information on species-specific photosynthetic responses to soil water stress, we compared the responses of leaf photosynthesis and leaf water status to reductions in soil water content (SWC) between the two species. G. biloba maintained a constant leaf water potential, leaf water content, maximum carboxylation rate, and electron transport rate with reductions in SWC, whereas reductions were observed in P. yedoensis. We concluded that pruning mulch and irrigation effectively offset the negative impact of moderate water stress on leaf photosynthesis in summer in P. yedoensis and G. biloba via stomatal regulation, and also that G. biloba maintained its photosynthetic biochemistry and leaf water status better than P. yedoensis under severe water stress.

Specific Detection and Identification of American Mulberry-Infecting and Italian Olive-Associated Strains of Xylella fastidiosa by Polymerase Chain Reaction.

Xylella fastidiosa causes bacterial leaf scorch in many landscape trees including elm, oak, sycamore and mulberry, but methods for specific identification of a particular tree host species-limited strain or differentiation of tree-specific strains are lacking. It is also unknown whether a particular landscape tree-infecting X. fastidiosa strain is capable of infecting multiple landscape tree species in an urban environment. We developed two PCR primers specific for mulberry-infecting strains of X. fastidiosa based on the nucleotide sequence of a unique open reading frame identified only in mulberry-infecting strains among all the North and South American strains of X. fastidiosa sequenced to date. PCR using the primers allowed for detection and identification of mulberry-infecting X. fastidiosa strains in cultures and in samples collected from naturally infected mulberry trees. In addition, no mixed infections with or non-specific detections of the mulberry-infecting strains of X. fastidiosa were found in naturally X. fastidiosa-infected oak, elm and sycamore trees growing in the same region where naturally infected mulberry trees were grown. This genotype-specific PCR assay will be valuable for disease diagnosis, studies of strain-specific infections in insects and plant hosts, and management of diseases caused by X. fastidiosa. Unexpectedly but interestingly, the unique open reading frame conserved in the mulberry-infecting strains in the U. S. was also identified in the recently sequenced olive-associated strain CoDiRO isolated in Italy. When the primer set was tested against naturally infected olive plant samples collected in Italy, it allowed for detection of olive-associated strains of X. fastidiosa in Italy. This PCR assay, therefore, will also be useful for detection and identification of the Italian group of X. fastidiosa strains to aid understanding of the occurrence, evolution and biology of this new group of X. fastidiosa strains.

Dikegulac Sodium and Benzyladenine Effects on Six Landscape Tree Species during Container Production

A study was conducted to evaluate dikegulac sodium (dikegulac) and benzyladenine (BA) as branching agents on landscape trees during production. Common among the six species in this two-year study was an increase in new shoot development following the application of dikegulac. Relative to shoot counts of nontreated plants, trees treated with a single foliar application of 800 to 3200 ppm of dikegulac had an increase in shoot numbers of 29 to 107% in Japanese maple, 75 to 158% in red maple, 67% in redbud, 50 to 65% in bald cypress, and 56 to 103% in black gum. Nontreated plants of green ash formed only one or two lateral shoots in 2011, whereas dikegulac-treated green ash had 10 to 12 new shoots. In 2012, green ash treated with 200 to 800 ppm of dikegulac developed 100 to 150% more new shoots than nontreated green ash. Foliage of all species, except Japanese maple, was injured to varying degrees by dikegulac, but the injury dissipated over the growing season. BA promoted increased shoot development only in bald cypress, and canopies of that species were visually fuller and more compact than those of bald cypress treated with dikegulac.

Analysis on Landscape Tree Species Composition in the Gardens of the West Lake Scenic Area, Hangzhou, China

Based on the investigation on tree species within plant communities of parks and gardens in Hangzhou West Lake Scenic Area, some indices such as species composition, importance value, application frequency, diameter class structure, health condition, and seasonal aspect structure of woody plants were calculated. The present situation and contributing factors of utilization of the tree species resources in the parks and gardens of the West Lake were analyzed, and some corresponding suggestions were proposed. The results were as follows: 1) There were 166 species of woody vascular plants in the parks and gardens of the West Lake, which belonged to 58 families and 108 genera. Compared with zonal plant species in Hangzhou and landscape plants in advanced foreign cities, the plant species number was very low. 2) About 30 species had high important value and application frequency. It indicated that the arbor and shrub species in each community in the parks and gardens of the West Lake was small at present. 3) The results of study of diameter class structure showed that, the average breast-height diameter of trees in the West Lake was 34cm, and about 67% trees had 20-40cm breast-height diameter. It indicated that a majority of trees were mature. 4) The results of study of health status showed that, most plant species developed well. 5) The results of study of seasonal aspect showed that, the plant landscape in the parks and gardens of the West Lake had different characteristics in different seasons, which were numerous flowers in spring, green shades in summer, colorful leaves in autumn and beautiful branches and trunks in winter.

Resistance to Dutch elm disease reduces presence of xylem endophytic fungi in Elms (Ulmus spp.).

Efforts to introduce pathogen resistance into landscape tree species by breeding may have unintended consequences for fungal diversity. To address this issue, we compared the frequency and diversity of endophytic fungi and defensive phenolic metabolites in elm (Ulmus spp.) trees with genotypes known to differ in resistance to Dutch elm disease. Our results indicate that resistant U. minor and U. pumila genotypes exhibit a lower frequency and diversity of fungal endophytes in the xylem than susceptible U. minor genotypes. However, resistant and susceptible genotypes showed a similar frequency and diversity of endophytes in the leaves and bark. The resistant and susceptible genotypes could be discriminated on the basis of the phenolic profile of the xylem, but not on basis of phenolics in the leaves or bark. As the Dutch elm disease pathogen develops within xylem tissues, the defensive chemistry of resistant elm genotypes thus appears to be one of the factors that may limit colonization by both the pathogen and endophytes. We discuss a potential trade-off between the benefits of breeding resistance into tree species, versus concomitant losses of fungal endophytes and the ecosystem services they provide.

Selection of Landscape Tree Species of Tolerant to Sulfur Dioxide Pollution in Subtropical China

Sulfur dioxide (SO2) is a major air pollutant, especially in developing countries. Many trees are seriously impaired by SO2, while other species can mitigate air pollution by absorbing this gas. Planting appropriate tree species near industrial complexes is critical for aesthetic value and pollution mitigation. In this study, six landscape tree species typical of a subtropical area were investigated for their tolerance of SO2: Cinnamomum camphora (L.) J. Presl., Ilex rotunda Thunb., Lysidice rhodostegia Hance, Ceiba insignis (Kunth) P. E. Gibbs & Semir, Cassia surattensis Burm. f., and Michelia chapensis Dandy. We measured net photosynthesis rate, stomatal conductance, leaf sulfur content, relative water content, relative proline content, and other parameters under 1.31 mg·m-3 SO2 fumigation for eight days. The results revealed that the six species differed in their biochemical characteristics under SO2 stress. Based on these data, the most appropriate species for planting in SO2 polluted areas was I. rotunda, because it grew normally under SO2 stress and could absorb SO2.

Biochar Amendment Increases Resistance to Stem Lesions Caused by Phytophthora spp. in Tree Seedlings

Soil amendment with biochar is thought to confer multiple benefits to plants including induction of systemic resistance to plant pathogens. Pathogens in the genus Phytophthora cause damaging diseases of woody species throughout the world. The objective of this study was to test 1) whether biochar amendment induces resistance to canker causing Phytophthora pathogens; and 2) how this resistance is related to the amount of biochar amendment in two common landscape tree species: Quercus rubra (L.) and Acer rubrum (L.). Seedlings of Q. rubra and A. rubrum were planted in peatmoss-based potting mix uniformly amended with 0%, 5%, 10%, or 20% biochar by volume. Plants in each treatment group were stem wound-inoculated with an isolate of Phytophthora cinnamomi Rands (host: Q. rubra) or P. cactorum (Leb. and Cohn) Schröeter (host: A. rubrum) using standard agar-plug inoculation procedures. Amendment of potting media with 5% biochar reduced horizontal expansion of lesions in both hosts, whereas the same treatment significantly reduced vertical expansion of lesions in A. rubrum (P &lt; 0.05). In addition, 5% biochar resulted in a higher midday stem water potential in Q. rubra (P = 0.066) and significantly greater stem biomass in A. rubrum compared with inoculated control plants (0% biochar, P &lt; 0.05). Our results suggest that biochar amendment has the potential to alleviate disease progression and physiological stress caused by Phytophthora canker pathogens and there is likely an optimal level of biochar incorporation into the root media beyond which the effects may be less pronounced.

Organic Amendment Effects on Soil Carbon and Microbial Biomass in the Root Zone of Three Landscape Tree Species

There is increasing interest in amending degraded soils with organic matter to improve soil quality, especially in urban areas where rehabilitation of damaged soils may enhance tree growth and provision of ecosystem services. To assess the potential of such organic amendments for producing a sustained alteration in soil biological characteristics, researchers studied the effects of three organic amendments incorporated into the root zone of three tree species on root development, soil carbon dynamics, and soil microbial biomass over one year beginning 20 months after amendment application. Soil amendment with leaf-based, and to a lesser extent, biosolids-based composts increased root length within the amended root zone of red maple (Acer rubrum), but not of pin oak (Quercus palustris) or chestnut oak (Q. montana). There was a concomitant increase in microbial biomass carbon for red maple. Across all species, sphagnum peat moss amendment reduced microbial biomass carbon by 47% compared to unamended root zones and suppressed maximum seasonal soil respiration relative to composts. In contrast, leaf-based compost increased microbial biomass carbon by 12% (P = 0.0989) compared to unamended root zones. Carbon/nitrogen ratios remained stable throughout most of the year except in the root zones of chestnut oak and pin oak amended with peat, where it declined 44%–85%. Total soil carbon was stable in all treatments, although unamended soils averaged about 40% lower than amended soils. Across all species and treatments, cumulative fine root length explained 19% of the variation in microbial biomass carbon. The study authors conclude that soil microbial activity can be increased by compost amendment of the root zone and that this increase is mediated to some degree by tree roots. In addition, stable C/N ratios suggest this alteration in the root zone may be sustainable. Further research may clarify whether compost amendment combined with tree planting can accelerate soil restoration.

Image measurements of leaf scorches on landscape trees subjected to extreme meteorological events

Trees grow in changing environments and are usually injured by many external factors including both abiotic and biotic. Leaf scorch is a main symptom for many landscape trees when they are stricken by meteorological extreme events, such as summer drought, strong typhoon and winter freezing and so on. In the study, the internal angle of injured area (IAIA) was defined in relation to vein lines and measured non-destructively for some landscape tree species. Meanwhile, the leaf scorch area percent (LSAP) and percent of scorched central vein (PSCV) were also determined from RGB images. Positive relationships between IAIA and LSAP and between PSCV and LSAP were found. The larger IAIA values for scorched leaves and smaller IAIA values for spot/anthracnose diseased leaves of the studied trees indicated that IAIA may be used as a diagnosing index of leaf scorch symptoms.

Reactive Oxygen Species and Alternative Respiration in the Developing Flowers of Two Subtropical Woody Plants

Petals, sepals, pistils, and stamens from flowers of two landscape tree species (Elaeocarpus hainanensis Oliv and Michelia alba DC) were analyzed to determine the changes in levels of reactive oxygen species (ROS), lipoxygenase (LOX) activity, and alternative pathway respiration throughout flower development. Histochemical and quantitative analyses revealed that ROS levels differed among tissues and stages of flower development. ROS levels were high in all flower tissues early in development and then declined to low levels late in development. ROS levels were highest in the stamen. In contrast, LOX activity, heat energy evolution, and the percentage of total respiration represented by alternative respiration in M. alba petals increased with flower development. The results suggest that ROS are involved in the growth of various flower tissues at early developmental stages and not only located on the tip site of growing tissues. The reduction in ROS generation later in development is probably due to the significant elevation in alternative respiration. The increase in LOX activity and heat energy evolution might contribute to the formation and release of some aromatic compounds and to flower opening. LOX, however, might not mediate ROS generation in the petal during development.

물배지의 종류 및 첨가물의 농도가 후피향나무 삽목묘의 발근 및 이식 후 활착에 미치는 영향

Cuttings based on water media are relatively low-cost and easy to manage compared to those based on soil media. Nevertheless, species that root out in water media are very few. Water-medium rooted cuttings are not widely used. In water media, the survival rate of cuttings is high, but in many cases, they only form callus while not rooting. If cuttings with callus formed in a water medium were to root and survive after being transplanted in soil, water-medium cuttings could be used as an important means of propagating landscape tree species. In this study, cuttings of Ternstroemia japonica having various reactions to water media were soaked in different types of water media. Their callus formation and rooting conditions were analyzed. The water-medium cutting swere then transplanted in soil, and conditions for their survival were examined. The study concluded: 1. Cuttings that only formed callus in water media were able to root and survive after being transplanted. 2. Cuttings with satisfactory callus formation showed more satisfactory survival conditions than those with unsatisfactory callus formation. 3. Cuttings rooted in water media showed a high survival rate of 96.6% after being transplanted. 4. Water-medium cutting of Ternstroemia japonica proved to be more effective in Late July or August than in late June. 5. Cuttings pre-treated in 50ppm-IBA for 24 hours showed better survival conditions than those that were not pre-treated inIBA. 6. Cuttings pre-treated in 50ppm-IBA for 24 hours and soaked in water media with 0.02% atonic, 0.02% polyoxin, and 0.01% polyoxin showed a rooting and survival rate of 80 to 85%. Regardless their low rooting rate, water-medium cuttings can show a high survival rate when these factors are considered: proper cutting time, plant hormone treatment, and types of water media. Accordingly, water-medium cuttings will emerge as major means of propagating landscape tree species that require small volumes of multi-species.

강원도 지역의 조경식물의 식재현황 분석

This study was carried out to improve planting and use of landscape plants in Gangwon-do. The designated plants by schools and cities in Gangwon-do were surveyed and then compared with the planted trees on streets, public parks, schools, etc. in 2009. There were 45 tree species and 43 flower species designated as school trees and school flowers at 632 schools in Gangwon-do. The majority of school tree species were Juniperus chinensis, Pinus densiflora, Abies holophylla, Ginkgo biloba, Pinus koraiensis, Taxus cuspidata, Zelkova serrata, and Pinus thunbergii. The ratio of native species to exotic was 35:10. The majority of school flower species Rosa centifolia, Forsythia koreana, Zinnia elegans, Rhododendron mucronulatum, Chrysanthemum morifolium, and Rosa rugosa. The ratio of native species to the exotic was 22:21. There were 12 flower species and 7 tree species designated as city trees and city flowers in 18 cities and guns. The high frequency flower species were Rhododendron schlippenbachii, Forsythia koreana, Magnolia sieboldii, and Prunus armeniaca var. ansu. The high frequency tree species were Ginkgo biloba, Pinus koraiensis, and Taxus cuspidata. There were 87 woody landscape tree species planted, and a total of 619,835 landscape plants were planted in Youngseo region (western part of Gangwon-do) in 2009. The ratio of native species to exotic species was 56:31. The majority of landscape trees planted were Pinus densiflora, Prunus yedoensis, Prunus sargentii, Comus officinalis, Pyrus pyrifolia, Rhododendron yedoense var. poukhanense, Pinus koraiensis, Taxus cuspidata, Hibiscus syriacus, Forsythia koreana, Zellkova serrata, Acer triflorum, Rhododendron obutusum, and Ligustrum obtusifolium A in 2009. The ratio of native species to the exotic was 64:36. There were 77 woody landscape tree species planted, and a total of 914,668 landscape plants were planted in Youngdong region (eastern part of Gangwon-do) in 2009. The ratio of native species to exotic was 52:25. The major landscape trees planted were Pinus thunbergii, Rhododendron lateritium, Rhododendron schlippenenbachii, Hibiscus syriacus, Prunus yedoensis, Pinus densiflora, Syringa dilatata, Rhododendron yedoense var. poukhanense, Rosa rugosa, Prunus sargentii, Rosa centifolia, Juniperus chinensis, Euonymus japonica, Forsythia koreana, Chionanthus retusus, Acer palmatum, and Chaenomeles sinensis. The results indicate that landscape plants need to be diverse in species in each region of Gangwon-do. Selection of suitable plants for each region and the use of native species need to be emphasized.

Responses of some landscape trees to the drought and high temperature events during 2006 and 2007 in Yamaguchi, Japan

Extreme weather events were analyzed based on the meteorological data from the year of 1967 to 2007 for Yamaguchi, Japan. The responses from landscape trees were also investigated mainly by the analysis of image pixel and spectral reflectance. Results show that after the dry, hot and windy summer in 2007, many landscape trees in Yamaguchi City tended to respond the extreme weather events by reducing their leaf surface area and receiving less radiation energy. Premature leaf discoloration or defoliation appeared on some landscape tree species and leaf necrosis occurred on tip and margin of many Kousa dogwood (Cornus kousa) trees at unfavorable sites. Described by image pixel analysis method, the leaf necrotic area percentage (LNAP) of sampled dogwood trees averaged 41.6% and the sampled Sasanqua camellia (Camelia sasanqua) tree also showed fewer flowers in flower season of 2007 than that in 2006. By differential analysis of partial discolored crown, it presented a logistic differential equation of crown color for sweet gum (Liquidambar styraciflua) trees. It suggested that the persistent higher temperature and lower precipitation could be injurious to the sensitive landscape trees at poor sites, even in relative humid area like Yamaguchi.

Effects of Waterlogging on Growth and Physiology of Hopea odorata Roxb

This study examines the growth and physiological characteristics of Hopea odorata growing under waterloggingcondition. H. odorata was selected as it is widely planted as urban landscape tree species which experienced some growthstresses. Two waterlogging treatments and a control were designed. Forty 5-year old saplings each were subjected towaterlogged condition for 30 days which were then allowed to recover for a further 30 days as Treatment 1 (T1) andwaterlogged condition for 60 days as Treatment 2 (T2). Aboveground and belowground biomass including leaf area wasdetermined before and at 30 and 60 days of study. The net photosynthesis (Anet), stomatal conductance (Gs), transpirationrate per unit leaf area (EL) and leaf to air vapour pressure deficit (????W) were assessed weekly for 60 days. The resultsshowed that there were no significant differences between treatments for all growth attributes. There were also nosignificant reductions of these attributes found within treatments throughout the experimental period. Furthermore, nosignificant effects were observed in gas exchange variables. The results demonstrate that severe waterlogged conditiondid not affect the physiology of H. odorata. These findings add to the increasing evidences that H. odorata is a flood aswell as a pollution tolerance species that ensuring it to survive and grow well in urban areas by regulating the partitioningstrategies.

Estimating Water Needs of Landscape Palms in Mediterranean Climates

The responses of five landscape palm species [king palm (Archontophoenix cunninghamiana), mediterranean fan palm (Chamaerops humilis), queen palm (Syagrus romanzoffiana), chinese windmill palm (Trachycarpus fortunei), and california fan palm (Washingtonia filifera)] to three levels of irrigation [50%, 25%, and 0% (no irrigation) of reference evapotranspiration] were evaluated in a coastal mediterranean climate in Irvine, CA. Cumulative leaf production varied greatly among the species, but only king and chinese windmill palms produced more leaves with additional irrigation. All species maintained at least minimally acceptable visual quality at the no-irrigation treatment. Mediterranean fan and california fan palms expressed near optimum performance with no irrigation. Many established landscape palms can maintain at least minimally acceptable appearance for an extended period with little or no supplemental water in coastal mediterranean climates. However, when rainfall plus irrigation is less than 50% of reference evapotranspiration, sensitive landscape palms could be expected to appear less attractive and grow less. Responses of palm species in this study were similar to those of many other landscape tree and shrub species, but the water needs of landscape palms are considerably less than those of commercial date palm (Phoenix dactylifera), oil palm (Elaeis guineensis), or coconut palm (Cocos nucifera).

Estimating Water Needs of Landscape Palms in Mediterranean Climates

The responses of five landscape palm species [king palm (Archontophoenix cunninghamiana), mediterranean fan palm (Chamaerops humilis), queen palm (Syagrus romanzoffiana), chinese windmill palm (Trachycarpus fortunei), and california fan palm (Washingtonia filifera)] to three levels of irrigation [50%, 25%, and 0% (no irrigation) of reference evapotranspiration] were evaluated in a coastal mediterranean climate in Irvine, CA. Cumulative leaf production varied greatly among the species, but only king and chinese windmill palms produced more leaves with additional irrigation. All species maintained at least minimally acceptable visual quality at the no-irrigation treatment. Mediterranean fan and california fan palms expressed near optimum performance with no irrigation. Many established landscape palms can maintain at least minimally acceptable appearance for an extended period with little or no supplemental water in coastal mediterranean climates. However, when rainfall plus irrigation is less than 50% of reference evapotranspiration, sensitive landscape palms could be expected to appear less attractive and grow less. Responses of palm species in this study were similar to those of many other landscape tree and shrub species, but the water needs of landscape palms are considerably less than those of commercial date palm (Phoenix dactylifera), oil palm (Elaeis guineensis), or coconut palm (Cocos nucifera).