Tree Maintenance Research Articles

MPLS망을 이용한 인터넷 멀티캐스트 라우팅 프로토콜 모델

본 논문은 MPLS(Multiprotocol Label Swtiching) 망에서 인터넷 멀티캐스트 라우팅 프로토콜을 지원하기 위한 방안을 제시한다. 인터넷 멀티캐스트 라우팅 프로토콜은 트리의 구성방식과 속성에 따라 최단거리트리 방식, 공유트리 방식 및 복합트리 방식 등으로 분류된다. 각 방식에 따라 MPLS 망에서 지원해야 하는 기능이 달라진다. 특히, 단/양방향성 트리 링크, Flooding/Prune 방식의 트리 구성, 하나의 멀티캐스트 그룹에 다중 트리의 존재 등 여러 가지 미해결이거나 해결하기 어려운 문제점들이 존재한다. 본 논문에서는 몇가지 가정을 세우고, 이를 바탕으로 각 멀티캐스트 라우팅 프로토콜을 MPLS 망에서 지원하기 위한 방안을 제시한다. Flooding/Prune 방식의 멀티캐스트 라우팅 프로토콜에 대해서는 새로이 브로드캐스팅용의 레이블을 정의하여 해결하고, 공유트리 방식에 대해서는 기 제안된 블록기반 멀티캐스트 전송기법을 도입하여 셀 인터리빙(Call Interleaving) 문제를 해결하며, 마지막으로 복합트리 방식에 대해서는 기존 멀티캐스트 라우팅 프로토콜에 수정된 SPT 전환 기능을 추가하므로써 MPLS 지원문제를 해결한다. 제안하는 방법이 기존의 방법보다 비교해 보았을 때 전송지연에서 우수한 성능을 보임을 모의 실험을 통해서 확인하였다. This paper describes the new method for Internet multicast routing protocols using MPLS (Multiprotocol Label Switching) networks. Internet multicast routing protocols are divided into three categories in terms if tree types and tree characteristics : a shortest path tree a shared tree and hybrid tree types. MPLS should support various multicast mechanisms because of extremely different IP multicast architectures, such as uni-/bi-directional link, Flooding/prune tree maintenance mechanism. the existence of different tree types with the same group, etc. There are so many problems over MPLS multicast that the solutions can't be easily figured out. In this Paper, we make a few assumptions on which the solutions of IP multicast routing protocols over MPLS networks are given. A broadcasting label is defined for the shortest path tree types. Cell interleaving problems of the shared tree types is solved by using block-based transmission mechanism. Finally, the existing hybrid-type multicast routing protocol is reasonably modified Shortest Path tree type to support MPLS multicast. It has been shown that these modifications give better performance (transmission delay) than the orignal method.

GROWTH SITUATION OF RUNNING THROUGH TREES IN COMPOUND CHANNEL OF KOKAI RIVER

The maintenance of trees in the compound channels is now paid to attention. In this paper, the result of a study on growth situation of running through trees was described in the case of Kokai river the tributary of Tone river. The investigation items are height of trees, diameter of trees, height under the branch, width of the tree crown and etc. Especially, investigation for growth process of running through trees is focused on the relation between age of trees, riverbed and growth speed of tree, etc. Result obtain in this paper is as follows that the ancient trees of Kokai river were violated by the trees invaded newly.

A case for tree migration and integrated tree maintenance in QoS multicasting

The proliferation of QoS-aware group applications coupled with the limited availability of network resources demand for efficient mechanisms to support QoS multicasting. During a life-cycle of a multicast session, three important events can occur: membership dynamics, network dynamics, and traffic dynamics. The first two are concerned with maintaining a good quality (cost) multicast tree taking into account dynamic join/leave of members, and changes in network topology due to link/node failures/additions, respectively. The third aspect is concerned with flow, congestion, and error control. There has been many solutions proposed for dealing with each of these issues. However, the issue of tree migration has not been addressed as part of these solutions. In this paper, we highlight the importance of tree migration as a mechanism for handling membership and network dynamics in core-based multicasting, prove that it is NP-Complete, and propose four heuristic algorithms for it. The proposed algorithms are evaluated under two performance metrics: service disruption and resource wastage. Our simulation studies show that two of the algorithms offer comparable performance to that of the other two, in addition to being highly scalable and easily implementable. Moreover, we also propose an integrated approach for group management involving both local and global tree maintenance techniques.

A Discrete Event Simulation of a Municipal Street Tree Maintenance Operation

By using commercially available simulation software, a computer model for a typical municipal street tree maintenance operation is presented. Variables, such as the incoming work orders, crew assignments and productivity standards that represent the workflow of a service-on-demand street tree maintenance program, were included. Although additional simulated complexities are involved, the developed model provides a foundation from which managerial decision making and a typical tree care operation may be analyzed.

Optimal partition of QoS requirements on unicast paths and multicast trees

We investigate the problem of optimal resource allocation for end-to-end QoS requirements on unicast paths and multicast trees. Specifically, we consider a framework in which resource allocation is based on local QoS requirements at each network link, and associated with each link is a cost function that increases with the severity of the QoS requirement. Accordingly, the problem that we address is how to partition an end-to-end QoS requirement into local requirements, such that the overall cost is minimized. We establish efficient (polynomial) solutions for both unicast and multicast connections. These results provide the required foundations for the corresponding QoS routing schemes, which identify either paths or trees that lead to minimal overall cost. In addition, we show that our framework provides better tools for coping with other fundamental multicast problems, such as dynamic tree maintenance.

Scalable multicast protocol in IP-based mobile networks

In this paper, we present an alternative design, RBMoM (Range-Based Mobile Multicast), for efficiently supporting multicast for mobile hosts on the Internet. The current version of Mobile IP proposes two approaches to support mobile multicast, which are remote subscription and bi-directional tunneling. The former provides the shortest routes for delivery of multicast datagrams to mobile hosts; the latter hides host mobility from all other members of the group (therefore, no any overhead in the multicast tree maintenance). RBMoM intends to trade off between the shortest delivery path and the frequency of the multicast tree reconfiguration by controlling the service range of the multicast home agent (MHA). Actually, we will find that remote subscription and bi-directional tunneling are the extremes of RBMoM. From the point of view of the MHA and the service range concepts, RBMoM is a generalization of both approaches and a unifying mobile multicast approach. The simulation results show that RBMoM can adapt to the fluctuation of both host movement and the number of mobile group members, and outperforms the current two Mobile IP multicast solutions.

A Summary and Forecast of Demand for Municipal Street Tree Service on Staten Island, New York

The objective of this study was to establish a reasonably accurate demand forecasting model for municipal street tree services on Staten Island, New York. Using the raw data gathered from years from 1996 through 2000, a chart and mathematical equation for anticipated monthly demand were derived for the year 2001. The development of the model was accomplished with simple arithmetic computations and computer-assisted regression analysis. Although occasional storm damage skewed some monthly figures, it is apparent that demand for public tree maintenance on Staten Island is decidedly seasonal and predictable.

Pirone's Tree Maintenance. 7th ed

Pirone's Tree Maintenance. 7th ed

The Complexity of Constructing Evolutionary Trees Using Experiments

<p>We present tight upper and lower bounds for the problem of constructing evolutionary trees in the experiment model. We describe an algorithm which constructs an evolutionary tree of n species in time O(n d logd n) using at most n |d/2| (log2|d/2|−1 n + O(1)) experiments for d > 2, and<br />at most n(log n + O(1)) experiments for d = 2, where d is the degree of the tree. This improves the previous best upper bound by a factor Theta(log d). For d = 2 the previously best algorithm with running time O(n log n) had a bound of 4n log n on the number of experiments. By an explicit adversary argument, we show an <br />Omega(nd logd n) lower bound, matching our upper bounds and improving the previous best lower bound<br />by a factor Theta(logd n). Central to our algorithm is the construction and maintenance of separator trees of small height. We present how to maintain separator trees with height log n + O(1) under the insertion of new nodes in amortized time O(log n). Part of our dynamic algorithm is an algorithm for computing a centroid tree in optimal time O(n).</p><p>Keywords: Evolutionary trees, Experiment model, Separator trees, Centroid tree, Lower bounds</p>

Colonization of Agricultural Windbreaks by Forest Trees: Effects of Connectivity and Remnant Trees

Planted agricultural windbreaks may provide habitat for forest tree species and facilitate forest regeneration within the agricultural landscape, if the windbreaks are colonized by forest trees. In order to examine the potential for windbreaks to foster forest regeneration, I surveyed the understories of 51 windbreaks in Monteverde, Costa Rica, for forest tree seedlings. The windbreaks had been planted 5–6 yr earlier. Ninety-one forest tree species (including both primary and secondary forest species) were found in the windbreaks; however, many of the species occurred in low densities. The mean density of forest tree seedlings in the windbreaks was 2.14 seedlings/m2. Landscape factors appeared to have important effects on tree recruitment patterns. Windbreaks that were connected to forest had significantly higher densities of forest tree seedlings and greater numbers of forest tree species in their understories than windbreaks that were not connected to forest. In particular, connected windbreaks had higher densities and more species of bird-dispersed trees than nonconnected windbreaks. These differences probably reflect the greater activity of frugivorous birds within connected windbreaks and the resulting higher input of forest tree seeds. Windbreaks with remnant forest trees had significantly higher densities of forest tree seedlings of other species and more forest tree species than windbreaks lacking remnant trees. By serving as habitats for forest tree species, windbreaks may contribute to the maintenance of forest trees within agricultural landscapes and serve as tools for forest restoration in the tropics.

Pirone's tree maintenance

The Seventh Edition, now named in honour of Dr. P. P. Pirone, who authored the first five editions and co-authored the sixth, has been revised to reflect the enormous amount of new information available since the last edition, including the latest techniques in selecting, planting, and protecting trees. The authors explain how to evaluate the site (the soil, drainage, and exposure), how to select the right tree for that location, and how to prune, fertilize, and spray for pests. There is an extensive section on the diagnosis and control of tree pests and diseases, and on problems such as construction damage, gas injury, sunscald, leaf scorch, and air pollution. While the general structure of the sixth edition has been retained, there are several topics-notably hazardous trees and coping with tree pests and diseases-that have received greater attention than in previous versions of the book. The second half of the book comprises a systematic listing of the major landscape trees found in North America, describing the specific pests and diseases that attack each species. Well organized, clearly written, and beautifully illustrated with many new photographs, Pirone's Tree Maintenance is an encyclopedic resource, the first place to turn for information on dogwoods and elms, magnolias and redwoods, or any other tree growing in North America. Anyone serious about gardening will want this book on their shelf.

ISSR Scientists Develop New Clove Varieties

ABSTRACT Dwarf and large genes for clove plants have been located within clove germplasm selections collected by the Indian Institute for Spices Research. The dwarf gene should enable the development of clove production systems that will accommodate more trees per unit land area and facilitate tree maintenance and harvest.

Tree Wardens and Utility Arborists: A Management Team Working for Street Trees in Massachusetts

Public trees along streets and roads are often jointly managed by municipalities and electric companies. This research obtained information about community forestry programs and assessed the level of cooperation between the two management entities. The study queried electric utility staff arborists and municipal tree wardens, the arboricultural professionals in Massachusetts who are directly responsible for the planting, maintenance, and removal of street trees in urban and community forests. Results showed that the majority of communities still lack street tree inventories and management plans. Major advances in utility arboriculture have resulted in the need for trained and qualified arboricultural professionals to implement the new practices and techniques. Municipal arboriculture professionals give high ratings to the cooperation between communities and electric utilities when the private companies employ trained arborists on staff.

自然林のある斜面住宅地についての居住者の評価 : 住宅地における「残した緑」についての居住者の評価 その2

The study aims at clarifying residents evaluation of living environment with natural-forests and natural geographical features in detached housing area through questionnaire survey to residents and field investigation survey. The following results are take into consideration. 1. The residents who live with natural environment give a higher evaluation against their living environment in particular natural landscape, co-living with animals, and sense of seasons. 2. Those residents tend not to feel less burden to maintain their garden. 3. However, inadequate maintenance of their garden anticipates negative impacts to neighbors. 4. The residents who have their garden at slope give a higher evaluation on good vista, sunshine and ventilation, on the other hand give negative evaluation on useful of garden. 5. Accordingly it would be of importance to formulate a better management role and method of garden, rise of social awareness on necessary of maintenance of trees for maximizing residents' satisfaction on their environment.

Factors Influencing Water Split of Pecan Fruit

Water stage fruit split (WS) is an erratic and complex problem often causing major crop losses to susceptible pecan [Carya illinoinensis (Wangenh.) K. Koch] cultivars. This study identified two episodes of WS for `Wichita' pecan—a highly susceptible cultivar. The previously recognized precipitation-induced fruit splitting is the major episode; however, a previously unrecognized precipitation-independent, minor episode can also occured before the major episode. This minor episode was associated with the low solar irradiance and high relative humidity—conditions commonly associated with August rains. The crop characteristics of affected trees also influenced WS in that WS increased as crop load per tree increased. Fruits were also more likely to exhibit WS if located within the lower tree canopy. Treatment of foliage with an antitranspirant immediately before split-inducing conditions increased WS. Maintenance of moist soils for ≈2 weeks before WS-inducing conditions substantially reduced WS-related crop losses. These findings help to explain the erratic nature of WS and indicate that maintenance of trees in a well-watered state for ≈2 weeks before the initiation of shell hardening may substantially reduce WS-related crop losses in certain years.

Tree Growth Regulator Effect on Phototropism - Its Implication for Utility Forestry

Pruning procedures such as V-trimming or side-trimming used by electric utilities in tree maintenance programs result in asymmetrical light exposure within tree canopies, producing the potential for phototropic growth response. The tree growth regulators (TGRs) paclobutrazol and flurprimidol are used to reduce the rate of shoot regrowth following pruning. The mode of action involves complexing of the growth retardant with cytochrome P -dependent enzymes in the metabolic pathway for gibberellins, plant hormones responsible for shoot elongation. Because cytochrome P450 also is a part of the blue light receptor system that controls phototropism, it was hypothesized that shoot growth, as well as phototropic curvature, would be reduced by paclobutrazol and flurprimidol. Effects of soil-applied (0, 0.5, 1, and 5 ppm) paclobutrazol and flurprimidol on shoot growth and phototropism of greenhouse-grown seedlings were found to vary among species. Neither shoot growth nor phototropic curvature in American sycamore (Platanus occidentalis L.) was reduced by treatment with the TGRs. In contrast, shoot growth of silver maple (Acer saccharinum L.) was reduced by all concentrations of both paclobutrazol and flurprimidol, whereas phototropic curvature was reduced only by flurprimidol. Phototropic curvature of etiolated zinnia {Zinnia elegans 'Scarlet'Jacq.) was reduced by both growth regulators.

Modelling changes in dimensions, health status, and arboricultural implications for urban trees

Canberra, the capital of Australia since 1911, has been developed into a modern city from its original site on a nearly treeless plain. Today the city has about 300,000 inhabitants and 500,000 trees. The authors were requested by the managers of the urban public tree resource to survey their asset and to develop a computer-based system that would aid them in anticipating future maintenance requirements and its costs. This paper reports on our response. We have surveyed 3,000 streets and parks in the city, noting the species, number, and condition of every public space tree. We have also obtained the dimensions of sample trees, noting their total height, maximum crown width, height of maximum crown width, diameter at maximum crown width, and height at crown break. A management system has been developed using Microsoft AccessTM. Using standard regression techniques available on the package JMPTM, we found that total tree height was related to age for all species and that all other parameters of interest were related to height or transformed values of height. We assumed a sigmoidal growth curve and calibrated 114 height/age curves to cover the 165,000 trees of the 340 species we have in our database. As well we used the data on tree condition to determine the rate at which populations change from healthy to stressed. By interviewing foremen and supervisors we were able to determine the maintenance treatments carried out in Canberra, the equipment used, and the number of trees that can be treated in a day, for each type of operation. The management system can be used to display the current inventory for each street or park, by suburb, in the database. It can also be used to model future increases in size or crown condition, to predict the operations that will be required as a consequence of tree growth or crown deterioration, and finally, by applying multipliers to equipment and personnel, to estimate the future costs of tree maintenance. Managers can use the system to anticipate problems such as uneven expenditure requirements in future years.

Passive nighttime warming facility for forest ecosystem research.

A nighttime warming experiment is proposed. Over the last four decades a significant rise in nighttime minimum temperature has been determined from analysis of meteorological records from a global distribution of locations. The experiment involves nighttime deployment of infrared (IR) reflecting curtains around four sides of a forest canopy and across the top of the forest to mimic the top-down warming effect of cloud cover. The curtains are deployed with cable and pulley systems mounted on a tower and scaffolding structure built around the selected forest site. The trunk space is not enclosed except as an optional manipulation. The curtains reflect long-wave radiation emitted from the forest and ground back into the forest warming the trees, litter, and soil. Excellent infrared reflection can be obtained with commercially available fabrics that have aluminum foil bonded to one side. A canopy warming of 3 to 5 degrees C is expected on cloudless nights, and on cloudy nights, a warming of 1 to 3 degrees C is anticipated relative to a control plot. The curtains are withdrawn by computer control during the day and also at night during periods with precipitation or excessive wind. Examples of hypothesized ecosystem responses to nighttime warming include: (1) increase in tree maintenance respiration (decreasing carbon reserves and ultimately tree growth), (2) increase in the length of the growing season (increasing growth), (3) increase in soil respiration, (4) increase in litter decomposition, (5) increase in mineralization of N and other nutrients from soil organic matter, (6) increase in nutrient uptake (increasing growth), and (7) increase in N immobilization in litter. Hypothesis 1 has the opposite consequence for tree growth to Hypotheses 2 and 6, and thus opposite consequences for the feedback regulation that vegetation has on net greenhouse gas releases to the atmosphere. If Hypothesis 1 is dominant, warming could lead to more warming from the additional CO(2) emissions. Site-specific meteorological, ecophysiological, and phenological measurements are obtained in the warming treatment and in a carefully selected control plot to investigate site-specific hypotheses. Measurements made on both plots for a baseline period and during the period of curtain deployment provide data to test the hypotheses statistically by the "before-after-control-impact" method applicable to unreplicated experiments. The enclosure has a modular design that can be adapted and combined with other forest-scale manipulation experiments such as free air CO(2) enrichment and throughfall displacement.

Atmospheric Carbon Dioxide Reduction by Sacramento's Urban Forest

Sacramento County's 6 million trees store 8 million tons of CO2 (31 t/ha), and annually sequester 238,000 t (0.92 t/ha). Air-conditioning (157 GWh) and space-heating (145 TJ) savings from the urban forest further reduce emissions by 75,600 t of CO2 annually (0.29 t/ha). These avoided emissions are only 32% of the amount sequestered, due to a clean, hydroelectric energy supply. Annual CO,, release associated with tree maintenance is estimated at 9,400 t (0.04 t/ha), or 3% of the amount sequestered and avoided. In net, the urban forest removes approximately 304,000 t (1.2 t/ha) each year, with an implied value of US$3.3 million ($0.55/tree). Carbon dioxide reduction by Sacramento's urban forest offsets the total amount of COa emitted as a byproduct of human consumption by 1.8%. Most benefits accrue on residential lands in the city and suburban sectors, where rates of storage and sequestration are about one-half those reported for U.S. forests. Guidelines for managing urban forests to reduce atmospheric CO2 are presented.

Residential Tree Planting and Care: A Study of Attitudes and Behavior in Sacramento, California

Site surveys were conducted on residential properties in Sacramento, California, and residents were given questionnaires about whether they had added trees to their properties, their motivations for planting trees, and the extent and frequency of their maintenance of the trees on their properties. These surveys indicate that most residents (68% of the sample) plant trees on their properties; that residential areas are relatively densely planted (with room for about 9% more trees than are already in place); that issues of comfort (shade) and appearance play more of a role in the decision to plant trees than do concerns about energy savings, environmental benefit, or privacy; that tree planting tends to be greatest early in a resident's tenure in a home; and that convenience is a strong predictor of the types of tree maintenance provided by residents relative to that provided by contractors.