ISDN is a vital topic for today’s CCNA and CCNP candidates, especially for the ICND and Intro exams – you’ve got to know ISDN inside and out to pass those exams. Naturally you want to include it in your home lab. What many candidates don’t realize is that you can’t connect two Cisco routers directly via their Basic Rate Interface (BRI) interfaces you’ve got to have another device between them called an ISDN simulator.
An ISDN simulator is not one of those software programs pretending to be routers (“router simulators”) this is a piece of hardware that acts as the telephone company in your home lab. Older simulators come with preprogrammed phone numbers and SPIDs, where newer ones let you program the phone numbers you want to use. Either way, an ISDN simulator is great for your CCNA/CCNP home lab, because you can practice dial scenarios that actually work. And you get to troubleshoot the ones that don’t, which is also important to learn! )
You don’t need any special cables or connectors you just connect both of your routers’ BRI interfaces to the ISDN simulator with a straight-through cable and you’re ready to go.
In years past, this was a major problem for 640-801, 811, and 821 studies, because the simulators used to be so expensive. New ones can still be pricey ($600 and up), but with the sudden influx of used ISDN simulators on ebay and Cisco resellers, you can get a used one that will do the job for you.
Why are there suddenly so many ISDN simulators on the market? Cisco recently removed ISDN from the CCIE R&S exam, so a lot of CCIE rack resellers as well as private individuals are selling their simulators. There’s never been a better time to add ISDN to your home lab. If taken care of (kept out of extreme heat), they can last for quite a few years. The one I purchased for my IE home lab is still working well.
If you choose to purchase a new simulator, you can run a Google search to find vendors. I’ve made two purchases from www.vconsole.com over the last few years and both of those simulators have worked beautifully.
As I said earlier, there’s never been a better time to add ISDN to your home lab. Don’t just settle for trying to memorize theory – get your hands on the real deal, practice and fix your configurations, and you’ll be amazed at what you learn and how well you do on your CCNA and CCNP exams!
Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage (www.thebryantadvantage.com), home of free CCNA and CCNP tutorials, The Ultimate CCNA Study Package, and Ultimate CCNP Study Packages. Video courses and training, binary and subnetting help, and corporate training are also available.
For a FREE copy of his latest e-books, “How To Pass The CCNA” or “How To Pass The CCNP”, send a request to chris@thebryantadvantage.com today !
A up to date survey announced that notably fewer than half of UK mature adults take out life insurance cover. At the end of the day making the wise decision to invest in comprehensive life insurance is usually one thing that regularly seems to end up at the very end of your to-do list. Even so, in due course arranging your comprehensive cover can endow your closest loved family with extra financial self-confidence. Hence when is the spot on instant to peer more carefully into life cover?
The simple riposte is the more readily the better. Choosing to purchase life cover is counted amidst one of the most sensible things one could do to preserve your partner and children’s fiscal future. It significantly helps a family monetarily in the occurrence of the fatality of an individual & means money can be made open for dear ones, sometimes even in the unfortunate event of a fatal incurable illness. However, fully comprehensive life cover isn’t just only about shielding your offspring’s monetary security, those who do not currently have a brood are able to choose to purchase comprehensive life insurance to make sure their partner is without question taken care of financially in the occasion of their loss of life. There can be may confusing options when selecting life cover so be sure to do your research thoroughly.
There are about four main life moments that frequently trigger one to acquire comprehensive life insurance cover. The 1st without debate securing a brand spanking new habitat.
Acquiring a brand spanking new house without debate a trying time, especially if it is your initial step on the real-estate ladder. The stress of having yours and or maybe even your spouses monetary future tied up in you home could be crushing. So this will probably be an ideal – & reassuring – time to buy fully comprehensive life cover, which will often be put to good use to pay off your families mortgage payments if something unforeseen occurs to you or your partner. It of course consequently means your treasured ones might not at present have to face up to the tragic additional disturbance of losing both your family member & the newly acquired family dwelling.
The 2nd trigger occurrence for obtaining life insurance is certainly formalising a relationship through marriage or a civil partnership. If you have a short time ago sworn your never-ending love to someone, it goes without saying that you’d wish to make absolutely sure they will be financially confident in the unfortunate incident that something occurs to you.
Every industry is affected by rules and regulations. Environmental issues are becoming of greater importance as more and more regulations go into affect. Cleaner air, water, pesticides even the garbage we throw away is regulated. Do you think much about it?
Even the oceans are cause for environmental regulation. The resent oil tanker that broke in two off the coast of Spain has become world news and threatens the ocean’s eco system and the industries that rely on it. From an investment perspective its the fishing industry’s concern, as losses can run into the multi-millions. But fishermen aren’t the only one’s who’ll suffer.
In 2015 all oil transport ships are to be double hulled. That’s the current regulations and they’re already talking about reforming that act. That spill is going to force those regulations to be changed, and rapidly. What that means is more ships will have to be built sooner. But it will also increase the cost of transporting oil in the short term and that means YOU are going to pay more for heating oil and gas for your car.
That brings me to the point of this article. The environment can provide green investments or mean investments, depending on which end of the spectrum your on.
The fishing industry off the coast of Spain is going to suffer, ship builders are going to benefit, the transportation industry is going to suffer and then the micro economic effects begin to (pardon my pun) spill over to smaller businesses.
Investing in environmental companies that are charged with clean up is a pretty safe bet. But only those that are consistently involved are the safest investment and have the greatest chance for growth; better green than mean. Go for safe, consistent segments.
What do we mean by a safe investment? In the environmental industry there are certain sectors where demand for their services are growing, especially since regulations began to be enacted to deal with the mounting waste issues. Two of the safest areas we’ve found are in the recycling field. Automotive byproducts, tires, are one of the more consistent demands in recycling. It’s a green investment! The other is toxic metals and water. Very consistent demand, another green investment!
Axcess Business News looked at two green investments in the recycling industry, Greenman Technologies, Inc. and KBF Pollution Management, Inc. We recently interviewed the CFO of Greenman Technologies, Inc. (AMEX: GRN) in Axcess Business News Inside Wall Street column and had selected it as one of our “best picks” in our Stock Guide. The other company, KBF Pollution Management, Inc. (OTCBB: KBFP) is also in our Small Cap Corner’s “best picks” column. GRN recycles tires and KBFP cleans up toxic metals and waste water. Two environmental companies in the recycling sector, both with consistent demand for their services. Green investments!
GRN and KBFP By The Numbers
Greenman Technologies, Inc.
Classification: business services. In the first row are the Industry Averages and in the second row are Greenman Technologies, Inc. numbers.
Source: Market Guide as of 11/17/02
Mkt. Cap P/E Profit (%) Margin Price to Sales ROE Sales per Share Debt to Equity EPS Growth
(5 yr.)
404.71 33.60 9.49% 6.73 15.48 NA 0.24 17.67
30.82 21.51 4.97% 1.09 93.04 1.84 2.35 NM
KBF Pollution Management , Inc.
Classification: waste management services. In the first row are the Industry Averages and in the second row are KBF Pollution Management, Inc. numbers.
Source: Market Guide as of 11/17/02
Mkt. Cap P/E Profit (%) Margin Price to Sales ROE Sales per Share Debt to Equity EPS Growth
(5 yr.)
408.31 77.94 2.78% 1.38 5.19 NA 1.76 25.93
10.17 NM -25.01% 1.79 -24.33 0.04 0.49 NM
Below is a 3-month chart of Greenman Technologies Inc (AMEX: GRN) compared to KBF Pollution management, Inc. (OTCBB: KBFP) and the Pollution Index (POL).
Looking for the Green
First of all, “classifications” can be confusing. GRN is classified as “business services”, yet their S&P Company Report classifies them as “capital goods: environmental services” and KBFP is classified as “waste management services”.
Trusting the numbers is another issue. Market Guide portrays the information to be current, yet based on their recent announcements of sales and earnings for the 3rd quarter ending Sept 30, neither GRN or KBFP’s is exact. Data often isn’t enough, you have to look deeper to find the green.
Clearly both companies are undervalued. Their industry classifications show very high P/E ratios. Makes you think your looking at Microsoft’s numbers about 10 years ago. GRN is outperforming its industry average and based on those averages, if it traded equal to its peer group the stock should be priced around $3.50 not $2.00 where it currently trades. KBFP on the other hand has an even higher P/E ratio for its industry classification; Market Guide’s figures appear to be wrong. KBFP announced on 11/14/02 that its sales had increased 50% for the quarter in comparison to the same period in the prior year and its earnings were reported to be $273,508 for the period ending compared to $109,700 for the previous year! So based on that recent announcement, KBFP is also undervalued. If it traded equal to its peer group the stock should be priced around $0.10 not $0.06 where it currently trades.
Let’s examine why Axcess Business News believes these are safe investments. The five year earnings per share growth estimates for GRN’s industry classification is 17.67%. Is your sagging portfolio of Telco stocks giving you that? I don’t think so! GRN has debt, yet they’ve been very aggressive in expanding through acquisition and only recently listed to the AMEX from the OTCBB in September. KBFP’s industry classification (5yr earnings per share growth estimates) is 25.93%. We like those kinds of numbers even better.
Both of these green investment companies have been aggressive and showing stellar improvements in their sales and earnings. They both have a lot of debt. But they both have a consistent market and most likely Market Guide’s 5-year industry averages are close to reality. Give those 5yr averages a 50% haircut and you’ve still got a good return. Better than the DJIA, certainly better than money markets or certificates of deposit and there’s room for appreciation as both companies are trading about 50% lower than their industry average.
Axcess Business News thinks that KBFP may be on the same path as GRN. They too are postured for growth and if they begin to go after acquisitions and list up to AMEX (remember, GRN was on the OTCBB) it could easily catch up to its peer group. GRN on the other hand has a head start and based on its prior growth investors may see more acquisitions happening.
Axcess Business News will continue to report on the activities of these companies for our readers as it’s sure to interest investors. Members should watch for an Axcess News Alert in their in-box! If your not a member, consider subscribing now and you can get these great market alerts too!
To view more wall street stories by Freddie Mooche, go to http://wwwtheaxcess.net and subscribe. Its free!
About the Author
Ms. Mooche is the senior financial columnist for Axcess Business News. She was Senior Analyst with Axiom Capital Corportion prior to becoming a Wall Street columnist and financial journalist. Her columns include, Inside Wall Street and Axcessing The Analysts.
© 2003 Vadim Smolyanov and Valentina Smolyanova
Translated from Russian. We shall be glad to receive your remarks on stylistics, grammar, and content.
Chapter I. Evolution of lifeless matter
We more likely fortunately than unfortunately are in the world where there is a time-space and a matter where a duality, variety and constant changes exist. But how to manage to describe World or its any phenomenon if you being in it?
The most interesting phenomenon known to a science is the Great explosion, a birth of the universe which was about 15-20 billion years ago. What had become the reason of it? The condition of the universe before the birth cannot be transferred by words means. It is follows of the known ancient texts concerning creation and essence of our world (the Bible, Vedic and Dao). This condition is described as containing All and Nothing simultaneously. Ancient texts force us to disconnect thinking logic and to trust in supersensual perception. But a problem, we have no supersensual perception. So we shall try to create model of development of a matter with the help of the empirical data, existing theories and logic, but we shall take position of ancient doctrines as the entry condition: “All in Nothing, Nothing in All”. Is lawful to conclude on it basis that the explosion reason was occurrence of the Unity (point). Occurrence of the Unity created the occurrence of the Variety potential (infinity). Unity and Variety as the total difference has made explosion. The aspiration from Unity to Variety has automatically given birth to opposite aspiration from Variety to Unity. These two aspirations have created a matter, space-time, all processes and the phenomena around of us and inside us. Difference of Unity and Variety, a point and infinity has given birth to space-time. Internal aspiration of superelementary particles to Unity and an external pulse to Variety have forced its to space overcoming and to participating in irreversible processes of uniting and disconnecting , that has given birth to time-line (an one-orientation from the past to the future) and a matter. After the era of Great explosion which last very short time interval was finished an era of Great association was begun with duration no more than t=10 in degree -35s. During this period there was a first phase transition of a matter (phase transition is a change of a condition of a matter, for example, transformation of water into steam). Superelementary particles and superelementary antiparticles have appeared in this era. Here there was a global copying of Unity and Variety on internal elements of system as difference between of superelementary particles and superelementary antiparticles and occurrence of gravitation. There were first interactions and first particles focused on interactions (gluons). The following period is marked by the next phase transition of matter. It is the period of androns formation (protons, neutrons, electrons, etc.). Nuclear forces are the basic interaction at this stage which were allocated from gravitation and have found a duality, ability to draw or push away. There were first microsystems where interactions between a few quarks form large variety of elementary particles. It is a first level of complexity known to a science. The aspiration to association at the bottom level is appeared in variety at the top level. All evolution of a matter proceeded by this principle.
Chapter II. Evolution of alive matter
The following significant period of evolution (about 3-4 billion years ago) was occurrence of alive matter which incorporates variety of a lifeless matter. At the first sight, an organism and mentality of animals continued to evolve by means of lifeless matter principles from simple to complex with inherent in all alive aspiration to reproduction and self-preservation. Taxis (knacks of spatial orientation aside favorable or from adverse conditions of environment, for example, turn of plants according to daily movement of the sun or change of elementary organisms movement depending on a chemical compound of environment) of monocelled developed in conditional and unconditioned reflexes (response of an organism to irritation) of multicellular, reflexes of the elementary were transformed to complex instincts (the genetic incorporated programme of actions is started at concrete external conditions) of insects. And, at last, at the supreme animals we notice abilities to training and the decision of simple tasks, for example use of boxes by the monkey for bananas gotten. The basic direction of mentality evolution and of organism evolution is considered increase of ability to fast adaptation at fast environment changes. Because of it is considered mammals are more advanced than, for example, insects. I’d like to not agree with this thesis. In a counterbalance of mammal ability to training and abilities of separate bodies to change of the functions without genetic changes at insects is an opportunity under adverse conditions to be long time in an embryon or to be exposed to a genetic mutation due to fast alternation of generations. We can mark from it that all animals and all flora is perfect essences and evolution completeness organisms. We can observe completeness in monocelled colonies, in behaviour of plenty bees or supreme animals. The biosphere of our planet during evolution has gotten a homeostasis (the medical term designating balanced harmony of an organism). We shall designate two principles of biosphere homeostasis. The first principle is a principle of “narrow specialisation”. Almost all kinds of an animal and flora specialise on rather narrow segment of food or inhabitancy, for example, being divided on herbivores and carnivorous. With the help of it steadily-renewable ecological circuits are built. The second principle is “return proportionality between adaptability and ability to breeding”. This principle does not allow to breed, for example, to large predators and to destroy all of herbivores. There is one more principle – “the god does not give horns for the butting cow”. The nature does not give superadvantage in bodies (powerful canines, claws or horns) and abilities (speed of movement, etc.). That can break a homeostasis (this principle can be related to the first because additional abilities expand “specialisation”). The evolution shaped these principles during billions years. So biosphere as against a lifeless matter includes the variety and forms unity through a homeostasis. The alive matter shows integrity at the top level uniting variety of the bottom level of system. Or otherwise the aspiration to variety at the bottom level is appeared in unity at the top level.
E-mail: vsmolyanov@yahoo.com
URL: www.chelovek-center.ru
About the Author
It is the part of article. The article contains the concept of person development on the basis of traditional religions and modern achievements in the world of science.
The world of laptop computers changes each and every day, thus making it tough to stay on top of all the most recent developments even for the tech savvy shopper. Laptop computers mainly have replaced desktop machines as the chosen option for home personal computer purchase. While Apple notebook computers are tremendously fashionable in the press & do not have virus problems, typically other Windows-installed notebook computers provide a very economical option, provided that a trustworthy virus protection security programme has been loaded onto the machine.
The most key factor to determine before looking for notebook computers is its usage. Understanding how a notebook computer is intended to be used helps you to identify what extra programmes will be required. This is important in understanding how specified the laptop computer must be. Someone who is planning on only surfing the Web and doing a small bit of word processing they will not need as quick a laptop as someone recording music or playing the latest three dimensional video games.
There are two things that control the power of a laptop computer more than all others; and they are the processor and the overall quantity of Random Access Memory. A faster CPU allows the laptop notebook to fulfil functions much more faster, while additional RAM also permits for more rapid performance because the CPU can utilise the RAM to momentarily boost the overall amount of computer memory accessible for it is own internal tasks. If like most people that sounds a little bewildering, just simply keep in mind: that the more RAM the computer has, the quicker it will perform.
The internal storage drive is where all software programs and files, for example pictures & music are kept. Without doubt, the larger size of the internal storage drive the more that can be backed-up on it. Almost all laptop computers come with DVD-R drives already integrated. BluRay drives may well also be available as a more expensive selection.
Once you have an idea for the required power of the laptop computer, the next big decision you have to make involves picking a brand. Apple notebooks are tremendously popular, well-made, and easy to operate, however they often tend to cost more or less twice as much as a comparably specified Microsoft notebook computer.
Sony notebook computers are very trendy machines to think about if you are performing a extensive amount of multimedia tasks. Most of their products come with FireWire slots which allow for simple connectivity to a range of digital video devices, such as video cameras or digital video recorders. Find a vast selection of technology products such as; laptops, 42 LCD TVs and digital photo frames from leading brands online.
Toshiba notebook computers are well-known for their performance & fittingness for running company programmes. They are reliable, sturdy computers.
Acer laptops give by far the most cost-effective solution around. They are pretty inexpensive, but still provide enough dependability & power to be deemed a worthwhile acquisition.
With the chance of overnight visitors, a great number of people will undoubtedly worry about the current sad state of their visitor bed. Time and time again a neglected room, the guest bedroom can be seen as an area to store objects that are no longer needed by the tenants, like that of a worn down dining table. Refusing your friends a night of un-interrupted sleep by providing them a sub-standard sleeping space is kindly not mentioned often, yet can produce some hard feelings. It’s important that you avoid this from occurring by pleasing your family & friends by giving them a first-rate place to put their tired heads. Even if your room allows for a separate visitor bed or a folding bed that can be put away when not in demand, having a proper location exclusively for visitors is a brilliant and respectful gesture that will certainly not go unnoticed.
A sofa bed can be a very good choice for family when living in a small flat. Sofa beds by design are capable of folding away into the sofa when not in use, and for that reason can be a highly practical piece of furniture to posses. This convertible piece can drastically increase the usage of a room, not only a guest room, but also the space can be used as a reading room when no one is staying over. Wise shoppers will unquestionably see the added value of a multi-use item of household furniture, both as a practical daily use sofa as well as an infrequent guest bed. Always try to plan for family and friends when decorating your space as this makes for a welcoming home. An added idea for people that do not have a spare room to devote to family is the fold out bed. The ‘hide-a-bed’ or cot as it may commonly be called is a piece designed to be got out when demanded and stowed away when not in demand. Fold out beds and sofa beds may also be good in homes with guest rooms to supply more guest sleeping quarters in the instance that your apartment becomes a fashionable vacation spot amongst friends and family.
Showing your worry for your guests health by picking a fine guest bed for their use without doubt lets them know you care. A proper night’s sleep can be remarkably hard to accomplish when in a different situation, however with a pleasurable sofa bed it can be a great deal easier. By carefully considering your choices, getting the ideal bed for your home will be thanked countless times over by your thankful houseguests. Whether your flat permits a sofa bed, a folded bed, or even a full guest room with a conventional style bed, the correct way in which you take care of your guests will be remembered for a considerable long time to come. Find a range of home products including; guest beds, single mattress and single beds from leading brands online.
The textbook definition of “administrative distance” is simple enough: “the measurement of a protocol’s believability”. It’s not enough to know the definition, however you’ve got to know when AD comes into the picture and when it does not.
When a packet needs to be routed, the router looks in its routing table for the next-hop IP address the packet should take to get to the destination. There may be more than one matching path, in which case the router will look for the “longest match”. The route that has the longest match – the route with the most bits in the mask set to “1″ – will be the route that is used.
Consider the following three routes from a fictional Cisco router:
I 172.17.0.0 /24 via 172.1.1.1
O 172.17.0.0 /25 via 173.1.1.1
R 172.17.0.0 /26 via 174.1.1.1
This router has three possible next-hop IP addresses that it can send packets destined for the network 172.17.0.0. The masks are of different lengths, meaning that the route with the longest match (again, the route with the most bits set to “1″) will be used. In this example, the RIP route will be used, since it has the longest match with a mask of /26. The administrative distances do not matter.
AD does matter when the masks are the same length, as shown here:
I 172.17.0.0 /24 via 172.1.1.1
O 172.17.0.0 /24 via 173.1.1.1
R 172.17.0.0 /24 via 174.1.1.1
The longest match rule always precedes the use of AD, but here there is a three-way tie regarding the masks. They’re all /24 (or 255.255.255.0 in dotted decimal). AD will be used to break this tie.
As mentioned, AD is a measurement of a protocol’s believability. It is important to keep in mind that the lowest AD will be preferred. And while the routing table will show you the ADs of the respective protocols, it’s a very good idea to know these ADs before taking the CCNA or CCNP:
Connected route: 0
Static Route: 1
EIGRP Summary: 5
External BGP: 20
EIGRP (Internal): 90
IGRP: 100
OSPF: 110
ISIS : 115
RIP: 120
EIGRP (External) : 170
Unknown: 255 (A router will not believe a source with an AD of 255, and such routes will not be placed into the routing table.)
The three protocols we looked at in the comparison were RIP, IGRP, and OSPF. While your first instinct may be that the OSPF route would be the most believable, IGRP actually has a lower AD than the other two and would be the route installed in the routing table.
Since IGRP does not support variable-length subnet masking and OSPF does, you may never see this scenario outside of an exam question. But if you do see it in the exam room or in a production network, you’ll understand how an IGRP route could be preferred over an OSPF route.
Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage (www.thebryantadvantage.com), home of free CCNA and CCNP tutorials, The Ultimate CCNA Study Package, and Ultimate CCNP Study Packages. Video courses and training, binary and subnetting help, and corporate training are also available.
For a FREE copy of his latest e-books, “How To Pass The CCNA” or “How To Pass The CCNP”, send a request to chris@thebryantadvantage.com today !
Allergies, Asthma and City Trees
Thomas Leo Ogren
Some urban tree species cause an inordinate amount of asthma and allergy problems, while other tree species cause little or no health problems. A large part of the problem is that the arborists and landscape professionals, who plant these trees, often don’t know the difference.
The type of trees (and shrubs) used in modern city landscapes has changed dramatically in the past three decades. In the past, the majority of street trees used were perfect-flowered, insect-pollinated trees, such as the once so common American elm tree.
Today though, many of the most widely used city trees are wind-pollinated species. Most of these species are unisexually flowered (dioecious and/or monoecious) and further compounding the problem, thousands of popular cultivars sold today are touted to be “seedless,” “low-maintenance,” “pod-free” or “litter-free.”
These fruitless, seedless trees are male plants, all male, and male trees produce prodigious amounts of allergenic pollen. Female trees produce NO pollen what so ever.
In dioecious-flowered trees such as most ash, willow and poplars, it is easy to propagate male only trees because they are separate-sexed. Monoecious trees, which in Nature always have both sexes (male and female flowers) on the same tree, also usually produce abundant pollen. It is possible to have all-male trees from the monoecious species. On many species the sexes will be born on separate branches, such as on a Honey Locust tree. If you take cuttings, or budwood, only from the branches with male flowers, then, you’ll get an all-male tree. Lots of monoecious Acer spp. cultivars are male-only plants. In a somewhat different way, there are also numerous monoecious species where only the top or only the bottom will have either male or female flowers. For example, the bottom half of a mature Italian Cypress for example is all-male. Female
wood is found only at the top of the plant. Thus, scion wood taken from the bottom usually produces “seedless” plants.
The terms “dioecious,” and “monoecious,” are botanical terms, not horticultural terms. We could perhaps say that a manipulated, asexually propagated all-male cultivar, taken from a monoecious species, is now “dioecious,” but this is not quite correct. A proper dioecious tree is one that in Nature is separate-sexed. These modern engineered trees are never found in Nature.
Interestingly, the first reference in print I ever found to this single sexing-out with monoecious street trees, was in a USDA booklet, from 1982, called “Genetic Improvement of Urban Street Trees.”
How Bad Is Allergy Now?
In 1959 the official rate of allergy in the U.S. was between 2 to 5% of the public. By 1999 the official rate of allergy had increased to an incredible 38% of Americans. Asthma, which was once considered rare, is now the number one chronic childhood disease in the US.
Where are Allergies and Asthma the Worst?
The most common allergen of all is pollen and since there are so many more plants growing in the country than in the city, it would make sense then that there is more allergy and asthma in the countryside. Right? No, wrong! Allergies and asthma are far worse in the city than they are in the country.
Several things contribute to this:
1.Pavement makes a poor pollen trap. Pollen in the city often lands on pavement where wind can cause it to become airborne again. In naturally vegetated areas where there is much more vegetation, pollen often lands on and becomes stuck in grasses, shrubs and vines or in trees.
2.Cities have more air pollution, which weakens the immune system and lung function.
3.Stress, which is generally higher in cities, can contribute to both asthma and allergy development.
4.Increased carbon dioxide levels within cities causes pollen-forming plants to produce more pollen with each bloom cycle, and also often causes urban plants to bloom more often.
5.Pollen loads are actually far greater in cities because there is a sexual imbalance within the plant community. In the city there is a preponderance of male trees and shrubs, while in the rural areas there is almost always a complete balance of plant sexuality. The excess of male plants in the city results in an excess of pollen.
6.The very lack of female plant materials in the urban environment also is a prime factor in the epidemic of allergy and asthma. Female flowers carry an electrical negative (-) charge (the trees are grounded with their roots) and airborne pollen holds a positive (+) charge. The tree and the pollen are mutually attractive; thus a female plant becomes a very effective pollen trap for pollen of its own species. But with almost no female trees and shrubs in modern landscapes, most of the pollen remains airborne.
How to Improve Health and Air Quality through Tree Selection
Landscaping to reduce allergies, especially pollen allergies, is an idea that is coming into its own. In the past few years several books have been written on the subject and interest is growing rapidly.
With the addition of OPALS, (Ogren Plant-Allergy Scale) arborists now have a means to design allergy-free plantings. This scale ranks all landscape plant materials on a simple 1 to 10 allergy basis. Trees that produce zero pollen, e.g., female cultivars, usually rank the best – number one. Trees that have abundant, highly allergenic pollen, especially those with very long bloom periods, are usually ranked the worst – in the 9-10 range. There are many trees and shrubs, however, that fall somewhere in between. Using a list of over 100 factors, OPALS numerically ranks each species and then further ranks the individual cultivars. There are often dramatic allergy differences even between two species in the same genus.
How Are Plants Allergy-Ranked?
OPALS was developed based on the following considerations: “What do plants that are well known to cause allergies have in common?” and “What do plants that are well known NOT to cause allergies have in common?” With these two questions it was possible to build two opposing sets of medical-botanical-allergy criteria. One set is positive and one set is negative. Examples of negative criteria: tiny flowers, excerted stamens, small (less than 25 microns in diameter) sized pollen grains, extended bloom period. Examples of positive criteria: complete flowered, sticky, heavy pollen grains, presence of nectaries, brief bloom period.
There are now over a hundred criteria used to develop OPALS rankings. Individual landscapers, city arborists, the USDA and the American Lung Association have already use the scale to make better landscaping decisions.
Based on the plant-allergy scale it is now possible to state, for example, that Acer rubrum – ‘Red Sunset’ maple, is ranked number one and causes no allergies. By comparison, ‘Autumn Spire,’ a male cultivar of red maple does cause allergies and is ranked number nine. Most Pine trees will rank at numbers 4 to 5 and will cause some allergy. Platanus species (sycamore) rank number eight, and cause quite a bit of allergy. A male Canary Island Palm, Phoenix canariensis, which is considered one of the worst at a ranking of 10, will produce an abundance of pollen that will cause severe allergic reactions to many living nearby.
Pollen dispersal rates have been measured since 1972 (Gilbert Raynor, NY meteorologist) and although many pollen grains travel far in the air, research shows that most often 99% of a tree’s pollen falls out and sticks within fifty feet of the tree. This means that the closer one is to the pollinating tree the greater the exposure. Thus, the job for arborists is to plant trees that will not expose everyone near them to allergenic pollen.
So, How Do You Tell the Boys from the Girls?
It isn’t always that obvious by looking at a tree (especially a young tree) as to whether or not it is a pollen-free female or a pollen-producing male. But since so many city trees are now asexually produced cultivars, the sex is predetermined. In the book Allergy-Free Gardening, which is the result of 15 years of research on this subject, several thousand trees were individually sexed and allergy-ranked. In some cities, pollen control ordinances are already on the books, although most of these could be improved an updated. Albuquerque, New Mexico is particular interesting, since it has attempted to curb allergies by prohibiting the sale and planting of any male cultivars.
As the public grows more knowledgeable about allergy-free landscapes, municipal arborists and landscape specialists will want to be ahead of the curve. They will want to show their clients that they are well-informed on the subject. In the future, instead of planting high allergy-trees, they will need to plan and plant ‘healthy’ urban landscapes.
References:
1.Lewis, Walter H., Airborne and Allergenic Pollen of North America, John Hopkins University Press, Baltimore, Maryland, 1976.
2.Jacobson, Arthur Lee, North American Landscape Trees, Ten Speed Press, Berkeley, California, 1996.
3.Koch, Christopher Von, Allergy, Die Woche, pg. 27, July 7, 2000, Hamburg, Germany.
4.Dworschak, Manfred, Der Spiegel, Feind am StraBenrad, Pp. 174, 175, Nr. 29, 2000.
5.Ogren, Thomas Leo, Turn Back the Pollen Clock, New Scientist, London, Pp. 46, 47, June 3rd, 2000.
About the Author
Thomas Ogren is the author of Allergy-Free Gardening, Ten Speed Press. Tom does consulting work on plants and allergies for the USDA, county asthma coalitions, and the Canadian and American Lung Associations. He has appeared on HGTV and The Discovery Channel. His book, Safe Sex in the Garden, was published in 2003. In 2004 Time Warner Books published his latest book: What the Experts May NOT Tell You About: Growing the Perfect Lawn. His website: www.allergyfree-gardening.com
