Space invaders

The next-door neighbors have a thriving Norway maple that has grown ever more immense and is now blocking your views, shading your flower gardens, and sending out far-questing roots that suck up your lawn irrigation. Your worst fear is that the behemoth is going to fall on your house during some hurricane. You've asked the neighbors to take it down, explaining that rather than a thing of beauty it is the worst, most invasive weed tree in the Northern Hemisphere. They don't get it. ''It's a living thing! What right have we to end its life?" they respond.

What are your options?

Not many.

''You're just at their mercy, unless you want to get into lawsuits, which is not a good idea," said House & Garden magazine editor in chief Dominique Browning, who faced just this situation, and has written humorously about her wars with boundary line vegetation in Westchester, N.Y., in her book ''Paths of Desire; The Passions of a Suburban Gardener."

As with any boundary issue, passions can flare. ''In England, some neighbor just shot somebody over a hedge dispute," noted Browning. ''Which is completely insane. And completely understandable."

Though she could have legally cut off the branches extending over her property, Browning rejected this option, too, because ''you just end up with a really hideous-looking tree with all the branches missing from one side."

So instead she got a third party involved by hiring arborist Bob D'Ambrosio to act as her Henry Kissinger. ''He got a dialog going between me and my neighbor, and then he basically evaluated the tree and talked about what could be done to bring it in, and then he gave it a very, very heavy pruning." Which Browning paid for. ''It made a huge difference by reducing the size, though not as big a difference as cutting the tree down."

Stealth tree murder is a surprisingly common fantasy and an occasional fact. Those with a view to a kill are often motivated to kill for a view, especially a water view.

''People always come to me with stories about spraying trees with Round-Up at night. Down here on the Cape, we already have defoliation from gypsy moth and winter moth, so people can't tell," said Paul Miskovsky of Miskovsky Landscaping Inc. in Falmouth.

Brian Maynard, a professor at the University of Rhode Island in Kingston in the department of plant sciences, recalled inspecting one Norway maple on Narragansett Bay that was mysteriously losing leaves in the mid-summer. ''Then I looked around and saw the owner's hostas and other perennials were dying, too. The people hired a private investigator to take night photos of a neighbor spraying herbicide from his deck. I heard they had him arrested.

''Passions can run high. My uncle, the first thing he wanted to know when he found out I was a horticulturist was how to kill the black pines blocking his harbor view in Avalon, N.J. People spike trees with herbicide, spray them, girdle them, pour salt on root systems. The idea is to kill the tree without the neighbors knowing."

''In my experience, year-rounders have a better relationship with their neighbors while summer people are less considerate. They want it the way they want it," said Miskovsky. ''People have all this money tied up in their properties, and they want a view shed, which is developing a view through a hole in the foliage. Since people aren't there year round, there's some clandestine pruning in the winter. If you have someone who is trying to improve his view and it's not negatively going to affect you, you're better off saying 'yes' than coming back the next year and finding several trees missing."

There are appraisal organizations, linked to the International Society for Arboriculture, that evaluate the value of trees that have been cut or killed on someone else's property. Evaluation is based on a formula that starts at $27 per square inch of cut surface at a 4-foot height. However, it varies with age, condition, and species. For more on this, visit The American Society for Consulting Arborists site at asca-consultants.org.

Entire trees rarely fall on neighbors' properties, but when they do it's considered an ''act of God," like a tornado. The victim's insurance pays for damage to structures. However, the cost of tree removal is often considered ''maintenance" and not covered.

An exception is if the tree is in dangerously poor health, especially if the neighbor has complained to the tree's owner about the threat before it falls. Maynard was involved in one case a decade ago where an old sycamore fell on a neighboring Lion's Club flea market in Rehoboth, paralyzing a woman. The court awarded the victim $3.5 million, he said. ''The sycamore was decayed through the base 90 percent and was basically dead. The people who owned the tree had probably not realized it but they should have known it was dangerous. It was sad for both sides."

''More recently owners are being held to a higher standard. Arborists are often called to give opinions on the health of trees in such cases where the liability is in dispute," said Brian McMahon of Natural Tree and Lawn Care in Avon. ''It is worthwhile to have your trees inspected regularly to be sure that there are no hazards. It is also a good idea to scrutinize your neighbor's trees as well. Be sure to make your neighbor aware of any problems that exist before they become your problems."

Roots can also cause damage. Many extend far beyond the canopy of the tree. Susan Ruderman recently sold a Jamaica Plain house whose garage has been rendered out of plumb and unsafe at least partly due to pressure from a neighbor's tree roots on an abutting embankment. ''I am convinced that the falling retaining wall was the main reason I didn't get the asking price for the house," she said.

George Ackerson of the consulting firm Horticultural Technologies Inc. has seen cases where roots have broken through a cement foundation into the cellar, but added that the problem starts with a fault in the foundation. ''Usually roots don't grow into a solid foundation. They don't come equipped with drills." The solution here is to use a backhoe to sever the roots and excavate the foundation so you can fix it, or it will happen again, he said. As with overhanging branches, you have the legal right to cut organic material that has breached your property, but only at your own expense, and only if doing so won't kill the tree.

Hedges can also cause problems. Maynard testified a couple of years ago in a case involving two feuding McMansion owners in Charlestown, R.I., overlooking Block Island Sound. ''One person had planted a spite fence. He even hired a helicopter to chart where to locate it to block the other guy's view. He lost the case and had to cut off the shrubbery at a height that would not obstruct the view, and [had to] pay the legal fees."

More common are those schizophrenic hedges along boundaries, where one side is kept neatly pruned while the other side goes wild.

''Boundary hedges should never be shared," advised Louis Raymond of Renaissance Gardening Limited of New York and Hopkinton, R.I. ''If you want to plant a hedge, plant it far enough inside your property line that it's still all on your property even when it's at your intended height and width. That way, it's all under your control. When it's small, it could seem that you had ceded a good 3 or more foot-wide strip of your property to your neighbor. You might mulch from your hedge to your property line. The strip gets narrower and narrower as the hedge thickens, until it disappears entirely as the hedge meets your neighbor's property line."

But what if you're already sharing a hedge?

''The neighbor who wants it neat usually pays for pruning the whole thing," said Miskovsky.

Whenever possible, plant all of your privacy horticulture entirely on your own property. If you don't want to look at the neighbors, don't plant a tree at the property line and wait for it to grow tall. Instead, plant it near your house or deck where it blocks the line of sight, suggests Tom Strangfeld of the Massachusetts Horticultural Society in Wellesley. A small tree close by is as effective at screening as a tall tree far away, and provides instant results.

Garden-variety tree problems rarely make it to court because the legal costs are so substantial, said Boston real estate lawyer Linda G. Jason.

''If people are really intending to stay in their homes, they should try to resolve problems in ways that repair their relationships, which legal proceedings tend to exacerbate," added Gail Packer, executive director of the Community Dispute Settlement Center in Cambridge. She recommends going to a mediator. Unlike an arbitrator who imposes an opinion, a mediator helps parties reach agreement, which becomes legally binding when signed.

Other nonprofit regional community mediation centers around the state with sliding fee scales include Metropolitan Mediation Services in Brookline, Framingham Mediation Services, North Shore Community Mediation Center in Salem, Quabbin Mediation in Athol, the Greater Brockton Center for Dispute Resolution, the Somerville Mediation Program, Berkshire Mediation Services in Pittsfield, the Community Mediation Center in Worcester, Springfield Dispute Resolution Services, the Martha's Vineyard Mediation Program in Vineyard Haven, the Cape Cod Dispute Resolution Center in Hyannis, Northern Central Court Services in Fitchburg, and the Mediation and Training Collaborative in Greenfield.

Of course, the best solution to boundary issues, said Raymond, ''is to be on cordial terms with your neighbors, so that you can work out the details collaboratively, not adversarially."

Or as Miskovsky put it, people should learn to bend more. Like trees.