The previous post by Marianne Cicala about tree roots destroying an earthen fill dam is SPOT ON! Do not do that. Ideally an earthen dam will be built with water impervious soil (e.g. heavy clay) on the wet side and porous material e.g. (sandy gravelly soil on the dry side. The idea is to prevent the dam from accepting water on the pond side but drain dry on the down hill side. But with respect to trees on the dam, any trees on the dry side will be stimulated to drive roots clear through the dam which will make leak paths that will cause washouts in the dam as the water follows along the root, especially if the root dies and breaks down. One very effective solution is to instead plant RUNNING Bamboo on the dam. I capitalized the word "running" because you will want a plant that spreads and invades any places that are damaged.
The reason for calling for bamboo is that it tends to be a shallow rooting plant and will not invade water as persistent submersion kills the roots. The bamboo is no wuss when it comes to roots, but its growth pattern is to establish a dense network of shallow roots
that will tie the surface together with a mat that erosion would be hard pressed to disrupt. The bamboo growth will be rapid reaching heights of 20 to 40 feet in a few years and so dense that it will shade out any tree saplings that would endanger the dam by growing quite large and pushing water seeking tree roots through the dam. Running bamboo has an undeserved bad reputation because it so vigorously spreads itself. However if one merely mows the boundaries of the grove every spring when the stuff sprouts, that is all that is necessary, just make sure that the boundaries are accessable. However as bamboo roots cannot endure constant contact with water or saturated soil it will not invade your pond.
The variety I grow can reach heights of 40 feet in places like Florida or the Gulf coast, but here in SW Missouri, zone 6 the climate keeps it at about 25 to 30 feet (at the most) and growing so thick that one cannot see through a 10 foot wide grove. It is also a wonderful wind break to reduce evaporative water loss from the pond. Even better in my case since I live on a gravel road, it is a fan tastic dust barrier, But it seems to have a quirk that it will simply not cross a gravel road. And the quirk to that is it can possibly succeed in crossing a paved road by putting out roots under the pavement. The rhizomes can grow to lengths of 1 to 1.5 times the tallest stalks (aka culms) in the grove, but as previously mentioned if a rhizome trys to extend the grove, it will put up shoots in the spring that are easily taken off with an ordinary lawn
mower, and the rhizomes can be cut with a shovel at the edge of the grove and it the sprouts are mowed off the rhizome beyond the cut will die. The rhizomes it uses to spread look for all the world like a bamboo stalk growing horizontally just under the ground with clusters of roots at the nodes instead of clusters of leafy stems. But do not plant next to a building or or where you cannot mow on all sides to prevent spreading. Of course
if it is exposedd to various animals such as horses cattle or goats, you may have to limit their access as they love it. As it is in leaf all year it makes great winter forage but you may have to fence it as ruminants find it delicious and goats seem to have an especially voratious appetite for it. Of course if you have trimmings from it, there is no need to work to dispose of it, just dump the trimmings where the goats can get at it and stand back.
The variety I am growing is Phylostachys Aureo Sulcatta, and if you do not speak Latin that translates to "leaves like corn, golden groove" and its common english name is Yellow Groove bamboo. The bamboo is quite decorative and graceful, but if you plant it next to your neighbor's fence you had best make a deal with your neighbor about mowing any invasion of his property or put down a root/rhizome barrier to stop its advance in that direction (of course along side his cow or goat pasture, there should
be no problem at all.
It seem that every year or two I find that I plant more of it for privacy or wind break or other reasons, and I now have developed fairly easy techniques to dig plants from the edges of my groves for planting and have refined the tools and techniques to make that fairly easy and effective and can plant a new 100 foot long grove in about a weekend provided I have enough
of a grove to provide me with the requisite number of plants. If anyone is interested I I have plenty of pictures showing the technique and results. In as little as 2 to 3 years one can have a 6 to 10 foot bamboo wall and in 5 years a 25 to 30 foot wall. (Too bad I am not in a gulf zone where I could grow a cousin of the bamboo I grow here. It is called MOSA and a new shoot coming up in an established grove will reach its full height of about 70 feet and 7 to 8 inch diameter the first year. That is some macho bamboo !!! My quite adequate variety is lucky to reach a more modest 25 to 30 feet and 1.5 inch diameter at most around here. But there are all sorts of varieties with most any growth pattern you might want so far as size goes.
If you just want a few clumps of bamboo for landscaping, it would be best to stick with the so called clumping bamboos, but they won't spread themselves like you would want if you wanted to plant bamboo that would take over dominate, preserve and reinforce an earthen fill dam. Of course the bamboo will also stablize steep earth slopes, but in my experience
you would want to start planting near the base as the bamboo seems to advance uphill better than downhill, or at least that is my experience here with the variety I have.
You may need to check your local
laws because many urbanites seem to have gotten bamboo classified as an invasive weed because of careless neighbors and a lack of understanding of this vigorous durable plant that has many agricultural advantages. Let me know if you want to know more about this wonderful, useful plant.