Fast becoming the mulch of choice for many landscapers due to their varied textures, colours and size, these decorative pebbles are turning up in gardens all over the world. And why not? They're natural, can quickly transform a garden area and are basically maintenance free. Plus, they don't need to be renewed - so long as we don't take fashion trends into account.

So what could possibly be wrong with gardeners utilising these natural resources?

Two reasons, really. Firstly, most decorative pebbles come from a finite source - ie. that being the rivers of the world. What has taken hundreds - maybe thousands - of years to cultivate through erosion of larger rocks will take the same amount of time to replenish. However, at the rate that the world is excavating these for home gardeners there will be a lag of a few thousand years before the next harvest is ripe.

The second reason is far more concerning. These pebbles play an important part in our river systems. While they get tumbled and smashed against each other or larger rocks on their descent therefore producing more silt, it is actually the silt that they hold back from moving too fast through the river.

If you take these river stones out of the equation then silt can become a problem further down the river. Increased levels of silt can bring a heap of problems as it builds within the river delta. The sheer volume can increase water temperatures killing fish and producing algae that destroys the life within these rivers.

And the effects are irreversible.

While it may not effect your backyard it is having, and soon will have, devastating consequences in developing nations where these are sourced. Counties such as China, Vietnam, Thailand and India are the big exporters and while the price is high these countries will always put economic gain ahead of their future environmental welfare.

What can be done about this?

Firstly, if you plan to use decorative pebbles in your landscape then buy them from a producer that sources them from less important rock specimens. If they come from a river bed somewhere they will always be doing the environment harm. Yet, if they are produced as a byproduct of mine tailings or sourced from rocks that have little impact on the earth's structure then they will be far more appropriate.

Even better than the first option is not to use them at all. Stick with organic mulches that are readily renewable and are much better for your garden soil anyway.

Decorative pebbles may be the current landscaping trend but is the cost worth the aesthetic appeal?