É um termo geral, mas espero que ajude...
Película também pode ser uma opção, embora não me pareça tão adequada para este contexto.

This is it. The aim is to protect against bugs and other pests:

Landscape Fabric and Mulch
Landscape fabric (or geotextiles) can play a valuable role in various applications for weed control. including shrub beds, tree wells, and other mulched or gravelled areas. Since landscape fabric is usually included "within" a feature (e.g., under a layer of mulch and around ornamental plantings in a shrub bed), it is highly preferable that they are installed during the initial construction of the feature. However, they can also be retrofitted to many landscape features. Geotextiles can provide significant benefits by reducing maintenance requirements and the need for herbicide use for weed control. Proper material selection and installation procedures are important to ensure the effectiveness of geotextiles.
Thermally spunbonded fabrics are much more effective than woven or needle punched geotextiles in preventing fine roots and rhizomes from penetrating the fabric. Heavier weight fabrics should be used for sites that do not have frequent maintenance intervals. When installing geotextiles, potentially damaging objects (i.e., large angular rocks; pointed sticks) should be removed from the site and the soil should be graded so the fabric will lay smooth and flat on the ground. Where potentially difficult to control weeds are abundant (e.g., quackgrass), an herbicide may be desirable or necessary to prevent weeds from growing to and through seams and edges from below. In some settings, a shallow trench (2"-3") around the perimeter of the installation site is helpful to hold the edges in place and keep them from becoming exposed. Seams should be overlapped 6"-8" and the fabric should be tightly fitted around any objects. Where fabrics may become exposed and subjected to vandalism they should be pinned firmly to the ground, especially around the perimeter. The fabric should then be covered with 2"-3" of mulch because ultraviolet light is damaging to most geotextiles and they should always be adequately covered. When properly installed, geotextiles will last indefinitely.

A disadvantage of using landscape fabric in shrub beds, tree wells, and other ornamental plantings is that the soil under the fabric becomes relatively inaccessible, making it difficult and time consuming to add amendments for soil improvement. However, this problem can be alleviated by adequately preparing the soil before the fabric is installed.



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Note added at 9 mins (2004-08-04 20:38:19 GMT)
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I meant \"protetor\" do terreno, not \"protetot\".