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FULL QUESTION:
I have 35 acres in Elizabeth. Rolling hills, native grasslands and Ponderosa pine forest on the land. This area was logged long ago and was part of the Black Forest. My next significant native plant project is to create windbreaks that are also shelter belts for bird and insects. I have ideas for things to plant, but I feel that I should be planting guilds of trees, shrubs and forbs that would be naturally found in community on this type of topography windy, hilly, dry… I have found a lot of information on a variety of plant guilds, but nothing that would be appropriate for my land. All must be drought tolerant, but I do have the ability and expectation of irrigating them for at least the first 2 years and on occasion during our extreme drought years.
ANSWER:
First, two definitions.
Species guilds, and particularly plant guilds, are groups of species that occupy similar habitats and exploit resources in the same ways (think of 17th century guilds of artisans, all plying the same trade in the same region). Because they grow in overlapping (or nearly overlapping) niches, they are often found in the same habitats and can have competitive relationships.
Windbreaks can be excellent resources for local wildlife as well as provide energy savings and welcome relief from the wind for homeowners. To be effective, a windbreak needs to be somewhat uniform, be positioned perpendicular to prevailing winds, and extend beyond the area to be protected. Typically, multiple rows of similar plants are used to create resilient landscape features. Three- and five-row windbreaks are common in rural portions of Eastern Colorado, using deciduous shrubs, small deciduous trees, and a tall row of evergreen trees for a layered and dense landscape feature.
Especially in dry places, the health of the windbreak trees and the effectiveness of the windbreak can be at odds. In order to be effective, the windbreak must be fairly dense, with woody plants growing more closely together than what would normally be found (or supported) in nature. Care must be taken to select drought tolerant species and to plant them no closer than necessary; even then, supplemental irrigation will be required to keep the windrow healthy in dry years. Typical spacing to provide wind protection and to minimize competition for water is 12-20 feet between rows and 8-15 feet between trees and 3-6 feet between shrubs in a single row, depending on species.
On the treeless or nearly treeless plains, choosing the right woody plants can be a real challenge. For native plants mimicking what could be found along the Palmer Divide in Colorado, choices for evergreens include Ponderosa pine (Pinus ponderosa), Douglas fir (Pseudotsuga menziesii) for wetter locations or northern exposures, and Rocky Mountain Juniper (Juniperus scopulorum). Pinyon pine (Pinus edulis) and one-seed Juniper (Juniperus monosperma) are regionally native options, and even Eastern Redcedar (Juniperus virginiana), the native range of which extends into Western Kansas and Nebraska. For exposed, dry sites, the selection of native deciduous trees is limited to Gambel oak (Quercus gambelii) and Boxelder (Acer negundo), but you might consider including near-regional natives like Wafer-ash (Ptelea trifoliata). A first row of deciduous shrubs might include currants (Ribes spp), Wood’s Rose (Rosa woodsia), and Chokecherry (Prunus virginiana), or for maximum drought tolerance, rabbitbrush (Ericameria spp.), three-leaf sumac (Rhus triloba), and bigtooth sage (Artemisia tridentata).
Remember that species diversity will favor both biodiversity of other species like birds and insects and resilience of your windbreak to disease or environmental stresses.
Answer developed by: John Murgel (Extension County Specialist, Horticulture and Natural Resources, Douglas County) Colorado State University Extension.
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