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Functions
& Conditions -
Woody Draws
Woody draws
are prominent features across eastern Montana and elsewhere in the
Great Plains (Figure 2-28). In many cases, these areas do not meet
the strict definition of a wetland because water may not be present
long enough each year to create anaerobic soil conditions. Nevertheless,
they clearly perform some of the functions of riparian areas, and
most of the characteristics for determining the health of a riparian
area can be applied to woody draws. Moreover, their importance,
both ecologically and economically, makes them among the most valuable
resources on a ranch.
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Figure
2-28
The location of woody draws, surrounded by drier, less
diverse uplands, makes them critically important for
properly functioning ecosystems. |
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The water, both
surface and sub-surface, which collects in these draws enables them
to exhibit different and much more varied vegetative communities
(Figure 2-29) than exist in the surrounding uplands. Thus, woody
draws provide critical elements of habitat--including cover, food,
and water--for numerous animal species. In many cases, these animals
could not exist without these special zones, even if they get only
part of their needs from them. In addition, livestock rely on both
the vegetation and the topography of these areas for protection
against climatic conditions, especially during winter storms.
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Figure
2-29
The luxuriant growth inside this woody draw indicates
a well-managed, healthy plant community. |
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Given their
importance, it is essential that ranchers incorporate woody draws
into grazing management plans and pay close attention to maintaining
or improving their condition. Of particular concern should be the
presence of all age classes rather than just mature woody species,
including box elder, green ash, and American elm. The grazing management
techniques we will address in the next lesson apply to these ephemeral
woody draws as well as to intermittent and perennial systems.
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