Rangeland Health
Rangeland stewardship includes adopting
management practices and goals to achieve
rangeland health—the ecological condition
of the land. Three perspectives, taken as
a whole, are used in evaluating ecological
status. The overall condition of the site
is then determined by a process of “preponderance
of evidence” considering these three
perspectives:
- The first of these perspectives is the
soils/watershed function. The basis of
an ecological site's potential is its soil
resources—the condition of the soil,
particularly the upper horizons; its propensity
toward erosion; and its ability to accept
precipitation. Sites with their soils intact
are not only productive in their ability
to support plant growth and development,
but also are able to capture raindrops
where they fall (infiltration) to augment
soil moisture, rather than allowing this
precipitation to escape from the ecosystem.
Overland flow—or runoff—not
only fails to replenish the soil moisture
on-site, but it may also erode soil from
the site as it flows across the surface
of the land.
- The second of these perspectives is the
energy flow relationships on the site.
Energy flow is a reflection of the sun's
energy that has been captured and redirected
through the process of photosynthesis.
In evaluating this component, one must
look at the existing plant communities,
their life forms, and composition. For
example, a site with a diverse mixture
of perennial plants is capable of capturing
sunlight over the entire growing season,
whereas the same site occupied by alien,
usually annual, species may see a positive
energy flow only during a brief early spring
period.
- The third of these perspectives is the
site's ability to recover from a disturbance.
Sites that have appropriate combinations
of age classes, species composition, and
plant vigor have the ability to withstand
occasional disturbances from drought, fire,
or herbivory (plant feeding). Those sites
that are low in plant vigor, all of one
age class, or lacking in community diversity
are at risk of being eliminated if and
when a disturbance occurs.
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