Changes to Rangelands Over Time

Range Change Factors  Grazing  Fire  Invasive Species  Weather/Climate  Human Activities

Goal of ecosystem management  Efficiently capture sunlight  Reduce losses of nutrients and water from system Land managers will have more specific goals

Forces of Ecosystem Change  Immigration and establishment of plants  Competition between plants Fire Grazing  Site modification  Stabilization

How does grazing affect plants  Some plants are extremely sensitive to grazing (A)  Most plants are somewhat tolerant of grazing (B)  A few plants actually benefit from grazing, especially light grazing (C )

How does fire affect plants  Some plants are extremely sensitive to fire (A)  Most plants are somewhat tolerant of fire (B)  Other plants actually benefit from fire especially light grazing (C )

Adaptations to Fire and Grazing GrazingFire Grasses Woody Plants

Location of Growing Points - Grasses From: How Pasture Plants Grow by Stephen K. Barnhart; Iowa State Cooperative Extension Also called: Buds Meristems

Location of Growing Points - Grasses Grasses “push” growth from the growing point --- old growth at tips of leaves

Location of Growing Points - Grasses  As long as the growing point is present growth continues.  If removed - growth stops and new growth has to initiate from a dormant bud. From National Range and Pasture Handbooks Chapter 5 page

Stolon Rhizome Location of Growing Points - Grasses New growth can come from below Stolons & Rhizomes

Location of Growing Points - Grasses Culmless Culmed Apical Meristem Axillary Buds

Location of Growing Points - Grasses  Location depends on season Early in the growing season - close to the ground and protected. As the season progresses - elevates and subject to removal.

Location of Growing Points – Shrubs & Trees Forbs and shrubs initiate growth outermost points

Location of Growing Points – Shrubs & Trees Meristem J. Peterson

May have basal buds and be able to resprout form base after fire Location of Growing Points – Shrubs & Trees

Other fire adaptations – Shrubs & Trees J. Peterson fs.fed.us Insulating bark Serotinous Cones

Differences between fire & grazing? Grazing  __ Fire  __

Differences between fire & grazing? Grazing  Not selective for specific plants  Removes dead and live tissue  Produces heat  Recycles nutrients in inorganic form  Recycles nutrients in a relatively even layer across the landscape  Patchiness on a landscape scale  Most likely in dry-hot season  May create hydrophobic soil layer but, doesn’t yield compaction  Generally reduces seed viability, though some seeds require fire to be viable. Fire  Selects palatable over unpalatable  Live tissue preferentially removed  No heat produced  Recycles nutrients in organic (feces) and inorganic (urine) forms  Recycles nutrient in patches  Patchiness on a plant-scale  Occurs year round  Can cause compaction through hoof action  Generally reduces seed viability though some seeds require consumption to become viable

Weather/Climate  Most important factor in long-term changes to rangeland plant communities  Normal variation Year-to-year (annual) Long-Term  Drought  Impacts on plant composition

Exotic of Introduced Species  Definition: “plants that are not native to a region that have been brought in either intentionally or unintentionally”  Invasive vs. weed  Response to disturbance How do they increase?  Negative environmental impacts

Invasive Species  Species that that increase in a community in a way the suppresses other plants in the community and reduces there abundance or fitness.  Can native or introduced  Negative environmental impacts  Have characteristics, such as high seed production or root sprouting, that allow them to increase with disturbance.

Human Activities  Included development, recreation, subdivision  Humans affects other forces of nature Invasion Fire Grazing Climate/weather?

Current Issue of Ecological Change: The “Pristine Dream” - many environmentally concerned people wish that rangelands could return to pristine conditions similar to what Lewis and Clark observed.  Possible or Not?

Current Issue of Ecological Change: Sustainability (or Sustained-yield) is the concept that we can graze or otherwise use the rangeland resource in such a way as to not jeopardize future productivity.  Possible or Not?

Current Issue of Ecological Change: Biodiversity (or Biological Diversity) is an attribute that describes for the variety of organisms the genetic variation they contain and the variety of communities, ecosystems and landscape pattern in which they occur.  Believed that more diverse ecosystems are generally more stable and able to cope with disturbance than less diverse ecosystems.  Many agencies and environmental organizations espouse the concept that we should manage for high biodiversity. Yes or No?