Changes to Rangelands Over Time Intro to Range--OBJ 4: PPT Changes to Rangelands Over Time

Intro to Range--OBJ 4: PPT 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 Grasses Woody Plants

Location of Growing Points - Grasses Range Plants -- OBJ 2: PPT Location of Growing Points - Grasses Also called: Buds Meristems From: How Pasture Plants Grow by Stephen K. Barnhart; Iowa State Cooperative Extension There are 16 slides in this presentation

Location of Growing Points - Grasses Range Plants -- OBJ 2: PPT Location of Growing Points - Grasses You can use an example of how lawn grass looks ragged soon after mowing – not a smooth topped looked like after mowing. Plant pushes new growth from the base of the plant, pushing old growth upwards. Grasses “push” growth from the growing point --- old growth at tips of leaves There are 16 slides in this presentation

Range Plants -- OBJ 2: PPT 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. For grasses, when you’re applying a management practice, you must be aware of the morphology of the plants in the community being treated. Grasses with growing points at the base are more resistant to fire and grazing. From National Range and Pasture Handbooks www.glti.nrcs.usda.gov/technical/publications/nrph.html Chapter 5 page 2-13 There are 16 slides in this presentation

Range Plants -- OBJ 2: PPT Location of Growing Points - Grasses Stolon Rhizome Plants that have stolons and rhizomes are more resistant to disturbance. New growth can come from below Stolons & Rhizomes There are 16 slides in this presentation

Location of Growing Points - Grasses Range Plants -- OBJ 2: PPT Location of Growing Points - Grasses Culmed Apical Meristem Culmless Culmless grasses have growing points that are more protected because they are located at the base. Plants with exposed axillary buds along the stem that can be removed by fire or grazing, they are more damaged by these disturbances. Axillary Buds There are 16 slides in this presentation

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.

Range Plants -- OBJ 2: PPT Location of Growing Points – Shrubs & Trees When you see areas that have been hedged, you know that it has been heavily browsed. Disturbances that remove biomass stimulate new growth from buds along the branches. Shrubs have defenses from grazing including thorns and chemicals that protect their buds or growing points. How well shrubs survive fire depends on if they have basal buds (e.g. mesquite) or if they have thick enough bark Forbs and shrubs initiate growth outermost points There are 16 slides in this presentation

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

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

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

Differences between fire & grazing? __ __

Differences between fire & grazing? 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 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.

Intro to Range--OBJ 4: PPT 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 Intro to Range--OBJ 4: PPT 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

Intro to Range--OBJ 4: PPT 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.

Intro to Range--OBJ 4: PPT Human Activities Include development, recreation, subdivision Humans affect 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?