Short Answer Questions for Rangelands

How does climate affect vegetation patterns at the level of biomes?

It influences biomass production and the type of vegetation, like drought adapted plants in deserts, and herbaceous plants in grassland.

What is the Hadley Cell effect?

Dry air picks up moisture while it moves towards equator (desert). Then rises, causing rainfall (rainforests) and hits the atmospheric ceiling, cooling, and then heading back north.

Explain why rain shadows occur on the down wind side of mountain ranges

when moist air is forced to rise over the mountain, it cools and condenses, releasing precipitation on the windward side

Explain what has happened to plant succession theory

Plant succession theory (also known as equilibrium theory) was originally adopted as the foundation of range science, however, it has since been challenged by non-equilibrium ecology which accounts for alternative stable states in rangeland ecosystems (e.g., grassland conversion to woodland).

Explain why stocking rate is considered the most important grazing management decision?

Stocking rate balances supply and demand, so the wrong rate could lead to over or under grazing. It drives the vegetation community.

Explain the rationale between the take half, leave half grazing management decision

The take half leave half grazing management decision states that 50% of the forage on a piece of land is used. The other 50% is used for photosynthesis, litter, wildlife, habitat, and soil protection from wind erosion. Of that 50%, 25% is actually eaten, which is the harvest efficiency.

Explain the difference between overgrazing and overstocking.

Overgrazing is over a long period of time and involves heavy grazing that results in damage to plant community and can happen when land is overstocked for too long or too frequently. Overstocking is over short periods of time and may or may not result in overgrazing. Land managers use overstocking to reach management goals.

Explain how a rangeland manager could manage the distribution of cattle over time to ensure that the same areas are not grazed during sensitive periods year after year. (1-4 sentences)

Use patch-burn grazing to drive changes in cattle distribution over time.

Use a rotation system to provide pasture with rest.

Fence off areas that were grazed during sensitive times in previous years.

Explain how the interaction between fire and grazing can increase the complexity/diversity of rangeland vegetation structure in the Great Plains

Patch-burn grazing results in a patchy structure in grasslands where patches range in structure from open habitats (recently burned areas) with little cover to dense plant cover (patches with longer times since fire).

Explain why complex/diverse structure in rangelands is important for grassland bird diversity

Different bird species have different habitat requirements and so diversity in grassland structure supports more species than simplified rangelands that accommodate a narrow range of habitat requirements.

In the range model, describe the relationship between successional stages and range condition. As a community moves from early successional stages to late successional stages, how does range condition change.

At the beginning of early successional stages, or the pioneer stages, range conditions are poor. As time goes on and a vegetation moves towards the climax and late successional stages, range conditions become better, reaching its best at the climax.

How is grazing intensity applied in the range model to achieve a desired range condition?

Grazing intensity is high at early successional stages, when range conditions are poor. Intensity is low when range conditions are excellent in the late states of successional theory.

Proper grazing management has resulted in a phenomenon referred to as 'managing for the middle'. Describe this phenomenon and what influence it has had on rangeland plant communities.

Managing for the middle is when moderate grazing intensity or stocking rate is applied because this is economically optimal. This has caused the simplification of rangeland vegetation because most communities reflect mid successional stages.

Managing for the middle' has had a negative impact on grassland bird diversity (True or False; explain the reasoning for your answer).

Managing for the middle' has had a negative impact on grassland bird diversity (True or False; explain the reasoning for your answer).

The range model was replaced as the foundation of range management by resilience theory and non-equilibrium ecology. Describe one shortcoming of the plant successional model in range management.

One shortcoming of the plant successional model in range management is that it assumes linear progression of vegetative communities towards a climax. This often doesn't reflect the reality of vegetative rangeland ecosystems, making it difficult to manage based on just ideal vegetative composition.

Provide an example of a win-win interaction between ecosystem services in rangelands.

Grazing National Wildlife Refuge. Habitat management, livestock production, and invasive species regulation all benefits.

Provide an example of a trade-off interaction between ecosystem services in rangelands.

Afforestation of rangelands. Wood supply benefits, however water supply depletes.

Explain one reason why managers set stocking rates below carrying capacity in rangelands.

Accounts for low production years and avoids overgrazing.

Ecological resilience is defined by

the capacity of systems to absorb disturbances and reorganize while undergoing change so as to still retain essentially the same function, structure, identity and feedbacks.