wildlife eco chapter 13 - wildlife and rangelands

Define rangelands and give some examples

47% of the world's land (US = 1/3); areas not cultivated (used for livestock and wildlife); management practices center around (conserving the integrity of the grass land systems)

ex) desert scrub, tundra

Why can grasses be grazed? (hint: think of where the plant growth occurs)

Agrostology: study of grasses (growth is the key to why grasses can be grazed; meristem is below ground); grazing stimulates growth (high ratio of vegetation to reproductive tissues; leaves grow FAST: carbohydrates stored; resistant to grazing); timing of grazing: wait until the END of the growing period (but then the grass is not as nutritious)

Know the animal unit (AU), some equivalencies of various species, and a major problem of the AU concept - be able to calculate specific carrying capacities, given each species' AU equivalent

AU = standardized measures of grazing pressures

1 AU = 1 cow (calf) = 1 horse = 8 white-tailed deer = 5 sheep = 6 goats = 10 pronghorn

AUs do not consider different grazing pressures

What questions should be asked when managing rangelands?

-should it be irrigated?

-what is the quality/quantity of available forages?

-what species of forage are available (palatability, nutritional content, adaptability to local conditions)

Know, in detail, 3 ways of removing brush and the effects of each method, and how to minimize damage from each method

mechanical:

depends on soil and plants; shredding, roller chopping, root plowing, chaining; estimate the effects on food/cover; other plants can increase (cacti); changes the plant's form (decreases canopies, regrowth of succulent parts); reduced cover (20% down to 4%, decreased birds (10 to 4 species), increased mammal numbers, but not species, decreased deer: no cover); DO NOT remove brush droughts

herbicides:

attack broad-leaved plants (forbs), not grasses; decreased forbs = fewer wildlife (white tailed deer decreased 60%, turkey not affected b/c they are generalists, decreased javalina, pheasants); recovery time = YEARS; to minimize damage: (not spray near reproduction areas; spray in irregular patterns, < 30 m wide; leave untreated 100 m strips; don't treat where cover < 20 %)

fire:

meristem (below ground) is protected; rapid regrowth of grasses, which produce seeds; increased grass palatability, nutrition, protein; suppress fire? (increased woody growth); management: you must know local conditions to properly use fire

Why and when should brush be managed?

many wildlife species graze on rangelands; there is an equilibrium between forbs and grasses

How do livestock change the relationships between animals and grasses?

livestock change the equilibrium between forbs and grasses

change the vegetation composition: decreased nutrition, palatability

change shape of plants: fewer high plants, lower densities of high grasses, less hiding for fawns, decreased cover for quail

How do rangeland conditions affect the quality of wildlife?

white tailed deer: spike antlers b/c of poor nutrition; food habits depend on (the season, regional differences in vegetation, different parts of the plant are eaten)

Describe how cows, sheep, and goats compete with wildlife, particularly deer

depends on the species involved:

-->deer vs. goats: browse all year

--> deer vs. sheep: forbs (especially in winter and spring)

--> deer vs. cows: browse vs. grass

Summer is a critical season in SW TX --> less food, less rain, fewer deer

Ex: deer vs. sheep vs. cows

--> winter: browse (deer vs. sheep)

--> summer: forbs (deer vs. sheep)

--> summer: grasses (cows vs. sheep)

--> best for deer? cows only

Define "rangeland condition" (NOTE: know that you measure what COULD be in a rangeland versus what IS in a rangeland - you want the actual to be as close as possible to the potential)

describes an evaluation of the current status of rangeland vegetation

--> how much does the vegetation deviate from the potential?

--> what % still represents the climax vegetation?

Decreaser: climax vegetation, preferred

Increaser: lower quality (increases with grazing)

Invaders: decreases carrying capacity

What are some effects of overgrazing?

--> decreased vegetation

--> decreased soil

--> decreased water

--> decreased carrying capacity

--> increased grasshoppers

--> prairie dogs vs. cattle? (NO b/c they eat different plants at different times of the year, NO competition)