RS300
Quiz
10-25-99
1. An alternate model of vegetation dynamics, the state-and-transition model, allows for more than one possible “steady state” condition. (a) true (b) true
The way we think about a system does determine potential alternatives for management. It influences our thinking about the wisdom of intervention to direct a system towards a desired state, natural or otherwise.
2. An area (High Desert of Oregon) is dominated by dense big sagebrush (30% canopy cover). Understory of perennial herbaceous plants is sparse. The area has a history of continuous, season-long grazing by cattle. (a) few changes would be expected in the next decade, assuming continuation of present management (b) after removal of big sagebrush by fire [difficult because of inadequate fine fuels to carry the fire] and removal of cattle grazing, the area would be dominated by perennial grass and other herbaceous species (c) after removal of big sagebrush by fire and removal of cattle grazing, the area would be dominated by annual grasses like cheatgrass (Bromus tectorum) and/or other weedy annual forbs (d) after removal of big sagebrush by a spring application of 2 lbs of 2,4-D per acre and grazing by cattle only in late fall, within a few years the area would be dominated by perennial grass and herbaceous forbs.
4. Colonization is (a) nudation (b) migration (c) ecesis (d) competition (e) reaction
5. Disturbance with organism (vegetation) removal is (a) nudation (b) migration (c) ecesis (d) competition (e) reaction
6. Site modification as a result of vegetation dynamics and interaction of the biotic and abiotic environment is (a) nudation (b) migration (c) ecesis (d) competition(e) reaction
7. When organisms vie for resources it is called (a) nudation (b) migration (c) ecesis (d) competition (e) reaction
8. Disturbance is a natural and important process in ecosystem dynamics and succession. All ecosystems are continuously recovering from some kind of disturbance on different spatial and temporal scales. (a) true-true (b) true-false (c) false-true (d) false-false
9. Grazing can be (a) a disturbance. (b) a facilitator of colonization. (c) a vector determining species performance.
10. One of the important effects of disturbance is release of nutrients, i.e., opening of mineral cycles. (a) true (b) false
11. Noxious weeds like leafy spurge and Russian knapweed are threats to diversity on rangelands. (a) true (b) false
12. We talked about abiotic vs nutrient limited systems. What does that mean in regard to the way systems are organized? No response required now, but later…
RS300
Quiz
10-25-99/10-27-99
1. Plants that occupy areas following drastic disturbance often are opportunistic; they establish and survive under conditions of excess free nitrogen. (a) true (b) false
2. Organic material that moves through the decomposer vs grazer pathway turns over at a slower rate. More soil N is made available to growing plants. (a) true-true (b) true-false (c) false-true (d) false-false
Less soil N, because most locked up in plant and litter organic matter.
3. In late seral stages more energy is transferred through the decomposer than the grazer pathway. (a) true (b) false
This might be more by definition than real world.
4. Disturbance closes mineral cycles. (a) true(b) false
5. Disturbance is a natural and important process in ecosystem dynamics. (a) true (b) false
Usually, greatest diversity in areas with intermediate disturbance or recovering from intermediate disturbance.
6. I was recently in France where I visited a rangeland in the 600 mm precipitation zone. The area supported motts or clones of some species of oak. The understory was near continuous ground cover of perennial bunchgrasses. I noted extensive areas of recent disturbance by wild pigs (most on the order of 10 m2 to 100 m2 in size). As a naturalist, I should be concerned to see this kind of disturbance; it is ultimately detrimental to sustaining the intrinsic attributes of the system. (a) yes (b) no
I might be disturbed by the presence of feral pigs. It might be outside my value system to see that kind of disturbance. The system doesn’t care. Of course, too many, too often without opportunity for the system to recover could have negative impacts on associated plant and animal species.
7. See 6: I expect the next plants to occupy these disturbances will be (a) annual forbs (b) perennials represented by the surrounding vegetation (c) oak trees
The next plants will be annuals, but early seral perennial grasses and forbs should re-colonize within a decade under that precipitation regime.
8. See 6: You would recommend immediate reseeding with native grasses and forbs (hint: look at the spatial scales involved). (a) yes (b) no
Scale is small enough propogules for re-colonization should be readily available.
9. At a given seral stage, all rocky foothills range sites in a region have the same percentage above ground plant composition by weight. (a) true (b) false
The same plants in about the same portions, but not the same.
10. Mineral cycles are said to be closed when biogeochemical cycles are “tightened,” i.e., the system entraps and holds nutrients for cycling within the system. (a) true (b) false
11. Mature ecosystems exhibit (a) good (b) poor nutrient conservation.
The system is not “leaky.” [not sure who thought up that term, but you see it in the ecological literature a lot] Nutrients are ited up in organic matter both above and below ground.
12. At mature stages of community development, gross productivity per unit of standing crop biomass is (a) low (b) high
13. Mineral cycles are said to be open when biogeochemical cycles are “leaky,” i.e., nutrients are lost from the system either through leaching, volatilization, overland flow, etc., or uptake by N-opportunistic plants. (a) true (b) false
14. At late seral stages of community development, RT is high and (N)et (C)ommunity (P)roductivity is low or zero. (a) high (b) low
15. A plant community that supports mid seral plants can possibly be “transitioned” to a late seral stage by removing grazing [more than one correct answer possible] (a) depends on initial conditions, i.e., the mix of plants that currentlyoccupy the site (b) depends on the reason a plant was able to occupy the site, e.g., sagebrush (c) depends on soil-plant-water relations after removal of grazing
16. Nitrogen cycling and uptake in grazed plants is(a) more (b) less than ungrazed plants.
17. Remember that stuff back early in the semester by Odum on characteristics of developing and mature ecosystems. Go back and look at it. Also, the table from Odum on characteristics of stressed ecosystems.
RS 300
Quiz
10-29-99
1. Colonization refers to plant recruitment into a gap (an open space) by means of seed or vegetative reproduction. (a) true (b) false
2. At a given seral stage, all shallow overflow range sites in a region have the same percentage plant composition by weight (aboveground biomass). (a) true (b) false
3. Management of natural resources is adaptive, that is, it allows the decision maker the possibility of gathering information as the successional horizon (time) unfolds. (a) true (b) false
4. The situation is an expansive area (several square miles) that supports early seral vegetation. The area has been in this seral stage of development for at least two decades. (a) free nitrogen in the soil is probably high (b) rate ofcolonization by native plants is nil because of lack of available seed source and a vector for moving the seed on to the area (c) should be burned in order to “speed up” rate of succession (d) needs some type of management that incorporates N into recalcitrant forms of biomass or removes nitrogen from the system (e) this is an abiotic controlled system
5. Facilitation is (a) early successional species establish, initial colonists modify the environment so that late-seral species cannot establish and then late seral species establish only when early seral species die (b) early seral species establish, initial colonists modify the environment so it is more conducive to late seral species, and late seral species invade and establish dominance (c) early and late seral species establish, early seral species modify the environment to exclude other species, and late seral species tolerate the competition and assume dominance.
6. Inhibition is (a) early successional species establish, initial colonists modify the environment so that late-seral species cannot establish and then late seral species establish only when early seral species die (b) early seral species establish, initial colonists modify the environment so it is more conducive to late seral species, and late seral species invade and establish dominance (c) early and late seral species establish, early seral species modify the environment to exclude other species, and late seral species tolerate the competition and assume dominance.
7. Tolerance is (a) early successional species establish, initial colonists modify the environment so that late-seral species cannot establish and then late seral species establish only when early seral species die (b) early seral species establish, initial colonists modify the environment so it is more conducive to late seral species, and late seral species invade and establish dominance (c) early and late seral species establish, early seral species modify the environment to exclude other species, and late seral species tolerate the competition and assume dominance.
RS300
Quiz
11-03-99
11-05-99
1. Species performance can be altered by selective grazing, i.e., manipulating both the kind of grazer and timing of a grazing event (a) true
2. I go to an area. The area is dominated by plants (like annual kochia) that are characteristically known to have luxury uptake of N. I am probably looking at a system in (a) early(b) mid to late seral stage.
3. Plants that colonize and dominate an area following drastic disturbance often have very inefficient mechanisms to conserve nitrogen (a) true (b) false
4. Once a system forms a stable state (stabilization in Clementsian terms), processes are quite fixed and the attributes of the system vary little among years. (a) true (b) false
5. Generally, plants found at later seral stages are longer lived than those at earlier seral stages. (a) true (b) false
6. I want to revegetate an area (15″ growing season precipitation) that is predominately made up of very fine sandy soils near Imperial, Nebraska. It is dominated by annual cheatgrass (Bromus tectorum) or nothing in some parts. Wind erosion is an issue. In order to manage risk of failure:(a) I could spray in late April with 2 lb/acre glyphosate (Roundup) and seed the area using a seeder with double disk openers and depth-control bands.
This is probably my best shot. I keep residue on soil and kill competing vegetation. I might add a little sandlove grass just to get some kind of perennial cover.
(b) I could plow in spring, plant a sorghum cover crop in June and seed into the cover crop with a rangeland drill before May 15 of the following year
Not a bad idea if soils were more stable. But, here it would be very risky to remove cover, even for a very short time. Then, what if the sorghum failed?
(c) I could broadcast a seed mix on the area in late November.
Not the place for broadcast seeding. Sand does not make adequate contact with seed even under best of conditions.
(d) leave it alone; it will recolonize to native species on its own in less than a decade.
Maybe. depends on availability of seed. It might take a long time.
7. Figure 10-2 in Heady and Child show that “added minerals” vis-a-vis fertilization would move a system toward climax. Does that seem reasonable? (a) yes (b) maybe not
8. Figure 10-2 in Heady and Child show that “introduction of new herbivore into a system” would move the system away from climax. Does that seem reasonable? (a) yes (b) maybe or maybe not; it may only result in shift in speciescomposition because different animals alter the species performance of different plants but do not materially alter ecosystem attributes.
9. Figure 10-2 presents succession as an orderly process that responds positively to time and water and negatively to grazing pressure (the assumption is a single steady state – climax). (a) true (b) true
But, it doesn’t make it right. Does not distinguish between water and nutrient limited systems. Assumes succession is linear. It is not.
RS300
Quiz
11-05-99
1. Understory herbaceous vegetation is often nil in mature stands of Pinon-Juniper (conifers) because the P-J furnishes severe competition for nutrients, light and water. (a) I think that is generally true
2. P-J that burns on a regular schedule usually coexists with a good (for the conditions) herbaceous understory of shrubs (e.g., big
sagebrush), bunchgrasses and forbs. (a) I think that is generally true
3. Burning volatilizes N to the atmosphere. (a) true (b) false
4. When shrubs and trees are killed. nutrients (especially N) are released in the soil because of microbial activity on below ground organic matter, (a) true (b) false
5. (a) Early seral plants (like, annual forbs or annual grasses) (b) Late seral grasses quickly colonize areas with abundant free soil NO3 nitrogen.
6. Late seral species usually dominate on soils low in free nitrogen. (a) true (b) false
7. Plants that occupy areas following drastic disturbance often have very efficient mechanisms to conserve nitrogen and perpetuate the individual plant (a) true (b) false
8. Ecosystems tend to be most stable, i.e., less variable, at (a) late (b) early seral stages
9. It is not possible to manage a mixed grass rangeland type in “fair condition” and expect that system to be sustainable. (a) true (b) false
10. Fire can be (a) a disturbance (b) a facilitator of colonization (c) a vector determining species performance.
11. Species performance can be altered by selective grazing (a) true (b) false
12. In general, belowground biomass in rangelands throughout the world (a) increases (b) decreasesas environmental conditions become more mesic.
X. Given the following: a site is dominated by big sagebrush with a sparse understory of herbaceous plants. One hot, and very windy day, a lightning strike started a fire. The fire moved rapidly.
13. At this point mineral cycles were (a) opened (b) closed
14. You expect the area to be colonized by (a) bluebunch wheatgrass and Idaho fescue, native late seral perennial bunchgrasses or (b) cheatgrass, an alien annual grass that readily germinates in the fall, winter and spring.
If perennial grasses are present in the stand, they will not go away. Cheatgrass will compete for water; thus, lower productivity possible.
15. Removal of cattle grazing pressure would facilitate the recolonization of perennial, late-seral grass and slow the recolonization of big sagebrush. (a) true (b) false
Sagebrush is a disturbance plant and when conditions are right it will re-colonize, regardless. Removal of cattle grazing pressure would slow the turnover of N and make less available to annual plants. But, it may or may not facilitate re-colonization.
16. Heady and Child suggest the difference between natural and human disturbances is the frequency and intensity of change [note Heady and Child use a different definition of disturbance than Rittenhouse] . (a) I read it on page 132 (b) not sure, but I’ll read some of that before the test
17. For germination and establishment most rangeland plants require a seeding depth of at least 2 inches (50 mm). (a) true (b) false
Most range plants should be seeded very shallow; they are usually very small seeds.
18. Best seed germination and seedling establishment occurs on a prepared seedbed, including packing of soil to ensure seed-soil contact. (a) true (b) false
That doesn’t mean you can’t obtain acceptable results with less than perfect conditions; just the risk of failure increases.
RS300
Quiz
11-08-99
1. Xeric is a relative term that means dry (a) true (b) false
2. Let’s say you chose the alternative of seeding in those areas dominated by annual forbs. What would be your criteria for success? (a) 1 established plant per ft2? (b) 25 plants per ft2? (c) 100 plants per ft2?
3. Let’s say you chose disk plowing to remove the crested wheatgrass. The plants probably would not be killed; they would come back from tillers. (a) no (b) yes
4. Let’s say you chose a herbicide to kill crested wheatgrass. Which would be a better choice (a) 2,4-D? (b) glyphosate? (c) tordon? [why?]
It is a non-selective herbicide. Actually, I might want to use a pre-emergent herbicide.
5. Let’s say you chose a herbicide to kill competing annual forbs following seeding. Which would be a better choice (a) 2,4-D? (b) glyphosate? (c) tordon? [why?]
2,4-D and Tordon are selective, broad-leaf herbicides. 2,4-D is cheaper; tordon has much longer soil residual.
6. Let’s say you decide to seed the whole area, 1380 acres. How many total pounds of bulk seed would you need? (a) 50 lb? (b) 500 lb? (c) 5,000 lb? (d) 50,000 lb?
7. Let’s say you decide to do nothing in the annual forb area. How long will it be before the annuals are no longer dominant? (a) 5 years? (b) 25 years? (c) 100 years? (d) 1,000 years
8. Let’s say you decide to make annual applications of nitrogen fertilizer at 30 lbs per acre. How long will it be before the annuals are no longer dominant? (a) 5 years? (b) 25 years? (c) 100 years? (d) 1,000 years
9. Mesic is a relative term that means dry (a) true (b) false
10. The diversity of organisms in an ecosystem is often highest at some intermediate level of disturbance, because organisms of both early and late seral stages occupy the site. (a) true (b) false
11. A plant community that supports mid seral plants can probably be “moved” to a late seral stage by removing grazing [more than one correct answer possible] (a) depends on the mix of plants present (b) depends on reason a plantwas able to occupy the site, e.g., sagebrush (c) depends on soil-plant-water relations after removal of grazing
12. Management can “control” the successional trajectory (i.e., the transition) toward a later seral stage by doing those things that direct most of the organic matter through the decomposer pathway or sequester nutrients in recalcitrant tissue, like wood or roots that turn over slowly. (a) true (b) false
13. Structure and function of plant communities tends toward a stable state because of negative feedbacks (they damp-down change) in the system.(a) true (b) false
14. Soil texture is determined by the composition of sand, silt and clay size particles. (a) true (b) false
15. Ecosystems at (a) late seral (b) early seral stage can withstand the greatest perturbation without causing a transition to a new state.
16. Disturbance refers to the removal of organisms from the system. (a) generally accepted by ecosystem ecologists
RS300
Quiz
11-10-99
I read the following in THE FURROW entitled “Farming Prairie Crops.” The land owners name was Kurtz. Basically, Kurtz is producing seeds of prairie plants for sale to distributers.
“Don’t apply nitrogen on prairie plants,” Kurtz adds….. Does that sound like a good idea? Why or why not?
He has the right idea [if you were to read the remainder of the article his reasoning is a bit off base] Most of the plants he is trying to promote are late mid to late seral plants, especially the grasses.