Fire destroys the seeds of many types of chaparral shrubs

Agricultural practices can pose a challenge to survival of native species    Question 3 options:   True   False

Which of these hypotheses does not explain why increased CO2 levels in the atmosphere could cause a decrease in the productivity of some crops because of changes in climate?   A) There could be increases in average winter temperatures that reduce the growth of crops. B) There could be decreases in precipitation in some regions that reduce growth in some crops. C) There could be shifts in the ranges of some important species in the community, such as pollinators, that cause reduction of growth in some crops.

(a) 10% Woody Cover (b) R-0.24 8 P=0.01 5 20 30 50 Years After Abandonment 10 0 0 00 0 0 30 35 40 Degrees Latitude 45 50 30 R-0.34 P<0.01 50% Woody Cover Years After Abandonment 10 20 30 50 5 8 30 35 40 Degrees Latitude 45 In eastern Ohio, most climax communities are forest, defined as having a closed canopy (75%-100% cover) allowing very little light to penetrate to the ground.2 By the end of the study in 2000, is it likely that this old field site (at 40°N) had reached the relative stability of a climax community? (the study began in 1950) A. No. Most forest communities take at least 100 years to reach 75% cover. B. No. According to the graphs, the old field will be at ~50% coverage after 50 years. C. Yes. Unless the area has been disturbed again, it should stay stable after 10% cover. D. Yes. At 40° latitude, over 50% of the old fields were above the stability line on the graph. O A B OC OD

The cutting and burning of tropical rain forests leads to which of the following? 1. Addition of CO2 to the atmosphere 2. Decreased removal of CO2 from the atmosphere 3. Reduced biodiversity 4. Climate change 1 only 2, 3, and 4 1, 2, and 3 1, 2, 3, and 4 1 and 2

To help preserve mountain biodiversity, it would be most helpful to reduce overgrazing reduce burning prevent oil production prohibit mineral extraction encourage use of off-road vehicles

What happens if there’s a natural disturbance (drought) affecting the balance of the food chain so that the Sun +E can supply only 4 energy units per plant? Compute for energy units following the table below.  Trophic Levels No. Individuals in Each Trophic Level No. of Units Received from Trophic Level Above No. Units Used / Individual  (Resp) No. Units Used in Trophic Level No. Units Remaining & Passed on to Next Trophic Level Mean No. Units Available per Individual in Trophic Level SUN +E = 4             1) Plants 30   2       2) Grasshopper 19   2       3) Frog 12   2       4) Snake 8   2       5) Owl 4   2