IB ESS/GURU
Changes occurring during a succession (refer to Fig. 14.4 on page 268) the size of organisms increases energy flow becomes more complex soil depth, humus, water-holding capacity, mineral content and cycling increase Biodiversity increases and then falls as the climax community is reached NPP and GPP rise and then fall Production: respiration ratio falls Species diversity in successions Early stages of succession: few species Species diversity increases with the succession Increase continues until a balance is reached between possibilities for new species to establish, existing species to expand their range and local extinction
TOPIC 3: Human Population, Carrying Capacity and Resource Use Population dynamics Exponential growth or geometric growth When the population is growing, and there are no limiting factors slowing the growth. Density-dependent limiting factors (biotic factors when effects depend on the population density) · Negative feedback mechanism- lead to stability of the population · Internal – factors act within species 1. Limited food supply lead to intraspecific competition 2. Lack of suitable territory 3. Survival of the fittest · External – factors act between different species (predation and disease) 1. Predation – pray animals increase, predators increase -> pray decreases and the predators decrease 2. Disease – at high populations spreads fast