ECOSYSTEM DYNAMICS Populations Symbiosis Succession

Populations Group of the same type of organism living in the same geographic area at a given time. Limiting Factors – Food Carrying Capacity - limits size Zero Growth (Steady State )

Measuring Populations Census – count all of the organisms in a population Direct count Sampling – count a small sample and use it to estimate the total population

Techniques for Sampling Quadrat Method Good for counting sessile things Construct a grid Count several random quadrats

Capture-Recapture Method Assumes population remains constant Capture, mark and release organisms Capture again, use formula:

Population Density Need: population size and area Ex. 40 oak trees in 10 acres

Population Distribution Clumped Uniform/Even Random

Symbiosis Species Interaction Predation Predator – consumes another individual, the prey Plants – adaptations to prevent predation (thorns)

Parasitism Parasite – feeds on host, harming but not killing it Ectoparasite – external (ticks) Endoparasite – internal (tapeworm)

Competition – species compete for same limited resource (water) Mutualism – both species benefit (clown fish, sea anemone ) Commensalism – one species benefits, the other unharmed (human, apple tree)

Succession The gradual change in a community over time. Primary community – development of a community where none existed before. (Bare rock succession) Secondary community – reclamation of a previously existing community (Farmer’s field succession) stableClimax community – long-term, generally stable ( Old forest community)