Lines are drawn on a map and individuals occurring on those lines or belts are sampled

• transects
• quadrats
• point sampling
• mark and recapture

sampling units are placed randomly or in a grid pattern on the sampling area

• transects
• quadrats
• point sampling
• mark and recapture

Cone shaped filtering unit dragged through the water to collect tiny aquatic organisms

• Plankton net 
• Kick sampling
• Pitfall trap
• Beating tray

trees or branches are shaken and fallen insects, etc. are collected

• Plankton net 
• Kick sampling
• Pitfall trap
• Beating tray

the number of different species a community contains

• richness
• evenness
• density
• abundance

abundance of individuals within each of the species  in a community

• richness
• evenness
• density
• diversity

diversity is highest in the tropics and declines as we move from the equator toward the poles

• niche structure
• geographic location
• evenness
• density

how many potential niches occur, how they resemble or differ, how the various species interact

• niche structure
• geographic location
• evenness
• density

species help determine the types and numbers of other species in an area, helping to sustain the ecosystem

• keystone
• native
• indicator
• foundation

organisms that serve as early warnings of damage to a community or an ecosystem

• keystone
• native
• indicator
• foundation