Science Courses / Course / Chapter

Bottom-Up & Top-Down Models of Community Organization

Lesson Transcript
Instructor: Artem Cheprasov

Artem has a doctor of veterinary medicine degree.

Government structures are typically considered either top-down or bottom-up organizations. Become familiar with these community organization models using an analogy of biomass, defined as the total mass of living matter found within an ecosystem. Updated: 11/16/2021

Community Organization

In governments, communities are generally organized in a top-down or bottom-up fashion. Either you're a proponent of the 'trickle-down effect' or of grassroots organization. Similarly, in nature, communities may be organized in a bottom-up or a top-down model. What do these models represent? Well, for one thing, it has nothing to do with voting or your political beliefs, since these are models of a more natural rather than human understanding.

An error occurred trying to load this video.

Try refreshing the page, or contact customer support.

Coming up next: What is an Ecological Imbalance? - Definition & Explanation

You're on a roll. Keep up the good work!

Take Quiz Watch Next Lesson
Your next lesson will play in 10 seconds
  • 00:00 Community Organization
  • 00:27 Bottom-Up
  • 2:24 Top-Down
  • 3:22 Lesson Summary
Save Save Save

Want to watch this again later?

Log in or sign up to add this lesson to a Custom Course.

Log in or Sign up

Speed Speed


Let me pose a little simple scenario for you so you can begin mulling over the two models, the first one being the bottom-up model. Let's say there is some grassland and some deer. The grass, G, provides food for the deer, D. In the bottom-up model, we can say that the flow of influence on community organization goes in one direction, G to D, meaning it flows from a lower trophic level (grass) to a higher one (deer). From the bottom to the top, bottom-up. What this means is that if there is more grass, then deer will increase in number, or biomass, the total mass of living matter in a certain region. However, because the flow of G to D is unidirectional, the abundance of deer will not change the abundance of grass in such a model.

Okay, that was a simple example. Let's solidify our understanding of the bottom-up model with a more complex example. Let's say the soil contains nutrients, N, that helps the grass, G, grow. This, in turn, controls the number of deer, D and this, in turn, controls the number of predators, wolves, W. In the bottom-up model, our flow of influence is thus N to G to D to W. This means that if we want to alter this bottom-up community structure, we have to change the biomass at lower trophic levels in order to affect the higher trophic levels. If we increase the abundance of N, then G should increase and, theoretically, so should D and then W. However, if you decrease W, this should not effect lower trophic levels.

To unlock this lesson you must be a Member.
Create your account

Register to view this lesson

Are you a student or a teacher?

Unlock Your Education

See for yourself why 30 million people use

Become a member and start learning now.
Become a Member  Back

Resources created by teachers for teachers

Over 30,000 video lessons & teaching resources‐all in one place.
Video lessons
Quizzes & Worksheets
Classroom Integration
Lesson Plans

I would definitely recommend to my colleagues. It’s like a teacher waved a magic wand and did the work for me. I feel like it’s a lifeline.

Jennifer B.
Jennifer B.
Create an account to start this course today
Used by over 30 million students worldwide
Create an account