Ecology Lab: An Introduction to Biodiversity Sampling

Overview 

Ecological communities are built on the interactions between the organisms and the physical environment that surrounds them. The living organisms, or biotic factors, interact as predators, prey and competitors for resources. The physical environment, or abiotic factors, such as water, sunlight, climate, temperature, soil and oxygen are part of what determine how many living creatures can be supported in the ecosystem. Plants are important in ecological communities. Not only do plants represent a large source of primary production, they also determine the potential for wildlife to exist in an area. Disturbance of vegetation can have cascading effects through an ecosystem and changing the diversity and abundance of plants will affect the other living communities, such as animals, insects, fungi, and soil microbes (Schulz et al 2009). In particular, the more sunlight and water that is available in an area the greater the diversity of plants and animals can live in that area. For example, picture the difference between a desert and a tropical rainforest. The desert gets little water so not very many plants can grow there, which leads to few animals living there as well. In contrast, a tropical rainforest gets plenty of both sunlight and rain and hosts a wide variety of both plants and animals.
The question of how many species exists in an environment is central to understanding why it is important to promote and preserve species diversity. Promoting a singular species could leave an ecosystem at risk of failure when environmental conditions change (AMNH 2015). Biodiversity is a measure of the number and variety of different plant and animal species that live in an ecosystem. A high biodiversity can be correlated with a more stable ecosystem because there are a wider variety of resources for foraging, nesting, and seeking shelter. There is redundancy in resources as organisms can meet their needs in a variety of ways.
When studying an ecosystem, ecologists first try to survey what populations of organisms naturally live there, then measure how many of each organism lives there. This is referred to as the population density of that species. Ecologists measure population density by counting the number of each species in a sample area called a quadrat. If they count the population size in a number of quadrats chosen at random around the ecosystem, scientists can estimate how many of each species live in the whole ecosystem. The carrying capacity is how many individuals of a species that can survive in an area given the resources (food, water, and nesting sites) available (Folgia 2008). Quadrat sampling can either be random or systematic depending on the nature of your research question. In random quadrat sampling, the habitat is broken down into a grid-like system of squares and each square is assigned a number. Then a random number generator is used to select which square you will be observing. An example of systematic quadrat sampling is transect sampling, which simply means moving along a predetermined path, taking samples at predetermined regular intervals, such as from the edge of the habitat into the center. Sampling is done at regular distances to compare the biodiversity of the edge of the habitat with the interior.
In this lab you will be performing quadrat sampling to gauge the biodiversity of a habitat. You will get to choose where this habitat is but remember that you MUST follow social distancing protocols while completing this lab. If you can, complete this lab at your local park, in your yard/courtyard, or in a green area that’s legally accessible. If you can’t get outside, email me and we’ll figure out an alternative.
Be sure to read this whole lab before you head out so you know exactly what is expected of you, and take photos of what you’re doing as you go through this lab. You’ll be asked to attach your photos to the conclusion before you submit this assignment.

Research question 

How does plant diversity change when moving from to edge of the habitat to the center?

Instructions 

First, watch this video showing you how to conduct a quadrat sample:
https://www.youtube.com/watch?v=RhMOCxXcDrQ
Next, find something around your house that you can make a 1 meter x 1 meter square with. Here’s what I found at my house, but you could also use rope, string, random branches, yardsticks, or whatever else you have lying around. Feel free to get creative!