Name: forest tree density sampling method
Uploaded: 2023-04-30T06:36:33.000Z
Duration: 10 min 24 s
Channel: JoVE

K12 Standards

Alabama Course of Study Science

9-12

Environmental Science

Unity and Diversity

9-12.EVS.2.3.b

tree-survey-point-centered-quarter-sampling-method

Tree Survey: Point-Centered Quarter Sampling Method

<p class="jove_title">1. Tree Survey</p>
<ol>
	<li>Establish a 150 m transect in the forest.</li>
	<li>Place a stake every 50 m. Each stake (point) represents the center of four compass directions (N, E, W, S) that divide the sampling site into four quarters.</li>
	<li>In each quarter, the distance is measured from the stake to the nearest tree ≥ 40 cm, regardless of species. Only one large tree per quarter should be measured, so a total of 16 trees are recorded in the large tree category. Record the distance in cm for each.</li>
	<li>Collect a leaf sample from each tree. Be sure to note if the leaves are opposite, alternate, or wholred (<strong>Figure 1</strong>) before removing them. Place the sample on the herbarium paper, properly labeled with the tree number, and place in a plant press for later identification.</li>
	<li>Using a field measurement tape, measure the diameter of the tree at 4½ feet above the existing grade (dbh). Record the dbh. If using a dbh tape, read the diameter directly off the tape. If using a regular measuring tape, measure the circumference of the tree and then calculate the diameter using the formula C = π d.</li>
	<li>Repeat steps 1.3 – 1.5 for the nearest tree &lt; 40 cm and &gt; 2.5 cm in each quadrant. These trees are labeled the small tree category.</li>
	<li>Using the leaf samples, identify the species of each tree in the 16 large trees and the 16 small trees categories.</li>
</ol>
<p class="jove_content" fo:keep-together.within-page="always"><img alt="Leaf arrangement diagram: opposite, alternate, whorled patterns. Plant morphology study." src="/files/ftp_upload/10060/10060fig1.jpg" data-altupdatedat="1761830439000" data-alt="Figure 1"><br>
<strong>Figure 1.</strong> Examples of opposite, alternate, and whorled leaf arrangements.</p>
<p class="jove_title">2. Calculations</p>
<p class="jove_content">(Do separate analyses for large trees and small trees.)</p>
<ol>
	<li>Calculate the mean point-to-tree distance for the entire sample of large trees, regardless of species. Calculate the mean point-to-tree distance for the entire sample of small trees, regardless of species.</li>
	<li>Calculate the average density (the number of trees/hectare) for both the large trees and the small trees.<br>
	       <img alt="Average density formula; equation for calculating area density using tree distance measurement." src="/files/ftp_upload/10060/10060eq1.jpg" data-altupdatedat="1761830439000" data-alt="Equation 1"></li>
	<li>Determine the density <em>by species</em> for both the large trees and small trees. Then, count the number of individuals in the sample for each species and record (<strong>Table 1</strong>). The total number of individuals counted is 16.<br>
	         Relative Density = (number of individuals of a species/16) x 100%<br>
	And<br>
	         Density = (Relative Density/100) x Average Density</li>
	<li>Determine and record the basal area by species (<strong>Table 2</strong>).
	<ol>
		<li>Convert the diameter measures into areas for all trees sampled (a = π r<sup>2</sup>).</li>
		<li>Calculate the mean basal area for each species, i.e. take the average.</li>
		<li>For each species, calculate the Basal Area and Relative Basal Area.<br>
		        Basal Area = Density x Average Basal Area<br>
		And<br>
		        Relative Basal Area = (Basal Area / Total Basal Area) x 100<br>
		The Total Basal Area is the total basal area for all species (sum all BAs).</li>
	</ol>
	</li>
	<li>Determine and record frequency by species (<strong>Table 3</strong>).<br>
	        Frequency = (no. of points at which species occurs/total no. of points sampled)<br>
	And<br>
	        Relative Frequency = (Frequency/Total Frequency for all species) x 100
	<ol>
		<li>The frequency of each species is determined by comparing the number of points at which that species occurred out of the 4 points sampled. For example, if an American Elm is found at all 4 of the points, the frequency would be 4/4 = 1. If a Silver Maple is found at 2 of the 4 points, the frequency would be 2/4 = 0.5.</li>
	</ol>
	</li>
	<li> Calculate and record an Importance Value and Relative Importance Value by species (<strong>Table 4</strong>).<br>
	        Importance Value = Relative Density + Relative Frequency + Relative Basal Area<br>
	And<br>
	        Relative Importance Value = (Importance Value /Total Imp. Value for all species) x100</li>
	<li>Make a graph that depicts the importance value for each species on the y-axis and the species on the x-axis. Place them on the y-axis in order of Increasing Importance values. There should be one line for large trees and one line for small trees.</li>
</ol>
<table border="0">
	<tbody>
		<tr>
			<td colspan="4">
			<h3></h3>
			<h3>Large Trees</h3>
			</td>
		</tr>
		<tr>
			<td></td>
			<td># of individuals</td>
			<td>Relative Density (%)</td>
			<td>Density<br>
			(trees/hectare)</td>
		</tr>
		<tr>
			<td>Species 1 _______</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Species 2 _______</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Species 3 _______</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Species 4 _______</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Species 5 _______</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Species 6 _______</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td colspan="4">
			<h3></h3>
			<h3>Small Trees</h3>
			</td>
		</tr>
		<tr>
			<td></td>
			<td># of individuals</td>
			<td>Relative Density (%)</td>
			<td>Density<br>
			(trees/hectare)</td>
		</tr>
		<tr>
			<td>Species 1 _______</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Species 2 _______</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Species 3 _______</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Species 4 _______</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Species 5 _______</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Species 6 _______</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>
<p></p>
<p><strong>Table 1.</strong> A table to fill out information regarding the density of large and small trees.</p>
<table border="1">
	<tbody>
		<tr>
			<td colspan="4">
			<h3></h3>
			<h3>Large Trees</h3>
			</td>
		</tr>
		<tr>
			<td></td>
			<td>Average Basal Area<br>
			 (m<sup>2</sup>)</td>
			<td>Basal Area<br>
			(m<sup>2</sup>)</td>
			<td>Relative Basal Area</td>
		</tr>
		<tr>
			<td>Species 1 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Species 2 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Species 3 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Species 4 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Species 5 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Species 6 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>TOTAL</td>
			<td></td>
			<td>Total Basal Area =</td>
			<td></td>
		</tr>
		<tr>
			<td colspan="4">
			<h3></h3>
			<h3>Small Trees</h3>
			</td>
		</tr>
		<tr>
			<td></td>
			<td>Average Basal Area<br>
			 (m<sup>2</sup>)</td>
			<td>Basal Area<br>
			(m<sup>2</sup>)</td>
			<td>Relative Basal Area</td>
		</tr>
		<tr>
			<td>Species 1 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Species 2 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Species 3 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Species 4 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Species 5 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Species 6 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>TOTAL</td>
			<td></td>
			<td>Total Basal Area =</td>
			<td></td>
		</tr>
	</tbody>
</table>
<p><strong>Table 2.</strong> A table to fill out information regarding the basal area of large and small trees.</p>
<table border="1">
	<tbody>
		<tr>
			<td colspan="4">
			<h3></h3>
			<h3>Large Trees</h3>
			</td>
		</tr>
		<tr>
			<td></td>
			<td># of points</td>
			<td>Frequency</td>
			<td>Relative Frequency</td>
		</tr>
		<tr>
			<td>Species 1 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Species 2 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Species 3 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Species 4 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Species 5 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Species 6 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>TOTAL</td>
			<td></td>
			<td>Total Frequency =</td>
			<td></td>
		</tr>
		<tr>
			<td colspan="4">
			<h3></h3>
			<h3>Small Trees</h3>
			</td>
		</tr>
		<tr>
			<td></td>
			<td># of points</td>
			<td>Frequency</td>
			<td>Relative Frequency</td>
		</tr>
		<tr>
			<td>Species 1 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Species 2 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Species 3 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Species 4 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Species 5 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Species 6 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>TOTAL</td>
			<td></td>
			<td>Total Frequency =</td>
			<td></td>
		</tr>
	</tbody>
</table>
<p><strong>Table 3.</strong> A table to fill out information regarding the frequency of large and small trees.</p>
<table border="1">
	<tbody>
		<tr>
			<td colspan="6">
			<h3></h3>
			<h3>Large Trees</h3>
			</td>
		</tr>
		<tr>
			<td></td>
			<td>Relative<br>
			Density</td>
			<td>Relative<br>
			Frequency</td>
			<td>Relative<br>
			Basal<br>
			Area</td>
			<td>Importance<br>
			Value</td>
			<td>Relative<br>
			Importance<br>
			Value</td>
		</tr>
		<tr>
			<td>Species 1 _______________</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Species 2 _______________</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Species 3 _______________</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Species 4 _______________</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Species 5 _______________</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Species 6 _______________</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td>Total IV =</td>
			<td></td>
		</tr>
		<tr>
			<td colspan="6">
			<h3></h3>
			<h3>Small Trees</h3>
			</td>
		</tr>
		<tr>
			<td></td>
			<td>Relative<br>
			Density</td>
			<td>Relative<br>
			Frequency</td>
			<td>Relative<br>
			Basal<br>
			Area</td>
			<td>Importance<br>
			Value</td>
			<td>Relative<br>
			Importance<br>
			Value</td>
		</tr>
		<tr>
			<td>Species 1 _______________</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Species 2 _______________</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Species 3 _______________</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Species 4 _______________</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Species 5 _______________</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Species 6 _______________</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td>Total IV =</td>
			<td></td>
		</tr>
	</tbody>
</table>
<p><strong>Table 4.</strong> A table to fill out information regarding the Importance Value and Relative Importance Value of large and small trees.</p>


<p class="jove_content">Tree surveys are an important technique for both private and public stakeholders. They can provide helpful information to allow land managers to make informed decisions. A community may want to do a tree inventory to determine if there is a need for a forestry program. For example, the survey may reveal many dead or diseased trees (<strong>Figure 3</strong>) and indicate the need for more plantings. The survey may also help the community set up a maintenance schedule to prevent damage from hazardous trees. Lastly, the su...

tree survey: point-centered quarter sampling method

<p class='jove_content'>A number of methods are available for sampling forest communities. Point-centered quarter is one such method. It is used to gather information on the density, frequency, and coverage of tree species found in a forest. This information provides the ability to estimate the number of individual trees encountered, how often a certain tree occurs, how common the tree is compared to other trees, and the size of the tree. Compared to the standard plot analysis, the point-centered quarter method is more efficient, which is a major advantage. In a fixed-area plot sampling, a small portion of the total area of the forest is examined. In this small subsample, the density is determined directly by counting and identifying each tree. The ratio between size of the subplot and the overall forest size is used to determine the density for the entire forest.</p>

<p class="jove_content">The point-centered quarter tree survey method produces three quantitative measures: the relative density, the relative frequency, and the relative basal area. These three values are added together to give the Importance Value of that species. This is then converted to a relative importance value (<strong>Table 5</strong>).</p>
<p class="jove_content">The importance value of a species can reach a maximum of 300 in a survey that only finds one species present. A high importance value does not necessarily mean that the spec...

A number of methods are available for sampling forest communities. Point-centered quarter is one such method. It is used to gather information on the ...

<p>Tree surveys are important to evaluate biodiversity in forests and elucidate the structure and health of woodland areas. The point-centered quarter sampling method is a common technique used to quantify woodland composition.</p><p>Woodlands are an important natural resource, and help maintain the environment, while having an impact on the health and quality of life of human populations. A good understanding of the composition of forests is essential to maintaining this resource. If a forest is very diverse, it can minimize the impact from species-specific pests or disease. If invasive trees dominate the understory, this may indicate future displacement of native trees.</p><p>Point-centered quarter sampling is one commonly used method in forest communities. It is used to gather information on the density, frequency, and coverage of tree species found in a forest. Data collected via this method provide the ability to estimate how often a tree species occurs, how common species are relative to others, and the sizes of trees, which can give an estimation of age of the tree, and the space they occupy in the ecosystem.</p><p>The point-centered method has advantages over other tree survey types. It is more efficient than standard plot analysis because it requires only a small sampling across the woodland, as opposed to surveying all present trees. Though less labor intensive, it has been shown to provide comparable results.</p><p>This video will illustrate how to carry out a point-centered quarter sample, how to calculate related tree data, and how to analyze the findings of a point-centered quarter tree survey.</p><p>The point-centered quarter tree survey method produces three major quantitative measures for a specific tree species: Relative Density, Relative Frequency, and Relative Basal Area. These three values are then added together to give an "Importance Value" of that species, which can be converted into a "Relative Importance Value." This value gives a numerical quantification of the prevalence and abundance of a tree species within the forest.</p><p>Point-centered quarter method uses a tree measurement called Diameter at Breast Height, or DBH. This is measured at 4.5 ft above existing grade. After a survey location has been selected a transect is established, a point in the forest along that transect is chosen, and the area around it separated into four quarters. In each quarter, the nearest tree with a DBH of greater than 40 cm is identified. This collection is considered the large tree sample.</p><p>Next, in each quarter, the nearest tree with a DBH of greater than 2.5 cm, but below 40 cm is identified. These are labeled the small tree sample. Identifying a large tree and small tree in each quadrant allows comparison of the high, canopy forming overstory vegetation to the lower level understory growth.</p><p>Using these simple measurements, Basal Area and Importance Value of each tree species can be calculated. The Basal Area is the cross-sectional area of a single tree at DBH. Calculating the total basal area of all trees of a species is a more accurate way to understand species density, and is used instead of number of trees per site to take into account the size of the trees.</p><p>The Importance Value of each species is calculated to estimate the relative dominance of a particular species in a forest community. It takes into account how commonly a species occurs across the forest, total number of individuals of the species, and the total amount of forest area that the species occupies.</p><p>Now that we are familiar with the importance of tree surveys and the principles of point-centered quarter surveys, let's take a look at how these are carried out in the field.</p><p>Once a woodland site has been identified, establish a 150 m transect in the forest. This can begin anywhere in the woodland, but should preferably be away from the forest edge to minimize border effects from external sources, such as roads.</p><p>Place a stake every 50 m along the transect. Each stake represents the center of four compass directions that divide the sampling site into four quarters. These can be numbered by location from one end if desired.</p><p>In each quarter, the distance is measured from the stake to the nearest tree, of any species, larger than 40 cm in diameter. Only one large tree per quarter should be measured, so a total of 16 trees are recorded in the large tree category. Record the distance to the stake in centimeters for each.</p><p>At each measured tree, note if the leaves are arranged in an alternate, whorled, or opposite arrangement. Next, collect a leaf sample for each of the measured trees.</p><p>Place the leaf samples on herbarium paper and label according to collection site, then place in a plant press for later identification.</p><p>For each sample tree, using field measurement tape, record the DBH. If using specific DBH tape, read the diameter directly. With regular measuring tape, measure the tree circumference, then calculate the diameter using the formula.</p><p>Next, repeat these measurements for each quadrant, at each segment of the transect for the nearest tree less than 40 cm and greater than 2.5 cm in diameter. Record these in a separate category, labeled as small trees.</p><p>Back at the laboratory, calculate the mean point-to-tree distance, density, and basal area for each species. This information can then be used to generate the Importance Value. First, using a tree identification guide or ID key, identify each of the trees measured in both the large and small tree categories.</p><p>Calculate the mean point-to-tree distance for the entire sample of large and small trees. This is the mean value for the distance of the tree group to the transect point.</p><p>Next, calculate the average density, or number of trees per hectare for both the large tree and small tree groups using the equation shown. Record the number of individuals of each tree species per group, then determine density by species for both the large tree and small tree group.</p><p>Convert the diameter measurements into areas for all trees sampled. Calculate the mean basal area for each species by calculating the average. The basal area of a species is the average basal area of that species times its density. Next, for each species, calculate the Relative Basal Area.</p><p>Determine the frequency at which each species occurs in each group. This is determined by comparing the number of points at which that species occurred out of the 4 points sampled. For example, if an American elm is found at all four points of a quadrant, frequency would equal 1. If a Silver Maple is found at 2 of 4 points, frequency would be equal to 0.5 Now, determine the relative frequency of each species, for each group.</p><p>The Importance Value of a species can now be calculated. Add the relative density to relative frequency plus relative basal area. Finally, determine the Relative Importance Value for each species.</p><p>To summarize, input these data into a graph that depicts the Importance Value for each species on the Y-axis, arranged in order of increasing importance, and the species name on the X-axis. The data should be presented as one bar for large trees and one bar for small trees.</p><p>The importance value of a species can reach a maximum of 300 in a survey where only one tree species is observed. High Importance Value does not necessarily mean a species is important to the health of the forest. Instead, it is merely an indication that the species is currently dominant in the forest structure.</p><p>Tree surveys are used to inform scientists or land managers on a variety of important topics. The point-centered quarter method may be applied in a variety of information gathering scenarios.</p><p>A community may benefit from a tree inventory to determine a need for a forestry program if there is a high frequency of dead or diseased trees in local woodland. Such trees can prove a health risk from falling branches, or an infection risk to others. Finding many dead or diseased trees in a forest would raise concerns for environmental scientists, and may be early indicators of poor environmental conditions including acid rain or ozone pollution.</p><p>Knowing species diversity in a forest can help land managers develop planting strategies. They may be informed to set guidelines to limit or eliminate planting of common trees while adding in new or uncommon beneficial species to maintain diversity. Data from a tree survey may also allow managers to calculate the worth of the services specific tree species provide, such as air pollution control or carbon capture and storage, and tailor planting strategies based upon these data.</p><p>You've just watched JoVE's introduction to Tree Surveying using the point-centered quarter method. You should now understand the importance of tree surveys, how to carry out a point-centered quarter survey, and how to calculate forest structure based on your survey measurements. Thanks for watching!</p>

Education

JoVE Science Education

Environmental Sciences

forest tree density sampling method

<p class="jove_content">Forest tree density sampling can be done with the point-centered quarter method. This field method helps measure the density, frequency, and coverage of tree species in a forest. It also helps estimate how many individual trees are present, how often a tree species appears, how common it is compared with other trees, and the size of the trees.</p>

<p class="jove_content">The point-centered quarter method is useful because it is more efficient than standard plot analysis. In fixed-area plot sampling, only a small part of the forest is examined. Trees in that subplot are counted and identified directly to determine density.</p>

<p class="jove_content">The density from the small sample is then used to estimate the density for the whole forest. The ratio between the size of the subplot and the total forest area supports that estimate. This makes point-centered quarter sampling a practical way to study forest communities.</p>

Forest Tree Density Sampling Method

tree identification: how to use a dichotomous key

tree-identification-how-to-use-a-dichotomous-key

Leaf Traits and Tree ID With a Key

Leaf traits can help students identify trees with a dichotomous key. A dichotomous key is a nature ID tool that works by choosing between two characteristics at each step. The word dichotomous comes from two Greek words that mean "to divide into two...

Forest tree density sampling can be done with the point-centered quarter method. This field method helps measure the density, frequency, and coverage of tree species in a forest. It also helps estimate how many individual trees are present, how often a tree species appears, how common it is compared with other trees, and the size of the trees.<br /><br />The point-centered quarter method is useful because it is more efficient than standard plot analysis. In fixed-area plot sampling, only a small part of...

using gis to investigate urban forestry

GIS Mapping of Urban Trees and Parks

GIS helps map urban forests and the many trees found in cities. Urban forests include urban parks, street trees, landscaped boulevards, public gardens, river and coastal promenades, greenways, river corridors, wetlands, nature preserves, natural areas, shelterbelts of trees, and even working trees at industrial brownfield sites. These spaces are more than decoration. They are part of city infrastructure and support human life in ways similar to food, housing, and other public utilities.<br /><br />Urban...

proton exchange membrane fuel cells

Hydrogen Power from PEM Fuel Cells

Proton exchange membrane fuel cells use hydrogen gas to make electric current. They are part of the search for cleaner energy sources that can help replace non-renewable fuels used for electricity, transportation, industry, and homes. The United States now uses about 97.5 quadrillion BTUs of energy each year, and about 90% still comes from non-renewable sources.<br /><br />Hydrogen is one possible renewable energy carrier. It is abundant in the universe, but on Earth it is found in compounds such as...

biofuels: producing ethanol from cellulosic material

biofuels-producing-ethanol-from-cellulosic-material

Ethanol Production from Plant Waste

Ethanol can be produced from plant waste such as corn stalks, leaves, and grasses. In this lab, cellulosic material is used as the feedstock, which means it is the starting plant material for the reaction. The process shows how biomass can be turned into a fuel product.<br /><br />The material is first pretreated by grinding and heating it. It is then digested with enzymes, which break the material down further. Next, yeast ferments the sample and ethanol forms during the reaction.<br /><br />Ethanol production is...

testing for genetically modified foods

Detecting GMO DNA in Food Samples

Food DNA can be tested for genetically modified material by using PCR and gel electrophoresis. This experiment shows how food DNA is identified so students can better understand the science behind GMOs and the concerns linked to health and environmental safety.<br /><br />Polymerase chain reaction, or PCR, is used to amplify the DNA from food samples. Amplifying the DNA makes it possible to test for the presence of genetically modified DNA. The method gives a clear way to compare test foods with known...

turbidity and total solids in surface water

turbidity-and-total-solids-in-surface-water

Measuring Water Clarity with Secchi Disks

Turbidity and total solids are two ways to measure water clarity in surface waters. Turbidity is an indirect measure. It shows how much light can pass through the water. Total solids are measured directly by weight and show the amount of solid particles suspended in the water.<br /><br />High turbidity and high total solids can come from soil erosion, waste discharge, runoff, or changes in ecological communities. Algal growth and the abundance of benthic organisms can also disturb sediment and mix it...

dissolved oxygen in surface water

How Low Oxygen Creates Dead Zones

Dissolved oxygen in surface water helps support life in lakes, rivers, and oceans. Fish, such as bluegill and bass, need it to survive. Decomposer species also depend on it to recycle biogeochemical materials in the ecosystem.<br /><br />When dissolved oxygen drops below normal levels, water quality declines and organisms begin to die. Low oxygen can happen during eutrophication, when excess nutrients trigger a fast algal bloom. The bloom forms dense mats at the surface and blocks two key oxygen sources:...

nutrients in aquatic ecosystems

How Nutrients Drive Algal Blooms

Nitrogen and phosphorus are important nutrients in aquatic ecosystems. Water quality tests often monitor both because too much of either can create serious water quality problems.<br /><br />Nitrogen in water is usually measured as nitrate, written as NO3-. Nitrate dissolves in water and is easily taken up by photosynthesizers such as algae. Phosphorus is usually measured as phosphate, written as PO43-. Phosphate can be found dissolved in water, and it also binds strongly to sediment particles.<br /><br />When...

measuring tropospheric ozone

Tropospheric Ozone in Air and Smog

Tropospheric ozone is an air pollutant found in the lower atmosphere. It is a form of elemental oxygen, O3, made of three oxygen atoms in a highly reactive structure. In the troposphere, ozone contributes to photochemical smog and can harm people, plants, and materials.<br /><br />Ozone also exists in the stratosphere, about 10 to 50 km above Earth’s surface. There, it forms the ozone layer and helps block harmful UV rays from reaching the ground. Tropospheric ozone is different because it occurs near...

determination of no<sub>x</sub> in automobile exhaust using uv-vis spectroscopy

determination-of-nox-in-automobile-exhaust-using-uv-vis-spectroscopy

How Car Exhaust NOx Drives Smog Formation

Car exhaust releases nitrogen oxides, or NOx, that help drive smog formation in the lower atmosphere. In the troposphere, sunlight splits nitrogen dioxide (NO2) into nitric oxide (NO) and oxygen atoms. Those oxygen atoms then combine with O2 to make ozone (O3). Ozone can also react with NO to reform NO2 and O2, so this cycle does not create a net gain of ozone on its own.<br /><br />Problems begin when fossil fuel combustion adds extra NO, NO2, and volatile organic compounds (VOCs) to the air. Motor...

lead analysis of soil using atomic absorption spectroscopy

lead-analysis-of-soil-using-atomic-absorption-spectroscopy

Testing Soil for Lead Contamination

Lead contamination in soil can be measured with atomic absorption spectroscopy. Lead is a naturally occurring element in soil, usually at 10 to 50 ppm. But soil near old paint, gasoline use, or industrial pollution can contain much higher levels. In some urban areas, lead can reach 10,000 ppm.<br /><br />Lead stays in soil because it does not biodegrade. That makes it a long-term hazard. Children are at particular risk from lead exposure. Millions of children in the U.S. may contact soil that contains...

carbon and nitrogen analysis of environmental samples

carbon-and-nitrogen-analysis-of-environmental-samples

Measuring Carbon and Nitrogen in Soil

Carbon and nitrogen in soil can be measured by elemental analysis. Environmental samples such as soils are often studied for these two ecologically important elements. Scientists use these results to understand the elemental makeup of a material.<br /><br />This method uses flash combustion to analyze the sample. The sample is oxidized with a catalyst in a high-temperature chamber. The combustion products are then reduced to nitrogen gas (N2) and carbon dioxide (CO2). A thermal conductivity detector...

soil nutrient analysis: nitrogen, phosphorus, and potassium

soil-nutrient-analysis-nitrogen-phosphorus-and-potassium

Measuring Soil Fertility with NPK Tests

Soil fertility can be measured by testing the macronutrients nitrogen, phosphorus, and potassium. These three nutrients are major parts of soil fertilizer, and their levels help show how well soil can support plant growth.<br /><br />The experiment uses chemical extraction to pull each nutrient out of the soil and into a solution. Color-based reagents are then added to the extracted samples. The nutrients are analyzed by color and turbidity, which is the cloudiness of a solution, to estimate how much of...

analysis of earthworm populations in soil

analysis-of-earthworm-populations-in-soil

Mustard Soil Sampling for Earthworms

Earthworm populations can be sampled from soil with mustard. The mustard draws Lumbricus terrestris earthworms up from deeper soil layers. This method lets scientists collect data without disturbing the landscape or using toxic chemicals.<br /><br />After sampling, the earthworms are counted. The counts can then be used for data analysis and statistical testing. A bar graph and a student’s t-test help compare the results.<br /><br />Monitoring earthworm populations is important in environmental science. Many...

environmental science

This collection utilizes an interdisciplinary approach to explore and evaluate environmental systems with topics ranging from soil and water contaminants, invasive species, alternative energy and forestry. 

Learn how point-centered quarter sampling estimates tree density, frequency, and coverage in forest communities, and why it is more efficient than plot sampling.

Forest Tree Density Sampling Method | JoVE K12

Next Generation Science Standards

High School

Life Science

ecosystems-interactions-energy-and-dynamics

Ecosystems: Interactions, Energy, and Dynamics

HS-LS2-1

HS-LS2-2

Earth and Space Science

Earth and Human Activity

HS-ESS3-1

HS-ESS3-4

south-carolina-college-and-career-ready-science-standards

South Carolina College and Career Ready Science Standards

Biology

Biological Evolution: Unity and Diversity

B-LS4-6.

new-york-state-science-learning-standards

New York State Science Learning Standards

engineering-technology-and-applications-of-science

Engineering, Technology, and Applications of Science

Engineering Design

HS-ETS1-2.

HS-ETS1-3.

HS-ETS1-4.

interdependent-relationships-in-ecosystems

Interdependent Relationships in Ecosystems

HS-LS2-2.

Earth and Space Sciences

Human Sustainability

HS-ESS3-1.

HS-ESS3-3.

HS-ESS3-4.

HS-ESS3-6.

Georgia Standards of Excellence

SEV4.

SEV4.a

Kimberly Frye

Overview

Principles of Tree Surveying by the Point-Centered Quarter Method

Tree Survey

Data Analysis and Results

Applications

Summary

What are Populations and Communities?

Populations are groups of individuals of the same species that inhabit a shared environment. Communities include multiple co-existing, interacting ...

Distribution and Dispersion

Ecology is the study of how organisms interact with their environment and with one another. An important aspect of ecology is understanding where species ...

Life Histories

Constrained by limited energy and resources, organisms must compromise between offspring quantity and parental investment. This trade-off is represented ...

Ecological Niches

All organisms have a position within an ecosystem. The complete set of living and nonliving factors&#x2014;including food resources, climate, and ...

Ecological Succession

Ecological succession is influenced by the processes of facilitation, inhibition, and toleration. Facilitation occurs when early successional species ...

What is an Ecosystem?

Overview

An ecosystem is the interaction between all abiotic and biotic factors in an environment and can be classified as terrestrial or aquatic. ...

3. Construct an explanation of how biotic and abiotic factors affect biodiversity and populations in ecosystems. Examples: Explain how factors such as biomass, reproductive strategies, succession, climate, and geography affect an organism's chances of surviving and reproducing through successive generations.

9-12.EVS.2.3

Keystone Species

Measures of species biodiversity, such as richness (i.e., the number of species present) and evenness (i.e., their relative abundance), describe an ...

What is Biodiversity?

Biodiversity describes the variety of living things at multiple organizational levels: genetic, species and ecosystem diversity. Species diversity ...

Threats to Biodiversity

There have been five major extinction events throughout geological history, resulting in the elimination of biodiversity, followed by a rebound of species ...

Analysis of Earthworm Populations in Soil

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
Using mustard, Lumbricus terrestris earthworm populations can be sampled ...

water-quality-analysis-via-indicator-organisms

Water Quality Analysis via Indicator Organisms

Source: Laboratories of Dr. Ian Pepper and Dr. Charles Gerba -The University of Arizona
Demonstrating Author: Luisa Ikner
Water quality analysis monitors ...

What is Conservation Biology?

Conservation biology is a scientific field that focuses on the preservation of biodiversity in order to protect ecosystems while meeting the needs of the ...

Measuring Biodiversity

Diverse ecosystems are important for the health of the planet and our survival as humans; it is therefore incredibly important for us to understand and ...

Community Diversity

Populations do not live in isolation; thus, every population interacts with others in certain ways. These interactions give rise to a network of ...

a. Support a claim that biodiversity is a natural resource which fosters ecosystem resilience, including the role of keystone, invasive, native, endemic, and indicator species.

9-12.EVS.2.3.a

gis-software-hardware-and-sources-of-gis-data

GIS Software, Hardware, and Sources of GIS Data

A Geographic Information System (GIS) combines specialized software and hardware to effectively manage, analyze, and present spatial and related data. GIS ...

Manipulation and Analysis

GIS manipulation and analysis functions are vital for decision-making and planning. These activities range from data retrieval tasks, such as selecting ...

Using GIS to Investigate Urban Forestry

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
Urban forests broadly include urban parks, street trees, landscaped ...

using-topographic-maps-to-generate-topographic-profiles

Using Topographic Maps to Generate Topographic Profiles

Source: Laboratory of Alan Lester - University of Colorado Boulder
Topographic maps are &#34;plan-view&#34; representations of Earth&#39;s ...

Tree Identification: How To Use a Dichotomous Key

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
A dichotomous key is a tool that identifies items in nature, such as ...

Introduction to Microbial Ecology

Microbial ecology examines the complex web of interactions and diversity among microorganisms within various ecosystems. This field seeks to understand ...

Species Distribution and Biogeography

Simulating Colonization and Extinction on Islands
ExpandForm groups of three. One member of the group will simulate colonization by throwing balls into ...

Freshwater Microbial Ecology

Freshwater systems such as streams, rivers, and lakes exhibit distinct physical and biological characteristics that influence their microbial communities. ...

Soil Microbial Ecology

Soil microbial ecology is defined by highly diverse, spatially structured communities that drive nutrient cycling, organic matter turnover, and overall ...

b. Analyze and interpret data collected through geographic research and field investigations to describe Alabama's biodiversity by region. Examples: Use relief, topographic, and physiographic maps or information on rivers, forests, and watersheds to investigate species distributions and diversity.

Forest Tree Density Sampling Method

Description

Transcript

Tags

More videos by Standards