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. 树木调查</p>
<ol>
	<li>在森林中建立一条150米的样线。</li>
	<li>每隔50米放置一根标桩。每根标桩（点）代表四个罗盘方向（北、东、西、南）的中心，将采样点划分为四个象限。</li>
	<li>在每个象限中，测量从标桩到最近的一棵胸径≥40 cm的树木的距离，不考虑树种。每个象限仅测量一棵大树，因此共记录16棵大树。分别记录每棵树的距离（单位：cm）。</li>
	<li>从每棵树上采集一片叶子样本。在取下叶片前，务必记录叶片为对生、互生或簇生（<strong>图1</strong>）。将样本放置在标本纸上，并正确标注树木编号，随后放入植物压片夹中，以备后续鉴定。</li>
	<li>使用野外测量卷尺，在距地面4½英尺处测量树木的直径（胸径，dbh）。记录胸径数值。若使用胸径卷尺，可直接读取直径值；若使用普通卷尺，则测量树干周长，并利用公式 C = π d 计算直径。</li>
	<li>在每个象限中，对最近的一棵胸径&lt;40 cm且&gt;2.5 cm的树木，重复步骤1.3–1.5。这类树木归为小树类别。</li>
	<li>利用叶片样本，鉴定16棵大树和16棵小树各自所属的树种。</li>
</ol>
<p class="jove_content" fo:keep-together.within-page="always"><img alt="叶序图示：对生、互生、轮生模式。植物形态学研究。" src="/files/ftp_upload/10060/10060fig1.jpg" data-altupdatedat="1761830439000" data-alt="图1"><br>
<strong>图1.</strong> 对生、互生和轮生叶序的示例。</p>
<p class="jove_title">2. 计算</p>
<p class="jove_content">（对大树和小树分别进行分析。）</p>
<ol>
	<li>计算所有大径级树木样本的平均点-树距离，不考虑物种差异。计算所有小径级树木样本的平均点-树距离，不考虑物种差异。</li>
	<li>分别计算大树和小树的平均密度（树木数量/公顷）。<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>测定密度 <em>按物种</em> 对于大树和小树均需进行。然后，统计每个物种在样本中的个体数量并记录（<strong>表1</strong>）。统计的个体总数为16。<br>
	         相对密度 = （某一物种的个体数量 / 16）× 100%<br>
	并且<br>
	         密度 = (相对密度/100) × 平均密度</li>
	<li>按物种测定并记录基部面积（<strong>表 2</strong>).
	<ol>
		<li>将所有采样树木的直径测量值转换为面积（a = π r²）<sup>2</sup>).</li>
		<li>计算每个物种的平均基部面积，即取平均值。</li>
		<li>针对每个物种，计算其基部面积和相对基部面积。<br>
		        基部面积 = 密度 × 平均基部面积<br>
		以及<br>
		        相对基部面积 = (基部面积 / 总基部面积) × 100<br>
		总基部面积是所有物种的基部面积之和（将所有BA相加）。</li>
	</ol>
	</li>
	<li>按物种确定并记录频率（<strong>表3</strong>).<br>
	        频率 = （物种出现的样点数 / 采样的总样点数）<br>
	并且<br>
	        相对频率 = （频率 / 所有物种的总频率）× 100
	<ol>
		<li>通过比较每个物种在4个取样点中出现的点数来确定其频度。例如，若美国榆树在4个点位中均出现，则频度为4/4 = 1；若银枫在4个点位中的2个出现，则频度为2/4 = 0.5。</li>
	</ol>
	</li>
	<li> 按物种计算并记录重要值和相对重要值<strong>表4</strong>).<br>
	        重要性值 = 相对密度 + 相对频度 + 相对基面积<br>
	并且<br>
	        相对重要值 = （重要值 / 所有物种的重要值总和）× 100</li>
	<li>绘制一幅图表，纵轴表示每个物种的重要性值，横轴表示物种。按照重要性值递增的顺序在纵轴上排列物种。图表中应包含两条线，分别代表大树和小树。</li>
</ol>
<table border="0">
	<tbody>
		<tr>
			<td colspan="4">
			<h3></h3>
			<h3>大型树木</h3>
			</td>
		</tr>
		<tr>
			<td></td>
			<td>个体数量</td>
			<td>相对密度（%）</td>
			<td>密度<br>
			(株/公顷)</td>
		</tr>
		<tr>
			<td>物种 1 _______</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>物种 2 _______</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>物种 3 _______</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>物种 4 _______</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>物种 5 _______</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>物种 6 _______</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td colspan="4">
			<h3></h3>
			<h3>小型树木</h3>
			</td>
		</tr>
		<tr>
			<td></td>
			<td>个体数量</td>
			<td>相对密度（%）</td>
			<td>密度<br>
			(株/公顷)</td>
		</tr>
		<tr>
			<td>物种 1 _______</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>物种 2 _______</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>物种 3 _______</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>物种 4 _______</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>物种 5 _______</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>物种 6 _______</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>
<p></p>
<p><strong>表1.</strong> 用于填写关于大树和小树密度信息的表格。</p>
<table border="1">
	<tbody>
		<tr>
			<td colspan="4">
			<h3></h3>
			<h3>大型树木</h3>
			</td>
		</tr>
		<tr>
			<td></td>
			<td>平均基部面积<br>
			 (m<sup>2</sup>)</td>
			<td>基部面积<br>
			(m<sup>2</sup>)</td>
			<td>相对基部面积</td>
		</tr>
		<tr>
			<td>物种 1 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>物种 2 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>物种 3 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>物种 4 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>物种 5 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>物种 6 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>总计</td>
			<td></td>
			<td>总基部面积 =</td>
			<td></td>
		</tr>
		<tr>
			<td colspan="4">
			<h3></h3>
			<h3>小型树木</h3>
			</td>
		</tr>
		<tr>
			<td></td>
			<td>平均基部面积<br>
			 (m<sup>2</sup>)</td>
			<td>基部面积<br>
			(m<sup>2</sup>)</td>
			<td>相对基部面积</td>
		</tr>
		<tr>
			<td>物种 1 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>物种 2 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>物种 3 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>物种 4 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>物种 5 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>物种 6 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>总计</td>
			<td></td>
			<td>总基部面积 =</td>
			<td></td>
		</tr>
	</tbody>
</table>
<p><strong>表2.</strong> 用于填写大、小树木基部面积相关信息的表格。</p>
<table border="1">
	<tbody>
		<tr>
			<td colspan="4">
			<h3></h3>
			<h3>大型树木</h3>
			</td>
		</tr>
		<tr>
			<td></td>
			<td>点数</td>
			<td>频数</td>
			<td>相对频数</td>
		</tr>
		<tr>
			<td>物种 1 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>物种 2 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>物种 3 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>物种 4 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>物种 5 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>物种 6 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>总计</td>
			<td></td>
			<td>总频数 =</td>
			<td></td>
		</tr>
		<tr>
			<td colspan="4">
			<h3></h3>
			<h3>小型树木</h3>
			</td>
		</tr>
		<tr>
			<td></td>
			<td>点数</td>
			<td>频数</td>
			<td>相对频数</td>
		</tr>
		<tr>
			<td>物种 1 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>物种 2 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>物种 3 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>物种 4 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>物种 5 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>物种 6 _______________</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>总计</td>
			<td></td>
			<td>总频数 =</td>
			<td></td>
		</tr>
	</tbody>
</table>
<p><strong>表3.</strong> 用于填写关于大树和小树出现频率信息的表格。</p>
<table border="1">
	<tbody>
		<tr>
			<td colspan="6">
			<h3></h3>
			<h3>大型树木</h3>
			</td>
		</tr>
		<tr>
			<td></td>
			<td>相对<br>
			密度</td>
			<td>相对<br>
			频度</td>
			<td>相对<br>
			基部<br>
			面积</td>
			<td>重要性<br>
			值</td>
			<td>相对<br>
			重要性<br>
			值</td>
		</tr>
		<tr>
			<td>物种 1 _______________</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>物种 2 _______________</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>物种 3 _______________</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>物种 4 _______________</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>物种 5 _______________</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>物种 6 _______________</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td>总重要性值 =</td>
			<td></td>
		</tr>
		<tr>
			<td colspan="6">
			<h3></h3>
			<h3>小型树木</h3>
			</td>
		</tr>
		<tr>
			<td></td>
			<td>相对<br>
			密度</td>
			<td>相对<br>
			频度</td>
			<td>相对<br>
			基部<br>
			面积</td>
			<td>重要性<br>
			值</td>
			<td>相对<br>
			重要性<br>
			值</td>
		</tr>
		<tr>
			<td>物种 1 _______________</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>物种 2 _______________</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>物种 3 _______________</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>物种 4 _______________</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>物种 5 _______________</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>物种 6 _______________</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td>总重要性值 =</td>
			<td></td>
		</tr>
	</tbody>
</table>
<p><strong>表4.</strong> 用于填写大、小树木的重要值和相对重要值相关信息的表格。</p>


<p class="jove_content">树木调查是公共和私人利益相关方的重要技术手段，可为土地管理者提供有益信息，帮助其做出科学决策。一个社区可能希望通过开展树木清查，来判断是否需要启动林业项目。例如，调查可能发现大量枯死或患病的树木（<strong>图3</strong>），从而表明需要补种更多树木。此外，调查结果还可帮助社区制定养护计划，以预防危险树木造成的损害。最后，调查有助于社区进行土地管理决策。了解森林中的物种多样性，可使管理者制定合理的种植规划（<strong>图4</strong>）。例如，可设定诸如“森林中占比超过x%的树种不再进行种植”的指导原则。</p>
<p class="jove_content">树木调查有助于量化森林作为自然资源的价值。了解森林结构可使森林管理者计算树木所提供服务的价值，例如控制空气污染、碳捕获与封存以及降低能源消耗。</p>
<p class="jove_content" fo:keep-together.within-page="always"><img alt="带有雾气的森林生态系统、树木生长阶段、环境研究、生态气候分析" src="/files/ftp_upload/10060/10060fig5.jpg" data-al...

树木调查：点中心四分法采样方法

<p class='jove_content'>有多种方法可用于森林群落的取样，点中心四分法是其中之一。该方法用于收集森林中树种的密度、频度和盖度信息。这些信息可用于估算所遇到的个体树木数量、某种树木出现的频率、该树种相对于其他树种的普遍程度以及树木的大小。与传统的样地分析法相比，点中心四分法效率更高，这是其主要优势。在固定面积样地取样中，仅对森林总面积的一小部分进行调查。在这一小块样地内，通过逐棵计数并鉴定每株树木来直接确定密度。利用样地面积与整个森林面积的比例关系，推算出整个森林的树木密度。</p>

<p class="jove_content">点中心四分之一个体树木调查法可产生三个定量指标：相对密度、相对频度和相对基部面积。这三个数值相加得到该物种的重要性值，然后将其转换为相对重要性值（<strong>表5</strong>）。</p>
<p class="jove_content">在仅发现一个物种存在的调查中，该物种的重要性值最高可达300。重要性值高并不一定意味着该物种对森林健康具有重要意义；它仅仅表示该物种目前在森林结构中占优势（<strong>图2</strong>）。</p>
<p class="jove_content">树木是一种重要的自然资源，有助于改善城市环境、促进健康并提升整体生活质量。因此，充分了解森林的组成对于维护这一资源至关重要。例如，如果森林具有较高的多样性，则有助于减轻特定物种的昆虫或疾病带来的影响。如果林下层出现大量入侵树种，则可能表明这些入侵树种正开始竞争并取代本地树种。</p>
<p class="jove_content" fo:keep-together.within-page="always"><img alt="柱状图比较索姆斯树林中大树和小树的重要性值。" src="/files/ftp_upload/10060/10060fi...

可用于采样森林群落的方法有多种，样点中心四分法便是其中之一。该方法用于收集有关……的信息

<p>树木调查对于评估森林生物多样性以及阐明林地的结构和健康状况具有重要意义。以点为中心的四分法采样是一种用于量化林地组成成分的常用技术。</p><p>林地是一种重要的自然资源，有助于维持生态环境，同时影响人类群体的健康和生活质量。深入了解森林的组成对于保护这一资源至关重要。如果森林具有较高的生物多样性，就能最大限度地减少专一性害虫或疾病带来的影响。如果入侵树种在林下层占据主导地位，则可能预示着未来本地树种将被取代。</p><p>点中心四分法取样是森林群落中常用的一种方法。该方法用于收集森林中树种的密度、频度和覆盖度信息。通过该方法获取的数据可用于估算树种出现的频率、不同树种的相对多度，以及树木的大小，进而估计树木的年龄及其在生态系统中所占据的空间。</p><p>点中心法相较于其他类型的树木调查具有优势。它比标准样地分析更高效，因为仅需在林地中进行少量取样，而无需调查所有现存树木。尽管所需人力较少，但已被证明能够提供可比的结果。</p><p>本视频将演示如何进行点中心四分法取样，如何计算相关的树木数据，以及如何分析点中心四分法树木调查的结果。</p><p>以点为中心的四分之一个样圆树木调查法可为特定树种提供三个主要的定量指标：相对密度、相对频度和相对基部面积。这三个数值相加后得到该树种的“重要值”，并可进一步换算为“相对重要值”。该数值可对某一树种在森林中的普遍程度和丰富度进行数值化的量化评估。</p><p>点中心四分法使用一种称为胸径（DBH）的树木测量指标，测量位置为现有地面以上4.5英尺处。在选定调查地点后，建立一条样线，在森林样线上的某一点被选定，并将该点周围区域划分为四个象限。在每个象限中，识别出距离最近且胸径大于40 cm的树木。这一组样本被视为大树样本。</p><p>接下来，在每个象限中，确定胸径大于 2.5 cm 但小于 40 cm 的最近树木。这些树木被标记为小树样本。在每个象限中分别识别大树和小树，可实现对上层高大、形成树冠的乔木植被与下层林下植被生长状况的比较。</p><p>通过这些简单的测量，可以计算出每种树种的胸高断面积（Basal Area）和重要值（Importance Value）。胸高断面积是指单株树木在胸高位置（DBH）的横截面积。计算某一树种所有个体的总胸高断面积是评估其物种密度更为准确的方法，该方法相较于单位面积内的树木数量，更能反映树木个体的大小差异。</p><p>通过计算每个物种的重要性值，可以估算某一物种在森林群落中的相对优势程度。该值综合考虑了物种在森林中的出现频率、该物种的个体总数，以及该物种所占据的森林总面积。</p><p>现在我们已经了解了树木调查的重要性以及点中心四分法调查的基本原理，接下来让我们看看这些方法在野外是如何实施的。</p><p>确定林地样地后，在森林中设置一条150米长的样线。样线可始于林地内的任意位置，但应尽量远离森林边缘，以尽量减少来自外部环境（如道路）的边界效应。</p><p>沿样线每隔 50 m 放置一根标桩。每根标桩代表四个罗盘方向的中心点，将采样地点划分为四个象限。如有需要，可从一端开始按位置顺序编号。</p><p>每个象限中，测量从桩点到任意物种直径大于40 cm的最近一棵树的距离。每个象限仅测量一棵大树，因此共记录16棵大树。每棵树均需记录其到桩点的距离，单位为厘米。</p><p>在每棵测量的树木上，记录其叶片为互生、轮生还是对生排列。然后，为每棵测量的树木采集叶片样本。</p><p>将叶片样品置于标本纸上，并根据采集地点进行标记，然后放入植物压片夹中以备后续鉴定。</p><p>对于每棵样木，使用野外测量卷尺记录其胸径（DBH）。若使用专用的胸径卷尺，可直接读取直径数值；若使用普通测量卷尺，则测量树干周长，再利用公式计算直径。</p><p>接下来，对每条样线的每个区段，分别测量距离最近的、直径小于 40 cm 且大于 2.5 cm 的树木在各个象限的相应数值。将这些数据记录在另一个类别中，标记为小树。</p><p>返回实验室后，计算每个物种的平均点到树的距离、密度和基部面积。然后可利用这些信息计算重要值。首先，使用树木鉴定指南或鉴定检索表，鉴定出在大树和小树类别中测量的每一种树木。</p><p>计算大、小树木整个样本的平均点到树木距离。该值即为树木组到样线点的平均距离。</p><p>接下来，使用所示公式计算大树组和小树组的平均密度，即每公顷树木数量。记录每组中每个树种的个体数量，然后分别计算大树组和小树组中各树种的密度。</p><p>将所有采样树木的直径测量值转换为面积。通过计算平均值，得出每个物种的平均基部面积。某个物种的基部面积等于该物种的平均基部面积乘以其密度。接下来，针对每个物种，计算其相对基部面积。</p><p>确定每个物种在每组中出现的频率。该频率通过比较该物种在4个采样点中出现的点数来确定。例如，若在某个象限的4个点位均发现美洲榆树，则其频率等于1；若银枫在4个点位中的2个被发现，则其频率为0.5。接下来，计算每个物种在每组中的相对频率。</p><p>现在可以计算物种的重要性值。将相对密度、相对频度和相对基部面积相加。最后，确定每个物种的相对重要性值。</p><p>总结来说，将这些数据输入图表中，以 Y 轴表示每个物种的重要性值，并按重要性递增的顺序排列，X 轴表示物种名称。数据应以两个柱状条呈现：一个代表大树，另一个代表小树。</p><p>在仅观察到一种树木物种的调查中，该物种的重要性值最高可达300。重要性值高并不一定意味着该物种对森林健康具有重要意义，而仅仅表明该物种目前在森林结构中占优势地位。</p><p>树木调查可用于向科学家或土地管理者提供多种重要信息。中心点四分法可应用于多种信息采集场景。</p><p>如果当地林地中枯死或患病树木的出现频率较高，社区可通过树木清查来评估是否需要开展林业项目。这类树木可能因枝条坠落而构成健康风险，或对其他树木造成感染风险。在森林中发现大量枯死或患病树木会引起环境科学家的关注，并可能表明存在不良环境状况的早期迹象，包括酸雨或臭氧污染。</p><p>了解森林中的物种多样性有助于土地管理者制定植树策略。管理者可据此设定指导方针，限制或减少常见树种的种植，同时引入新的或稀有的有益树种，以维持生物多样性。树木调查数据还可帮助管理者计算特定树种所提供生态服务的价值，例如控制空气污染或碳捕获与封存，并基于这些数据调整植树策略。</p><p>您刚刚观看了JoVE关于使用点中心四分法进行树木调查的简介视频。现在，您应该理解了树木调查的重要性、如何开展点中心四分法调查，以及如何根据调查测量数据计算森林结构。感谢观看！</p>

Education

教育

JoVE Science Education

Environmental Sciences

环境科学

树调查: 点本季度抽样方法

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...

tree survey: point-centered quarter sampling method

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

该集合利用跨学科的方法来探索和评价环境系统, 题目包括土壤和水污染物、侵入物种、替代能源和林业。

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 ...

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 ...

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

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