我们感谢美国凯斯西储大学的乡绅Valleevue和谷岭农场，包括A. LOCCI，C.债券，和A. Alldridge，帮助建立公共花园。 J.挂钩，L.霍夫曼，L.冈萨雷斯，资深大律师莱希，B. Ochocki，A. Ubiles，三宇，十赵，和NM齐默尔曼提供现场协助。 AJB和JHB由启动资金来自凯斯西储大学到JHBGAD资助是由暑期课程在本科生科研津贴从凯斯西储大学的霍华德·休斯医学研究所的资助支持。这项工作也是由美国国家科学基金会的资助，以JHB（DEB 1250170）的支持。

1。收集现场土壤，产生异构和同构土壤处理<ol><li>识别两个cooccurring植物类似的栖息地和土壤类型的研究（ 例如 图1a）。确定的量的土壤需要根据土壤的贴片尺寸的实验（ 例如三分之一到二分之一的焦点物种的初生根区域或体积由根球包含的）和实验所需的补丁的数量使用（参见方案2和3，下面）。 <ol><li>对于鲁梅克斯属。 （ 图1a），使用10厘米土壤斑块×10cm的x 18厘米（长x宽x深）为10厘米半径从植物的基部至18厘米深的近似根区（5655厘米3个土从这个定义中区一个单独的植物根系产生影响1,800 立方厘米 ）3土壤斑块。 </li></ol></li><li>调查野外现场找到两个重点物种的成年个体。避免个人的袋鼠T区可能重叠与其他重点物种（位于内的其他物种为0.25m 如鲁梅克斯个人）。标记需要获得所需的土壤的量与针标志的个体的数量。 <ol><li>马克20随机选择各酸模属的个体。 20试点单位（2种×2土壤处理×5个重复），每个需要来自各重点品种3个土补丁（如在协议2，下图）。 </li></ol></li><li>消毒土壤采集设备（铁锹，手套，运输容器）用漂白剂的约1点10分混合物（5-10％次氯酸钠）和水以去除所有土壤颗粒。使用前干燥设备，以避免对土壤生物漂白效果。标签每件设备与实验室磁带指示重点物种，其土壤它将收集或运输，以避免交叉污染（ 如标签1铲物种A和第二铲物种B）。 </li><li>检查天气和土壤条件土壤开始收集近期降水事件之前，系统蒸发散。避免收集土壤过于潮湿（泥泞或完全饱和），或在降雨事件，以减少土壤板结采集土壤。避免收集土壤过于干燥（非常坚硬，不易插入铲进）从根部土壤中分离到帮助。 </li><li>收集田间土壤从两个焦点物种的重复分批个人标记，以避免pseudoreplication（ 例如含有一种罕见的致病菌整个实验重复随后被混合的一个土壤样品）。 <ol><li>挖种A（定义见步骤1.1）与适当标记的无菌铲，从与适当标记的无菌手套土壤去除可见的粗根，然后将土壤中的适当标记的个体的完整的根区无菌运输容器（ 如桶）。对于实验4实验台，每个块和1株的根区提供足够的土壤1实验装置（如第1.2.1节），重复此过程物种A的另外3个人</li><li>物种B。重复第1.5.1节</li><li>从两个物种传递复制的土壤收集到的实验场地。放置在土壤实验单位为实验的块1（如在方案2或3，下图），其中一个块中包含从每个处理组合的实验单元（ 即各物质X的每个土壤处理）。 </li><li>重复第1.5.3节。 </li><li>在实验中剩余的数据块重复第1.5.1-1.5.4。从个人团体至少1米以前每次采集地点遥远的复制项目的集合，以尽量减少pseudoreplication收集的土壤。 </li></ol></li></ol><img alt="图1" fo:content-width="6in" src="/files/ftp_upload/51580/51580fig1highres.jpg" width="500" /> FIGUR区1。实例字段的实验设计操纵植物诱导土壤的异质性。（ 一 ）土壤是从同种（α）和heterospecifics（β）中的字段的根影响的区域收集，下列标准协议用 ​​于研究植物的土壤的效果进行反馈9 。 （b）与来自植物A（α土壤）土壤组成的非均匀土壤和植物乙（&#39;β&#39;土）土的试验治疗是排列在网格中，并与来自这两个来源的土壤的等量混合物中创建均质土壤处理。在这个例子中，字段的土壤栅格插入凹陷入地面的大直径盆和每个网格周围的区域填充有粗，灭菌砂。这个数字已经被修改勃兰特等人 10 2。一个例子田间试验，建立异构和同构土壤网格来衡量植物种群回复<ol><li>使用土壤从复制田间土壤采集（协议1）产生一个异类治疗（ 即交替网格单元包含土壤物种或物种乙收集），并均匀处理（ 即每个网格单元包含土为1:1的混合物从物种A和B）（ 图1b）用于实验在以下步骤中的数据块1。 <ol><li>土壤消毒处理设备（镘刀，手套，塑料网格）与漂白剂的约1点10分混合物（5-10％次氯酸钠）和水以去除所有土壤颗粒。使用前干燥设备，以避免对土壤生物漂白效果。标签每件设备与实验室磁带指示重点物种的土壤它会处理，以避免交叉污染（ 如标签1抹子物种A和第二抹子物种B）和塑料格栅，以表明它是否将使用对异构或同构土壤处理。 </li><li>将可拆卸的塑料格栅进沉没入地[或其他情节或容器足够大，可以容纳电网]要充满领域的锅采集的土壤（ 如 1800厘米3 /网格单元如步骤1.1.1）。使用所需的尺寸， 例如 ，一个2×3网格的尺寸的6个细胞在步骤1.1确定的一个自定义的构造的网格（ 图1b）。 <ol><li>对于异构处理土壤交替斑块类型，土壤种类A的地方spadefuls成网格单元为α土壤和种乙土壤进入细胞内的β土（ 图1b）。 </li><li>对于均质处理，将土壤A和B交替spadefuls到每个网格单元，同时注意均匀分布两种土壤类型，避免各土壤类型的层的形成（ 图1b）。为1800厘米3的例子土壤补丁（1.1.1节），将每个土壤类型为900 立方厘米在每个网格单元。 </li><li>是SURE产生干扰等量（ 即分手土土块到相同的程度）创建异类和同类土壤处理时，为避免混淆土壤扰动土壤的异质性。 </li></ol></li><li>如果有任何空白区域仍然围绕电网的外内使用（如在图1b）的大锅里，填补了这一领域，用无菌沙子。使用任何标准的方法（ 如高压灭菌，γ-照射）消毒沙子。 </li><li>提起塑料格栅垂直出锅，留在土壤补丁完好无损。这允许来自不同个体的根在土壤中，每个工厂交互体验多个补丁，这是用于使植物的根生长成多个土壤斑块（ 即网格单元）是必不可少的。 </li><li>重复第2.1.2-2.1.4的第二对试点单位产生一个完整的实验块（ 即混合土的网格成种植每福卡l种类和均质土成植物各重点品种，共计4试点单位）的网格。 </li></ol></li><li>在实验中，其余剩下的泥土块重复步骤2.1复制集合（协议1）。块内的随机块，并重复整个实验区，利用周围如果需要，重复横向织物，以保持遮阳从外植在最低限度（未示出）。 </li><li>植物种子重点物种的进入每个实验锅（2焦点物种×2土壤处理）的每个网格单元。使用共用的种子，以避免混淆基因型植物或种子表面微生物群落与土壤处理。例如，植物种子每羊蹄属植物。放入锅中该物种（ 图1a）分别粘在塑料牙签用水溶性胶水在12种职位（每个网格单元的2个位置），以清楚地识别个体种植。 </li><li>衡量人口水库实验单位，如发芽和生存，通过个人的定期普查的ponses标志着种子的种植地点（ 例如，使用牙签如步骤2.3）。尽量减少土壤测量，以避免土壤混合斑块之间的任何响应的干扰。 <ol><li>确定基于对重点物种种群反应的预期收益率相应的普查间隔。例如，每周进行普查的鲁梅克斯属。能迅速发芽。 </li><li>继续实验的基础上，重点物种的生活史一个适当的时间。例如，继续实验至少2年短暂的常年酸模属。获得所有生命阶段的数据。 </li></ol></li></ol> 3。一个例子温室实验，在花盆异构和均质土壤衡量个人植物影响<ol><li>使用从复制田间土壤集合（协议1）土壤产生异质性处理（填充用土从一个物种或物种乙收集了锅，即各占一半）和均匀处理（ 即锅含有土壤的物种A和B的1:1混合物）（ 图2a）块1实验在下面的步骤中。 <ol><li>在运输容器（ 如桶）和灌封前，混合场采集的土壤从每个物种用无菌砂生产1:1的混合物。为此，以减轻土壤板结和改善排水盆，它是用于清洗根部特别有用，促进根系从土壤中分离。使用任何标准的方法（ 如高压灭菌，γ-照射）消毒沙子。 </li><li>一定要产生干扰等量（ 即分手土土块到相同的程度）混合每批田间土壤砂时。 </li></ol></li><li>土壤消毒处理设备（镘刀，手套，塑料片材）与AP漂白剂的近因1:10混合物（5-10％次氯酸钠）和水以去除所有土壤颗粒。使用前干燥设备，以避免对土壤生物漂白效果。标签每件设备与实验室磁带指示重点物种的土壤它会处理，以避免交叉污染（ 如标签1抹子物种A和第二抹子物种B）和硬塑料片的每一面，以指示哪些土壤类型将在异质土壤处理盆栽在它的两侧。 </li><li>创建一个使用来自两个重点物种（从第3.1.1节）的田间土壤砂混合物异构土壤处理。 <ol><li>将硬塑料片在一个锅里中心划分成两半（ 图2a）。使用锅的大小吧，这样一半是在体积等同于相应的土壤斑块大小（步骤1.1）。例如，使用一个锅一个直径为15厘米和18厘米深的土大黄属。在图1a中 （总体积为3181厘米3）。 </li><li>有两个研究人员同时从每个品种（从物种如 α土）与适当标记的镘刀加场采集的土壤锅的正确一侧，以保持双方甚至在锅里装满。 </li><li>通过垂直抬起，土壤，离开土壤斑块完好卸下塑料护栏。这使得工厂体验到土壤内锅两个补丁，用于植物必需经历的异质性。 </li><li>重复第3.3.1-3.3.3 3个额外的试点单位，以产生非均质土壤处理一个完整的块（2种×2土壤补丁中的异类治疗类型， 图2）。 </li></ol></li><li>创建一个使用来自两个重点物种（从第3.1.1节）的田间土壤砂混合物均匀土壤处理。 <ol><li>重复第3.3.1节。有两个研究人员同时添加α和β的土壤既用适当标记的镘刀，均匀地分布在每个色块内两种土壤类型和避免产生层的锅面。重复第3.3.3节。 </li><li>重复第3.4.1节的第二个试点单位，以产生均匀的土壤处理（一锅为每2个重点物种的）的一个完整的块。 </li></ol></li><li>对于剩余的块在实验中，其余土壤重复步骤3.2-3.4复制集合（协议1）。块中的随机块，地块，整个温室的长凳上。 </li></ol><img alt="图2" fo:content-width="6in" src="/files/ftp_upload/51580/51580fig2highres.jpg" width="500" /> 图2。例如温室实验设计操纵植物引起的土壤异质性。（一 ）从物种A的根影响力在该领域的区域（α土壤）和物种B（β土）采集土壤是地方D在一壶茶（异构处理）各占一半，或整个锅（均质处理）混合。 （二）物种A的植物，然后种植到实验中各土壤接插型的异构治疗和均质处理的一侧。这里，只有一个物种（A）示出植入这种设计。一个完全对等的设计将包括种植到内非均质处理各土壤处理和贴片式第二焦点物种（B）的植物。 <ol start="6"><li>重点物种A和B到每个土壤斑块类型的析因设计的植物幼苗（2种×3的土壤斑块类型[α土壤，土壤β，α和β土的均匀混合物]; 图2b）。 </li><li>测量任何单个工厂的答复表明，设备性能，如工厂规模，生物质生产，或功能特性。适当的特征来衡量取决于重点物种和科学问题兴趣。 <ol><li>继续实验，直到植物大相出现土壤斑块（ 例如约1.5倍的土壤补丁花环形成杂类草的宽度），以确保植物的根都长成这两种土壤补丁。因此，实验持续时间将取决于重点物种的生长速度。 </li><li>收获的植物和/或测量响应之前成为植物盆栽绑定，如果现实的反应，土壤环境是理想的（ 即根的生长是由锅和根圆锅底的范围限制）。例如，锅结合的植物的根系是不可能在整个以类似的方式在土壤柱觅食，在该领域的植物。 </li></ol></li></ol>

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N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Feedback+with+soil+biota+contributes+to+plant+rarity+and+invasiveness+in+communities.">Feedback with soil biota contributes to plant rarity and invasiveness in communities.</a> Nature. 417, 67-70 (2002).</li><li>Mommer, L., van Ruijven, J., Jansen, C., van de Steeg, H. M., de Kroon, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interactive+effects+of+nutrient+heterogeneity+and+competition:+implications+for+root+foraging+theory?.">Interactive effects of nutrient heterogeneity and competition: implications for root foraging theory?.</a> Funct. Ecol. 26, 66-73 (2012).</li><li>Felsenstein, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Phylogenies+and+the+comparative+method.">Phylogenies and the comparative method.</a> Am. Natural. 125, 1-15 (1985).</li><li>Burns, J. H., Strauss, S. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=More+closely+related+species+are+more+ecologically+similar+in+an+experimental+test.">More closely related species are more ecologically similar in an experimental test.</a> Proc. Natl. Acad. Sci. U.S.A. 108, 5302-5307 (2011).</li><li>Fukami, T., Nakajima, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Community+assembly:+alternative+stable+states+or+alternative+transient+states.">Community assembly: alternative stable states or alternative transient states.</a> Ecol. Lett. 14, 973-984 (2011).</li></ol>

作者什么都没有透露。

植物引起的土壤异质性极有可能在自然群落的植物，因为对它们的土壤环境中的大型和经常特定物种的影响和体验，土壤（ 如彼得曼等 13）随后的植物。然而，我们这种类型的异质性对植物群落的角色的理解是最小的10,14。在这里，我们提出了操纵植物引起的土壤异质性，利用土壤不同来源（不同树种根系的影响，即区域）在该领域的方法。在协议中的关键步...

一个群落生态学的主要目标是解释和预测管辖社区组装的过程。然而，植物群落往往比预测的共存理论更多的多样化，并恢复生态学家需要了解的共存机制，成功还原多样化当地社区2。环境异质性是可以帮助解释高水平群落多样性的一个理论上的重要机制，但非均质性的实验操作是罕见3，专注于非生物异质性（ 例如，在Lundholm 4日 ）。理论，结合异质性通常假定异质性是外在的组装社区。外在的异质性是由因素，如景观类型学，它是独立的群落组成的管辖。外在的异质性可以通过生态位分化（里维会导致共处星期三在墨尔本等。3，如帕卡拉和蒂尔曼5和切森6）。然而，还有许多相关的植物群落对环境的异质性可能是内在的社会，发展成为社会各界及组装根据物种在社会上的身份。内在的异质性可导致生物反馈，可通过负的频率依赖性（ 如贝沃等。7）导致共存。在这里，我们描述了操纵植物引起的土壤异质性，一个类型的土壤异质性是固有的社会和来自植物 - 土壤反馈的新方法。 植物-土壤反馈（PSF）发生时，植物影响土壤结构，化学，生物或在影响着土壤后续工厂绩效的方式，和PSF对原生植物群落8工厂性能大的平均效应。涤纶短纤的研究通常是收集来自现场的土壤或土壤条件实验，然后问植物在土壤中相对同种的表现如何，以异种或灭菌土9。如果植物在土壤相对同种更好的表现来引用的土壤，然后PSF是积极的，而如果植物在土壤中引用有更好的表现，PSF是否定的。友情负PSF可以导致物种7之间的频率依赖性并存。而PSF的平均效果是充分表征8，空间异质性在PSF的影响知之甚少10。 由于PSF发生在个别工厂7的规模和因为植物往往是非随机分布在空间和时间，涤纶短纤有可能导致土壤异质性，我们称之为植物引起的土壤异质性 。不像许多其他形式的异质性（ 如风景的拓扑结构），这heterogeneity是固有的装配社区，从而可能影响社会装配不同于异质性更外在形式。为了了解这种形式的异质性对植物的性能和共存的影响，我们需要操纵植物引起的土壤异质性的实验方法。在这里，我们展示了这样一种方法，即用土壤的两个物种空调创建具有两个土起源和均质处理，这是两个土起源的混合物单独的补丁异构处理。这种土壤混合可以代表在现场至少有两个可能的情况下：（1）干扰（ 如啮齿类动物，农业），其中混合不同来源的土壤或两种接近的成长（2）植物，使得根系影响其区域交融，均质。 我们目前使用的植物引起的土壤异质性在不同LEVE回答关键问题的两个示例实验生态组织的LS：（1）不要植物种群应对种植引起的土壤异质性？及（2）不要单独植物植物引起的土壤异质性反应？我们描述了现场实验用6土壤补丁使用2土壤补丁来解决第二个问题，解决的第一个问题和一个温室试验。量化人口和个别植物对土壤异质性是必不可少的理解异质性影响的社区如何组装。

<table border="0" cellpadding="0" cellspacing="0" width="1119">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Shovel(s)</td>
			<td style="width:136px;">Any</td>
			<td style="width:71px;">NA</td>
			<td style="width:696px;">It is helpful to have at least two shovels, one for each species of soil origin.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Trowel(s)</td>
			<td style="width:136px;">Any</td>
			<td style="width:71px;">NA</td>
			<td style="width:696px;">It is necessary to have at least two trowels of identical size, one for each species of soil origin.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Gloves</td>
			<td style="width:136px;">Any</td>
			<td style="width:71px;">NA</td>
			<td style="width:696px;">Gardening gloves can be used.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Diluted bleach</td>
			<td style="width:136px;">Any</td>
			<td style="width:71px;">NA</td>
			<td style="width:696px;">We use an ~1:10 concentration of household bleach (containing 5-10% NaClO) to water to sterilize all equipment between soil collections.</td>
		</tr>
		<tr height="50">
			<td height="50" style="height:50px;width:216px;">Plastic grid(s)</td>
			<td style="width:136px;">Any</td>
			<td style="width:71px;">NA</td>
			<td style="width:696px;">CUSTOM. We used plastic sheeting from the construction of greenhouse walls to create the grid used in the field experiment. However any stiff plastic that can be manipulated can be used. It is helpful to have three grids to produce reciprocal heterogeneous treatments and a homogeneous treatment without needing to sterilize between each experimental unit.</td>
		</tr>
		<tr height="47">
			<td height="47" style="height:47px;width:216px;">Plastic dividers</td>
			<td style="width:136px;">Any</td>
			<td style="width:71px;">NA</td>
			<td style="width:696px;">CUSTOM. We used stiff sheets of plastic, cut to fit the pot minimum width, such that they can slide down to the bottom of the pot for the greenhouse experiment. It is helpful to have at least two dividers, one for heterogeneous and one for homogeneous treatments, if investigators want to randomize the order in which experimental units within a block are filled without needing to sterilize the divider in between each experimental unit.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Buckets or wheelbarrows</td>
			<td style="width:136px;">Any</td>
			<td style="width:71px;">NA</td>
			<td style="width:696px;">Any container for transporting soils.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Seeds</td>
			<td style="width:136px;">Any</td>
			<td style="width:71px;">NA</td>
			<td style="width:696px;">We collect seeds in the field by hand. Seeds can also be ordered from horticultural suppliers, if appropriate.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Plastic toothpicks</td>
			<td style="width:136px;">Soodhalter Plastics, Inc.</td>
			<td>805KP</td>
			<td style="width:696px;">We plant individual seeds glued on toothpick in the field experiment, to facilitate monitoring germination and survival of individuals.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Water soluble glue</td>
			<td style="width:136px;">Elmer&#39;s</td>
			<td style="width:71px;">Elmer&#39;s Glue-all</td>
			<td style="width:696px;">Any water soluble glue can be used to adhere seeds to plastic toothpicks.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Pots</td>
			<td style="width:136px;">Any</td>
			<td style="width:71px;">NA</td>
			<td style="width:696px;">Pot size will depend on experimental plants used and number of soil patches desired (e.g. 2 or 6).</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Sand</td>
			<td style="width:136px;">Any</td>
			<td style="width:71px;">NA</td>
			<td style="width:696px;">Coarse sand may be mixed with field soils to improve drainage in pots.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Lab tape&#160;</td>
			<td style="width:136px;">Any</td>
			<td style="width:71px;">NA</td>
			<td style="width:696px;">Tape may be used to label equipment used in handling soils with the species of origin.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Pin flags</td>
			<td style="width:136px;">Any</td>
			<td style="width:71px;">NA</td>
			<td style="width:696px;">Flags can be used to identify individuals in the field, prior to soil collection.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Landscape fabric</td>
			<td style="width:136px;">Any</td>
			<td style="width:71px;">NA</td>
			<td style="width:696px;">Landscape fabric can be used in the field to minimize the growth of plants outside experimental plots.</td>
		</tr>
	</tbody>
</table>

experimental protocol for manipulating plant-induced soil heterogeneity

共存理论常常被环境异质性作为独立的群落组成的，但生物反馈，如植物 - 土壤反馈（PSF）对植物的性能有很大的影响，并创造环境异质性依赖于群落组成。理解的PSF对植物群落组件的重要性就必须异质性的PSF的作用，除了意味着PSF作用的理解。在这里，我们描述了一个协议，用于操纵植物引起的土壤异质性。两个实验的例子给出：（1）现场实验用6片栅格的土壤测量植物种群的反应和（2）的温室实验2补丁土壤测量单株反应。土壤可以从根影响（从根圈土壤和直接相邻的根际）领域植物从同种和异种的植物物种的区被收集。复制收集离子被用来避免pseudoreplicating土壤样品。这些土壤，然后放入异构治疗或混合的均匀化处理单独的补丁。应注意，以确保异质和同质化的治疗体会土壤扰动程度相同。植物可以被放置在这些土壤处理，以确定植物引起的土壤异质性对设备性能的影响。我们证明了植物诱导异质性的结果，也许是因为这些反馈的动态性质不同的结果比预测由传统的共存模式。理论，结合环境异质性的装配社区和额外的实证工作的影响是必要的，以确定何时异质性内在的组装社会将导致与外在的异质性对群落组成比较不同的装配结果。

种反应以种植引起的土壤异质性不同的方式在人口和个体水平（ 图3和图4），与社区组装的影响。要确定植物种群是否对植物引起的土壤异质性反应，现场试验，采用三对同类物种的确立为协议2。植物种群censused每周三个月，并种植种子发芽和那些苗的总比例，在第一个生长季死亡（其中死亡率表示的生存的倒数）进行计算（ 图3）的总比例。我们发现有显?...

Watch this Scientific Journal Video about Experimental Protocol for Manipulating Plant-induced Soil Heterogeneity at JoVE.com

Experimental Protocol for Manipulating Plant-induced Soil Heterogeneity | Environment | Video

Experimental Protocol for Manipulating Plant-induced Soil Heterogeneity

理解物种共存的环境异质性的作用通常专注于各类异质性是外在的社会的物种组成。我们提供新的详细的方法使用土壤受植物 - 土壤反馈调节，或异质性固有的群落组成产生土壤异质性的治疗方法。

用于操纵植物诱导土壤异质性的实验协议

Coexistence theory has often treated environmental heterogeneity as being independent of the community composition; however biotic feedbacks such as ...

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18.6K 次观看.  Case Western Reserve University. 理解物种共存的环境异质性的作用通常专注于各类异质性是外在的社会的物种组成。我们提供新的详细的方法使用土壤受植物 - 土壤反馈调节，或异质性固有的群落组成产生土壤异质性的治疗方法。 

视频: Experimental Protocol for Manipulating Plant-induced Soil Heterogeneity

Design and Operation of a Continuous 13C and 15N Labeling Chamber for Uniform or Differential, Metabolic and Structural, Plant Isotope Labeling

Tracing rare stable isotopes from plant material through the ecosystem provides the most sensitive information about ecosystem processes; from CO2 fluxes and soil organic matter formation to small-scale stable-isotope biomarker probing. Coupling multiple stable isotopes such as 13C with 15N, 18O or&#160;2H has the potential to reveal even more information about complex stoichiometric relationships during biogeochemical transformations. Isotope labeled plant material has been used in various studies of litter decomposition and soil organic matter formation1-4. From these and other studies, however, it has become apparent that structural components of plant material behave differently than metabolic components (i.e. leachable low molecular weight compounds) in terms of microbial utilization and long-term carbon storage5-7. The ability to study structural and metabolic components separately provides a powerful new tool for advancing the forefront of ecosystem biogeochemical studies. Here we describe a method for producing 13C and 15N labeled plant material that is either uniformly labeled throughout the plant or differentially labeled in structural and metabolic plant components.
Here, we present the construction and operation of a continuous 13C and 15N labeling chamber that can be modified to meet various research needs. Uniformly labeled plant material is produced by continuous labeling from seedling to harvest, while differential labeling is achieved by removing the growing plants from the chamber weeks prior to harvest. Representative results from growing Andropogon gerardii Kaw demonstrate the system&#39;s ability to efficiently label plant material at the targeted levels. Through this method we have produced plant material with a 4.4 atom%13C and 6.7 atom%15N uniform plant label, or material that is differentially labeled by up to 1.29 atom%13C and 0.56 atom%15N in its metabolic and structural components (hot water extractable and hot water residual components, respectively). Challenges lie in maintaining proper temperature, humidity, CO2 concentration,&#160;and light levels in an airtight 13C-CO2 atmosphere for successful plant production. This chamber description represents a useful research tool to effectively produce uniformly or differentially multi-isotope labeled plant material for use in experiments on ecosystem biogeochemical cycling.

Design and Operation of a Continuous 13C and 15N Labeling Chamber for Uniform or Differential, Metabolic and Structural, Plant Isotope Labeling

This method explains how to build and operate a continuous 13C and 15N isotope labeling chamber for uniform or differential plant tissue labeling. Representative results from metabolic and structural labeling of Andropogon gerardii are discussed.

设计一个连续和操作<sup&gt; 13</sup&gt; C和<sup&gt; 15</sup&gt;Ñ贴标商会统一或差分，代谢和结构，植物同位素标记

Tracing rare stable isotopes from plant material through the ecosystem provides the most sensitive information about ecosystem processes; from CO2 fluxes ...

科研

环境科学

A Protocol for Conducting Rainfall Simulation to Study Soil Runoff

Rainfall is a driving force for the transport of environmental contaminants from agricultural soils to surficial water bodies via surface runoff. The objective of this study was to characterize the effects of antecedent soil moisture content on the fate and transport of surface applied commercial urea, a common form of nitrogen (N) fertilizer, following a rainfall event that occurs within 24&#160;hr&#160;after fertilizer application. Although urea is assumed to be readily hydrolyzed to ammonium and therefore not often available for transport, recent studies suggest that urea can be transported from agricultural soils to coastal waters where it is implicated in harmful algal blooms. A rainfall simulator was used to apply a consistent rate of uniform rainfall across packed soil boxes that had been prewetted to different soil moisture contents. By controlling rainfall and soil physical characteristics, the effects of antecedent soil moisture on urea loss were isolated. Wetter soils exhibited shorter time from rainfall initiation to runoff initiation, greater total volume of runoff, higher urea concentrations in runoff, and greater mass loadings of urea in runoff. These results also demonstrate the importance of controlling for antecedent soil moisture content in studies designed to isolate other variables, such as soil physical or chemical characteristics, slope, soil cover, management, or rainfall characteristics. Because rainfall simulators are designed to deliver raindrops of similar size and velocity as natural rainfall, studies conducted under a standardized protocol can yield valuable data that, in turn, can be used to develop models for predicting the fate and transport of pollutants in runoff.

A rainfall simulator was used to apply a consistent rate of uniform rainfall to packed soil boxes in a study of the fate and transport of urea, a nonpoint source environmental contaminant. Under uniform soil and rainfall conditions, antecedent soil moisture content exerted strong control over urea loss in surface runoff.

一个协议，用于开展降雨模拟研究土壤径流

Rainfall is a driving force for the transport of environmental contaminants from agricultural soils to surficial water bodies via surface runoff. The ...

A Protocol for Collecting and Constructing Soil Core Lysimeters

Leaching of nutrients from land applied fertilizers and manure used in agriculture can lead to accelerated eutrophication of surface water. Because the landscape has complex and varied soil morphology, an accompanying disparity in flow paths for leachate through the soil macropore and matrix structure is present. The rate of flow through these paths is further affected by antecedent soil moisture. Lysimeters are used to quantify flow rate, volume of water and concentration of nutrients leaching downward through soils. While many lysimeter designs exist, accurately determining the volume of water and mass balance of nutrients is best accomplished with bounded lysimeters that leave the natural soil structure intact. 
Here we present a detailed method for the extraction and construction of soil core lysimeters equipped with soil moisture sensors at 5 cm and 25 cm depths. Lysimeters from four different Coastal Plain soils (Bojac, Evesboro, Quindocqua and Sassafras) were collected on the Delmarva Peninsula and moved to an indoor climate controlled facility. Soils were irrigated once weekly with the equivalent of 2 cm of rainfall to draw down soil nitrate-N concentrations. At the end of the draw down period, poultry litter was applied (162 kg TN ha-1) and leaching was resumed for an additional five weeks. Total recovery of applied irrigation water varied from 71% to 85%. Nitrate-N concentration varied over the course of the study from an average of 27.1 mg L-1 before litter application to 40.3 mg L-1 following litter application. While greatest flux of nutrients was measured in soils dominated by coarse sand (Sassafras) the greatest immediate flux occurred from the finest textured soil with pronounced macropore development (Quindocqua).

A detailed method for extraction and assembly of intact soil core lysimeters and their use for study of leachate and associated loss of nutrients from surface applied poultry litter is demonstrated.

一种用于收集和构建土芯协议测渗计

Leaching of nutrients from land applied fertilizers and manure used in agriculture can lead to accelerated eutrophication of surface water. Because the ...

Experimental Protocol for Biodiesel Production with Isolation of Alkenones as Coproducts from Commercial Isochrysis Algal Biomass

The need to replace petroleum fuels with alternatives from renewable and more environmentally sustainable sources is of growing importance. Biomass-derived biofuels have gained considerable attention in this regard, however first generation biofuels from edible crops like corn ethanol or soybean biodiesel have generally fallen out of favor. There is thus great interest in the development of methods for the production of liquid fuels from domestic and superior non-edible sources. Here we describe a detailed procedure for the production of a purified biodiesel from the marine microalgae Isochrysis. Additionally, a unique suite of lipids known as polyunsaturated long-chain alkenones are isolated in parallel as potentially valuable coproducts to offset the cost of biodiesel production. Multi-kilogram quantities of Isochrysis are purchased from two commercial sources, one as a wet paste (80% water) that is first dried prior to processing, and the other a dry milled powder (95% dry). Lipids are extracted with hexanes in a Soxhlet apparatus to produce an algal oil (&#34;hexane algal oil&#34;) containing both traditional fats (i.e., triglycerides, 46-60% w/w) and alkenones (16-25% w/w). Saponification of the triglycerides in the algal oil allows for separation of the resulting free fatty acids (FFAs) from alkenone-containing neutral lipids. FFAs are then converted to biodiesel (i.e., fatty acid methyl esters, FAMEs) by acid-catalyzed esterification while alkenones are isolated and purified from the neutral lipids by crystallization. We demonstrate that biodiesel from both commercial Isochrysis biomasses have similar but not identical FAME profiles, characterized by elevated polyunsaturated fatty acid contents (approximately 40% w/w). Yields of biodiesel were consistently higher when starting from the Isochrysis wet paste (12% w/w vs. 7% w/w), which can be traced to lower amounts of hexane algal oil obtained from the powdered Isochrysis product.

Experimental Protocol for Biodiesel Production with Isolation of Alkenones as Coproducts from Commercial Isochrysis Algal Biomass

Detailed methods are presented for the production of biodiesel along with the co-isolation of alkenones as valuable coproducts from commercial Isochrysis microalgae.

实验协议生产生物柴油与饱和酮的分离从商业余积<em&gt;等鞭金藻</em&gt;藻类生物量

The need to replace petroleum fuels with alternatives from renewable and more environmentally sustainable sources is of growing importance. ...

A Gusseted Thermogradient Table to Control Soil Temperatures for Evaluating Plant Growth and Monitoring Soil Processes

Thermogradient tables were first developed in the 1950s primarily to test seed germination over a range of temperatures simultaneously without using a series of incubators. A temperature gradient is passively established across the surface of the table between the heated and cooled ends and is lost quickly at distances above the surface. Since temperature is only controlled on the table surface, experiments are restricted to shallow containers, such as Petri dishes, placed on the table. Welding continuous aluminum vertical strips or gussets perpendicular to the surface of a table enables temperature control in depth via convective heat flow. Soil in the channels between gussets was maintained across a gradient of temperatures allowing a greater diversity of experimentation. The gusseted design was evaluated by germinating oat, lettuce, tomato, and melon seeds. Soil temperatures were monitored using individual, battery-powered dataloggers positioned across the table. LED lights installed in the lids or along the sides of the gradient table create a controlled temperature chamber where seedlings can be grown over a range of temperatures. The gusseted design enabled accurate determination of optimum temperatures for fastest germination rate and the highest percentage germination for each species. Germination information from gradient table experiments can help predict seed germination and seedling growth under the adverse soil conditions often encountered during field crop production. Temperature effects on seed germination, seedling growth, and soil ecology can be tested under controlled conditions in a laboratory using a gusseted thermogradient table.

Traditional thermogradient tables create a range of temperatures across the surface. Welding gussets perpendicular to the surface of a thermogradient table will control temperature in depth increasing possible research applications.

一个插角Thermogradient表来控制土壤温度为评估植物生长和监测土壤过程

Thermogradient tables were first developed in the 1950s primarily to test seed germination over a range of temperatures simultaneously without using a ...

Experimental Protocol for Detecting Cyanobacteria in Liquid and Solid Samples with an Antibody Microarray Chip

Global warming and eutrophication make some aquatic ecosystems behave as true bioreactors that trigger rapid and massive cyanobacterial growth; this has relevant health and economic consequences. Many cyanobacterial strains are toxin producers, and only a few cells are necessary to induce irreparable damage to the environment. Therefore, water-body authorities and administrations require rapid and efficient early-warning systems providing reliable data to support their preventive or curative decisions. This manuscript reports an experimental protocol for the in-field detection of toxin-producing cyanobacterial strains by using an antibody microarray chip with 17 antibodies (Abs) with taxonomic resolution (CYANOCHIP). Here, a multiplex fluorescent sandwich microarray immunoassay (FSMI) for the simultaneous monitoring of 17 cyanobacterial strains frequently found blooming in freshwater ecosystems, some of them toxin producers, is described. A microarray with multiple identical replicates (up to 24) of the CYANOCHIP was printed onto a single microscope slide to simultaneously test a similar number of samples. Liquid samples can be tested either by direct incubation with the antibodies (Abs) or after cell concentration by filtration through a 1- to 3-&#956;m filter. Solid samples, such as sediments and ground rocks, are first homogenized and dispersed by a hand-held ultrasonicator in an incubation buffer. They are then filtered (5 - 20 &#956;m) to remove the coarse material, and the filtrate is incubated with Abs. Immunoreactions are revealed by a final incubation with a mixture of the 17 fluorescence-labeled Abs and are read by a portable fluorescence detector. The whole process takes around 3 h, most of it corresponding to two 1-h periods of incubation. The output is an image, where bright spots correspond to the positive detection of cyanobacterial markers.

Experimental Protocol for Detecting Cyanobacteria in Liquid and Solid Samples with an Antibody Microarray Chip

The presence of cyanobacterial toxins in fresh water reservoirs for human consumption is a major concern for water management authorities. To evaluate the risk of water contamination, this article describes an protocol for the in-field detection of cyanobacterial strains in liquid and solid samples by using an antibody microarray chip.

用于检测实验方案<em&gt;蓝藻</em&gt;与抗体基因芯片液体和固体样品

Global warming and eutrophication make some aquatic ecosystems behave as true bioreactors that trigger rapid and massive cyanobacterial growth; this has ...

Protocols for Quantifying Transferable Pesticide Residues in Turfgrass Systems

Plant canopies in established turfgrass systems can intercept an appreciable amount of sprayed pesticides, which can be transferred through various routes onto humans. For this reason, transferable pesticide residue experiments are required for registration and re-registration by the United States Environmental Protection Agency (USEPA). Although such experiments are required, limited specificity is required pertaining to experimental approach. Experimental approaches used to assess pesticide transfer to humans including hand wiping with cotton gloves, modified California roller (moving a roller of known mass over cotton cloth) and soccer ball roll (ball wrapped with sorbent strip) over three treated turfgrass species (creeping bentgrass, hybrid bermudagrass and tall fescue maintained at 0.4, 5 and 9 cm, respectively) are presented. The modified California roller is the most extensively utilized approach to date, and is best suited for use at low mowing heights due to its reproducibility and large sampling area. The soccer ball roll is a less aggressive transfer approach; however, it mimics a very common occurrence in the most popular international sport, and has many implications for nondietary pesticide exposure from hand-to-mouth contact. Additionally, this approach may be adjusted for other athletic activities with limited modification. Hand wiping is the best approach to transfer pesticides at higher mowing heights, as roller-based approaches can lay blades over; however, it is more subjective due to more variable sampling pressure. Utility of these methods across turfgrass species is presented, and additional considerations to conduct transferable pesticide residue research in turfgrass systems are discussed.

Transferable pesticide residue experiments in turfgrass systems are integral components of human risk exposure assessments. Experimental approaches to measure transferable residues should be adjusted to the human interaction of interest and turfgrass system dynamics. Three transferable pesticide residue protocols are presented and the suitability across three turfgrass systems is discussed.

协议在草坪系统量化转换农药残留

Plant canopies in established turfgrass systems can intercept an appreciable amount of sprayed pesticides, which can be transferred through various routes ...

Nanopore DNA Sequencing for Metagenomic Soil Analysis

This article describes the steps for construction of a DNA library from soil, preparation and use of the nanopore flow cell, and analysis of the DNA sequences identified using computer software. Nanopore DNA sequencing is a flexible technique that allows for rapid microbial genome sequencing to identify bacterial and viral species, to characterize bacterial strains, and to detect genetic mutations that confer resistance to antibiotics. The advantages of nanopore sequencing (NS) for life sciences include its low complexity, reduced cost, and rapid real-time sequencing of purified genomic DNA, PCR amplicons, cDNA samples, or RNA. NS is an example of "strand sequencing" which involves sequencing DNA by guiding a single stranded DNA molecule through a nanopore that is inserted into a synthetic polymer membrane. The membrane has an electrical current applied across it, so as the individual bases pass through the nanopore the electrical current is disrupted to varying degrees by the four nucleotide bases. The identification of each nucleotide occurs by detecting the characteristic modulation of the electrical current by the different bases as they pass through the nanopore. The NS system consists of a handheld, USB powered portable device and a disposable flow cell that contains a nanopore array. The portable device plugs into a standard laptop computer that reads and records the DNA sequence using computer software.

Nanopore technology for sequencing biomolecules has wide applications in the life sciences, including identification of pathogens, food safety monitoring, genomic analysis, metagenomic environmental monitoring, and characterization of bacterial antibiotic resistance. In this article, the procedure for metagenomic soil DNA sequencing for species identification using the nanopore sequencing technology is demonstrated.

基因土壤分析的纳米 DNA 测序

This article describes the steps for construction of a DNA library from soil, preparation and use of the nanopore flow cell, and analysis of the DNA ...

Measuring and Mapping Patterns of Soil Erosion and Deposition Related to Soil Carbonate Concentrations Under Agricultural Management

Spatial patterns of soil erosion and deposition can be inferred from differences in ground elevation mapped at appropriate time increments. Such changes in elevation are related to changes in near-surface soil carbonate (CaCO3) profiles. The objective is to describe a simple conceptual model and detailed protocol for repeatable field and laboratory measurements of these quantities. Here, accurate elevation is measured using a ground-based differential global positioning system (GPS); other data acquisition methods could be applied to the same basic method. Soil samples are collected from prescribed depth intervals and analyzed in the lab using an efficient and precise modified pressure-calcimeter method for quantitative analysis of inorganic carbon concentration. Standard statistical methods are applied to point data, and representative results show significant correlations between changes in soil surface layer CaCO3 and changes in elevation consistent with the conceptual model; CaCO3 generally decreased in depositional areas and increased in erosional areas. Maps are derived from point measurements of elevation and soil CaCO3 to aid analyses. A map of erosional and depositional patterns at the study site, a rain-fed winter wheat field cropped in alternating wheat-fallow strips, shows the interacting effects of water and wind erosion affected by management and topography. Alternative sampling methods and depth intervals are discussed and recommended for future work relating soil erosion and deposition to soil CaCO3.

Spatial patterns of soil erosion and deposition can be inferred from differences in ground elevation mapped at appropriate time increments. Such changes in elevation are related to changes in near-surface soil carbonates. Repeatable methods for field and laboratory measurements of these quantities and data analysis methods are described here.

农业经营条件下土壤侵蚀和沉积与土壤碳酸盐浓度关系的测量与制图

Spatial patterns of soil erosion and deposition can be inferred from differences in ground elevation mapped at appropriate time increments. Such changes ...

Experimental Protocol for Detecting Mitochondrial Function in Hepatocytes Exposed to Organochlorine Pesticides

This paper presents detailed methods on detecting hepatic mitochondrial function for a better understanding the cause of metabolic disorders caused by environmental organochlorine pesticides (OCPs) in hepatocytes. HepG2 cells were exposed to &#946;-hexachlorocyclohexane (&#946;-HCH) for 24 h at an equivalent dose of internal exposure in general population. Ultrastructure in hepatocytes was examined by transmission electron microscopy (TEM) to show the damage of mitochondria. Mitochondrial function was further evaluated by mitochondrial fluorescence intensity, adenosine 5'-triphosphate (ATP) levels, oxygen consumption rate (OCR) and mitochondrial membrane potential (MMP) in HepG2 cells incubated with &#946;-HCH. The mitochondria fluorescence intensity after stained by mitochondrial green fluorescent probe was observed with a fluorescence microscopy. The luciferin-luciferase reaction was used to determine ATP levels. The MMP was detected by the cationic dye JC-1 and analyzed under flow cytometry. OCR was measured with an extracellular flux analyzer. In summary, these protocols were used in detecting mitochondrial function in hepatocytes with to investigate mitochondria damages.

Understanding the influence of environmental organochlorine pesticides (OCPs) on mitochondrial function in hepatocytes is important in exploring the mechanism of OCPs causing metabolic disorders. This paper presents detailed methods on detecting hepatic mitochondrial function.

检测暴露于有机氯农药的肝细胞线粒体功能的实验方案

This paper presents detailed methods on detecting hepatic mitochondrial function for a better understanding the cause of metabolic disorders caused by ...