Root identification, dynamics and plasticity of boreal species on reclaimed saline-sodic overburdens and naturally saline sites

再生盐碱覆盖层和天然盐碱地北方物种的根系识别、动态和可塑性

• 批准号: RGPIN-2014-05372
• 负责人: VanRees, Ken
• 金额: $ 1.75万
• 依托单位: University of Saskatchewan
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=567126
• 关键词: Root; identification; dynamics; plasticity; boreal

There are about 6500 ha of reclaimed landscapes in the oil sands region, the majority of which consists of materials with high levels of salts in the overburden that is capped on top with a peat/mineral soil cover up to 1.5 m thick. The thickness of these covers has ecological implications in that thicker covers will minimize negative effects of salt migration from the overburden into the cover on root systems but also reduce water yield for downstream wetlands. In addition, thicker covers are more expensive to design and thus have economic ramifications for companies. How thick should these covers actually be? To answer that we need to know how root systems for boreal species such as aspen and spruce are impacted by cover thickness - do roots of these planted trees actually occupy the entire soil profile, or are they restricted to just the soil surface due to the upward migrating salt profiles? Do roots of boreal species demonstrate enough plasticity to develop under these salinity conditions in order to support a healthy forest and how do root distributions on these reclaimed covers mimic root distributions found on naturally saline or non-saline sites? Recent research has shown that root samples collected from these reclaimed landscapes are found in the high salt overburdens. However, we do not know if these roots belong to the desired boreal tree species planted there or from understory vegetation or weeds because of inadequacies of morphological root identification techniques. Therefore the objectives of this proposal are to 1) determine the rooting distribution by species (aspen, spruce, selected understory) using DNA sequencing techniques and their morphological traits in natural stands, naturally saline sites, and reclaimed saline-sodic landscapes of varying thickness; 2) quantify root dynamics and activity in reclaimed landscapes compared to natural stands using minirhizotron (clear tubes in the ground that use cameras to capture root images) and tracer techniques coupled with DNA sequencing; and 3) determine the plasticity of aspen and spruce roots to saline-sodic conditions using 3D root architecture models. For Obj. 1 roots will be collected from natural stands, naturally saline sites, and reclaimed saline-sodic landscapes of varying thickness and identified with DNA sequencing techniques to conclusively know where in the soil profiles the root systems are distributed. Root characteristics will also be measured to determine the plasticity of the roots between the overburden and cover layers compared with natural and naturally saline sites. Root dynamics in Obj. 2 will be measured in reclaimed and natural sites using minirhizotrons where clear plastic tubes are inserted into the ground and root images collected on a monthly basis with a miniature video camera. The activity of the roots will be measured using stable tracers placed at various depths and measured in the aboveground portion of the vegetation. To investigate root plasticity of these root systems in Obj. 3 a 3D root architecture model will be used with input parameters obtained from excavated root systems to model the effect of varying cover thicknesses and migrating salt profiles on root plasticity and root development. This project is novel in that it uses DNA sequencing techniques to actually identify individual roots to understand how cover thickness is affecting root development and thus tree growth as well as providing a tool for predicting the effects of salts and cover thickness on root development. This program will provide results that are significant to oil sand companies and regulators in certifying reclaimed landscapes and minimize risks of cover failure by ensuring that root systems are developing properly compared to natural forests.

油砂地区有约 6500 公顷的开垦景观，其中大部分由覆盖层中含盐量高的物质组成，覆盖层顶部覆盖着厚度达 1.5 m 的泥炭/矿质土壤。这些覆盖层的厚度具有生态意义，因为较厚的覆盖层可以最大限度地减少盐分从覆盖层迁移到覆盖层对根系的负面影响，但也会减少下游湿地的产水量。此外，较厚的盖子设计成本更高，因此会给公司带来经济影响。这些盖子实际上应该有多厚？为了回答这个问题，我们需要知道白杨和云杉等北方树种的根系如何受到覆盖厚度的影响——这些种植树木的根实际上占据了整个土壤剖面，还是由于向上迁移的盐剖面而仅限于土壤表面？北方物种的根系是否表现出足够的可塑性，可以在这些盐度条件下发育，以支持健康的森林？这些开垦覆盖物上的根系分布如何模仿天然盐碱地或非盐碱地的根系分布？最近的研究表明，从这些开垦的景观中收集的根部样本是在高盐覆盖层中发现的。然而，由于形态根识别技术的不足，我们不知道这些根是否属于种植在那里的所需北方树种，还是来自林下植被或杂草。因此，本提案的目标是 1) 使用 DNA 测序技术及其在自然林分、天然盐碱地和不同厚度的再生盐碱景观中的形态特征，确定按物种（白杨、云杉、选定的林下植物）的生根分布； 2) 使用微型根管管（地下的透明管，使用摄像机捕获根部图像）和示踪剂技术结合 DNA 测序，与自然林分相比，量化开垦景观中的根系动态和活动； 3) 使用 3D 根结构模型确定白杨和云杉根在盐碱条件下的可塑性。对于对象。 1 根系将从不同厚度的自然林分、天然盐碱地和再生盐碱地景观中收集，并通过 DNA 测序技术进行识别，以最终了解根系在土壤剖面中的分布位置。还将测量根部特征，以确定与天然和天然盐碱地相比，覆盖层和覆盖层之间的根部的可塑性。 Obj 中的根动态。 2 将使用微型根管在开垦和自然地点进行测量，其中将透明塑料管插入地面，并使用微型摄像机每月收集根部图像。将使用放置在不同深度并在植被的地上部分测量的稳定示踪剂来测量根的活动。研究 Obj 中这些根系的根可塑性。 3 将使用 3D 根系结构模型以及从挖掘的根系获得的输入参数来模拟不同覆盖厚度和盐迁移剖面对根系可塑性和根系发育的影响。该项目的新颖之处在于，它使用 DNA 测序技术来实际识别单个根，以了解覆盖厚度如何影响根系发育，从而影响树木生长，并提供预测盐和覆盖厚度对根系发育影响的工具。该计划将提供对油砂公司和监管机构在认证开垦景观方面具有重要意义的结果，并通过确保根系与天然林相比正常发育来最大限度地降低覆盖失败的风险。