Root 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动态和可塑性。

• 批准号: RGPIN-2015-04420
• 负责人: VanRees, Ken
• 金额: $ 2.4万
• 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: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=667548
• 关键词: Root; dynamics; plasticity; boreal; species

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 capped on top with a peat/mineral soil cover up to 1.5m thick. Cover thickness has ecological implications in that thicker covers will minimize negative effects of upward salt migration from the overburden on root systems but also reduce water yield for downstream wetlands. In addition, thicker covers cost more which has economic ramifications for companies. How thick should these covers be? To answer that we need to know how root systems for boreal species such as aspen and spruce are impacted by salinity and cover thickness. Do roots systems demonstrate enough plasticity to develop under these saline conditions 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 saline overburdens. However, we do not know if these roots belong to the desired boreal tree species planted there or from understory vegetation because of inadequacies of morphological root identification techniques. Therefore the objectives are to 1) determine the rooting distribution by species (aspen, spruce, selected understory) using DNA sequencing techniques in natural stands, naturally saline sites, and reclaimed saline-sodic landscapes of varying thickness; 2) quantify root dynamics and function in reclaimed landscapes compared to natural stands using minirhizotron (underground camera) and tracer techniques; and 3) determine the plasticity of aspen and spruce roots to salinity 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 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. Root function (N uptake) 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 proposal will provide oil sand companies and regulators with results that will help 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，顶部覆盖着厚达 1.5m 的泥炭/矿质土壤。覆盖厚度具有生态意义，因为较厚的覆盖物可以最大限度地减少盐分从覆盖层向上迁移对根系的负面影响，但也会减少下游湿地的产水量。此外，较厚的覆盖层成本更高，这对公司有经济影响。这些盖子应该有多厚？为了回答这个问题，我们需要知道白杨和云杉等北方物种的根系如何受到盐度和覆盖厚度的影响。根系是否表现出足够的可塑性，可以在这些盐分条件下发育以支持健康的森林？这些回收覆盖物上的根系分布如何模仿天然盐分或非盐分地点的根系分布？最近的研究表明，从这些开垦的景观中收集的根系样本是在盐渍覆盖层中发现的。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。因此，目标是 1) 使用 DNA 测序技术在自然林分、天然盐碱地和不同厚度的再生盐碱景观中按物种（白杨、云杉、选定的林下植物）确定根分布； 2) 使用 minirhizotron（地下摄像机）和示踪剂技术，与自然林分相比，量化复垦景观中的根系动态和功能； 3) 使用 3D 根结构模型确定白杨和云杉根对盐度条件的可塑性。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。 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功能（氮吸收）。研究 Obj 中这些根系的根可塑性。如图 3 所示，3D 根系结构模型将与从挖掘的根系获得的输入参数一起使用，以模拟不同覆盖厚度和迁移盐分布对根系可塑性和根系发育的影响。该提案将为油砂公司和监管机构提供结果，有助于认证开垦景观，并通过确保根系与天然林相比正常发育，最大限度地降低覆盖失败的风险。