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

油砂地区约有6500公顷的再生景观，其中大部分由覆盖层中含高盐量的材料组成，顶部覆盖着厚达1.5米的泥炭/矿物土壤。覆盖层厚度具有生态影响，因为较厚的覆盖层将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水量。此外，较厚的覆盖物成本更高，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，我们需要知道北方树种，如白杨和云杉的根系是如何受到盐度和覆盖厚度的影响的。根系是否表现出足够的可塑性，在这些盐碱条件下发展，以支持一个健康的森林，以及如何根分布在这些回收覆盖模仿自然盐碱或非盐碱地发现的根分布？最近的研究表明，从这些开垦景观中收集的根系样本被发现在盐超载。然而，我们不知道这些根是否属于所需的北方树种种植在那里或林下植被，因为形态根识别技术的不足。因此，目标是：1）确定物种的生根分布（白杨，云杉，选定的林下植物）使用DNA测序技术在自然林分，天然盐碱地，和不同厚度的开垦盐碱地景观; 2）量化根动态和功能，在开垦景观相比，自然林分使用微型电子显微镜（地下照相机）和示踪技术;和3）使用3D根构型模型确定白杨和云杉根对盐度条件的可塑性。对于目标1，将从不同厚度的天然林分、天然盐碱地和开垦的盐碱地景观中收集根系，并利用DNA测序技术进行鉴定，以最终了解根系在土壤剖面中的分布位置。目标2中的根系动态将在复垦和自然场地中使用微型电子显微镜进行测量，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系图像。根系功能（氮吸收）将使用稳定的示踪剂放置在不同的深度和测量植被的地上部分。为了研究目标3中这些根系的根可塑性，将使用三维根构型模型，输入参数从挖掘的根系中获得，以模拟不同覆盖厚度和迁移盐剖面对根可塑性和根发育的影响。该提案将为油砂公司和监管机构提供结果，这些结果将有助于认证回收景观，并通过确保根系与天然森林相比正常发育，最大限度地减少覆盖失败的风险。

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.