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

油砂地区约有6500公顷的复垦景观，其中大部分由覆盖层中盐分含量较高的材料组成，顶部覆盖着厚达1.5米的泥炭/矿物土壤。覆盖物厚度具有生态意义，因为较厚的覆盖物将最大限度地减少覆盖层向上盐分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，更厚的封面成本更高，这对公司有经济影响。这些盖子应该有多厚？要回答这个问题，我们需要知道北方树种，如杨树和云杉的根系是如何受到盐度和覆盖厚度的影响的。在这些盐碱条件下，根系是否表现出足够的可塑性，以支持健康的森林？这些复垦植被上的根系分布如何模拟天然盐碱地或非盐碱地的根系分布？最近的研究表明，从这些开垦景观中收集的根样本在盐碱地超载中被发现。然而，由于形态识别技术的不足，我们不知道这些根是属于那里种植的理想北方树种，还是来自林下植被。因此，目标是1)利用DNA测序技术确定不同树种(杨树、云杉、精选林下)在天然林、天然盐碱地和不同厚度的复垦盐碱景观中的生根分布；2)使用微型加速器(地下相机)和示踪技术量化复垦景观中与自然林相比的根系动态和功能；以及3)利用三维根构型模型确定杨树和云杉根系对盐分条件的可塑性。为了奥贝。1根将从天然林分、天然盐碱地和不同厚度的复垦盐碱景观中采集，并通过DNA测序技术进行鉴定，以确定根系在土壤剖面中的分布位置。OBJ中的根系动态。2将在填海和自然场地使用迷你加速器进行测量，在那里将透明的塑料管插入地面，并用微型摄像机每月收集根部图像。根功能(N吸收)将使用放置在不同深度的稳定示踪剂进行测量，并在植被的地上部分进行测量。目的：研究不同植物根系的可塑性。3、利用从开挖的根系中获得的输入参数，建立三维根构型模型，模拟不同覆盖厚度和盐分分布对根系可塑性和根系发育的影响。这项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开垦的景观，并通过确保根系与天然森林相比正常发育，将覆盖失败的风险降至最低。

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.