Reclaimed Oil Sands Exploration sites Alberta - Carbon Flux and Environmental Variables

Two oil sands exploration (OSE) sites were studied: a site reclaimed in 2009 (old) and a site reclaimed in 2012 (new). A natural site was also studied (NAT). Plots were named as follows, based on management technique at the OSE sites: control with no reclamation technique (C), wet control (C-w), coarse woody debris additions (CWD), mechanical mounding and planting trees, mound (M-m), mechanical mounding and planting trees, pool (M-p), planting trees only (PAI). Carbon dioxide and methane flux measurements made between May and September of 2017 and 2018 using the closed chamber method. Measurements for water table depth (WT - negative means depth below the surface) and soil temperature at 2 cm depth (T2) to 20 cm depth (T20) were made adjacent to each flux plot at the time of a carbon dioxide or methane measurement. GEP (gross ecosystem productivity) is the difference between NEE (net ecosystem exchange) and ER (ecosystem respiration), and negative GEP and NEE values represent a sink of carbon dioxide from the atmosphere to the soil. PAR is photosynthetically active radiation. Plot vegetation cover was measured in August. Water table, temperature at 5 cm depth, and PAR were logged during the study period using sensors. Tree quadrats were located in the vicinity of the carbon flux plots.本研究选取3处油砂勘探（oil sands exploration, OSE）场地开展试验：分别为2009年完成生态修复的旧场地、2012年完成生态修复的新场地，以及一处天然对照场地（NAT）。依据油砂勘探场地的管理措施，各试验地块命名规则如下：无任何修复技术的对照组（C）、湿生对照组（C-w）、粗木质残体添加组（CWD）、机械堆土并植树的堆丘组（M-m）、机械堆土并植树的池状组（M-p），以及仅植树组（PAI）。2017年与2018年的5—9月期间，研究采用静态箱法对各地块的二氧化碳与甲烷通量进行测定。在每次二氧化碳或甲烷通量测定时，同步于各通量地块的邻近位置开展地下水位深度（WT，负值代表地表以下的埋藏深度）以及2cm深度（T2）至20cm深度（T20）的土壤温度测定。总生态系统生产力（gross ecosystem productivity, GEP）为净生态系统交换（net ecosystem exchange, NEE）与生态系统呼吸（ecosystem respiration, ER）的差值；当GEP与NEE为负值时，表明存在碳汇过程，即大气中的二氧化碳向土壤中固存。光合有效辐射（photosynthetically active radiation, PAR）。各地块的植被盖度于当年8月完成测定。研究期间，通过传感器连续记录地下水位、5cm深度土壤温度以及光合有效辐射（PAR）数据。树木样方设置于各碳通量地块的邻近区域。