Data from: Fine root dynamics in lodgepole pine and white spruce stands along productivity gradients in reclaimed oil sands sites

Open-pit mining activities in the oil sands region of Alberta, Canada, create disturbed lands that, by law, must be reclaimed to a land capability equivalent to that existed before the disturbance. Re-establishment of forest cover will be affected by the production and turnover rate of fine roots. However, the relationship between fine root dynamics and tree growth has not been studied in reclaimed oil sands sites. Fine root properties (root length density, mean surface area, total root biomass, and rates of root production, turnover, and decomposition) were assessed from May to October 2011 and 2012 using sequential coring and ingrowth core methods in lodgepole pine (Pinus contorta Dougl.) and white spruce (Picea glauca (Moench.) Voss) stands. The pine and spruce stands were planted on peat mineral soil mix placed over tailings sand and overburden substrates, respectively, in reclaimed oil sands sites in Alberta. We selected stands that form a productivity gradient (low, medium, and high productivities) of each tree species based on differences in tree height and diameter at breast height (DBH) increments. In lodgepole pine stands, fine root length density and fine root production, and turnover rates were in the order of high > medium > low productivity sites and were positively correlated with tree height and DBH and negatively correlated with soil salinity (P < 0.05). In white spruce stands, fine root surface area was the only parameter that increased along the productivity gradient and was negatively correlated with soil compaction. In conclusion, fine root dynamics along the stand productivity gradients were closely linked to stand productivity and were affected by limiting soil properties related to the specific substrate used for reconstructing the reclaimed soil. Understanding the impact of soil properties on fine root dynamics and overall stand productivity will help improve land reclamation outcomes.

加拿大阿尔伯塔省油砂矿区的露天采矿活动会产生受扰动土地，根据当地法律规定，此类土地必须被修复至与扰动前等效的土地生产能力。森林覆盖的重建将受细根产生与周转速率的影响，但目前尚未有研究针对修复后油砂场地中的细根动态与树木生长之间的关系展开探讨。2011年5月至10月及2012年，研究团队采用连续钻芯法（sequential coring）与内生长芯法（ingrowth core method），在扭叶松（Pinus contorta Dougl.）和白云杉（Picea glauca (Moench.) Voss）林分中测定了多项细根性状：细根长度密度、平均根表面积、总根生物量，以及细根产生、周转与分解速率。上述林分分别被种植于覆盖尾矿砂的泥炭-矿质土壤混合物，以及覆盖剥离物基质的修复后油砂场地中。研究团队基于树木树高与胸径（diameter at breast height, DBH）的增量差异，选取了各树种形成生产力梯度（低、中、高生产力）的林分。在扭叶松林分中，细根长度密度、细根产生速率与周转速率均呈现高生产力样地＞中生产力样地＞低生产力样地的顺序，且与树高、胸径呈正相关，与土壤盐度呈负相关（P < 0.05）。在白云杉林分中，细根表面积是唯一随生产力梯度升高而增加的参数，且与土壤紧实度呈负相关。综上，沿林分生产力梯度分布的细根动态与林分生产力紧密相关，并受修复土壤构建过程中所用特定基质相关的限制性土壤性质影响。明晰土壤性质对细根动态及整体林分生产力的影响，将有助于提升土地修复成效。