NURSERY FERTILIZATION AND UNDERSTORY COMPETITION AFFECT SEEDLING GROWTH IN OIL SANDS RECLAIMED SOILS IN ALBERTA

• Author / Creator

  Pokharel, Prem

• Revegetation in the oil sands mining areas in northern Alberta has often been difficult because of high mortality and slow growth of planted seedlings on reclaimed soils. Growth of the planted seedlings is limited by low nutrient and water availability in the soil on reclaimed sites. Management practices such as nursery fertilization to produce quality planting stock, field weed control and fertilization could help improve the early establishment of planted seedlings and reclamation success. The main goal of this study was to examine the potential application of the nutrient loading technique (nursery fertilization) to enhance revegetation success in oil sands reclaimed soils. We hypothesized that i) nursery nutrient loading can build up nutrient reserves in the seedlings that would improve seedlings early growth after outplanting by increasing nutrient retranslocation within the seedlings and ii) weed control can improve seedlings growth by increasing nutrient availability in the soil in highly competitive reclamation sites. I studied the growth and biomass allocation, nitrogen (N) retranslocation within the seedling components and N uptake from the soil in nutrient-loaded (by exponential fertilization) seedlings planted on oil sands reclaimed sites in field experiments for two years. Nitrogen retranslocation and N uptake from the soil were traced using 15N labeling and soil N availability was determined using foliar δ13C.The application of exponential fertilization to enhance revegetation on reclaimed mine sites is relatively new. The use of 15N isotope to discriminate various N pools in new tissues and 13C isotope to determine soil N availability and N uptake by nutrient loaded seedlings is the novel aspect of this study. Seedlings were produced by loading of nutrients (essential macro and micro nutrients) with balanced fertilizers in nursery. In the first experiment, growth and N retranslocation in trembling aspen (Populus tremuloides Michx.) were examined on two reclaimed sites, one with peat mineral soil mix (PMM) and the other with LFH mineral soil mix (LFH) as cover materials. In the second and third experiments, growth and N retranslocation in jack pine (Pinus banksiana Lamb.) and white spruce (Picea glauca [Moench] Voss) seedlings were examined on the PMM site. The results showed that at the end of nursery production N reserve was increased in aspen and jack pine but not in white spruce seedlings by exponential fertilization. The growth, N retranslocation into new tissues from old tissues and N uptake from the soil in aspen seedlings in the field were increased by exponential fertilization and weed control. Weed competition for aspen growth was more prominent on the LFH site than on the PMM site. In the second experiment, exponential fertilization increased the growth, N retranslocation and N uptake from the soil in jack pine seedlings while weed control decreased N retranslocation and increased N uptake with no significant change in seedling growth. In both aspen and jack pine, exponentially fertilized seedlings allocated greater biomass into metabolically active tissues such as current –year leaf and stem than conventionally fertilized ones. In white spruce, exponential fertilization increased relative height growth but not absolute height, RCD and seedling component biomass. Weed control increased soil N availability, N uptake from the soil, N retranslocation and growth of white spruce seedlings in second year after outplanting. We concluded that the effects of vegetation management practices on the growth and N retranslocation in planted seedlings varies with the species and cover soil type on reclaimed sites. Nursery nutrient loading has the potential to help enhance revegetation success by improving growth of aspen on both sites and jack pine seedlings on the PMM site, while weed control improves the growth of aspen seedlings planted on the LFH site and white spruce planted on the PMM site. Exponential fertilization was not able to build up nutrient reserves in white spruce seedlings at nursery production suggesting that further research on loading of nutrients into this species is needed.

• Subjects / Keywords

  • PMM and LFH
  • Biomass allocation
  • Nitrogen uptake
  • Nitrogen retranslocation
  • Nutrient loading
  • 15N isotope
  • Exponential fertilization
  • Foliar δ13C

• Graduation date

  Spring 2017

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R3X63BH85

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.