Impacts of non-native plants in oil sands mine reclamation

Transcription

1 Impacts of non-native plants in oil sands mine reclamation Brad Pinno November 14, 2017 Co-authors: Ruth Errington, Ira Sherr, Leah debortoli, Pierre-Yves Tremblay, Jenn Buss, Kyle Stratechuk, Sanatan Das Gupta, Edith Li

2 Weeds plants in the wrong place What are weeds? What are the impacts of weeds? How do reclamation practices impact weeds? Long-term solutions

3 Native vs non-native species Most native plants are quite infrequent Non-native plant community dominated by a few ubiquitous species Most weeds are ruderals adapted to disturbed environments Related to modes of dispersal and establishment Frequency of species occurrence FFMM - native Cumulative number of species FFMM - non-native PMM - native PMM - non-native Grow and reproduce quickly Pinno et al Islands soil patches and plant community dynamics on a new oil sands reclamation design. JASMR. 5:28-44.

4 Temporal trends CEMA Long term plot network Weed cover drop off dramatically after the first few years Still 10% weed cover after 20 years On what soil types? Management practices? Pinno and Hawkes Temporal trends of ecosystem development on different site types in reclaimed boreal forests. Forests. 6: Year 1 Year 15

5 Not all species are the same! Long-term grassland restoration experiment with disturbance and fertility treatments Clearly different responses among species Time, disturbance, soil, fertility and management practices are all important factors Need to understand the species you are dealing with both desirable and undesirable species Canada thistle increased with time and disturbance Crested wheat grass decreased with time and disturbance Native woody species only survived with no disturbance and low fertility Wilson and Pinno Environmentally-contingent behaviour of grassland plants as drivers or passengers. Oikos. 122:

6 Where are plants coming from? Seedbank from soil placed during reclamation operations? Soil cores from natural forests and from directly placed reclamation material. Seeding in from offsite? Seed traps placed across soil type boundary. Vegetative expansion? Germinating in greenhouse to determine species and abundance. Trying to determine the mechanisms of plant establishment. Next step is quantifying competition.

7 Impact on trees Aspen seedling establishment greater with weeding Likely competing for the same microsites 8,000 more seedlings per ha on PMM with weeding L debortoli. MSc thesis. Aspen is more impacted by competition than spruce Is the impact of weeds on trees greater than native species? Aspen Spruce PY Tremblay. MSc thesis.

8 Impact on native plants Non-native cover does appear to limit the maximum native cover Over 15% non-native cover seems to be a threshold Native species richness does not seem to be impacted by weeds Most native species are relatively rare

9 Reclamation soil type RA1 PMM, FFMM with and without fertilization Lots of weeds after 3 years on many reclamation sites Higher weed cover and richness on FFMM vs PMM soil Fertilization increases weed cover Errington and Pinno Early successional plant community dynamics on a reclaimed oil sands mine in comparison with natural boreal forest communities. Ecoscience. 22:

10 Greenhouse experiment 3 species x mixtures Galium boreale Vicia americana Matricari perforata 3 soil types PMM, FFMM, layered 2 fertilizer types Plant growth response varied by soil type and fertility Plant biomass per pot (g) G. boreale M. perforata V. americana Total N (µg/10cm 2 /35 days) Buss, Stratechuk, and Pinno. Growth and competition among understory plants varies with reclamation soil and fertilization. Submitted to Ecological Processes.

11 Competition varies Higher fertility soil, Matricaria outperforms native species On poorer soil, Vicia outperforms Galium mortality was minimal on high fertility soil but was high on low fertility soil with competition Mortality rate of G. boreale Average aboveground biomass per pot (g) FFMM Layered PMM FFMM Layered PMM FFMM Layered PMM G. boreale-m. perforata V. americana-g. boreale V. americana-m. perforata Galium mortality FFMM Layered PMM V. americana M. perforata G. boreale

12 Woody debris Woody debris applications impacts plant communities Relative cover of native forbs increases with woody debris Non-native species cover was reduced at even low debris levels (0-30%) Shift in the balance of power towards native plants Relative Cover Non-native spp. cover Native species cover (%) None Low Moderate High None Low Moderate High None Low Moderate High None Low Moderate FFMM PMM Fire Mature High natforb gram moss FFMM woody PMM Fire intro FFMM PMM Fire

13 Weeding experiment Controlled weeds by hand on 3 different reclamation soil types More plant diversity and cover (including weeds) on FFMM compared to PMM Impacts of weeding varied by soil type L debortoli MSc thesis

14 Weeding impacts No benefit of weeding on PMM reclamation soils which had abundant bare ground and low plant diversity Weeding FFMM did change the plant community Increase in Calamagrostis Potential long term problem? PMM soil FFMM soil Unintended consequences of weeding! Calamagrostis canadensis

15 Canopy cover is critical In the long-term, establishing forest canopy cover is critical Increased canopy cover related to decreases in weeds and increases in native plants Less of these sites More of these sites

16 Thanks!